Method for fabricating ultraviolet light emitting diode

Abstract

The application discloses a method for manufacturing a UV light emitting diode, which comprises the following steps in sequence: performing a desorption treatment on a substrate, growing an AlN buffer layer on the substrate, manufacturing an AlN buffer layer pattern, performing an annealing treatment, performing an ammoniation treatment, growing an AlN template layer, growing a BN layer, growing a BGaN layer, growing an AlGaN transition layer, growing an AlGaN multi-quantum well layer, and growing an AlGaN protective layer, so as to form a light emitting diode epitaxial wafer with a complete structure. The application forms a metal polarity and nitrogen polarity alternating growth structure in the LED to improve the light emitting intensity of the light emitting diode, and the ammoniation treatment and the introduction of the BN layer and the BGaN layer improve the material crystal quality, so that the light emitting efficiency of the LED is further improved, and the anti-static capability is enhanced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of semiconductor, and particularly relates to a method for manufacturing an ultraviolet light emitting diode. BACKGROUND

[0002] A light emitting diode (LED) is a kind of semiconductor electronic device which converts electrical energy into light energy. As a new type of solid-state lighting source with high efficiency, environmental protection and green, LED has been widely used in traffic signal lights, car lights, indoor and outdoor lighting, display screens.

[0003] In recent years, the ultraviolet LED technology has developed rapidly, and is more and more widely used in people's life and production, and has also attracted more attention and become the object of competition. The ultraviolet light spectrum ranges from about 100 nm to 400 nm, and different wavelength ranges of ultraviolet light have different application fields. In addition to lighting, ultraviolet LED has also been involved in other fields. Including sterilization (390-410 nm), medical treatment (300-320 nm), biological medicine (270-300 nm), polymer printing (300-365 nm), barcode verification (230-280 nm), body fluid detection identification and analysis (250-405 nm), water sterilization (230-400 nm), and optical sensor instruments (230-400 nm).

[0004] Due to the advantages of small size, long life, safety and reliability, and no pollution, ultraviolet LED is an ideal candidate to replace traditional fragile and toxic ultraviolet mercury lamps. Compared with blue and white light LED, the photoelectric conversion efficiency of ultraviolet LED is still relatively low, and more efforts need to be made for related research. At present, ultraviolet LED still has problems such as high working voltage, low quantum efficiency, and serious heating, which hinders its widespread application in daily life. The most important factor affecting the development of ultraviolet LED is its luminous efficiency. Compared with blue light LED, the luminous efficiency of ultraviolet LED is very low. If the luminous efficiency of ultraviolet LED can be improved, ultraviolet LED will have greater development space.

[0005] Therefore, it is a technical problem to be solved in the technical field to provide a method for manufacturing an ultraviolet light emitting diode to solve the problem of low luminous efficiency of the existing ultraviolet LED, so as to meet the application needs of ultraviolet LED. SUMMARY

[0006] The present application improves the luminous intensity of the light emitting diode by forming a metal polarity and nitrogen polarity alternating growth structure inside the LED, and improves the material crystal quality by ammonia treatment and introduction of BN layer and BGaN layer, thereby further improving the luminous efficiency of the LED and enhancing the anti-static ability.

[0007] The application discloses a method for manufacturing ultraviolet light emitting diode, which is characterized by comprising the following steps.

[0008] Step one, put the substrate into the MOCVD reaction chamber for desorption treatment;

[0009] Step two, grow AlN buffer layer on the substrate;

[0010] Step three, perform photolithography and dry etching on the substrate with AlN buffer layer, wherein the AlN buffer layer in the area protected by photoresist remains intact, the AlN buffer layer in the area not covered by photoresist is completely removed, and finally an AlN buffer layer pattern is formed on the substrate;

[0011] Step four, put the substrate with the formed AlN buffer layer pattern back into the MOCVD reaction chamber, perform annealing treatment in H2 atmosphere first, and then perform ammoniation treatment in NH3 atmosphere, wherein the temperature is gradually increased from 1020 DEG C to 1060 DEG C during the ammoniation treatment;

[0012] Step five, grow AlN template layer on the substrate and the AlN buffer layer pattern to form a metal polarity and nitrogen polarity alternating growth structure, wherein the AlN template layer grown on the AlN buffer layer pattern has metal polarity, and the AlN template layer directly grown on the substrate has nitrogen polarity;

[0013] Step six, grow BN layer and BGaN layer on the AlN template in sequence to relieve stress and defects caused by lattice mismatch or thermal mismatch;

[0014] Step seven, grow AlGaN transition layer, AlGaN multiple quantum well layer and AlGaN protective layer on the BGaN layer in sequence to form a complete structure of light emitting diode epitaxial wafer.

[0015] Further, the substrate is a substrate suitable for epitaxial growth of sapphire, silicon, silicon carbide, gallium nitride and aluminum nitride.

