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1
Pinto, Raquel, André Cardoso, Sara Ribeiro, Carlos Brandão, João Gaspar, Rizwan Gill, Helder Fonseca, and Margaret Costa. "Application of SU-8 photoresist as a multi-functional structural dielectric layer in FOWLP." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2017, DPC (January 1, 2017): 1–19. http://dx.doi.org/10.4071/2017dpc-tp2_presentation3.
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Microelectromechanical Systems (MEMS) are a fast growing technology for sensor and actuator miniaturization finding more and more commercial opportunities by having an important role in the field of Internet of Things (IoT). On the same note, Fan-out Wafer Level Packaging (FOWLP), namely WLFO technology of NANIUM, which is based on Infineon/ Intel eWLB technology, is also finding further applications, not only due to its high performance, low cost, high flexibility, but also due to its versatility to allow the integration of different types of components in the same small form-factor package. Despite its great potential it is still off limits to the more sensitive components as micro-mechanical devices and some type of sensors, which are vulnerable to temperature and pressure. In the interest of increasing FOWLP versatility and enabling the integration of MEMS, new methods of assembling and processing are continuously searched for. Dielectrics currently used for redistribution layer construction need to be cured at temperatures above 200°C, making it one of the major boundary for low temperature processing. In addition, in order to accomplish a wide range of dielectric thicknesses in the same package it is often necessary to stack very different types of dielectrics with impact on bill of materials complexity and cost. In this work, done in cooperation with the International Iberian Nanotechnology Laboratory (INL), we describe the implementation of commercially available SU-8 photoresist as a structural material in FOWLP, allowing lower processing temperature and reduced internal package stress, thus enabling the integration of components such as MEMS/MOEMS, magneto-resistive devices and micro-batteries. While SU-8 photoresist was first designed for the microelectronics industry, it is currently highly used in the fabrication of microfluidics as well as microelectromechanical systems (MEMS) and BIO-MEMS due to its high biocompatibility and wide range of available thicknesses in the same product family. Its good thermal and chemical resistance and also mechanical and rheological properties, make it suitable to be used as a structural material, and moreover it cures at 150°C, which is key for the applications targeted. Unprecedentedly, SU-8 photoresist is tested in this work as a structural dielectric for the redistribution layers on 300mm fan-out wafers. Main concerns during the evaluation of the new WLFO dielectric focused on processability quality; adhesion to multi-material substrate and metals (copper, aluminium, gold, ¦); between layers of very different thicknesses; and overall reliability. During preliminary runs, processability on 300 mm fan-out wafers was evaluated by testing different coating and soft bake conditions, exposure settings, post-exposure parameters, up to developing setup. The outputs are not only on process conditions and results but also on WLFO design rules. For the first time, a set of conditions has been defined that allows processing SU-8 on WLFO, with thickness values ranging from 1 um to 150 um. The introduction of SU-8 in WLFO is a breakthrough in this fast-growing advanced packaging technology platform as it opens vast opportunities for sensor integration in WLP technology.
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Butler, Jeffrey T., Victor M. Bright, and John H. Comtois. "Multichip module packaging of microelectromechanical systems." Sensors and Actuators A: Physical 70, no. 1-2 (October 1998): 15–22. http://dx.doi.org/10.1016/s0924-4247(98)00107-1.
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Lee, Y. C., B. A. Parviz, J. A. Chiou, and S. Chen. "Packaging for microelectromechanical and nanoelectromechanical systems." IEEE Transactions on Advanced Packaging 26, no. 3 (August 2003): 217–26. http://dx.doi.org/10.1109/tadvp.2003.817973.
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Chen, L. H., and S. Jin. "Packaging of nanostructured microelectromechanical systems microtriode devices." Journal of Electronic Materials 32, no. 12 (December 2003): 1360–65. http://dx.doi.org/10.1007/s11664-003-0101-7.
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Kuntzman, Michael L., Karen D. Kirk, Caesar T. Garcia, Guclu A. Onaran, and Neal A. Hall. "Commercial packaging of an optical microelectromechanical systems microphone." Journal of the Acoustical Society of America 128, no. 4 (October 2010): 2444. http://dx.doi.org/10.1121/1.3508741.
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Su, Bingzhi, Y. C. Lee, and Martin L. Dunn. "Die Cracking at Solder (In60-Pb40) Joints on Brittle (GaAs) Chips: Fracture Correlation Using Critical Bimaterial Interface Corner Stress Intensities." Journal of Electronic Packaging 125, no. 3 (September 1, 2003): 369–77. http://dx.doi.org/10.1115/1.1602702.
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We study cracking from the interface of an In60-Pb40 solder joint on a brittle GaAs die when the joint is subjected to a uniform temperature change. Our primary objective is to apply and validate a fracture initiation criterion based on critical values of the stress intensities that arise from an analysis of the asymptotic elastic stress fields at the interface corner. In some regards the approach is similar to interface fracture mechanics; however, it differs in that it is based on a singular field other than that for a crack. We begin by determining the shape that the solder bump will assume after reflow when constrained by a fixed diameter wetting pad on the GaAs. To simplify the interpretation of the results, we focus on a class of solder bumps of various sizes, but with a self-similar shape. The approach, though, can be applied to different size and shape solder bumps. We then compute the asymptotic interface corner fields when the system is subjected to a uniform temperature change. The asymptotic structure (radial and angular dependence) of the elastic fields is computed analytically, and the corresponding stress intensities that describe the scaling of the elastic fields with geometry and loading are computed by axisymmetric finite element analysis. In order to assess the validity of fracture correlation using critical stress intensities, we designed and fabricated a series of test structures consisting of In60-Pb40 solder bumps on a GaAs chip. The test structures were subjected to uniform temperature drops from room temperature to induce cracking at the interface corner. From the tests we determined the relationship between the solder bump size and the temperature change at which cracking occurred. Not unexpectedly, smaller bumps required larger temperature changes to induce cracking. The observed scaling between solder bump size and temperature change is well described by the critical stress intensity failure criterion based on only a single parameter, the critical value of the mode 1 stress intensity, K1crn. Interestingly, this is because over a significant region, the mode 2 and constant terms in the asymptotic expansion cancel each other. This failure criterion provides the necessary machinery to construct failure maps in terms of geometry and thermomechanical loading. We conclude by describing how to apply the approach in more general and more practical settings that are possibly applicable to a wide range of problems in microelectronics, optoelectronics, and microelectromechanical systems packaging.
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Tadigadapa, Srinivas A., and Nader Najafi. "Developments in Microelectromechanical Systems (MEMS): A Manufacturing Perspective." Journal of Manufacturing Science and Engineering 125, no. 4 (November 1, 2003): 816–23. http://dx.doi.org/10.1115/1.1617286.
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This paper presents a discussion of some of the major issues that need to be considered for the successful commercialization of MEMS products. The diversity of MEMS devices and historical reasons have led to scattered developments in the MEMS manufacturing infrastructure. A good manufacturing strategy must include the complete device plan including package as part of the design and process development of the device. In spite of rapid advances in the field of MEMS there are daunting challenges that lie in the areas of MEMS packaging, and reliability testing. CAD tools for MEMS are starting to get more mature but are still limited in their overall performance. MEMS manufacturing is currently at a fragile state of evolution. In spite of all the wonderful possibilities, very few MEMS devices have been commercialized. In our opinion, the magnitude of the difficulty of fabricating MEMS devices at the manufacturing level is highly underestimated by both the current and emerging MEMS communities. A synopsis of MEMS manufacturing issues is presented here.
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Ortigoza-Diaz, Jessica, Kee Scholten, Christopher Larson, Angelica Cobo, Trevor Hudson, James Yoo, Alex Baldwin, Ahuva Weltman Hirschberg, and Ellis Meng. "Techniques and Considerations in the Microfabrication of Parylene C Microelectromechanical Systems." Micromachines 9, no. 9 (August 22, 2018): 422. http://dx.doi.org/10.3390/mi9090422.
