All-tungsten scheme for source/drain contact, source/drain via, and gate via

Abstract

The present disclosure provides a method for semiconductor fabrication. The method includes receiving a workpiece having gate structures over channel regions on a substrate and source/drain (S/D) features adjacent to the channel regions. The method then forms tungsten S/D contacts over the S/D features in a first ILD layer by a first selective bottom-up metal growth process. The method forms tungsten S/D vias over the tungsten S/D contacts in a second ILD layer by a second selective bottom-up metal growth process. And after forming the tungsten S/D vias, the method forms tungsten gate vias over the gate structures in the first and the second ILD layer. The forming of the tungsten gate vias includes forming a tungsten seed layer by physical vapor deposition (PVD), and depositing tungsten directly on horizontal and sidewall surfaces of the tungsten seed layer by chemical vapor deposition (CVD).