CN106409996A - Epitaxial growth method capable of improving LED chip property uniformity - Google Patents

Abstract

The invention discloses an epitaxial growth method capable of improving LED chip property uniformity. The method comprises the following steps in sequence: processing a patterned sapphire substrate, growing a stress releasing layer, growing a non-doped GaN layer, growing Si-doped N-type GaN layer, growing a multiple-quantum-well active layer, growing an electron blocking layer, growing a Mg-doped P-type GaN layer, and carrying out temperature reduction and cooling, wherein the step of growing the stress releasing layer is characterized by placing a sapphire substrate having an AlN film being sputtered thereon in an MOCVD reaction chamber; rising the temperature to 500-1000 DEG C; keeping the pressure in the reaction chamber to be 150-600 mbar; and growing the stress releasing layer, the thickness of which is 10-200 nm, the stress releasing layer being a GaN-based material, specifically, non-doped GaN, Si-doped GaN, or Mg-doped GaN, AlGaN, InGaN, AlInGaN.

Description

Epitaxial growth method for improving LED chip performance uniformity

technical field

The present application relates to the technical field of LED epitaxial design application, in particular, to an epitaxial growth method for improving the performance uniformity of LED chips.

Background technique

At present, LED (Light Emitting Diode, light-emitting diode) is a kind of solid-state lighting. Its advantages such as small size, low power consumption, long service life, high brightness, environmental protection, and durability are recognized by consumers, and the scale of domestic production of LEDs is gradually expanding. .

In recent years, the direct bandgap semiconductor material GaN has been widely used in light-emitting diode devices. Using DC magnetron reactive sputtering equipment to prepare AlN thin films on sapphire substrates, and then using metal-organic chemical vapor deposition (metal-organic chemical vapor deposition, MOCVD) can prepare GaN-based materials with higher crystal quality. This sputtering AlN growth GaN epitaxy technology is gradually replacing the traditional two-step growth method (first grow GaN, AlN, AlGaN and other buffer layers on heterogeneous substrates at low temperature, and then grow GaN, AlN, AlGaN and other materials after high-temperature annealing). However, due to the large lattice mismatch and thermal mismatch between sapphire and AlN materials, the epitaxial wafers grown by this technology have poor uniformity in performance, such as wavelength, thickness, brightness, etc., which seriously plagues the promotion of the technology.

Contents of the invention

In view of this, the technical problem to be solved in this application is to provide an epitaxial growth method to improve the performance uniformity of the LED chip. By introducing a stress release layer, the negative effects caused by lattice mismatch and thermal mismatch can be significantly weakened. The uniformity of wavelength, thickness and brightness in the epitaxial wafer is improved, which is conducive to the wide promotion of sputtering AlN growth GaN epitaxial technology.

In order to solve the above technical problems, the application has the following technical solutions:

An epitaxial growth method for improving the performance uniformity of an LED chip, characterized in that it sequentially includes: processing a patterned sapphire substrate, growing a stress release layer, growing a non-doped GaN layer, growing a Si-doped N-type GaN layer, growing Multi-quantum well active layer, growing electron blocking layer, growing Mg-doped P-type GaN layer, cooling down, wherein,

The process of processing the imaged sapphire substrate is as follows: using DC magnetron reactive sputtering equipment to heat the temperature of the sapphire substrate to 500°C-700°C, injecting Ar, N ₂ and O ₂ , using a 200V-300V bias Sputtering an AlN film with a thickness of 10nm to 200nm on the surface of the sapphire substrate by pressure impacting an aluminum target;

The growth of the stress release layer is as follows: put the sapphire substrate sputtered with the AlN thin film into the MOCVD reaction chamber, raise the temperature to 500°C-1000°C, keep the pressure of the reaction chamber at 150mbar-600mbar, and grow the thickness to 10nm - a 200nm stress release layer, the stress release layer is a GaN-based material, specifically: non-doped GaN, Si-doped GaN, or Mg-doped GaN, AlGaN, InGAN, AlInGaN.

