Abstract: Embodiments of the invention provide approaches for replacement metal gate (RMG) diffusion break formation. Specifically, a diffusion break is created after source/drain (S/D) formation, thereby allowing facet free and high quality S/D formation. A dummy gate body is removed selective to a sidewall section of a capping layer and a GOx layer formed over a substrate, and the opening is then extended through the GOx layer and into the substrate by etching the dummy gate body selective to the sidewall section of the capping layer. Retaining the capping layer during the dummy gate body etch enables the diffusion break to be self-aligned to the gate and eliminates device variability due to S/D volume variations. Processing then continues with RMG poly open chemical mechanical planarization (POC) and poly open planarization (POP).