Power module for supporting high current densities

• US 9,673,283 B2
• Filed: 08/17/2012
• Issued: 06/06/2017
• Est. Priority Date: 05/06/2011
• Status: Active Grant

• Current Assignee: Wolfspeed, Inc.
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Henning, Jason Patrick, Ryu, Sei-Hyung, Allen, Scott, Zhang, Qingchun, Agarwal, Anant Kumar, Palmour, John Williams
• Primary Examiner(s): Jahan, Bilkis
• Application Number:
  US13/588,329
• Publication Number:
  US 20130207123A1
• Time in Patent Office: 1,754 Days
• CPC Class Codes: H01L 21/046 using ion implantation
• CPC Class Codes: H01L 21/049 Conductor-insulator-semiconductor electrodes, e.g. MIS contacts
• CPC Class Codes: H01L 25/18 the devices being of types provided for in two or more different subgroups of the same main group of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N
• CPC Class Codes: H01L 27/0629 in combination with diodes, or resistors, or capacitors
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/0696 of cellular field-effect devices, e.g. multicellular DMOS transistors or IGBTs
• CPC Class Codes: H01L 29/1608 Silicon carbide
• CPC Class Codes: H01L 29/66068 the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
• CPC Class Codes: H01L 29/7395 Vertical transistors, e.g. vertical IGBT
• CPC Class Codes: H01L 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• CPC Class Codes: H01L 29/7805 in antiparallel, e.g. freewheel diode
• CPC Class Codes: H01L 29/7806 the other device being a Schottky barrier diode
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H02M 7/003 Constructional details, e.g. physical layout, assembly, wiring or busbar connections
• CPC Class Codes: H02P 7/04 by means of a H-bridge circuit

Abstract

A power module is disclosed that includes a housing with an interior chamber wherein multiple switch modules are mounted within the interior chamber. The switch modules comprise multiple transistors and diodes that are interconnected to facilitate switching power to a load. In one embodiment, at least one of the switch modules supports a current density of at least 10 amperes per cm².

Claims

1. A power module comprising

a housing with an interior chamber;

and

a plurality of switch modules mounted within the interior chamber and comprising a plurality of transistors and a plurality of diodes interconnected to facilitate switching power to a load wherein at least one of the plurality of switch modules supports a current density of at least 10 amperes per cm² and handles a voltage greater than 10 kV.

2. The power module of claim 1 wherein the interior chamber is associated with an interior area and the current density is defined as a ratio of maximum average current that the one of the plurality of switch modules supports to the interior area that is allocated to the one of the plurality of switch modules.

3. The power module of claim 1 wherein the at least one of the plurality of switch modules supports a current density of at least 12 amperes per cm².

4. The power module of claim 1 wherein the at least one of the plurality of switch modules supports a current density of at least 15 amperes per cm².

5. The power module of claim 1 wherein each of the plurality of switch modules forms a portion of a full H-bridge or a half H-bridge.

6. The power module of claim 1 wherein the plurality of transistors are connected in parallel with each other and in anti-parallel with the plurality of diodes.

7. The power module of claim 1 wherein the plurality of transistors and the plurality of diodes are formed from silicon carbide.

8. The power module of claim 1 wherein at least two of the plurality of transistors each comprises:

a drift layer having a first conductivity type;

a well region in the drift layer having a second conductivity type opposite the first conductivity type;

a source region in the well region, the source region having the first conductivity type and defining a channel region in the well region, wherein the source region comprises a lateral source region adjacent the channel region and a plurality of source contact regions extending away from the lateral source region opposite the channel region;

a body contact region having the second conductivity type between at least two of the plurality of source contact regions and in contact with the well region; and

a source ohmic contact that overlaps at least one of the source contact regions and the body contact region, and that does not overlap the lateral source region.

9. The power module of claim 1 wherein at least two of the plurality of transistors each comprises:

a drift layer having a first conductivity type;

a well region having a second conductivity type that is opposite the first conductivity type;

a source region in the well region, the source region having the first conductivity type;

a body contact region having the second conductivity type in contact with the well region; and

a source ohmic contact that overlaps the source region in a source contact area and that overlaps the body contact region in a body contact region area;

wherein a ratio of a minimum dimension n1 of the source contact area to a minimum dimension w1 of the well region is greater than 0.2.

10. The power module of claim 1 wherein at least two of the plurality of transistors each comprises:

a drift layer having a first conductivity type;

a well region having a second conductivity type that is opposite the first conductivity type;

a source region in the well region, the source region having the first conductivity type;

a body contact region having the second conductivity type in contact with the well region; and

a source ohmic contact that overlaps the source region in a source contact area and that overlaps the body contact region in a body contact region area;

wherein a ratio of a minimum dimension p1 of the body contact region area to a minimum dimension w1 of the well region is greater than 0.2.

11. The power module of claim 1 wherein at least two of the plurality of transistors each has a reverse blocking voltage in excess of 1000 volts and has a current density greater than 200 amps per square centimeter at a current greater than 100 A.

12. The power module of claim 1 wherein at least two of the plurality of transistors each has a reverse blocking voltage of 1000 volts or more and has a forward current capability greater than 100 A at a forward voltage of 5 volts or less.

