Etch profile control of via opening

Abstract

A method comprises forming a gate dielectric cap over a gate structure; forming source/drain contacts over the semiconductor substrate, with the gate dielectric cap laterally between the source/drain contacts; depositing an etch-resistant layer over the gate dielectric cap; depositing a contact etch stop layer over the etch-resistant layer and an interlayer dielectric (ILD) layer over the contact etch stop layer; performing a first etching process to form a via opening extending through the ILD layer and terminating prior to reaching the etch-resistant layer; performing a second etching process to deepen the via opening such that one of the source/drain contacts is exposed, wherein the second etching process etches the etch-resistant layer at a slower etch rate than etching the contact etch stop layer; and depositing a metal material to fill the deepened via opening.