LED device and preparation method thereof

Abstract

The invention discloses an LED device and a preparation method thereof, and the preparation method comprises the steps: forming an epitaxial structure on a substrate, and obtaining a nitride epitaxial wafer; the epitaxial structure comprises a plurality of first nitride structures and nitride layers covering all the first nitride structures, a plurality of air layers arranged at intervals in the preset direction are arranged between the substrate and the nitride layers, and the air layers and the first nitride structures are alternately distributed on the substrate; forming a light-emitting structure layer on the nitride layer of the nitride epitaxial wafer to obtain a first LED epitaxial structure; removing the first nitride structure of the first LED epitaxial structure along the air layer, and separating the substrate from the nitride layer to obtain a second LED epitaxial structure; the second LED epitaxial structure comprises a nitride layer and a light-emitting structure layer which are stacked in sequence; and forming an N-type electrode on the nitride layer of the second LED epitaxial structure to obtain the LED device. The nitride layer and the substrate are separated through the air layer, separation damage is reduced, lossless separation can be achieved, and the performance of the LED device is ensured.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material preparation, and in particular to an LED device and its preparation method. Background Technology

[0002] LED devices are classified into upright, flip-chip, and vertical structures. Among them, vertical LED chips have attracted widespread attention due to their high thermal resistance, good heat dissipation, and ability to avoid current congestion. In fabricating vertical LED devices, the substrate used in the LED epitaxial wafer fabrication needs to be peeled off to separate the substrate from the epitaxial layer. Common peeling methods include chemical etching or laser ablation, which can create a large amount of damage at the separation interface, thus affecting the performance of the LED device. Summary of the Invention

[0003] To address the problem that existing technologies for fabricating vertical LED devices often employ chemical etching or laser ablation to separate the substrate from the epitaxial layer, resulting in a large amount of damage at the separation interface and thus affecting LED device performance, this invention provides a method for fabricating LED devices. By forming an air layer on the epitaxial structure and utilizing this air layer to separate the nitride layer and substrate, the separation damage to the nitride layer is reduced, facilitating non-destructive separation and ensuring the performance of the LED device.

[0004] A first aspect of the present invention provides a method for fabricating an LED device, comprising the following steps: An epitaxial structure is formed on a substrate to obtain a nitride epitaxial wafer; wherein, the epitaxial structure includes a plurality of first nitride structures and a nitride layer covering all the first nitride structures, and a plurality of air layers are provided between the substrate and the nitride layer along a predetermined direction, and the air layers and the first nitride structures are alternately distributed on the substrate. A light-emitting structure layer is formed on the nitride layer of the nitride epitaxial wafer to obtain a first LED epitaxial structure; The first nitride structure in the first LED epitaxial structure is removed along the air layer to separate the substrate and the nitride layer, thereby obtaining a second LED epitaxial structure; wherein, the second LED epitaxial structure includes at least the nitride layer and the light-emitting structure layer stacked sequentially; An N-type electrode is formed on the nitride layer in the second LED epitaxial structure to obtain an LED device.

[0005] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention forms an epitaxial structure on a substrate, creating multiple first nitride structures spaced apart along the width of the substrate. This results in multiple air layers, alternating with the first nitride structures, being formed between the nitride layer covering all the first nitride structures and the substrate. By setting these air layers, the significant stress caused by lattice and thermal mismatch between the substrate and the gallium nitride epitaxial layer can be effectively alleviated, enabling the fabrication of low-stress nitride epitaxial wafers. This avoids cracking in the nitride epitaxial wafers, improves the crystal quality and uniformity of the nitride epitaxial wafers, and thus enhances the performance and reliability of the device. Separating the nitride layer and the substrate by removing the first nitride structures along the air layers is not limited by the size of the substrate, reduces separation damage to the nitride layer, and facilitates non-destructive separation, ensuring the performance of the LED device.

[0006] In some possible implementations, the thickness of the nitride layer is greater than the width of the first nitride structure; and / or, the material of the nitride layer is the same as the material of the first nitride structure.

[0007] In some possible implementations, forming an epitaxial structure on a substrate to obtain a nitride epitaxial wafer includes: Multiple mask patterns are formed on the substrate at intervals along a predetermined direction; wherein, a growth window exposing the substrate is provided between two adjacent mask patterns; The first nitride structure comprising the target nitride is formed within each growth window; Under growth conditions of 1080–1120 °C, 100–200 torr, 800–1000 rpm, and V / III ratio of 2000–3000, a second nitride structure including the target nitride is formed on each of the first nitride structures to obtain an initial epitaxial wafer. All the mask patterns in the initial epitaxial wafer are removed so that at least one side of each second nitride structure forms an air layer on the substrate. Under growth conditions of 1080-1120°C, 100-200 torr, 800-1000 rpm, and V / III of 2000-3000, the target nitride is grown on both sides of each second nitride structure along the preset direction so that all the second nitride structures are merged to form a nitride layer on all the air layers, thus obtaining the nitride epitaxial wafer.

[0008] In some possible implementations, removing the first nitride structure along the air layer includes: At a deposition temperature of 200–350°C, a protective layer of SiO2 material with a thickness of 200 nm is formed on the side of the first LED epitaxial structure, exposing at least part of the air layer. The first nitride structure is etched along the exposed air layer at a temperature of 80–120°C.

[0009] In some possible implementations, the first LED epitaxial structure further includes a conductive layer and a heat-dissipating bonding structure stacked on the light-emitting structure layer. After the light-emitting structure layer is formed on the nitride layer of the nitride epitaxial wafer, the fabrication method further includes: Under the conditions of working gas pressure of 0.3 to 1 Pa and radio frequency power of 50 to 200 W, a conductive layer with ITO material and a thickness of 100 to 200 nm is sputtered on the light-emitting structure layer; A heat-dissipating bonding structure is formed on the conductive layer; The second LED epitaxial structure further includes the conductive layer and the heat dissipation bonding structure on the light-emitting structure layer stacked sequentially.

[0010] In some possible implementations, forming an N-type electrode on the nitride layer in the second LED epitaxial structure includes: The separation surface of the nitride layer in the second LED epitaxial structure is flattened to make the separation surface of the nitride layer a flat surface; The N-type electrode is deposited on the smooth surface of the nitride layer in the second LED epitaxial structure.

[0011] In some possible implementations, before removing the first nitride structure in the first LED epitaxial structure along the air layer, the preparation method further includes: forming a bonding layer with a thickness of 3 to 5 μm on the heat dissipation bonding structure to bond a temporary carrier to the heat dissipation bonding structure through the bonding layer.

[0012] In some feasible implementations, the heat dissipation bonding structure includes at least one metal layer stacked on the conductive layer; forming the metal layer includes: A metal layer of Ti / Au material with a thickness of 50–200 nm is deposited on the conductive layer.

[0013] In some possible implementations, after forming an N-type electrode on the nitride layer in the second LED epitaxial structure, the fabrication method further includes: An N-type ohmic contact layer is formed on the side of the N-type electrode away from the nitride layer; The N-type contact layer is bonded to the target carrier; Remove the temporary carrier, the protective layer, and the heat dissipation bonding structure to obtain the LED device.

