Method of fabricating self-aligned contact window which includes forming

Abstract

A method of fabricating a self-aligned contact window is described. A gate oxide layer, a conductive layer, a first oxide layer and an undoped polysilicon layer are successively formed on a substrate. These layers above are patterned to form a gate structure. A water clean step is performed, producing a recess in the first oxide layer. A second oxide layer is thermally formed on the surface of the gate structure. An undoped polysilicon spacer is formed on the sidewall of the gate structure and a portion of the undoped polysilicon spacer extends into the recess of the first oxide layer. A dielectric layer is formed over the substrate and using the undoped polysilicon spacer as an etching stop, a self-aligned contact window is formed to expose the source/drain region.