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Parylene C is a promising material for constructing flexible, biocompatible and corrosion-resistant microelectromechanical systems (MEMS) devices. Historically, Parylene C has been employed as an encapsulation material for medical implants, such as stents and pacemakers, due to its strong barrier properties and biocompatibility. In the past few decades, the adaptation of planar microfabrication processes to thin film Parylene C has encouraged its use as an insulator, structural and substrate material for MEMS and other microelectronic devices. However, Parylene C presents unique challenges during microfabrication and during use with liquids, especially for flexible, thin film electronic devices. In particular, the flexibility and low thermal budget of Parylene C require modification of the fabrication techniques inherited from silicon MEMS, and poor adhesion at Parylene-Parylene and Parylene-metal interfaces causes device failure under prolonged use in wet environments. Here, we discuss in detail the promises and challenges inherent to Parylene C and present our experience in developing thin-film Parylene MEMS devices.
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Jin, Sungho. "Rare-earth-enabled universal solders for microelectromechanical systems and optical packaging." Journal of Electronic Materials 32, no. 12 (December 2003): 1366–70. http://dx.doi.org/10.1007/s11664-003-0102-6.
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Polla, D. L., and L. F. Francis. "Ferroelectric Thin Films in Micro-electromechanical Systems Applications." MRS Bulletin 21, no. 7 (July 1996): 59–65. http://dx.doi.org/10.1557/s0883769400035934.
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Ferroelectric ceramic thin films fit naturally into the burgeoning field of microelectromechanical systems (MEMS). Microelectromechanical systems combine traditional Si integrated-circuit (IC) electronics with micromechanical sensing and actuating components. The term MEMS has become synonymous with many types of microfabricated devices such as accelerometers, infrared detectors, flow meters, pumps, motors, and mechanical components. These devices have lateral dimensions in the range of 10 μm–10 mm. The ultimate goal of MEMS is a self-contained system of interrelated sensing and actuating devices together with signal processing and control electronics on a common substrate, most often Si. Since fabrication involves methods common to the IC industry, MEMS can be mass-produced. Commercial applications for MEMS already span biomedical (e.g., blood-pressure sensors), manufacturing (e.g., microflow controllers), information processing (e.g., displays), and automotive (e.g., accelerometers) industries. More applications are projected in consumer electronics, manufacturing control, communications, and aerospace. Materials for MEMS include traditional microelectronic materials (e.g., Si, SiO2, Si3N4, polyimide, Pt, Al) as well as nontraditional ones (e.g., ferroelectric ceramics, shapememory alloys, chemical-sensing materials). The superior piezoelectric and pyroelectric properties of ferroelectric ceramics make them ideal materials for microactuators and microsensors.
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Langfelder, Giacomo, Stefano Dellea, Federico Zaraga, Dario Cucchi, and Mikel Azpeitia Urquia. "The Dependence of Fatigue in Microelectromechanical Systems on the Environment and the Industrial Packaging." IEEE Transactions on Industrial Electronics 59, no. 12 (December 2012): 4938–48. http://dx.doi.org/10.1109/tie.2011.2151824.
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Love, J. Christopher, Janelle R. Anderson, and George M. Whitesides. "Fabrication of Three-Dimensional Microfluidic Systems by Soft Lithography." MRS Bulletin 26, no. 7 (July 2001): 523–28. http://dx.doi.org/10.1557/mrs2001.124.
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Two-dimensional (2D) methods for transferring patterns to planar substrates have enabled the technological revolution in microfabrication that has marked the last 40 years. The overall trend toward increased miniaturization has led to the development of new types of devices in areas unrelated to conventional microelectronics: analytical tools, chemical reactors, microelectromechanical systems (MEMS), optical systems, and sensors. The widespread use and high level of technological development associated with photolithography has also made the methodologies for microelectronics—patterning photosensitive polymers, etching and deposition of thin films, and liftoff—ubiquitous in the fabrication of these new classes of microsystems. These new systems have specialized requirements, however, and are not simple extensions of microelectronics technologies. They often require materials—especially organic polymers—that are not commonly used in microelectronic systems, they must have low cost, and they may need 3D structures in order to implement complex designs. These requirements have stimulated the development of new methods for microfabrication.
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Lin, Chih-Hsuan, Chao-Hung Song, and Kuei-Ann Wen. "Multi-Function Microelectromechanical Systems Implementation with an ASIC Compatible CMOS 0.18 μm Process." Micromachines 12, no. 3 (March 17, 2021): 314. http://dx.doi.org/10.3390/mi12030314.
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A multi-function microelectromechanical system (MEMS) with a three-axis magnetometer (MAG) and three-axis accelerometer (ACC) function was implemented with an application-specific integrated circuit (ASIC)-compatible complementary metal-oxide-semiconductor (CMOS) 0.18 μm process. The readout circuit used the nested chopper, correlated double-sampling (CDS), noise reduction method; the frequency division multiplexing method; the time-division multiplexing method; and the calibration method. Sensing was performed by exciting the MEMS three-axis magnetometer at X/Y/Z axes mechanical resonant frequencies of 3.77/7.05/7.47 kHz, respectively. A modest die-level vacuum packaging resulted in in-plane and out-of-plane mechanical quality factors of 471–500 and 971–1000, respectively. The sensitivities of both the three-axis magnetometer with 2 mA driving current and the three-axis accelerometer were 7.1–10.7 uV/uT and 58.37–88.87 uV/ug. The resolutions of both the three-axis magnetometer with 2 mA driving current and three-axis accelerometer resolution were 44.06–87.46 nT/√Hz and 5.043–7.5 ng/√Hz. The resolution was limited by circuit noise equivalent acceleration (CNEM) and Brownian noise equivalent magnetic field (BNEM).
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Suga, Tadatomo. "Comparative annealing effect on bonded wafers in air and ultrahigh vacuum for microelectromechanical systems/microfluidics packaging." Journal of Micro/Nanolithography, MEMS, and MOEMS 9, no. 4 (October 1, 2010): 041107. http://dx.doi.org/10.1117/1.3500747.
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Luc Le, Xuan, Han Eul Lee, and Sung-Hoon Choa. "Deformation Behavior of Various Interconnection Structures Using Fine Pitch Microelectromechanical Systems (MEMS) Vertical Probe." Journal of Nanoscience and Nanotechnology 21, no. 5 (May 1, 2021): 2949–58. http://dx.doi.org/10.1166/jnn.2021.19132.
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Recently, fine pitch wafer level packaging (WLP) technologies have drawn a great attention in the semiconductor industries. WLP technology uses various interconnection structures including microbumps and through-silicon-vias (TSVs). To increase yield and reduce cost, there is an increasing demand for wafer level testing. Contact behavior between probe and interconnection structure is a very important factor affecting the reliability and performance of wafer testing. In this study, with a MEMS vertical probe, we performed systematic numerical analysis of the deformation behavior of various interconnection structures, including solder bump, copper (Cu) pillar bump, solder capper Cu bump, and TSV. During probing, the solder ball showed the largest deformation. The Cu pillar bump also exhibited relatively large deformation. The Cu bump began to deform at OD of 10 μm. At OD of 20 μm, bump pillar was compressed, and the height of the bump decreased by 8.3%. The deformation behavior of the solder capped Cu bump was similar to that of the solder ball. At OD of 20 μm, the solder and Cu bumps were largely deformed, and the total height was reduced by 11%. The TSV structure showed the lowest deformation, but exerted the largest stress on the probe. In particular, copper protrusion at the outer edge of the via was observed, and very large shear stress was generated between the via and the silicon oxide layer. In summary, when probing various interconnection structures, the probe stress is less than that when using an aluminum pad. On the other hand, deformation of the structure is a critical issue. In order to minimize damage to the interconnection structure, smaller size probes or less overdrive should be used. This study will provide important guidelines for performing wafer-level testing and minimizing damage of probes and interconnection structures.
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Yang, In-Hwan, Joon-Hyung Jin, and Nam Ki Min. "A Micromachined Metal Oxide Composite Dual Gas Sensor System for Principal Component Analysis-Based Multi-Monitoring of Noxious Gas Mixtures." Micromachines 11, no. 1 (December 24, 2019): 24. http://dx.doi.org/10.3390/mi11010024.