Preferably, where:

In the Si-doped GaN, the Si doping concentration is 0 atoms/cm ³ -2E+19 atoms/cm ³ ;

In the Mg-doped GaN, AlGaN, InGAN, AlInGaN, the Mg doping concentration is 0 atoms/cm ³ −1+E21 atoms/cm ³ .

Preferably, where:

The growth of the non-doped GaN layer includes: increasing the temperature to 1000° C. to 1200° C., keeping the reaction chamber pressure at 150 mbar to 600 mbar, and growing the non-doped GaN layer with a thickness of 1 μm to 4 μm.

Preferably, where:

The growth of the Si-doped N-type GaN layer is: keep the temperature of the reaction chamber at 1000°C-1200°C, the pressure at 150mbar-600mbar, and grow the N-type GaN layer with a thickness of 1μm-4μm under a hydrogen atmosphere of 150mbar-300mbar , wherein the Si doping concentration is 5E+18 atoms/cm ³ -2E+19 atoms/cm ³ .

Preferably, where:

The growing multiple quantum well active layer is:

Lower the temperature to 700°C-750°C, keep the reaction chamber pressure at 300mbar-400mbar, and grow an In _x Ga ₍₁ -x)N potential well layer with a thickness of 2.5nm-3.5nm in a nitrogen atmosphere, where x=0.15 ～0.25, In doping concentration is 1E+20atoms/cm ³ ～5E+20atoms/cm ³ ;

Then raise the temperature to 800°C-850°C, keep the pressure of the reaction chamber constant, and grow a GaN barrier layer with a thickness of 8nm-12nm;

The potential well layer and the potential barrier layer are alternately grown with a growth period of 6-15 to prepare an InxGa ₍₁ - _x )N/GaN multi-quantum well active layer.

Preferably, where:

The growth of the electron blocking layer is: increasing the temperature to 800°C-900°C, and growing a P-type Al _y Ga _(1-y) N electron blocking layer with a thickness of 10nm-200nm under the reaction chamber pressure of 200mbar-400mbar , wherein, y=0.1˜0.3, Al doping concentration is 1E+20atoms/cm ³ ˜3E+20atoms/cm ³ , Mg doping concentration is 5E+18atoms/cm ³ ˜1E+19atoms/cm ³ .

Preferably, where:

The growth of the P-type GaN layer doped with Mg is as follows: increasing the temperature to 930°C-950°C, and growing a P-type GaN layer of 30nm-300nm under the reaction chamber pressure of 200mbar-600mbar, wherein the Mg doping concentration is It is 1E+19 atoms/cm ³ to 1E+20 atoms/cm ³ .

Preferably, where:

The temperature-lowering cooling includes: lowering the temperature to 700° C. to 800° C., annealing in a furnace for 20 minutes to 30 minutes, and then cooling to room temperature.

Compared with the prior art, the method described in this application has achieved the following effects:

(1) The epitaxial growth method of the present invention to improve the performance uniformity of the LED chip, compared with the traditional method, adds a stress release layer, the stress release layer has better relaxation than high-temperature GaN, and can release GaN and AlN templates well The direct lattice stress improves the warpage of the wafer during epitaxial growth and makes the temperature inside the chip more uniform, that is, improves the consistency of the growth rate in the chip during epitaxial growth, thus improving the thickness uniformity of GaN materials.

(2) The epitaxial growth method of the present invention improves the performance uniformity of the LED chip, and the added stress release layer well releases the stress caused by the lattice mismatch of the GaN material, so that the internal temperature of the wafer when growing the quantum well changes. Uniform, thus obtaining higher wavelength consistency.

