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Hashiguchi, Tatsuki, Kyohei Azuma, Rin Nishinaka, Ayumu Matsumoto, and Shinji Yae. "General Corrosion and Electrode Potential in Metal-Nanoparticle-Assisted Etching of p-Type and n-Type Silicon Using Gold and Silver." ECS Meeting Abstracts MA2024-02, no. 67 (2024): 4567. https://doi.org/10.1149/ma2024-02674567mtgabs.
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Introduction When silicon (Si) modified with noble metal catalysts is immersed in a hydrofluoric acid (HF) aqueous solution containing an oxidizing agent, such as hydrogen peroxide (H2O2), a porous layer is formed on the Si surface [1]. This phenomenon is called metal-assisted etching, and it has attracted attention as a new method for producing porous Si. The etching reaction is explained by a local cell mechanism consisting of a cathodic reaction in which the oxidizing agent is reduced on the metal catalysts and an anodic reaction in which Si is oxidized. It is known that etching behavior varies greatly depending on the type of metal catalysts and other treatment conditions, but the mechanism is not clear. We have previously reported that the entire Si surface is dissolved during metal-assisted etching, resulting in general corrosion [2]. In this study, metal-assisted etching of p-type and n-type Si was performed using gold (Au) and silver (Ag) nanoparticles, and the general corrosion depth and the potential of Si during etching were investigated. Experimental Single crystal p-type and n-type Si wafers (CZ, (100), 0.5~10 Ωcm) were used as the Si substrates. The pretreated Si substrate was immersed in a tetrachloroauric(III) acid aqueous solution or a silver(I) nitrate aqueous solution containing 0.15 M HF, and Au or Ag nanoparticles were deposited on Si with the metal coverage of approximately 40%. The metal-deposited Si was immersed in a 6.6 M HF aqueous solution containing 0.1 M H2O2 for 120 s in the dark. The general corrosion depth was estimated from the mass loss of the Si substrate and the depth of pores observed with scanning electron microscope (SEM) [2]. The potential of Si during etching was measured using an electrochemical cell with a platinum ring as the counter electrode and a silver/silver chloride (Ag/AgCl) electrode as the reference electrode. Results and discussion Figure 1 shows a schematic illustration of cross sections of Si after etching. Under all conditions, the Si surface beneath the metal particles was dissolved and vertical pores were formed. The pore depth formed by the Ag-assisted-etching was larger than that formed by the Au-assisted etching. On the other hand, the general corrosion depth in the Ag-assisted etching was smaller than that in the Au-assisted etching. In the case of Ag-assisted etching of n-Si, the general corrosion did not occur. As for the potential during etching, the potential was shifted to positive direction by the deposition of metal particles, except for the Ag-deposited n-Si. The positive shift of potential indicates that the Si substrate is anodically polarized during etching and the Si surface away from the metal catalysts can be dissolved. This corresponds to the results that the general corrosion occurred in the Au-assisted etching of p/n-Si and Ag-assisted etching of p-Si. On the other hand, the potential of n-Si was not shifted by the deposition of Ag nanoparticles, and the general corrosion did not occur in the Ag-assisted etching of n-Si. These results suggest that the potential during etching contributes to general corrosion. [1] Z. Huang, N. Geyer, P. Werner, U. Gösele ; Adv. Mater., 23, 285 (2011). [2] A. Matsumoto, H. Son, M. Eguchi, K. Iwamoto, Y. Shimada, K. Furukawa, S. Yae ; RSC Adv., 10, 289 (2020). Figure 1
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Huang, Yan Tang, Xiao Hua Wang, and Ri Yan Bao. "Etching Method of the Fabrication Optical Tapered Fiber and its Formula." Applied Mechanics and Materials 145 (December 2011): 520–24. http://dx.doi.org/10.4028/www.scientific.net/amm.145.520.
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Optical tapered fiber is one of the most high efficiency evanescent wave coupler for coupling light into and out the optical microcavity. We fabricated the tapered fiber with etching method in a designed groove with HF solution. This method was low cost, readily, and controllable. An etching groove had an oval in the middle and small V-shape towards both sides. HF solution was injected into the oval groove, while the deioned water was injected into the two V-grooves. Because of the solution diffusion, the etching rate was fast in the mid and decreased gradually towards both sides,the tapered fiber was fabricated. The optical power meter was monitoring the fiber transmission during the etching process. The transmission of the tapered fiber was 98%. We proposed a mathematics model to depict the etching process, containing the relationship between the diameter of tapered fiber and the concentration of the HF solution, the etching time, humidity, temperature. We supervised the optical intensity to deduce the tapered fiber diameter. Surface morphology with AFM was detected, the roughness of the tapered fiber surface is less than 1nm. As an evanescent coupler, we used the tapered fiber to transmit 980nm pump laser to couple to Er3+doped microsphere to stimulate 1557nm laser.
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KIM, Bumsik, Wonje Lee, and Sangwoo Lim. "Selective Etching of SiO2 over Si3N4 through Varying the Concentration of Fluorine Species." ECS Meeting Abstracts MA2024-02, no. 31 (2024): 2268. https://doi.org/10.1149/ma2024-02312268mtgabs.
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Silicon dioxide (SiO2) and silicon nitride (Si3N4) are widely used as an insulating layer to separate interconnection, due to the characteristic of their wide band gap. As the feature size of semiconductors has been continuously decreasing and their structures have become more complex recent years, SiO2 as an insulating layer is reaching its limit. One of the ways to overcome this limitation, next generation 3D structure semiconductors are developed. In order to manufacture these kinds of devices, a removal of SiO2 is required, however, as both SiO2 and Si3N4 layers are revealed, the highly selective SiO2 etching process over Si3N4 is needed. If the Si3N4 layers were etched during the SiO2 layer etching process, the Si3N4 layer could not be function as an insulating layer and an etch stop layer. As an etchant for the SiO2 layer, hydrofluoric acid (HF) and ammonium fluoride (NH4F) combining solution is mainly used. However, it is known that HF solution also causes the material loss of the Si3N4 layers. Therefore, the study of etching behaviors of SiO2 and Si3N4 in HF solution is needed. In HF solutions, main etching species of SiO2 and Si3N4 exists as fluorine species. The concentration of these fluorine species depends on various conditions, such as pH of the solution or the composition of HF and NH4F. Therefore, the dependence of SiO2 and Si3N4 etching rates on the conditions of HF solutions were investigated. To investigate the etching rates of SiO2 and Si3N4, the blanket SiO2 and Si3N4 wafer in which deposited on Si wafer by the low-pressured chemical vapor deposition method were used, respectively. A patterned SiO2/Si3N4 multi-stack structures were fabricated by plasma-enhanced chemical vapor deposition, to verify whether SiO2 was selectively etched over Si3N4 in HF solution. The HF solutions were prepared by adding various concentrations of HF to deionized water and NH4F was added in some cases. The pH of the HF solution was controlled by adding hydrochloric acid or ammonium hydroxide. The temperature maintained at 25 °C during the etching processes using a water bath. The blanket SiO2 and Si3N4 wafers were immersed in these solutions for 3 and 60 mins, respectively. The etching depth of the SiO2 and Si3N4 films was measured by spectroscopic ellipsometry. The morphology of patterned SiO2/Si3N4 multi-stack structures after etching process was observed using field-emission scanning electron microscopy (FE-SEM). The pH and the concentrations of each fluorine species of the prepared HF solutions were calculated based on the equilibrium constants, molar balance, and charge balance. To obtain the HF solution with the high SiO2 etching selectivity over Si3N4, blanket SiO2 and Si3N4 wafers were etched under various pH and initial concentrations of HF solution. As the pH of the HF solution was increased, at the same initial HF concentration, the SiO2/Si3N4 etching selectivity was increased. Meanwhile, the etching selectivity of SiO2 over Si3N4 was increased with the initial concentrations of HF increased, at a fixed pH of the solution. To investigate the reason for the dependencies of the SiO2 and Si3N4 etching rates on pH and initial concentrations of HF, the concentrations of each fluorine species were calculated. As a result, the etching mechanisms and the etching behaviors of SiO2 and Si3N4 in the HF solutions were suggested. Based on the etching kinetics of SiO2 and Si3N4, a patterned SiO2/Si3N4 multi-stack structure etching conditions were controlled to investigate the SiO2/Si3N4 selective etching ability of the HF solution. The cross-sectional FE-SEM images visually showed that high SiO2 etching selectivity compared to Si3N4 was achieved. As a result, highly selective SiO2 etching without loss of Si3N4 was obtained by adjusting only the concentrations of HF and NH4F, without any special additives through the suggested SiO2 and Si3N4 etching kinetics.
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Romano, A., J. Vanhellemont, A. De Keersgieter, W. Vandervorst, J. R. Morante, and J. Van Landuyt. "A novel TEM technique for junction delineation in integrated circuits." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 4 (1990): 748–49. http://dx.doi.org/10.1017/s0424820100176873.
