Nitride epitaxial wafer and light emitting diode

Abstract

The utility model discloses a nitride epitaxial wafer and light emitting diode. The nitride epitaxial wafer includes substrate base plate, a plurality of nitride structures and nitride layer, and a plurality of nitride structures are spaced apart on substrate base plate along the preset direction, and the nitride layer is arranged on all nitride structures, wherein, a plurality of air layers are formed between substrate base plate and nitride layer, and the air layer and nitride structure are crossed distribution on substrate base plate along the preset direction. The nitride epitaxial wafer provided by the utility model can effectively alleviate the greater stress between substrate base plate and nitride layer due to lattice mismatch and thermal mismatch by setting the air layer, avoids the crack of nitride epitaxial wafer, ensures the crystal quality and uniformity of nitride epitaxial wafer, thereby improves the performance and reliability of the device.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor material preparation, and in particular to a nitride epitaxial wafer and a light-emitting diode including the nitride epitaxial wafer. Background Technology

[0002] Group III nitrides (InN, GaN, and AlN, etc.) and their related multi-component compounds are very important wide-bandgap semiconductor materials, playing a vital role in semiconductor devices, especially optoelectronic devices.

[0003] Due to the lack of large-size homogeneous substrates, nitride materials are currently mainly grown on substrates such as sapphire, silicon nitride, or Si. Due to the differences in lattice constants and thermal expansion coefficients between these substrates and group III nitride epitaxial materials, there are very serious lattice mismatches and thermal mismatches. Group III nitride epitaxial films grown on sapphire substrates are prone to cracking due to high stress.

[0004] In existing technologies, LED devices are typically fabricated by growing light-emitting structures on sapphire substrates (i.e., sequentially stacking an n-type gallium nitride layer, a multiple quantum well layer, an electron blocking layer, and a p-type gallium nitride layer on the substrate). However, due to differences in lattice constants and coefficients of thermal expansion between the sapphire substrate and the light-emitting structure, significant stress arises from lattice and thermal mismatches. Therefore, after growing an n-type gallium nitride layer on an epitaxial wafer, a low-In-content InGaN / GaN superlattice structure is grown to alleviate the stress caused by lattice mismatch during the subsequent growth of the multiple quantum well layer. In atoms are incorporated through stress relaxation. While this method alleviates the significant stress caused by lattice and thermal mismatches to some extent, it suffers from structural complexity, high fabrication difficulty, and high cost.

[0005] This utility model solves at least one of the above problems. Summary of the Invention

[0006] To address the issue of significant stress caused by lattice and thermal mismatch between sapphire substrates and light-emitting structures due to differences in lattice constants and coefficients of thermal expansion in the prior art, the nitride epitaxial wafer of this invention effectively alleviates the significant stress caused by lattice and thermal mismatch between the substrate and the nitride layer by setting an air layer. This prevents cracks in the nitride epitaxial wafer, ensures the crystal quality and uniformity of the nitride epitaxial wafer, and thus improves the performance and reliability of the device.

[0007] A first aspect of this utility model provides a nitride epitaxial wafer, comprising: Substrate; Multiple nitride structures are spaced apart on the substrate along a predetermined direction; A nitride layer is disposed on all nitride structures; wherein, a plurality of air layers are formed between the substrate and the nitride layer; The air layer and the nitride structure are distributed intersectingly on the substrate along the preset direction.

[0008] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention involves setting multiple nitride structures on a substrate and distributing them at intervals along the width of the substrate. This creates multiple air layers with gaps between the nitride layers covering all the nitride structures and the substrate. These air layers effectively alleviate the large stress caused by lattice mismatch and thermal mismatch between the substrate and the nitride layers, preventing cracks in the nitride epitaxial wafer and ensuring the crystal quality and uniformity of the nitride epitaxial wafer, thereby improving the performance and reliability of the device.

[0009] In some feasible implementations, the nitride layer includes a plurality of first nitride epitaxial structures and a plurality of second nitride epitaxial structures, wherein the first nitride epitaxial structures are disposed one-to-one on the nitride structure; and two adjacent first nitride epitaxial structures are connected by a second nitride epitaxial structure.

