Method of crystal growth and resulted structures

• US 6,579,359 B1
• Filed: 06/02/2000
• Issued: 06/17/2003
• Est. Priority Date: 06/02/1999
• Status: Active Grant

• Current Assignee: Ostendo Technologies Inc.
• Original Assignee: Technologies And Devices International Inc.
• Inventors: Tsvetkov, Denis, Syrkin, Alexander, Lebedev, Alexander, Mynbaev, Karim, Saddow, Stephen, Mynbaeva, Marina, Savkina, Nataliya, Dmitriev, Vladimir
• Primary Examiner(s): KUNEMUND, ROBERT M
• Application Number:
  US09/585,331
• Time in Patent Office: 1,110 Days
• Field of Search: 117/94, 117/95, 117/107, 117/108, 117/952
• US Class Current: 117/94
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 29/36 Carbides
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 33/00 After-treatment of single crystals or homogeneous polycrystalline material with defined structure C30B31/00 takes precedence
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02513 Microstructure
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041

Abstract

A method is disclosed for fabricating monocrystal material with the bandgap width exceeding 1.8 eV. The method comprises the steps of processing a monocrystal semiconductor wafer to develop a porous layer through electrolytic treatment of the wafer at direct current under UV-illumination, and epitaxially growing a monocrystal layer on said porous layer. Growth on porous layer produces semiconductor material with reduced stress and better characteristics than with the same material grown on non-porous layers and substrates. Also, semiconductor device structure comprising at least one layer of porous group III material is included.

Claims

1. A method of fabricating monocrystal material comprising:

a first step of processing a monocrystal wafer to develop a porous monocrystal layer,

a second step of processing said monocrystal wafer with developed pores to transform at least some of the pores into voids, and

epitaxially growing monocrystal material on said porous monocrystal layer.

2. A method of claim 1, where said monocrystal material being made of material having bandgap width exceeding 1.8 eV.

3. The method of claim 1, wherein the first step of processing comprises epitaxially growing a group III nitride material layer on the monocrystal wafer.

4. The method of claim 3, wherein the first step of processing further comprises processing said group III nitride material layer to develop pores.

5. The method of claim 1, wherein said monocrystal material is made of group III nitride material.

6. The method of claim 1, where said monocrystal wafer is made of silicon carbide.

7. The method of claim 6, wherein the silicon carbide wafer have surface orientation (0001).

8. The method of claim 1, wherein said epitaxially grown monocrystal layer is group III nitride semiconductor.

9. The method of claim 1, wherein said monocrystal material is made of silicon carbide.

10. The method of claim 1, further comprising the step of removing said porous monocrystal layer containing the voids.

11. The method of claim 1, wherein said voids are formed by heating said porous monocrystal layer.

12. The method of claim 1, wherein said voids are formed by annealing in vacuum.

13. The method of claim 12, wherein the annealing is performed in a temperature range from about 950 to about 1000°

C.

14. The method of claim 1, wherein said voids are arranged at spacings higher than 0.1 micron.

15. The method of claim 1, wherein said voids have largest dimensions perpendicular to the [0001] crystallographic direction.

16. The method of claim 1, wherein said voids have size in a range from 1 to few hundred microns.

17. The method of claim 1, wherein said voids form continues cavities inside said monocrystal wafer.

18. The method of claim 1, wherein said voids are distributed uniformly over said monocrystal wafer.

19. The method of claim 1, wherein said porous layer has thickness from about 2.5 microns to about 5 microns.

20. The method of claim 1, wherein the said voids have thickness ranging from about 1 micron to about 3 microns.

21. The method of claim 1, wherein said voids have length ranging from about 1 micron to 100 microns.

22. The method of claim 1, wherein said voids are located inside said monocrystal wafer between the porous layer and a nonporous portion of the wafer.

23. The method of claim 1, wherein said voids are located at a distance of about 1 micron or more from wafer surface.

24. The method of claim 1, wherein said epitaxially grown monocrystal layer has thickness more than about 1 mm.