Etching technique for the fabrication of thin (Al, In, Ga)N layers

• US 7,795,146 B2
• Filed: 04/13/2006
• Issued: 09/14/2010
• Est. Priority Date: 04/13/2005
• Status: Active Grant

• Current Assignee: Japan Science & Technology Trading Co. Limited
• Original Assignee: Japan Science & Technology Trading Co. Limited, Regents of the University of California (University of California)
• Inventors: Speck, James S., Baker, Troy J., Haskell, Benjamin A., Pattison, P. Morgan
• Primary Examiner(s): Bryant; Kiesha R
• Assistant Examiner(s): WRIGHT, TUCKER J
• Application Number:
  US11/403,288
• Publication Number:
  US 20060246722A1
• Time in Patent Office: 1,615 Days
• Field of Search: 438/458, 438/689, 438/705, 438/745
• US Class Current: 438/689
• CPC Class Codes: H01L 21/2654 in AIIIBV compounds
• CPC Class Codes: H01L 21/26546 of electrically active species
• CPC Class Codes: H01L 21/30612 Etching of AIIIBV compounds
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

An etching technique for the fabrication of thin (Al, In, Ga)N layers. A suitable template or substrate is selected and implanted with foreign ions over a desired area to create ion implanted material. A regrowth of a device structure is then performed on the implanted template or substrate. The top growth surface of the template is bonded to a carrier wafer to created a bonded template/carrier wafer structure. The substrate is removed, as is any residual material, to expose the ion implanted material. The ion implanted material on the bonded template/carrier wafer structure is then exposed to a suitable etchant for a sufficient time to remove the ion implanted material.

Claims

1. A method of etching thin epitaxially-grown nitride layers, comprising:

(a) selecting a suitable template or substrate;

(b) implanting the template or substrate with foreign ions over a desired area to create ion implanted material;

(c) performing a regrowth of a nitride device structure on the implanted template or substrate;

(d) bonding an exposed growth surface of the nitride device structure to a carrier wafer, so that the nitride device structure is positioned between the carrier wafer and the implanted template or substrate, to create a bonded nitride device structure/carrier wafer structure; and

(e) exposing the ion implanted material on the bonded nitride device structure/carrier wafer structure to a suitable etchant for a sufficient time to remove the ion implanted material from a surface of the implanted template or substrate opposite the nitride device structure, so that the surface of the implanted template or substrate is planar on a nanometer scale.

2. The method of claim 1, further comprising removing a portion of the template or substrate from the nitride device structure/carrier wafer structure after the bonding step (d) and before performing the exposing step (e).

3. The method of claim 2, further comprising removing any residual material to expose the ion implanted material after removing the template or substrate and before performing the exposing step (e).

4. The method of claim 1, wherein the desired area is an entire wafer.

5. The method of claim 1, wherein the exposing step (e) comprises performing a chemical etching process in which etching proceeds in a lateral fashion to separate the regrowth from the substrate.

6. The method of claim 1, wherein the exposing step (e) comprises selectively etching the ion implanted material to an etch stop below the template or substrate surface and defined by an implantation profile or damage layer.

7. The method of claim 1, wherein the template or substrate is removed either over at least one selected area or completely to form at least one nitride membrane structure or at least one thick nitride wafer.

8. The method of claim 1, wherein the template or substrate surface remains intact following the implanting step (b) so as to provide a high quality crystalline surface for the regrowth.

9. The method of claim 1, wherein the implanting step (b) comprises selecting a dose and an implanted species of ion such that implanted ions do not diffuse enough to coalesce into bulk voids when heated to a growth temperature.

10. The method of claim 1, wherein the implanting step (b) comprises selecting an implantation profile or damage layer for the implanting step (b).

11. The method of claim 10, wherein the implantation profile determines an etch rate and a risk of crystallographic etching for the ion implanted material.

12. The method of claim 10, wherein the implantation profile or damage layer extends from a few tens of nanometers below the template or substrate surface through a thickness of the template or substrate.

13. The method of claim 1, wherein:

(1) the implanting is below the surface of the template or substrate such that the surface of the template or substrate remains intact following the implantation process, thereby providing a crystalline surface suitable for regrowth on the surface of the template or substrate; and

(2) the nitride structure/carrier wafer structure is etched from a surface different from a growth surface of the nitride device structure regrowth, thereby minimizing damage to the nitride device structure regrowth.

14. The method of claim 13, wherein the nitride structure/carrier wafer structure is etched from a backside opposite the growth surface, thereby minimizing damage to the nitride device structure regrowth.