Growth carrier plate of GaN thick film and preparation method of GaN thick film

Abstract

The invention provides a GaN thick film growth carrier plate and a GaN thick film preparation method, the growth carrier plate comprises a base and a surrounding edge surrounding the periphery of the base, the base and the surrounding edge are made of graphite materials, a groove used for placing a seed crystal is formed between the surrounding edge and the base, and the seed crystal is arranged in the groove. A lining layer is attached to the inner side wall of the surrounding edge, and the lining layer is resistant to corrosion of reaction gas used for growth of the GaN thick film. According to the GaN thick film growth carrier plate provided by the technical scheme of the invention, the corrosion-resistant lining layer is attached to the inner side wall of the surrounding edge of the base made of graphite, so that the influence of the graphite carrier plate on the growth quality of a gallium nitride wafer in a high-temperature and corrosive environment can be effectively avoided. According to the design, the growth rate of the large-thickness gallium nitride wafer is ensured, and meanwhile, the quality consistency of crystals at the edge and the center of the wafer is improved, so that the production requirement of the large-thickness gallium nitride wafer is met.

Description

Technical Field

[0001] The present invention relates to the technical field of GaN thick film growth, and in particular to a GaN thick film growth carrier and a GaN thick film preparation method. Background Art

[0002] Gallium nitride (GaN) is an important wide bandgap semiconductor material with excellent properties such as high electron mobility, high breakdown electric field and high thermal conductivity. It is widely used in high-frequency power devices, light-emitting diodes (LEDs) and lasers. In the growth of GaN wafers, chemical vapor deposition technology (CVD), especially hydride vapor phase epitaxy (HVPE) technology, has become one of the mainstream methods for the growth of GaN thick films due to its advantages of fast growth rate, low growth pressure and relatively low cost. In the existing technology, HVPE equipment is usually used to grow GaN wafers with a thickness of 200 to 800 μm to meet the market demand for medium-thick wafers.

[0003] With the continuous expansion of the application field of GaN devices, higher requirements are placed on the size and quality of GaN wafers. In actual production, the production efficiency of GaN wafers can be significantly improved by growing thicker GaN wafers and cutting them into multiple wafers. However, when growing thicker GaN wafers, some problems are exposed in the existing process and equipment design.

[0004] During the HVPE growth process, gallium nitride wafers are usually placed on a graphite carrier for epitaxial growth. Existing graphite carriers usually include a base and a surrounding edge surrounding the base, with a groove for placing the seed crystal formed between the surrounding edge and the base. When the wafer thickness is small, the heating rate at the edge and center of the wafer is relatively uniform, and the airflow distribution is relatively stable, so the quality consistency of the crystal on the same plane can be guaranteed. However, when the growth thickness of the gallium nitride wafer exceeds the height of the groove of the graphite carrier, the edge position of the wafer exceeds the protection range of the groove, and the heating rate and reaction airflow distribution change, resulting in a difference in the growth rate at the edge and center of the wafer. At the same time, the crystal quality at the edge of the wafer is more easily affected than the central area, and stress accumulation and increased defects may occur inside the crystal, thereby affecting the overall quality of the wafer.

[0005] In addition, as the thickness of the GaN wafer increases, the time required for growth also increases significantly. Under high temperature and corrosive atmosphere, the surface of the graphite carrier will be corroded by the reaction gas, especially the area where the graphite edge contacts the edge of the GaN wafer is more prone to chemical reaction. This corrosion will not only affect the service life of the carrier, but also have an adverse effect on the crystal quality of the edge of the wafer, further exacerbating the unevenness of the crystal quality of thick GaN wafers. Summary of the invention

[0006] The object of the present invention is to provide a GaN thick film growth carrier and a GaN thick film preparation method which can effectively prevent the growth of GaN thick film from being affected by the carrier edge effect.

[0007] In order to achieve the above-mentioned purpose, the present invention provides a GaN thick film growth carrier, which includes a base and a surrounding edge arranged around the base, the base and the surrounding edge are made of graphite material, a groove for placing a seed crystal is formed between the surrounding edge and the base, an inner lining layer is attached to the inner side wall of the surrounding edge, and the inner lining layer is resistant to corrosion by the reaction gas used for growing the GaN thick film.