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Microelectronic gas-sensor devices were developed for the detection of carbon monoxide (CO), nitrogen dioxides (NO2), ammonia (NH3) and formaldehyde (HCHO), and their gas-sensing characteristics in six different binary gas systems were examined using pattern-recognition methods. Four nanosized gas-sensing materials for these target gases, i.e., Pd-SnO2 for CO, In2O3 for NOX, Ru-WO3 for NH3, and SnO2-ZnO for HCHO, were synthesized using a sol-gel method, and sensor devices were fabricated using a microsensor platform. Principal component analysis of the experimental data from the microelectromechanical systems gas-sensor arrays under exposure to single gases and their mixtures indicated that identification of each individual gas in the mixture was successful. Additionally, the gas-sensing behavior toward the mixed gas indicated that the traditional adsorption and desorption mechanism of the n-type metal oxide semiconductor (MOS) governs the sensing mechanism of the mixed gas systems.
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Park, Woo-Tae, Jin-Wook Jang, Troy Clare, and Lianjun Liu. "Microstructure and mechanical properties of aluminum–germanium eutectic bonding with polysilicon metallization for microelectromechanical systems (MEMS) packaging." Scripta Materialia 64, no. 8 (April 2011): 733–36. http://dx.doi.org/10.1016/j.scriptamat.2010.12.024.
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Phinney, L. M., and Chang-Lin Tien. "Electronic Desorption of Surface Species Using Short-Pulse Lasers." Journal of Heat Transfer 120, no. 3 (August 1, 1998): 765–71. http://dx.doi.org/10.1115/1.2824348.
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New methods of removing surface contaminants from microelectronic and microelectromechanical systems (MEMS) devices are needed since the decreasing size of their components is reducing the allowable contamination levels. By choosing the pulse duration and fluence to optimize electronic rather than thermal desorption in short-pulse laser processing, surface species can be removed without exceeding maximum temperature constraints. A two-temperature model for short-pulse laser heating of, and subsequent desorption from, metal surfaces is presented. A scaling analysis indicates the material properties and laser parameters on which the ratio of electronic to thermal desorption depends. Regimes of predominantly electronic and thermal desorption are identified, and predicted desorption yields from gold films show that electronic desorption is the primary desorption mechanism in certain short-pulse laser processes.
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Samotaev, Nikolay, Konstantin Oblov, Maya Etrekova, Denis Veselov, and Anastasiya Gorshkova. "Parameter Studies of Ceramic MEMS Microhotplates Fabricated by Laser Micromilling Technology." Materials Science Forum 977 (February 2020): 238–43. http://dx.doi.org/10.4028/www.scientific.net/msf.977.238.
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This paper presents a modeling of technology aspects for fabrication ceramic microelectromechanical systems (MEMS) microhotplate and surface mounting device (SMD) packaging for (MOX) gas sensors applications. Innovative claims include: demonstration of flexible opportunities for new fabrication process flows based on laser micromilling tech; modeling of power consumption MEMS microhotplate depending on the thickness and topology; demonstration of necessity changing thick film technology of metallization to vacuum sputtering by reducing of power consumption. The results show possibility to fast fabrication of different topologies for ceramic MEMS microhotplate in form-factor of SOT-23 type SMD package.
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Prochazka, Huber, Dobrev, Harris, Dalbert, Röösli, Obrist, and Pfiffner. "Packaging Technology for an Implantable Inner Ear MEMS Microphone." Sensors 19, no. 20 (October 16, 2019): 4487. http://dx.doi.org/10.3390/s19204487.
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Current cochlear implant (CI) systems provide substantial benefits for patients with severe hearing loss. However, they do not allow for 24/7 hearing, mainly due to the external parts that cannot be worn in all everyday situations. One of the key missing parts for a totally implantable CI (TICI) is the microphone, which thus far has not been implantable. The goal of the current project was to develop a concept for a packaging technology for state-of-the-art microelectromechanical systems (MEMS) microphones that record the liquid-borne sound inside the inner ear (cochlea) as a microphone signal input for a TICI. The packaging concept incorporates requirements, such as biocompatibility, long-term hermeticity, a high sensing performance and a form factor that allows sensing inside the human cochlea and full integration into the existing CI electrode array. The present paper (1) describes the sensor packaging concept and the corresponding numerical and experimental design verification process and (2) gives insight into new engineering solutions for sensor packaging. Overall, a packaging concept was developed that enables MEMS microphone technology to be used for a TICI system.
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Roshanghias, Ali, Marc Dreissigacker, Christina Scherf, Christian Bretthauer, Lukas Rauter, Johanna Zikulnig, Tanja Braun, Karl-F. Becker, Sven Rzepka, and Martin Schneider-Ramelow. "On the Feasibility of Fan-Out Wafer-Level Packaging of Capacitive Micromachined Ultrasound Transducers (CMUT) by Using Inkjet-Printed Redistribution Layers." Micromachines 11, no. 6 (May 31, 2020): 564. http://dx.doi.org/10.3390/mi11060564.
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Fan-out wafer-level packaging (FOWLP) is an interesting platform for Microelectromechanical systems (MEMS) sensor packaging. Employing FOWLP for MEMS sensor packaging has some unique challenges, while some originate merely from the fabrication of redistribution layers (RDL). For instance, it is crucial to protect the delicate structures and fragile membranes during RDL formation. Thus, additive manufacturing (AM) for RDL formation seems to be an auspicious approach, as those challenges are conquered by principle. In this study, by exploiting the benefits of AM, RDLs for fan-out packaging of capacitive micromachined ultrasound transducers (CMUT) were realized via drop-on-demand inkjet printing technology. The long-term reliability of the printed tracks was assessed via temperature cycling tests. The effects of multilayering and implementation of an insulating ramp on the reliability of the conductive tracks were identified. Packaging-induced stresses on CMUT dies were further investigated via laser-Doppler vibrometry (LDV) measurements and the corresponding resonance frequency shift. Conclusively, the bottlenecks of the inkjet-printed RDLs for FOWLP were discussed in detail.
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Mauri, Luca, Anna Della Porta, Alessio Corazza, and Marco Moraja. "Vacuum Packaging Requirements for MEMS and Characterization Techniques." Proceedings 56, no. 1 (December 15, 2020): 18. http://dx.doi.org/10.3390/proceedings2020056018.
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Getter materials are technically proven and industrially well-implemented solutions for maintaining a vacuum inside electronic devices to assure long lifetimes and proper operating conditions. The pressure requirements of some hermetically packaged microelectromechanical systems (MEMS) devices, such as gyroscopes, accelerometers, infrared (IR) bolometers, and digital mirrors, are very stringent. The internal pressure can be as low as in the 10−3 mbar range. Due to the desorption phenomena of gaseous species from the internal surfaces, the vacuum inside such hermetically sealed electronic devices tends to degrade over time and, in the worst case, can affect the proper operation of the device. The integration of a special nanostructured getter film is an effective way to preserve and guarantee the performance of such devices. In addition to the getter material, there is also the need to develop and customize analytical techniques for post-process vacuum quality control and reliability checks of hermetic bonding, which are extremely important for the assessment of a device’s overall performance, lifetime, and manufacturing process yield.
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DeGaspari, John. "Pumped Up." Mechanical Engineering 127, no. 04 (April 1, 2005): 34–39. http://dx.doi.org/10.1115/1.2005-apr-2.
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This article focuses on microelectromechanical systems that have been one of the hot topics of the engineering world for years now. Tire-pressure monitoring systems have been available on select passenger vehicles since the late 1990s. Tire-pressure sensor modules contain several components. A MEMS pressure sensor is the key element, but the package may also include a temperature sensor, voltage sensor, accelerometer, microcontroller, radio-frequency circuit, antenna, and battery. Some suppliers of MEMS tire-pressure sensors are seeking to eliminate batteries and power the tire-pressure sensing module by an alternative power source. In the sensor module, packaging must expose the sensor to air pressure and protect the rest of the components. Freescale, for example, protects its sensor with a Teflon filter, which makes sure that only dry air can enter and pressurize the diaphragm.