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Ion implantation is a well established technique to dope selectively prespecified regions of silicon substrates. It has the drawback that a thermal treatment is required to activate the dopant and to reconstruct the crystal lattice. This leads to dopant diffusion in depth and also laterally, when the implantation has been preformed through a patterned mask.In this paper two different approaches to determine the doping profile using chemical etching and TEM are presented. Cross-section specimens are prepared using a technique described elsewhere, followed by preferential etching.The first approach is well established and is based on the combined action of HF and HNO3.Low concentrations of HF are used to keep the etching rate low enough. Figure 1 shows a cross-section of a boron implanted and annealed sample which has been etched using the solution HF(40%):HNO3(65%)= 1:300 at 5°C for 80 seconds. The etching rate is proportional to the doping level, as shown in figure 2 and it can be observed that the lowest level which one can delineate with this solution is of the order of 1017cm−3, which is in agreement with the delineated level of figure 1, namely 6·1017 cm−3.
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Gablech, Imrich, Jan Brodský, Jan Pekárek, and Pavel Neužil. "Infinite Selectivity of Wet SiO2 Etching in Respect to Al." Micromachines 11, no. 4 (2020): 365. http://dx.doi.org/10.3390/mi11040365.
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We propose and demonstrate an unconventional method suitable for releasing microelectromechanical systems devices containing an Al layer by wet etching using SiO2 as a sacrificial layer. We used 48% HF solution in combination with 20% oleum to keep the HF solution water-free and thus to prevent attack of the Al layer, achieving an outstanding etch rate of thermally grown SiO2 of ≈1 µm·min−1. We also verified that this etching solution only minimally affected the Al layer, as the chip immersion for ≈9 min increased the Al layer sheet resistance by only ≈7.6%. The proposed etching method was performed in an ordinary fume hood in a polytetrafluorethylene beaker at elevated temperature of ≈70 °C using water bath on a hotplate. It allowed removal of the SiO2 sacrificial layer in the presence of Al without the necessity of handling highly toxic HF gas.
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Kuo, Chin-Guo, Cheng-Fu Yang, Mu-Jung Kao, et al. "An Analysis and Research on the Transmission Ratio of Dye Sensitized Solar Cell Photoelectrodes by Using Different Etching Process." International Journal of Photoenergy 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/151973.
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Classical photoelectrodes for Dye Sensitized Solar Cells (DSSCs) were fabricated by using the electrochemical method on the titanium (Ti) template, for that the fabrication process would influence the characteristics of the DSSCs. In this study, at first three different methods were used to etch Ti templates from 10 to 17 min, (1) polishing-chemical etching: Ti template was annealed at 450°C for 1 h, abraded using number 80 to 1500 SiC sheet, and then etched in a solution of 5% HF + 95% H2O; (2) electrochemical polishing-chemical etching: Ti template was annealed at 450°C for 1 h, electrolytic polishing with 42% CH3OH + 5% HClO4 + 53% HOCH2CH2OC4H9solution, and the chemical-etching in a solution of 5% HF + 95% H2O; (3) chemical etching: Ti template was etched in a solution of 5% HF + 95% H2O and annealed at 450°C for 1 h. When the etching time was changed from 10 to 17 min, the thicknesses of Ti templates decreased from 75.3 μm to 14.8 μm, depending on the etching method. After etching process, the TiO2nanotube arrays were fabricated as the photoelectrode of DSSCs by electrochemical process, in which the Ti as anode and platinum (Pt) as cathode. The electrolyte solution included C2H4(OH)2, NH4F, and deionized water. After annealing the grown TiO2nanotube arrays at 450°C for 3 h, we would show that the etching process had large effect on the structure and transmittance ratio of the TiO2nanotube arrays.
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Song, Chenfei, Bingjun Yu, Mian Wang, and Linmao Qian. "Rapid and maskless nanopatterning of aluminosilicate glass surface via friction-induced selective etching in HF solution." RSC Advances 5, no. 97 (2015): 79964–68. http://dx.doi.org/10.1039/c5ra13049b.
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A rapid and maskless nanofabrication method on glass was proposed, which consisted of scanning with a diamond tip and post-etching in HF solution. The masking effect on scan area is attributed to the formation of AlF<sub>3</sub>during etching.
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Wang, Wei, Li Juan Zhao, Ping Xin Song, and Ying Jiu Zhang. "Etching Volume Effect on the Morphology of Silicon Etched by Metal-Assisted Chemical Method." Applied Mechanics and Materials 217-219 (November 2012): 1141–45. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1141.
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Assisted by Ag nanoparticles, Si substrates were etched in aqueous solutions containing hydrofluoric acid (HF) and hydrogen peroxide (H2O2) with different volumes of etching solution. The etching morphology of Si wafers was found to be affected by the volumes. In etching solutions with smaller volume, the pores were created; in etching solutions with larger volume, the nanostructure composed of nanowires and nanopores (pores+wires nanostructure) were generated. In addition, the lengths of these Si nanostructures increased with the increase of the etching volume. Possible formation mechanism for this phenomenon was discussed.
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Liu, Ze Wen, Tian Ruo Zhang, Li Tian Liu, and Zhi Jian Li. "Realization of Silicon Nitride Template for Nanoimprint: A First Result." Solid State Phenomena 121-123 (March 2007): 669–72. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.669.
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A first result of realization of silicon nitride templates on 100mm silicon wafer as nanoinprint mold using simple wet etching method is reported in this paper. The process is based on traditional photolithograph and following buffer HF wet etching, which started from a p-type wafer with 400nm thermal silicon oxide, 200nm PECVD silicon nitride and 400nm PECVD silicon oxide sandwich layer. After patterning with lithography, the patterned resist is used as mask for the isotropic underlayer wet etching of silicon dioxide with buffer HF solution. Using the obtained nanosacle silicon dioxide lines as RIE dry etching mask, silicon nitride template of 100nm width with steep sidewalls is successfully realized.
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Zhao, Guo Dong, Xing Hua Zhu, You Yu, and Xiao Lin Zheng. "Optical Properties of Black Silicon Using the Combination Method of KOH and Gold-Assisted HF Etching." Advanced Materials Research 918 (April 2014): 42–46. http://dx.doi.org/10.4028/www.scientific.net/amr.918.42.
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A kind of hill-like black silicon have been designed and fabricated by using the combination method of KOH anisotropic etching and gold-assisted HF etching. Pillars array on the surface of a silicon sample was obtained by KOH etching with a SiNx film dots pattern used as a mask. The sample was then etched in the oxidant HF solution catalyzed by Au nanoparticles for 5 minutes. The etched sample appears dark black. This black silicon is orderly hill-like textures in micro-scale with density nanopores on them. It can suppress the reflection to less than 4% in wavelength range from 250nm to 1000nm, and to about 2.5% at the wave number of 2000-4000 cm-1. It also has high additional absorption in IR range.
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Lesa, A. D., I. Puspita, A. M. Hatta, F. Kurniawan, and S. Koentjoro. "The effect of immersion time on singlemode-tapered multimode-singlemode (STMS) fabrication using a chemical etching method." Journal of Physics: Conference Series 2274, no. 1 (2022): 012011. http://dx.doi.org/10.1088/1742-6596/2274/1/012011.
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Abstract Singlemode-Multimode-Singlemode (SMS) is one of the fiber optic sensor structures that is widely applied for many sensing applications. High sensitivity is the preferred characteristic of SMS fiber structure. In this paper, a tapered structure is introduced to the SMS fiber structure to increase its performance. The tapered structure is made by the etching method by immersing the SMS multimode fiber in hydrofluoric acid (HF) solution. The immersion time was varied 5, 10, 15 and 20 minutes. The diameter of the multimode fiber decreases with the longer immersion time, while the length does not change. The STMS transmission spectrum was measured to investigate its performance. The chemical etching method using HF solution for tapering the SMS fibers has great potential as a simple method to achieve a smaller radius without lengthening multimode fibers.
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ÖZCAN, MERVE, BİLGEHAN TUNCA, IPEK BILTAŞ, and TUNÇ TUKEN. "The Effect of Different Pre-Surface Finishing Method on the Aluminium Anodization of the 6XXX Series Alloy." Acta Metallurgica Slovaca 27, no. 4 (2021): 185–89. http://dx.doi.org/10.36547/ams.27.4.1109.
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In this study, the effect of different pre-surface finishing method on the aluminium anodization was investigated for AA 6063 alloy. Within the scope of pre-surface finishing method which is acidic solution concentrations and process time were determined. Acidic solution was determined by using hydrofluoric acid (HF) and nitric acid (HNO3). Also Gresoff LIM-5 LV chemical was used with different concentrations and process time for degreasing process. The etching effect of acidic solution on aluminium samples was investigated. The optimal etching behaviour was obtained with 1.0% concentration of HF and 3.2% concentration of HNO3 at 10 minutes process time. Also optimal surface properties were observed with 1.0% concentration of Gresoff LIM-5 LV at 12 minutes process time. Then anodic oxidation was performed by using 180 g / L sulfuric acid (H2SO4) and 18 volt (V). Surface morphology of the final aluminium profiles were examined with SEM analysis, Roughness, Gloss and Thickness tests.
