An MOS device includes a semiconductor layer formed on a substrate, the substrate defining a horizontal plane and a vertical direction normal to the horizontal plane. First and second source/drain regions are formed in the semiconductor layer proximate an upper surface of the semiconductor layer, the first and second source/drain regions being spaced apart relative to one another. A gate is formed proximate the upper surface of the semiconductor layer and disposed at least partially between the first and second source/drain regions. A first dielectric region is formed in the MOS device, the first dielectric region defining a trench extending downward from the upper surface of the semiconductor layer to a first distance into the semiconductor layer, the first dielectric region being formed between the first and second source/drain regions. The MOS device further includes a shielding structure formed primarily in the first dielectric region, at least a portion of the shielding structure being disposed adjacent a bottom wall of the first dielectric region and/or one or more sidewalls of the first dielectric region.