Tungsten silicide/ tungsten polycide anisotropic dry etch process

摘要

A process for anisotropically etching a tungsten silicide or tungsten polycide structure. If the silicide/polycide film has an overlying oxide layer, the insulating layer is removed by a gas mixture composed of CHF3 and C2F6. The WSix silicide layer is then etched in a reactive ion etch using a gas mixture formed from Cl2 and C2F6, with sufficient O2 added to control polymer formation and prevent undercutting of the silicide. The polysilicon layer is then etched using a gas mixture formed from Cl2 and C2F6. The result is a highly anisotropic etch process which preserves the critical dimension of the etched structures. The etch parameters may be varied to produce a tapered sidewall profile for use in the formation of butted contacts without the need for a contact mask.