[0014] In a second aspect, the present invention provides an LED device prepared by any of the above-described preparation methods. Attached Figure Description

[0015] Figure 1 A flowchart illustrating the overall steps of the LED device fabrication method provided by this invention; Figure 2 This invention provides a schematic diagram of the structural changes of an LED device during its fabrication process; Figure 3 A schematic diagram illustrating the structural changes of the nitride epitaxial wafer provided by this invention during the preparation process; Figure 4 for Figure 1 The illustrated embodiment shows a schematic diagram of the first LED epitaxial structure in step S3.

[0016] In the figure: 1. Substrate; 10. Growth window; 2. First nitride structure; 20. Mask pattern; 3. Nitride layer; 30. Second nitride structure; 4. Air layer; 5. Mask layer; 50. Mask pattern; 6. Light-emitting structure layer; 61. n-type gallium nitride layer; 62. Multiple quantum well layer; 63. Electron blocking layer; 64. p-type gallium nitride layer; 7. Protective layer; 8. Conductive layer; 9. Heat dissipation bonding structure; 11. Temporary carrier; 12. N-type electrode; 13. N-type ohmic contact layer; 14. Target carrier. Detailed Implementation

[0017] 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, they are provided to make the 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.

[0018] The terms used to express position and direction in this invention are illustrated with reference to the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this invention.

[0019] 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 in the reaction chamber during each growth process in the MOCVD (Metal-organic Chemical Vapor Deposition) equipment. In the MOCVD equipment, the substrate is usually placed on a carrier plate, which can drive the substrate to rotate.

[0020] In one aspect, the present invention provides a method for fabricating an LED device, such as... Figure 1 and 2 As shown, it includes the following steps S1-S4.

[0021] Step S1: An epitaxial structure is formed on the substrate 1 to obtain a nitride epitaxial wafer.

[0022] The epitaxial structure includes multiple first nitride structures 2 and a nitride layer 3 covering all the first nitride structures 2. Multiple air layers 4 are spaced apart between the substrate 1 and the nitride layer 3 along a predetermined direction. The air layers 4 and the first nitride structures 2 are alternately distributed on the substrate 1. The predetermined direction can be the length direction or the width direction of the substrate 1; in this embodiment of the invention, the width direction is preferred.

[0023] The present invention does not limit the substrate 1, which 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 of the present invention is a sapphire-based GaN template.

[0024] Furthermore, the first nitride structure 2 and the nitride layer 3 are made of the same material, both being group III nitrides. In this embodiment of the invention, gallium nitride is preferably used as the group III nitride.

[0025] By forming an epitaxial structure on a substrate 1, a nitride epitaxial wafer is obtained. This not only forms multiple first nitride structures 2 spaced apart along the width direction on the substrate 1, but also forms multiple air layers 4 that alternate with the first nitride structures 2 between the nitride layer 3 covering all the first nitride structures 2 and the substrate 1. The air layers 4 can effectively alleviate the large stress caused by lattice mismatch and thermal mismatch between the substrate 1 and the nitride layer 3.

[0026] This is because traditional nitride epitaxial wafers are formed by a rigid connection between the epitaxial layer and the substrate at the atomic level. Stress cannot be escaped and must be borne solely by the epitaxial layer itself. However, this invention fundamentally changes this connection method by introducing an air layer 4. Even with some residual stress, the nitride layer 3 structure above the air layer 4 acts like a suspended thin film or bridge, possessing a certain degree of elasticity and flexibility. It can adapt to and release localized stress through slight bending or deformation, unlike a rigid connection which can only cope by generating defects or fractures. Therefore, the air layer 4 can prevent cracks in the nitride epitaxial wafer, improve the crystal quality and uniformity of the nitride epitaxial wafer, and thus further enhance the performance and reliability of devices fabricated using nitride epitaxial wafers.

[0027] As one possible implementation of step S1, such as Figure 3 As shown, an epitaxial structure is formed on a substrate 1 to obtain a nitride epitaxial wafer, including steps S11-S15.

[0028] Step S11: Form a plurality of mask patterns 50 that are spaced apart along a preset direction on the substrate 1.

[0029] It should be noted that a growth window 10 exposing the substrate 1 is provided between two adjacent mask patterns 50 along a preset direction, thereby forming a plurality of spaced growth windows 10 on the substrate 1 through the mask patterns 50. In this embodiment of the invention, both the growth window 10 and the mask pattern 50 can be rectangular in shape, and the width of the growth window 10 along the preset direction can be less than or equal to the width of the mask pattern 50 along the preset direction.

[0030] Furthermore, in this embodiment of the invention, the width of the growth window 10 along the preset 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 mask pattern 50 along the preset direction is 5 to 10 μm, for example, it can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm.

[0031] As one implementation of step S11, a plurality of mask patterns 50 are formed on the substrate 1 at intervals along a preset direction, including steps S111-S112.

[0032] Step S111: Form a mask layer 5 on the substrate 1. For example... Figure 3 (a)

[0033] In this embodiment of the invention, a mask layer 5 with a thickness of 0.5–1.5 μm is deposited on a sapphire-based GaN template using PECVD (Plasma Enhanced Chemical Vapor Deposition). For example, the thickness of the mask layer 5 can be 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, or 1.5 μm.

[0034] Optionally, the material of the mask layer 5 is either silicon dioxide or silicon nitride, and silicon dioxide is preferred in this embodiment of the invention.

[0035] Step S112: Pattern the mask layer 5 to obtain multiple mask patterns 50 spaced apart along a preset direction. For example... Figure 3 (b)

[0036] In this embodiment of the invention, a single patterning process can be used to pattern the mask layer 5 to form multiple mask patterns 50 spaced apart along a predetermined direction on the substrate 1. The mask patterns 50 are located on the substrate 1 and expose the substrate 1, dividing the substrate 1 into multiple spaced growth windows 10. Further, this single patterning process may include steps such as depositing a film layer, coating photoresist, exposure, development, etching, and photoresist stripping. This patterning process uses commonly used existing processes, which will not be described in detail here.

[0037] Step S12: Form a first nitride structure 2 comprising the target nitride within each growth window 10. For example... Figure 3 (c)

[0038] The target nitride can be a group III nitride, and gallium nitride is a preferred group III nitride in this embodiment of the invention.

[0039] Furthermore, the side surface of the growth window 10 away from the substrate 1 is flush with the side surface of the first nitride structure 2 away from the substrate 1, providing the necessary growth space for the subsequent second nitride structure 30.

[0040] As an optional implementation of step S12, a first nitride structure 2 including the target nitride is formed in each growth window 10, including: growing the target nitride in each growth window 10 using an MOCVD device under 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 of 1000-1500, so as to form a first nitride structure 2 on the substrate 1 with the same thickness as the mask layer 5.

[0041] Exemplarily, the growth temperature can be 910 °C, 920 °C, 930 °C, 940 °C, 950 °C, 960 °C, 970 °C, 980 °C, 990 °C or 1000 °C; the growth pressure can be 500 torr, 525 torr, 550 torr, 575 torr, 600 torr, 625 torr, 650 torr, 675 torr or 700 torr; the rotation speed can be 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm or 800 rpm; the V / III ratio can be 1100, 1150, 1200, 1250, 1300, 1350, 1400, 1450 or 1500.

[0042] It should be noted that the inventors found that the growth time of the first nitride structure 2 is related to the width of the growth window 10. Therefore, based on the width of the growth window, the growth time of the first nitride structure 2 can be controlled. Exemplarily, when the width of the growth window 10 is 2 μm, the growth time is 10 min.

