Process for producing silicon carbide crystals having increased minority carrier lifetimes

• US 8,618,553 B2
• Filed: 08/30/2010
• Issued: 12/31/2013
• Est. Priority Date: 12/22/2004
• Status: Active Grant

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Carter, Calvin H. Jr., Jenny, Jason R., Malta, David P., Hobgood, Hudson M., Tsvetkov, Valeri F., Das, Mrinal K.
• Primary Examiner(s): REAMES, MATTHEW L
• Application Number:
  US12/871,095
• Publication Number:
  US 20100320477A1
• Time in Patent Office: 1,219 Days
• Field of Search: 257/777, 257/656, 257/E29.104
• US Class Current: 257/77
• CPC Class Codes: C30B 11/003 Heating or cooling of the melt or the crystallised material
• CPC Class Codes: C30B 29/36 Carbides
• CPC Class Codes: C30B 33/02 Heat treatment C30B33/04, C30B33/06 take precedence

Abstract

A process is described for producing silicon carbide crystals having increased minority carrier lifetimes. The process includes the steps of heating and slowly cooling a silicon carbide crystal having a first concentration of minority carrier recombination centers such that the resultant concentration of minority carrier recombination centers is lower than the first concentration.

Claims

1. A silicon carbide single crystal wafer having a minority carrier lifetime of at least 20 microseconds.

2. The silicon carbide single crystal wafer of claim 1 further comprising an epitaxial layer.

3. The silicon carbide single crystal of claim 1, wherein said wafer has a minority carrier lifetime of at least about 30 microseconds.

4. The silicon carbide single crystal wafer of claim 3 further comprising an epitaxial layer.

5. A semiconductor device comprising:

a silicon carbide single crystal substrate having a minority carrier lifetime of at least 20 microseconds; and

at least one epitaxial layer.

6. The semiconductor device of claim 5 wherein said device is a power device.

7. The semiconductor device of claim 6 wherein said device is selected from the group consisting of a pn diode, a PiN diode, a thyristor and an IGBT.

8. The semiconductor device of claim 5, wherein said substrate has a minority carrier lifetime of at least about 30 microseconds.

9. The semiconductor device of claim 8 wherein said device is a power device.

10. The semiconductor device of claim 9 wherein said device is selected from the group consisting of a pn diode, a PiN diode, a thyristor and an IGBT.

11. A diode comprising:

a p type layer;

an n type layer; and

a silicon carbide intrinsic layer sandwiched in between the p type layer and the n type layer wherein the minority carrier lifetime of the intrinsic layer is at least 20 microseconds.

12. The silicon carbide single crystal of claim 11, wherein said intrinsic layer has a minority carrier lifetime of at least about 30 microseconds.