A method for growing a thick film of GaN with reduced surface particles

Abstract

The present application relates to a kind of GaN thick film growth method for reducing surface particles.The method includes the following steps: (1) ammonia is introduced, under the protection of ammonia, to the temperature of GaN thick film growth temperature;(2) grow GaN thick film on the sapphire substrate with GaN seed crystal, then introduce etching raw material, remove polycrystalline GaN particles on the tray while growing GaN thick film, and obtain GaN thick film.The present application introduces etching raw material when starting to grow GaN thick film until the end of GaN thick film growth or intermittently introduces etching raw material during GaN thick film growth, which can avoid growing polycrystalline GaN on the tray, or remove polycrystalline GaN that has already grown on the tray, directly avoid and reduce polycrystalline GaN particles on the tray falling on the wafer during thick film GaN growth, achieve the number of polycrystalline GaN particles on the surface of GaN thick film <5, and successfully prepare the GaN thick film with smooth and bright surface.

Description

TECHNICAL FIELD

[0001] The present application relates to a GaN thick film growth method for reducing surface particles, and belongs to the field of optoelectronic power devices. BACKGROUND

[0002] GaN material is an ideal material for making optoelectronic devices, especially blue-green light LED and LD. Such light sources have broad application prospects and huge market potential in high-density optical information storage, high-speed laser printing, full-color dynamic high-brightness light display, solid-state lighting light source, high-brightness signal detection, communication, etc. In addition, GaN semiconductor material is also an ideal material for making high-temperature, high-frequency and high-power devices. GaN is a representative of nitride materials, and is one of the excellent wide-bandgap III-V compound semiconductor materials, and is one of the advanced semiconductor materials in the world today.

[0003] At present, GaN material is mainly prepared by hydride vapor phase epitaxy (HVPE) or metal organic chemical vapor deposition (MOVCD), and sapphire is used as a substrate to directly epitaxially grow GaN thick film on the sapphire substrate. In the existing growth device, the sapphire substrate is generally located on a graphite tray coated with a silicon carbide coating. During the growth of GaN thick film, GaN not only grows on the substrate, but also grows on the graphite tray. When the GaN on the graphite tray grows to a certain thickness, polycrystalline GaN will be formed and fall off, resulting in a large number of polycrystalline GaN particles falling on the epitaxial wafer, and thus the epitaxial wafer is scrapped and cannot be used. In view of this, the present application provides a GaN thick film growth method for reducing surface particles. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a GaN thick film growth method for reducing surface particles. During the growth of thick film GaN, etching raw materials are introduced to remove polycrystalline GaN on the tray, thereby reducing the falling of polycrystalline particles on the epitaxial wafer during the growth of thick film GaN, solving the problem of falling particles during the growth of thick film GaN, providing thick film for the preparation of GaN self-supporting substrate, and being applied to homoepitaxial power devices, blue laser, etc., to meet the application requirements of high-efficiency new-type high-power power electronics, optoelectronics, etc.

[0005] The technical scheme of the present application is as follows:

[0006] A GaN thick film growth method for reducing surface particles, comprising the following steps:

[0007] (1) introducing ammonia, and heating to the GaN thick film growth temperature under the protection of ammonia;

[0008] (2) A GaN thick film is grown on a sapphire substrate with GaN seed crystals by metal-organic chemical vapor deposition or hydride vapor phase epitaxy. Then, an etchable raw material is introduced to remove the polycrystalline GaN particles on the tray while growing the GaN thick film to obtain the GaN thick film.

[0009] According to a preferred embodiment of the present invention, in step (1), the ammonia flow rate is 10-100L and the growth temperature is 1050-1150℃.

[0010] According to a preferred embodiment of the present invention, in step (2), the thickness of the GaN seed crystal growth is 0.5-5 μm.

[0011] According to a preferred embodiment of the present invention, in step (2), when using metal-organic chemical vapor deposition, the growth pressure is controlled between 20 and 300 mbar, and the V / III ratio is controlled between 150 and 1500.

[0012] According to a preferred embodiment of the present invention, in step (2), when using hydride vapor phase epitaxy, the growth pressure is controlled between 500 and 1000 mbar, and the V / III ratio is controlled between 20 and 200.

[0013] According to a preferred embodiment of the present invention, in step (2), the timing of introducing the etchable material is: introducing the etchable material at the beginning of GaN thick film growth until the end of GaN thick film growth, or introducing the etchable material intermittently during GaN thick film growth.

[0014] In a further preferred embodiment, an etchant is introduced every 2-20 μm of GaN thick film growth for 2-5 minutes, forming a periodic cycle until the GaN thick film growth is complete.

[0015] According to a preferred embodiment of the present invention, in step (2), the etching raw material is carbon tetrachloride, carbon tetrabromide, hydrogen chloride or chlorine, and the amount introduced is 5000-10000 mol.

[0016] More preferably, in step (2), the etching raw material is carbon tetrachloride, and the amount introduced is 6000-9000 mol.