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Yang, Rui, Gui Quan Jiang, Jun Ma, Shi Yan Han, and Jiu Yin Pang. "Preparation of Alumina Nanowires by Etched Method in Acid Solution." Key Engineering Materials 609-610 (April 2014): 370–74. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.370.
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Porous alumina films are obtained on aluminum piece by electrochemical method. In this work, we ues a kind of method for alumina nanowires by the alumina films. The result is showed with SEM. We study the effects of etching action in the dilute HF solution, and deduce the reason. We study catalyzed formaldehyde by the alumina nanowire supported titanium dioxide, results show that, the catalytic effect is better than activated carbon supported.
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Jin, Dahee, Ju-Myung Kim, Ran Yi, and Ji-Guang Zhang. "A New Approach to Synthesis of Porous Si Anode for Li-Ion Batteries Via Organic-Solvent Assisted Etching." ECS Meeting Abstracts MA2024-02, no. 5 (2024): 570. https://doi.org/10.1149/ma2024-025570mtgabs.
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Silicon (Si) has been regarded as a promising anode for Li-ion batteries due to its high theoretical capacity (4200 mAh/g) compared to graphite anode (372 mAh/g). However, it undergoes significant volume changes (~ 300%) during lithiation and delithiation, leading to particle pulverization and continuous electrolyte decomposition on Si surface, which hinders its practical application. The porous silicon obtained by wet etching method using hydrogen fluoride (HF) can accommodate the volume changes and improve the overall performance of silicon anodes. However, HF etching is highly corrosive, leading to the generation of excess heat and bubbling, lower yields, and difficult to scale-up. Furthermore, the water in etchant oxidizes the newly exposed Si, generating more SiOx, which also cause over-etching of Si and worsen electrochemical performance. Herein, we report an organic-solvent assistant etching process for Si anode. In this process, selected organic solvent were mixed with the HF etchant. When micron sized Si/SiOx powder was added to the solution, the organic solvent in the mixed solution will preferentially be absorbed on the surface of Si/SiOx powder and form a shield which can enable controlled etching of silicon oxide (SiOx) and prevent direct contact between water and newly etched Si surface. This method leads to controllable etching of Si and avoids bubbling/overheating, results in a higher Si yield. The maximum temperature during the etching process is less than ~30°C. The various process parameters, including etchant composition, stirring speed, and time have been optimized to maximize the yield and electrochemical performance of the Si anode. A Si-based anode with organic-solvent assisted etching process has demonstrated improved cycling performance in a Si||Li(Ni0.6Co0.2Mn0.2)O2 (NMC622) full cell. It also leads to low swelling in both particle and electrode levels required for the next generation of high-energy LIBs. Similar organic-solvent assisted etching process can also be used in safe-etching of a broad range of materials.
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Cao, D. T., C. Tuan-Anh, L. T. Quynh-Ngan, N. H. Anh, and Pham Thu Nga. "Fabrication of Porous Layer on the Nondoped Amorphous SiC Thin Film by Anodic Etching Method in HF/H2O/H2O2." Key Engineering Materials 495 (November 2011): 343–46. http://dx.doi.org/10.4028/www.scientific.net/kem.495.343.
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Due to the inertness of the intrinsic (nondoped) amorphous SiC (i-aSiC) material to the chemical impact, for making it porous by the electrochemical etching method, one must use the electrolyte solution with an appropriate composition. For this purpose we have found that besides the use of solutions containing surface activation agent (Triton X-100 for example), one can use also solutions containing oxidation agent. In this report we present the results obtained with electrolyte solution in which H2O2 plays the role of oxidation agent. Results showed that with appropriate ratio of components in the HF/H2O/H2O2 solution, we can manufacture a porous layer in the i-aSiC thin film with the porosity similar to the porosity of the porous layer obtained by etching in the HF/H2O/Triton X-100 solution with optimal composition. Thin film of i-aSiC material with porous surface layer can be used in different types of sensors.
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Bui, Pho Van, Kouji Inagaki, Yasuhisa Sano, Kazuto Yamauchi, and Yoshitada Morikawa. "Investigation of the Barrier Heights for Dissociative Adsorption of HF on SiC Surfaces in the Catalyst-Referred Etching Process." Materials Science Forum 778-780 (February 2014): 726–29. http://dx.doi.org/10.4028/www.scientific.net/msf.778-780.726.
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We have developed a novel abrasive-free planarization method, which we term catalyst-referred etching (CARE). In silicon carbide (SiC) CARE, Pt is used as a catalyst and HF solution is used as an etchant. CARE produces a crystallographically undamaged and smooth SiC surface. To understand the removal mechanism at the topmost surface of SiC in the CARE process, we performed first-principles reaction path simulations using the simulation tool for atom technology (STATE) program package. These calculations are based on the density functional theory within the generalized gradient approximation of Perdew et al. The barrier height of the dissociative adsorption of HF on a SiC surface was evaluated by the climbing image nudged elastic band method. We present simulation results for the initial stages of the etching process. The reaction barrier height for adsorption of the first HF is 1.2 eV.
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Zhang, Pei, Xiaoye Nan, Kexin Wang, et al. "A Facile Etching Route for Preparing Ti3C2 MXene with Enhanced Electrochemical Performance in Silver Nitrate Solution." Journal of The Electrochemical Society 169, no. 4 (2022): 043506. http://dx.doi.org/10.1149/1945-7111/ac62c2.
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Two-dimensional Ti3C2 MXene is a promising electrode material for high-capacity supercapacitor, which is normally prepared by selective etching of the Al layer from ternary carbide Ti3AlC2 MAX phase using HF acid solution. Here a distinct etching method using a little HF acid is reported. Ti3C2 MXene decorated with Ag nanoparticles are synthesized via a chemical replacement reaction with AgNO3 solution at room temperature and then evaluated as working electrodes. Due to the synergistic effect between Ag and Ti3C2 matrix, the resulting composite of the 10 wt% AgNO3 treated sample (Ag-10) exhibits higher specific capacitance of 779.5 F g−1 at the scan rate of 5 mV s−1 in 6 M KOH electrolyte solution and shows good cycling stability with capacitance retaining 95% after 5000-cycles. This work also shows the possibility of using other metallic cations with higher redox potential to prepare high performance MXenes for supercapacitor materials.
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Hadjersi, T., N. Gabouze, A. Ababou, et al. "Metal-Assisted Chemical Etching of Multicrystalline Silicon in HF/ Na2S2O8 Produces Porous Silicon." Materials Science Forum 480-481 (March 2005): 139–44. http://dx.doi.org/10.4028/www.scientific.net/msf.480-481.139.
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A new metal-assisted chemical etching method using Na2S2O8 as an oxidant is proposed to form a porous layer on a multicrystalline silicon (mc-Si). This method does not need an external bias and enables formation of uniform porous silicon layers, more rapidly than the conventional stain etching method. A thin layer of Pd is deposited on the mc-Si surface prior to immersion in a solution of HF and Na2S2O8. The characterisations of etched layer formed by this method as a function of etching time were investigated by scanning electron microscopy, X-ray diffraction (XRD), Energy-dispersive X-ray (EDX) and reflectance spectroscopy. It shows that the surface is porous and the etching is independent of grain orientation. In addition, reflectance measurements made with a variety of etching conditions show a lowering of the reflectance from 25 % to 6 % measured with respect to the bare as-cut substrate. However, this result can be improved by changing the experimental conditions (concentration, time, temperature, …).
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Nara, Takayuki, Kouki Oku, Hirofumi Fukai, Hideki Hatagouchi та Yasushiro Nishioka. "Silicon Microfabrication Processes Including Anodic Bonding of Extremely Thin (60 μm –Thick) Silicon on Glass". Advanced Materials Research 306-307 (серпень 2011): 180–84. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.180.
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A new silicon MEMS process has been proposed utilizing anodic bonding of an extremely thin silicon film (60 m) on a glass substrate, followed by photo lithographically defining micro spring structures on the silicon film and dry etching the silicon film using an inductively coupled plasma (ICP) dry etcher. After that, the underneath glass was selectively etched off using a hydrofluoric (HF) solution to release the micro spring. This technique was successfully applied to a micro vibration detection sensor with the silicon microspring with a cross section of 10 m x 60 m with a length longer than 500 m.
