Growth method of high-luminous-efficiency light-emitting diode epitaxial wafer

Abstract

The invention relates to the technical field of light-emitting diodes, in particular to a high-luminous-efficiency light-emitting diode epitaxial wafer growing method, which comprises the following steps: growing a substrate, growing a buffer layer on the substrate, growing a UGaN 1 layer on the substrate, growing a GR layer on the substrate, and growing an NGaN layer and an LED full-structure layer on the substrate; wherein the UGaN < 1 > layer comprises a 3D1 layer growing at a low temperature and a low growth speed, a recrystallization layer grows on the UGaN < 1 > layer, and a 3D2 layer grows on the UGaN < 1 > layer; wherein the temperature of the recrystallization layer is higher than that of the 3D1 layer, NH3 of the recrystallization layer is smaller than that of the 3D1 layer, and H2 is larger than that of the 3D1 According to the method, different atmospheres of a recrystallization layer are innovatively utilized to decompose GaN on a C surface / a non-C surface, so that the proportion of non-C-surface GaN crystals is eliminated, 3D2 high temperature and high growth speed are grown on the non-C-surface GaN crystals, mainly the C-surface GaN crystals, dislocation in contact with the non-C surface is eliminated, generation of holes is reduced by the GaN crystals grown at the top end of the patterned substrate, the lattice quality of an epitaxial material is improved, and the yield of the epitaxial material is improved. The luminous efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of light emitting diodes, and in particular relates to a method for growing a high-light-efficiency light emitting diode epitaxial wafer. Background Art

[0002] White light LEDs have replaced traditional lighting and become the preferred method for general indoor and outdoor lighting. How to improve the luminous efficiency of light-emitting diodes (LEDs) has become an important issue that needs to be addressed. Due to the properties of the material itself, mismatch stress in the epitaxial layer will introduce structural defects such as dislocations, stacking faults, and pores, which will deteriorate the crystal quality and reduce the luminous efficiency. How to improve the quality of epitaxial structure crystals has become an important issue in improving the luminous efficiency of LEDs.

[0003] At present, LED epitaxial wafers can reduce dislocation density and improve luminous efficiency through PSS patterned substrates. However, in the actual 3D growth process, a small amount of GaN crystals will also be generated on the non-polar surface of Al2O3, and will contact the GaN crystals grown on the C surface at the top and below of the substrate pattern, resulting in the following results: 1. Due to the different polarities of the two GaNs, it is difficult for atoms at the junction interface to form bonds, thus generating new dislocations or increasing the polarization effect at the junction interface due to the different polarities of GaN; 2. When the GaN crystal fills and covers the top of the substrate pattern, holes may be formed in the substrate pattern and its top area, thus affecting the luminous efficiency. Summary of the invention

[0004] In order to overcome the problems existing in the background technology, the present invention has developed a high-efficiency light-emitting diode epitaxial wafer growth method, the purpose of which is to: eliminate GaN crystals generated on non-C surfaces by inserting a recrystallization layer in the 3D layer, crack the GaN crystals generated on non-C surfaces on the patterned substrate through the recrystallization layer, avoid or reduce the generation of GaN crystals on non-C surfaces, and reduce the dislocation or polarization effect generated when GaN crystals of different polarities are bonded: to maximize the contact and bonding of GaN crystals generated on the C surface at the top of the substrate pattern, reduce the formation of voids in the substrate pattern and its top area, reduce the generation of dislocations and improve the lattice quality of the epitaxial layer, thereby improving the luminous efficiency.

[0005] To achieve the above object, the present invention adopts the following technical solution: A method for growing a high-efficiency light-emitting diode epitaxial wafer comprises: a substrate, a buffer layer grown on the substrate, a U_GaN1 layer grown thereon, a GR layer grown thereon, an NGaN layer and an LED full-structure layer grown thereon; wherein the U_GaN1 layer comprises a 3D1 layer grown at a low temperature and a low growth rate, a recrystallization layer grown thereon, and a 3D2 layer grown thereon; wherein the temperature of the recrystallization layer is greater than that of the 3D1 layer, the NH3 of the recrystallization layer is less than that of the 3D1 layer, and the H2 is greater than that of the 3D1 layer.

[0006] Preferably, a 3D2R1 recrystallization layer and a 3D2R2 recrystallization layer are sequentially grown on the 3D1 layer. The two recrystallization layers can quickly pull the temperature to a high level for better recrystallization.

[0007] Preferably, the growth conditions of the 3D1 layer are: temperature: 1030~1080 degrees, NH3: 15~80 SLM, N2: 25~100SLM, H2: 120~350 SLM, TMG flow: 160~500 Sccm, growth thickness is 0.03~0.09μm, pressure P=200 Torr; rotation speed: 700~900RPM.

