Methods of fabricating silicon carbide crystals

• US 7,135,072 B2
• Filed: 01/13/2004
• Issued: 11/14/2006
• Est. Priority Date: 05/21/2001
• Status: Expired due to Term

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Mueller, Stephan
• Primary Examiner(s): Gupta, Yogendra N.
• Assistant Examiner(s): Song, Matthew J
• Application Number:
  US10/756,542
• Publication Number:
  US 20040144299A1
• Time in Patent Office: 1,036 Days
• Field of Search: 117/84, 117/88, 117/94, 117/97, 117/911, 117/951
• US Class Current: 117/84
• CPC Class Codes: C30B 23/00 Single-crystal growth by condensing evaporated or sublimed materials
• CPC Class Codes: C30B 23/025 characterised by the substrate
• CPC Class Codes: C30B 29/36 Carbides
• CPC Class Codes: Y10S 117/911 Seed or rod holders

Abstract

Methods for producing silicon carbide crystals, seed crystal holders and seed crystal for use in producing silicon carbide crystals and silicon carbide crystals are provided. Silicon carbide crystals are produced by forcing nucleation sites of a silicon carbide seed crystal to a predefined pattern and growing silicon carbide utilizing physical vapor transport (PVT) so as to provide selective preferential growth of silicon carbide corresponding to the predefined pattern. Seed holders and seed crystals are provided for such methods. Silicon carbide crystals having regions of higher and lower defect density are also provided.

Claims

1. A method of producing a silicon carbide boule having a substantially single polytype, the method comprising:

forcing nucleation sites on a surface of a silicon carbide seed crystal having the substantially single polytype to a predefined pattern; and

growing the silicon carbide boule utilizing physical vapor transport (PVT) so as to provide selective preferential growth of silicon carbide on the silicon carbide seed crystal corresponding to the predefined pattern;

wherein forcing nucleation sites comprises forming a pattern of material other than silicon carbide on a surface of the silicon carbide seed crystal thereby selectively exposing portions of the seed crystal to define the nucleation sites in the selectively exposed portions of the seed crystal;

wherein the pattern of material other than silicon carbide provides a pattern of regions having a reduced sticking coefficient than that of the exposed portions of the seed crystal; and

wherein the silicon carbide boule grows laterally above the material other than silicon carbide.

2. The method of claim 1, wherein the pattern comprises stripes on the seed crystal.

3. The method of claim 1, wherein the pattern comprises a plurality of posts on the seed crystal.

4. The method of claim 1, wherein the pattern comprises a layer of material having a plurality of openings therein so as to expose portions of the seed crystal.

5. The method of claim 4, wherein the openings are substantially circular.

6. The method of claim 1, wherein the material other than silicon carbide comprises graphite.