High Voltage Insulated Gate Bipolar Transistors with Minority Carrier Diverter

• US 20100301335A1
• Filed: 09/10/2009
• Published: 12/02/2010
• Est. Priority Date: 06/02/2009
• Status: Active Grant

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Zhang, Qingchun, Ryu, Sei-Hyung
• Granted Patent: US 8,629,509 B2
• Time in Patent Office: Days
• US Class Current: 257/49
• CPC Class Codes: H01L 21/8213 the substrate being a semiconductor, using SiC technology H01L21/8258 takes precedence
• CPC Class Codes: H01L 27/0705 comprising components of the field effect type
• CPC Class Codes: H01L 29/0834 Anode regions of thyristors or gated bipolar-mode devices, e.g. supplementary regions surrounding anode regions
• CPC Class Codes: H01L 29/0839 Cathode regions of thyristors
• CPC Class Codes: H01L 29/1095 Body region, i.e. base region, of DMOS transistors or IGBTs cell layout H01L29/0696
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/165 in different semiconductor regions , e.g. heterojunctions
• CPC Class Codes: H01L 29/7395 Vertical transistors, e.g. vertical IGBT

Abstract

High power insulated gate bipolar junction transistors are provided that include a wide band gap semiconductor bipolar junction transistor (“BJT”) and a wide band gap semiconductor MOSFET that is configured to provide a current to the base of the BJT. These devices further include a minority carrier diversion semiconductor layer on the base of the BJT and coupled to the emitter of the BJT, the minority carrier diversion semiconductor layer having a conductivity type opposite the conductivity type of the base of the BJT and forming a heterojunction with the base of the BJT.

Claims

1. A high power insulated gate bipolar junction transistor (“

IGBT”

), comprising;

a wide band gap semiconductor bipolar junction transistor (“

BJT”

) having a collector, an emitter and a base;

a wide band gap semiconductor MOSFET that is configured to provide a current to the base of the BJT; and

a minority carrier diversion semiconductor layer on the base of the BJT, the minority carrier diversion semiconductor layer having a conductivity type opposite the conductivity type of the base of the BJT and forming a heterojunction with the base of the BJT.

2. The high power IGBT of claim 1, wherein the wide band gap semiconductor BJT comprises a silicon carbide BJT, and wherein the wide band gap semiconductor MOSFET comprises a silicon carbide MOSFET.

3. The high power IGBT of claim 1, wherein the heterojunction has a first built-in potential that is lower than a second built-in potential of a homojunction of the material of the base.

4. The high power IGBT of claim 2, wherein the minority carrier diversion semiconductor layer comprises a doped polysilicon layer.

5. The high power IGBT of claim 4, wherein the IGBT includes:

an n-type injection layer;

a p-type layer on the n-type injection layer;

an n-well in an upper portion of the p-type layer;

a heavily-doped p-type layer in an upper region of the n-well;

a gate dielectric layer on the n-well and the heavily-doped p-type layer; and

a gate electrode on the gate dielectric layer.

6. The high power IGBT of claim 5, wherein the p-type layer on the n-type injection layer comprises a p-type base layer that has a doping concentration that is less than a doping concentration of the heavily-doped p-type layer, and a p-type drift layer on the p-type base layer having a doping concentration that is less than the doping concentration of the p-type base layer.

7. The high power IGBT of claim 6, wherein the doped polysilicon layer is between the gate dielectric layer and the p-type drift layer.

8. The high power IGBT of claim 7, wherein a top surface of the doped polysilicon layer is farther above the n-type injection layer than is a top surface of the n-well.

9. The high power IGBT of claim 7, wherein a first channel region of the n-well that is on a first side of the heavily-doped p-type layer and that is under the gate electrode is doped at a concentration that is substantially the same as a second region of the n-well that is on the opposite side of the heavily-doped p-type layer.

10. The high power IGBT of claim 5, wherein a thickness of a middle portion of the gate insulation layer that is on the doped polysilicon layer is greater than a thickness of an end portion of the gate insulation layer that is one the n-well.

11. The high power IGBT of claim 5, further comprising an electrical connection between the heavily-doped p-type layer and the minority carrier diversion semiconductor layer.

12. A high power p-channel silicon carbide insulated gate bipolar junction transistor (“

IGBT”

), comprising;

an n-type silicon carbide injection layer;

a p-type silicon carbide base layer on the n-type silicon carbide injection layer;

a p-type silicon carbide drift layer on the p-type silicon carbide base layer opposite the n-type silicon carbide injection layer;

a silicon carbide n-well in an upper portion of the p-type silicon carbide drift layer;

an n-type silicon layer on the p-type silicon carbide drift layer opposite the p-type silicon carbide base layer;

a gate insulation layer on the silicon carbide n-well and the n-type silicon layer; and

a gate electrode on the gate insulation layer opposite the silicon carbide n-well and the n-type silicon layer.

13. The high power p-channel silicon carbide IGBT of claim 12, further comprising a p-type silicon carbide emitter layer in an upper surface of the silicon carbide n-well, wherein the n-type silicon layer is electrically connected to the p-type silicon carbide emitter layer.

14. The high power p-channel silicon carbide IGBT of claim 13, wherein the silicon layer comprises a minority carrier diverter that forms a heterojunction with the p-type silicon carbide drift layer.

15. The high power p-channel silicon carbide IGBT of claim 14, wherein a top surface of the silicon layer is farther above the n-type silicon carbide substrate than is a top surface of the silicon carbide n-well.

16. A high power silicon carbide insulated gate bipolar junction transistor (“

IGBT”

), comprising;

a silicon carbide bipolar junction transistor (“

BJT”

) having a collector region, an emitter region and a base region;

a silicon carbide MOSFET having a source region, a drain region and a gate electrode; and

a doped semiconductor layer within a layer structure of the silicon carbide IGBT that forms a p-n heterojunction with a silicon carbide layer of the silicon carbide IGBT.

17. The high power silicon carbide IGBT of claim 16, wherein the doped semiconductor layer comprises a doped silicon layer.

18. The high power silicon carbide IGBT of claim 17, wherein the doped silicon layer comprises a doped polysilicon minority carrier diverter.

19. The high power silicon carbide IGBT of claim 18, wherein a top surface of the doped polysilicon layer is farther above an n-type substrate of the IGBT than is a top surface of the collector region of the BJT.