[0043] Under the above growth conditions, the target nitride (i.e., GaN) selectively grows into the first nitride structure 2 in the growth window 10, and the surface of the growth window 10 away from the substrate 1 is flush with the surface of the first nitride structure 2 away from the substrate 1.

[0044] Step S13: 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 of 2000 - 3000, a second nitride structure 30 including the target nitride is grown on each first nitride structure 2 by means of a MOCVD device to obtain an initial epitaxial wafer. As Figure 3 in (d).

[0045] For example, the growth temperature can be 1080℃, 1085℃, 1090℃, 1095℃, 1100℃, 1105℃, 1110℃, 1115℃, or 1120℃; the growth pressure can be 100 torr, 110 torr, 120 torr, 130 torr, 140 torr, 150 torr, 160 torr, 170 torr, 180 torr, 190 torr, or 200 torr; the rotation speed can be 800 rpm, 820 rpm, 840 rpm, 860 rpm, 880 rpm, 900 rpm, 920 rpm, 940 rpm, 960 rpm, or 980 rpm. rpm or 1000rpm; V / III ratio can be 2000, 2100, 2200, 2400, 2500, 2600, 2700, 2800, 2900 or 3000; the thickness of the second nitride structure 30 can be 2μm, 2.2μm, 2.4μm, 2.6μm, 2.8μm, 3μm, 3.2μm, 3.4μm, 3.6μm, 3.8μm or 4μm.

[0046] Under these growth conditions, the target nitride (GaN) continues to selectively grow on the first nitride structure 2 within the growth window 10 region, forming a second nitride structure 30. Because GaN exhibits strong lateral growth capability but weak three-dimensional growth capability under these conditions, each second nitride structure 30 extends along a predetermined direction onto portions of the mask pattern 50 on both sides of the corresponding first nitride structure 2, creating a gap between adjacent second nitride structures 30 along the predetermined direction. It can be understood that this gap is smaller than the width of the mask pattern 50.

[0047] It should be noted that, within the growth conditions of step S13, the gap between two adjacent second nitride structures 30 along the preset direction can be controlled to be 0.3 to 0.6 μm, for example, 0.3 μm, 0.4 μm, 0.5 μm or 0.6 μm; this gap range can reduce the difficulty of merging the second nitride structures 30 in step S15, making it easier for all the second nitride structures 30 to merge, which helps to form a high-quality nitride layer 3 and improve the crystal quality of the nitride epitaxial wafer; it should be further noted that, within the growth conditions of step S13, the side of the second nitride structure 30 along the preset direction can be made to be a (11-20) crystal plane, which further reduces the difficulty of merging the second nitride structures 30, making it easier for all the second nitride structures 30 to merge.

[0048] Furthermore, the inventors discovered that the growth time of the second nitride structure 30 is related to the width of the mask pattern 50, so the growth time of the second nitride structure 30 can be controlled based on the width of the mask pattern 50; for example, when the width of the mask pattern 50 is 6 μm, the growth time is 50 min.

[0049] Step S14: Remove all mask patterns 50 within the initial epitaxial wafer to form an air layer 4 on the substrate 1 on at least one side of each first nitride structure 2. Figure 3 (e)

[0050] As an optional implementation of step S14, removing all mask patterns 50 within the initial epitaxial wafer includes: immersing the initial epitaxial wafer in an etching solution so that the etching solution performs wet etching on all mask patterns 50 within the initial epitaxial wafer along the gaps.

[0051] In this embodiment of the invention, the etching solution can be a solution that can corrode silicon dioxide, such as HF (hydrofluoric acid). Specifically, the concentration of hydrofluoric acid is 47%–51%, the volume ratio of H2O to HF in the hydrofluoric acid is (9:1)–(11:1), the etching temperature is 20–30°C, and the etching rate is 20–50 nm / min. For example, the concentration of hydrofluoric acid can be 47%, 48%, 49%, 50%, or 51%, the volume ratio of H2O to HF in the hydrofluoric acid can be 9:1, 10:1, or 11:1, the etching temperature can be 20°C, 22°C, 25°C, 28°C, or 30°C, and the etching rate can be 20 nm / min, 25 nm / min, 30 nm / min, 35 nm / min, 40 nm / min, 45 nm / min, or 50 nm / min.

[0052] Under these etching conditions, over-etching of the mask pattern 50 can be achieved, so that all mask patterns 50 can be etched cleanly, preventing the air layer 4 from being too thin and affecting its function of relieving large stresses in the nitride epitaxial wafer.

[0053] In some alternative implementations, the initial epitaxial wafer after etching can be cleaned. For example, the initial epitaxial wafer after etching can be cleaned by immersion in deionized water and ultrasonic cleaning to remove contaminants from the wet etching process described above.

[0054] Step S15: Under growth conditions of 1080–1120℃, growth pressure of 100–200 torr, rotation speed of 800–1000 rpm, and V / III ratio of 2000–3000, target nitrides are grown on both sides of each second nitride structure 30 along a predetermined direction, so that all second nitride structures 30 are merged to form a nitride layer 3 located on all air layers 4, thus obtaining a nitride epitaxial wafer. Figure 3 (f).

[0055] For example, the growth temperature can be 1080℃, 1085℃, 1090℃, 1095℃, 1100℃, 1105℃, 1110℃, 1115℃, or 1120℃; the growth pressure can be 100 torr, 110 torr, 120 torr, 130 torr, 140 torr, 150 torr, 160 torr, 170 torr, 180 torr, 190 torr, or 200 torr; the rotation speed can be 800 rpm, 820 rpm, 840 rpm, 860 rpm, 880 rpm, 900 rpm, 920 rpm, 940 rpm, 960 rpm, or 980 rpm. rpm or 1000rpm; V / III ratio can be 2000, 2100, 2200, 2400, 2500, 2600, 2700, 2800, 2900 or 3000.

[0056] Because the gap width is small, only 0.3 to 0.6 μm, under this growth condition, two adjacent second nitride structures 30 along the preset direction can easily merge through the target nitride until all the second nitride structures 30 are connected to form a nitride layer 3. This allows the air layer 4 to be periodically distributed between the nitride layer 3 and the substrate 1, effectively alleviating the large stress caused by lattice mismatch and thermal mismatch between the substrate 1 and the nitride layer 3.

[0057] Further research by the inventors revealed that the widths of the growth window 10 and the mask pattern 50 are limited by the migration ability of Ga atoms during GaN growth in the MOCVD equipment and the difficulty of merging the final thin film. If the mask pattern 50 is too wide (greater than 10 μm), the second nitride structure 30 will be difficult to merge; simultaneously, the mask pattern 50 cannot be too narrow (less than 5 μm), as this would affect the etching effect of the etching solution on the mask pattern 50, posing a risk of not being able to effectively remove all mask patterns 50. In the process of preparing a nitride epitaxial wafer by forming an epitaxial structure on the substrate 1, the substrate 1 is divided into multiple spaced growth windows 10 by the mask pattern 50. Therefore, the nitride epitaxial structure only needs to be formed in the growth window 10 region on the substrate 1, without etching the entire nitride film layer formed on the substrate, thus obtaining the nitride epitaxial wafer. Compared to existing technologies, this avoids damage to the sidewalls of the formed nitride epitaxial structure, ensuring the performance of the nitride epitaxial wafer. Furthermore, etching away the mask pattern 50 can provide the necessary space for the subsequent formation of the air layer 4.

