MEMS Opportunities in Accelerometers and Gyros and the Microtribology Problems Limiting Commercialization

Abstract

This paper discusses the application of surface micromachined technology to opportunities in accelerometers and gyros. Consideration is from the design and development of two micron polysilicon mechanical structures (LPCVD) that are integrated with a BIMOS process on a single IC chip. The limitations of commercialization due to high static friction (stiction) is discussed especially with consideration of the conflicting manufacturing processes required to build an integrated MEMS device and minimize high static friction. The product trends are to structures that have larger compliance and therefore require “nonsticky surfaces”. This is further complicated by device robustness expectations and very low ppm failure rates in the applications. The gyro places additional challenges on the technology with the need for high vibrational Q’s achieved by vacuum environments. This paper concludes with identification of critical research issues and how the MEMS industry can be enhanced with a better understanding of Microtribology.