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Guseva, O. S., D. V. Kozlov, A. S. Korpukhin, I. P. Smirnov, and P. A. Andreev. "Application of a Femtosecond Laser in the Fabrication fused Silica Sensing Elements for MEMS Accelerometers." Nano- i Mikrosistemnaya Tehnika 24, no. 1 (2022): 3–8. http://dx.doi.org/10.17587/nmst.24.3-8.
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A group method of manufacturing quartz sensing elements of MEMS Q-flex type accelerometers is known, which is based on sequential liquid and plasma chemical etching in fluorinated plasma. In order to reduce the defects of the final products, labor costs for their manufacture and to obtain a rectangular etching profile of through holes in the section of the sensing element, an alternative technology for forming holes has been developed. The technology is thus the laser radiation pretreatment of fused silica glass with ultrashort pulse duration (about hundreds of femtoseconds) for the entire thickness of the substrate and subsequent liquid etching holes. The conducted studies revealed a local increase in the etching rate of irradiated section of fused silica glass during liquid etching with hydrofluoric acid or alkaline solution. The influence of the etching solution concentration on the change in the etching rate and the roughness of quartz is analyzed. The technology is universal and it can be used for high-precision volumetric processing of product formed from fused silica glass up to 4 mm thick.
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Wang, He, Chunlan Zhou, and Wenjing Wang. "A non-metallic additive for diamond-wire-sawn multi-crystalline silicon texturing." E3S Web of Conferences 252 (2021): 02067. http://dx.doi.org/10.1051/e3sconf/202125202067.
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Diamond-wire-sawn (DWS) technology has been widely used in the photovoltaic industry. When using the HF/HNO3/H2O acid etching solution for texturing of DWS multi-crystalline silicon(mc-Si), the aid of additive is required to improve the reactivity of the mc-Si surface in the acid texturing solution. It also needs to enhance the nucleation and uniform growth of the texturing surface. This paper proposes a non-metallic additive for DWS mc-Si texturing. Sodium polyacrylate is added to the HF/HNO3/H2O acid etching solution to reduce the reflectance of DWS mc-Si and improve surface morphology. Compared to the textured wafers without additive, the surface of the wafers using this method is uniformly distributed with pits whose size is 0.5 μm×1 μm. And the weighted average reflectance of the textured wafers can be reduced from 33.32% to 23.9% in the wavelength range of 350–1100 nm, with the lowest reflectance of 19.8% reached at 950 nm. It shows a promising application prospect.
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Burnat, B., M. Parchańska-Kowalik, and L. Klimek. "The Influence of Chemical Surface Treatment on the Corrosion Resistance of Titanium Castings Used in Dental Prosthetics." Archives of Foundry Engineering 14, no. 3 (2014): 11–16. http://dx.doi.org/10.2478/afe-2014-0052.
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Abstract Air abrasion process is used for cleaning casting surface of prosthetic components, and to prepare the surface of these elements for the application of veneering items. Its side effect, however, is that abrasive particles are embedded in the treated surface, which can be up to 30% of the surface and it constitutes the side effect of this procedure. Such a significant participation of foreign material can not be indifferent to the properties of the surface. Embedded particles can be the place of stress concentration causing cracking of ceramics, and may deteriorate corrosion resistance by forming corrosive microlinks. In the latter cases, it would be advisable to remove elements embedded into the surface. The simplest method is chemical etching or electrochemical one. Nevertheless, these procedures should not significantly change the parameters of the surface. Among many possible reagents only a few fulfills all the above conditions. In addition, processing should not impair corrosion resistance of titanium, which is one of the most important factors determining its use as a prosthetic restoration in the mouth. The study presented results of corrosion resistance of titanium used to make prosthetic components by means of casting method, which were subjected to chemical processing designed to remove the embedded abrasive particles. The aim of the study was to investigate whether etching with selected reagents affects the corrosion resistance of titanium castings. For etching the following reagents were used: 30% HNO3 + 3% HF + H2O, HNO3+ HF+ glycerol (1:2:3), 4% HF in H2O2, 4% HF in H2O, with a control sandblasted sample, not subjected to etching. Tests demonstrated that the etching affected corrosion properties of test samples, in each case the reduction of the corrosion potential occurred - possibly due to the removal of particles of Al2O3 from the surface and activation of the surface. None of the samples underwent pitting corrosion as a result of polarization to 9 V. Values of the polarization resistance, and potentiodynamic characteristics indicated that the best corrosion resistance exhibited the samples after etching in a mixture of 4% solution of HF in H2O2. They showed very good passivation of the surface.
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Jafarov, M. A., E. F. Nasirov, A. H. Kazımzade, and S. A. Jahangirova. "Synthesis and characterization of nanoscale material ZnS in porous silicon by chemical method." Chalcogenide Letters 18, no. 12 (2021): 791–95. http://dx.doi.org/10.15251/cl.2021.1812.791.
Full textAbstract:
ZnS nanoparticles were obtained by chemical precipitation from a solution (CPD) on porous silicon (PS) prepared by chemical etching of an n-type silicon wafer (100) with a solution of fluoride acid (HF) at room temperature. A thorough study was carried out using structural methods such as atomic force and scanning electron microscopy (AFM, SEM). The optical properties of the fabricated ZnS-PS materials were investigated and it was shown that the synthesis of nanoscaleZnS particles in silicon pores revealed new photoluminescence (PL) characteristics, such as bright and stable radiation in the visible part of the spectrum, even at room temperature.
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Abdulkadir, Auwal, and Mohd Zamir Pakhuruddin. "Effects of Hydrogen Peroxide Concentration on Properties of Black Silicon Fabricated by Two-Step Silver-Assisted Wet Chemical Etching for Photovoltaics." Iraqi Journal of Physics (IJP) 20, no. 2 (2022): 11–25. http://dx.doi.org/10.30723/ijp.v20i2.985.
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Crystalline silicon (c-Si) has low optical absorption due to its high surface reflection of incident light. Nanotexturing of c-Si which produces black silicon (b-Si) offers a promising solution. In this work, effect of H2O2 concentrations towards surface morphological and optical properties of b-Si fabricated by two-step silver-assisted wet chemical etching (Ag-based two-step MACE) for potential photovoltaic (PV) applications is presented. The method involves a 30 s deposition of silver nanoparticles (Ag NPs) in an aqueous solution of AgNO3:HF (5:6) and an optimized etching in HF:H2O2:DI H2O solution under 0.62 M, 1.85 M, 2.47 M, and 3.7 M concentrations of H2O2 at 5 M HF. On the b-Si, nanowires with 250-950 nm heights and an average diameter of 150-280 nm are obtained. Low concentrations of H2O2 result in denser nanowires with an average length of 900-950 nm and diameters of about 150-190 nm. The b-Si exhibit outstanding broadband antireflection due to the refractive index grading effect represented as WAR within the 300-1100 nm wavelength region. B-Si obtained after etching in a solution with 0.62 M concentration of H2O2, demonstrate WAR of 7.5%. WAR of 7.5% results in an absorption of up to 95.5 % at a wavelength of 600 nm. The enhanced broadband light absorption yields maximum potential short-circuit current density (Jsc(max)) of up to 38.2 mA/cm2, or 45.2% enhancement compared to the planar c-Si reference.
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Hwang, Ki‐Hwan, Sang‐Hun Nam, Won Suk Jung, Yong Min Lee, Hee‐Su Yang, and Jin‐Hyo Boo. "Wet Chemical Etching of Al‐doped ZnO Film Deposited by RF Magnetron Sputtering Method on Textured Glass Substrate for Energy Application#." Bulletin of the Korean Chemical Society 36, no. 3 (2015): 850–54. http://dx.doi.org/10.1002/bkcs.10159.
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The etching of glasses in aqueous hydrofluoric acid (HF) solutions is applied in many technological fields. Particularly, the textured transparent conductive oxide materials on the glass substrate etched by HF were used to improve the current density of solar cells. In this study, the textured glass substrate has been etched by solution and the Al‐doped ZnO (AZO) thin films have been prepared on this textured glass substrates by RF magnetron sputtering method. After the AZO film deposition, the surface of AZO has been etched by hydrochloric acid with different concentration and etching time. Etched AZO thin films had higher haze ratio and sheet resistance than bare AZO glass. Increases in the root‐mean‐square surface roughness of AZO films enhanced from 53.78 to 84.46 nm the haze ratio in above 700 nm wavelength. Our process could be applicable in texturing glass and etching AZO surface to fabricate solar cell in industrial scale. We also carried out fabricating an organic solar‐cell device. Energy conversion efficiency improvement of 123% was obtained with textured AZO‐based solar‐cell device compared with that of nontextured solar‐cell device.
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Ou, Wei Ying, Lei Zhao, Zhao Chen Li, Hong Wei Diao, and Wen Jing Wang. "Optimization Study on Preparation of Macroporous Silicon on P-Type Silicon Substrate by Electrochemical Etching." Advanced Materials Research 488-489 (March 2012): 1343–47. http://dx.doi.org/10.4028/www.scientific.net/amr.488-489.1343.
