Commercialization of MEMS and Nano Manufacturing

Shape memory alloys (SMAs) have the potential to be used for a wide variety of microelectromechanical systems (MEMS) applications, providing a unique combination of large deflections and high work output. A major drawback for SMAs in many applications has been the low frequency response, which is typically on the order of 100 Hz or lower, even in microscale SMA actuators. In MEMS applications, the higher surface-to-volume ratios have enabled responses to be improved by an order or magnitude or more. By further shrinking the SMA film/device dimensions, the frequency response may be improved even further. In this paper, we present a new, simplified process for fabricating sputtered, thin film SMA MEMS actuators based on nickel-titanium alloy (NiTi or, aka, NITINOL) that consisted of only one photo step to pattern the actuators using SU8. When heated through its solid–solid phase transition from low-temperature martensite to high-temperature austenite, the NiTi alloy undergoes changes in associated physical properties, such as Young’s modulus, resistivity, and surface roughness, that are critical to controlling MEMS performance. For example, these material property changes allow for the design of active or passive microscale sensors and actuators. In the new process, we are able to fabricate ultrathin films of NiTi with nanoscale thickness, which can be thermally cycled through two stable positions very rapidly, making it an intriguing thermal sensor and actuator material for high frequency applications. Additionally, NiTi can be used as an active thermal switch through resistive (i.e. joule) heating. We demonstrated a greatly improved frequency response of up to 3000 Hz with turn on voltages as low as 0.5 V (corresponding to only 1 mW power consumption) for devices exhibiting microns of cantilever tip deflection over millions of cycles, indicating these new SMA MEMS actuators have potential application for low voltage switching, modulation and tuning.

Vacuum packaging is very important for some micro-electro-mechanical systems (MEMS) devices to perform their basic functions properly and to enhance their reliability by keeping these devices away from harmful external environment. In order to maintain high vacuum in a cavity of MEMS devices, residual gases and leaking gases must be eliminated by embedded getter materials. Micro/Nano film getters absorbing gases inside the tiny cavity of MEMS packaging were introduced in this paper. The fabrication and characterization of micro/nano getters for MEMS applications were also presented. Various kinds of patterned getter films were prepared for different MEMS applications. The activation temperature and sorption capacity of the nonevaporable getter (NEG[1]) films was investigated. The formation of micro/nano films on the inner surface of MEMS devices is totally compatible with Si-based MEMS process and illustrates the applicability of the technique in vacuum maintenance of MEMS devices.

Piezoelectric thin film (PTF) materials present a number of unique properties in different applications, such as high sensitivity for micro electro mechanical systems (MEMS) microphones, and a wide dynamic range, wide displacement and low power consumption for MEMS speakers. Generation and detection of acoustic vibration can be made by piezoelectric devices which use the effects of direct piezoelectricity and inverse piezoelectricity. This paper covers popular PTFs and their applications for acoustic MEMS: lead zirconate titanate (PZT) based thin films and lead free PTFs such as aluminum nitride (AIN), zinc oxide (ZnO) and scandium doped aluminum nitride (ScAIN). The design, vibration mode, and fabrication will determine the frequency range of the acoustic MEMS devices. The performance and properties of PTF are the main parameter for certain MEMS applications are introduced. The main ideas of piezoelectric materials are reviewed and introduced for acoustic MEMS transducers.

