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Dissertations / Theses on the topic 'Semiconductors : Etching : Plasma etching'

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Published: 4 June 2021

Last updated: 6 February 2022

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1

Parks, Joseph Worthy Jr. "Microscopic numerical analysis of semiconductor devices with application to avalnache photodiodes." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/13539.

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2

Baker, Michael Douglas. "In-situ monitoring of reactive ion etching." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/15352.

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3

Toogood, Matthew John. "Studies of the chemistry of plasmas used for semiconductor etching." Thesis, University of Oxford, 1991. http://ora.ox.ac.uk/objects/uuid:e234bbaa-d6e6-4ac8-a3dd-aa9a2c1b1e39.

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Optical diagnostic techniques have been developed and then used to investigate the chemistry of reactive species formed in CF<sub>4</sub> / O<sub>2</sub> rf parallel plate discharges, similar to those employed in semiconductor material processing. Oxygen atoms were detected by two photon laser induced fluorescence (LIF), and the technique was found to have a number of experimental caveats owing mainly to the high laser intensities required. In particular, amplified spontaneous emission (ASE), was observed from laser excitation of oxygen, and was found to influence the spontaneous fluorescence signal and thus question the use of LIF for ground state concentration measurements in these systems. The spin orbit states of the 3p <sup>3</sup>P level were resolved for the first time, both in using high resolution excitation experiments and also as a consequence of detecting ASE. Spin orbit temperatures of less than 50° above ambient were observed. The absolute concentration of oxygen has been found to be 7.4 ± 1.4 x 10<sup>13</sup> cm<sup>-3</sup> in a 50 mTorr, 100 W, 85% O<sub>2</sub> / CF<sub>4</sub> plasma. Optical emission was also used to study fluorine atoms and to examine the use of the actinometered emission technique as a measure of ground state concentrations. The latter was investigated directly by comparison with LIF measurements of O and CF<sub>2</sub>, and in many cases shown to be a poor representation of the ground state concentration. To investigate the chemical and physical processes in the plasma, time resolved methods are required and a new technique, time resolved actinometry, has been developed, tested by comparison with LIF measurements and then used to study the kinetics of fluorine atoms. Results have shown the importance of wall reaction rates on the magnitude of the fluorine atom concentrations, and the sensitivity of these concentrations to the nature of the surface, particularly in the presence of oxygen and silicon. Oxygen has also been shown to be removed predominantly at the surface but the influence of gas phase reactions with CF<sub>x</sub> radicals is apparent in discharges containing low percentages of O<sub>2</sub>. Studies on an afterglow type, electron cyclotron resonance reactor have been carried out as a comparison to the parallel plate system, and high excitation and dissociation levels have been observed from differences in the emission intensities and from measured values of the absolute CF and CF<sub>2</sub> concentrations. The use of LIF as a diagnostic for CF has been investigated by probing the predissociation of the A<sup>2</sup>Σ<sup>+</sup> state. Emission from the A<sup>2</sup>Σ<sup>+</sup> (v = 2) level has been seen for the first time, and a J independent predissociation mechanism, with a rate of 3 x 10<sup>9</sup> s<sup>-1</sup> has been observed.

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4

Smith, Scott Alan. "INDUCTIVELY COUPLED PLASMA ETCHING OF III-N SEMICONDUCTORS." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-05082002-162142/.

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The principal focus of this research was the employment of an in-house designed and constructed inductively coupled plasma (ICP) system for integrated studies pertaining to the etching rates and etching selectivity among AlN, GaN, and Al(x)Ga(1-x)N. An (ICP) system was chosen because of its high plasma density and low cost relative to other high-density plasma etching systems. The etch rates were studied as a function of ICP power, pressure, DC bias, and gas composition. The use of a mixture of 2 sccm BCl3 and 18 sccm Cl2 resulted in a maximum etch rate of 2.2 microns/min for GaN as well as nearly vertical sidewalls with proper masking. A selectivity value, i.e. the ratio of the etch rates between two materials, as high as 48 was achieved between GaN and AlN with the addition of low concentrations of O2 to a Cl2/Ar chemistry. The use of another selectivity technique, namely, low DC biases resulted in a maximum selectivity of 38. The mechanisms responsible for the GaN etching were determined by monitoring both the ion density with a Langmuir probe and the relative Cl radical density with an optical emission spectrometer. Increasing the ion density resulted in a non-linear increase in the etch rates; increasing the Cl radical density had a minim al affect on etch rate.

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5

Steiner, Pinckney Alston IV. "Anisotropic low-energy electron-enhanced etching of semiconductors in DC plasma." Thesis, Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/27060.

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6

Krautschik, Christof Gabriel 1957. "Impedance determination of a RF plasma discharge by external measurements." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/277141.

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The equivalent impedance of a RF plasma was experimentally determined by monitoring the voltage and current waveform for different input powers in real time. Average ion energies and fluxes were determined by a computer model which takes ion collisions in the sheath regions into account. In addition two models were proposed which explain how RF energy is converted to DC potential energy in the sheath. Etch rates of Si in a CF₄ discharge were also evaluated and related to the measurements.