[0008] Preferably, the surrounding edge is integrally formed with the base or is detachably connected to the base.

[0009] Preferably, the depth of the groove is 2 mm to 10 mm.

[0010] Preferably, the material of the lining layer is any one or more of silicon carbide, molybdenum, tungsten, titanium, niobium, vanadium, molybdenum carbide, tungsten carbide, titanium carbide, niobium carbide, vanadium carbide, and boron nitride.

[0011] Preferably, the lining layer is formed by chemical vapor deposition, chemical vapor reaction or liquid infiltration.

[0012] Preferably, a seed crystal substrate for carrying a seed crystal is also provided in the groove.

[0013] Preferably, the seed crystal substrate comprises a gallium nitride substrate or a sapphire substrate having a gallium nitride thin layer.

[0014] The present invention also provides a GaN thick film growth carrier, which includes a base and a surrounding edge arranged around the base, the base and the surrounding edge are made of graphite material, a groove for placing a seed crystal is formed between the surrounding edge and the base, the surrounding edge includes a first unit and a plurality of second units, the first unit is connected to the base, and the plurality of second units and the first unit can be stacked together through a detachable connection structure; the inner side walls of the first unit and the second unit are both attached with an inner lining layer, and the inner lining layer is resistant to corrosion by the reaction gas used for growing the GaN thick film.

[0015] Preferably, the first unit is integrally formed with the base or is detachably connected to the base.

[0016] Preferably, the enclosure height of any one of the first unit and the second unit is 0.5-3 mm.

[0017] Preferably, the material of the lining layer is any one or more of silicon carbide, molybdenum, tungsten, titanium, niobium, vanadium, molybdenum carbide, tungsten carbide, titanium carbide, niobium carbide, vanadium carbide, and boron nitride.

[0018] Preferably, the lining layer is formed by chemical vapor deposition, chemical vapor reaction or liquid infiltration.

[0019] The present invention also provides a method for preparing a GaN thick film, which comprises:

[0020] Providing a growth carrier as described above;

[0021] placing a seed crystal substrate in the groove formed by the first unit, and making the growth surface of the seed crystal substrate face away from the base;

[0022] placing the growth carrier into a HVPE device for GaN epitaxial growth;

[0023] When the thickness of the grown GaN single crystal layer approaches the top of the current groove, taking out the growth carrier from the HVPE device;

[0024] Adding a layer of the second unit on the growth carrier or replacing the second unit with another one having a target height;

[0025] Re-placing the growth carrier into the HVPE apparatus;

[0026] In this way, the second unit is added layer by layer until the thickness of the GaN single crystal layer meets the requirement.

[0027] Preferably, the heights of the second units added each time are the same or different.

[0028] Compared with the prior art, the GaN thick film growth carrier provided by the above technical solution of the present invention can effectively avoid the influence of the graphite carrier on the growth quality of gallium nitride wafers in high temperature and corrosive environments by attaching a corrosion-resistant lining layer to the inner side wall of the surrounding edge of the base made of graphite. This design helps to improve the consistency of crystal quality at the edge and center of the wafer while ensuring the growth rate of thick gallium nitride wafers, thereby meeting the production needs of thick gallium nitride wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 FIG. 1 is a plan view of the structure of a growth carrier in one embodiment of the present invention.

[0030] Figure 2 FIG. 4 is a plan view of the structure of a growth carrier in another embodiment of the present invention.

[0031] Figure 3 FIG. 1 is a plan view of the structure of a growth carrier when only the first unit is used in an embodiment of the present invention.

[0032] Figure 4This is a planar structural diagram of a growth carrier with a second unit added on top of the first unit in an embodiment of the invention.

[0033] Figure 5 This is a plan view of the structure of a growth carrier with two layers of second units added on the first unit in an embodiment of the invention.

[0034] Figure 6 This is a flow chart of a method for preparing a GaN thick film with increasing the height of the surrounding edge layer by layer in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to explain the technical content, structural features, achieved objectives and effects of the present invention in detail, the following is a detailed description in conjunction with the implementation methods and the accompanying drawings.