MEMS sensors gained over the last two decades an impressive width of applications: (a) ESP: A car is skidding and stabilizes itself without driver intervention (b) Free-fall detection: A laptop falls to the floor and protects the hard drive by parking the read/write drive head automatically before impact. (c) Airbag: An airbag fires before the driver/occupant involved in an impending automotive crash impacts the steering wheel, thereby significantly reducing physical injury risk. MEMS sensors are sensing the environmental conditions and are giving input to electronic control systems. These crucial MEMS sensors are making system reactions to human needs more intelligent, precise, and at much faster reaction rates than humanly possible. Important prerequisites for the success of sensors are their size, functionality, power consumption, and costs. This technical progress in sensor development is realized by micro-machining. The development of these processes was the breakthrough to industrial mass-production for micro-electro-mechanical systems (MEMS). Besides leading-edge micromechanical processes, innovative and robust ASIC designs, thorough simulations of the electrical and mechanical behaviour, a deep understanding of the interactions (mainly over temperature and lifetime) of the package and the mechanical structures are needed. This was achieved over the last 20 years by intense and successful development activities combined with the experience of volume production of billions of sensors. This chapter gives an overview of current MEMS technology, its applications and the market share. The MEMS processes are described, and the challenges of MEMS, compared to standard IC fabrication, are discussed. The evolution of MEMS requirements is presented, and a short survey of MEMS applications is shown. Concepts of newest inertial sensors for ESP-systems are given with an emphasis on the design concepts of the sensing element and the evaluation circuit for achieving excellent noise performance. The chapter concludes with an outlook on arising new MEMS applications such as energy harvester and micro fuel cells.KeywordsPorous SiliconAngular RateInertial SensorAcceleration SensorElectronic Stability ProgramThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Electrodeposited gold is used in movable micro-components of micro-electro-mechanical systems (MEMS) devices to allow further enhancement in the sensitivity and miniaturization of the device [1]. Mechanical strengths of gold are low among materials commonly used as structure materials in electronic devices. Electrodeposition method is advantageous in strengthening metallic materials because of the ability to refine the average grain size to nano-scale, which the mechanical strength increases along with a reduction in the grain size based on the grain boundary strengthening mechanism or the Hall-Petch relationship. Alloying of metallic materials is also an effective strategy to achieve the strengthening according to the solid solution strengthening mechanism.On the other hand, mechanical properties of metallic materials exhibit the sample size effect when dimensions of the specimen are reduced to micro or sub-micro scale. Therefore, mechanical property characterization of materials for MEMS applications should be conducted using specimens having dimensions in micro-scale. Various micro-mechanical testing methods have been developed in our group to characterize micro-specimens, such as micro-compression test [2,3], micro-tensile test [4], and micro-bending test [5]. Among them, micro-bending test is suggested to be the most suitable method to evaluate materials for applications in MEMS when compared with micro-compression and micro-tensile tests since cantilever-like structures are often applied in MEMS components, such as the micro-spring in a MEMS accelerometer.In this study, Au-Cu alloys are prepared by electrodeposition, and micro-mechanical properties of the electrodeposited Au-Cu alloys are characterized by a micro-bending test. Young’s modulus is an important information in design of movable micro-components. A non-destructive Young’s modulus evaluation method, resonance frequency measurement, is conducted using the Au-Cu alloy micro-cantilevers. Also, long-term vibration tests are conducted to reveal structure stability of the Au-Cu alloy micro-cantilevers.The Au-Cu electrolyte used in this work was a commercially available electrolyte provided by MATEX Co. Japan, which contained 17.3 g/L of X3Au(SO3)2 (X = Na, K), 1.26 g/L of CuSO4, and ethylenediaminetetraacetic acid as the additive with pH at 7.5. The electrodeposition was carried out at 50 °C, and the current density was varied from 0.1 to 8 mA/cm2. Specimens used in the micro-bending test were micro-cantilevers fabricated from the Au-Cu alloy films by focused ion beam. Dimensions of the micro-cantilevers fabricated were 10 µm × 10 µm × 50 µm. The micro-bending tests were conducted using a test machine equipped with a spherical diamond indenter at a constant displacement rate of 0.05 µm/s.For the Young’s modulus and long-term structure stability evaluations, the micro-cantilevers were prepared by electrodeposition combined with lithography process. The long-term vibration test was carried out under conditions of the cycle number in a range from 103 to 106, the frequency of 10.0 Hz, and the acceleration of 1.0 G (1 G = 9.8 m/s2). The structure stability was determined by evaluating height profiles of top surface of the micro-cantilevers before and after the vibration test by a 3D optical microscope.The Au-Cu alloy film electrodeposited at 5 mA/cm2 had the finest average grain size among films prepared in this work, which the grain size was 4.76 nm. Bending test of a micro-cantilever prepared from this film shows a high yield stress at 1826 MPa. Gold, copper, and Au-Cu alloys are known to be ductile materials, but brittle fracture was observed during the bending test when the current density used in prepared the film was higher than 5 mA/cm2.From the resonance frequency method, Young’s moduli of the Au-Cu alloy micro-cantilevers were ranged from 68.0 to 79.5 GPa, which were similar to the value of bulk-size specimens and indicated no sample size effect on the Young’s modulus. Regarding the long-term structure stability, after 106 cycles of the vibration test, all the micro-cantilever were still intact, and the height profiles did not change much after the vibration. Results obtained in this study confirmed high mechanical strength and structure stability in the electroplated Au-Cu alloys and demonstrated the advantage in applications as movable components in MEMS devices.[1] D. Yamane et. al. Appl. Phys. Lett. 104 (2014) 074102.[2] C.Y. Chen et. al. Electrochem. Commun. 51 (2016) 51-54.[3] H. Tang et. al. J. Electrochem. Soc. 164 (2017) 244-247[4] Y. Kihara et. al. Mater. Lett. 153 (2015) 36-39[5] K. Asano et. al. ECS J. Solid State Sci. Technol. 8 (2019) P412-P415.

