Patent ID: 6808952
Filing Date: 2004-10-26
Classification: B81C

Abstract:
A process for fabricating a microelectromechanical (MEM) structure on a device side of a substrate, comprising steps for:(a) partially building up the MEM structure by depositing and patterning a plurality of layers of polysilicon on the device side of the substrate with each adjacent pair of polysilicon layers being separated by a layer of a sacrificial material, and with the layers of polysilicon and the sacrificial material having an accumulated stress of a sufficient magnitude after a step for annealing the substrate to produce a bowing of the substrate characterized by a radius of curvature of the substrate which is less than a critical value; (b) depositing a stress-compensation layer on a backside of the substrate opposite the device side to reduce the bowing of the substrate, with the radius of curvature of the substrate being increased to more than the critical value; and (c) depositing and patterning at least one additional layer of polysilicon on the device side of the substrate to complete building up the MEM structure.