Patent ID: 7122860

Claim:
A trench-gate semiconductor device including: a semiconductor body ( 20 ) defining a trench ( 10 ) having an insulated gate ( 8 ) therein, the semiconductor body comprising a source region ( 2 ) and a drain region ( 4 ) of a first conductivity type which are separated by a channel-accommodating region ( 6 ) adjacent to the gate, the drain region comprising a drain drift region ( 4 a ) and a drain contact region ( 4 b ), with the drain drift region between the channel-accommodating region ( 6 ) and the drain contact region ( 4 b ), and the drain drift region ( 4 a ) doped to a lesser extent than the drain contact region ( 4 b ); and an insulated field plate ( 24 ) in the trench ( 10 ) between the gate ( 8 ) and the drain contact region ( 4 b ), wherein the field plate ( 24 ) is connected in operation to a bias source at a bias potential greater than the gate potential and near to the bulk breakdown voltage of the drain drift region ( 4 a ).