A semiconductor device, and methods of forming the same. In one example, the semiconductor device includes a trench in a substrate having a top surface, and a shield within the trench. The semiconductor device also includes a shield liner between a sidewall of the trench and the shield, and a lateral insulator over the shield contacting the shield liner. The semiconductor device also includes a gate dielectric layer on an exposed sidewall of the trench between the lateral insulator and the top surface. The lateral insulator may have a minimum thickness at least two times thicker than a maximum thickness of the gate dielectric layer.