[0017] Under these conditions, the etchant has minimal impact on the GaN growth rate and can remove GaN polycrystalline particles from graphite trays with silicon carbide coatings. Although the etchant will react with some of the raw materials used for GaN growth, this invention fully considers the impact of the etchant on the growth raw materials, and the above method will not affect the GaN and crystal quality on the sapphire substrate.

[0018] According to a preferred embodiment of the present invention, in step (2), the thickness of the GaN thick film is 300-600 μm.

[0019] Furthermore, the growth method of this invention will not adversely affect other processes, such as subsequent laser ablation and other related processes. Where this invention is not exhaustive, existing technologies can be employed.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. This invention provides a method for growing GaN thick films with reduced surface particles. By introducing an etchant material at the beginning of GaN thick film growth until the end of GaN thick film growth, or by intermittently introducing the etchant material during GaN thick film growth, polycrystalline GaN can be avoided growing on the tray, or the polycrystalline GaN already grown on the tray can be removed. This directly avoids and reduces the number of polycrystalline GaN particles on the tray falling onto the epitaxial wafer during the thick film GaN growth process, achieving a number of polycrystalline GaN particles on the GaN thick film surface of <5, and successfully preparing a GaN thick film with a smooth and bright surface.

[0022] 2. The unique feature of the growth method provided by this invention is that it uses an etchable raw material to etch away the polycrystalline GaN with poor crystal quality on the tray. The etched polycrystalline material enters the tail gas end with the gas flow in the reaction chamber. However, for the growing GaN thick film, its crystal quality is good and its bonding ability with the substrate is strong. The etchable raw material has almost no effect on it and it is not etched. This solves the problem of particle falling off during the growth of GaN thick film, effectively improves the quality and yield of GaN thick film, provides thick film for the preparation of GaN self-supporting substrates, and can be applied to power devices, blue lasers, etc. of homoepitaxial growth, meeting the application needs of high-efficiency new high-power power electronics, optoelectronics and other fields. Attached Figure Description

[0023] Figure 1 This is a diagram showing the physical composition of the GaN thick film of the present invention.

[0024] In the diagram: the arrows represent the raw material gas for GaN growth and the etching raw material gas. Detailed Implementation

[0025] To make the technical problems, technical solutions and advantages of the present invention clearer, the present invention will be further described below through embodiments and in conjunction with the accompanying drawings. However, the present invention is not limited thereto. All matters not described in detail in the present invention are based on conventional techniques in the art.

[0026] Example 1

[0027] A method for growing GaN thick films with reduced surface particles, such as Figure 1 As shown, the steps are as follows:

[0028] (1) Introduce 50L of ammonia gas and heat it to 1100℃ under the protection of ammonia gas;

[0029] (2) A GaN thick film was grown on a sapphire substrate with a 3μm thick GaN seed crystal by metal-organic chemical vapor deposition. At the same time, 8000mol of carbon tetrachloride was introduced to remove polycrystalline GaN particles on the tray while growing the GaN thick film, resulting in a bright GaN thick film.

[0030] Among them, the growth pressure of the metal-organic chemical vapor deposition method is 200 mbar and the V / III ratio is 800.

[0031] Example 2

[0032] A method for growing GaN thick films with reduced surface particles includes the following steps:

[0033] (1) Introduce 80L of ammonia gas and raise the temperature to 1100℃ under the protection of ammonia gas;

[0034] (2) A GaN thick film was grown on a sapphire substrate with a GaN seed crystal of 3 μm thickness by metal-organic chemical vapor deposition. For every 10 μm of GaN thick film growth, an etching material was introduced once for 3 min. A total of 7000 mol of carbon tetrachloride was introduced to obtain a bright GaN thick film.

[0035] Among them, the growth pressure of the metal-organic chemical vapor deposition method is 200 mbar and the V / III ratio is 800.

[0036] Example 3

[0037] A method for growing GaN thick films with reduced surface particles includes the following steps:

[0038] (1) Introduce 10L of ammonia gas and raise the temperature to 1050℃ under the protection of ammonia gas;

[0039] (2) A GaN thick film was grown on a sapphire substrate with a GaN seed crystal of 0.5 μm thickness by metal-organic chemical vapor deposition. At the same time, 5000 mol of carbon tetrachloride was introduced to remove polycrystalline GaN particles on the tray while growing the GaN thick film, resulting in a bright GaN thick film.

[0040] The growth pressure for the metal-organic chemical vapor deposition method is 20 mbar, and the V / III ratio is 150.

[0041] Example 4

[0042] A method for growing GaN thick films with reduced surface particles includes the following steps:

[0043] (1) Introduce 100L of ammonia gas and raise the temperature to 1150℃ under the protection of ammonia gas;

[0044] (2) A GaN thick film was grown on a sapphire substrate with a 5μm thick GaN seed crystal by metal-organic chemical vapor deposition. At the same time, 10000mol of carbon tetrachloride was introduced to remove polycrystalline GaN particles on the tray while growing the GaN thick film, resulting in a bright GaN thick film.

[0045] Among them, the growth pressure of the metal-organic chemical vapor deposition method is 300 mbar and the V / III ratio is 1500.

