Patent ID: 9711631
Date: 2017-07-18
CPC Classifications: H01L

Claim:
1. A method for forming an IGBT device, comprising: providing a substrate including a bottom semiconductor layer of a first conductivity type and an upper semiconductor layer of a second conductivity opposite the first conductivity type located above the bottom semiconductor layer; forming at least one first trench for a first gate and a second trench for a second gate in the substrate, wherein each of the at least one first trench and the second trench is provided with a gate insulator and filled with polysilicon and wherein the second trench extends vertically to a depth deeper than the at least one first trench; forming at least one stacked layer over the upper semiconductor layer, wherein the at least one stacked layer includes alternating layers of a floating body layer of the second conductivity type provided on top of a floating body layer of the first conductivity type; and forming a body region of the first conductivity type over the at least one stacked layer, wherein the at least one stacked layer is located at a depth between a bottom of the gate trench and a bottom of the at least one first trench, wherein a bottom of the second gate reaches into the upper semiconductor layer.