HIGHLY ANISOTROPIC SILICON REACTIVE ION ETCHING FOR NANOFABRICATION USING MIXTURES OF SF6 CHF3 GASES/

A novel highly anisotropic room-temperature process for silicon etchin g, using mixtures of SF6 and CHF3 gases is presented. The etch rate, s electivity, de bias voltage and anisotropy as a function of the reacti ve ion etching conditions (mixture composition, pressure and rf power) are discussed. Excellent anisotropy combined with clean, damage-free surfaces and etching uniformity and reproducibility have been achieved . It was thus possible to fabricate free standing silicon wires with d iameter less than 50 nm and with aspect ratios up to 50:1. Optical emi ssion spectroscopy, ex situ x-ray photoelectron spectroscopy and atomi c force microscopy were employed as plasma gas phase and surface diagn ostics. (C) 1997 American Vacuum Society.