History of MEMS Technology
MEMS have developed in the past decades, especially in the last fifteen years. In the beginning of 1990s, MEMS emerged with the aid of the development of integrated circuit (IC) fabrication processes, in which sensors, actuators, and control functions are cofabricated in silicon. Since then, remarkable research progresses have been achieved in MEMS under the strong capital promotions from both government and industries. In addition to the commercialization of some less integrated MEMS devices, such as microaccelerometers, inkjet printer head, micromirrors for projection, etc., the concepts and feasibility of more complex MEMS devices have been proposed and demonstrated for the applications in such varied fields as microfluidics, aerospace, biomedical, chemical analysis, wireless communications, data storage, display, optics, etc. Some branches of MEMS, appearing as microoptoelectromechanical systems (MOEMS), micrototal analysis systems (TAS), etc., have attracted a great deal of research interests since their potential applications market. As of the end of 1990s, most of MEMS devices with various sensing or actuating mechanisms were fabricated using silicon bulk micromachining, surface micromachining, and lithography, galvanoforming, moulding (LIGA) processes. Three-dimensional (3D) microfabrication processes incorporating more materials were presented for MEMS recently, when some specific application requirements (e.g., Biomedical devices) and the microactuators with higher output power were called for in MEMS. Micromachining has become the fundamental technology for the fabrication of microelectromechanical devices and, in particular, miniaturized sensors and actuators. Silicon micromachining is the most advanced of the micromachining technologies, and it allows for the fabrication of MEMS that have dimensions in the submillimeter range. It refers to fashioning microscopic mechanical parts out
of silicon substrate or on a silicon substrate, making the structures three dimensional and bringing new principles to the designers. Employing materials such as crystalline silicon, polycrystalline silicon, silicon nitride, etc., a variety of mechanical microstructures including beams, diaphragms, grooves, orifices, springs, gears, suspensions, and a great diversity of other complex mechanical structures have been conceived. Sometimes many microdevices can also be fabricated using semiconductor processing technologies or stereolithography on the polymeric multifunctional structures. There are some very important events happened in the past half century: In 1750s, First electrostatic motors (Benjamin Franklin, Andrew Gordon) In 1958, Silicon strain gauges commercially available December 26, 1959, At California Institute of Technology, Richard Feynman gave a remarkably insightful lecture, There is plenty of room at the bottom. He tried to spur innovative miniature fabrication techniques for micromechannics, but he failed to generate a fundamentally new fabrication technique; In 1967, Invention of surface micromachining (Nathanson, Resonant Gate Transistor); In 1969, Westinghouse creates the Resonant Gate FET based on new microelectronics fabrication techniques; In 1970s, Bulk-etched silicon wafers used as pressure sensors; In 1970, First silicon accelerometer demonstrated (Kulite) ; In 1977, First capacitive pressure sensor (Stanford) ;
In 1980, Petersen, K.E., "Silicon Torsional Scanning Mirror", IBM J. R&D, v24, p631, 1980 ; In 1982, Kurt Petersen published silicon as Structural Material, reference for material properties and etching data for silicon; In 1984, First polysilicon MEMS device (Howe, Muller ) ; In 1980s, early experiments in surface-micromachined polysilicon, first electrostatic comb drive actuatorsmicropositioning disc drive heads; In 1989, Lateral comb drive (Tang, Nguyen, Howe); In late 1980s, micromachining leverages microelectronics industry, widespread experimentation and documentation increased public interest; Early transduction and actuation methods produce simple actuators; Micromachining methods aimed toward improving sensors, thermal and electrical isolation between layers with suspended structures; In early 1990s, Government agencies start large MEMS support programs, AFOSR(Air Force Office of Scientific Research) support basic research in materials and MEMS research, DARPA creates MUMPS foundry services with MCNC in 1993, NIST supports commercial foundries for CMOS and MEMS; In our country, micron/nanometer manufacture technology national key laboratory was founded in 1996; In 1992, Chris Pister (UCLA) creates first micromachined hinge, its features open possibilities for pseudo-3D structures and assembly;
In 1992 ,MCNC starts the Multi User MEMS Process (MUMPS); In 1993, First surface micromachined accelerometer sold (Analog Devices,ADXL50) In 1994 , Bosch process for Deep Reactive Ion Etching is patented ; In 1995, Bio-MEMS comes of age; In 1998, The premiere of Star Wars shown on TIs Digital Mirror Device; In later 1990s, actuation and fabrication methods(such as deep reactive ion etching,laser machining, fluidics, tunneling, deep UV) produce advanced systems . In 2000, MEMS Fiber switches become big business;