[0010] In some feasible implementations, the first nitride epitaxial structure and the second nitride epitaxial structure have the same thickness; and / or, the projection of the first nitride epitaxial structure on the substrate covers the projection of the nitride structure corresponding to the first nitride epitaxial structure on the substrate; and / or, the width of the second nitride epitaxial structure is smaller than the width of the first nitride epitaxial structure; and / or, the first nitride epitaxial structure and the second nitride epitaxial structure are made of the same material.

[0011] In some feasible implementations, the gap between two adjacent first nitride epitaxial structures along the preset direction is 0.3 to 0.6 μm; and / or, the side surface of each first nitride epitaxial structure along the preset direction is a (11-20) crystal plane.

[0012] In some feasible implementations, the nitride structure and the air layer have the same thickness.

[0013] In some feasible implementations, the width of the air layer along the preset direction is greater than or equal to the width of the nitride structure along the preset direction; wherein, the preset direction is a direction perpendicular to the thickness of the nitride epitaxial wafer.

[0014] In some feasible implementations, the width of the nitride structure along the preset direction is 1 to 5 μm; the width of the air layer along the preset direction is 5 to 10 μm.

[0015] In some feasible implementations, the nitride structure is in the shape of a strip rectangle; and / or, both the nitride structure and the nitride layer are made of gallium nitride; and / or, the substrate is either a sapphire-based GaN template or a Si-based GaN template.

[0016] A second aspect of this invention provides a light-emitting diode, comprising the nitride epitaxial wafer described in the first aspect and a light-emitting structure layer disposed on the nitride epitaxial wafer.

[0017] In some feasible implementations, the light-emitting structure layer includes an N-type layer, a multiple quantum well layer, an electron blocking layer, and a P-type layer sequentially stacked on the nitride epitaxial wafer. Attached Figure Description

[0018] Figure 1 A schematic diagram of the cross-sectional structure of the nitride epitaxial wafer provided by this utility model; Figure 2 A three-dimensional structural schematic diagram of the nitride epitaxial wafer provided by this utility model; Figure 3 A schematic diagram of the cross-sectional structure of the nitride layer provided by this utility model; Figure 4 This is a schematic diagram illustrating the structural changes during the fabrication of nitride epitaxial wafers according to the present invention. Figure 5 This is a schematic diagram of the cross-sectional structure of the light-emitting diode provided by this utility model.

[0019] In the figure: 1. Substrate; 10. Growth window; 2. Nitride structure; 3. Nitride layer; 31. First nitride epitaxial structure; 32. Second nitride epitaxial structure; 4. Air layer; 5. Mask layer; 50. Mask pattern; 6. Light-emitting structure; 61. N-type layer; 62. Multiple quantum well layer; 63. Electron blocking layer; 64. P-type layer. Detailed Implementation

[0020] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make the present invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.

[0021] The terms used to describe position and direction in this utility model are illustrated with the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this utility model.

[0022] In one aspect of the embodiments of this utility model, please refer to the appendix. Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the cross-sectional structure of the nitride epitaxial wafer provided by this utility model. Figure 2 This is a three-dimensional structural diagram of the nitride epitaxial wafer provided by the present invention. The nitride epitaxial wafer includes a substrate 1, a plurality of nitride structures 2, and a nitride layer 3.

[0023] The substrate 1 is not limited in this embodiment. The substrate 1 can be either a sapphire-based GaN template or a Si-based GaN template. It is understood that a sapphire-based GaN template refers to a composite structure formed by epitaxially growing a gallium nitride (GaN) thin film on a sapphire substrate (Al2O3); a Si-based GaN template refers to a composite structure formed by epitaxially growing a gallium nitride thin film on a silicon (Si) substrate. The preferred embodiment is a sapphire-based GaN template.

[0024] Multiple nitride structures 2 are spaced apart on the substrate 1 along a predetermined direction. The material of the nitride structures 2 can be a group III nitride; in this embodiment, gallium nitride is preferred. It should be noted that the predetermined direction is perpendicular to the thickness of the nitride epitaxial wafer, and can be the length or width direction of the nitride epitaxial wafer or the substrate 1. In this embodiment, the predetermined direction is the width direction of the substrate 1.