(3) The epitaxial growth method of the present invention improves the performance uniformity of the LED chip. After adding the stress release layer, the surface temperature of the wafer becomes uniform, so that the consistency of the epitaxial growth of each structure is improved, and the luminous intensity is naturally higher. Good uniformity; in addition, the increase in the uniformity of the wavelength indicates that the distribution of InGaN in the quantum well region of sample A is more uniform, which is conducive to improving the brightness and uniformity of the epitaxial wafer.

Description of drawings

The drawings described here are used to provide a further understanding of the application and constitute a part of the application. The schematic embodiments and descriptions of the application are used to explain the application and do not constitute an improper limitation to the application. In the attached picture:

Fig. 1 is the flow chart of the epitaxial growth method of improving LED chip performance uniformity of the present invention;

Fig. 2 is the structural representation of LED epitaxial layer in the present invention;

Fig. 3 is the structural representation of LED epitaxial layer in comparative example;

Fig. 4 is a comparison diagram of the distribution of GaN-based material thickness of sample A and sample B using PL;

Figure 5 is a comparison chart of the wavelength distribution of sample A and sample B using PL;

Figure 6 is a comparison diagram of the distribution of luminous intensities of sample A and sample B using PL;

Among them, 1. patterned sapphire substrate, 2. sputtered AlN buffer layer, 3. u-type GaN layer, 4. n-type GaN layer, 5. multi-quantum well active layer, 6. p-type AlGaN layer, 7. P-type GaN layer, 8. Stress release layer.

detailed description

Certain terms are used, for example, in the description and claims to refer to particular components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in name as a way to distinguish components, but use the difference in function of components as a criterion for distinguishing. As mentioned throughout the specification and claims, "comprising" is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. In addition, the term "coupled" herein includes any direct and indirect electrical coupling means. Therefore, if it is described that a first device is coupled to a second device, it means that the first device may be directly electrically coupled to the second device, or indirectly electrically coupled through other devices or coupling means. connected to the second device. The subsequent description of the specification is a preferred implementation mode for implementing the application, but the description is for the purpose of illustrating the general principles of the application, and is not intended to limit the scope of the application. The scope of protection of the present application should be defined by the appended claims.

Example 1

The present invention uses the RMS equipment model iTop A230 to sputter AlN film on PSS as the buffer layer of GaN epitaxial growth, and its carrier gas is high-purity nitrogen (N ₂ ), high-purity helium (Ar) and a small amount of high-purity oxygen ( O ₂ ), the target material is high-purity metal aluminum (Al), and the DC sputtering voltage is 200-300V. Use veeco company model K465i MOCVD equipment to grow high-brightness GaN-based LED epitaxial wafers, use high-purity hydrogen (H ₂ ), high-purity nitrogen (N ₂ ) as carrier gas, and high-purity ammonia (NH ₃ ) as N source , metal-organic sources trimethylgallium (TMGa) and triethylgallium (TEGa) as gallium source, trimethylindium (TMIn) as indium source, trimethylaluminum (TMAl) as aluminum source, silane (SiH4) as The N-type dopant, magnesium dicene (CP2Mg) is used as the P-type dopant.

The epitaxial growth method for improving the performance uniformity of the LED chip provided by the present invention sequentially includes: processing a patterned sapphire substrate, growing a stress release layer, growing a non-doped GaN layer, growing an N-type GaN layer doped with Si, growing a poly Quantum well active layer, growing electron blocking layer, growing Mg-doped P-type GaN layer, cooling down, wherein,

The process of processing the imaged sapphire substrate is as follows: using DC magnetron reactive sputtering equipment to heat the temperature of the sapphire substrate to 500°C-700°C, injecting Ar, N ₂ and O ₂ , using a 200V-300V bias Sputtering an AlN film with a thickness of 10nm to 200nm on the surface of the sapphire substrate by pressure impacting an aluminum target;

The growth of the stress release layer is as follows: put the sapphire substrate sputtered with the AlN thin film into the MOCVD reaction chamber, raise the temperature to 500°C-1000°C, keep the pressure of the reaction chamber at 150mbar-600mbar, and grow the thickness to 10nm - a 200nm stress release layer, the stress release layer is a GaN-based material, specifically: non-doped GaN, Si-doped GaN, or Mg-doped GaN, AlGaN, InGAN, AlInGaN.

