Impact of Si DRIE on Vibratory MEMS Gyroscope Performance

Today angular rate sensors (gyroscopes) for automotive application are fabricated by a silicon surface micromachining process (SMM). One critical performance parameter of these micromachined vibratory gyroscopes is the mechanical coupling between the drive and sense mode due to manufacturing imperfections. Excessive coupling, called quadrature error, leads to large zero rate output (ZRO or Q-Bias). This paper discusses for the first time, the dependence between quadrature error and profile asymmetries in relevant spring structures with respect to non-uniformities of the silicon deep reactive ion etch (Si DRiE) systems used for the SMM processing.