Cantilever epitaxial process

• US 6,599,362 B2
• Filed: 01/03/2001
• Issued: 07/29/2003
• Est. Priority Date: 01/03/2001
• Status: Expired due to Term

• Current Assignee: National Technology & Engineering Solutions Of Sandia LLC (Honeywell International Inc.)
• Original Assignee: Sandia Corporation (Martin Marietta Corporation)
• Inventors: Han, Jung, Follstaedt, David M., Ashby, Carol I., Mitchell, Christine C.
• Primary Examiner(s): KUNEMUND, ROBERT M
• Application Number:
  US09/754,803
• Publication Number:
  US 20020090816A1
• Time in Patent Office: 937 Days
• Field of Search: 117/952, 117/956, 117/94, 117/95, 117/97, 117/106
• US Class Current: 117/94
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/02439 Materials
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02521 Materials
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02587 Structure
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02639 Preparation of substrate for selective deposition
• CPC Class Codes: H01L 21/0265 Pendeoepitaxy
• CPC Class Codes: H01S 2304/12 Pendeo epitaxial lateral overgrowth [ELOG], e.g. for growing GaN based blue laser diodes

Abstract

A process of growing a material on a substrate, particularly growing a Group II-VI or Group III-V material, by a vapor-phase growth technique where the growth process eliminates the need for utilization of a mask or removal of the substrate from the reactor at any time during the processing. A nucleation layer is first grown upon which a middle layer is grown to provide surfaces for subsequent lateral cantilever growth. The lateral growth rate is controlled by altering the reactor temperature, pressure, reactant concentrations or reactant flow rates. Semiconductor materials, such as GaN, can be produced with dislocation densities less than 10⁷/cm².

Claims

1. A process for cantilever growth of a material, comprising:

etching a pattern onto a substrate, said pattern comprising at least one cantilever support region;

forming a nucleation layer on said substrate;

growing in a reactor by a vapor-phase growth technique a middle layer on said nucleation layer on said substrate, said middle layer providing surfaces for subsequent lateral cantilever growth;

growing in said reactor without an intermediate removal step on said middle layer a growth layer of material with a lateral growth rate of the growth layer approximately equal to or greater than the vertical growth rate relative to the orientation of the substrate, said middle layer remaining maskless.

2. The process of claim 1 wherein the substrate is a material selected from an aluminum oxide material, SiC, Si(111), ZnO, MgO, LiGaO₂, GaAs, a Group III-V material, and a Group II-VI material.

3. The process of claim 1 wherein said vapor-phase growth technique is selected from metalorganic chemical vapor deposition, organometallic vapor-phase epitaxy, molecular beam epitaxy, and halide vapor-phase epitaxy.

4. The process of claim 1 wherein the nucleation layer is selected from Group III-V materials, Group II-VI materials, and SiGe, wherein the Group III materials include at least one of B, Al, Ga, In and TI, the Group V materials include at least one of N, P, As, Sb, the Group II materials include at least one of Zn, Cd, Hg, and the Group VI materials include at least one of O, S, Se, and Te.

5. The process of claim 1 wherein the middle layer is selected from Group III-V materials, Group II-VI materials, and SiGe, wherein the Group III materials include at least one of B, Al, Ga, In and TI, the Group V materials include at least one of N, P, As, Sb, the Group II materials include at least one of Zn, Cd, Hg, and the Group VI materials include at least one of O, S, Se, and Te.

6. The process of claim 1 wherein the growth layer is selected from Group III-V materials, Group II-VI materials, and SiGe, wherein the Group III materials include at least one of B, AL, Ga, In and TI, the Group V materials include at least one of N, P, As, Sb, the Group II materials include at least one of Zn, Cd, Hg, and the Group VI materials include at least one of O, S, Se, and Te.

7. The process of claim 6 wherein the growth layer is a Group III-V material wherein the Group III materials include at least one of B, Al, Ga, In and TI, and the Group V materials include at least one of N, P, As, Sb.

8. The process of claim 7 wherein the dislocation density is less than approximately 10⁷/cm².

9. The process of claim 1 wherein the surfaces provided by the middle layer form a plateau geometry.

10. The process of claim 1 wherein the surfaces provided by the middle layer form a pyramidal geometry.

11. The process of claim 1 wherein the lateral growth rate and the vertical growth rate are controlled by altering reaction process conditions, said reaction process conditions selected from temperature, pressure, reactant concentrations, and reactant flow rates.

12. The process of claim 1 comprising the further step of growing an additional growth layer on top of the existing growth layer.

13. The process of claim 7 wherein the growth layer is a Group III-N material wherein the Group III materials include at least one of B, Al, Ga, In and TI.

14. The process of claim 13 wherein the nucleation layer is a Group III-N material, the middle layer is a Group III-N material and the growth layer is a Ga—

N material, said Ga—

N material having a dislocation density less than approximately 10⁷/cm².

15. The process of claim 14 wherein the nucleation layer is less than approximately 500 angstroms thick and the middle layer is less than approximately 1 micrometer thick.

16. A process for cantilever growth of a Group III-N material, comprising:

etching a pattern onto a substrate, said pattern comprising at least one cantilever support region;

forming a nucleation layer on said substrate, said nucleation layer selected from a Group III-N material;

growing in a reactor by a vapor-phase growth technique a Group III-N middle layer on said nucleation layer on said substrate, said middle layer less than approximately 1 micrometer in thickness and providing surfaces for subsequent lateral cantilever growth;

growing in said reactor at approximately 1100°

C. without an intermediate removal step on said middle layer a growth layer of a Group III-N material with a lateral growth rate of the growth layer approximately equal to or greater than the vertical growth rate relative to the orientation of the substrate, said middle layer remaining maskless.

17. The process of claim 16 wherein the growth layer is selected from a Ga—

N material, an AlGaN material, an InGaN material and an AlGaInN material.

18. The process of claim 16 wherein the processing steps of growing the nucleation layer, growing the middle layer, and growing the growth layer occur without removal of the substrate from the reactor.

19. A process for cantilever growth of a material, comprising:

etching a pattern onto a substrate, said pattern comprising at least one cantilever support region and at least one trench;

forming a nucleation layer on said substrate;

growing in a reactor by a vapor-phase growth technique a middle layer on said nucleation layer on said substrate, said middle layer providing surfaces for subsequent lateral cantilever growth;

growing in said reactor without an intermediate removal step on said middle layer a growth layer of material wherein the growth is stopped prior to the lateral cantilever growth originating from the cantilever support region coalescing with the growth layer originating from the trench.

20. The process of claim 19 wherein the growth of the growth layer has a lateral growth rate less than the vertical growth rate.

21. The process of claim 19 wherein the growth of the growth layer has a lateral growth rate greater than the vertical growth rate.