In some embodiments, a semiconductor device is provided. The semiconductor device includes a source region and a drain region arranged in a semiconductor substrate, where the source region is laterally separated from the drain region. A gate stack is arranged over the semiconductor substrate and between the source region and the drain region. A cap layer is arranged over the gate stack, where a bottom surface of the cap layer contacts a top surface of the gate stack. Sidewall spacers are arranged along sides of the gate stack and the cap layer. A resist protective oxide (RPO) layer is disposed over the cap layer, where the RPO layer extends along sides of the sidewalls spacers to the semiconductor substrate. A contact etch stop layer is arranged over the RPO layer, the source region, and the drain region.