Stiction Recovery of Silicon Oxide Cantilevers with Pulse Laser Irradiation for MEMS

Abstract

Recovery of stiction-failed micro-cantilevers with excimer laser irradiation has been attempted on silicon oxide cantilevers. Micro-cantilevers with various lengths and widths have been fabricated from thermo-oxidized silicon with micromachining process. ArF laser (λ=193nm) and KrF laser (λ=248nm) were used for experiments. Laser stiction recovery is possible on micro-cantilevers made of silicon oxide. Recovery yield is dependent on laser fluence and wavelength. ArF laser light, which is well absorbed by silicon oxide, can recover stiction-failed cantilevers more effectively. Adhesion and stiction-recovery do not depend on the width of cantilever. The results are compared with previous data of silicon cantilevers. Using the model that considers the sum of elastic force and thermoelastic force as restoring force, the free standing yield after laser irradiation is calculated. The theoretical results exhibit qualitative agreement with the experimental data of both silicon oxide and silicon cantilevers. This indicates that the thermoelastic force plays an important role in stiction recovery, and its temporal profile may have an influence on the recovery yield.