Design Tools and Issues of Silicon Micromachined ( Mems ) Devices

This paper describes the design and design issues associated with silicon surface micromachined device design. Some of the tools described are adaptations of macro analysis tools. Design issues in the microdomain differ greatly from design issues encountered in the macrodomain. Microdomain forces caused by electrostatic attraction, surface tension, Van der Walls forces, and others can be more significant than inertia, friction, or gravity. Design and analysis tools developed for macrodomain devices are inadequate in most cases for microdomain devices. Microdomain specific design and analysis tools are being developed, but are still immature and lack adequate functionality. The fundamental design process for surface micromachined devices is significantly different than the design process employed in the design of macro sized devices. In this paper, MEMS design will be discussed as well as the tools used to develop the designs and the issues relating fabrication processes to design. Design and analysis of MEMS devices is directly coupled to the silicon micromachining processes used to fabricate the devices. These processes introduce significant design limitations and must be well understood before designs can be successfully developed. In addition, some silicon micromachining fabrication processes facilitate the integration of silicon micromachines with microelectronics onchip. For devices requiring on-chip electronics, the fabrication processes introduce additional design constraints that must be taken into account during design and analysis.