Fabrication of Reactive Ion Etching Systems for Deep Silicon Machining

Abstract

Reactive ion etching (RIE) systems using capacitively coupled plasma (CCP) and inductively coupled plasma (ICP) sources with SF₆ gas have been developed for deep silicon machining with high aspect ratio. The developed RIE systems demonstrated high etch rate (2.3μm/min) and high selectivity (1700) for a sputtered nickel mask in silicon etching. A large capacity turbo molecular pump (TMP) with a small etching chamber was used to realize a low pressure with a high flow rate of etching gas. A circulatory cooling apparatus was used for cooling a silicon wafer. Etch rate showed uniformity within 10% for the area of 50cm². Using the RIE system, we succeeded to etch a 200μm thick silicon wafer vertically through the thickness with an aspect ratio greater than 10. The RIE can be applied to fabricate three-dimensional silicon microstructures.