This review article through light on a highly promising & demanding technology, which is set to revolutionize nearly every product category in present era, while discussing the Concept, Design & Development, Fabrication techniques and applications of micro electro-mechanical systems (MEMS) based Devices or systems. Microelectromechanical system discloses outstanding flexibility and adaptability in miniaturization devices followed by their compact dimension, low power consumption, and fine performance. The MEMS devices have numerous and very high potentials of creating a new field of applications for mobile equipment’s with increased flexibility & more reliability. This work deals with research carried out for the development of MEMS based sensors & Actuators and appropriate uses of MEMS. This work carries information’s regarding subsequent commercial and real life applications of MEMS and discusses various recent technological innovations carried out with their advantages & disadvantages. This work also describes the historical development of micro-electromechanical system (MEMS) sensor technology.

The application of micro electromechanical systems (MEMS) technology in several consumer electronics leads to the development of micro/nano power sources with high power and MEMS integration possibility. This work presents the fabrication of a flexible solid-state Li-ion battery (LIB) (~2.1 μm thick) with a design towards electrodes electrical insulation, using conventional, low cost and compatible MEMS fabrication processes. Kapton® substrate provides flexibility to the battery. E-beam deposited 300 nm thick Ge anode was coupled with LiCoO2/LiPON (cathode/solid-state electrolyte) in a battery system. LiCoO2 and LiPON films were deposited by RF-sputtering with a power source of 120 W and 100 W, respectively. LiCoO2 film was annealed at 400 °C after deposition. The new design includes Si3N4 and LiPO thin-films, providing electrode electrical insulation and a battery chemical stability safeguard, respectively. Microstructure and battery performance were investigated by scanning electron microscopy, electric resistivity and electrochemical measurements (open circuit potential, charge/discharge cycles and electrochemical impedance spectroscopy). A rechargeable thin-film and lightweight flexible LIB using MEMS processing compatible materials and techniques is reported.

