Reactive ion etching of Ta–silicide/polysilicon double layers for the fabrication of integrated circuits

Polysilicides currently find great interest as low resistivity gate and interconnect materials for integrated MOS circuits. We report on detailed investigations of the dry etching characteristics of Ta–silicide/n+-poly-Si double layers in fluorine and chlorine containing gases. A batch-type parallel plate reactor operated in RIE mode is used. We find a sensitive dependence of the etching results on various process parameters, such as gas mixtures, pressure, and rf power. Possible mechanisms for these findings are discussed. Anisotropic etching of the double layer has been achieved using a two stage process. In addition, we analyze the influence of the layer preparation technique on etching profiles.