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7

Vas̆eková, Eva. "Spectroscopic studies of etching gases and microwave diagnostics of plasmas related to the semiconductor industry." n.p, 2006. http://physics.open.ac.uk/~ev295/!MASTER_THESIS.pdf.

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8

Fagan, James G. "Reactive ion etching of polymide films using a radio frequency discharge /." Online version of thesis, 1987. http://hdl.handle.net/1850/10284.

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9

Zhu, Hongbin. "Control of Plasma Etching of Semiconductor Surfaces." Diss., Tucson, Arizona : University of Arizona, 2005. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu%5Fetd%5F1354%5F1%5Fm.pdf&type=application/pdf.

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10

Carter, A. J. "The plasma etching of III-V semiconductor materials." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305164.

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11

Sucksmith, John Peter. "Studies of plasmas used for semiconductor etching." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335818.

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12

Beckman, Judith. "Low damage etching and deposition of electronic materials with a novel radio frequency plasma source." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362338.

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13

Rizquez, Moreno Maria Mercedes. "Characterization and optimization of high density plasma etching processes for advanced memories application." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM024.

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Parmi d’autres caractéristiques, la mémoire électronique idéale doit présenter une faible consommation d'énergie, haute densité et de la rapidité en lecture/écriture/effacement. Différents types de mémoires ont été ainsi développées. Un exemple en l’eSTM (Embedded Select Trench Memory). Ce travail de thèse étudie la caractérisation et l'optimisation des procédés de gravure plasma utilisés dans la fabrication de cette nouvelle technologie développée par STMicroelectronics Rousset, l'eSTM. Ce travail a été fortement lié à la caractérisation des parois du réacteur, le plasma lui-même et la surface de la plaquette de silicium. La caractérisation chimique des surfaces exposées aux plasmas a permis de caractériser et d'optimiser ce nouveau procédé de gravure. De plus, cette étude vise également à comprendre les dépôts sur les parois du réacteur qui se produisent pendant la gravure de la tranchée de l’eSTM. Ces interactions sont responsables de l’absence de reproductibilité des procédés de gravure. La gravure plasma est contrôlée par la formation d'une couche de passivation se formant en surface des flancs du silicium. La maitrise de cette couche par les conditions du plasma (pression, puissance source débit de gaz...) a permis de développer un model innovant afin d'optimiser le CD de la tranchée. De plus, cette thèse a également porté sur l'étude des dérives des CD au niveau des STI (Shallow Trench Isolation). Des mesures correctives ont été développées afin de contrôler les sources de variations en créant une nouvelle stratégie de gravure pour corriger la dispersion des CD entre lots (25 plaquettes de silicium)<br>Among other characteristics, the ideal memory should have low power consumption, fast read/write/erase and high density solution. Different types of memories have been developed to pursuit these specific properties. Example of this attempt is the eSTM (Embedded Select Trench Memory). This PhD work studies the characterization and optimization of the plasma etching processes for this new technology developed by STMicroelectronics, the eSTM. This work has been highly related to the characterization of the reactor walls, the plasma itself and the wafer surface. The main objectives of this thesis are to understand the fundamental mechanisms of the etching processes and to propose innovative solutions to reduce the variations of CD by reaching the good control of the process desired. This thesis would help for the enhancement of our knowledge on the physical phenomena which happens during this process, especially the passivation. This would offer the possibility of optimize the etch process and get the best CD (Critical Dimension) in terms of electrical results. The emphasis, was put on the characterization to get the maximum knowledge about the interactions taking place during the process, such as plasma-surface interactions and plasma-reactor wall interactions. Furthermore, this thesis was also focused on the optimization of the process drifts at STI (Shallow Trench Isolation) level, since the reproducibility of production processes generates serious concerns in making the component of the chips. Therefore, corrective actions were developed to control the source of variations by creating a regulation loop able to correct the CD dispersion between lots (25wafers)

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14

Bose, Abhijit Frank. "Diagnostics and control of plasma etching reactors for semiconductor manufacturing /." [S.l.] : [s.n.], 1995. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=11224.

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15

Boysen, Christopher J. "An analysis and development of controls for exposures to maintenance personnel working on the plasma metal etchers." Online version, 1998. http://www.uwstout.edu/lib/thesis/1998/1998boysenc.pdf.

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16

Morris, Bryan George Oneal. "In situ monitoring of reactive ion etching." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31688.

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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.<br>Committee Chair: May, Gary; Committee Member: Brand,Oliver; Committee Member: Hasler,Paul; Committee Member: Kohl,Paul; Committee Member: Shamma,Jeff. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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17

Dartnell, Nicholas John. "Dry etching of silicon based semiconductor materials : plasma diagnostics and reaction mechanics." Thesis, University of Southampton, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239655.

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18

Murad, Saad Kheder. "Characterization of dry etching processes of III-V semiconductors in silicon tetrachloride plasmas." Thesis, University of Glasgow, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297037.