This research project focuses on production scheduling in MEMS (Microelectromechanical Systems) manufacturing. The MEMS manufacturing process studied in this chapter is based on a commercial SCREAM (single crystal reactive etching and metallization) micro-machining technology. The whole process can be organized into 3 sub-processes, that is, the wafer front-end process, the wafer cap process and the back-end process. Raw wafers are initially released to the two parallel sub-processes, the front-end and wafer cap process, in batches of eighteen wafers. They are processed in these two sub-processes with this batch size concurrently. Each wafer upon completion of all the operations in the front-end process has to be bonded at the bonding machine with a correspondingwafer emerging from thewafer cap process. The bondedwafers are then processed in the back-end process individually instead of in batches. The total processing time for the wafer front-end process is 63.2 hours which is much longer than the total processing time of 14.6 hours for the wafer cap process. Therefore the coordination of the releases of wafers to the front-end process as well as the wafer cap process is an important issue. An ineffective coordination will create longer cycle time and larger WIP (work-in-process). The objective of this study is to develop reasonable scheduling and control policies to reduce cycle time and WIP inventory.

This study presents a comprehensive multi-objective optimization framework specifically designed for micro-electromechanical systems (MEMS). The framework integrates both traditional and adaptive optimization techniques, named Surrogate-Assisted Multi-Objective Optimization (SAMOO) and Adaptive-SAMOO (A-SAMOO), respectively. By addressing key limitations of traditional approaches, such as the consideration of objective constraints and the provision of multiple design options, the proposed framework enhances both flexibility and practical applicability. Results show that adaptive optimization outperforms traditional offline methods by delivering a greater number and higher quality of optimal solutions while requiring fewer finite element method simulations. The adaptive approach showed a significant advantage by attaining high-quality solutions while requiring only 2.8% of the finite element method (FEM) evaluations compared to traditional methods that do not incorporate surrogate models. This performance boost highlights the advantages of online learning in enhancing the accuracy, speed, and diversity of solutions in MEMS optimization. These optimization schemes were tested on multiple MEMS devices with varying physics and complexities, specifically the U-shaped Lorentz force actuator, serpentine Lorentz force actuator, and thermal actuator. The results highlight the robustness and versatility of the proposed methods, particularly in addressing cases involving discrete design variables and strict objective constraints. This comprehensive, step-by-step framework serves as a valuable resource for researchers and practitioners aiming to optimize MEMS designs from the ground up, providing a reliable and effective approach to multi-objective optimization in MEMS applications.

Micromachine technologies based on IC-compatible micromachining have advantages denoted by three M's'.Miniaturization is the most popular but Multiplicity, which means the batch fabrication capability of many complicatedelements, and Microelectronics to control motions or to add different functions such as the optical function are equallyimportant. This paper deals with the application of micromachine technologies to micro optical devices. A basic conceptmaking the best use of the advantages is proposed. Recent examples of optical microelectromechanical systems(MEMS) are reviewed. Keywords: MEMS, micromachine, optics, microactuator, LIGA process, silicon 1. INTRODUCTIONStudies on micromechanical systems(MEMS) have reached such stage that we can built three dimensional microstructures on a silicon substrate and operate micromotors/actuators without particular difficulty[1,2]. Now we mustidentify practical applications of MEMS in order to accelerate the development. Figure 1 shows application opportunities ofmicroactuators and MEMS[3J. Promising applications of MEMS for the near future will be in optics[4-40J, magnetic andoptical heads[1 1, 12], fluidics[13, 14], OA apparatus[15], the handling of cells and macro molecules[16,17}, and microscopywith microprobes{1&.'22] such as STMs (scanning tunneling microscopes) and AFMs (atomic force microscopes). Theseapplications have a common feature in that only very light objects such as mirrors, heads, valves, cells and microprobes aremanipulated and that little physical interaction with the external environment is necessary. One reason is that presentmicroactuators are still primitive and large forces cannot be transmitted to the external world. The other reason is difficulty inpackaging.All the mechanical work can be completed within a microsystem for optical applications. Non contact interfacingbetween the microsystem and the external world is possible. In addition, most of the optical components such as lasers,