[0016] Further, the growth temperature of the AlN buffer layer in step two is 550-700 DEG C, and the growth thickness is 15-30 nm.

[0017] Further, the AlN buffer layer pattern in step three is square, triangular or circular.

[0018] Further, the annealing treatment in step four is further:

[0019] controlling the temperature of the reaction chamber to be 1100-1200 DEG C, and annealing in H2 atmosphere for 4-10 min.

[0020] Further, the growth temperature of the AlN template layer in step five is 1200-1300 ℃, and the growth thickness is 1-3 um.

[0021] Further, the growth thickness of the BN layer in step six is 10-20 nm, and the thickness of the BGaN layer is 0.5-5 nm.

[0022] Compared with the prior art, the method for manufacturing the ultraviolet light emitting diode has the following beneficial effects:

[0023] 1. The AlN template layer is grown on the substrate and the AlN buffer layer to form a metal polarity and nitrogen polarity alternating growth structure, the polarization directions of the metal polarity and nitrogen polarity regions are opposite, and the directions of the energy band offset are opposite, due to the unique energy band structure, the carriers not only have longitudinal transmission and recombination in the quantum well based on the bipolar structure, but also have lateral migration of the carriers, the carriers have three-dimensional transmission and recombination on the nitrogen polarity surface, the carrier localization phenomenon is obvious, the quantum confinement Stark effect is weakened, the electron and hole radiation recombination rate is improved, and the internal quantum efficiency is improved. At the same time, the anti-phase boundaries in the crystal growth defects of the quantum well material will act as a radiation recombination center due to the particularity of the energy band structure, so that the light emission can be greatly enhanced. Compared with the traditional single polarity structure, the bipolar structure can greatly improve the light emission intensity of the light emitting diode.

[0024] 2. The substrate formed with the AlN buffer layer pattern is first subjected to annealing treatment in an H2 atmosphere, and then subjected to ammonization treatment in an NH3 atmosphere, the annealing treatment can promote the arrangement of atoms in the AlN material to be neat, which is beneficial to the subsequent material growth, the ammonization treatment can improve the quality of the nitrogen polarity crystal, promote the continuity at the material boundary, improve the lateral transmission of the carriers at the anti-phase boundaries, and then improve the electron-hole recombination probability, so that the LED light emission efficiency is improved. The temperature is gradually increased from 1020 ℃ to 1060 ℃ during the ammonization treatment process, which can ensure sufficient ammonization, promote the formation of the nitrogen polarity, avoid decomposition of the sapphire, improve the quality of the nitride thin film crystal, and enhance the antistatic ability.

[0025] 3. The BN layer and the BGaN layer are sequentially grown on the AlN template, the layers in the BN and BGaN material structure are combined by van der Waals force (similar to graphite and graphene), the interaction force between the atoms is small, the lattice matching needs not to be strictly followed, and the thermal conductivity is better, so that the stress and defects caused by the lattice mismatch or thermal mismatch can be relieved, the dislocations derived from the bottom layer are blocked, the dislocations derived from the bottom layer are reduced, the crystal quality is improved, the light emission efficiency of the LED is improved, and the antistatic ability is enhanced.

[0026] Of course, the implementation of any product of the present application does not necessarily require that all of the above-mentioned technical effects be achieved simultaneously.

[0027] Other features of the present application, its nature and advantages will become apparent from the accompanying detailed description of the exemplary embodiments of the application. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0029] Figure 1 The structure of the ultraviolet light emitting diode of the present application is shown.

[0030] Illustration: 1, substrate, 2, AlN buffer layer, 21, AlN buffer layer pattern, 3, AlN template layer, 4, BN layer, 5, BGaN layer, 6, AlGaN transition layer, 7, AlGaN multi-quantum well layer, 8, AlGaN protective layer. DETAILED DESCRIPTION

[0031] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of the components and steps set forth in the embodiments, numerical expressions, and numerical values, unless specifically stated otherwise, do not limit the scope of the present application.

[0032] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way limiting of the application or its applications or uses.

[0033] Techniques, methods, and apparatus known to those of ordinary skill in the relevant art can not be discussed in detail herein. However, where appropriate, such techniques, methods, and apparatus should be considered as being part of the specification.

[0034] In all of the examples shown and discussed herein, any specific values should be interpreted as merely illustrative and not as a limitation. Thus, other examples of the exemplary embodiments can have different values.

[0035] It should be noted that like references and characters herein relate to like items throughout the figures and the written description, and therefore, once an item is defined in one figure, it need not be discussed further in subsequent figures.

[0036] The method for manufacturing the ultraviolet light emitting diode described in the present embodiment includes the following steps:

[0037] Step 101, place the substrate 1 into the MOCVD reaction chamber for desorption treatment.