[0058] Step S2: A light-emitting structure layer 6 is sequentially formed on the nitride layer 3 of the nitride epitaxial wafer to obtain the first LED epitaxial structure. The structure of the first LED epitaxial structure is as follows: Figure 4 As shown.

[0059] For example, the light-emitting structure layer 6 includes an n-type gallium nitride layer 61, a multiple quantum well layer 62, an electron blocking layer 63, and a p-type gallium nitride layer 64, which are grown sequentially. It is worth noting that the growth process of the n-type gallium nitride layer 61, the multiple quantum well layer 62, the electron blocking layer 63, and the p-type gallium nitride layer 64 is a commonly used existing process, which will not be described in detail here.

[0060] Furthermore, such as Figure 2 As shown in (a), the first LED epitaxial structure further includes a conductive layer 8 and a heat dissipation bonding structure 9 stacked on the light-emitting structure layer 6. After the light-emitting structure layer 6 is formed on the nitride layer 3 of the nitride epitaxial wafer, the above preparation method further includes steps S20a-S20b.

[0061] Step S20a: Under the conditions of working gas pressure of 0.3 to 1 Pa and radio frequency power of 50 to 200 W, a conductive layer 8 with ITO (indium tin oxide) material and a thickness of 100 to 200 nm is sputtered on the light-emitting structure layer 6.

[0062] A conductive layer 8 can be formed on the light-emitting structure layer 6 by magnetron sputtering. For example, the working pressure of magnetron sputtering can be 0.3 Pa, 0.4 Pa, 0.5 Pa, 0.6 Pa, 0.7 Pa, 0.8 Pa, 0.9 Pa, or 1 Pa; the RF power of magnetron sputtering can be 50 W, 70 W, 90 W, 120 W, 140 W, 160 W, 180 W, or 200 W; and the thickness of the conductive layer 8 can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, or 200 nm.

[0063] It should be noted that, at this point, the second LED epitaxial structure also includes a conductive layer 8 and a heat dissipation bonding structure 9 stacked on the light-emitting structure layer 6. The conductive layer 8 is configured as the P electrode on the light-emitting structure layer 6. The ITO conductive layer 8 has a transmittance of 85% to 95% in the visible light band (380–780 nm), while its resistivity is as low as 10⁻⁻⁻⁶. 4 With a strength on the order of Ω·cm, it achieves a synergistic optimization of optical transparency and electrical conductivity. This characteristic makes it the preferred material for transparent electrodes in devices such as LEDs, ensuring both display clarity and efficient conduction of electrical signals. At the same time, ITO material has corrosion resistance and oxidation resistance, maintaining stable performance during long-term use.

[0064] Step S20b: A heat-dissipating bonding structure 9 is formed on the conductive layer 8. It should be noted that the heat-dissipating bonding structure 9 can be used both as part of the bonding interface and as a heat dissipation channel with a supporting function.

[0065] Furthermore, the heat dissipation bonding structure 9 includes at least one metal layer stacked on the conductive layer 8. Forming the metal layer includes depositing at least one metal layer with Ti / Au material and a thickness of 50 to 200 nm on the conductive layer 8 to form the heat dissipation bonding structure 9.

[0066] At least one metal layer of Ti / Au material can be deposited on the conductive layer 8 using a metal evaporation process. For example, the thickness of the metal layer can be 50 nm, 70 nm, 90 nm, 110 nm, 130 nm, 150 nm, 170 nm, 190 nm, or 200 nm. The metal evaporation process uses existing commonly used processes and will not be described in detail here.

[0067] Step S3: Remove the first nitride structure 2 in the first LED epitaxial structure along the air layer 4 to separate the substrate 1 and the nitride layer 3, thereby obtaining the second LED epitaxial structure.

[0068] The second LED epitaxial structure includes at least a nitride layer 1 and a light-emitting structure layer 6 stacked sequentially. As one embodiment that can be implemented in step S3, removing the first nitride structure 2 from the first LED epitaxial structure along the air layer 4 includes steps S31-S32.

[0069] Step S31: Under a deposition temperature of 200–350°C, a protective layer 7 of SiO2 material with a thickness of 150–200 nm is deposited on the side of the first LED epitaxial structure, exposing at least part of the air layer 4. Figure 2 As shown in (a).

[0070] This invention utilizes ALD (Atomic Layer Deposition) to form the protective layer 7 because ALD has better density than PECVD (Plasma Enhanced Chemical Vapor Deposition) deposited protective layer 7. Furthermore, ALD deposition of the protective layer 7 allows for relatively uniform deposition on the sides of the first LED epitaxial structure, which is generally difficult to achieve with PECVD. For example, the deposition temperature can be 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 310℃, 320℃, 330℃, 340℃, or 350℃; the thickness of the protective layer 7 can be 150mm, 160mm, 170mm, 180mm, 190mm, or 200mm.

[0071] It should be noted that, as Figure 2 As shown in (a). The protective layer 7 can also extend to the top surface of the first LED epitaxial structure, and the protective layer 7 on the top surface can then be removed by etching with an HF solution.

[0072] By depositing a protective layer 7 on the side of the first LED epitaxial structure, it is helpful to protect the side of the first LED epitaxial structure during the removal of the first nitride structure 2 and prevent damage to it.

[0073] Step S33: Under conditions of 80–120°C, etch the first nitride structure 2 along the exposed air layer 4. (e.g.) Figure 2 As shown in (c), As one implementation of step S32, the first LED epitaxial structure is immersed in an etching solution at a temperature of 80-120°C to etch the first nitride structure 2.

[0074] Since the material of the first nitride structure 2 is gallium nitride, a 56% KOH solution can be used as the etching solution to etch the gallium nitride. For example, the etching temperature can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, or 120℃.

[0075] Because the side surface of the first LED epitaxial structure (except for the air layer 4) is covered by the protective layer 7, the KOH solution will enter the first LED epitaxial structure through the air layer 4 and contact the interface between the substrate 1 and the epitaxial structure to etch the first nitride structure 2.

[0076] During the research and development process, the inventors discovered that the immersion time of the first LED epitaxial structure in the etching solution is related to the width of the first nitride structure 2 along a preset direction.

[0077] It is worth noting that because the air layer 4 is covered by the nitride layer 3, the nitride layer 3 may also be corroded by the KOH solution, further increasing the thickness of the air layer 4. Therefore, to avoid affecting the use of the subsequently fabricated LED device, the thickness of the nitride layer 3 needs to be greater than the width of the first nitride structure 2. This ensures that the first nitride structure 2 will not affect the light-emitting structure layer 6 in the first LED epitaxial structure after complete corrosion. Generally, the separation of the substrate 1 and the nitride layer 3 can be observed directly with the naked eye, indicating that the separation is complete.

[0078] Step S4: An N-type electrode 12 is formed on the nitride layer 3 in the second LED epitaxial structure to obtain the LED device.

[0079] As one implementation of step S4, forming an N-type electrode 12 on the nitride layer 3 in the second LED epitaxial structure includes steps S41-S42.

