Method of Forming Transistors with Ultra-short Gate Feature

A semiconductor transistor is formed as follows. A gate electrode is formed over but is insulated from a semiconductor body region. A first layer of insulating material is formed over the gate electrode and the semiconductor body region. A second layer of insulating material different from the first layer of insulating material is formed over the first layer of insulating material. Only the second layer of insulating material is etched to form spacers along the side-walls of the gate electrode. Impurities are implanted through the first layer of insulating material to form a source region and a drain region in the body region. A substantial portion of those portions of the first layer of insulting material extending over the source and drain regions is removed.