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Thang, Nguyen Van, Pham Manh Thang, and Tran Duc Tan. "The performance improvement of a lowcost INS/GPS integration system using the street return algorithm." Vietnam Journal of Mechanics 34, no. 4 (November 30, 2012): 271–80. http://dx.doi.org/10.15625/0866-7136/34/4/2337.
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During the last decades, MEMS technology has undergone rapidly development, leading to the successful fabrication of miniaturized mechanical structures integrated with microelectronic components. Accelerometers and gyroscopes are in great demand for specific applications ranging from guidance and stabilization of spacecraft to research on vibrations of Parkinson patient’s fingers. The demand of navigation and guidance has been urgent for many years. In fact, INS is used daily in flight dynamics control. Nowadays, with the strong growth of Microelectromechanical system (MEMS) technology, the Inertial Navigation Systems are applied widely. However, there are existing errors in the accelerometer and gyroscope signals that cause unacceptable drifts. Even when the Inertial Navigation System (INS) was supported by the Global Positioning System (GPS), the position error is still large, especially in the case of GPS signal lost. In this paper, we will present a simple algorithm called Street Return Algorithm(SRA) to reduce this kind of error. Experimental result showed that this algorithm could be applied in the real-time operation.
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Gooch, Roland, and Thomas Schimert. "Low-Cost Wafer-Level Vacuum Packaging for MEMS." MRS Bulletin 28, no. 1 (January 2003): 55–59. http://dx.doi.org/10.1557/mrs2003.18.
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AbstractVacuum packaging of high-performance surface-micromachined uncooled microbolometer detectors and focal-plane arrays (FPAs) for infrared imaging and nonimaging applications, inertial MEMS (microelectromechanical systems) accelerometers and gyroscopes, and rf MEMS resonators is a key issue in the technology development path to low-cost, high-volume MEMS production. In this article, two approaches to vacuum packaging for MEMS will be discussed. The first is component-level vacuum packaging, a die-level approach that involves packaging individual die in a ceramic package using either a silicon or germanium lid. The second approach is wafer-level vacuum packaging, in which the vacuum-packaging process is carried out at the wafer level prior to dicing the wafer into individual die. We focus the discussion of MEMS vacuum packaging on surface-micromachined uncooled amorphous silicon infrared microbolometer detectors and FPAs for which both component-level and wafer-level vacuum packaging have found widespread application and system insertion. We first discuss the requirement for vacuum packaging of uncooled a-Si microbolometers and FPAs. Second, we discuss the details of the component-level and wafer-level vacuum-packaging approaches. Finally, we discuss the system insertion of wafer-level vacuum packaging into the Raytheon 2000AS uncooled infrared imaging camera product line that employs a wafer-level-packaged 160 × 120 pixel a-Si infrared FPA.
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Meng, Cheng, Yang, Sun, and Luo. "A Novel Seedless TSV Process Based on Room Temperature Curing Silver Nanowires ECAs for MEMS Packaging." Micromachines 10, no. 6 (May 28, 2019): 351. http://dx.doi.org/10.3390/mi10060351.
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The through-silicon-vias (TSVs) process is a vital technology in microelectromechanical systems (MEMS) packaging. The current via filling technique based on copper electroplating has many shortcomings, such as involving multi-step processes, requiring sophisticated equipment, low through-put and probably damaging the MEMS devices susceptible to mechanical polishing. Herein, a room temperature treatable, high-efficient and low-cost seedless TSV process was developed with a one-step filling process by using novel electrically conductive adhesives (ECAs) filled with silver nanowires. The as-prepared ECAs could be fully cured at room temperature and exhibited excellent conductivity due to combining the benefits of both polymethyl methacrylate (PMMA) and silver nanowires. Complete filling of TSVs with the as-prepared 30 wt% silver nanowires ECAs was realized, and the resistivity of a fully filled TSV was as low as 10−3 Ω·cm. Furthermore, the application of such novel TSV filling process could also be extended to a wide range of different substrates, showing great potential in MEMS packaging, flexible microsystems and many other applications.
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Yamamoto, Michitaka, Takashi Matsumae, Yuichi Kurashima, Hideki Takagi, Tadatomo Suga, Seiichi Takamatsu, Toshihiro Itoh, and Eiji Higurashi. "Effect of Au Film Thickness and Surface Roughness on Room-Temperature Wafer Bonding and Wafer-Scale Vacuum Sealing by Au-Au Surface Activated Bonding." Micromachines 11, no. 5 (April 27, 2020): 454. http://dx.doi.org/10.3390/mi11050454.
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Au-Au surface activated bonding (SAB) using ultrathin Au films is effective for room-temperature pressureless wafer bonding. This paper reports the effect of the film thickness (15–500 nm) and surface roughness (0.3–1.6 nm) on room-temperature pressureless wafer bonding and sealing. The root-mean-square surface roughness and grain size of sputtered Au thin films on Si and glass wafers increased with the film thickness. The bonded area was more than 85% of the total wafer area when the film thickness was 100 nm or less and decreased as the thickness increased. Room-temperature wafer-scale vacuum sealing was achieved when Au thin films with a thickness of 50 nm or less were used. These results suggest that Au-Au SAB using ultrathin Au films is useful in achieving room-temperature wafer-level hermetic and vacuum packaging of microelectromechanical systems and optoelectronic devices.
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Brown, Stuart B. "A Little Knowledge." Mechanical Engineering 125, no. 10 (October 1, 2003): 48–51. http://dx.doi.org/10.1115/1.2003-oct-2.
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This article explains microelectromechanical systems (MEMS) design concepts that are under investigation for their application in different domains. MEMS provide numerous performance advantages. Miniaturization improves packaging and simplifies installation and maintenance. Power consumption can drop dramatically. Analysis shows that appropriate hermeticity and cleanliness remain a challenge, because sufficient contamination to introduce frequency drift may result from the migration of trace contaminants within a package itself. Many reliability issues apply to different MEMS in diverse ways. Work to date indicates that low-stress, hermetically packaged devices pose little concern about crack growth. The increasing maturity of MEMS and the emphasis on reliability represents good news for the industry, as it reflects the natural evolution from initial product design to fabrication technologies to long-term reliability. Despite current challenges, there is no fundamental constraint to reliability improvements as our knowledge of failure mechanisms and countermeasures increases.
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Qiu, Zhen, and Wibool Piyawattanametha. "MEMS Actuators for Optical Microendoscopy." Micromachines 10, no. 2 (January 24, 2019): 85. http://dx.doi.org/10.3390/mi10020085.
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Growing demands for affordable, portable, and reliable optical microendoscopic imaging devices are attracting research institutes and industries to find new manufacturing methods. However, the integration of microscopic components into these subsystems is one of today’s challenges in manufacturing and packaging. Together with this kind of miniaturization more and more functional parts have to be accommodated in ever smaller spaces. Therefore, solving this challenge with the use of microelectromechanical systems (MEMS) fabrication technology has opened the promising opportunities in enabling a wide variety of novel optical microendoscopy to be miniaturized. MEMS fabrication technology enables abilities to apply batch fabrication methods with high-precision and to include a wide variety of optical functionalities to the optical components. As a result, MEMS technology has enabled greater accessibility to advance optical microendoscopy technology to provide high-resolution and high-performance imaging matching with traditional table-top microscopy. In this review the latest advancements of MEMS actuators for optical microendoscopy will be discussed in detail.
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DeGaspari, John. "Beyond Silicon." Mechanical Engineering 127, no. 07 (July 1, 2005): 30–33. http://dx.doi.org/10.1115/1.2005-jul-2.
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This article highlights that engineers are expanding their material world to reduce the cost and tailor performance of microdevices. Microelectromechanical systems evolved from the semiconductor industry, and silicon accounts for the vast majority of MEMS. This is not a surprise, since silicon lends itself well to semiconductor processing, and the designers and engineers of integrated circuits and MEMS understand the material’s characteristics and how to process it. Researchers at the University of California, Santa Barbara, meanwhile, are investigating the use of titanium as a wafer material for MEMS. Noel MacDonald, who heads the research group, said that titanium has advantages over silicon with regard to packaging, material properties, and the ability to create three-dimensional structures. Silicon is sure to be a material of choice among MEMS designers for a long time. But the availability of new materials, both for MEMS themselves and tooling to form microstructures, will open doors for new applications.