[0080] Step S41: The separation surface of the nitride layer 3 in the second LED epitaxial structure is planarized to make it a flat surface. The planarization process includes repairing and cleaning the separation surface to ensure it can serve as a good growth interface. The repair and cleaning of the separation surface uses existing common processes, which will not be described in detail here. Figure 2 As shown in (d).

[0081] Step S42: Deposit an N-type electrode 12 on the smooth surface of the nitride layer 3 in the second LED epitaxial structure. (e.g.) Figure 2 As shown in (e).

[0082] The smooth surface of the nitride layer 3 provides a good growth base for the layered N-type electrode 12. The deposition of the N-type electrode 12 adopts existing commonly used processes, which will not be described in detail here.

[0083] Using the above-described fabrication method, an epitaxial structure is formed on a substrate 1, resulting in multiple first nitride structures 2 spaced apart along the width of the substrate 1. This creates multiple air layers 4, alternating with the first nitride structures 2, between the nitride layer 3 covering all the first nitride structures 2 and the substrate 1. The air layers 4 effectively alleviate the significant stress caused by lattice and thermal mismatch between the substrate 1 and the nitride layer 3, enabling the fabrication of a low-stress nitride epitaxial wafer. This avoids cracking in the nitride epitaxial wafer, improves its crystal quality and uniformity, and thus enhances the device's performance and reliability. Separating the nitride layer 3 and the substrate 1 by removing the first nitride structures 2 along the air layers 4 is not limited by the size of the substrate 1, reduces separation damage to the nitride layer 3, and facilitates non-destructive separation, ensuring the performance of the LED device.

[0084] In a preferred embodiment of the present invention, after forming an N-type electrode 12 on the nitride layer 3 in the second LED epitaxial structure, the preparation method further includes steps S43-S45. Figure 2 (f) and Figure 2 As shown in (g).

[0085] Step S43: Form an N-type ohmic contact layer 13 on the side of the N-type electrode 12 away from the nitride layer 3, such as... Figure 2 As shown in (f), an N-type ohmic contact layer 13 can be deposited on the side of the N-type electrode 12 away from the nitride layer 3 using a metal vapor deposition process. The material of the N-type ohmic contact layer 13 is Ti / Al / Ti / Au, Ti / Al / Ni / Au, or V / Al / Ti / Au. The metal vapor deposition process uses existing commonly used processes, which will not be described in detail here.

[0086] Step S44: Bond the N-type contact layer 13 to the target carrier 14, such as... Figure 2 As shown in (f).

[0087] The target carrier 14 can be a substrate 1. The N-type contact layer 13 can be bonded to the substrate 1 by electroplating. The electroplating process adopts the commonly used process and will not be described in detail here.

[0088] Step S45: Remove the temporary carrier 11, protective layer 7, and heat dissipation bonding structure 9, as follows Figure 2 As shown in (g).

[0089] Removing the temporary carrier 11, the protective layer 7, and the heat dissipation bonding structure 9 includes steps S451-S453.

[0090] Step S451: Dissociate the bonding layer to separate the temporary carrier 11 from the heat dissipation bonding structure 9. For example, the bonding layer made of PMMA can be dissociated by a pyrolysis process. The pyrolysis process uses existing commonly used processes, which will not be described in detail here.

[0091] Step S452: Remove heat dissipation bonding structure 9.

[0092] For example, the heat dissipation bonding structure 9 can be peeled off from the conductive layer 8 by mechanical peeling or laser peeling. Mechanical peeling or laser peeling uses existing common processes, which will not be elaborated here.

[0093] Step S453: Remove the protective layer 7.

[0094] For example, the protective layer 7, which is made of SiO2, can be removed by HF solution. The HF solution can be configured according to actual needs, which will not be elaborated here.

[0095] The present invention will be further described below with reference to specific embodiments. Example 1

[0096] This embodiment provides a method for fabricating an LED device, including the following steps S1-S7.

[0097] Step S1: An epitaxial structure is formed on a substrate to obtain a nitride epitaxial wafer. Forming an epitaxial structure on a substrate to obtain a nitride epitaxial wafer includes steps S11-S16.

[0098] Step S11: A mask layer with a thickness of 0.5 μm and made of silicon dioxide is deposited on a substrate (sapphire-based GaN template) by PECVD. Step S12: The mask layer is patterned to obtain multiple mask patterns that are spaced apart along a preset direction.

[0099] The preset direction is the width direction of the sapphire-based GaN template. A growth window exposing the substrate is provided between two adjacent mask patterns. The width of the growth window 10 along the preset direction is 1μm, and the width of the mask pattern along the preset direction is 5μm.

[0100] Step S13: Under the growth conditions of 900℃, 500 torr, 500 rpm, and V / III = 1000, a first nitride structure with gallium nitride and a thickness of 0.5 μm is grown in each growth window. The growth time is 25 min.

[0101] Step S14: Under the growth conditions of 1080℃, 100 torr, 800 rpm, and V / III of 2000, a second gallium nitride structure with a thickness of 2 μm is grown on each first nitride structure to obtain an initial epitaxial wafer. The growth time is 120 min, and the gap between two adjacent second nitride structures along the preset direction is 0.3 μm.

[0102] Step S15: Use hydrofluoric acid to etch all mask patterns within the initial epitaxial wafer to form an air layer.

[0103] The concentration of hydrofluoric acid was 47%, the volume ratio of H2O to HF in the hydrofluoric acid was 9:1, the etching temperature was 20℃, the etching rate was 20nm / min, and the immersion time was 40min.

[0104] Step S16: Under the growth conditions of 1080℃, 100 torr, 800 rpm and V / III of 2000, gallium nitride is grown on both sides of each second nitride structure along the preset direction using an MOCVD device for 30 min to form a nitride layer on the air layer, thus obtaining a nitride epitaxial wafer.

[0105] Step S2: A light-emitting structure layer, a conductive layer, and a heat-dissipating bonding structure are sequentially formed on the nitride layer of the nitride epitaxial wafer to obtain the first LED epitaxial structure. The sequential formation of the light-emitting structure layer, conductive layer, and heat-dissipating bonding structure on the nitride layer of the nitride epitaxial wafer includes steps S21 and S23.

[0106] Step S21: A light-emitting structure layer is sequentially formed on the nitride layer of the nitride epitaxial wafer.

[0107] The light-emitting structure layer comprises an n-type gallium nitride layer, a multiple quantum well layer, an electron blocking layer, and a p-type gallium nitride layer, which are sequentially stacked. This step uses a commonly used existing process and will not be described in detail here.

[0108] Step S22: Under the conditions of working gas pressure of 0.3pa and RF power of 50W, a conductive layer with ITO material and a thickness of 100nm is sputtered on the light-emitting structure layer using magnetron sputtering process.

[0109] Step S23: A heat dissipation bonding structure is formed on the conductive layer using a metal vapor deposition process.

[0110] The heat dissipation bonding structure includes at least one metal layer stacked on the conductive layer. Forming the metal layer involves depositing a 50nm thick metal layer of Ti / Au material on the conductive layer to form the heat dissipation bonding structure. The metal evaporation process uses existing commonly used processes and will not be described in detail here.

[0111] Step S3: Remove the first nitride structure from the first LED epitaxial structure along the air layer to separate the substrate and the nitride layer, thereby obtaining the second LED epitaxial structure. Removing the first nitride structure from the first LED epitaxial structure along the air layer includes steps S31 and S32.

