Manufacturing method of ultraviolet light-emitting diode

Abstract

The invention discloses a method for manufacturing an ultraviolet light-emitting diode, which sequentially comprises the following steps of: performing desorption treatment on a substrate, growing an AlN buffer layer on the substrate, manufacturing an AlN buffer layer pattern, performing annealing treatment, performing 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 an AlGaN protective layer, and forming a light-emitting diode epitaxial wafer with a complete structure. The luminous intensity of the light-emitting diode is improved by forming a metal polarity and nitrogen polarity alternate growth structure in the LED, and meanwhile, the crystal quality of the material is improved by ammoniation treatment and introduction of the BN layer and the BGaN layer, so that the luminous efficiency of the LED is further improved, and the antistatic capability is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductors, and in particular relates to a method for manufacturing an ultraviolet light emitting diode. Background Art

[0002] Light-Emitting Diode (LED) is a semiconductor electronic device that converts electrical energy into light energy. As a new type of efficient, environmentally friendly, green solid-state lighting source, LED has been widely used in traffic lights, car lights, indoor and outdoor lighting, and display screens.

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

[0004] Ultraviolet LEDs are ideal candidates to replace traditional fragile and toxic UV mercury lamps due to their small size, long life, safety, reliability and pollution-free. Compared with blue and white LEDs, the photoelectric conversion efficiency of ultraviolet LEDs is still relatively low, and more efforts need to be made in related research. At present, ultraviolet LEDs still have problems such as high operating voltage, low quantum efficiency, and severe heat generation, which hinder their widespread application in daily life. The most important factor affecting the development of ultraviolet LEDs is their luminous efficiency. Compared with blue LEDs, the luminous efficiency of ultraviolet LEDs is very low. If their luminous efficiency can be improved, ultraviolet LEDs will have greater room for development.

[0005] Therefore, providing a method for manufacturing ultraviolet light emitting diodes to solve the problem of low luminous efficiency of existing ultraviolet LEDs and meet the application needs of ultraviolet LEDs is a technical problem that needs to be solved urgently in the technical field. Summary of the invention

[0006] The present invention improves the luminous intensity of the light-emitting diode by forming an alternating growth structure of metal polarity and nitrogen polarity inside the LED, and at the same time improves the crystal quality of the material through amination treatment and the introduction of BN layer and BGaN layer, thereby further improving the luminous efficiency of the LED and enhancing the antistatic ability.

[0007] The present invention discloses a method for manufacturing an ultraviolet light emitting diode, which is characterized by comprising the following steps:

[0008] Step 1: placing the substrate into a MOCVD reaction chamber for desorption treatment;

[0009] Step 2: growing an AlN buffer layer on the substrate;

[0010] Step 3, performing photolithography and dry etching on the substrate with the AlN buffer layer grown thereon, wherein the AlN buffer layer remains intact in the area protected by the photoresist, and the AlN buffer layer is completely removed in the area not covered by the photoresist, and finally an AlN buffer layer pattern is formed on the substrate;

[0011] Step 4: Place the substrate with the AlN buffer layer pattern back into the MOCVD reaction chamber for annealing in a H2 atmosphere, and then perform an ammoniation treatment in an NH3 atmosphere, wherein the temperature is gradually increased from 1020°C to 1060°C during the ammoniation treatment;

[0012] 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 directly grown on the substrate has nitrogen polarity;

[0013] Step 6: sequentially growing a BN layer and a BGaN layer on the AlN template to alleviate stress and defects caused by lattice mismatch or thermal mismatch;

[0014] Step 7: sequentially grow an AlGaN transition layer, an AlGaN multi-quantum well layer and an AlGaN protective layer on the BGaN layer to form a light-emitting diode epitaxial wafer with a complete structure.

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

[0016] Furthermore, the growth temperature of the AlN buffer layer in step 2 is 550-700° C., and the growth thickness is 15-30 nm.

[0017] Furthermore, the pattern of the AlN buffer layer in step three is square, triangle or circle.

[0018] Furthermore, the annealing treatment in step 4 is further performed as follows:

[0019] The temperature of the reaction chamber was controlled at 1100-1200°C and annealed in a H2 atmosphere for 4-10 minutes.

[0020] Furthermore, the growth temperature of the AlN template layer in step five is 1200-13000° C., and the growth thickness is 1-3 um.

[0021] Furthermore, 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 ultraviolet light emitting diodes of the present invention achieves the following beneficial effects:

[0023] 1. The present application grows an AlN template layer on a substrate and an AlN buffer layer to form an alternating growth structure of metal polarity and nitrogen polarity. Since the polarization directions of the metal polarity and nitrogen polarity regions are opposite, the directions of the energy band offset are opposite. Due to this unique energy band structure, carriers not only have longitudinal transmission and recombination in the quantum well based on the bipolar structure, but also have lateral migration of carriers. Carriers are three-dimensionally transmitted and recombinated on the nitrogen polarity surface, and the carrier localization phenomenon is obvious. The quantum confinement Stark effect is weakened, the radiation recombination rate of electrons and holes is improved, and the internal quantum efficiency is improved. At the same time, the anti-phase domain boundary in the crystal growth defect of the quantum well material will act as a radiation recombination center due to the particularity of the energy band structure, thereby greatly enhancing the luminescence. Compared with the traditional single polarity structure, the bipolar structure can greatly improve the luminescence intensity of the light-emitting diode.

