CONCAVE CORNER COMPENSATION BETWEEN VERTICAL (010)-(001)PLANES ANISOTROPICALLY ETCHED IN SI(100)

This work presents a concave corner-compensation technique, to reduce substantially the residual {111} flanges between two vertical (010)-(0 01) planes, underetched on a (100) silicon wafer. A carefully planned set of rectangles is used, oriented parallel or perpendicular to the w afer flat, at 45 degrees to the desired underetched vertical (010) and (001) planes. The set of rectangles is designed based on several prin ciples, and the behavior Juring etching is graphically and numerically simulated. The predicted behavior is confirmed by experiment. The tec hnique is used to fabricate a square-cross-section beam for an angular -rate-measurement sensor. Natural frequencies of vibrations in the hor izontal and vertical directions are simulated and compared to measurem ent. (C) 1998 Elsevier Science S.A. All rights reserved.