[0025] A nitride layer 3 is disposed on all nitride structures 2, and a plurality of air layers 4 are formed between the substrate 1 and the nitride layer 3 at intervals along a predetermined direction; it can be understood that the air layers 4 and the nitride structures 2 are distributed intersectingly on the substrate 1 along the predetermined direction, and the thickness of the nitride structures 2 and the air layers 4 is the same.

[0026] Furthermore, the nitride structure 2 is rectangular in shape, which is beneficial for forming an air layer 4 with gaps between the substrate 1 and the nitride layer 3.

[0027] This invention provides a plurality of nitride structures 2 on a substrate 1, with the nitride structures 2 spaced apart along the width of the substrate 1. This creates a plurality of air layers 4 with gaps between the nitride layer 3 covering all the nitride structures 2 and the substrate 1. The air layers 4 effectively alleviate the large stress caused by lattice mismatch and thermal mismatch between the substrate 1 and the nitride layer 3, preventing cracks in the nitride epitaxial wafer and ensuring the crystal quality and uniformity of the nitride epitaxial wafer, thereby improving the performance and reliability of the device.

[0028] For some feasible implementation methods, see Appendix Figure 3 The nitride layer 3 includes a plurality of first nitride epitaxial structures 31 and a plurality of second nitride epitaxial structures 32. The first nitride epitaxial structures 31 are disposed one-to-one on the nitride structure 2. Two adjacent first nitride epitaxial structures 31 along a preset direction are connected by a second nitride epitaxial structure 32.

[0029] Furthermore, the thickness of the first nitride epitaxial structure 31 is 2–4 μm, for example, it can be 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.2 μm, 3.4 μm, 3.6 μm, 3.8 μm or 4 μm; the thickness of the nitride structure 2 is 0.5–1.5 μm, for example, it can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.5 μm.

[0030] It is worth noting that the materials of the first nitride epitaxial structure 31 and the second nitride epitaxial structure 32 are both gallium nitride. Gallium nitride can be deposited on each nitride structure 2 using a PECVD (Plasma Enhanced Chemical Vapor Deposition) device, so that a corresponding first nitride epitaxial structure 31 is formed on each nitride structure 2. The projection of the first nitride epitaxial structure 31 on the substrate 1 covers the projection of the nitride structure 2 corresponding to the first nitride epitaxial structure 31 on the substrate 1. Then, gallium nitride continues to grow on the side of each first nitride epitaxial structure 31 along a predetermined direction using a PECVD device to form multiple second nitride epitaxial structures 32. Since two adjacent first nitride epitaxial structures 31 are connected by a second nitride epitaxial structure 32, the second nitride epitaxial structure 32 connects all the first nitride epitaxial structures 31 to form a nitride layer 3.

[0031] As a preferred embodiment of this example, the first nitride epitaxial structure 31 and the second nitride epitaxial structure 32 have the same thickness, which is beneficial for all the first nitride epitaxial structures 31 to form the nitride layer 3 under the connection of the second nitride epitaxial structure 32, and ensures the surface flatness and stability of the nitride layer 3.

[0032] In a preferred embodiment of this invention, the width of the second nitride epitaxial structure 32 is smaller than the width of the first nitride epitaxial structure 31. This further facilitates the formation of the nitride layer 3 by connecting all the first nitride epitaxial structures 31 under the connection of the second nitride epitaxial structure 32. This is because the width of the second nitride epitaxial structure 32 needs to be small enough, but not zero. If the width of the second nitride epitaxial structure 32 is greater than or equal to the width of the first nitride epitaxial structure 31, it will be difficult for all the first nitride epitaxial structures 31 to be connected and formed into the nitride layer 3 by the second nitride epitaxial structure 32.

[0033] In a preferred embodiment of this invention, the gap between two adjacent first nitride epitaxial structures 31 along a preset direction is 0.3 to 0.6 μm, for example, it can be 0.3 μm, 0.4 μm, 0.5 μm or 0.6 μm; within this gap range, it is easier for the second nitride epitaxial structure 32 to connect with the two adjacent first nitride epitaxial structures 31, and further ensures the stability of the entire nitride layer 3.