[0038] Step 102, control the temperature to be 550-700℃, and grow an AlN buffer layer 2 with a thickness of 15-30 nm on the substrate 1.

[0039] Step 103, perform photolithography and dry etching on the substrate with the AlN buffer layer 2, wherein the area protected by the photoresist keeps the AlN buffer layer intact, and the area not covered by the photoresist removes the AlN buffer layer completely, and finally form a square AlN buffer layer pattern 21 on the substrate.

[0040] Step 104, re-put the substrate 1 with the AlN buffer layer pattern 21 into the MOCVD reaction chamber, and perform annealing treatment in H2 atmosphere first, and then perform ammoniation treatment in NH3 atmosphere, wherein the temperature is gradually increased from 1020℃ to 1060℃ during the ammoniation treatment.

[0041] Further, the annealing treatment is:

[0042] Control the temperature of the reaction chamber to be 1100-1200℃, and anneal for 4-10 min in H2 atmosphere.

[0043] Step 105, control the temperature of the reaction chamber to be 1200-1300℃, and grow an AlN template layer 3 with a thickness of 1-3 um on the substrate 1 and the AlN buffer layer pattern 21 to form a metal polarity and nitrogen polarity alternating growth structure, wherein the AlN template layer 3 grown on the AlN buffer layer pattern 21 has metal polarity, and the AlN template layer 3 grown directly on the substrate 1 has nitrogen polarity.

[0044] Step 106, sequentially grow a BN layer 4 with a thickness of 10-20 nm and a BGaN layer 5 with a thickness of 0.5-5 nm on the AlN template 3 to relieve the stress and defects caused by lattice mismatch or thermal mismatch.

[0045] Step 107, sequentially grow an AlGaN transition layer 6, an AlGaN multi-quantum well layer 7, and an AlGaN protective layer 8 on the BGaN layer 5 to form a complete structure of a light-emitting diode epitaxial wafer, which improves the light-emitting intensity of the light-emitting diode by forming a metal polarity and nitrogen polarity alternating growth structure inside, and improves the material crystal quality by ammoniation treatment and introduction of the BN layer and the BGaN layer, further improves the light-emitting efficiency of the LED, and enhances the anti-static ability.

[0046] Although some specific embodiments of the present application have been described in detail by examples, those skilled in the art should understand that the above examples are only for illustration, but not for limiting the scope of the present application. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A method for fabricating a UV LED, comprising the following steps: Step 1: placing a substrate into a MOCVD reaction chamber for desorption treatment; Step 2: growing an AlN buffer layer on the substrate; Step 3: performing photolithography and dry etching on the substrate with the AlN buffer layer, wherein the AlN buffer layer in the area protected by photoresist remains intact, the AlN buffer layer in the area not covered by photoresist is completely removed, and finally an AlN buffer layer pattern is formed on the substrate; Step 4: placing the substrate with the AlN buffer layer pattern into the MOCVD reaction chamber again, performing annealing treatment in H2 atmosphere first, and then performing ammoniation treatment in NH3 atmosphere, wherein the temperature is gradually increased from 1020℃ to 1060℃ during the ammoniation treatment; Step 5: growing an AlN template layer on the substrate and the AlN buffer layer pattern to form a metal polarity and nitrogen polarity alternating growth structure, wherein the AlN template layer grown on the AlN buffer layer pattern has metal polarity, and the AlN template layer grown directly on the substrate has nitrogen polarity; Step 6: growing a BN layer and a BGaN layer on the AlN template in sequence to relieve stress and defects caused by lattice mismatch or thermal mismatch; Step 7: growing an AlGaN transition layer, an AlGaN multi-quantum well layer, and an AlGaN protective layer on the BGaN layer in sequence to form a complete structure of a light emitting diode epitaxial wafer.

2. The method of claim 1, wherein the method further comprises: The substrate is a substrate suitable for epitaxial growth, such as sapphire, silicon, silicon carbide, gallium nitride, and aluminum nitride.

3. The method of claim 1, wherein the method further comprises: The growth temperature of the AlN buffer layer in Step 2 is 550-700℃, and the growth thickness is 15-30nm.

4. The method of claim 1, wherein the method further comprises: The AlN buffer layer pattern in Step 3 is square, triangular, or circular.

5. The method of claim 1, wherein the method further comprises: The annealing treatment in Step 4 further comprises: controlling the temperature of the reaction chamber to 1100-1200℃, and annealing in H2 atmosphere for 4-10 min.

6. The method of claim 1, wherein the method further comprises: The growth temperature of the AlN template layer in Step 5 is 1200-1300℃, and the growth thickness is 1-3um.

7. The method of claim 1, wherein the method further comprises: forming a passivation layer on the UV-LED structure. The growth thickness of the BN layer in Step 6 is 10-20nm, and the thickness of the BGaN layer is 0.5-5nm.

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