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Low cost electrochemical etching method was utilized to prepare macroporous silicon on p-type silicon substrate in dilute HF solution. By optimizing the substrate resistivity, the etching current density, and the etching time, excellent macroporous silicon was obtained on 15 Ω•cm p-type silicon substrate with the pore diameter of about 2 μm, the pore depth of about 30 μm, and the surface pore density up to ~107/cm2. Such macroporous silicon gave out an excellent antireflective performance with the reflectance lower than 4% in a wide spectral range of 400-1000 nm. The low reflectance combined with the deep pore morphology provides an attractive potential to fabricate radial p-n junction solar cells on such macroporous silicon.
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Bui, Pho Van, Kouji Inagaki, Yasuhisa Sano, Kazuto Yamauchi, and Yoshitada Morikawa. "First-Principles Study of Reaction Process of SiC and HF Molecules in Catalyst-Referred Etching." Key Engineering Materials 523-524 (November 2012): 173–77. http://dx.doi.org/10.4028/www.scientific.net/kem.523-524.173.
Full textAbstract:
We have developed a novel abrasive-free planarization method, which we term catalyst-referred etching (CARE). In SiC CARE, Pt is used as a catalyst and HF solution is used as an etchant. CARE produces a crystallographically undamaged and smooth SiC surface. To understand the removal mechanism at the topmost surface of SiC in the CARE process, we performed first-principles reaction path simulations using the Simulation Tool for Atom Technology (STATE) program package. These calculations are based on the density functional theory within the generalized gradient approximation of Perdew et al. The barrier height is evaluated by the climbing image nudged elastic band method. We present simulation results for the initial stages of the etching process. The reaction barrier heights for the adsorption of HF molecules on the first, second, and third Si–C bonds at the edge of the topmost Si-face are 1.8, 1.9, and 1.2 eV, respectively. These barrier heights are reasonably small for a consideration of effect of the Pt catalyst.
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Amjad Hussein Jassem. "Effect of photo chemical etching and electro chemical etching on the topography of porous silicon wafers surfaces." Tikrit Journal of Pure Science 24, no. 4 (2019): 52–56. http://dx.doi.org/10.25130/tjps.v24i4.399.
Full textAbstract:
In This research we study the effect of photo chemical etching and electrochemical etching on topography of porous silicon surfaces, the results showed that photo chemical etching produced roughness silicon layer which can have thickness be less of porous silicon layer which is produced by electro chemical etching When all the wafers have same etching time and hydrofluoric solution (HF) concentration, the wafers have same resistance (10 Ω.cm).
 Also the results showed the roughness of porous silicon layers produced by electro chemical method which is bigger than the roughness of porous silicon layers produced by photo chemical method and the results of roughness of porous silicon layers, Pore diameter and porous layer thickness were produced by electro chemical method (1.55(µm) ((0.99(µm)) and ((1.21(µm) respectively), the results of roughness of porous silicon layers, Pore diameter and porous layer thickness were produced by photo chemical method 0.63)) nm -1.55)) (µm) ),so the (84.9 (nm)- and (3.94(nm) respectively .
 This is reinforces because of using the electro chemical to etching the wafer surf ace of bulk silicon and changing it to roughness silicon surface be share in success of many practicalities.
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Yasuda, Kohei, Nobuya Mineyuki, Kohei Sano, Yasuo Hayashi, and Takayuki Homma. "Microfabrication of Highly Robust Superhydrophobic Glass Surfaces Via Combined Thermal Poling and HF Gas Etching." ECS Meeting Abstracts MA2024-02, no. 16 (2024): 1648. https://doi.org/10.1149/ma2024-02161648mtgabs.
Full textAbstract:
Superhydrophobic glass affords a clear view by preventing the adhesion of raindrops and dirt. This type of glass can be used in automotive windows, sensor covers for automatic driving, solar panels, and building windows. A superhydrophobic surface has a water contact angle greater than 150° and is fabricated by combining micro- to nanoscale structures with low-surface energy coating materials. In the previous study [1], we demonstrated that the transparent superhydrophobic glass can be efficiently produced through HF gas etching. The robustness of its superhydrophobic surface is the most challenging issue in the practical application of the superhydrophobic glass. The recent breakthrough, namely, the development of superhydrophobic surfaces with “armor structures” [2], addresses this issue for conventional superhydrophobic surfaces containing nanostructures that would be easily destroyed by abrasion. The armor structures protect the fragile superhydrophobic nanostructures, resulting in highly robust abrasion resistance. In the previous study, the armor structures were fabricated using molding methods that impose strict limitations on the shapes that can be formed. A common microfabrication technique, which combines photolithography and reactive ion etching (RIE), can be applied to glass surfaces. This method allows for the formation of any desired shape on the glass surface. However, this method involves vacuum processes that require masks, resulting in extremely low productivity. Compared to electronic components, for which this technique is typically used, glass has a larger area and lower unit cost. The low production efficiency of the technique would therefore hinder its applicability. In this study, we developed a unique microfabrication method that combines thermal poling and HF gas etching. In thermal poling, heated glass is sandwiched between electrodes, and a high voltage is applied to transfer alkali metal ions from the anode-side surface of the glass [3]. Microstructures formed on the surface of the anode used for thermal poling are transferred onto the glass surface as alkali metal-deficient regions. Subsequently, etching the glass facilitates the formation of these shapes on the glass surface owing to the difference in etching rates. At this stage, traditional solution-etching fabricated steps on the nanometer scale; larger steps on the microscale remain to be formed. We fabricated the steps on the micrometer scale via HF gas etching, which presents a large difference in the etching rate between the alkali-metal-deficient layer and the normal surface. Figure 1 presents the results of glass microfabrication using thermal poling and HF gas etching. Circular shapes with diameters of 2.5, 5, 10, 20, and 40 µm were created for the proof of concept. A glassy carbon microfabricated via RIE was used as the anode. For thermal poling, a voltage of 300 V was applied to the glass heated to 450 °C for 5 min. HF gas etching was performed at 500 °C with a small amount of HF gas for a few seconds. A highly robust superhydrophobic glass surface was thus fabricated. The surface produced using the proposed method successfully endured 1000 abrasion cycles, while that produced using the conventional method lost its superhydrophobicity after ten abrasion cycles. [1] K. Yasuda, Y. Hayashi, and T. Homma, ACS Omega, 9, 12204–12210 (2024). [2] D. Wang et al., Nature, 582, 55–59 (2020). [3] S. Ikeda, K. Uraji, T. Suzuki, K. Yamamoto, and J. Nishii, J. Non-Cryst. Solids, 453, 103–107 (2016). Figure 1
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Rosli, Aimi Bazilah, Sukreen Hana Herman, Noor Hazwani Nordin, Nur Sa'adah Mohd Sauki, Shafinaz Sobihana Shariffudin, and Mohamad Rusop Mahmood. "Effect of Seed Layer Morphology on the Growth of Zinc Oxide Nanotetrapods by Thermal Chemical Vapour Deposition Method." Advanced Materials Research 832 (November 2013): 429–33. http://dx.doi.org/10.4028/www.scientific.net/amr.832.429.
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We investigated the growth of zinc oxide (ZnO) nanotetrapods on a crystallized ZnO seed layer. The seed layer was deposited by RF magnetron sputtering and etched by HF solution before the deposition of ZnO nanotetrapods by thermal chemical vapor deposition. The HF etching was done to roughen the seed layer surface to facilitate the nucleation sites for the nanostructures growth. We found that the shapes of the nanostructures on the HF-etched seed layers and those on un-etched seed layer are different, in which the nanostructures on the etched layers are in the form of plates with needles grown at the edge, whereas the nanostructures on the un-etched layers are in the shape of typical nanotetrapods. This is believed to be the result of different growth mechanisms associated with the different conditions of the growth surface.
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Iatsunskyi, Igor, Valentin Smyntyna, Nykolai Pavlenko, and Olga Sviridova. "Peculiarities of Photoluminescence in Porous Silicon Prepared by Metal-Assisted Chemical Etching." ISRN Optics 2012 (November 1, 2012): 1–6. http://dx.doi.org/10.5402/2012/958412.
Full textAbstract:
Photoluminescent (PL) porous layers were formed on p-type silicon by a metal-assisted chemical etching method using H2O2 as an oxidizing agent. Silver particles were deposited on the (100) Si surface prior to immersion in a solution of HF and H2O2. The morphology of the porous silicon (PS) layer formed by this method was investigated by atomic force microscopy (AFM). Depending on the metal-assisted chemical etching conditions, the macro- or microporous structures could be formed. Luminescence from metal-assisted chemically etched layers was measured. It was found that the PL intensity increases with increasing etching time. This behaviour is attributed to increase of the density of the silicon nanostructure. It was found the shift of PL peak to a green region with increasing of deposition time can be attributed to the change in porous morphology. Finally, the PL spectra of samples formed by high concentrated solution of AgNO3 showed two narrow peaks of emission at 520 and 550 nm. These peaks can be attributed to formation of AgF and AgF2 on a silicon surface.