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19

Thomas, David John. "Mass spectroscopy of the etching of Si and SiOâ†2 in CFâ†4/Oâ†2 plasmas and X-ray photoelectron spectroscopy of plasma deposited borophosphosilicate glasses." Thesis, University of Bristol, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294220.

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20

Chen, Xiaoming. "Laser-cluster interaction and its applications in semiconductor processing /." Digital version accessible at:, 1999. http://wwwlib.umi.com/cr/utexas/main.

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21

Yue, Hongyu. "Multivariate statistical monitoring and diagnosis with applications in semiconductor processes /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.

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22

Myneni, Satyanarayana. "Post Plasma Etch Residue Removal Using Carbon Dioxide Based Fluids." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7605.

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As feature sizes in semiconductor devices become smaller and newer materials are incorporated, current methods for photoresist and post plasma etch residue removal face several challenges. A cleaning process should be environmentally benign, compatible with dielectric materials and copper, and provide residue removal from narrow and high aspect ratio features. In this work, sub-critical CO2 based mixtures have been developed to remove the etch residues; these mixtures satisfy the above requirements and can potentially replace the two step residue removal process currently used in the integrated circuit (IC) industry. Based on the chemical nature of the residue being removed, additives or co-solvents to CO2 have been identified that can remove the residues without damaging the dielectric layers. Using the phase behavior of these additives as a guide, the composition of the co-solvent was altered to achieve a single liquid phase at moderate pressures without compromising cleaning ability. The extent of residue removal has been analyzed primarily by x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Various techniques such as attenuated total reflection - Fourier transform infrared (ATR-FTIR) spectroscopy, angle-resolved XPS (ARXPS), and interferometry were used to probe the interaction of cleaning fluids with residues. Model films of photoresists and plasma deposited residues were used to assist in understanding the mechanism of residue removal. From these studies, it was concluded that residue removal takes place primarily by attack of the interface between the residue and the substrate; a solvent rinse then lifts these residues from the wafer. It has been shown that transport of the additives to the interface is enhanced in the presence of CO2. From positronium annihilation lifetime spectroscopy (PALS) studies on a porous dielectric film, it has been shown that these high pressure fluids do not cause significant changes to the pore sizes or the bonding structure of the film. Hence, this method can be used to remove post etch residues from low-k dielectric films.

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23

Martin, Patrick. "Étude du transport et de la formation de particules pendant l'étape microélectronique de gravure assistée plasma." Université Joseph Fourier (Grenoble ; 1971-2015), 1994. http://www.theses.fr/1994GRE10233.

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Dans l'industrie de la microelectronique, la contamination particulaire est responsable d'une reduction importante des performances des procedes de fabrication. Les procedes assistes plasma, et notamment les procedes de gravure seche sont une source particulierement nefaste de contamination particulaire. Nos travaux nous ont conduit, tout d'abord, a mettre au point et a evaluer des moyens in-situ (diffusion de la lumiere, mesure electriques) pour caracteriser la dimension et la densite des particules. Grace a ces dispositifs, nous avons etudie le transport des particules lors de l'etape critique pour la contamination des substrats en cours de traitement que constitue l'extinction du plasma. Nous avons ensuite analyse la formation des particules dans des plasmas d'argon (pulverisation) et des plasmas de trifluoromethane (gravure ionique reactive). La derniere partie de nos travaux est consacree a l'analyse de l'efficacite des procedes de nettoyage des reacteurs par des plasmas pulses

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24

Lloyd, Neil Stuart. "Interactions between molecules and surfaces : part 1- plasma etching of Si, Ge and Siâ†1â†-â†xGeâ†x alloys; part 2 - adsorption and desorption of methyl salicylate on various wall coverings." Thesis, University of Southampton, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241949.

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25

Phan, Thanh Long. "Etude fondamentale des mécanismes physico-chimiques de gravure plasma basés sur les effets stériques et de diffusion. Comportements prévisionnels de la gravure des éléments de la colonne IV et des composés III-V par les halogènes : loi de similitude." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-01062182.

