The diagnostic micromachined beams on (1 1 1) substrate

Abstract

The undercut process of the micromachined structures on a (1 1 1) oriented silicon wafer is studied in this paper. As observed in the experiment, the undercut of a cantilever on (1 1 1) wafer is along the width of the beam. According to the undercut mechanism, the advantages of fabricating a cantilever on (1 1 1) wafer are three-fold: (1) significantly reduce the etching time and obtain an ideal clamped boundary in the mean time; (2) the thickness as well as the moment of inertia of the cantilever is closer to the ideal case; (3) the flexural rigidity of the cantilever is constant along the beam axis. Consequently, the micromachined cantilever on a (1 1 1) wafer is more appropriate in various applications. For instance, it is more appropriate to fabricate the diagnostic microstructures on the (1 1 1) wafer than on the (1 0 0) wafer in determining the thin film residual stress. © 2001 Elsevier Science B.V. All rights reserved.