Reactive ion etching for submicron structures of refractory metal silicides and polycides

Abstract

Refractory metal silicides and n+ polysilicon/silicides are of particular interest for VLSI gate and interconnection technology. Reactive ion etching experiments have been conducted on sputter-deposited films of MoSi2, CVD n+ polysilicon, and thermal SiO2 using admixtures of SF6 with O2. The influence of partial pressure and total pressure on profile control and etch selectivity has been determined. Highly anisotropic etching of n+ polysilicon and MoSi2 was obtained using a gas mixture of SF6 plus 50% oxygen. Examples of 0.2μ anisotropically etched structures of silicides and n+ polysilicon/silicide stacked films have been realized using electron beam lithography and one step dry etching. Mechanisms of profile control involved in the SF6/O2 system are discussed. In addition, exploratory reactive ion etching studies using SiF4/Cl2 gas mixtures for these materials and TaSi2 have been carried out.