GaN-based composite substrate, GaN-based device and method for manufacturing the same

Abstract

The application provides a GaN-based composite substrate, a GaN-based device and a manufacturing method thereof. The GaN-based composite substrate comprises an isolation substrate, a GaN-based substrate and a bonding layer between the isolation substrate and the GaN-based substrate. The GaN-based composite substrate is used to replace a GaN-based material substrate. The composite substrate bonds the GaN-based substrate and the isolation substrate together through the bonding layer. The isolation substrate has no defects extending along the thickness direction. The isolation substrate can block the path of the downward leakage of the chemical etching liquid through the holes in the GaN-based substrate, avoid the pollution of the machine and the production line, and thus a GaN-based device layer with good quality can be obtained, and the yield of the GaN-based device is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor, in particular to a GaN-based composite substrate, a GaN-based device and a manufacturing method thereof. BACKGROUND

[0002] III-nitride is the third generation of new semiconductor materials after Si, GaAs and other first and second generation semiconductor materials. GaN as a wide band gap semiconductor material has many advantages, such as high saturation drift speed, large breakdown voltage, excellent carrier transport performance, and the ability to form AlGaN, InGaN ternary alloy and AlInGaN quaternary alloy, etc., and it is easy to make GaN-based PN junction. In view of this, in recent years, GaN-based materials and semiconductor devices have been widely and deeply researched, and MOCVD (Metal-organic Chemical Vapor Deposition) technology for growing GaN-based materials is becoming mature; in the research of semiconductor devices, GaN-based LED, LD and other optoelectronic devices and GaN-based HEMT and other microelectronic devices have made remarkable achievements and great progress.

[0003] The yield, also known as the "pass rate", is an important indicator of the quality of semiconductor products, which refers to the percentage of qualified products in all processed products. How to improve the yield of GaN-based devices is a technical problem that needs to be solved in the industry. SUMMARY

[0004] The purpose of the present application is to provide a GaN-based composite substrate, a GaN-based device and a manufacturing method thereof, to improve the yield of GaN-based devices.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a GaN-based composite substrate, comprising: an isolation substrate, a GaN-based substrate, and a bonding layer between the isolation substrate and the GaN-based substrate.

[0006] Optionally, the material of the GaN-based substrate comprises GaN or AlGaN.

[0007] Optionally, the GaN-based substrate is a single-layer structure or a laminated structure.

[0008] Optionally, the material of the isolation substrate is monocrystalline silicon or aluminum oxide.

[0009] Optionally, the isolation substrate is a single-layer structure or a laminated structure.

[0010] Optionally, the material of the bonding layer is at least one of aluminum, gold, silicon-gold alloy, gold-tin alloy, and copper-tin alloy.

[0011] The second aspect of the present application provides a GaN-based device, comprising: the GaN-based composite substrate according to any one of the above, and a GaN-based device layer on the GaN-based composite substrate, the GaN-based device layer being close to the GaN-based substrate.

[0012] The third aspect of the present application provides a method for manufacturing a GaN-based device, comprising:

[0013] epitaxially growing a GaN-based device layer on the GaN-based composite substrate, the GaN-based device layer being close to the GaN-based substrate;

[0014] peeling off the isolation substrate.

[0015] Optionally, the peeling off of the isolation substrate comprises: melting the bonding layer by heating; or chemically etching the bonding layer.

[0016] For how to improve the yield of GaN-based devices, various schemes are adopted in the related art, such as adopting a better device structure design, using more reasonable process parameters, etc. However, the present inventors have found through analysis of the process that one of the reasons for the reduction in yield is that GaN-based materials more or less have defects, mainly some holes extending along the thickness direction, which causes some chemical etching liquids, such as developing liquid, etc., to seep downward through the holes in the process of using GaN-based materials as substrates to manufacture GaN-based devices, causing pollution of the machine and the production line.

[0017] To solve the above problems, one scheme is to improve the quality of GaN-based materials, reducing or even avoiding defects. This scheme has a high cost, and the process direction is not clear.

