RF sputtered silicon for MEMS

In this work, we report low temperature (<250 °C) RF sputter deposition of silicon films for MEMS applications. The films were deposited in argon atmosphere in the pressure rage 5–20 mTorr at 100–400 W RF power using a 3 inch diameter silicon target. The effect of deposition parameters (RF power and sputtering pressure) on various properties such as deposition rate, surface morphology and surface roughness of silicon films is investigated. To obtain highly smooth films, the deposition parameters are optimized. The effect of annealing at various temperatures on the crystalline property of the deposited silicon films is observed by x-ray diffraction analysis. The direct wafer bonding processes are carried out between the silicon wafers having deposited silicon films and thermally oxidized wafers. To demonstrate the process for MEMS structure fabrication, amorphous silicon-on-insulator (α-SOI) diaphragms were fabricated.