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Zhang, Meng, Jian Yang, Yurong He, Fan Yang, Fuhua Yang, Guowei Han, Chaowei Si, and Jin Ning. "Research on a 3D Encapsulation Technique for Capacitive MEMS Sensors Based on Through Silicon Via." Sensors 19, no. 1 (December 28, 2018): 93. http://dx.doi.org/10.3390/s19010093.
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A novel three-dimensional (3D) hermetic packaging technique suitable for capacitive microelectromechanical systems (MEMS) sensors is studied. The composite substrate with through silicon via (TSV) is used as the encapsulation cap fabricated by a glass-in-silicon (GIS) reflow process. In particular, the low-resistivity silicon pillars embedded in the glass cap are designed to serve as the electrical feedthrough and the fixed capacitance plate at the same time to simplify the fabrication process and improve the reliability. The fabrication process and the properties of the encapsulation cap were studied systematically. The resistance of the silicon vertical feedthrough was measured to be as low as 263.5 mΩ, indicating a good electrical interconnection property. Furthermore, the surface root-mean-square (RMS) roughnesses of glass and silicon were measured to be 1.12 nm and 0.814 nm, respectively, which were small enough for the final wafer bonding process. Anodic bonding between the encapsulation cap and the silicon wafer with sensing structures was conducted in a vacuum to complete the hermetic encapsulation. The proposed packaging scheme was successfully applied to a capacitive gyroscope. The quality factor of the packaged gyroscope achieved above 220,000, which was at least one order of magnitude larger than that of the unpackaged. The validity of the proposed packaging scheme could be verified. Furthermore, the packaging failure was less than 1%, which demonstrated the feasibility and reliability of the technique for high-performance MEMS vacuum packaging.
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Bai, Dongshun, Michelle Fowler, Curtis Planje, and Xie Shao. "Planarization of Deep Structures Using Self-Leveling Materials." International Symposium on Microelectronics 2012, no. 1 (January 1, 2012): 000079–83. http://dx.doi.org/10.4071/isom-2012-ta32.
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To achieve device integration that will allow the manufacture of smaller, more functional, and more efficient microelectronics, the industry increasingly requires materials to fill and planarize devices with deep structures. Brewer Science has developed several new self-leveling materials to address these planarization needs. These newly developed materials are designed to be either temporary materials that can be removed after their use in processing steps or permanent materials that can stay in a device for its lifetime. These new materials can be applied easily by means of a spin-coating process. They are unique because they can fill and planarize high-aspect-ratio trenches and vias hundreds of microns deep. Some of the materials are photosensitive and can be patterned using photolithography. All of the photosensitive materials in this paper can be developed with industry-accepted solvents and some with an aqueous TMAH solution. Because of their good thermal stability, high transparency, and excellent planarization properties, these materials have potential applications for microelectromechanical systems (MEMS), 3-D integrated circuits, light-emitting diodes (LEDs), semiconductors, flat-panel displays, and related microelectronic and optoelectronic devices. This paper will discuss the properties of these new materials and will present the filling and leveling results obtained in several applications.
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Weiss, Jonathan D. "Magnetic Force and Thermal Expansion as Failure Mechanisms of Electrothermal MEMS Actuators Under Electrostatic Discharge Testing." Journal of Applied Mechanics 74, no. 5 (January 31, 2007): 996–1005. http://dx.doi.org/10.1115/1.2723813.
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Like microelectronic circuits, microelectromechanical systems (MEMS) devices are susceptible to damage by electrostatic discharge (ESD). At Sandia National Laboratories, polysilicon electrothermal MEMS actuators have been subjected to ESD pulses to examine that susceptibility. Failures, in the form of cracks at points of high stress concentration, occurred that could not be explained by thermal degradation of the polysilicon caused by excessive heating, or by excessive displacement of the legs of the actuator of the same nature that occur in normal operation. One hypothesis presented in this paper is that the internal magnetic forces between the legs of the actuator, resulting from the ESD-associated high current pulses, might produce vibrations of amplitude sufficient to produce these cracks. However, a dynamic analysis based on simple beam theory indicated that such cracks are unlikely to occur, except under rather extreme conditions. On the other hand, these same current pulses also cause resistive heating of the legs and, therefore, thermally induced compression that can lead to buckling. Buckling stresses, particularly when augmented by magnetic forces, can readily explain failure. Both the magnetic and thermal analyses were performed using the human body model and the machine model of ESD. A justification for ignoring shuttle motion and eddy currents induced in the substrate during the ESD pulse is presented, as well.
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Jiang, Bo, Yan Su, Guowen Liu, Lemin Zhang, and Fumin Liu. "A High Q-Factor Outer-Frame-Anchor Gyroscope Operating at First Resonant Mode." Micromachines 11, no. 12 (December 1, 2020): 1071. http://dx.doi.org/10.3390/mi11121071.
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Disc gyroscope manufactured through microelectromechanical systems (MEMS) fabrication processes becomes one of the most critical solutions for achieving high performance. Some reported novel disc constructions acquire good performance in bias instability, scale factor nonlinearity, etc. However, antivibration characteristics are also important for the devices, especially in engineering applications. For multi-ring structures with central anchors, the out-of-plane motions are in the first few modes, easily excited within the vibration environment. The paper presents a multi-ring gyro with good dynamic characteristics, operating at the first resonant mode. The design helps obtain better static performance and antivibration characteristics with anchor points outside of the multi-ring resonator. According to harmonic experiments, the nearest interference mode is located at 30,311 Hz, whose frequency difference is 72.8% far away from working modes. The structures were fabricated with silicon on insulator (SOI) processes and wafer-level vacuum packaging, where the asymmetry is 780 ppm as the frequency splits. The gyro also obtains a high Q-factor. The measured value at 0.15 Pa was 162 k, which makes the structure have sizeable mechanical sensitivity and low noise.
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Gan, Zhenghao, Changzheng Wang, and Zhong Chen. "Material Structure and Mechanical Properties of Silicon Nitride and Silicon Oxynitride Thin Films Deposited by Plasma Enhanced Chemical Vapor Deposition." Surfaces 1, no. 1 (August 30, 2018): 59–72. http://dx.doi.org/10.3390/surfaces1010006.
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Silicon nitride and silicon oxynitride thin films are widely used in microelectronic fabrication and microelectromechanical systems (MEMS). Their mechanical properties are important for MEMS structures; however, these properties are rarely reported, particularly the fracture toughness of these films. In this study, silicon nitride and silicon oxynitride thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) under different silane flow rates. The silicon nitride films consisted of mixed amorphous and crystalline Si3N4 phases under the range of silane flow rates investigated in the current study, while the crystallinity increased with silane flow rate in the silicon oxynitride films. The Young’s modulus and hardness of silicon nitride films decreased with increasing silane flow rate. However, for silicon oxynitride films, Young’s modulus decreased slightly with increasing silane flow rate, and the hardness increased considerably due to the formation of a crystalline silicon nitride phase at the high flow rate. Overall, the hardness, Young modulus, and fracture toughness of the silicon nitride films were greater than the ones of silicon oxynitride films, and the main reason lies with the phase composition: the SiNx films were composed of a crystalline Si3N4 phase, while the SiOxNy films were dominated by amorphous Si–O phases. Based on the overall mechanical properties, PECVD silicon nitride films are preferred for structural applications in MEMS devices.
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Huemoeller, Ron. "Creating Semiconductor Value through Advanced Package Technology." International Symposium on Microelectronics 2016, S1 (October 1, 2016): S1—S46. http://dx.doi.org/10.4071/isom-2016-slide-1.