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Yu, Qihui, Henk-Willem Veltkamp, Remco J. Wiegerink, and Joost C. Lötters. "Fabrication of Buried Microchannels with Almost Circular Cross-Section Using HNA Wet Etching." Micromachines 15, no. 10 (2024): 1230. http://dx.doi.org/10.3390/mi15101230.
Full textAbstract:
In this paper, a novel fabrication process for the realization of large, suspended microfluidic channels is presented. The method is based on Buried Channel Technology and uses a mixture of HF, HNO3, and water etchant, which has high selectivity between the silicon substrate and the silicon-rich silicon nitride mask material. Metal electrodes for actuation and read-out are integrated into the fabrication process. The microfluidic channels are released from the silicon substrate to allow the vibrational movement needed for the application. The resulting microfluidic channels have a near-circular cross-section, with a diameter up to 300m and a channel wall thickness of 1.5m. The structure of a micro-Coriolis mass-flow and density sensor is fabricated with this process as an example of a possible application.
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Jassem, Amjad Hussein. "Effect of photo chemical etching and electro chemical etching on the topography of porous silicon wafers surfaces." Tikrit Journal of Pure Science 24, no. 4 (2019): 52. http://dx.doi.org/10.25130/j.v24i4.845.
Full textAbstract:
In This research we study the effect of photo chemical etching and electrochemical etching on topography of porous silicon surfaces, the results showed that photo chemical etching produced roughness silicon layer which can have thickness be less of porous silicon layer which is produced by electro chemical etching When all the wafers have same etching time and hydrofluoric solution (HF) concentration, the wafers have same resistance (10 Ω.cm).
 Also the results showed the roughness of porous silicon layers produced by electro chemical method which is bigger than the roughness of porous silicon layers produced by photo chemical method and the results of roughness of porous silicon layers, Pore diameter and porous layer thickness were produced by electro chemical method (1.55(µm) ((0.99(µm)) and ((1.21(µm) respectively), the results of roughness of porous silicon layers, Pore diameter and porous layer thickness were produced by photo chemical method 0.63)) nm -1.55)) (µm) ),so the (84.9 (nm)- and (3.94(nm) respectively .
 This is reinforces because of using the electro chemical to etching the wafer surf ace of bulk silicon and changing it to roughness silicon surface be share in success of many practicalities.
 
 http://dx.doi.org/10.25130/tjps.24.2019.072
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Jiang, Tingxue, Haitao Wang, Xiaobing Bian, Daobing Wang, Jun Zhou, and Bo Yu. "Numerical Simulation on Hydrofracture Propagation in Fractured-Vuggy Unconventional Reservoirs." Geofluids 2022 (October 10, 2022): 1–32. http://dx.doi.org/10.1155/2022/8542453.
Full textAbstract:
The unconventional reservoirs such as carbonate formation develops complex and diverse storage space structures, and it is composed of large-scale cavity, dissolved vug, and fractures. The carbonate reservoir is highly heterogeneous. Acid fracturing of carbonate reservoir is completed through the complex mechanical mechanism of interaction between vug and hydraulic fracture (HF). We use the equivalent method of reducing the rock strength by acid etching and serious fluid leakoff during interaction of HF and vug to establish a finite element (FE) model of HF propagation during acid fracturing in the fractured-vuggy carbonate reservoir. The model considers the effect of serious fluid leakoff during interaction between HF and vug, mechanism of interaction between HFs and the fracture-vug system, and change in acid etching intensity. Then, we carry out numerical simulation on impacts of injection rate, fluid viscosity, leakoff behavior in fractures and vugs, and natural fracture (NF) approaching angle on HF propagation in acid fracturing and compare the characteristics of injection pressure, fracture pressure, and HF size. It is suggested that the acid fracturing treatment should be operated by increasing the acid solution viscosity to reduce fluid leakoff, injecting fracturing fluid and acid fluid alternatively, increasing injection rate, and injecting fibers and ceramics when small pressure drop occurs during the HF interacts with the fracture-vug. When a large pressure drop occurs, it is suggested that the middle-low viscosity acid be injected at a low rate to etch the carbonate rock and enhance the fracture conductivity. HF propagates under higher pressure when the NF approaching angle is smaller.
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Sun, Jie, Yan Zuo, Runguang Sun, and Lang Zhou. "Solar Cells Produced by Diamond Wire Sawn Multicrystalline Silicon Wafer by Using Additive-Assisted Acidic Texturization." Advances in Materials Science and Engineering 2022 (June 8, 2022): 1–8. http://dx.doi.org/10.1155/2022/7869901.
Full textAbstract:
A novel additive-assisted acidic etching method is proposed to improve the etched morphology of the diamond wire sawn (DWS)-processed multicrystalline silicon (mc-Si) wafers. The proposed etching technique is a cost-effective method for surface texturization of DWS-processed mc-Si wafers, which can be used for large-scale production of Si-based solar cells. Moreover, the mechanism of additive-assisted etching is explained by decoupling the roles of surfactants and etching inhibitors. The additive-assisted etching of DWS-processed mc-Si wafers resulted in different morphology to the slurry wire sawn (SWS)-processed mc-Si wafers under optimized etching conditions. It has been observed that the etched morphology and reflectivity of DWS-processed mc-Si wafers are significantly influenced by the ratio of hydrofluoric acid (HF): nitric acid (HNO3) solution. High-quality etching morphologies have been obtained. Therefore, high-power conversion efficiency of 19.0% and open-circuit voltage (Voc) of 0.6386 V have been demonstrated by additive-textured DWS-processed Si-based solar cells. The improved power conversion efficiency and Voc can be ascribed to the reduced defect area of the wafer surface. In summary, the proposed additive-assisted acidic etching is an effective strategy to obtain the desired surface texturization of DWS-processed Si wafers for high-performance solar cell applications.
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Thahe, Asad, Hazri Bakhtiar, Noriah Bidin, et al. "Morphology and luminescence of photo-electrochemically synthesized porous silicon: Influence of varying current density." Malaysian Journal of Fundamental and Applied Sciences 13, no. 4 (2017): 708–10. http://dx.doi.org/10.11113/mjfas.v0n0.538.
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Achieving high quality porous silicon (PSi) materials with desired porosity remains challenging. Three good qualities of PSi samples are prepared by Photo electro-chemically etching a piece of n-type Si inside the solution of 20 M HF, 10 M C2H5OH and 10 M H2O2 at fixed etching time duration (30 min) and varying current density (15 mA/cm2, 30 mA/cm2 and 45 mA/cm2). As-prepared sample morphologies are characterized via scanning electron microscopy (SEM) and atomic force microscopy (AFM). The gravimetric method is used to estimate the thickness and porosity of the prepared samples. Current density (etching time) dependent morphologies, electronic bandgap and room temperature photoluminescence (PL) properties of such PSi nanostructures are evaluated. These PSi structures revealed enhanced rectifying characteristics with increasing current density.
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Králik, Martin, Stanislav Jurečka, and Emil Pinčík. "Thickness and tensile stress determination of black silicon layers by spectral reflectance and Raman scattering." Journal of Electrical Engineering 70, no. 7 (2019): 51–57. http://dx.doi.org/10.2478/jee-2019-0041.
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Abstract In this work black silicon (b-Si) samples were prepared by anodic (electrochemical) etching of p-type silicon substrate in solution of hydrofluoric acid (HF). We studied influence of anodic etching conditions (etching time, electrical potential and current) on the spectral reflectance and Raman scattering spectra. Optical properties of b-Si structures were experimentally studied by UV-VIS (AvaSpec-2048) and Raman (Thermo DXR Raman) spectrometers. B-Si layer thickness of formed substrate were determined by using SCOUT software. Effective medium approximation theory (Looyenga) was used in construction of the reflectance model. Influence of the deformation of crystal lattice introduced during the substrate etching was studied by Raman scattering method. Teoretical model of the 1st order Raman scattering profile was constructed by using pseudo-Voigt function and the profile parameters were extracted. The values of biaxial tensile stress were estimated by using optimized Raman profile parameters.
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Chiang, Chun Ling, C. M. Cheng, J. H. Liao, et al. "Deposition Wet-Etching Deposition (DWD) Method for Polysilicon Gate Fill-In at Flash Memory." Solid State Phenomena 187 (April 2012): 49–52. http://dx.doi.org/10.4028/www.scientific.net/ssp.187.49.
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The present study aims at polysilicon material fill-in at re-entrant profile at flash memory product. The void was observed after polysilicon fill-in. In order to prevent the void formation, the multi-step process of deposition wet-etching deposition (DWD) method was evaluated. The DWD method is found to play beneficial roles in achieving void-free in the floating gate. The high concentration of NH4OH in APM was choosing for wet etching solution. Scanned electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to measure the polysilicon thickness and cross-section profile of device.
