Collective wet etching of a 3D monolithic silicon seismic mass system

Abstract

We present a simple two-step etching process based on anisotropic wet etching of (100) silicon. As one example a system of three seismic masses on one chip has been fabricated. All three masses are symmetrically suspended by four high aspect ratio beams. The highly symmetrical design minimizes mechanical cross-sensitivities. Moreover, the three devices exhibit almost perfect rectangular alignment due to the orientation along the directions of the silicon crystal. Besides experimental results, design rules for the photolithography-masks are presented.