Method and structure for cost effective enhanced self-aligned contacts

Abstract

Various semiconductor fabrication methods and structures are disclosed for cost effectively fabricating a self-aligned contact. A source-drain active region is on a substrate and horizontally extends to sidewall spacers of two adjacent gate stacks on the substrate. A conductive material layer including Titanium is formed by selective deposition on the source-drain active area. An interlevel dielectric (ILD) layer is deposited over the source-drain active area and the two gate stacks. Vertical directional etching in the ILD layer forms a vertical trench contacting the conductive material layer. Selective wet etching in the vertical trench selectively etches the conductive material layer and forms a void therein. Deposition of a second conductive material in the vertical trench fills the vertical trench, including the void, and the second conductive material contacts the top surface of the source-drain active area to form a source-drain self-aligned contact.