Micromachine technologies based on IC-compatible micromachining have advantages denoted by three M's.Miniaturization is the most popular but Multiplicity, which means the batch fabrication capability of many complicatedelements, and Microelectronics to control motions or to add different functions such as the optical function are equallyimportant. This paper deals with the application of micromachine technologies to micro optical devices. A basic conceptmaking the best use of the advantages is proposed. Recent examples of optical microelectromechanical systems(MEMS) are reviewed. Keywords: MEMS, micromachine, optics, niicroactuator, LIGA process, silicon 1. INTRODUCTIONStudies on micromechanical systems(MEMS) have reached such stage that we can built three dimensional microstmctures on a silicon substrate and operate micromotors/actuators without particular difficulty[1 ,2]. Now we mustidentify practical applications of MEMS in order to accelerate the development. Figure 1 shows application opportunities ofmicroactuators and MEMS[3]. Promising applications of MEMS for the near future will be in optics[4lO], magnetic andoptical heads[1 1, 12], fluidics[13, 14], OA apparatus[ 15], the handling of cells and macro molecules[16,17}, and microscopywith microprobes[18'22} such as STMs (scanning tunneling microscopes) and AFMs (atomic force microscopes). Theseapplications have a common feature in that only very light objects such as mirrors, heads, valves, cells and microprobes are

MEMS (micro electro mechanical systems) products have significant growth potential, and are being used in an increasing number of applications. One issue with MEMS devices is manufacture, as current MEMS manufacturing processes not standardized. Design techniques were developed to allow a single MEMS manufacturing flow to meet a wide range of accelerometer specifications. One technique is Metal on proof this is a design method that adds thermally dissimilar materials (such as metal) to the accelerometer proof mass, and isolates the proof mass from resulting thermal stresses. Another technique is variable gap sense capacitance, which uses two different sensing gaps in capacitive transducers. This allows z-axis transducers to provide increased output and improved linearity.

Permanent magnet films for applications in microelectromechanical systems

An approach to maintain vacuum in microelectromechanical systems (MEMS) by integrating the MEMS fabrication process with getter material preparation is presented in this paper. The coating process for a thick film of getter material on silicon and glass wafers, the two commonly used substrates in MEMS fabrication and package, was investigated in detail. The getter material consists of a powder mixture of zirconium, vanadium and iron, which features high sorption capacity to active gases such as H2, O2, N2, CO and H2O vapour. Various kinds of patterned non-evaporable getter (NEG) thick films with thickness from 50 µm to 400 µm were fabricated to investigate the solutions for different MEMS applications. The activation temperature of the thick NEG films was investigated. Fundamental properties of the NEG films were examined, such as the adhesive strength, higher than 119 N cm−2, of the NEG film to Si substrate and the sorption capacity, 4.68 × 106 Pa l m−2, of the coated getter material. The coating of NEG thick film on the inner surface of MEMS pressure sensor illustrates the applicability of the technique in vacuum maintenance of MEMS devices.

Manufacturing and design of micro-electro-mechanical systems (MEMS) often involves consideration of micro-rods or other beam structures that play an important role in MEMS performance. Many MEMS structures are made of either silicon or nickel, however, novel designs may also include more complex multifunctional components made of composite materials. This chapter reviews research in the area of composite micro-rods, which are composed of a coated fiber surrounded by an easily-deformable insulating polymer matrix. Such structural configuration allows for multifunctional design and formability of diverse shapes for micro-components in MEMS applications. Here, the influence of nanostructured fiber-matrix interphases on the global deformation response and local stress distributions in the composite micro-rods subjected to compressive loads is investigated. Finite element modeling of homogeneous and heterogeneous interphases is used to determine parameters that affect the deformation response of a composite micro-rod. Linear elastic and nonlinear elastic matrix material models are used in the simulations. Multi-scale effects in transverse deformation of micro-rods are examined. The ratio of the matrix and interphase Young’s moduli is found to affect the character of global deformation. A transition from barreling to bollarding type of deformation is seen as this ratio changes. This interphase controlled change in the deformation mode constitutes a multi-scale coupling between the micron-size interphase and the global response of a deforming rod. The radial, hoop and shear stress distributions in the interphase region are also seen to be highly dependent on the type of interphase present and its sub- micron property gradients.