In the aforementioned Si-doped GaN, the Si doping concentration is 0-2E+19 atoms/cm ³ ; in the Mg-doped GaN, AlGaN, InGAN, AlInGaN, the Mg doping concentration is 0-1+E21 atoms/cm ³ .

The stress release layer adopted by the present invention can significantly weaken the negative effects caused by lattice mismatch and thermal mismatch, improve the uniformity of wavelength, thickness, and brightness in the epitaxial wafer, and is conducive to the development of sputtering AlN growth GaN epitaxy technology Promote widely.

Example 2

The application examples of the epitaxial growth method for improving LED chip performance uniformity of the present invention are provided below, the epitaxial structure is shown in FIG. 2 , and the growth method is shown in FIG. 1 . The AlN thin film was sputtered on the PSS by RMS equipment model iTop A230 as a buffer layer for GaN epitaxial growth, and the carrier gas was high-purity nitrogen (N ₂ ), high-purity helium (Ar) and a small amount of high-purity oxygen (O ₂ ), the target material is high-purity metal aluminum (Al), and the DC sputtering voltage is 200-300V. Use veeco company model K465i MOCVD equipment to grow high-brightness GaN-based LED epitaxial wafers, use high-purity hydrogen (H ₂ ), high-purity nitrogen (N ₂ ) as carrier gas, and high-purity ammonia (NH ₃ ) as N source , metal-organic sources trimethylgallium (TMGa) and triethylgallium (TEGa) as gallium source, trimethylindium (TMIn) as indium source, trimethylaluminum (TMAl) as aluminum source, silane (SiH4) as The N-type dopant, magnesium dicene (CP2Mg) is used as the P-type dopant. The specific growth method is as follows:

Step 101, processing the patterned sapphire substrate:

Use DC magnetron reactive sputtering equipment to heat the temperature of the sapphire substrate to 500°C-700°C, pass through Ar, N ₂ and O ₂ , and impact the aluminum target on the surface of the sapphire substrate with a bias voltage of 200V-300V AlN film with a thickness of 10nm-200nm is sputtered on top.

Step 102, growing a stress release layer:

Put the sapphire substrate sputtered with the AlN thin film into the MOCVD reaction chamber, raise the temperature to 500°C-1000°C, keep the reaction chamber pressure at 150mbar-600mbar, and grow a stress release layer with a thickness of 10nm-200nm, the The stress release layer is a GaN-based material, specifically: non-doped GaN, Si-doped GaN, or Mg-doped GaN, AlGaN, InGAN, AlInGaN. In the aforementioned Si-doped GaN, the Si doping concentration is 0-2E+19 atoms/cm ³ ; in the Mg-doped GaN, AlGaN, InGAN, AlInGaN, the Mg doping concentration is 0-1+E21 atoms/cm ³ .

Step 103, growing a non-doped GaN layer:

The temperature is raised to 1000° C. to 1200° C., the pressure of the reaction chamber is maintained at 150 mbar to 600 mbar, and a non-doped GaN layer with a thickness of 1 μm to 4 μm is grown.

Step 104, growing an N-type GaN layer doped with Si:

Keep the temperature of the reaction chamber at 1000°C-1200°C, the pressure at 150mbar-600mbar, and grow an N-type GaN layer with a thickness of 1μm-4μm in a hydrogen atmosphere of 150mbar-300mbar, wherein the Si doping concentration is 5E+18atoms/cm ³ ~2E+19 atoms/cm ³ .

In this application, 5E18 represents 5 times 10 to the 18th power, that is, 5*10 ¹⁸ , and so on, atoms/cm ³ is the unit of doping concentration, the same below.