[0034] It should be further noted that the width of the nitride structure 2 along the predetermined direction is 1 to 5 μm, for example, it can be 1 μm, 2 μm, 3 μm, 4 μm or 5 μm. The width of the air layer 4 along the predetermined direction is 5 to 10 μm, for example, it can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm; within this width range, the wider the air layer 4, the better the stress relief effect on the nitride layer 3 above it.

[0035] In a preferred embodiment of this invention, the side surface of each first nitride epitaxial structure 31 along a preset direction is a (11-20) crystal plane. The (11-20) crystal plane can reduce the difficulty of connecting the second nitride epitaxial structure 32 to two adjacent first nitride epitaxial structures 31, and further improve the stability of the entire nitride layer 3.

[0036] In another aspect of this invention, the above-mentioned nitride epitaxial wafer is prepared by the following steps S1-S6.

[0037] It is worth noting that the "V / III ratio" in the growth conditions of this invention refers to the molar flow ratio of group V elements to group III elements; the "rotation speed" in the growth conditions of this invention refers to the rotation speed of the substrate 1 in the reaction chamber during each growth process in the MOCVD (Metal-organic Chemical Vapor Deposition) equipment. In the MOCVD equipment, the substrate 1 is usually placed on a carrier plate, which can drive the substrate 1 to rotate.

[0038] Step S1: Refer to Figure 4 (a) A mask layer 5 made of silicon dioxide is deposited on a substrate 1 by PECVD.

[0039] The thickness of the mask layer can be 0.5 to 1.5 μm. In this embodiment, the thickness of the mask layer 5 is 1 μm.

[0040] Step S2: Refer to Figure 4 (b) The mask layer 5 is patterned through a single patterning process to obtain multiple mask patterns 50 that are spaced apart along a preset direction.

[0041] A growth window 10 exposing the substrate 1 is provided between two adjacent mask patterns 50. The width of the growth window 10 along a preset direction can be 1 to 5 μm. In this embodiment, the width of the growth window 10 is 2 μm. The width of the mask pattern 50 along the preset direction can be 5 to 10 μm. In this embodiment, the width of the mask pattern 50 is 6 μm.

[0042] Furthermore, a single patterning process may include steps such as depositing a film layer, coating photoresist, exposure, development, etching, and photoresist stripping. These are conventional techniques and will not be elaborated upon here.

[0043] Step S3: Refer to Figure 4 (c) Under the growth conditions of a growth temperature of 900–1000 °C, a growth pressure of 500–700 torr, a rotation speed of 500–800 rpm, and a V / III ratio of 1000–1500, a gallium nitride nitride structure 2 is grown in each growth window 10.

[0044] For example, the growth temperature was 950℃, the growth pressure was 600 torr, the rotation speed was 650 rpm, the V / III ratio was 1250, and the growth time was 60 min. The thickness of the nitride structure 2 was the same as the thickness of the mask layer 5, both being 1 μm.

[0045] Step S4: Refer to Figure 4Under growth conditions of 1080–1120 °C, 100–200 torr, 800–1000 rpm, and V / III of 2000–3000, a first nitride epitaxial structure 31 of gallium nitride is grown on each nitride structure 2 to obtain a first epitaxial wafer.

[0046] For example, the growth temperature was 1100℃, the growth pressure was 150 torr, the rotation speed was 900 rpm, the V / III ratio was 2500, and the growth time was 150 min.

[0047] The thickness of the first nitride epitaxial structure 31 is 3 μm, and the gap between two adjacent first nitride epitaxial structures 31 along the preset direction is 0.5 μm.

[0048] Step S5: Refer to Figure 4 (e) All mask patterns 50 within the first epitaxial wafer are etched using an etching solution to form an air layer 4.

[0049] The etching solution is hydrofluoric acid with a concentration of 49%, the volume ratio of H2O to HF is 10:1, the etching temperature is 20-30℃ (25℃ in this example), and the etching rate is 20nm / min.

[0050] Step S6: Refer to Figure 4 In (f) and (g), gallium nitride is grown on both sides of each first nitride epitaxial structure 31 along a preset direction using an MOCVD device under the growth conditions of a growth temperature of 1080–1120 °C, a growth pressure of 100–200 torr, a rotation speed of 800–1000 rpm, and a V / III ratio of 2000–3000, to form a second nitride epitaxial structure 32. This allows two adjacent first nitride epitaxial structures 31 along the preset direction to be connected through the second nitride epitaxial structure 32, until all first nitride epitaxial structures 31 are merged to form a nitride layer 3 located on the air layer 4, thus obtaining a nitride epitaxial wafer.