[0046] Example 5

[0047] A method for growing GaN thick films with reduced surface particles includes the following steps:

[0048] (1) Introduce 60L of ammonia gas and heat it to 1100℃ under the protection of ammonia gas;

[0049] (2) A GaN thick film was grown on a sapphire substrate with a 2μm thick GaN seed crystal by hydride vapor phase epitaxy. At the same time, 6000mol of carbon tetrachloride was introduced to remove polycrystalline GaN particles on the tray while growing the GaN thick film, resulting in a bright GaN thick film.

[0050] Among them, the hydride vapor phase epitaxy method has a growth pressure of 800 mbar and a V / III ratio of 50.

[0051] Example 6

[0052] A method for growing GaN thick films with reduced surface particles, the steps are the same as those described in Example 1, except that the etchant material introduced is carbon tetrabromide.

[0053] Example 7

[0054] A method for growing GaN thick films with reduced surface particles, the steps are the same as those described in Example 1, except that the etchant material introduced is hydrogen chloride.

[0055] Comparative Example 1

[0056] A method for growing GaN thick films includes the following steps:

[0057] (1) Introduce 50L of ammonia gas and heat it to 1100℃ under the protection of ammonia gas;

[0058] (2) A GaN thick film was grown on a sapphire substrate with a GaN seed crystal of 3 μm thickness by means of metal-organic chemical vapor deposition.

[0059] Among them, the growth pressure of the metal-organic chemical vapor deposition method is 200 mbar and the V / III ratio is 800.

[0060] Test case

[0061] Using the methods of Example 2 and Comparative Example 1 of the present invention, GaN thick films with thicknesses of 300 μm, 400 μm, 500 μm, and 600 μm were grown, respectively. Ten samples were grown for each thickness, and the particle composition on the surface of the GaN thick films was statistically analyzed. The specific results are shown in Table 1.

[0062] Table 1: Statistical Table of Particle Status on GaN Thick Film Surface

[0063]

[0064] As shown in Table 1, the method of this invention can achieve a particle-free surface for 300μm and 400μm GaN thick films, and for 500μm and 600μm GaN thick films, the number of surface particles is less than 3. In contrast, the method of Comparative Example 1 results in GaN thick films with more than 80 surface particles, and the number of surface particles increases with thickness and growth time. This indicates that the method of this invention can avoid growing polycrystalline GaN on the tray, or remove the polycrystalline GaN already grown on the tray, directly preventing and reducing the number of polycrystalline GaN particles falling onto the epitaxial wafer during the thick film GaN growth process. This achieves a GaN thick film surface with less than 5 polycrystalline GaN particles, successfully preparing a smooth and bright GaN thick film. This solves the problem of particle falling during GaN thick film growth, effectively improving the quality and yield of GaN thick films, providing thick films for the preparation of GaN self-supporting substrates, and applying them to power devices and blue lasers using homoepitaxial growth, meeting the application needs of high-efficiency, novel high-power power electronics, optoelectronics, and other fields.

Claims

1. A method for growing GaN thick films with reduced surface particles, characterized in that, The steps include the following: (1) Introduce ammonia gas and, under the protection of ammonia gas, raise the temperature to the GaN thick film growth temperature; (2) A GaN thick film is grown on a sapphire substrate with GaN seed crystals by metal-organic chemical vapor deposition or hydride vapor phase epitaxy. Then, an etchable raw material is introduced to remove the polycrystalline GaN particles on the tray while growing the GaN thick film to obtain the GaN thick film. The timing of introducing the etchant is as follows: the etchant is introduced at the beginning of GaN thick film growth until the end of GaN thick film growth, or intermittently during GaN thick film growth. Furthermore, the etchant is introduced once every 2-20 μm of GaN thick film growth, with a duration of 2-5 minutes, forming a periodic cycle until the end of GaN thick film growth. The etchant is carbon tetrachloride, carbon tetrabromide, hydrogen chloride, or chlorine gas, and the amount introduced is 5000-10000 mol.

2. The GaN thick film growth method for reducing surface particles as described in claim 1, characterized in that, In step (1), the ammonia flow rate is 10-100L and the growth temperature is 1050-1150℃.

3. The GaN thick film growth method for reducing surface particles as described in claim 1, characterized in that, In step (2), the thickness of the GaN seed crystal growth is 0.5-5 μm.

4. The GaN thick film growth method for reducing surface particles as described in claim 1, characterized in that, In step (2), when using metal-organic chemical vapor deposition, the growth pressure is controlled between 20 and 300 mbar, and the V / III ratio is controlled between 150 and 1500.

5. The GaN thick film growth method for reducing surface particles as described in claim 1, characterized in that, In step (2), when using hydride vapor phase epitaxy, the growth pressure is controlled between 500 and 1000 mbar, and the V / III ratio is controlled between 20 and 200.

6. The GaN thick film growth method for reducing surface particles as described in claim 1, characterized in that, In step (2), the etching raw material is carbon tetrachloride, and the amount introduced is 6000-9000 mol.

7. The GaN thick film growth method for reducing surface particles as described in claim 1, characterized in that, In step (2), the thickness of the GaN thick film is 300-600 μm.

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