[0112] Step S31: At a deposition temperature of 200°C, a protective layer of SiO2 with a thickness of 150 nm is deposited on the side of the first LED epitaxial structure using the ALD process, exposing at least part of the air layer.

[0113] Step S32: Etch the first nitride structure along the exposed air layer at a temperature of 80°C. A 56% KOH solution is used as the etching solution.

[0114] Step S4: Form an N-type electrode on the nitride layer in the second LED epitaxial structure. Forming an N-type electrode on the nitride layer in the second LED epitaxial structure includes steps S41 and S45.

[0115] Step S41: The separation surface of the nitride layer in the second LED epitaxial structure is flattened to make the separation surface of the nitride layer a flat surface.

[0116] The leveling process includes repairing and cleaning the separation surfaces. The repair and cleaning of the separation surfaces utilizes existing common processes, which will not be elaborated upon here.

[0117] Step S42: Deposit an N-type electrode on the flat surface of the nitride layer in the second LED epitaxial structure. The deposition of the N-type electrode uses a commonly used existing process, which will not be described in detail here.

[0118] Step S5: An N-type ohmic contact layer of material Ti / Al / Ti / Au is formed on the side of the N-type electrode away from the nitride layer using a metal vapor deposition process.

[0119] The metal vapor deposition process uses existing and commonly used techniques, which will not be elaborated here.

[0120] Step S6: Bond the N-type contact layer to the target carrier using an electroplating process.

[0121] The target carrier is a substrate, and the electroplating process uses existing common processes, which will not be described in detail here. Step S7: Remove the temporary carrier, protective layer, and heat dissipation bonding structure. Removing the temporary carrier, protective layer, and heat dissipation bonding structure includes steps S71-S73.

[0122] Step S71: Dissociate the bonding layer to separate the temporary carrier from the heat dissipation bonding structure.

[0123] The bonding layer of PMMA material is dissociated by a pyrolysis process. The pyrolysis process adopts a commonly used existing process, which will not be described in detail here.

[0124] Step S72: Remove the heat dissipation bond structure.

[0125] The heat dissipation bonding structure is peeled off from the conductive layer by mechanical stripping. The mechanical stripping adopts existing common processes, which will not be described in detail here.

[0126] Step S73: Remove the protective layer using an HF solution. Example 2

[0127] This embodiment provides a method for fabricating an LED device, including the following steps S1-S7.

[0128] Step S1: An epitaxial structure is formed on a substrate to obtain a nitride epitaxial wafer. Forming an epitaxial structure on a substrate to obtain a nitride epitaxial wafer includes steps S11-S16.

[0129] Step S11: A mask layer with a thickness of 1 μm and made of silicon dioxide is deposited on the substrate (sapphire-based GaN template) by PECVD.

[0130] Step S12: Pattern the mask layer to obtain multiple mask patterns that are spaced apart along a preset direction.

[0131] The preset direction is the width direction of the sapphire-based GaN template. A growth window exposing the substrate is provided between two adjacent mask patterns. The width of the growth window 10 along the preset direction is 3μm, and the width of the mask pattern along the preset direction is 7μm.

[0132] Step S13: Under the growth conditions of 950℃, 600 torr, 650 rpm, and V / III ratio of 1250, a first nitride structure with gallium nitride and a thickness of 1 μm is grown in each growth window. The growth time is 60 min.

[0133] Step S14: Under the growth conditions of 1100℃, 150 torr, 900 rpm, and V / III of 2500, a second gallium nitride structure with a thickness of 2 μm is grown on each first nitride structure to obtain an initial epitaxial wafer. The growth time is 150 min, and the gap between two adjacent second nitride structures along the preset direction is 0.45 μm.

[0134] Step S15: Use hydrofluoric acid to etch all mask patterns within the initial epitaxial wafer to form an air layer.

[0135] The concentration of hydrofluoric acid was 49%, the volume ratio of H2O to HF in the hydrofluoric acid was 10:1, the etching temperature was 25℃, the etching rate was 35nm / min, and the immersion time was 40min.

[0136] Step S16: Under the growth conditions of 1100℃, 150 torr, 900rpm and V / III of 2500, gallium nitride is grown on both sides of each second nitride structure along the preset direction using an MOCVD device for 30min to form a nitride layer on the air layer, thus obtaining a nitride epitaxial wafer.

[0137] Step S2: A light-emitting structure layer, a conductive layer, and a heat-dissipating bonding structure are sequentially formed on the nitride layer of the nitride epitaxial wafer to obtain the first LED epitaxial structure. The sequential formation of the light-emitting structure layer, conductive layer, and heat-dissipating bonding structure on the nitride layer of the nitride epitaxial wafer includes steps S21 and S23.

[0138] Step S21: A light-emitting structure layer is sequentially formed on the nitride layer of the nitride epitaxial wafer. The light-emitting structure layer includes an n-type gallium nitride layer, a multiple quantum well layer, an electron blocking layer, and a p-type gallium nitride layer, which are sequentially stacked. This step uses a commonly used existing process and will not be described in detail here.

[0139] Step S22: Under the conditions of working gas pressure of 0.6pa and RF power of 125W, a conductive layer with ITO material and a thickness of 150nm is sputtered on the light-emitting structure layer using magnetron sputtering process.

[0140] Step S23: A heat dissipation bonding structure is formed on the conductive layer using a metal vapor deposition process.

[0141] The heat dissipation bonding structure includes at least one metal layer stacked on a conductive layer. Forming the metal layer involves depositing two metal layers of Ti / Au material with a thickness of 125 nm on the conductive layer to form the heat dissipation bonding structure. The metal evaporation process uses existing commonly used processes and will not be described in detail here.

[0142] Step S3: Remove the first nitride structure from the first LED epitaxial structure along the air layer to separate the substrate and the nitride layer, thereby obtaining the second LED epitaxial structure. Removing the first nitride structure from the first LED epitaxial structure along the air layer includes steps S31 and S32.

[0143] Step S31: At a deposition temperature of 275°C, a protective layer of SiO2 with a thickness of 175 nm is deposited on the side of the first LED epitaxial structure using the ALD process, exposing at least part of the air layer. Step S32: At a temperature of 100°C, the first nitride structure is etched along the exposed air layer. A 56% KOH solution is used as the etching solution.

[0144] Step S4: Form an N-type electrode on the nitride layer in the second LED epitaxial structure. Forming an N-type electrode on the nitride layer in the second LED epitaxial structure includes steps S41 and S45.

[0145] Step S41: The separation surface of the nitride layer in the second LED epitaxial structure is flattened to make the separation surface of the nitride layer a flat surface.

[0146] The leveling process includes repairing and cleaning the separation surfaces. The repair and cleaning of the separation surfaces utilizes existing common processes, which will not be elaborated upon here.

[0147] Step S42: Deposit an N-type electrode on the flat surface of the nitride layer in the second LED epitaxial structure. The deposition of the N-type electrode uses a commonly used existing process, which will not be described in detail here.

[0148] Step S5: An N-type ohmic contact layer of material Ti / Al / Ti / Au is formed on the side of the N-type electrode away from the nitride layer using a metal vapor deposition process.

[0149] The metal vapor deposition process uses existing and commonly used techniques, which will not be elaborated here.

