High voltage thin film transistor with improved on-state characteristics and method for making same

A high voltage, semiconductor-on-insulator electronic device, comprising:

• a substrate;
• a buried oxide layer formed on the substrate, the buried oxide layer having a buried oxide layer thickness;
• a semiconductor layer formed on the buried oxide layer, wherein the semiconductor layer further comprises in lateral sequence a source region, a body region, an offset region, a thin drift region and a drain region;
• a drift region insulating layer formed on the drift region next to the gate oxide layer;
• a further insulating layer formed on the source, body and offset regions next to the drift region insulating layer, which further insulating layer forms a gate oxide layer on at least the source and body regions;
• a gate region formed on the further insulating layer and a portion of the drift region insulating layer;
• the drift region having a lateral length L and the offset region having a lateral length D;
• the length L+D approximately describing the lateral distance between the body and drain regions;
• the drift region having a thickness Tdrift, and the offset region having a thickness Toffset, both thicknesses Tdrift and Toffset substantially perpendicular to said lateral dimension of said semiconductor layer;
• the thickness of the offset region Toffset being thicker than the thickness of the drift region Tdrift;
• and the semiconductor layer having a substantially linear doping profile between the body and drain regions, from a minimum value in the offset region adjacent to the body region, to a maximum value in the thin drift region adjacent to the drain region.