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L'objectif de ce travail porte sur la généralisation de la modélisation de la gravure du silicium dans les plasmas de fluor ou de chlore à celle de la gravure des éléments de la colonne IV et des composés III-V de structure cristalline de type diamant ou zinc-blende dans les plasmas d'halogènes, i.e. fluor, chlore, brome et iode. Dans ce contexte, les effets stériques et de diffusion en volume et/ou en surface en constituent les problématiques principales. Cette généralisation s'appuie sur le modèle de gravure de Petit et Pelletier qui, par rapport aux modèles antérieurs, prend en compte un certain nombre d'hypothèses distinctes ou additionnelles telles que les interactions répulsives entre adatomes d'halogènes proches voisins, les mécanismes de Langmuir-Hinshelwood pour la formation des produits de réaction, la nature mono-couche ou multi-couches de l'adsorption, et la diffusion des adatomes en surface. Les effets stériques relatifs à la diffusion des atomes d'halogènes à travers les surfaces (100) des structures cristallines des éléments de la colonne IV et des composés III-V définissent une première loi de similitude entre la maille du réseau cristallin et le rayon ionique de Shannon des atomes d'halogènes concernant leurs conditions de diffusion en volume. Cette loi se traduit par un diagramme prévisionnel, commun aux éléments de la colonne IV et aux composés III-V, délimitant les systèmes de gravure de types mono-couche et multi-couches. Les effets stériques relatifs aux mécanismes réactionnels de gravure sur les surfaces (100) aboutissent à des secondes lois de similitude entre la maille du réseau et le rayon covalent des adatomes d'halogènes caractérisant la nature de la gravure : gravure isotrope, gravure anisotrope, ou absence de gravure. Ces lois de similitude, distinctes pour les éléments de la colonne IV et les composés III-V (stœchiométrie différente des produits de réaction), se traduisent par deux diagrammes prévisionnels délimitant les différents domaines de gravure. Les diagrammes prévisionnels pour les éléments de la colonne IV ont pu être validés, d'une part, à partir des résultats expérimentaux antérieurs, et, d'autre part, en l'absence de données, à partir d'études expérimentales complémentaires : gravure de Si et Ge en plasma de brome et d'iode, gravure de Sn en plasma d'iode.

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26

Girgel, Ionut. "Development of InGaN/GaN core-shell light emitters." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.720648.

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Gallium nitride (GaN) and its related semiconductor alloys are attracting tremendous interest for their wide range of applications in blue and green LEDs, diode lasers, high-temperature and high-power electronics. Nanomaterials such as InGaN/GaN core-shell three-dimensional nanostructures are seen as a breakthrough technology for future solid-state lighting and nano-electronics devices. In a core-shell LED, the active semiconductor layers grown around a GaN core enable control over a wide range of wavelengths and applications. In this thesis the capability for the heteroepitaxial growth of a proof-of-principle core-shell LED is advanced. A design that can be applied at the wafer scale using metalorganic vapor phase epitaxy (MOVPE) crystal growth on highly uniform GaN nanorod (NR) structures is proposed. This project demonstrates understanding over the growth constraints of active layers and dopant layers. The impact of reactor pressure and temperature on the morphology and on the incorporated InN mole fraction was studied for thick InGaN shells on the different GaN crystal facets. Mg doping and effectiveness of the p-n junction for a core-shell structure was studied by extensive growth experiments and characterization. Sapphire and Si substrates were used, and at all the stages of growth and fabrication. The structures were optimized to achieve geometry homogeneity, high-aspect-ratio, incorporation homogeneity for InN and Mg dopant. The three-dimensional nature of NRs and their light emission provided ample challenges which required adaptation of characterization and fabrication techniques for a core-shell device. Finally, an electrically contacted core-shell LED is demonstrated and characterized. Achieving a proof-of-principle core-shell device could be the starting point in the development of nanostructure-based devices and new physics, or in solving technical problems in planar LEDs, such as the polarization of emitted light, the quantum-confined Stark effect, efficiency droop, or the green gap.

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27

Chen, Hsin-Yi. "Inductively coupled plasma etching of InP." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0021/MQ54126.pdf.

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28

Khon, Elena. "Synthesis and Applications of Heterostructured Semiconductor Nanocrystals." Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1374512926.

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29

Ganguli, Satyajit Nimu. "A kinetic study of chromium etching /." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63943.

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30

Rieger, Melissa Marie. "The electrochemical etching of silicon in nonaqueous solutions." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/10214.

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31

Jamali, Arash. "Etching of wood by glow-discharge plasma." Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/39882.

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In this thesis I hypothesize that plasma will etch wood surfaces, produce new cell wall microstructures, and change the surface chemistry of wood because of differential etching of wood’s polymeric constituents. I also examine factors affecting the etching of wood by plasma, and applications of plasma etching for wood processing. Scanning electron and light microscopy and white light confocal profilometry were used to examine etching of wood surfaces. Wet chemical analysis, FTIR and XPS spectroscopy were used to analyze chemical changes at the surface of plasma-treated wood. Experiments were also performed to examine the effect of plasma treatments on the color of blue-stained wood, the morphology of fungal hyphae and the adhesion and performance of coatings on hot-oil modified wood. Exposure of wood to plasma caused etching of wood cell walls and created new surface microstructures. Regions of cell walls that were rich in lignin such as the middle lamella were etched more slowly by plasma. Confocal profilometry of wood exposed to plasma revealed a strong relationship between plasma treatment time and etching of cell walls, and same technique found that lignin pellets were etched more slowly than cellulose pellets. Plasma reduced the levels of carbohydrate at the surface of modified wood, which resulted in a relative increase in lignin content. Plasma treatment improved the effectiveness of hypochlorite bleach at removing blue-stain from wood and it prevented the discoloration of a white acrylic paint on hot-oil modified wood exposed to natural weathering. However, plasma treatment of hot-oil modified wood did not have positive effects on the adhesion and exterior performance of a range of other coatings (mainly semi-transparent stains). I conclude that prolonged exposure to plasma can etch wood cell walls, but cell wall layers that are rich in lignin are degraded more slowly. Plasma etching of wood mainly depends on treatment time and also on the structure and chemical composition of wood. Plasma treatment is an efficient pre-treatment for bleaching of blue-stained wood and reducing the discoloration of white acrylic paint on hot-oil modified wood.