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Over the past few years, there has been a significant shift from PCs and notebooks to smartphones and tablets as drivers of advanced packaging innovation. In fact, the overall packaging industry is doing quite well today as a result, with solid growth expected to create a market value in excess of $30B USD by 2020. This is largely due to the technology innovation in the semiconductor industry continuing to march forward at an incredible pace, with silicon advancements in new node technologies continuing on one end of the spectrum and innovative packaging solutions coming forward on the other in a complementary fashion. The pace of innovation has quickened as has the investments required to bring such technologies to production. At the packaging level, the investments required to support the advancements in silicon miniaturization and heterogeneous integration have now reached well beyond $500M USD per year. Why has the investment to support technology innovation in the packaging community grown so much? One needs to look no further than the complexity of the most advanced package technologies being used today and coming into production over the next year. Advanced packaging technologies have increased in complexity over the years, transitioning from single to multi-die packaging, enabled by 3-dimensional integration, system-in-package (SiP), wafer-level packaging (WLP), 2.5D/3D technologies and creative approached to embedding die. These new innovative packaging technologies enable more functionality and offer higher levels of integration within the same package footprint, or even more so, in an intensely reduced footprint. In an industry segment that has grown accustomed to a multitude of package options, technology consolidation seems evident, producing “The Big Five” advanced packaging platforms. These include low-cost flip chip, wafer-level chip-scale package (WLCSP), microelectromechanical systems (MEMS), laminate-based advanced system-in-package (SiP) and wafer-based advanced SiP designs. This presentation will address ‘The Big Five’ packaging platforms and how they are adding value to the Semiconductor Industry.
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Hadizadeh, Rameen, Anssi Laitinen, Niko Kuusniemi, Volker Blaschke, David Molinero, Eoin O'Toole, and Márcio Pinheiro. "Low-Density Fan-Out Heterogeneous Integration of MEMS Tunable Capacitor and RF SOI Switch." International Symposium on Microelectronics 2019, no. 1 (October 1, 2019): 000051–55. http://dx.doi.org/10.4071/2380-4505-2019.1.000051.
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Abstract Using Low-Density Fan-Out (LDFO) packaging technology, a radio frequency (RF) microelectromechanical systems (MEMS) tunable capacitor array composed of electrostatically actuated beams on 180nm high-voltage CMOS silicon was heterogeneously integrated with a single-pole four-terminal (SP4T) RF switch on 180nm CMOS silicon-on-insulator (SOI). The primary objective of this study was to determine the manufacturability of this System-in-Package (SiP) design, which is proven at time zero through survival of the MEMS device based on acceptable MEMS performance metrics. In addition, the RF SOI switch provides high-voltage electrostatic discharge (ESD) protection for the MEMS device. Capacitive MEMS structures are particularly sensitive to unpredictable electrostatic charging scenarios, such as handling after package assembly and printed circuit board (PCB) surface mount processing. Consequently, resistance to dielectric breakdown by means of robust ESD protection is a very desirable quality. Integrating the RF switch in close proximity with the MEMS device not only enables the ability to withstand charging scenarios in excess of 1kV (human body model), it mitigates the impact of parasitics on RF performance by minimizing interconnect lengths and complexity.
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Inomata, Naoki, Masaya Toda, and Takahito Ono. "Microfabricated Temperature-Sensing Devices Using a Microfluidic Chip for Biological Applications." International Journal of Automation Technology 12, no. 1 (January 5, 2018): 15–23. http://dx.doi.org/10.20965/ijat.2018.p0015.
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Microelectromechanical systems (MEMS) and micrototal analysis systems (μTAS) have been developed using microfabrication technologies. As MEMS and μTAS contribute to smaller, higher-performance, less expensive, and integrated sensing techniques, they have been applied in many fields. In this paper, we focus on microfabricated thermal detection devices, including a microthermistor fabricated using vanadium oxide (VOx) and a resonant thermal sensor integrated into a microfluidic chip, and we present the research work we have done into biological applications, applications using a unique material and detection method for liquid samples. The VOx thermistor, which has a high temperature coefficient of resistance at –1.3%/K, is mounted onto a thermally insulated membrane in the microfluidic chip. This device is used to detect glucose and cholesterol concentrations in solutions. The resonant thermal sensor is another candidate for obtaining highly sensitive thermal measurements; however, this sensor is difficult to use with liquids because of vibration damping and thermal loss. To solve these problems, we propose a partial vacuum packaging system for the sensor in the microfluidic chip. This technique, which involves silicon resonators, was used to successfully detect the heat from a single brown fat cell. Moreover, the possibility of using a VOx resonant thermal sensor is discussed. The future prospects for MEMS and automation technology are described, with a focus on the Internet of Things/big data for medical and healthcare applications.
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Sharma, Kohli, Brière, Ménard, and Nabki. "Translational MEMS Platform for Planar Optical Switching Fabrics." Micromachines 10, no. 7 (June 30, 2019): 435. http://dx.doi.org/10.3390/mi10070435.
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While 3-D microelectromechanical systems (MEMS) allow switching between a large number of ports in optical telecommunication networks, the development of such systems often suffers from design, fabrication and packaging constraints due to the complex structures, the wafer bonding processes involved, and the tight alignment tolerances between different components. In this work, we present a 2-D translational MEMS platform capable of highly efficient planar optical switching through integration with silicon nitride (SiN) based optical waveguides. The discrete lateral displacement provided by simple parallel plate actuators on opposite sides of the central platform enables switching between different input and output waveguides. The proposed structure can displace the central platform by 3.37 µm in two directions at an actuation voltage of 65 V. Additionally, the parallel plate actuator designed for closing completely the 4.26 µm air gap between the fixed and moving waveguides operates at just 50 V. Eigenmode expansion analysis shows over 99% butt-coupling efficiency the between the SiN waveguides when the gap is closed. Also, 2.5 finite-difference time-domain analysis demonstrates zero cross talk between two parallel SiN waveguides across the length of the platform for a 3.5 µm separation between adjacent waveguides enabling multiple waveguide configuration onto the platform. Different MEMS designs were simulated using static structural analysis in ANSYS. These designs were fabricated with a custom process by AEPONYX Inc. (Montreal, QC, Canada) and through the PiezoMUMPs process of MEMSCAP (Durham, NC, USA).
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N.S., Shashikumar, Gireesha B.J., B. Mahanthesh, and Prasannakumara B.C. "Brinkman-Forchheimer flow of SWCNT and MWCNT magneto-nanoliquids in a microchannel with multiple slips and Joule heating aspects." Multidiscipline Modeling in Materials and Structures 14, no. 4 (December 3, 2018): 769–86. http://dx.doi.org/10.1108/mmms-01-2018-0005.
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Purpose The microfluidics has a wide range of applications, such as micro heat exchanger, micropumps, micromixers, cooling systems for microelectronic devices, fuel cells and microturbines. However, the enhancement of thermal energy is one of the challenges in these applications. Therefore, the purpose of this paper is to enhance heat transfer in a microchannel flow by utilizing carbon nanotubes (CNTs). MHD Brinkman-Forchheimer flow in a planar microchannel with multiple slips is considered. Aspects of viscous and Joule heating are also deployed. The consequences are presented in two different carbon nanofluids. Design/methodology/approach The governing equations are modeled with the help of conservation equations of flow and energy under the steady-state situation. The governing equations are non-dimensionalized through dimensionless variables. The dimensionless expressions are treated via Runge-Kutta-Fehlberg-based shooting scheme. Pertinent results of velocity, skin friction coefficient, temperature and Nusselt number for assorted values of physical parameters are comprehensively discussed. Also, a closed-form solution is obtained for momentum equation for a particular case. Numerical results agree perfectly with the analytical results. Findings It is established that multiple slip effect is favorable for velocity and temperature fields. The velocity field of multi-walled carbon nanotubes (MWCNTs) nanofluid is lower than single-walled carbon nanotubes (SWCNTs)-nanofluid, while thermal field, Nusselt number and drag force are higher in the case of MWCNT-nanofluid than SWCNT-nanofluid. The impact of nanotubes (SWCNTs and MWCNTs) is constructive for thermal boundary layer growth. Practical implications This study may provide useful information to improve the thermal management of microelectromechanical systems. Originality/value The effects of CNTs in microchannel flow by utilizing viscous dissipation and Joule heating are first time investigated. The results for SWCNTs and MWCNTs have been compared.
