Patent ID: 7785944

Claim:
A method of making a gated semiconductor device, comprising: patterning a single-crystal semiconductor region of a substrate to extend in a lateral direction parallel to a major surface of a substrate and to extend in a direction at least substantially vertical and at least substantially perpendicular to the major surface, the semiconductor region having a first side defined by a first surface of the semiconductor region, the first surface extending in the vertical and lateral directions and a second side opposite the first side, the second side defined by a second surface of the semiconductor region, the second surface being remote from the first surface, and the second surface extending in the vertical and lateral directions; forming a first gate overlying the first side, the first gate overlying a first portion of the first side, the first portion having a first gate length in the lateral direction; and forming a second gate overlying the second side, the second gate overlying a second portion of the second side, the second portion having a second gate length in the lateral direction which is different from the first gate length, the second gate being electrically isolated from the first gate, wherein the first gate and the second gate are formed by: forming a first region consisting essentially of polycrystalline silicon germanium overlying the first side; thereafter forming a second region consisting essentially of polysilicon overlying the second side and insulated from the first region; simultaneously lithographically patterning the first region and the second region using a given opening of a given lithographic mask, and thereafter simultaneously thermally oxidizing the first region and the second region, the first region being oxidized faster than the second region so as to define the first gate length and the second gate length such that the first gate length is shorter than the second gate length.