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32

Goodlin, Brian E. 1974. "Multivariate endpoint detection of plasma etching processes." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8498.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2002.<br>Includes bibliographical references.<br>In plasma etching process it is critical to know when the film being etched has cleared to the underlying film, i.e. to detect endpoint, in order to achieve the desired device performance in the resulting integrated circuit. The most highly utilized sensor technology for determining endpoint has historically been optical emission spectroscopy (OES), because it is both non-invasive and highly sensitive to chemical changes in the reactor. Historically, the intensity of one emission peak corresponding to a reactant or product in the etch process was tracked over time, leading to a single-wavelength endpoint trace. At endpoint, the concentrations of reactant and product species undergo a step change that is detectable in the optical emission endpoint trace for many plasma etching processes. Unfortunately, for several critical etching steps (contact and via), the exposed area of the film being etched is very low (<1%, with the rest being masked with photoresist),. and this traditional method of endpoint detection has failed because of the low signal-to-noise ratio at endpoint. Our work has provided a way to improve the endpoint detection sensitivity by a factor of approximately 5-6, so that endpoint can be adequately detected for these low open area etching steps. By utilizing CCD array detection for OES sensors, it is possible to rapidly collect (2-10 Hz) full spectral data (200-900 nm in wavelength), consisting of over 1000 discrete wavelength channels from a plasma etching process. By appropriately utilizing this multi-wavelength data, we have been able to achieve significant improvements in sensitivity. Our work has focused on characterizing, analyzing, and developing new multivariate (multi-wavelength) strategies to optimize the sensitivity of the endpoint detector.<br>(cont.) This thesis provides a thorough comparison of several different multivariate techniques for improving endpoint detection sensitivity and robustness, both experimentally and theoretically. The techniques compared include: 1) multivariate statistical process control metrics such as Hotelling's T2; 2) chemometrics techniques such as principal component analysis (PCA) and T2 and Q statistics based on PCA, evolving window factor analysis (EWFA); 3) discriminant analysis; and 4) a new methodology called the Multi-wavelength statistic weighted by Signal-to-Noise ratio or MSN Statistic. A quantitative methodology based on signal-to-noise analysis was employed to compare the various techniques. Following this type of analysis, the MSN statistic was developed to theoretically provide the optimal improvement in endpoint detection sensitivity given certain assumptions about the nature of the noise in the data. Applying the MSN statistic to experimentally collected endpoint data confirmed that it did give superior results. By utilizing information about the direction (in the multivariate space) of endpoint from prior runs, the MSN statistic showed significant improvement over the traditional multivariate T2 statistic, that does not use any prior knowledge for detection. Another important aspect of the work was in characterizing the nature of multivariate noise, and understanding how different multivariate algorithms treat the different forms of multivariate noise. In general, we found that multivariate noise could be broadly classified into two components ...<br>by Brian E. Goodlin.<br>Ph.D.

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33

Canvel, Yann. "Etude du procédé de gravure de l'alliage Ge-Sb-Te pour les mémoires à changement de phase." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALY017.

