Fabrication of a symmetrical accelerometer structure

This paper reports a capacitive accelerometer structure with highly symmetrical eight springs and a mass. The accelerometer structure is formed simply by multilayer oxidation and wet etching (MOWE) technique, avoiding the generally adopted deep-groove photolithography when fabricating the thin spring. TMAH+Triton is selected as the etchant because it not only provides the minimum undercutting at the mass corner, thus saving much space of the compensation parts, but also allows the good control of spring thickness at low etch rate. The advanced accelerometer performance could be expected due to the symmetrical structure, the large proof mass, controllable spring shape, the narrow uniform capacitive gap, and the IC-compatible process.