[0018] Compared with the prior art, the present application has the beneficial effects that:

[0019] The present application uses a GaN-based composite substrate to replace a GaN-based material substrate, the composite substrate bonds the GaN-based substrate and the isolation substrate together through a bonding layer, the isolation substrate has no defects extending along the thickness direction, and can block the path of the downward seepage of the chemical etching liquid through the holes in the GaN-based substrate, avoiding pollution of the machine and the production line, so that a GaN-based device layer with good quality can be obtained, and the yield of GaN-based devices can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a schematic diagram of the cross-sectional structure of a GaN-based composite substrate according to the first embodiment of the present application;

[0021] Figure 2 is a schematic diagram of the cross-sectional structure of a GaN-based composite substrate according to the second embodiment of the present application;

[0022] Figure 3is a schematic diagram of a cross-sectional structure of a GaN-based composite substrate of a third embodiment of the present application;

[0023] Figure 4 is a schematic diagram of a cross-sectional structure of a GaN-based device of a fourth embodiment of the present application;

[0024] Figure 5 is a schematic diagram of a cross-sectional structure of a GaN-based device of a fifth embodiment of the present application;

[0025] Figure 6 is a flowchart of a method for manufacturing a GaN-based device of Figure 5

[0026] For the convenience of understanding the present application, all the reference signs appearing in the present application are listed as follows:

[0027] GaN-based composite substrate 1, 2, 3 isolation substrate 10

[0028] GaN-based substrate 11 bonding layer 12

[0029] first isolation substrate 101 second isolation substrate 102

[0030] first GaN-based substrate 111 second GaN-based substrate 112

[0031] GaN-based device 4, 5 GaN-based device layer 21 DETAILED DESCRIPTION

[0032] In order to make the above objectives, features and advantages of the present application more apparent and comprehensible, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0033] Figure 1 is a schematic diagram of a cross-sectional structure of a GaN-based composite substrate of a first embodiment of the present application.

[0034] Referring to Figure 1 , the GaN-based composite substrate 1 comprises an isolation substrate 10, a GaN-based substrate 11, and a bonding layer 12 between the isolation substrate 10 and the GaN-based substrate 11.

[0035] In the present embodiment, both the isolation substrate 10 and the GaN-based substrate 11 are single-layer structures. The material of the single-layer isolation substrate 10 can be monocrystalline silicon or aluminum oxide. The manufacturing process of the monocrystalline silicon substrate is mature, and it has fewer lattice defects. The aluminum oxide structure is dense, and both of them can play a role in plugging the liquid from flowing downward. The material of the single-layer GaN-based substrate 11 can be GaN or AlGaN. The material of the single-layer GaN-based substrate 11 can be reasonably selected based on the specific material of subsequent epitaxial growth.

[0036] ​The material of the bonding layer 12 can be at least one of metallic aluminum, metallic gold, silicon-gold alloy, gold-tin alloy, and copper-tin alloy. The above-mentioned materials can realize firm bonding between the separation substrate 10 and the GaN-based substrate 11, and are easy to melt when heated, facilitating the separation of the separation substrate 10 from the GaN-based substrate 11.

[0037] Figure 2 FIG. 4 is a schematic diagram of a cross-sectional structure of a GaN-based composite substrate according to a second embodiment of the present application.

[0038] Referring to Figure 2 and Figure 1 , the GaN-based composite substrate 2 of the second embodiment is substantially the same as the GaN-based composite substrate 1 of the first embodiment, except that the separation substrate 10 includes a first separation substrate 101 and a second separation substrate 102, and the second separation substrate 102 is close to the bonding layer 12. In other words, the separation substrate 10 is a laminated structure.

[0039] The material of the first separation substrate 101 can be single-crystal silicon, and the material of the second separation substrate 102 can be aluminum oxide. The laminated structure can further prevent liquid from flowing downward to the machine table, compared with the single-layer structure.

[0040] In other embodiments, the laminated structure can include three or more layers.

[0041] Figure 3 FIG. 5 is a schematic diagram of a cross-sectional structure of a GaN-based composite substrate according to a third embodiment of the present application.

[0042] Referring to Figure 3 , Figure 2 and Figure 1 , the GaN-based composite substrate 3 of the third embodiment is substantially the same as the GaN-based composite substrates 1, 2 of the first and second embodiments, except that the GaN-based substrate 11 includes a first GaN-based substrate 111 and a second GaN-based substrate 112, and the first GaN-based substrate 111 is close to the bonding layer 12. In other words, the GaN-based substrate 11 is a laminated structure.