[0051] For example, the growth temperature was 1100℃, the growth pressure was 150 torr, the rotation speed was 900 rpm, the V / II was 2500, and the growth time was 30 min.

[0052] The thickness of the second nitride epitaxial structure 32 is the same as that of the first nitride epitaxial structure 31, both being 3 μm.

[0053] In another aspect of this utility model embodiment, please refer to Figure 5 , Figure 5This is a schematic cross-sectional view of the light-emitting diode provided by the present invention. The light-emitting diode includes the above-mentioned nitride epitaxial wafer and a light-emitting structure layer 6 disposed on the nitride epitaxial wafer.

[0054] The light-emitting structure layer 6 includes an N-type layer 61, a multiple quantum well layer 62, an electron blocking layer 63, and a P-type layer 64, which are sequentially stacked on the nitride layer 3 of the nitride epitaxial wafer.

[0055] For example, the N-type layer 61 can be an n-GaN layer; the P-type layer 64 can be a p-GaN layer.

[0056] This invention utilizes the air layer 4 structure within the nitride epitaxial wafer to better relax stress and simplifies the superlattice structure, allowing direct growth of the n-GaN layer, multiple quantum well layer 62, electron blocking layer 63, and p-GaN layer. Furthermore, the presence of the air layer 4 allows the high junction temperature generated by the LED device during operation to be released, contributing to improved thermal stability of the LED device's performance, stable emission wavelength, and extended lifespan.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and alterations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A nitride epitaxial wafer, characterized in that, include: Substrate; Multiple nitride structures are spaced apart on the substrate along a predetermined direction; A nitride layer is disposed on all nitride structures; wherein, a plurality of air layers are formed between the substrate and the nitride layer; The air layer and the nitride structure are distributed intersectingly on the substrate along the preset direction.

2. The nitride epitaxial wafer according to claim 1, characterized in that, The nitride layer includes a plurality of first nitride epitaxial structures and a plurality of second nitride epitaxial structures, wherein the first nitride epitaxial structures are disposed one-to-one on the nitride structure; two adjacent first nitride epitaxial structures are connected by a second nitride epitaxial structure.

3. The nitride epitaxial wafer according to claim 2, characterized in that, The first nitride epitaxial structure has the same thickness as the second nitride epitaxial structure; And / or, the width of the second nitride epitaxial structure is smaller than the width of the first nitride epitaxial structure.

4. The nitride epitaxial wafer according to claim 2, characterized in that, The projection of the first nitride epitaxial structure on the substrate covers the projection of the nitride structure corresponding to the first nitride epitaxial structure on the substrate. And / or, the first nitride epitaxial structure and the second nitride epitaxial structure are made of the same material.

5. The nitride epitaxial wafer according to claim 2, characterized in that, The gap between two adjacent first nitride epitaxial structures along the preset direction is 0.3 to 0.6 μm; And / or, the side surface of each of the first nitride epitaxial structures along the preset direction is a (11-20) crystal plane.

6. The nitride epitaxial wafer according to claim 1, characterized in that, The nitride structure and the air layer have the same thickness.

7. The nitride epitaxial wafer according to claim 1, characterized in that, The width of the air layer along the preset direction is greater than or equal to the width of the nitride structure along the preset direction; The preset direction is a direction perpendicular to the thickness of the nitride epitaxial wafer.

8. The nitride epitaxial wafer according to claim 7, characterized in that, The width of the nitride structure along the preset direction is 1 to 5 μm; The width of the air layer along the preset direction is 5 to 10 μm.

9. The nitride epitaxial wafer according to claim 1, characterized in that, The nitride structure is in the shape of a strip-shaped rectangle; And / or, the materials of the nitride structure and the nitride layer are both gallium nitride; And / or, the substrate is either a sapphire-based GaN template or a Si-based GaN template.

10. A light-emitting diode, characterized in that, It includes the nitride epitaxial wafer as described in any one of claims 1-9 and a light-emitting structure layer disposed on the nitride epitaxial wafer.

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