Two step mask process to eliminate gate end cap shortening

Abstract

Metal oxide semiconductor devices are formed having gates with minimum endcap width and no source/drain leakage. A pair of source/drain regions is formed in a substrate, and a gate oxide is formed on the substrate. A layer of a conductive material, such as polysilicon, is formed on the gate oxide layer, masked and etched to form an extended-width gate having endcaps of a greater width than the endcap design rules. A second mask is formed to cover the extended-width gate up to the desired width of the endcaps (i.e., the design width) and to expose the portions of the extended-width gate beyond the endcap design width. The exposed portions of the extended-width gate are then etched, resulting in a completed gate having endcaps of the design width. Since the endcaps are initially formed to a greater width than the design width, any pullback that occurs during printing of the mask or etching of the gate does not cause the gate to be insufficiently wide to avoid source/drain leakage. Since the excess endcap material is removed, adjacent features and/or devices can be densely spaced on the substrate.