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Galaly, Ahmed Rida, Farouk Fahmy Elakshar, and Mohamed Atta Khedr. "Study of the Etching Processes of Si [1 0 0] Wafer Using Ultra Low Frequency Plasma." Materials Science Forum 756 (May 2013): 143–50. http://dx.doi.org/10.4028/www.scientific.net/msf.756.143.
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The etching processes of Si [1 0 0] wafer have been studied using two different methods; namely the wet chemical etching method, using HNO3-HF-CH3COOH solution, and the Ultra Low Frequency Plasma (ULFP) method at (1KHz). Ion etching using inert gas only (e.g., argon gas), and ion chemical etching using an active gas (beside the inert gas) such as oxygen techniques were used. Calculations of the different parameters produced by chemical etching and plasma etching for silicon wafer (sample) such as ( hole depth, hole width and etching rate) were investigated using the images of Optical Scanning microscope (OSM) and Joel Scanning microscope (JSM). The formed hole width (ω) increases by increasing the exposure time of the sample in the different types of etching. Values of the hole width were in the range of 2- 7 µm during exposure times of (30 to 100 min). The sample growth exponent constant was about ( 0.0707 and 0.0537 µm/min ) .Hole has depths in the range of( 0.5 to 3 µm) in time of (30 to 100 min).The average distances between the holes were decreased by increasing the exposure time from (14 to 4 µm) in the time range of (30 – 100 min). The rates of etching were ranged from (0.0226 to 0.0448 µm/ min) either for dry or wet etching. Normal 0 21 false false false MS X-NONE X-NONE The etching processes of Si [1 0 0] wafer have been studied using two different methods; namely wet chemical etching method, using HNO3-HF-CH3COOH solution, and Ultra Low Frequency Plasma (ULFP) method at (1KHz). Ion etching used inert gas only (e.g., argon gas) while ion chemical etching used an active gas (beside the inert gas) such as oxygen techniques were used. Calculations of the different parameters produced by chemical etching and plasma etching for silicon wafer (sample) such as ( hole depth, hole width and etching rate) were investigated using the images of Optical Scanning Microscope (OSM) and Joel Scanning Microscope (JSM). The formed hole width (ω) increased by increasing the exposure time of the sample in the different types of etching. Values of the hole width were in the range of 2- 7 µm during exposure times of (30 to 100 min). The sample growth exponent constant was about (0.0707 and 0.0537 µm/ min). Hole has depths in the range of( 0.5 to 3 µm) in time of (30 to 100 min).The average distances between the holes were decreased by increasing the exposure time from (14 to 4 µm) in the time range of (30 – 100 min). The rates of etching were ranged from (0.0226 to 0.0448 µm/ min) either for dry or wet etching. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}
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Cheng, C. W., J. S. Chen, P. X. Lee, and C. W. Chien. "Microfabrication of Photosensitive Glass by Femtosecond Laser Direct Writing." Advanced Materials Research 126-128 (August 2010): 394–400. http://dx.doi.org/10.4028/www.scientific.net/amr.126-128.394.
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In this study, a method for the fabrication of microstructures on the surface and inside photosensitive glass (Foturan glass) by femtosecond laser-induced modification was developed. This technique was followed by heat treatment to crystallize the modified area, and the specimen was then placed in an HF acid solution for chemical etching. The fabricated microstructures were observed using scanning electron microscopy (SEM). Two examples: (a) a U-shaped microchannel and (b) an arc-type microchannel formed inside glass are presented.
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Khaskhoussi, Amani, Luigi Calabrese, and Edoardo Proverbio. "An Easy Approach for Obtaining Superhydrophobic Surfaces and their Applications." Key Engineering Materials 813 (July 2019): 37–42. http://dx.doi.org/10.4028/www.scientific.net/kem.813.37.
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Three different methods were used to obtain nature-inspired superhydrophobic surfaces on aluminum alloys: short-term treatment with boiling water, HF/HCl and HNO3/HCl concentrated solution etching. Afterwards a thin octadecylsilane film was deposited on all pre-treated surfaces. The surface morphology analysis showed that each method allow to obtain a specific dual nano/micro-structure. The corresponding water contact angles ranged from 160° to nearly 180°. The adhesion force between the water droplets and superhydrophobic surfaces were evaluated. The specimen etched with HF/HCl acid mixture solution showed the lowest adhesion. However, the boiling water treatment sample was characterized by the highest adhesion. Furthermore, the relationship between hydrophobic behavior and surface morphology was discussed compressively. In addition, the electrochemical measurements show that the different superhydrophobic surfaces have an excellent anti-corrosion performance evidencing promising results suitable to obtain large-scale nature-inspired superhydrophobic surfaces for several industrial applications.
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Chen, Lan Li, Hai Hong Wang, Ming Ji Shi, Sheng Zhao Wang, and Wen Fang Si. "The Preparation of p-PS and its Photoluminescence Properties." Key Engineering Materials 538 (January 2013): 81–84. http://dx.doi.org/10.4028/www.scientific.net/kem.538.81.
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In this research, p-type porous silicon was successfully fabricated with a typical electrochemical etching method. The mixed solution of HF and absolute ethyl alcohol with different volume ratio was used as the electrolyte in this experiment. The anodic current density was 20 mA/cm2～60 mA/cm2. The luminous intensity of the PS samples increased with the increasing of the current density, the peaks of PL first red shift (from 692.1nm to 727.9nm) then blue shift (from 727.9nm to719.6nm). With the increasing of the concentration of HF, PS luminous intensity gradually decreases, and the peaks of PL gradually occurs red shift. And possible mechanisms of the growth and the photoluminescence of porous silicon were proposed to explain the experimental result．
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Abd Rahim, Alhan Farhanah, Mohamad Syarizal Abdullah, Ainorkhilah Mahmood, Nihad K. Ali, and Musa Mohamed Zahidi. "Quantum Confinement of Integrated Pulse Electrochemical Etching of Porous Silicon for Metal Semiconductor Metal Photodetector." Materials Science Forum 846 (March 2016): 245–55. http://dx.doi.org/10.4028/www.scientific.net/msf.846.245.
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Porous silicon (PS) was successfully synthesized via novel integrated pulsed electrochemical etching of an n-type (100) silicon (Si) substrate under various condition. The PS was etched using hydrofluoric acid (HF) based solution and the porosity was optimized by introducing electroless chemical etching process prior to photo electrochemical (PEC) anodization. In the electroless etching, a delay time (TD) of 2 min was applied. After that a cycle time (T) and pause time () of pulsed current were supplied throughout the 30 min PEC etching process. As grown Si and PS through conventional direct current (DC) anodization were also included for comparison. The result obtained showed that applying delay time helps to improve the uniformity and density of the porous structures. AFM indicated that the roughness of the Si increases as the dissolution of the Si occurred. Raman spectroscopy showed that an improvement in the crystalline quality of PS under pulse etching method compared to DC method indicated by the reduction of full width at half maximum (FWHM). A broad visible photoluminescence (PL) was observed from green to red with blue shift as nanocrystallite size decreases which constituted quantum confinement effect from the PS structures. Nickel (Ni) finger contact was deposited onto the PS to form metal semiconductor metal (MSM) photodetector. Ni/PS MSM photodetector by pulse method exhibited higher gain (2 times) compared to conventional Si device at 5 V bias.
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Ashok, Anamika, Swathy B. Saseendran, and A. S. Asha. "Synthesis of Ti3C2Tx MXene from the Ti3AlC2 MAX phase with enhanced optical and morphological properties by using ammonia solution with the in-situ HF forming method." Physica Scripta 97, no. 2 (2022): 025807. http://dx.doi.org/10.1088/1402-4896/ac4c53.
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Abstract Liquid phase exfoliation of Ti3C2Tx MXene using LiF/HCl mix, forming HF in situ, has been modified by the addition of NH4OH. The base assisted dilution and extraction of MXene enables a quick control over pH and improves the structural, morphological and optical properties of the compound. The formation of a buffer compound NH4F, reduces the oxidation on the surface of MXene and etches off the residual MAX phase, by attacking Al. The structural features of the prepared NH4OH added Ti3C2Tx MXene are remarkably better than the HF etched samples, with the characteristic MXene peak in XRD being emphasized in the former. The addition of ammonia solution improves the milder in situ HF etching technique, by giving the characteristic open accordion structure to the compound, making the compound easy to delaminate and more stable against oxidation in ambient atmosphere.
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Liu, Wei Long, Yu Lun Hsieh, Shu Huei Hsieh, and Wen Jauh Chen. "Effects of Pd and Ni Metals Electrolessly Deposited on Si Nanowires on Properties of Photoelectrochemical Solar Cell." Advanced Materials Research 415-417 (December 2011): 686–89. http://dx.doi.org/10.4028/www.scientific.net/amr.415-417.686.
