Various embodiments of the present disclosure are directed towards a semiconductor device including a gate structure. The semiconductor device further includes a pair of spacer segments on a semiconductor substrate. A high-κ gate dielectric structure overlies the semiconductor substrate. The high-κ gate dielectric structure is laterally between and borders the spacer segments. The gate structure overlies the high-k gate dielectric structure and has a top surface about even with a top surface of the spacer segments. The gate structure includes a metal structure and a gate body layer. The gate body layer has a top surface that is vertically offset from a top surface of the metal structure and further has a lower portion cupped by the metal structure.