Single step pendeo-and lateral epitaxial overgrowth of group III-nitride epitaxial layers with group III-nitride buffer layer and resulting structures

• US 6,582,986 B2
• Filed: 08/21/2001
• Issued: 06/24/2003
• Est. Priority Date: 10/14/1999
• Status: Expired due to Term

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Edmond, John Adam, Haberern, Kevin Ward, Emerson, David Todd, Kong, Hua-Shuang
• Primary Examiner(s): Nelms, David
• Assistant Examiner(s): Dang, Phuc T.
• Application Number:
  US09/934,270
• Publication Number:
  US 20020022290A1
• Time in Patent Office: 672 Days
• Field of Search: 438/44, 438/48, 438/51, 438/56, 438/58, 438/64, 438/481, 438/532, 438/551, 438/552, 438/553, 438/931
• US Class Current: 438/48
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/02491 Conductive materials
• CPC Class Codes: H01L 21/0254 Nitrides
• 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 21/02642 Mask materials other than SiO2 or SiN
• CPC Class Codes: H01L 21/02647 Lateral overgrowth
• 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
• CPC Class Codes: H01S 5/320225 polar orientation

Abstract

A method of fabricating a gallium nitride-based semiconductor structure on a substrate includes the steps of forming a mask having at least one opening therein directly on the substrate, growing a buffer layer through the opening, and growing a layer of gallium nitride upwardly from the buffer layer and laterally across the mask. During growth of the gallium nitride from the mask, the vertical and horizontal growth rates of the gallium nitride layer are maintained at rates sufficient to prevent polycrystalline material nucleating on said mask from interrupting the lateral growth of the gallium nitride layer. In an alternative embodiment, the method includes forming at least one raised portion defining adjacent trenches in the substrate and forming a mask on the substrate, the mask having at least one opening over the upper surface of the raised portion. A buffer layer may be grown from the upper surface of the raised portion. The gallium nitride layer is then grown laterally by pendeoepitaxy over the trenches.

Claims

1. A method of fabricating a gallium nitride-based semiconductor structure on a substrate, the method comprising:

forming a mask on a substrate that includes both at least one trench and at least one raised portion adjacent said trench, and with said mask having at least one opening therein on said raised portion of said substrate;

growing a buffer layer on said raised portion of said substrate within said opening in said mask; and

growing an epitaxial layer selected from the group consisting of gallium nitride and Group III nitride alloys of gallium nitride upwardly from said buffer layer and laterally across said trench.

2. A fabrication method according to claim 1 comprising growing the buffer layer to a thickness greater than the thickness of the mask.

3. A fabrication method according to claim 1 comprising forming at least two raised portions adjacent to the trench and growing the epitaxial layer until it coalesces over the trench.

4. A fabrication method according to claim 1 wherein the step of forming the mask comprises forming the mask and then forming the opening therein.

5. A fabrication method according to claim 1 comprising forming the mask on a silicon carbide substrate.

6. A method of fabricating a gallium nitride-based semiconductor structure on a substrate, the method comprising:

forming at least one trench in a substrate to thereby define both the trench and a raised portion immediately adjacent the trench;

forming a mask on the trenched substrate with the mask having at least one opening therein on the raised portion of the substrate;

growing a buffer layer on the raised portion of the substrate through the opening in the mask; and

growing an epitaxial layer selected from the group consisting of gallium nitride and Group III nitride alloys of gallium nitride upwardly from the buffer layer and laterally across the trench.

7. A fabrication method according to claim 6 wherein the step of forming the trench comprising etching the trench in the substrate.

8. A fabrication method according to claim 7 wherein the etching step comprises a reactive ion etch.

9. A fabrication method according to claim 6 wherein the step of forming the buffer comprises forming the buffer using vapor phase epitaxy.

10. A fabrication method according to claim 6 comprising growing the buffer layer to a thickness greater than the thickness of the mask.

11. A fabrication method according to claim 6 comprising forming at least two raised portions adjacent to the trench and growing the epitaxial layer until it coalesces over the trench portion.

12. A fabrication method according to claim 6 wherein the step of forming the mask comprises forming the mask and then forming the opening therein.

13. A fabrication method according to claim 6 comprising forming the mask using a technique selected from the group consisting of plasma-enhanced chemical vapor deposition, sputtering, reactive sputtering, electron-beam deposition and thermal oxidation.

14. A method of fabricating a gallium nitride-based semiconductor structure on a substrate, the method comprising:

forming a mask on a substrate that includes bath at least one trench and at least two raised portions adjacent said trench, and with said mask having at least one opening therein on said raised portion of said substrate;

growing a buffer layer on said raised portion of said substrate within said opening in said mask; and

growing an epitaxial layer selected from the group consisting of gallium nitride and Group III nitride alloys of gallium nitride upwardly from said buffer layer and laterally across said trench until it coalesces over said trench.

15. A method of fabricating a gallium nitride-based semiconductor structure on a substrate, the method comprising:

forming at least one trench in a substrate to thereby define both the trench and at least two raised portions immediately adjacent the trench;

forming a mask on the trenched substrate with the mask having at least one opening therein on the raised portion of the substrate;

growing a buffer layer on the raised portion of the substrate through the opening in the mask; and

growing an epitaxial layer selected from the group consisting of gallium nitride and Group III nitride alloys of gallium nitride upwardly from the buffet layer and laterally across the trench until it coalesces over the trench.