Method of fabricating optical devices using laser treatment

• US 9,786,810 B2
• Filed: 05/04/2015
• Issued: 10/10/2017
• Est. Priority Date: 11/09/2010
• Status: Active Grant

• Current Assignee: Kyocera SLD Laser Incorporated (Kyocera Corporation)
• Original Assignee: Soraa Laser Diode, Inc. (Kyocera Corporation)
• Inventors: Pfister, Nicholas J., Raring, James W., Schmidt, Mathew
• Primary Examiner(s): Pizaro, Marcos D
• Assistant Examiner(s): Tang, Sue
• Application Number:
  US14/703,767
• Publication Number:
  US 20150236196A1
• Time in Patent Office: 890 Days
• Field of Search: 257 12- 14, 257 79-103, 257918, 257E51018-E51022, 257E33001-E33077, 257E25028, 257E25032
• CPC Class Codes: H01L 29/20 including, apart from doping materials or other impurities, only AIIIBV compounds
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01S 5/0014 Measuring characteristics or properties thereof measuring techniques per se G01J, G01K, G01N, G01R
• CPC Class Codes: H01S 5/0202 Cleaving
• CPC Class Codes: H01S 5/0203 Etching
• CPC Class Codes: H01S 5/0421 characterised by the semiconducting contacting layers electrodes H01S5/0425
• CPC Class Codes: H01S 5/2013 MQW barrier reflection layers
• CPC Class Codes: H01S 5/2201 in a specific crystallographic orientation
• CPC Class Codes: H01S 5/3013 AIIIBV compounds
• CPC Class Codes: H01S 5/32025 non-polar orientation
• CPC Class Codes: H01S 5/32341 blue laser based on GaN or GaP

Abstract

A method for forming optical devices. The method includes providing a gallium nitride substrate member having a crystalline surface region and a backside region. The method also includes subjecting the backside region to a laser scribing process to form a plurality of scribe regions on the backside region and forming a metallization material overlying the backside region including the plurality of scribe regions. The method removes at least one optical device using at least one of the scribe regions.

Claims

1. A method for forming optical devices comprising:

providing a gallium and nitrogen containing substrate member having a crystalline surface region and a backside opposite the crystalline surface region;

forming a laser stripe region overlying a portion of the crystalline surface region;

subjecting the backside to a laser scribing process to form a plurality of scribe regions on the backside, at least one of the plurality of scribe regions underlying at least a portion of the laser stripe region, each of the plurality of scribe regions comprising a recessed region extending partially through a thickness of the gallium and nitrogen containing substrate, wherein portions of the backside within a vicinity of the plurality of scribe regions have a higher conductivity than portions of the backside outside the vicinity of the plurality of scribe regions;

forming a metallization material overlying the backside including at least a portion of the plurality of scribe regions; and

removing at least one optical device from the gallium and nitrogen containing substrate member using at least one of the plurality of scribe regions.

2. The method of claim 1 further comprising:

subjecting the backside including the plurality of scribe regions to a first treatment process to remove native oxide from the backside; and

subjecting the backside including the plurality of scribe regions to a second treatment process to remove one or more particles of metallization or laser slag from a vicinity of the plurality of scribe regions.

3. The method of claim 2 wherein the second treatment process comprises an HCl etch process;

and wherein the removing comprises one or more singulation processes.

4. The method of claim 1 wherein the metallization material comprises at least one of an Al/Ni/Au stack, an AI/Pt/Au stack, or a Ti/Pt/Au stack.

5. The method of claim 1 further comprising lapping and polishing the backside region before the laser scribing process.

6. The method of claim 1 wherein the metallization material is an n-contact region having a desired resistivity.

7. The method of claim 1 wherein the optical device is characterized by an operating voltage of less than 7.5V, less than 6.5V, less than 5.5V, less than 4.5V, or less than 3.5V.

8. The method of claim 1 wherein the laser scribing process anneals one or more portions of the gallium nitride substrate.

9. The method of claim 1 wherein the laser scribing process causes formation of a higher impurity region within a vicinity of one or more scribe regions.

10. The method of claim 1 wherein the metallization material forms overlying each of the plurality of scribe regions including edges of the plurality of scribe regions.

11. The method of claim 1 wherein the recessed region extends between 3 μ

m and 5 μ

m into the gallium and nitrogen containing substrate.

12. A method for forming optical devices comprising:

providing a gallium and nitrogen containing substrate member having a crystalline surface region and a backside opposite the crystalline surface region;

subjecting the backside to a laser scribing process to form a plurality of ablated regions characterized by a v-shaped or a trench-shaped profile on the backside of the gallium and nitrogen containing substrate, where sides and a bottom of the plurality of ablated regions have a higher gallium concentration than surfaces of the backside of the gallium and nitrogen containing substrate that are laterally spaced from the plurality of ablated regions;

forming a metal contact on the backside of the gallium and nitrogen containing substrate that covers at least a portion of the plurality of ablated regions; and

removing at least one optical device from the gallium and nitrogen containing substrate member using at least one of the plurality of ablated regions.

13. The method of claim 12 wherein the optical device comprises a light emitting diode device.

14. The method of claim 12 wherein the optical device comprises a laser device.

15. The method of claim 12 wherein the crystalline surface region is configured in at least one of a non-polar orientation, a semi-polar orientation, an m-plane orientation having a +/−

6 degree off-cut, or a {20-21} orientation.

16. The method of claim 12 wherein one or more of the ablated regions is arranged in at least one spatial configuration including an annular segment, a circular segment, a straight line segment, an irregular line segment, in a parallel manner, or other combinations.

17. The method of claim 12 wherein the laser scribing process is provided from a 355 nm UV source.

18. A method for forming optical devices comprising:

providing a gallium and nitrogen containing substrate member having a crystalline surface region and a backside opposite the crystalline surface region, the crystalline surface region configured in a non-polar or semi-polar orientation;

forming one or more active regions overlying a portion of the crystalline surface region, the one or more active regions configured to emit electromagnetic radiation for an optical device;

forming a metallization material overlying the crystalline surface region;

subjecting the crystalline surface region to a laser treatment process to change an operating voltage of the optical device from a first value to a second value, the second value being less than the first value by at least 10 percent, the laser treatment process also causing formation of at least one scribe region on the surface region, the at least one scribe region comprising a recessed region extending through the crystalline surface region and partially through the gallium and nitrogen containing substrate, wherein portions of the crystalline surface region within a vicinity of the at least one scribe region have a higher conductivity than portions of the crystalline surface region outside the vicinity of the at least one scribe region; and

removing the optical device using the at least the scribe region.

19. The method of claim 18 wherein the forming of the metallization material is provided after the laser treatment process;

and wherein the removing further comprising a breaking process.