[0150] Step S6: Bond the N-type contact layer to the target carrier using an electroplating process.

[0151] The target carrier is a substrate, and the electroplating process uses existing common processes, which will not be described in detail here.

[0152] Step S7: Remove the temporary carrier, protective layer, and heat dissipation bonding structure. Removing the temporary carrier, protective layer, and heat dissipation bonding structure includes steps S71-S73.

[0153] Step S71: Dissociate the bonding layer to separate the temporary carrier from the heat dissipation bonding structure.

[0154] The bonding layer of PMMA material is dissociated by a pyrolysis process. The pyrolysis process adopts a commonly used existing process, which will not be described in detail here.

[0155] Step S72: Remove the heat dissipation bond structure.

[0156] The heat dissipation bonding structure is peeled off from the conductive layer by mechanical stripping. The mechanical stripping adopts existing common processes, which will not be described in detail here.

[0157] Step S73: Remove the protective layer using an HF solution. Example 3

[0158] This embodiment provides a method for fabricating an LED device, including the following steps S1-S7. Step S1: Forming an epitaxial structure on a substrate to obtain a nitride epitaxial wafer. Forming an epitaxial structure on a substrate to obtain a nitride epitaxial wafer includes steps S11-S16.

[0159] Step S11: A mask layer with a thickness of 1.5 μm and made of silicon dioxide is deposited on the substrate (sapphire-based GaN template) by PECVD.

[0160] Step S12: Pattern the mask layer to obtain multiple mask patterns that are spaced apart along a preset direction.

[0161] The preset direction is the width direction of the sapphire-based GaN template. A growth window exposing the substrate is provided between two adjacent mask patterns. The width of the growth window 10 along the preset direction is 5μm, and the width of the mask pattern along the preset direction is 10μm.

[0162] Step S13: Under the growth conditions of 1000℃, 700 torr, 800 rpm, and V / III ratio of 1500, a first nitride structure with gallium nitride and a thickness of 1.5 μm is grown in each growth window. The growth time is 80 min.

[0163] Step S14: Under the growth conditions of 1120℃, 200 torr, 1000 rpm, and V / III of 3000, a second gallium nitride structure with a thickness of 4 μm is grown on each first nitride structure to obtain an initial epitaxial wafer. The growth time is 180 min, and the gap between two adjacent second nitride structures along the preset direction is 0.6 μm.

[0164] Step S15: Use hydrofluoric acid to etch all mask patterns within the initial epitaxial wafer to form an air layer.

[0165] The concentration of hydrofluoric acid was 51%, the volume ratio of H2O to HF in the hydrofluoric acid was 11:1, the etching temperature was 30℃, the etching rate was 50nm / min, and the immersion time was 40min.

[0166] Step S16: Under the growth conditions of 1120℃, 200 torr, 1000rpm and V / III of 3000, gallium nitride is grown on both sides of each second nitride structure along the preset direction using an MOCVD device for 30min to form a nitride layer on the air layer, thus obtaining a nitride epitaxial wafer.

[0167] Step S2: A light-emitting structure layer, a conductive layer, and a heat-dissipating bonding structure are sequentially formed on the nitride layer of the nitride epitaxial wafer to obtain the first LED epitaxial structure. The sequential formation of the light-emitting structure layer, conductive layer, and heat-dissipating bonding structure on the nitride layer of the nitride epitaxial wafer includes steps S21 and S23. Step S21: A light-emitting structure layer is sequentially formed on the nitride layer of the nitride epitaxial wafer. The light-emitting structure layer includes an n-type gallium nitride layer, a multiple quantum well layer, an electron blocking layer, and a p-type gallium nitride layer, which are sequentially stacked. This step uses a commonly used existing process and will not be described in detail here.

[0168] Step S22: Under the conditions of working gas pressure of 1pa and RF power of 200W, a conductive layer with ITO material and a thickness of 200nm is sputtered on the light-emitting structure layer using magnetron sputtering process.

[0169] Step S23: A heat dissipation bonding structure is formed on the conductive layer using a metal vapor deposition process.

[0170] The heat dissipation bonding structure includes at least one metal layer stacked on the conductive layer. Forming the metal layer involves depositing three metal layers of Ti / Au material with a thickness of 200 nm on the conductive layer to form the heat dissipation bonding structure. The metal evaporation process uses existing commonly used processes and will not be described in detail here.

[0171] Step S3: Remove the first nitride structure from the first LED epitaxial structure along the air layer to separate the substrate and the nitride layer, thereby obtaining the second LED epitaxial structure. Removing the first nitride structure from the first LED epitaxial structure along the air layer includes steps S31 and S32.

[0172] Step S31: At a deposition temperature of 350°C, a protective layer of SiO2 with a thickness of 200 nm is deposited on the side of the first LED epitaxial structure using the ALD process, exposing at least part of the air layer.

[0173] Step S32: Etch the first nitride structure along the exposed air layer at a temperature of 120°C.

[0174] The etching solution used is a 56% KOH solution.

[0175] Step S4: Form an N-type electrode on the nitride layer in the second LED epitaxial structure. Forming an N-type electrode on the nitride layer in the second LED epitaxial structure includes steps S41 and S45.

[0176] Step S41: The separation surface of the nitride layer in the second LED epitaxial structure is flattened to make the separation surface of the nitride layer a flat surface.

[0177] The leveling process includes repairing and cleaning the separation surfaces. The repair and cleaning of the separation surfaces utilizes existing common processes, which will not be elaborated upon here.

[0178] Step S42: Deposit an N-type electrode on the flat surface of the nitride layer in the second LED epitaxial structure. The deposition of the N-type electrode uses a commonly used existing process, which will not be described in detail here. Step S5: Form an N-type ohmic contact layer of material Ti / Al / Ti / Au on the side of the N-type electrode away from the nitride layer using a metal evaporation process.

[0179] The metal vapor deposition process uses existing and commonly used techniques, which will not be elaborated here.

[0180] Step S6: Bond the N-type contact layer to the target carrier using an electroplating process.

[0181] The target carrier is a substrate, and the electroplating process uses existing common processes, which will not be described in detail here.

[0182] Step S7: Remove the temporary carrier, protective layer, and heat dissipation bonding structure. Removing the temporary carrier, protective layer, and heat dissipation bonding structure includes steps S71-S73.

[0183] Step S71: Dissociate the bonding layer to separate the temporary carrier from the heat dissipation bonding structure.

[0184] The bonding layer of PMMA material is dissociated by a pyrolysis process. The pyrolysis process adopts a commonly used existing process, which will not be described in detail here.

[0185] Step S72: Remove the heat dissipation bond structure.

[0186] The heat dissipation bonding structure is peeled off from the conductive layer by mechanical stripping. The mechanical stripping adopts existing common processes, which will not be described in detail here.

[0187] Step S73: Remove the protective layer using an HF solution. Comparative Example 1

[0188] A method for fabricating an LED device is provided, comprising the following steps S1-S2.

[0189] Step S1: An epitaxial structure is formed on a substrate to obtain a nitride epitaxial wafer. Forming an epitaxial structure on a substrate to obtain a nitride epitaxial wafer includes steps S11-S16.

[0190] Step S11: A mask layer with a thickness of 1 μm and made of silicon dioxide is deposited on the substrate (sapphire-based GaN template) by PECVD.