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A photoelectrochemical solar cell with a structure of modified Si nanowire anocle/K4Fe(CN)6+ K3Fe(CN)6/Pt cathode was prepared and studied. The Si nanowires were first formed by immersing n-Si chip in an etching solution of HF + AgNO3 and Pd and Ni metals were electrolessly deposited on the surface of Si nanowires. The modified anode was characterized by a scanning electron microscope for the surface and cross section view, and by an X-ray diffractometer for the phase and structure. The properties of the photoelectrochemical solar cell were measured under standard AM 1.5 simulated sunlight (100mW/cm2). The results showed that the total photoelectron conversion efficiency of the photoelectrochemical solar cell can be slightly increased when the Si nanowire anode was deposited with Pd metal, and can be greatly increased when deposited with Ni metal.
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Pei, Zingway, Jui-Po Sun, Hsin-Chen Lai, et al. "Formation of Through-Glass-Via (TGV) by Photo-Chemical Etching with High Selectivity." International Symposium on Microelectronics 2012, no. 1 (2012): 000785–92. http://dx.doi.org/10.4071/isom-2012-wp15.
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In this work, we utilize a photo-chemical etching (PCE) method to form through-glass-via (TGV). The PCE is a low cost, damage-free and potentially large-area method for TGV formation. An ultra-violet (355 nm) pulse laser was used to illuminate the glass surface. The illuminated region will crystallize after thermal annealing in a furnace. The crystallized glass shows much faster etching rate than the amorphous region in HF solution. For a relatively thick (600 nm) glass, a via-hole with diameter of around 60 μm was demonstrated in laser energy of 11 J/cm2. No laser damages were observed. In comparison, at least 10 times higher energy was required to drill a glass directly. Micro-cracks were form around the glass-via. In addition, a 40 selectivity was achieved to the crystallized and amorphous region. This simple and useful method paves a straight road for 3-D integration.
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Nayef, Uday Muhsin. "Sensitivity of gold nanoparticles doped in porous silicon." Iraqi Journal of Physics (IJP) 15, no. 35 (2018): 1–7. http://dx.doi.org/10.30723/ijp.v15i35.46.
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In this work gold nanoparticles (AuNPs), were prepared. Chemical method (Seed-Growth) was used to prepare it, then doping AuNPs with porous silicon (PS), used silicon wafer p-type to produce (PS) the processes doping achieved by electrochemical etching, the solution etching consist of HF, ethanol and AuNPs suspension, the result UV-visible absorption for AuNPs suspension showed the single peak located at ~(530 – 521) nm that related to SPR, the single peak is confirmed that the NPs present in the suspension is spherical shape and non-aggregated. X-ray diffraction analysis indicated growth AuNPs with PS. compare the PS layer without AuNPs and with AuNPs doped for electrical properties and sensitivity properties we found AuNPs:PS is more better than PS layer alone that refer to the AuNPs is improve properties PS.
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St John, Christopher, Christian L. Arrington, Jonathan Coleman, Mason Risley, and David Bruce Burckel. "Metasurface Optic Features Using Metal-Assisted Chemical Etching (MACE)." ECS Meeting Abstracts MA2024-02, no. 16 (2024): 1652. https://doi.org/10.1149/ma2024-02161652mtgabs.
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Metal-assisted chemical etching (MACE or MacEtch) is a versatile method for fabricating nano and micro-structured silicon (Si), which has garnered significant attention due to its potential applications in photovoltaics, sensors, and nanoelectronics. The process involves the oxidation of Si in the presence of a metal catalyst (typically noble metals like Au, Ag, or Pt) and a wet etch solution, usually comprising hydrofluoric acid (HF) and an oxidizing agent such as hydrogen peroxide (H2O2). Impressive work has already been completed in the two decades following the introduction of this method through the field of stain etching [1]. Researchers have reported anisotropic structures in silicon as high as 10,000:1 aspect ratio [2] and studied the impact of catalyst thickness [3], geometry [4], chemical ratios [5][6], and level of doping [7]. In this work, we systematically tune the selectivity of the MACE process based on the geometry of desired structures, chemical ratios of HF, H2O2 and ethanol, silicon doping types, and characteristics of the metal catalyst targeting our desired metasurface optic features. We use statistical analysis such as ensemble machine learning algorithms to create an informed understanding and importance matrix for each of these variables, toward the purpose of creating refractive optical features in silicon. The important parameters in the desired final product are vertical sidewalls, 10:1 aspect ratio, minimized surface roughness in the field, an optimized geometry, and a target depth. This comprehensive statistical analysis contributes to a deeper understanding of the MACE process, offering valuable guidelines for optimizing etching conditions to achieve desired micron to nanometer structures in silicon. The findings hold promise for advancing the fabrication of silicon-based nano-devices, paving the way for novel applications in various technological fields. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525 SAND2024-04791A [1] X. Li and P. W. Bohn, "Metal-assisted chemical etching in HF/H2O2 produces porous silicon," Applied Physics Letters, vol. 77, no. 16, pp. 2572-2574, 2000, doi: 10.1063/1.1319191. [2] L. Romano et al., "Metal assisted chemical etching of silicon in the gas phase: a nanofabrication platform for X-ray optics," Nanoscale Horizons, 10.1039/C9NH00709A vol. 5, no. 5, pp. 869-879, 2020, doi: 10.1039/C9NH00709A. [3] Z. Huang et al., "Extended Arrays of Vertically Aligned Sub-10 nm Diameter [100] Si Nanowires by Metal-Assisted Chemical Etching," Nano Letters, vol. 8, no. 9, pp. 3046-3051, 2008/09/10 2008, doi: 10.1021/nl802324y. [4] P. Lianto, S.-Y. Yu, J. Wu, C. V. Thompson, and W. K. Choi, "Vertical etching with isolated catalysts in metal-assisted chemical etching of silicon," Nanoscale, vol. 4 23, pp. 7532-9, 2012. [Online]. Available: https://doi.org/10.1039/C2NR32350H. [5] C. Chartier, S. Bastide, and C. Lévy-Clément, "Metal-assisted chemical etching of silicon in HF–H2O2," Electrochimica Acta, vol. 53, no. 17, pp. 5509-5516, 2008/07/01/ 2008, doi: https://doi.org/10.1016/j.electacta.2008.03.009. [6] W. Chern et al., "Nonlithographic Patterning and Metal-Assisted Chemical Etching for Manufacturing of Tunable Light-Emitting Silicon Nanowire Arrays," Nano Letters, vol. 10, no. 5, pp. 1582-1588, 2010/05/12 2010, doi: 10.1021/nl903841a. [7] R. A. Lai, T. M. Hymel, V. K. Narasimhan, and Y. Cui, "Schottky Barrier Catalysis Mechanism in Metal-Assisted Chemical Etching of Silicon," ACS Applied Materials & Interfaces, vol. 8, no. 14, pp. 8875-8879, 2016/04/13 2016, doi: 10.1021/acsami.6b01020. Figure 1
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Park, Jeong Woo, Noritaka Kawasegi, Noboru Morita, and Deug Woo Lee. "Mechanical Approach to Nanomachining of Silicon Using Oxide Characteristics Based on Tribo Nanolithography (TNL) in KOH Solution." Journal of Manufacturing Science and Engineering 126, no. 4 (2004): 801–6. http://dx.doi.org/10.1115/1.1811114.
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The TNL (Tribo Nanolithography) method in aqueous solution uses the atomic force microscopy as a machining tool for the nanoscale fabrication of silicon. A specially designed cantilever with a diamond tip allows the formation of oxide patterns easily by a simple scratching process. A rectangular structure with a slope can be fabricated by a process in which a thin oxide layer rapidly forms in the substrate at the diamond-tip sample junction along the scanning path of the tip, and, simultaneously, the area uncovered with the oxide layer is being etched. Etching in KOH and HF is conducted to verify corrosion characteristics of oxide.
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Zhao, Ming Fu, De Yi Huang, Bin Zhou, and Lei Zi Jiao. "Chemical Sensors Based on Fiber Bragg Grating." Applied Mechanics and Materials 84-85 (August 2011): 582–85. http://dx.doi.org/10.4028/www.scientific.net/amm.84-85.582.
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In this paper, measurement method for the refractive index of chemical substances based on fiber Bragg grating (FBG) sensor was proposed. The relation between Bragg wavelength shift and surrounding refractive index (SRI) was analyzed theoretically and experimentally. The SRI sensitivity of the chemical sensor could be enhanced by reducing the cladding thickness of the FBG using hydrofluoric acid (HF) solution etching process. The experimental results indicated that the variation of Bragg wavelength increased as the SRI increased. In the low SRI region, the relationship between the Bragg wavelength shift and the change of the SRI was approximately linear.