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Les mémoires ont très largement gagné en notoriété ces dernières années et sont désormais incontournables dans tous les systèmes électroniques avec lesquels nous interagissons dans la vie quotidienne. Pour pallier les limitations technologiques des mémoires traditionnelles, de nombreux acteurs industriels ont orienté leur développement vers les Mémoires à Changement de Phase (PCM). Le fonctionnement de cette technologie émergente repose principalement sur les propriétés d’un alliage chalcogénure type Ge-Sb-Te (GST). Selon la composition chimique du matériau GST, les caractéristiques de la mémoire adressent différents marchés. Il est donc impératif que le matériau GST demeure intègre au cours des étapes d’élaboration de la cellule mémoire afin de satisfaire aux performances attendues. C’est un point critique à prendre en compte dans le procédé de fabrication du composant.L’objectif de cette thèse est de comprendre les interactions matériau – environnement susceptibles de menacer la stabilité chimique du GST et de proposer des solutions pour s’opposer aux effets les plus néfastes. Dans un premier temps, nous nous sommes intéressés à l’impact de la gravure plasma sur le matériau GST par l’étude comparative de trois chimies halogènes à base de HBr, Cl2 et CF4. Grâce aux résultats complémentaires des techniques XPS, PP-TOFMS et AFM, nous avons montré que la gravure HBr permet de minimiser les modifications chimiques et morphologiques de la surface du GST. Dans un second temps, nous avons cherché à comprendre comment le matériau GST réagissait aux différents procédés intervenant après l’étape de gravure. Il a été démontré que l’exposition du GST à un environnement oxydant (plasma O2 ou air) induit une oxydation critique détériorant les propriétés de changement de phase du matériau. De plus, le traitement chimique utilisé pour nettoyer les flancs de la structure PCM élimine sélectivement l’oxyde de GST et peut, en conséquence, altérer la morphologie des cellules mémoires. Pour éviter ces effets, nous avons proposé plusieurs solutions de procédé plasma capables de préserver la composition chimique du GST au cours du procédé d’élaboration de la structure PCM. En particulier, nous avons pu tirer profit des avantages que constitue l’ajout de CH4 dans le plasma. Il contribue à créer une couche de passivation lors de la gravure du GST ou est utilisé comme précurseur d’un dépôt de protection. Le développement d’une chimie de gravure alternative en H2-N2-Ar a également été abordé et représente une perspective intéressante<br>Memories have gained a lot of influence through these last years and are present in all electronic systems used in our daily life. To address the limitations of the traditional memory technologies, many industries are dedicating their researches to the development of the Phase-Change Memories (PCM). This emerging technology mainly uses the properties of a Ge-Sb-Te based-chalcogenide alloy (GST). The memory characteristics may change according to the GST chemical composition. This is a critical point to carefully consider for the manufacturing process of the component. Indeed, it is crucial to preserve as much as possible the GST integrity all along the patterning steps of the memory cell in order to preserve the device performances.This thesis work aims at understanding the material – environment interactions likely to impact the GST chemical stability and propose some improvements to the processes that are detrimental for the material. Firstly, we have focused on the plasma etching effects on the GST alloy through the comparative study of three halogen chemistries, HBr, Cl2 et CF4. Thanks to the complementary results from XPS, PP-TOFMS and AFM measurements, the HBr chemistry was identified as the best etching strategy for limiting damages at the GST surface. Secondly, we have investigated the GST interactions with the different environments implemented during the subsequent fabrication processes. The GST exposition to an oxidizing environment (O2 based-plasma or air) induces a critical oxidation damaging the phase-change properties. Besides, the chemical treatment used to clean the PCM sidewalls removes selectively the GST oxide and, consequently, can modify the memory cell morphology. To prevent these effects, several plasma solutions are suggested in order to maintain the chemical stability of the GST material during the PCM patterning process. In particular, knowing the benefits of a CH4 plasma, we propose to either integrate it into a passivating etching process or to use it as a precursor promoting a protection layer. The development of an alternative etching chemistry in H2-N2-Ar has also been discussed and opens an interesting perspective

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34

Hendricks, Douglas Ray 1958. "REACTIVE ION ETCHING OF GALLIUM-ARSENIDE AND ALUMINUM-GALLIUM - ARSENIDE USING BORON TRICHLORIDE AND CHLORINE." Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276394.

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35

Houghten, Jonathan Lester 1964. "Etching in silicon-dioxide with a controllable sidewall angle." Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276768.

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A selective sloped silicon dioxide etching method has been studied using a temperature controlled diode-type reactive ion etch system with CHCl₃, C₂F₆, H₂ and N₂ gases. The SiO₂ was covered by a polyimide mask with vertical sidewalls and window openings from 1.25-4 microns. Control of the sidewall slope in SiO₂ is possible through varying the ratios of CHCl₃ and C₂F₆. High percentages (95-100%) of CHCl₃ resulted in low etch rates of 420 angstroms/min. Large slopes of up to 65 degrees are possible. With C₂F₆ above 5%, larger etch rates close to 2000 angstroms/min. occur and etching becomes vertical with purely anisotropic profiles at 10% C₂F₆. In a simulation study, SiO₂ sidewall slope was found to be controlled by the isotropic deposition rate as well as the anisotropic etch rate. Optical Multichannel Analysis of the discharge showed an increase in silicon dioxide removal when the percentage of C₂F₆ was increased. (Abstract shortened with permission of author.)

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36

Samara, Vladimir. "Negative ions and neutral beams in plasma etching." Thesis, Open University, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.534386.

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37

Rizvi, Syed Shabbar Abbas. "Inductively coupled Ar/Clâ‚‚ plasma etching of GaN." Thesis, University of Ulster, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288895.

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38

Tao, Benjamin A. (Benjamin Albert). "Non-perfluorocompound chemistries for plasma etching of dielectrics." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40603.

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Dalton, Timothy Joseph. "Pattern dependencies in the plasma etching of polysilicon." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/11655.

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40

Astell-Burt, P. J. "Studies on etching and polymer deposition in halocarbon plasmas." Thesis, University of Oxford, 1987. http://ora.ox.ac.uk/objects/uuid:d8fd1069-a66b-4372-8ba0-b9ca5367445c.