Step 105, growing the multi-quantum well active layer:

Lower the temperature to 700°C-750°C, keep the reaction chamber pressure at 300mbar-400mbar, and grow an In _x Ga ₍₁ -x)N potential well layer with a thickness of 2.5nm-3.5nm in a nitrogen atmosphere, where x=0.15 ～0.25, In doping concentration is 1E+20atoms/cm ³ ～5E+20atoms/cm ³ ;

Then raise the temperature to 800°C-850°C, keep the pressure of the reaction chamber constant, and grow a GaN barrier layer with a thickness of 8nm-12nm;

The potential well layer and the potential barrier layer are alternately grown with a growth period of 6-15 to prepare an In _x Ga _(1-x) N/GaN multi-quantum well active layer.

Step 106, growing an electron blocking layer:

raising the temperature to 800°C to 900°C, and growing a P-type Al _y Ga _(1-y) N electron blocking layer with a thickness of 10nm to 200nm under a reaction chamber pressure of 200mbar to 400mbar, where y=0.1 to 0.3, Al doping concentration is 1E+20atoms/cm ³ -3E+20atoms/cm ³ , and Mg doping concentration is 5E+18atoms/cm ³ -1E+19atoms/cm ³ .

Step 107, growing a P-type GaN layer doped with Mg:

Raise the temperature to 930°C-950°C, and grow a P-type GaN layer of 30nm-300nm under the reaction chamber pressure of 200mbar-600mbar, wherein the Mg doping concentration is 1E+19atoms/cm ³ ～1E+20atoms/cm ³ .

Step 108, cooling down:

Lower the temperature to 700°C to 800°C, anneal in the furnace for 20min to 30min, and then cool to room temperature.

Example 3

A conventional GaN-based LED device epitaxial growth method is provided below as a comparative example of the present invention.

The growth method of conventional LED epitaxy is (refer to Figure 3 for the epitaxial layer structure):

1. Use DC magnetron reactive sputtering equipment to heat the PSS temperature to about 500°C-700°C, feed helium (Ar), nitrogen (N ₂ ) and oxygen (O ₂ ), and impact with a bias voltage of 200V-300V The aluminum target sputters a 10nm-200nm thick AlN film on the surface of the PSS.

2. Put the PSS substrate sputtered with AlN film into the MOCVD reaction chamber, raise the temperature to 1000°C-1200°C, reduce the pressure to 150mbar-600mbar, and feed NH ₃ to prevent the AlN film from decomposing.

3. Maintaining the temperature at 1000° C. to 1200° C. and growing a non-doped GaN layer with a thickness of 1 μm to 4 μm under a pressure of 150 mbar to 600 mbar.

4. Maintain the temperature and pressure of the reaction chamber, grow an N-type GaN layer with a thickness of 1 μm to 4 μm in a hydrogen atmosphere of 150 mbar to 300 mbar, and a Si doping concentration of 5E+18atoms/cm ³ to 2E+19atoms/cm ³ .

5. Lower the temperature to 700°C-750°C, and grow In _x Ga _(1-x) N (x=0.15-0.25) potential well layer with a thickness of 2.5nm-3.5nm under a nitrogen atmosphere of 300mbar-400mbar, and In doping The concentration is 1E+20atoms/cm ³ ~5E+20atoms/cm ³ ; then raise the temperature to 800°C~850°C, keep the pressure constant, and grow a GaN barrier layer with a thickness of 8nm~12nm; alternately grow potential well layers and potential The barrier layer has 6-15 periods, and the In _x Ga _(1-x) N/GaN multi-quantum well active layer is prepared.

6. Raise the temperature to 800°C~900°C, and grow a P-type Al _y Ga _(1-y) N (y=0.1~0.3) electron blocking layer of 10nm~200nm under the pressure of 200mbar~400mbar, and the Al doping concentration is 1E +20 atoms/cm 3 -3E+20 atoms/cm ³ , Mg doping concentration is 5E+ ¹⁸ atoms/cm ³ -1E+19 atoms/cm ³ .

