In an embodiment, this invention discloses a top-drain lateral diffusion metal oxide field effect semiconductor (TD-LDMOS) device supported on a semiconductor substrate. The TD-LDMOS includes a source electrode disposed on a bottom surface of the semiconductor substrate. The TD-LDMOS further includes a source region and a drain region disposed on two opposite sides of a planar gate disposed on a top surface of the semiconductor substrate wherein the source region is encompassed in a body region constituting a drift region as a lateral current channel between the source region and drain region under the planar gate. The TD-LDMOS further includes at least a trench filled with a conductive material and extending vertically from the body region near the top surface downwardly to electrically contact the source electrode disposed on the bottom surface of the semiconductor substrate.