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Plasma etching, the selective removal of materials by reaction with chemically active species formed in a glow-discharge, is widely used by the electronics industry because of the advantages over 'wet' processes. The full potential has yet to be realised because chemical processes occuring in the plasma and at the plasma/substrate interface are incompletely understood. In this work attention was focussed on the accumulation of polymers on surfaces during plasma etching in fluorocarbon gases. An apparatus was designed and constructed to explore the conditions which give rise to these deposits by: i) The detection of the excited species such as CF and CF<sub>2</sub> (by optical emission spectroscopy); and ii) The rate of accumulation or removal of deposits (by means of a quartz crystal microbalance). The gases CF<sub>4</sub>, C<sub>2</sub>F<sub>6</sub>, C<sub>3</sub>F<sub>8</sub> and CHF<sub>3</sub> were used at pressures between 200-600mT, together with mixtures with H<sub>2</sub> and a few runs with other gases to vary the partial pressures of etching and polymerizing species. Both substrate effect of, viz silicon and thermally oxidised silicon (SiO<sub>2</sub>), and electrode materials effects have been examined. Polymer production from C<sub>3</sub>F<sub>8</sub> has been found to be more sensitive to electrode composition than that from CHF<sub>3</sub>, but the material formed is overall less thermally stable. On the other hand, polymers produced from C<sub>3</sub>F<sub>8</sub> accumulate at similar rates on Si and SiO<sub>2</sub>, whereas those from CHF3 show a much greater liklihood of building up on Si than SiO2 . XPS and infra-red spectroscopy have been used to demonstrate that polymers arising from these two gases exhibit marked structural differences, which can be minimised by mixing H<sub>2</sub> with C<sub>3</sub>F<sub>8</sub>. These effects can be correlated with the decomposition products expected in the plasma.

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41

Hoshino, Isako. "Hyperthermal molecular beam dry etching of III-V compound semiconductors." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43365.

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42

Mancheno, Posso Pablo Leonardo. "Liquid-Phase Etching and Chemical Passivation of III-V Semiconductors." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/612461.

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The development of metal-oxide-semiconductor field effect transistor (MOSFET) technology relies on new channel materials with higher carrier mobilities that allow faster switching but at lower voltages. III-V semiconductors are suitable for channel materials in n-type MOSFETs due to their higher electron mobility. However, the interface between the gate dielectric and the III-V surface shows defects that detriment the electrical performance of the transistor. These defects are attributed to interfacial oxides that create energy states in the band gap. Therefore, III-V oxides must be removed and the surface must be protected from reoxidation for the deposition of other functional layers. In this work, oxide etching and passivation of III-V semiconductors were studied to understand the oxide etching mechanism and to develop passivation techniques that allow the integration of these materials in device manufacturing. The etching of GaAs(100) was studied using aqueous HCl and H₂O₂ mixtures with and without the addition of alpha-hydroxy acids. Oxide etching depends on the strength of the acid. Without the addition H₂O₂, acetic, glycolic, tartaric and hydrochloric acids (pKₐ lower than 5) are able to remove oxides. Upon the addition of H₂O₂, only the stronger acids (glycolic, tartaric and hydrochloric) with a pKₐ lower than 4 are able to compete with H₂O₂ and etch the oxides. Oxide removal leaves an As-rich surface, and in the case of HCl, etching leaves a surface terminated with As-Cl species. As-As dimers are formed when oxides are etched with HCl and organic acids. After oxide removal with HF or HCl, the fresh GaAs and InP surfaces were passivated with a series of alkanethiols (C(n)H(2n+1)SH) to assess their effectiveness in protecting the substrate from reoxidation. Longer C chains provided increased protectiong due to their increased chain-chain interactions that allow them to form a denser and well-ordered monolayer. The surface is chemically passivated through S-X (where X = As, Ga for GaAs, and In for InP) bonding between the alkanethiolate layer and the surface. A layer formed by 1-eicosanethiol protected GaAs for 30 min, but prevented reoxidation of InP for at least 5 hours. Since the thickness of the alkanethiol layer is the same, the difference in protection is a result of the density of the layer and S bonding with the substrate.

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43

Perng, John Kangchun. "High Aspect-Ratio Nanoscale Etching in Silicon using Electron Beam Lithography and Deep Reactive Ion Etching (DRIE) Technique." Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11543.

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This thesis reports the characterization and development of nanolithography using Electron Beam Lithography system and nanoscale plasma etching. The standard Bosch process and a modified three-pulse Bosch process were developed in STS ICP and Plasma ICP system separately. The limit of the Bosch process at the nanoscale regime was investigated and documented. Furthermore, the effect of different control parameters on the process were studied and summarized in this report. 28nm-wide trench with aspect-ratio of 25 (smallest trench), and 50nm-wide trench with aspect ratio of 37 (highest aspect-ratio) have been demonstrated using the modified three-pulse process. Capacitive resonators, SiBAR and IBAR devices have been fabricated using the process developed in this work. IBARs (15MHz) with ultra-high Q (210,000) have been reported.

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Jia, Ningning, and 贾宁宁. "Optimization schemes for process robustness enhancement in optical lithography." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B47028592.

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Vasekova, Eva. "Spectroscopic studies of etching gases and microwave diagnostics of plasmas related to the semiconductor industry." Thesis, Open University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.690909.

