METHOD FOR NONDESTRUCTIVE LIFT-OFF OF GaN FROM SAPPHIRE SUBSTRATE UTILIZING A SOLID-STATE LASER

• US 20110201191A1
• Filed: 04/21/2009
• Published: 08/18/2011
• Est. Priority Date: 11/07/2008
• Status: Active Grant

• Current Assignee: Guoyi Zhang, Xiangning Kang, Xinrong Yang, Yongjian Sun, Zhijian Yang, Zhizhong Chen
• Original Assignee: Guoyi Zhang, Xiangning Kang, Xinrong Yang, Yongjian Sun, Zhijian Yang, Zhizhong Chen
• Inventors: Sun, Yongjian, Yang, Zhijian, Zhang, Guoyi, Chen, Zhizhong, Kang, Xiangning, Yang, Xinrong
• Granted Patent: US 8,338,313 B2
• Time in Patent Office: Days
• US Class Current: 438/604
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: C30B 25/18 characterised by the substrate
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 33/06 Joining of crystals
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate

Abstract

A method for nondestructive laser lift-off of GaN from sapphire substrates utilizing a solid-state laser is disclosed in the present invention, wherein, a solid-state laser is used as the laser source, and a small laser-spot with a circumference of 3 to 1000 micrometers and a distance of two farthest corners or a longest diameter of no more than 400 micrometers is used for laser scanning point-by-point and line-by-line, wherein the energy in the small laser-spot is distributed such that the energy in the center of the laser-spot is the strongest and is gradually reduced toward the periphery. According to the present invention, a nondestructive laser lift-off with a small laser-spot is achieved, and a scanning mode of the laser lift-off is improved, thereby a lift-off method without the need of aiming is achieved. As a result, the laser lift-off process is simplified, and the efficiency is improved while the rejection rate is reduced, such that the obstacles of the industrialization of the laser lift-off process are removed.

Claims

1. A method for non-destructively lifting a III-V semiconductor device from a sapphire substrate, comprising:

obtaining a III-V semiconductor layer grown on a sapphire substrate at an interface;

irradiating a laser beam through the sapphire substrate, wherein the laser beam forms a laser spot at the interface between the III-V semiconductor layer and the sapphire substrate, wherein the laser spot has a distance between two farthest corners or a longest diameter smaller than 400 μ

m; and

scanning the laser beam across the interface between the III-V semiconductor layer and the sapphire substrate to form a plurality of laser spots at the interface to non-destructively separate the III-V semiconductor layer from the sapphire substrate.

2. The method of claim 1, wherein the perimeter of the laser spot has a distance between two farthest corners or a longest diameter no more than 150 micrometers.

3. The method of claim 1, wherein the perimeter of the laser spot has a length between about 3 μ

m and 1000 μ

m.

5. The method of claim 1, wherein the laser spot at the interface has a width of about 30 microns μ

m.

21. The method of claim 1, wherein the laser spot at the interface has a width of about 100 microns μ

m.

22. The method of claim 1, wherein the distance between the centers of adjacent laser spots is about the same as the width of the laser spot.

23. The method of claim 1, wherein the distance between the centers of adjacent laser spots at the interface is in a range of about 30 μ

m and about 100 μ

m.

24. The method of claim 1, wherein the laser spot at the interface has a shape selected from the group consisting of a square, a rectangle, a polygon, a circle, and an elliptical.

25. The method of claim 1, wherein the laser spot has a substantially Gaussian energy distribution at the interface between the III-V semiconductor layer and the sapphire substrate.

26. The method of claim 1, wherein the laser beam is emitted by a solid-state laser device.

27. The method of claim 1, further comprising:

bonding a conductive layer on a surface of the III-V semiconductor layer opposing the interface between the III-V semiconductor layer and the sapphire substrate.

28. The method of claim 27, wherein the conductive layer comprises copper, the method further comprising:

depositing a palladium layer on the surface III-V semiconductor layer;

depositing an Indium layer on the palladium layer; and

bonding the conductive layer to the indium layer.

29. The method of claim 28, wherein the palladium layer is deposited on the surface III-V semiconductor layer by sputtering, wherein the Indium layer is deposited on the palladium layer by thermal evaporation.

30. The method of claim 1, wherein the III-V semiconductor material comprises GaN.

31. The method of claim 1, wherein the III-V semiconductor material comprises a nitride material.

6-20. -20. (canceled)

32. A method for non-destructively lifting a III-V semiconductor device from a sapphire substrate, comprising:

obtaining a III-V semiconductor layer grown on a sapphire substrate at an interface;

irradiating a laser beam through the sapphire substrate, wherein the laser beam forms a laser spot at the interface between the III-V semiconductor layer and the sapphire substrate, wherein the perimeter of the laser spot has a length between about 3 μ

m and 1000 μ

m; and

scanning the laser beam across the interface between the III-V semiconductor layer and the sapphire substrate to form a plurality of laser spots at the interface to non-destructively separate the III-V semiconductor layer from the sapphire substrate.

33. The method of claim 32, wherein the perimeter of the laser spot has a length between about 100 μ

m and 400 μ

m.

34. The method of claim 32, wherein the laser spot has a distance between two farthest corners or a longest diameter smaller than 400 μ

m.

35. The method of claim 32, wherein the laser beam is emitted by a solid-state laser device.