Isolation structure and a self-aligned capping layer formed thereon

Abstract

Semiconductor structures and methods are provided. An exemplary method according to the present disclosure includes providing a workpiece including a semiconductor fin protruding from a substrate, a first placeholder gate and a second placeholder gate over channel regions of the semiconductor fin, and a source/drain feature disposed between the channel regions. The method also includes removing a portion of the first placeholder gate and a portion of the substrate directly disposed thereunder to form an isolation trench, forming a dielectric feature in the isolation trench, replacing the second placeholder gate with a metal gate stack, selectively recessing the dielectric feature, forming a first capping layer over the metal gate stack and a second capping layer over the recessed dielectric feature, and forming a source/drain contact over and electrically coupled to the source/drain feature.