7. Raise the temperature to 930°C-950°C, grow a P-type GaN layer of 30nm-300nm under the pressure of 200mbar-600mbar, and the Mg doping concentration is 1E+19atoms/cm ³ -1E+20atoms/cm ³ .

8. Finally, lower the temperature to 700°C to 800°C, anneal in the furnace for 20 to 30 minutes, and then cool to room temperature.

On the same machine, epitaxial wafer sample A was prepared according to the method described in this patent, its epitaxial structure is shown in Figure 2, and sample B was prepared according to the conventional LED growth method (the method of the comparative example), and its epitaxial structure was shown in Figure 3.

Fig. 2 and Fig. 3 are LED epitaxial structure diagrams in the present application and comparative examples respectively, and the difference between sample A and sample B epitaxial growth method parameters lies in the stress release layer in Fig. 2, namely the present invention sputters AlN buffer layer and A stress release layer with a thickness of 10nm-200nm is inserted between the doped GaN.

Table 1 is a comparison table of thickness, wavelength, luminous intensity and standard deviation (Std Dev, Standard Deviation) of GaN material after sample A and sample B are tested by PL (photoluminescence tester). Obviously, after adding the stress release layer in the present application, compared with sample B, the standard deviation of the thickness of the epitaxial wafer of sample A, the standard deviation of the wavelength and the standard deviation of the light intensity are all significantly reduced, that is to say, the thickness of the epitaxial wafer , wavelength, and luminous intensity have better uniformity, and it is of great help to improve the yield rate of the product after the epitaxial wafer is made into a chip.

Table 1 Comparison table of thickness, wavelength and brightness of epitaxial wafer samples A and B

sample Thickness/μm Thickness STD wavelength/nm Wavelength STD light intensity light intensity STD Cases of the invention 6.89 0.02 456.24 0.82 20.96 1.17 traditional case 6.99 0.07 456.69 6.98 14.52 3.23

Fig. 4 is a distribution diagram of the thickness of epitaxial wafer sample A prepared by the method of the present application and tested using PL (photoluminescence tester) and the thickness of the GaN-based material of the sample and the process of using the comparative example to prepare epitaxial wafer sample B using PL (photoluminescence tester) Instrument) The distribution diagram of the thickness of the test sample GaN-based material. It can be clearly seen from Fig. 4 that the thickness of the GaN-based material of sample A prepared by the method of the present application is distributed between 6.85 μm and 6.93 μm, and the thickness difference within the chip is 0.08 μm, which has good uniformity. However, the thickness of the GaN material of the sample B prepared by the process of the comparative example is distributed between 6.88 μm and 7.07 μm, and the thickness difference within the chip is 0.19 μm, and the uniformity is poor.

The reason why the thickness uniformity of the above-mentioned sample A has been significantly improved is that the stress release layer added in the method of this application has better relaxation than high-temperature GaN, which can well release the direct lattice stress between GaN and AlN templates, and improves the epitaxy. The warping of the wafer during growth makes the temperature in the chip more uniform, which improves the consistency of the growth rate in the chip during epitaxial growth, thus improving the thickness uniformity of the GaN material.

Fig. 5 is the distribution diagram of the wavelength of sample A prepared by the method of the present application and tested by PL (photoluminescence tester) and the sample B of epitaxial wafer prepared by the process of comparative example by using PL (photoluminescence tester) Distribution plot of test sample B wavelength. It can be seen from Figure 5 that the wavelength distribution of sample A is 455.87nm-457.33nm, with a difference of 1.46nm, which has good intra-chip uniformity, while the wavelength distribution of sample B is 440.6-467.42nm, with a difference of 26.86nm nm, the uniformity is very poor, causing a lot of trouble for the handsome selection work after the epitaxial wafer is made into a chip.

