A semiconductor device is provided. The semiconductor device includes a substrate, first and second wells of a first conductivity type, a third well of a second conductivity type, different from the first conductivity type, a first doped region of the first conductivity type in the second well, a metal-oxide-semiconductor device, and a feature. The metal-oxide-semiconductor device is at least partially disposed within the substrate and includes a gate structure disposed above the first well. The gate structure, the first doped region, or the combination thereof is configured to be floated. The feature is disposed adjacent to the metal-oxide-semiconductor device. The feature extends into the substrate with a first depth and a portion of the metal-oxide-semiconductor device extends into the substrate with a second depth smaller than the first depth.