Procesos de grabado seco de silicio monocristalino con alta velocidad de grabado y anisotropía para su aplicación en la fabricación de MEMS

Abstract

The results of dry etching of monocrystalline silicon for micro-electo-mechanical systems (MEMS) applications by using a RIE/ICP system are shown. The contribution of the physical and chemical components over the etch rate and etch profile was analized by the variation of the pressure, ion bombardment, flux, type and gas mixture; and over the distance of the dense plasma. The main reactive gas used was SF$_{6}$ in mixture with Ar, O$_{2}$, or CF$_{4.}$ Masking materials of photoresist, silicon dioxide, and aluminum were used. Anisotropic etch rates up to 4 $\mu $m/min with SiO$_{2}$ as masking material, and isotropric etch rates up to 13 $\mu $m/min with Al as masking material were obtained, both in SF$_{6}$/O$_{2}$ plasma. Vertical etch profiles were observed when the self-bias voltage is the highest, and the masking material presented a strong effect over the obtained results.