Insulated gate bipolar transistors including current suppressing layers
AssigneeCree, Inc.
InventorQingchun Zhang
Life of this patent
Estimating the term…
Abstract
An insulated gate bipolar transistor (IGBT) includes a first conductivity type substrate and a second conductivity type drift layer on the substrate. The second conductivity type is opposite the first conductivity type. The IGBT further includes a current suppressing layer on the drift layer. The current suppressing layer has the second conductivity type and has a doping concentration that is larger than a doping concentration of the drift layer. A first conductivity type well region is in the current suppressing layer. The well region has a junction depth that is less than a thickness of the current suppressing layer, and the current suppressing layer extends laterally beneath the well region. A second conductivity type emitter region is in the well region.
Claims20
An insulated gate bipolar transistor, comprising:
- a substrate having a first conductivity type;
- a drift layer on the substrate and having a second conductivity type opposite the first conductivity type;
- a current suppressing layer on the drift layer, the current suppressing layer having the second conductivity type and having a doping concentration that is larger than a doping concentration of the drift layer;
- a well region in the current suppressing layer and having the first conductivity type, wherein the well region has a junction depth that is less than a thickness, of the current suppressing layer, and wherein the current suppressing layer extends laterally beneath the well region;
- and
- an emitter region in the well region and having the second conductivity type.
A method of forming an insulated gate bipolar transistor, comprising:
- providing a substrate having a first conductivity type;
- forming a drift layer on the substrate, wherein the drift layer has a second conductivity type opposite the first conductivity type;
- forming a current suppressing layer on the drift layer, wherein the current suppressing layer has the second conductivity type and has a doping concentration that is larger than a doping concentration of the drift layer;
- forming a well region in the current suppressing layer, wherein the well region has the first conductivity type;
- and
- forming an emitter region in the well region, wherein the emitter region has the second conductivity type.
An insulated gate bipolar transistor, comprising:
- an n-type silicon carbide substrate;
- a p-type silicon carbide drift layer on the n-type silicon carbide substrate;
- a p-type epitaxial silicon carbide current suppressing layer on the p-type silicon carbide drift layer, the epitaxial current suppressing layer having a doping concentration that is larger than a doping concentration of the p-type silicon carbide drift layer;
- an n+ well region in the epitaxial current suppressing layer, wherein the n+ well region has a junction depth that is less than a thickness of the epitaxial current suppressing layer;
- and
- a p+ emitter region in the n+ well region.
Dependencies are inferred from the claim text.