[0008] Preferably, in the growth conditions of the 3D1 layer, NH3 accounts for 8% to 15%, N2 accounts for 15%~30%, H2 accounts for 50%~80%.

[0009] Preferably, the recrystallization layer growth conditions are: temperature: 1080~1100 degrees, NH3 flow rate is less than 3D1, H2 flow rate is greater than 3D1, growth time is 30s~3 min without Mo source introduction, pressure P=200 Torr; rotation speed: 700~900RPM, recrystallization time is 10~300s.

[0010] Preferably, the NH3 flow rate in the recrystallization layer growth condition includes NH3=0.

[0011] Preferably, the growth time of the 3D2R1 recrystallization layer is 10-60 seconds, and the growth time of the 3D2R2 recrystallization layer is 1-3 minutes.

[0012] Preferably, the 3D2R1-3D2R2 layers are cyclically grown for 5-loop times under the same conditions, and the non-C-plane GaN is repeatedly recrystallized to improve the lattice quality.

[0013] Preferably, the 3D2 layer growth conditions are: temperature: 1080~1100 degrees, NH3: 15~80 SLM, N2: 25~100SLM, H2: 120~350 SLM, TMG flow: 400~1600 Sccm, growth 5~12min, pressure P=200 Torr; rotation speed: 700~900RPM, 3D2 growth atmosphere conditions are the same as 3D1 (high temperature, fast growth rate).

[0014] Preferably, NH3 accounts for 8% to 15%, N2 accounts for 15% to 30%, and H2 accounts for 50% to 80% in the growth of the 3D2 layer.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention innovatively utilizes the different atmospheres of the recrystallization layer to decompose GaN on the C-face / non-C-face, thereby eliminating the proportion of non-C-face GaN crystals, and growing 3D2 at high temperature and high growth rate thereon, mainly GaN crystals on the C-face, which is beneficial to eliminate dislocations in contact with the non-C-face and reduce the generation of voids in the GaN crystals grown on the top of the patterned substrate, thereby improving the lattice quality of the epitaxial material and improving the luminescence efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 TEM image of the PSS pattern substrate and the actual grown U_GaN1 layer (3D layer) in the prior art.

[0017] Figure 2 This is a structural diagram of a high-light-efficiency light-emitting diode epitaxial wafer of the present invention.

[0018] Figure 3 This is a diagram of the epitaxial structure of the recrystallization layer of the present invention.

[0019] Figure 4 It is a process diagram for demonstrating the present invention.

[0020] Figure 5 It is a comparison diagram between the actual growth TEM image and the SEM image of the 3D layer of the present invention.

[0021] Figure 6 This is an example diagram of embodiment 2 of the present invention.

[0022] Figure 7 This is a comparison chart of epitaxial wafer data grown with the new and old epitaxial structures. DETAILED DESCRIPTION

[0023] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0024] like Figure 1 As shown, in the actual growth process of 3D by the existing growth method, a small amount of GaN crystals will also be generated on the non-polar surface of Al2O3, and will contact the GaN crystals grown on the C surface at the top and below of the substrate pattern, resulting in the following results: 1. Due to the different polarities of the two GaNs, it is difficult for the atoms at the junction interface to form bonds, thereby generating new dislocations or increasing the polarization effect at the junction interface due to the different polarities of GaN; 2. When the GaN crystal fills and covers the top of the substrate pattern, holes may be formed in the substrate pattern and its top area, thereby affecting the luminous efficiency (see Figure 1-1 ), Figure 1-2 This is the TEM image of the actual grown U_GaN1 layer (3D layer), which is basically consistent with the inferred growth.

[0025] like Figure 2As shown, the present invention provides a method for growing a high-efficiency light-emitting diode epitaxial wafer, comprising: a substrate, a buffer layer grown on the substrate, a U_GaN1 layer grown thereon, a GR layer grown thereon, an NGaN layer and an LED full-structure layer grown thereon; wherein the U_GaN1 layer includes a 3D1 layer grown at a low temperature and a low growth rate, a recrystallization layer grown thereon, and a 3D2 layer grown thereon; wherein the temperature of the recrystallization layer is greater than that of the 3D1 layer, the NH3 of the recrystallization layer is less than that of the 3D1 layer, and the H2 is greater than that of the 3D1 layer.