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Maboudian, Roya. "Adhesion and Friction Issues Associated With Reliable Operation of MEMS." MRS Bulletin 23, no. 6 (June 1998): 47–51. http://dx.doi.org/10.1557/s0883769400030633.
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A growing interest exists in developing technologies that use silicon and other electronic materials as mechanical materials. Using standard processes of the integrated-circuit industry, researchers have successfully fabricated miniature mechanical components (micromachines) such as membranes, gears, motors, pumps, and valves. The integration of miniaturized mechanical components with microelectronic components has spawned a new technology known as microelectromechanical systems (MEMS). It promises to extend the benefits of microelectronic fabrication to sensing and actuating functions. Early applications of this technology include the digital mirror display, which has of the order of 106 aluminum thin-film micromirrors fabricated on top of a complementary-metal-oxide-semiconductor static random-access-memory integrated circuit. Other applications include integrated accelerometers for tasks such as air-bag deployment.A number of fabrication techniques have been developed for this technology and have been reviewed elsewhere. In this review, I focus on surface-micromachining technology and adhesion and friction problems in surface-micromachined polycrystalline silicon (polysilicon) structures, though many of the principles discussed will also apply both to single-crystalline silicon and nonsilicon-based structures. Surface micromachining, defined as the fabrication of micromechanical structures from deposited thin films, is one of the core technological processes underlying MEMS. Surface microstructures have lateral dimensions of 50-500 μm with thicknesses of 0.1–2.5 μm and are offset 0.1–2 μm from the substrate. The basic steps in a surface-micromachining process appear in Figure 1. First the substrate is typically coated with an isolation layer (Figure la) that protects it during subsequent etching steps. A sacrificial layer is then deposited on the substrate and patterned. For simplicity, Figure 1b shows that the opening of the sacrificial layer is terminated on the isolation layer. The microstructural thin film is then deposited and etched (Figure 1c). Finally selective etching of the sacrificial layer creates the freestanding micromechanical structures such as the cantilever beam shown in cross section in Figure 1d. The technique can be extended to make multiple-layer microstructures.
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Pei, Binbin, Ke Sun, Heng Yang, Chaozhan Ye, Peng Zhong, Tingting Yu, and Xinxin Li. "Oven-Controlled MEMS Oscillator with Integrated Micro-Evaporation Trimming." Sensors 20, no. 8 (April 22, 2020): 2373. http://dx.doi.org/10.3390/s20082373.
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This study reports an oven-controlled microelectromechanical systems oscillator with integrated micro-evaporation trimming that achieves frequency stability over the industrial temperature range and permanent frequency trimming after vacuum packaging. The length-extensional-mode resonator is micro-oven controlled and doped degenerately with phosphorous to achieve a frequency instability of ±2.6 parts per million (ppm) in a temperature range of −40 to 85 °C. The micro-evaporators are bonded to the resonator, integrated face-to-face, and encapsulated in vacuum. During trimming, the micro-evaporators are heated electrically, and the aluminum layers on their surfaces are evaporated and deposited on the surface of the resonator that trims the resonant frequency of the resonator permanently. The impact of the frequency trimming on the temperature stability is very small. The temperature drift increases from ±2.6 ppm within the industrial temperature range before trimming to ±3.3 ppm after a permanent trimming of −426 ppm based on the local evaporation of Al. The trimming rate can be controlled by electric power. A resonator is coarse-trimmed by approximately −807 ppm with an evaporation power of 960 mW for 0.5 h, and fine-trimmed by approximately −815 ppm with an evaporation power of 456 mW for 1 h. Though the Q-factor decreases after trimming, a Q-factor of 304,240 is achieved after the trimming of −1442 ppm.
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O'Neal, Chad B., Ajay P. Malshe, William F. Schmidt, Matthew H. Gordon, and William D. Brown. "Effects of Die Attachment Induced Stress on the Reliability of a Packaged MEMS Device." Journal of Microelectronics and Electronic Packaging 6, no. 3 (July 1, 2009): 164–71. http://dx.doi.org/10.4071/1551-4897-6.3.164.
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A microelectromechanical systems (MEMS) actuator was selected to study the effects of packaging induced stress on device reliability. In this work, MEMS devices were obtained and packaged using cyanate ester, 96.5/3.5 Sn/Ag, and 92.5/5/2.5 Pb/Sn/Ag die attachment materials. The die attachment materials were then cured or reflowed appropriately and cooled to room temperature which induced stress through the coefficient of thermal expansion mismatches between the silicon die and alumina package. In this work, a MEMS microengine developed at Sandia National Laboratories, which is a device that has been well studied, was selected as a test vehicle to understand the effects of various die attachment solders and related processes parameters on the ultimate functionality of the packaged MEMS microengine. Particularly, the operational lifetime of these devices was measured by testing these devices to failure. These lifetimes were then compared with baseline values to determine the effect of stress on these devices. The maximum stress values observed in these studies ranged from 11–23 MPa based on the die attachment material used for cyanate ester to Pb/Sn/Ag solder, respectively. About 50% of the total population tested failed between 105 and 106 cycles, while 25% failed above 106 cycles and the remaining 25% failed below 105 cycles. The reliability results agreed well with previous results. The effect of stress did not seem to adversely affect the device lifetimes for this class of MEMS device, suggesting that these ranges of solders can be safely used to package MEMS devices.
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Duque, Marcos, Edgardo Leon-Salguero, Jordi Sacristán, Jaume Esteve, and Gonzalo Murillo. "Optimization of a Piezoelectric Energy Harvester and Design of a Charge Pump Converter for CMOS-MEMS Monolithic Integration." Sensors 19, no. 8 (April 21, 2019): 1895. http://dx.doi.org/10.3390/s19081895.
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The increasing interest in the Internet of Things (IoT) has led to the rapid development of low-power sensors and wireless networks. However, there are still several barriers that make a global deployment of the IoT difficult. One of these issues is the energy dependence, normally limited by the capacitance of the batteries. A promising solution to provide energy autonomy to the IoT nodes is to harvest residual energy from ambient sources, such as motion, vibrations, light, or heat. Mechanical energy can be converted into electrical energy by using piezoelectric transducers. The piezoelectric generators provide an alternating electrical signal that must be rectified and, therefore, needs a power management circuit to adapt the output to the operating voltage of the IoT devices. The bonding and packaging of the different components constitute a large part of the cost of the manufacturing process of microelectromechanical systems (MEMS) and integrated circuits. This could be reduced by using a monolithic integration of the generator together with the circuitry in a single chip. In this work, we report the optimization, fabrication, and characterization of a vibration-driven piezoelectric MEMS energy harvester, and the design and simulation of a charge-pump converter based on a standard complementary metal–oxide–semiconductor (CMOS) technology. Finally, we propose combining MEMS and CMOS technologies to obtain a fully integrated system that includes the piezoelectric generator device and the charge-pump converter circuit without the need of external components. This solution opens new doors to the development of low-cost autonomous smart dust devices.
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Liew, Li-Anne, Ching-Yi Lin, and Y. C. Lee. "Polymer-Based Hermetic Packaging for Flexible Micro Devices." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2012, DPC (January 1, 2012): 001139–62. http://dx.doi.org/10.4071/2012dpc-tp36.
