Japanese researchers have no universal definition of MEMS. Some groups think of MEMS as microelectromechanical systems manufactured by integrated circuit processing, mainly in silicon. Other groups think of MEMS as systems that are manufactured by any means as long as microscaled elements are included as part of the system. These systems would most likely not be made of silicon. Japanese universities and industrial research facilities are doing much more extensive work than the United States in nonsilicon MEMS via traditional machining.
In the United States, MEMS has been used to embrace microminiature systems that are constructed with both IC-based fabrication techniques and other mechanical approaches. In most cases, an emphasis has been placed on having the techniques compatible with IC techniques to insure the availability of electronics close by. Most researchers require that MEMS be contained within the same package, while some require that MEMS be contained on a single chip.
To date, the integrated circuit industry has been the technology base that has driven MEMS. This is shown in both the bulk silicon and polysilicon efforts that have been the mainstay of MEMS devices. The MEMS community has made significant advances in the area of deep etching bulk silicon and in surface (sacrificial etching) micromachining with polysilicon. MEMS has driven the silicon community into understanding the mechanical properties of silicon structures in addition to the electrical properties. MEMS has also been a driver behind research into alternative, non-IC-based techniques to obtain microdevices. These techniques include LIGA, laser-assisted CVD, electroplating, electroless plating, and, especially in Japan, conventional machining.