Patent ID: 9570585
Date: 2017-02-14
CPC Classifications: H01L

Claim:
1. A method of forming a transistor device, comprising: providing a drift layer having a first conductivity type; forming a body layer on the drift layer, the body layer having a second conductivity type that is opposite the first conductivity type; forming a source layer on the body layer, the source layer having the first conductivity type; forming a trench in the source layer and the body layer, the trench extending into the drift layer and having an inner sidewall and a floor; sequentially forming a channel layer and a second layer on the inner sidewall and floor of the trench, the channel layer having the first conductivity type and the second layer having the second conductivity type; thermally oxidizing portions of the second layer on the inner sidewall of the trench; removing the oxidized portions of the second layer to leave an un-oxidized portion of the second layer on the floor of the trench; forming a gate insulator on the inner sidewall of the trench over the channel layer and on the floor of the trench over the un-oxidized portion of the second layer; and forming a gate contact on the gate insulator.