[0043] The defect density of the second GaN-based substrate 112 is less than that of the first GaN-based substrate 111, so as to improve the quality of a GaN-based device layer to be subsequently epitaxially grown. The materials of the first GaN-based substrate 111 and the second GaN-based substrate 112 can be the same or different.

[0044] Figure 4 FIG. 6 is a schematic diagram of a cross-sectional structure of a GaN-based device according to a fourth embodiment of the present application.

[0045] Referring to Figure 4As shown, the GaN-based device 4 comprises any of the GaN-based composite substrates 1, 2, 3 and a GaN-based device layer 21 on the GaN-based composite substrate 1, 2, 3, the GaN-based device layer 21 being close to the GaN-based substrate 11.

[0046] The GaN-based device layer 21 can comprise an epitaxial growth process and a patterning process.

[0047] Since the isolation substrate 10 of the GaN-based composite substrate 1, 2, 3 has no defects extending along the thickness direction, the path for the chemical etching liquid to seep downward through the hole in the GaN-based substrate 11 can be blocked, thus avoiding contamination of the machine and the production line, and a GaN-based device layer 21 of good quality can be obtained, thereby improving the yield of the GaN-based device 4.

[0048] Figure 5 is a schematic diagram of the cross-sectional structure of a GaN-based device according to a fifth embodiment of the present application.

[0049] Referring to Figure 5 and Figure 4 As shown, the GaN-based device 5 of the fifth embodiment is substantially the same as the GaN-based device 4 of the fourth embodiment, except that the isolation substrate 10 and the bonding layer 12 are peeled off.

[0050] The GaN-based device 5 is conducive to device thinning and heat dissipation.

[0051] Figure 6 is a flowchart of a method for manufacturing a GaN-based device. Figure 5

[0052] Referring to Figure 6 As shown, the method for manufacturing a GaN-based device comprises the following steps: S1, epitaxially growing a GaN-based device layer 21 on any of the GaN-based composite substrates 1, 2, 3, the GaN-based device layer 21 being close to the GaN-based substrate 11; and S2, peeling off the isolation substrate 10.

[0053] Peeling off the isolation substrate 10 can comprise melting the bonding layer 12 by heating or chemically etching the bonding layer 12.

[0054] Chemically etching the bonding layer 12 can be achieved by using an acidic solution.

[0055] Although the present application has been disclosed as above, the present application is not limited thereto. Any person skilled in the art can make various modifications and changes without departing from the spirit and scope of the present application, and the scope of protection of the present application should be defined by the scope of the claims.​

Claims

1. A GaN-based composite substrate, characterized by, The GaN-based composite substrate comprises: an isolation substrate (10), a GaN-based substrate (11), and a bonding layer (12) between the isolation substrate (10) and the GaN-based substrate (11); the material of the bonding layer (12) is at least one of aluminum, gold, silicon-gold alloy, gold-tin alloy, and copper-tin alloy; the isolation substrate (10) comprises a first isolation substrate (101) and a second isolation substrate (102), and the second isolation substrate (102) is close to the bonding layer (12); the material of the first isolation substrate (101) is single crystal silicon, and the material of the second isolation substrate (102) is aluminum oxide; and the isolation substrate (10) is used for preventing liquid from flowing downward.

2. The GaN-based composite substrate of claim 1, wherein The material of the GaN-based substrate (11) comprises GaN or AlGaN.

3. The GaN-based composite substrate according to claim 1 or 2, wherein The GaN-based substrate (11) is a single-layer structure or a laminated structure.

4. A GaN-based device, characterized by The GaN-based composite substrate comprises: the GaN-based composite substrate according to any one of claims 1 to 3, and a GaN-based device layer (21) on the GaN-based composite substrate, wherein the GaN-based device layer (21) is close to the GaN-based substrate (11).

5. A method of fabricating a GaN-based device, comprising: The GaN-based composite substrate comprises: epitaxially growing a GaN-based device layer (21) on the GaN-based composite substrate according to any one of claims 1 to 3, wherein the GaN-based device layer (21) is close to the GaN-based substrate (11); peeling off the isolation substrate (10).

6. The method of fabricating a GaN-based device of claim 5, wherein, The peeling off of the isolation substrate (10) comprises melting the bonding layer (12) by using a heating method, or chemically etching the bonding layer (12).

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