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In recent years, polymers have been widely adopted as a low-cost, light-weight and high-flexibility alternative to traditional silicon materials for MEMS. However, the majority of polymers do not provide hermetic protection because of their high moisture- and gas permeation rates. Yet, hermetic packaging is critical for many applications such as medical devices [1], RF MEMS [2] and micro heat pipes [3]. In particular, our group has been developing flexible thermal ground planes based on heat pipe technology [3] for advanced electronics cooling applications. Heat pipes require hermetic sealing, while flexibility requires the structural material to be polymer-based. Hermetic packaging methods for MEMS typically include welding, soldering [4], and various epoxies and polymers [1, 2, 5] to bond the parts in a package together. The bond interface is a major potential source of gas and moisture leakage. Although welds and solder joints offer effective hermetic seals, the bond interface is mechanically rigid. On the other hand, flexible bond materials like epoxies typically possess high moisture absorption rate and bonding strength degradation at high temperature [6] while polymers such as BCB [2] or LCP [7] either provide only semi-hermetic sealing or degrade at high temperature. We report a polymer-based hermetic packaging approach using fluorinated ethylene propylene (FEP), which possesses flexibility, high operating temperature compatibility (204°C), chemical resistance, and low water absorption rate. We report results of hermeticity tests in which FEP, solder, and epoxy were used to bond a copper-clad kapton “lid” onto a water-containing copper vessel which is then kept in an oven at 100 °C. The only path for water loss is through the bond interface. We show that the FEP-bonded test vehicles result in negligible water loss comparable to the solder-bonded containers, and far outperforming the epoxy-bonded containers. References: [1] G. Jiang and D. D. Zhou (Ed.), Implantable Neural Prostheses 2, (2010). [2] A Jourdain, P De Moor, K Baert, I DeWolf and H A C Tilmans, J. Micromech. Microeng.,15 (2005) S89–S96. [3] C.J. Oshman, B. Shi, C. Li, R. Yang, Y.C. Lee, G.P. Peterson, and V.M. Bright, J. Microelectromechanical Systems, 20, 2 (2011), 410–417. [4] T. Rude, J. Subramanian, J. Levin, D. Van Heerden, O. Knio, Proc. IMAPS 2005. [5] G. B. Tepolt, M. J. Meschera, J. J. LeBlanca, R. Lutwakb, M. Varghesec, Proc. of SPIE, Vol. 7592, 2010, 759207. [6] E. M. Petrie, Handbook of Adhesives and Sealants, 1st Ed. (McGraw-Hill, 1999), p. 707. [7] C.-D. Ghiu, S. Dalmia, J. Vickers, L. Carastro, W. Czakon, V. Sundaram, G. White, Proc. 1st European Microwave Integrated Circuits Conference, 2006, pp.545–547.
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Herrault, Florian, M. Yajima, M. Chen, C. McGuire, and A. Margomenos. "Silicon-Embedded RF Micro-Inductors for Ultra-Compact RF Subsystems." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2015, DPC (January 1, 2015): 000939–57. http://dx.doi.org/10.4071/2015dpc-tp44.
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Advances in 2.5D and 3D integration technologies are enabling ultra-compact multi-chip modules. In this abstract, we present the design, fabrication, and experimental characterization of RF inductors microfabricated inside deep silicon recesses. Because silicon is often used as a substrate of packaging material for 3D integration and microelectromechanical systems (MEMS), developing microfabrication technologies to embed passive components in the unused volume of the silicon package is a promising approach to realize ultra-compact RF subsystems. Inductors and capacitors are critical in dc-bias circuits for MMICs in order to suppress low-frequency oscillations. Because it is particularly important to have these passive components as close to the MMIC as possible with minimum interconnection parasitics, silicon-embedded passives are an attractive solution. Further, silicon-embedded passives can potentially reduce the overall volume of RF subsystems when compared to modules using discrete passives. Although inductors inside the volume of silicon wafers have previously been reported, they typically operated in the 1–200 MHz frequency range, mostly featuring inductors with wide (50–100 μm) conductors and wide (50–100 μm) interconductor gaps due to fabrication limitations. We first explored process limitations to fabricate structural and electrical features inside 75 to 100-μm-deep silicon cavities. The cavities were etched into the silicon using deep reactive ion etching. Inside these recesses, we demonstrated the fabrication of thin (0.2 μm) and thick (5 μm) gold patterns with 3 μm resolution using lift-off and electroplating processes, respectively. The lift-off process used an image reversal technique, and the plated gold conductors were fabricated through a 6.5-μm-thick photoresist mold. The feature sizes ranged from 3 to 50 μm. For photoresist exposure, an i-line Canon stepper was utilized, and configured specifically to focus at the bottom of the cavities, a key process requirement to achieve high-resolution features. These microfabrication results enabled the design of high-performance RF inductors, which will be discussed in the next section. In addition, we demonstrated the fabrication of 30-μm-deep 3-μm-diameter silicon-etched features inside these cavities, a stepping stone towards achieving high-capacitance-density integrated trench capacitors embedded inside silicon cavities. The silicon-embedded RF inductors were microfabricated on 500-μm-thick high-resistivity (ρ > 20,000 Ω.cm) silicon wafers. First, 75-μm-deep cavities were etched using DRIE. Various two-port coplanar waveguide (CPW) inductor designs were microfabricated. The inductor microfabrication relied on sputtered titanium/gold seed layers, thick AZ4620 photoresist molds, and three 5-μm-thick electroplated gold layers stacked on top of each other to define the inductor conductor and connections. By using a combination of three electroplated layers, high-power-handling low-loss inductors were fabricated. Measurements were performed on a RF probe station, with on-wafer calibration structures. The losses associated with the CPW launchers were de-embedded prior to inductor measurements, and inductor quality factor greater than 40 was measured on various inductors with inductance of approximately 1 nH, and self-resonant frequency at 30 GHz. These results were in agreement with models performed using SONNET simulation package, and are comparable with than that of inductors fabricated on planar silicon wafers.
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Lee, Hyungsuk, and Junghyun Cho. "Parylene-PDMS Bilayer Coatings for Microelectronic and MEMS Packaging." MRS Proceedings 968 (2006). http://dx.doi.org/10.1557/proc-0968-v07-07.
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ABSTRACTCurrent microelectronic devices and microelectromechanical systems (MEMS) require that packaging costs be reduced with more enhanced device performance. In addition, the packaging materials are often exposed to harsh environments, for which their performance is drastically degraded. Importantly, such devices become lighter and smaller, precluding the use of conventional packaging materials and schemes. Given that, surface coatings can provide an alternative solution for some of the aforementioned issues. Polydimethylsiloxane (PDMS) is a good candidate material in many encapsulating applications but its surface must be effectively protected due to its poor surface properties. In this study, the PDMS surface is coated with the parylene C film through a vapor-phase deposition. Proper surface modification of PDMS is then essential to generate desirable interfacial adhesion and performance between the parylene C and the PDMS. Effects of plasma treatment were examined in this study to evaluate their effectiveness on the surface modification of the PDMS. In order to explore mechanical performances of the bilayer coatings, dynamic nanoindentation and feedback-control nanoindentation testings were employed. In addition, extensive surface characterizations are performed with atomic force microscope (AFM) and optical microscope (OM).
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"Activity of the Research Group for Nano- and Microelectromechanical Systems Packaging." Journal of Japan Institute of Electronics Packaging 8, no. 6 (2005): 490–91. http://dx.doi.org/10.5104/jiep.8.490.
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"Interconnection Characteristics of Rivet Packaging for Radio Frequency Microelectromechanical Systems Applications." Sensors and Materials, 2011, 101. http://dx.doi.org/10.18494/sam.2011.667.
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Walwadkar, Satyajit S., Junghyun Cho, P. W. Farrell, and Lawrence E. Felton. "Tailoring of Stress Development in MEMS Packaging Systems." MRS Proceedings 741 (2002). http://dx.doi.org/10.1557/proc-741-j5.22.
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ABSTRACTA better understanding of the origin and evolution of the stresses is a crucial step in improving reliability of packaging systems for microelectromechanical systems (MEMS). Given its importance, we examine the stresses developed in hermetically packaged MEMS inertial sensors. For this purpose, an optical surface profilometer is employed to assess the stresses by measuring the curvature of dummy silicon dies (3.5×3.5 mm2) assembled in different types of packages and die attach adhesives. We also explore a temporal evolution of stresses during thermal exposure of the test packages in an effort to emulate actual packaging processes and device operation conditions. The result shows different levels of stresses generated from various adhesives and package types, and also a stress evolution during packaging processes. The mechanical stress data also show a good agreement with MEMS performance data obtained from actual accelerometers. Therefore, the stress data will not only be useful in better understanding performance of MEMS packages, but the testing protocol can also provide a diagnostic tool for very small packaging systems.