13. The power module of claim 1 wherein at least two of the plurality of transistors have a reverse blocking voltage of 1200 volts or more.

14. The power module of claim 1 wherein at least two of the plurality of transistors are metal-oxide semiconductor field effect transistor devices having a reverse blocking voltage of 1000 volts or more and having a differential on-resistance less than 8 mOhms-cm².

15. The power module of claim 1 wherein at least two of the plurality of transistors each has a blocking voltage less than 1000 V and is configured to pass forward current at a current density greater than 200 amps per square centimeter at a forward voltage drop of 5 V or less.

16. The power module of claim 1 wherein at least two of the plurality of transistors are insulated gate bipolar transistor devices having a forward voltage drop of 5.2 V or less at a current density of 100 A/cm².

17. The power module of claim 1 wherein at least two of the plurality of transistors are metal-oxide semiconductor field effect transistor devices having a drain to source voltage that is less than 4 Volts and a cell pitch of less than 20 μ

m and having a forward current capability greater than 100 A.

18. The power module of claim 17 wherein the cell pitch is less than 10 μ

m.

19. The power module of claim 1 wherein at least two of the plurality of transistors are metal-oxide semiconductor field effect transistor devices having a drain to source voltage that is less than 5 Volts and a cell pitch of less than 10 μ

m and having a forward current capability greater than 80 A.

20. The power module of claim 1 wherein at least two of the plurality of transistors are insulated gate bipolar transistor devices having a blocking voltage of 13 kV or more and a forward current capability of 5 A or greater.

21. The power module of claim 1 wherein the at least one of the plurality of switch modules supports a current density of 15 amperes per cm².

22. The power module of claim 1 wherein the at least one of the plurality of switch modules handles a voltage of 15 kV.

23. A power module comprising

a housing with an interior chamber;

a plurality of switch modules mounted within the interior chamber and comprising a plurality of transistors and a plurality of diodes interconnected to facilitate switching power to a load wherein at least one of the plurality of transistors comprises;

a drift layer having a first conductivity type;

a well region in the drift layer having a second conductivity type opposite the first conductivity type;

a source region in the well region, the source region having the first conductivity type and defining a channel region in the well region, wherein the source region comprises a lateral source region adjacent the channel region and a plurality of source contact regions extending away from the lateral source region opposite the channel region;

a body contact region having the second conductivity type between at least two of the plurality of source contact regions and in contact with the well region, wherein the body contact region comprises a plurality of body contact regions that are interspersed between the plurality of source contact regions; and

a source ohmic contact that overlaps at least one of the source contact regions and the body contact region, and that does not overlap the lateral source region.

24. The power module of claim 23 wherein the plurality of body contact regions are spaced apart from the channel region by the lateral source region.

25. The power module of claim 23, wherein the source ohmic contact overlaps the at least one source contact region in a source contact area and the source ohmic contact overlaps the body contact region in a body contact region area;

wherein a ratio of a minimum dimension n1 of the source contact region area to a minimum dimension w1 of the well region is greater than 0.2.

26. The power module of claim 25 wherein the ratio of the minimum dimension n1 of the source contact region area to the minimum dimension w1 of the well region is between 0.3 and 1.

27. The power module of claim 25 wherein the ratio of the minimum dimension n1 of the source contact region area to the minimum dimension w1 of the well region is greater than 0.5.

28. The power module of claim 23, wherein the source ohmic contact overlaps the source region in a source contact area and the source ohmic contact overlaps the body contact region in a body contact region area;

wherein a ratio of a minimum dimension p1 of the body contact region area to a minimum dimension w1 of the well region is greater than 0.2.

29. The power module of claim 28, wherein the ratio of the minimum dimension p1 of the body contact region area to the minimum dimension w1 of the well region is greater than about 0.3.

30. The power module of claim 28 wherein the ratio of the minimum dimension p1 of the body contact region area to the minimum dimension w1 of the well region is greater than about 0.5.

31. The power module of claim 23 wherein the drift layer comprises a wide bandgap semiconductor material.

32. The power module of claim 31 wherein the drift layer comprises silicon carbide.

33. The power module of claim 31 wherein the drift layer comprises silicon carbide having a 2H, 4H and/or 6H polytype.

34. The power module of claim 31 wherein the drift layer comprises silicon carbide having a 3C and/or 15R polytype.

35. The power module of claim 23 wherein the source region has a sheet resistance and the source ohmic contact has a contact resistance, wherein a ratio of the contact resistance to the sheet resistance is greater than 1.

36. The power module of claim 23 wherein each of the plurality of transistors has a reverse blocking voltage in excess of 1000 volts and a current density greater than 700 amperes per square centimeter.

37. The power module of claim 23 wherein one of the plurality of transistors comprises a field effect transistor.

38. The power module of claim 23 wherein one of the plurality of transistors comprises an insulated gate bipolar transistor.

39. The power module of claim 23 wherein a minimum dimension of a source contact area of each of the plurality of transistors is defined by an area of overlap between the source ohmic contact and the at least one of the source contact regions.