[0026] like Figure 3 As shown, in order to quickly pull the temperature to a high level and better recrystallize, the recrystallization layer includes a 3D2R1 recrystallization layer and a 3D2R2 recrystallization layer. The 3D2R1 recrystallization layer grows on the 3D1 layer, and the 3D2R2 recrystallization layer grows on the 3D2R1 recrystallization layer. Among them, the NH3 of the 3D2R1 / 2 pause layer is smaller than the 3D1 layer, the H2 of the 3D2R1 / 2 pause layer is larger than the 3D1 layer, the temperature of 3D2R1 / 2 is 30~50 degrees higher than the 3D1 layer, and the growth thickness of the 3D1 layer is 0.03~0.09μm. 3D1~3D2R2 grows cyclically, and the non-C-face grown GaN is repeatedly cracked and recrystallized to reduce the proportion of non-C-face GaN and improve the overall epitaxial layer lattice quality.

[0027] The generation and improvement process of dislocation / stress at the interface between GaN crystal on the non-C surface and GaN crystal grown on the C surface through the recrystallization layer epitaxial structure: Since the GaN grown on the buffer layer grows on the C-plane, the C-plane has strong polarity, and the presence of GaN nuclei is conducive to crystallization, the growth rate of GaN grown on the C-plane is fast and the proportion is high. The non-C-plane has weak polarity, so the generated GaN grows slowly and has a low proportion. In addition, the two epitaxial methods form GaN because of different polarities, which leads to difficulties in bonding and large polarization effects, thus affecting the lattice quality. The present invention utilizes different atmospheres in the recrystallization layer to decompose the GaN on the C-plane / non-C-plane, thereby eliminating the proportion of non-C-plane GaN crystals, and growing 3D2 high-temperature and high-growth-rate GaN crystals thereon, mainly on the C-plane, which is conducive to eliminating dislocations in contact with the non-C-plane and reducing the generation of voids in the GaN crystals grown on the top of the patterned substrate, thereby improving the lattice quality of the epitaxial material and improving the luminous efficiency. The demonstration process is shown in Figure 4 , the actual growth TEM image and 3D layer SEM image are compared under this condition. Figure 5 , which is basically consistent with the speculation.

[0028] The growth conditions of the U_GaN1 layer are: Embodiment 1: 3D1 layer growth conditions: Temp: 1030~1080 degrees, NH3: 15~80 SLM (NH3 accounts for 8%~15%), N2: 25~100SLM (N2 accounts for 15%~30%), H2: 120~350 SLM (H2 accounts for 50%~80%), TMG flow: 160~500 Sccm, growth thickness is 0.03~0.09μm, pressure P=200 Torr; rotation speed: 700~900RPM.

[0029] 3D2R1 / 2 recrystallization layer growth conditions: Temp: 1080~1100 degrees, NH3 flow rate is less than 3D1 (including NH3=0), H2 flow rate is greater than 3D1, growth time is 30s~3 min without Mo source, pressure P=200 Torr; rotation speed: 700~900RPM, recrystallization time is 10~300s.

[0030] 3D2 layer growth conditions: Temp: 1080~1100 degrees, NH3: 15~80 SLM (NH3 accounts for 8%~15%), N2: 25~100SLM (N2 accounts for 15%~30%), H2: 120~350 SLM (H2 accounts for 50%~80%), TMG flow: 400~1600 Sccm growth 5~12min pressure P=200 Torr; rotation speed: 700~900RPM, 3D2 growth atmosphere conditions are the same as 3D1 (high temperature, fast growth rate).

[0031] The 3D1~3D2R layers are grown cyclically for 5~loops under the same conditions, and the non-C-face GaN is repeatedly recrystallized to improve the lattice quality.

[0032] Embodiment 2: 3D1 layer growth conditions: Temp: 1030 degrees, NH3: 15~80 SLM (NH3 accounts for 8%~15%), N2: 25~100 SLM (N2 accounts for 15%~30%), H2: 120~350 SLM (H2 accounts for 50%~80%), TMG flow: 160~500 Sccm, growth thickness is 0.03~0.09μm, pressure P=200 Torr; rotation speed: 700~900RPM; the temperature of each cycle of the 3D1 layer is 5~10 higher than the previous cycle temperature (Temp: 1035~1070 degrees) until the last cycle temperature is 1080 degrees.

[0033] 3D2R1 / 2 recrystallization layer growth conditions: Temp: 1080~1100 degrees, NH3 flow rate is A (where A<3D1 NH3 flow rate), H2 flow rate is B (where B>3D1 H2 flow rate), growth for 30s~3 min without Mo source, pressure P=200Torr; rotation speed: 700~900RPM, recrystallization time 10~300s, where the growth temperature of each cycle is different from the previous cycle temperature (the recrystallization layer temperature is 30~50 degrees higher than the 3D1 layer temperature); each cycle growth gas volume is different from the previous cycle (the NH3 input amount of the recrystallization layer is less than 3D1, the H2 input amount is greater than 3D1, including one or more cycles NH3=0).