[0191] Step S12: Pattern the mask layer to obtain multiple mask patterns that are spaced apart along a preset direction.

[0192] The preset direction is the width direction of the sapphire-based GaN template. A growth window exposing the substrate is provided between two adjacent mask patterns. The width of the growth window 10 along the preset direction is 3μm, and the width of the mask pattern along the preset direction is 7μm.

[0193] Step S13: Under the growth conditions of 950℃, 600 torr, 650 rpm, and V / III ratio of 1250, a first nitride structure with gallium nitride and a thickness of 1 μm is grown in each growth window. The growth time is 60 min.

[0194] Step S14: Under the growth conditions of 1100℃, 150 torr, 900 rpm, and V / III of 2500, a second gallium nitride structure with a thickness of 2 μm is grown on each first nitride structure to obtain an initial epitaxial wafer. The growth time is 150 min, and the gap between two adjacent second nitride structures along the preset direction is 0.45 μm.

[0195] Step S15: Under the growth conditions of 1100℃, 150 torr, 900rpm and V / III of 2500, gallium nitride is grown on both sides of each second nitride structure along the preset direction using an MOCVD device for 30min to form a nitride layer, thereby obtaining a nitride epitaxial wafer.

[0196] Step S2: An n-type gallium nitride layer, a multiple quantum well layer, an electron blocking layer, and a p-type gallium nitride layer are sequentially stacked on the nitride layer of the nitride epitaxial wafer to obtain an LED device.

[0197] This step uses existing and commonly used processes, which will not be elaborated on here. Comparative Example 2

[0198] A method for fabricating an LED device is provided, comprising: sequentially forming an n-type gallium nitride layer, a multiple quantum well layer, an electron blocking layer, and a p-type gallium nitride layer on a sapphire-based GaN template to obtain the LED device. The fabrication steps all employ existing commonly used processes and will not be described in detail here.

[0199] The LED devices prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to PL (Photoluminescence) and Raman spectroscopy tests. Table 1 shows the efficiency improvement ratio of In component incorporation in Examples 1-3 and Comparative Example 1 compared to Comparative Example 2, as well as the E2 (high) peak position.

[0200]

[0201] The In component incorporation efficiency of the LED devices in Examples 1-3 is significantly higher than that in Comparative Examples 1-2. This higher In component incorporation efficiency indicates that the LED devices prepared using the method of this invention generate less stress and have longer wavelengths, which is beneficial for the fabrication of long-wavelength LED devices. The E2 (high) peak position of the LED devices in Examples 1-3 is lower than that in Comparative Examples 1-2, indicating that the nitride epitaxial wafers prepared using the method of this invention generate less stress and produce higher quality LED devices.

[0202] 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 variations to the above embodiments within the scope of the invention without departing from the principles and spirit of the invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A method for fabricating an LED device, characterized in that, Includes the following steps: An epitaxial structure is formed on a substrate to obtain a nitride epitaxial wafer; wherein, the epitaxial structure includes a plurality of first nitride structures and a nitride layer covering all the first nitride structures, and a plurality of air layers are provided between the substrate and the nitride layer along a predetermined direction, and the air layers and the first nitride structures are alternately distributed on the substrate. A light-emitting structure layer is sequentially formed on the nitride layer of the nitride epitaxial wafer to obtain a first LED epitaxial structure; The first nitride structure in the first LED epitaxial structure is removed along the air layer to separate the substrate and the nitride layer, thereby obtaining a second LED epitaxial structure; wherein, the second LED epitaxial structure includes at least the nitride layer and the light-emitting structure layer stacked sequentially; An N-type electrode is formed on the nitride layer in the second LED epitaxial structure to obtain an LED device.

2. The preparation method according to claim 1, characterized in that, The thickness of the nitride layer is greater than the width of the first nitride structure; And / or, the material of the nitride layer is the same as the material of the first nitride structure.

3. The preparation method according to claim 1, characterized in that, The process of forming an epitaxial structure on a substrate to obtain a nitride epitaxial wafer includes: Multiple mask patterns are formed on the substrate at intervals along a predetermined direction; wherein, a growth window exposing the substrate is provided between two adjacent mask patterns; The first nitride structure comprising the target nitride is formed within each growth window; Under growth conditions of 1080–1120 °C, 100–200 torr, 800–1000 rpm, and V / III ratio of 2000–3000, a second nitride structure including the target nitride is formed on each of the first nitride structures to obtain an initial epitaxial wafer. Remove all the mask patterns within the initial epitaxial wafer to form an air layer on the substrate on at least one side of each second nitride structure; Under growth conditions of 1080–1120°C, 100–200 torr, 800–1000 rpm, and V / III of 2000–3000, the target nitride is grown on both sides of each second nitride structure along the preset direction, so that all the second nitride structures are merged to form a nitride layer on all the air layers, thus obtaining the nitride epitaxial wafer.

4. The preparation method according to any one of claims 1-3, characterized in that, The removal of the first nitride structure along the air layer includes: At a deposition temperature of 200–350°C, a protective layer of SiO2 material with a thickness of 150–200 nm is formed on the side of the first LED epitaxial structure, exposing at least part of the air layer. The first nitride structure is etched along the exposed air layer at a temperature of 80–120°C.

5. The preparation method according to claim 4, characterized in that, The first LED epitaxial structure further includes a conductive layer and a heat dissipation bonding structure sequentially stacked on the light-emitting structure layer. After the light-emitting structure layer is formed on the nitride layer of the nitride epitaxial wafer, the fabrication method further includes: Under the conditions of working gas pressure of 0.3 to 1 Pa and radio frequency power of 50 to 200 W, a conductive layer with ITO material and a thickness of 100 to 200 nm is sputtered on the light-emitting structure layer; A heat dissipation bonding structure is formed on the conductive layer, wherein the second LED epitaxial structure further includes the conductive layer and the heat dissipation bonding structure on the light-emitting structure layer stacked sequentially.

6. The preparation method according to claim 1, characterized in that, The formation of an N-type electrode on the nitride layer in the second LED epitaxial structure includes: The separation surface of the nitride layer in the second LED epitaxial structure is flattened to make the separation surface of the nitride layer a flat surface; The N-type electrode is deposited on the smooth surface of the nitride layer in the second LED epitaxial structure.

7. The preparation method according to claim 5, characterized in that, Before removing the first nitride structure from the first LED epitaxial structure along the air layer, the preparation method further includes: A bonding layer with a thickness of 3 to 5 μm is formed on the heat dissipation bonding structure to bond a temporary carrier to the heat dissipation bonding structure through the bonding layer.

8. The preparation method according to claim 5, characterized in that, The heat dissipation bonding structure includes at least one metal layer stacked on the conductive layer; forming the metal layer includes: A metal layer of Ti / Au material with a thickness of 50–200 nm is deposited on the conductive layer.

9. The preparation method according to claim 7, characterized in that, After forming an N-type electrode on the nitride layer in the second LED epitaxial structure, the fabrication method further includes: An N-type ohmic contact layer is formed on the side of the N-type electrode away from the nitride layer; The N-type contact layer is bonded to the target carrier; Remove the temporary carrier, the protective layer, and the heat dissipation bonding structure to obtain the LED device.

10. An LED device, characterized in that, It is prepared by any of the preparation methods in claims 1 to 9.

Images