The reason why the wavelength uniformity of the above-mentioned sample A has been significantly improved is that the stress release layer added can well release the stress caused by the lattice mismatch of the GaN material, which is why the temperature inside the wafer becomes uniform when growing quantum wells. Thus a higher wavelength uniformity is obtained.

Fig. 6 is a distribution diagram of the luminous intensity of the sample A prepared by the method of the present application and tested using the PL (photoluminescence tester) sample A and the process of the comparative example to prepare the epitaxial wafer sample B using the PL (photoluminescence tester) ) The distribution diagram of the luminous intensity of test sample B. It can be seen from Figure 6 that the luminous intensity distribution of sample A is 19.9-21.76, the difference is 1.86, and the uniformity is very good, while the luminous intensity of sample B is distributed between 8.87-20.34, the difference is 11.47, and the uniformity is very poor.

The reason why the above-mentioned sample A has higher uniformity of luminous intensity is that after adding the stress release layer, the surface temperature of the wafer becomes uniform, which improves the consistency of the epitaxial growth of each structure, and the luminous intensity naturally has better Uniformity; In addition, the increase in the uniformity of the wavelength indicates that the distribution of InGaN in the quantum well region of sample A is more uniform, which is beneficial to improving the brightness and uniformity of the epitaxial wafer.

In summary, the epitaxial growth method for improving the performance uniformity of LED chips provided by this application can significantly weaken the negative effects caused by lattice mismatch and thermal mismatch by introducing a stress release layer, and improve the wavelength, The uniformity of thickness and brightness is conducive to the widespread promotion of sputtering AlN growth GaN epitaxial technology.

Can know by above each embodiment, the beneficial effect that the present application exists is:

(1) The epitaxial growth method of the present invention to improve the performance uniformity of the LED chip, compared with the traditional method, adds a stress release layer, the stress release layer has better relaxation than high-temperature GaN, and can release GaN and AlN templates well The direct lattice stress improves the warpage of the wafer during epitaxial growth and makes the temperature inside the chip more uniform, that is, improves the consistency of the growth rate in the chip during epitaxial growth, thus improving the thickness uniformity of GaN materials.

(2) The epitaxial growth method of the present invention improves the performance uniformity of the LED chip, and the added stress release layer well releases the stress caused by the lattice mismatch of the GaN material, so that the internal temperature of the wafer when growing the quantum well changes. Uniform, thus obtaining higher wavelength consistency.

(3) The epitaxial growth method of the present invention improves the performance uniformity of the LED chip. After adding the stress release layer, the surface temperature of the wafer becomes uniform, so that the consistency of the epitaxial growth of each structure is improved, and the luminous intensity is naturally higher. Good uniformity; in addition, the increase in the uniformity of the wavelength indicates that the distribution of InGaN in the quantum well region of sample A is more uniform, which is conducive to improving the brightness and uniformity of the epitaxial wafer.

Those skilled in the art should understand that the embodiments of the present application may be provided as methods, apparatuses, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various Various other combinations, modifications, and environments can be made within the scope of the inventive concept described herein, by the above teachings or by skill or knowledge in the relevant field. However, modifications and changes made by those skilled in the art do not depart from the spirit and scope of the present application, and should all be within the protection scope of the appended claims of the present application.

Claims (8)