[0034] 3D2 layer growth conditions: Temp: 1080~1100 degrees, NH3:15~80 SLM (NH3 accounts for 8%~15%), N2: 25~100SLM (N2 accounts for 15%~30%), H2: 120~350 SLM (H2 accounts for 50%~80%), TMG flow: 400~1600 Sccm growth 5~12min pressure P=200 Torr; rotation speed: 700~900RPM, 3D2 growth atmosphere conditions are the same as 3D1 (high temperature, fast growth rate).

[0035] The 3D1~3D2R layers are grown 5~10 times in a cycle, where the temperature of the 3D1 layer is 5 degrees higher than the previous cycle in each cycle, and the temperature of the recrystallization layer is 20 degrees higher in each cycle. Figure 6 .

[0036] The present invention uses the same substrate, the same machine, and the old and new epitaxial structures to grow epitaxial wafers. The PL data test shows that the XRD data 002 / 102 of the new structure is significantly smaller, indicating that the lattice quality of the new structure is better, thereby achieving the ultimate purpose of improving the light efficiency. The specific data is shown in Figure 7 .

[0037] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for growing a high-efficiency light-emitting diode epitaxial wafer, characterized in that: The invention comprises: a substrate, a buffer layer grown on the substrate, a U_GaN1 layer grown thereon, a GR layer grown thereon, an NGaN layer and a full LED structure layer grown thereon; wherein the U_GaN1 layer comprises a 3D1 layer grown at a low temperature and a low growth rate, a recrystallization layer grown thereon, and a 3D2 layer grown thereon; wherein the temperature of the recrystallization layer is higher than that of the 3D1 layer, the NH3 of the recrystallization layer is lower than that of the 3D1 layer, and the H2 is higher than that of the 3D1 layer.

2. A method for growing a high-efficiency light-emitting diode epitaxial wafer as claimed in claim 1, wherein The characteristic is that The growth conditions of the 3D1 layer are: temperature: 1030~1080 degrees, NH3: 15~80 SLM, N2: 25~100SLM, H2: 120~350 SLM, TMG flow: 160~500 Sccm, growth thickness 0.03~0.09μm, pressure P=200 Torr; Speed: 700~900RPM.

3. A method for growing a high-efficiency light-emitting diode epitaxial wafer as claimed in claim 2, wherein The characteristic is that in the growth conditions of the 3D1 layer, NH3 accounts for 8%~15%, N2 accounts for 15%~30%, and H2 accounts for 50%~80%.

4. A method for growing a high-efficiency light-emitting diode epitaxial wafer as claimed in claim 3, characterized in that: The recrystallization layer growth conditions are as follows: temperature: 1080-1100 degrees, NH3 flow rate less than 3D1, H2 flow rate greater than 3D1, growth for 30s-3min without Mo source, pressure P=200 Torr; Rotation speed: 700~900RPM, recrystallization time 10~300s.

5. A method for growing a high-efficiency light-emitting diode epitaxial wafer as claimed in claim 4, characterized in that: The NH3 flow rate in the recrystallization layer growth condition includes NH3=0.

6. A method for growing a high-efficiency light-emitting diode epitaxial wafer as claimed in claim 5, characterized in that: A 3D2R1 recrystallized layer and a 3D2R2 recrystallized layer are sequentially grown on the 3D1 layer.

7. A method for growing a high-efficiency light-emitting diode epitaxial wafer as claimed in claim 6, characterized in that: The growth time of the 3D2R1 recrystallization layer is 10-60 seconds, and the growth time of the 3D2R2 recrystallization layer is 1-3 minutes.

8. A method for growing a high-efficiency light-emitting diode epitaxial wafer as claimed in claim 7, characterized in that: The 3D2R1-3D2R2 layers are cyclically grown for 5-loop times under the same conditions, and the non-C-face GaN is repeatedly recrystallized to improve the lattice quality.

9. A method for growing a high-efficiency light-emitting diode epitaxial wafer according to claim 5 or 8, characterized in that: The 3D2 layer growth conditions are as follows: temperature: 1080-1100 degrees, NH3: 15-80 SLM, N2: 25-100 SLM, H2: 120-350 SLM, TMG flow rate: 400-1600 Sccm, growth time 5-12 minutes, pressure P=200 Torr; Rotation speed: 700~900RPM. The growth atmosphere conditions of 3D2 are the same as those of 3D1 (high temperature and fast growth rate).

10. The method for growing a high-efficiency light-emitting diode epitaxial wafer according to claim 9, characterized in that: In the growth of 3D2 layer, NH3 accounts for 8%~15%, N2 accounts for 15%~30%, and H2 accounts for 50%~80%.

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