[0024] 2. By first annealing the substrate with the AlN buffer layer pattern in a H2 atmosphere and then performing an amination treatment in an NH3 atmosphere, the annealing treatment can cause the atoms in the AlN material to be arranged neatly, which is beneficial to the subsequent material growth. The amination treatment can improve the quality of the nitrogen polar crystal, promote the continuity at the material boundary, and improve the lateral transmission of carriers at the antiphase domain boundary, thereby increasing the probability of electron-hole recombination and improving the luminous efficiency of the LED. During the amination treatment, the temperature is controlled to gradually increase from 1020°C to 1060°C, which can ensure sufficient amination, promote the formation of nitrogen polarity, and avoid decomposition of sapphire, which is beneficial to the improvement of the quality of the nitride film crystal and enhance the antistatic ability.

[0025] 3. By growing BN layers and BGaN layers on the AlN template in sequence, and utilizing the van der Waals force between layers in the BN and BGaN material structures (similar to graphite and graphene), the interaction force between atoms is small, and there is no need to strictly follow lattice matching. The thermal conductivity is better, which can alleviate the stress and defects caused by lattice mismatch or thermal mismatch, block the derivative of dislocations in the bottom layer, and reduce the dislocations derived from the bottom layer, thereby improving the crystal quality, and then improving the luminous efficiency of the LED, while enhancing the anti-static ability.

[0026] Of course, any product implementing the present invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0027] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] Figure 1 Shown is a structural diagram of an ultraviolet light emitting diode according to an embodiment of the present application.

[0030] Illustration description: 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 invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0032] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0033] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0034] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0035] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

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

[0037] Step 101: Place the substrate 1 into a MOCVD reaction chamber for desorption treatment.

[0038] Step 102, controlling the temperature to 550-700°C, growing an AlN buffer layer 2 with a thickness of 15-30 nm on the substrate 1.

[0039] Step 103, the substrate with the AlN buffer layer 2 is subjected to photolithography and dry etching, wherein the AlN buffer layer remains intact in the area protected by the photoresist, and the AlN buffer layer is completely removed in the area not covered by the photoresist, and finally a square AlN buffer layer pattern 21 is formed on the substrate.

[0040] Step 104, the substrate 1 with the AlN buffer layer pattern 21 formed thereon is placed back into the MOCVD reaction chamber for annealing treatment in H2 atmosphere, and then for ammoniation treatment in NH3 atmosphere, wherein the temperature is controlled to increase gradually from 1020° C. to 1060° C. during the ammoniation treatment;

[0041] Furthermore, the annealing treatment is:

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

[0043] Step 105, controlling the temperature of the reaction chamber to 1200-1300°C, growing 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 an alternating growth structure of metal polarity and nitrogen polarity, wherein the AlN template layer 3 grown on the AlN buffer layer pattern 21 has metal polarity, and the AlN template layer 3 directly grown on the substrate 1 has nitrogen polarity.

[0044] Step 106 : sequentially growing 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 stress and defects caused by lattice mismatch or thermal mismatch.

[0045] Step 107, an AlGaN transition layer 6, an AlGaN multi-quantum well layer 7 and an AlGaN protective layer 8 are sequentially grown on the BGaN layer 5 to form a fully structured light-emitting diode epitaxial wafer. The luminous intensity of the light-emitting diode is improved by forming an alternating growth structure of metal polarity and nitrogen polarity inside. At the same time, the crystal quality of the material is improved by ammoniation treatment and the introduction of BN layer and BGaN layer, thereby further improving the luminous efficiency of the LED and enhancing the antistatic ability.

[0046] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A method for manufacturing an ultraviolet light emitting diode, characterized in that it comprises the following steps: Step 1: placing the 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 grown thereon, wherein the AlN buffer layer remains intact in the area protected by the photoresist, and the AlN buffer layer is completely removed in the area not covered by the photoresist, and finally an AlN buffer layer pattern is formed on the substrate; Step 4: Place the substrate with the AlN buffer layer pattern back into the MOCVD reaction chamber for annealing in a H2 atmosphere, and then perform an ammoniation treatment in an NH3 atmosphere, wherein the temperature is gradually increased from 1020°C to 1060°C 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 directly grown on the substrate has nitrogen polarity; Step 6: sequentially growing a BN layer and a BGaN layer on the AlN template to alleviate stress and defects caused by lattice mismatch or thermal mismatch; Step 7: sequentially grow an AlGaN transition layer, an AlGaN multi-quantum well layer and an AlGaN protective layer on the BGaN layer to form a light-emitting diode epitaxial wafer with a complete structure.

2. The method for manufacturing an ultraviolet light emitting diode according to claim 1, characterized in that: The substrate is a substrate suitable for epitaxial growth of sapphire, silicon, silicon carbide, gallium nitride and aluminum nitride.

3. The method for manufacturing an ultraviolet light emitting diode according to claim 1, characterized in that: The growth temperature of the AlN buffer layer in step 2 is 550-700° C., and the growth thickness is 15-30 nm.

4. The method for manufacturing an ultraviolet light emitting diode according to claim 1, characterized in that: The pattern of the AlN buffer layer in step three is square, triangle or circle.

5. The method for manufacturing an ultraviolet light emitting diode according to claim 1, characterized in that: The annealing treatment in step 4 is further as follows: controlling the temperature of the reaction chamber to 1100-1200° C. and annealing in a H 2 atmosphere for 4-10 minutes.

6. The method for manufacturing an ultraviolet light emitting diode according to claim 1, characterized in that: The growth temperature of the AlN template layer in step five is 1200-13000° C., and the growth thickness is 1-3 um.

7. The method for manufacturing an ultraviolet light emitting diode according to claim 1, characterized in that: 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.

Images