LDMOS Transistor and Method

In an embodiment, a semiconductor device includes a semiconductor substrate, a LDMOS transistor arranged in a front surface of the semiconductor substrate and a conductive through substrate via. The conductive through substrate via includes a via extending from the front surface to a rear surface of the semiconductor substrate, a conductive plug filling a first portion of the via and a conductive liner layer lining side walls of a second portion of the via and electrically coupled to the conductive plug.