1. An epitaxial growth method for improving the uniformity of LED chip performance, characterized in that it comprises in turn: processing a patterned sapphire substrate, growing a stress release layer, growing a non-doped GaN layer, and growing an N-type GaN layer doped with Si , growing a multi-quantum well active layer, growing an electron blocking layer, growing a Mg-doped P-type GaN layer, and cooling, wherein, The process of processing the imaged sapphire substrate is as follows: using DC magnetron reactive sputtering equipment to heat the temperature of the sapphire substrate to 500°C-700°C, injecting Ar, N ₂ and O ₂ , using a 200V-300V bias Sputtering an AlN film with a thickness of 10nm to 200nm on the surface of the sapphire substrate by pressure impacting an aluminum target; The growth of the stress release layer is as follows: put the sapphire substrate sputtered with the AlN thin film into the MOCVD reaction chamber, raise the temperature to 500°C-1000°C, keep the pressure of the reaction chamber at 150mbar-600mbar, and grow the thickness to 10nm - a 200nm stress release layer, the stress release layer is a GaN-based material, specifically: non-doped GaN, Si-doped GaN, or Mg-doped GaN, AlGaN, InGAN, AlInGaN. 2. The epitaxial growth method for improving LED chip performance uniformity according to claim 1, characterized in that, In the Si-doped GaN, the Si doping concentration is 0 atoms/cm ³ -2E+19 atoms/cm ³ ; In the Mg-doped GaN, AlGaN, InGAN, AlInGaN, the Mg doping concentration is 0 atoms/cm ³ −1+E21 atoms/cm ³ . 3. The epitaxial growth method for improving the uniformity of LED chip performance according to claim 1, characterized in that, The growth of the non-doped GaN layer includes: increasing the temperature to 1000° C. to 1200° C., keeping the reaction chamber pressure at 150 mbar to 600 mbar, and growing the non-doped GaN layer with a thickness of 1 μm to 4 μm. 4. The epitaxial growth method for improving LED chip performance uniformity according to claim 1, characterized in that, The growth of the Si-doped N-type GaN layer is: keep the temperature of the reaction chamber at 1000°C-1200°C, the pressure at 150mbar-600mbar, and grow the N-type GaN layer with a thickness of 1μm-4μm under a hydrogen atmosphere of 150mbar-300mbar , wherein the Si doping concentration is 5E+18 atoms/cm ³ -2E+19 atoms/cm ³ . 5. The epitaxial growth method for improving LED chip performance uniformity according to claim 1, characterized in that, The growing multiple quantum well active layer is: Lower the temperature to 700°C-750°C, keep the reaction chamber pressure at 300mbar-400mbar, and grow an In _x Ga _(1-x) N potential well layer with a thickness of 2.5nm-3.5nm in a nitrogen atmosphere, where x=0.15 ～0.25, In doping concentration is 1E+20atoms/cm ³ ～5E+20atoms/cm ³ ; Then raise the temperature to 800°C-850°C, keep the pressure of the reaction chamber constant, and grow a GaN barrier layer with a thickness of 8nm-12nm; The potential well layer and the potential barrier layer are alternately grown with a growth period of 6-15 to prepare an In _x Ga _(1-x) N/GaN multi-quantum well active layer. 6. The epitaxial growth method for improving LED chip performance uniformity according to claim 1, characterized in that, The growth of the electron blocking layer is: increasing the temperature to 800°C-900°C, and growing a P-type Al _y Ga _(1-y) N electron blocking layer with a thickness of 10nm-200nm under the reaction chamber pressure of 200mbar-400mbar , wherein, y=0.1˜0.3, Al doping concentration is 1E+20atoms/cm ³ ˜3E+20atoms/cm ³ , Mg doping concentration is 5E+18atoms/cm ³ ˜1E+19atoms/cm ³ . 7. The epitaxial growth method for improving LED chip performance uniformity according to claim 1, characterized in that, The growth of the P-type GaN layer doped with Mg is as follows: increasing the temperature to 930°C-950°C, and growing a P-type GaN layer of 30nm-300nm under the reaction chamber pressure of 200mbar-600mbar, wherein the Mg doping concentration is It is 1E+19 atoms/cm ³ to 1E+20 atoms/cm ³ . 8. The epitaxial growth method for improving LED chip performance uniformity according to claim 1, characterized in that, The temperature-lowering cooling includes: lowering the temperature to 700° C. to 800° C., annealing in a furnace for 20 minutes to 30 minutes, and then cooling to room temperature.