A lateral diffusion metal oxide semiconductor (LDMOS) comprises a semiconductor substrate having an STI structure in a top surface of the substrate, a drift region below the STI structure, and a source region and a drain region on opposite sides of the STI structure. A gate conductor is on the substrate over a gap between the STI structure and the source region and partially overlaps the drift region. A conformal dielectric layer is on the top surface and forms a mesa above the gate conductor. The conformal dielectric layer has a conformal etch-stop layer embedded therein. Contact studs extend through the dielectric layer and the etch-stop layer, and are connected to the source region, drain region, and gate conductor. A source electrode contacts the source contact stud, a gate electrode contacts the gate contact stud, and a drain electrode contacts the drain contact stud. A drift electrode is over the drift region.