Eutectic Trimming of Polysilicon Micro Hemispherical Resonating Gyroscope

An algorithm based on localized stiffness modification for mode trimming of poly-silicon micro hemispherical resonating gyroscope (mu HRG) is presented. This work introduces a new and systematic trimming algorithm to compensate for frequency mismatch and mode misalignment based on laser-induced silicon-metal eutectic formation. The stiffness changes are applied to the vicinity of the supporting post at the base of a hemispherical resonator, a region which has not been previously studied for this purpose. Our study shows the four-nodal point elliptical wineglass modes are highly sensitive to strain modifications around the post. An algorithm is developed and proven effective through FEM simulations in COMSOL, where a significant reduction (>10X) of the frequency split of the wineglass modes in an imperfect mu HRG has been achieved.