Various embodiments of the present application are directed to an IC, and associated forming methods. In some embodiments, the IC has a plurality of logic devices disposed on a logic region of a substrate, including a first logic device configured to operate at a first voltage and comprising a first logic gate electrode separated from the substrate by a first logic gate dielectric. The first logic gate dielectric is disposed along sidewall and bottom surfaces of a logic device trench of the substrate, and the first logic gate electrode is disposed conformally along the first logic gate dielectric within the logic device trench. A hard mask layer is disposed on the first logic gate electrode within the logic device trench.