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46

Booth, J. P. "Laser studies of species involved in plasma etching processes." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233432.

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47

Kong, Yung 1967. "Particle contamination in sulfur-hexafluoride/argon plasma etching process." Thesis, The University of Arizona, 1991. http://hdl.handle.net/10150/277919.

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Process generated particle contamination on unpatterned silicon wafers etched in an SF6/argon plasma using a Tegal MCR-1 etcher in the plasma triode-1 mode was characterized using response surface methodology. Particle deposition was observed to be a predictable function of plasma parameter space, which can be determined by relatively few statistically designed experiments. A model of particle deposition as a function of 13.56 MHz chamber electrode rf power, chamber pressure, gas flow rate, etch time and 100 kHz wafer electrode power was constructed. It is found that particle deposition depends linearly on etch time and both 13.56 MHz and 100 kHz power. In addition, particle deposition increased with gas flow rate at low flow rate, reaches a maximum, then decreased as flow rate increased further. Moreover, there was no observable effect on particle deposition due to pressure variation in the pressure range explored. Auger chemical analysis showed that the particles contained elemental sulfur, fluorine, silicon, aluminum, carbon and oxygen. Most particles were typically less than 2 μm in diameter.

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Rodgers, Seth Thomas 1970. "Multiscale modeling of chemical vapor deposition and plasma etching." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/28219.

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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2000.<br>Includes bibliographical references.<br>In this work, a framework and a set of modeling tools capable of describing systems with key processes occurring on widely separated length and time scales has been developed. The major focus of this work is linking atomistic and continuum descriptions of gas phase transport. This problem is of considerable practical interest, as most etching and CVD processes are run at low pressures ~ 1 torr or less. Under these conditions, the continuum diffusion models used to describe flow and transport in a typical reactor will fail below scales of a few hundred microns, and thus are not useful in describing transport in and around microscale topography. This is a serious limitation, as such topography is present in most microelectronic devices. Two methods for linking discrete particle (or feature scale) and continuum models of precursor transport are presented. The discrete and continuum models are coupled by boundary conditions at their mutual interface (just above any reactive surface with microscale detail) The first approach employs an effective reactivity function e,, which is computed through a hybrid probabilistic-deterministic MC method e. can be interpreted as a representation of the average fate of molecules entering the feature scale domain from the macroscopic model. An example of tungsten CVD over a substrate with surface topography typical of modern microelectronic devices is presented. A second, deterministic technique was also developed as an improvement on the Monte Carlo approach. The deterministic method uses the matrix of transmission probabilities, or shape kernel, to summarize all microscale events in a fashion consistent with a continuum macroscopic model. The deterministic linking algorithm is over 1,000 times faster than the previously presented MC method. The speed advantage enables simulation of detailed chemistry. Plasma etching presents a very similar multiscale problem and a strategy for linked plasma etching simulations is presented. Finally, a study of ionized physical vapor deposition of aluminum is presented as an example of atomistic-continuum linking. Molecular dynamics simulations are used to represent atomistic events. The Molecular Dynamics results are summarized in a manner that allows the combination of atomistic information with a continuum (level -set) model for evolution of the deposited metal film.<br>by Seth Thomas Rodgers.<br>Ph.D.

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49

Steans, Pippa Helen. "Morphological changes during the growth and etching of 111-V semiconductors." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325364.

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50

Nicol, Irene. "Etching and chemomechanical polishing of compound semiconductors using halogen-based reagents." Thesis, University of Glasgow, 1996. http://theses.gla.ac.uk/1631/.

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The reactions of dichlorine and dibromine on compound semiconductors follow a pattern of halogenation of the substrate surface, followed by solvation of the halogenated products and removal of the secondary products in the etchant solutions. The reactions of hypochlorite and hydrogen peroxide follow a similar pattern, beginning with oxidation of the substrate surface, followed by subsequent hydration in the etchant solution and final product removal. The solubility of the products and the action of the polishing pad and abrasive are all critical to the passivation of the surface and the production of a polished substrate. The pH dependence of sodium hypochlorite is explained in terms of its composition. At low pH (<8) the main component of the etchant solution is dichlorine. At high pH (>8) the main component of the etchant solution is hypochlorite anion. Thus hypochlorite solution may be considered as a parallel to dibromine at low pH, but is more consistent with the behaviour of hydrogen peroxide at high pH. Thus, aqueous sodium hypochlorite solution may be formulated as part of the series O-O, O-X, X-X, where X represents a halogen. The General Model for Chemomechanical Polishing is formulated on the basis of the three stages of reaction observed for all the reagents examined: Oxidation of the substrate; solvation/hydration of the oxidation products; removal of the products from the substrate surface. Novel bromine-based organic reagents have been designed, synthesised and used to etch and polish gallium arsenide and cadmium telluride substrates. These compounds have shown that properties such as stock removal rate, pH dependence and selectivity may be predicted and even designed into etchants to produce the optimum conditions for polishing a given substrate.

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