METHODS OF FORMING A METAL SILICIDE LAYER FOR SEMICONDUCTOR DEVICES

Methods of forming a metal silicide layer are provided that include exposing polysilicon through just dry etching (JDE) and recessesing an oxide layer through chemical dry etching (CDE). In particular, dry etching is primarily performed to an extent to expose the polysilicon. Then, CDE is secondarily performed to expose the polysilicon. The CDE process includes selecting an etchant source among combinations of NF3 and NH3, HF and NH3, and N2, H2, and NF3, dissociating the etchant source, forming an etchant of NH4F and NH4F.HF through the dissociation, producing solid by-products of (NH4)2SiF6 through the reaction between the etchant and an oxide at a low temperature, and annealing the by-products at a high temperature such that the by-products are sublimated into gas-phase SiF4, NH3, and HF.