Issues associated with the design, fabrication and testing of a crystalline silicon ring gyroscope with electromagnetic actuation and sensing

The design of a single-crystal silicon ring with electromagnetic actuation and sensing, for the purpose of producing a gyroscope, is presented which takes into account the anisotropic nature of silicon. Ring structures are fabricated using a reactive ion etching process which is compatible with CMOS fabrication technology. Three methods of reducing electrical coupling between the drive and the sense are considered. The modes of vibration of the ring are measured as a function of frequency and drive amplitude and interpreted in terms of the modes of an ideal structure. Unwanted asymmetry in the ring structure resulting from the fabrication process is responsible for both a frequency mismatch and a large mechanical coupling between the principal modes of the ring and this limits the response as a gyroscope. Improvements to the fabrication of the ring are identified.