[0036] This embodiment discloses a GaN thick film growth carrier for use in HVPE equipment to grow gallium nitride wafers. Figure 1 The growth carrier includes a base 10 and a surrounding edge 11 arranged around the base 10, and the base 10 and the surrounding edge 11 are made of graphite material.

[0037] A groove 12 for placing a seed crystal is formed between the surrounding edge 11 and the base 10. An inner lining layer 13 is attached to the inner side wall of the surrounding edge 11. The inner lining layer 13 is resistant to corrosion by the reaction gas used for growing the GaN thick film.

[0038] Specifically, the lining layer 13 has excellent chemical stability, and exhibits extremely strong corrosion resistance and inertness. The lining layer 13 hardly reacts chemically with the reaction gases (NH, H) in the growth environment at high temperatures. Moreover, the lining layer 13 isolates the graphite disk from direct contact with the reaction gases, avoids the generation of byproducts by the graphite disk at high temperatures, and prevents them from diffusing to the edge of the gallium nitride wafer. In this embodiment, the material of the lining layer 13 is preferably any one or more of silicon carbide, molybdenum, tungsten, titanium, niobium, vanadium, molybdenum carbide, tungsten carbide, titanium carbide, niobium carbide, vanadium carbide, and boron nitride. Among them, when the lining layer 13 is made of boron nitride material, high-purity boron nitride (PBN) with a purity of more than 99.999% must be used.

[0039] On the other hand, the liner layer 13 is formed by a chemical vapor deposition method, a chemical vapor reaction method, or a liquid infiltration method.

[0040] It can be seen that by attaching the corrosion-resistant lining layer 13 on the inner wall of the peripheral edge 11 of the graphite base plate, the influence of high temperature and corrosive gas on the edge of the wafer can be effectively avoided, thereby reducing the growth rate difference between the edge and center of the wafer and ensuring the consistency of wafer quality.

[0041] In addition, the inner lining layer 13 can resist corrosion from the reaction gas, protect the graphite carrier, and reduce damage caused by chemical corrosion, thereby extending the service life of the carrier.

[0042] On the other hand, the surrounding edge 11 and the base 10 are integrally formed, which is convenient to use and does not require assembly.

[0043] The surrounding edge 11 and the base 10 may also be detachably connected, so that the base 10 may be provided with the surrounding edge 11 of different heights as required.

[0044] On the other hand, the depth of the groove 12 is 2 mm to 10 mm to meet the needs of producing gallium nitride wafers of different sizes and thicknesses.

[0045] On the other hand, a seed crystal substrate 14 for carrying a seed crystal is further disposed in the groove 12 .

[0046] Specifically, the seed crystal substrate 14 includes a gallium nitride substrate or a sapphire substrate with a gallium nitride thin layer.

[0047] In another preferred embodiment of the present invention, another GaN thick film growth carrier is disclosed, such as Figure 2 It includes a base 20 and a surrounding edge 21 arranged around the base 20. The base 20 and the surrounding edge 21 are made of graphite material. A groove 22 for placing a seed crystal is formed between the surrounding edge 21 and the base 20.

[0048] The surrounding edge 21 includes a first unit 210 and a plurality of second units 211 . The first unit 210 is connected to the base 20 . The plurality of second units 211 and the first unit 210 can be connected together in a stacked manner via a detachable connection structure.

[0049] Specifically, the first unit 211 is connected to any second unit 211 via a snap-fit ​​structure, and any two second units 211 are connected to each other via a snap-fit ​​structure.

[0050] The inner sidewalls of the first unit 210 and the second unit 211 are both attached with an inner liner layer 23 , and the inner liner layer 23 resists corrosion by the reaction gas used for growing the GaN thick film.

[0051] In this embodiment, the surrounding edge 21 has a building block-like stacked structure, such as Figure 2 , taking two second units 211a and 211b as an example, the first unit 210 is connected to the base 20. When the required wafer thickness is smaller than the height of the groove 22 enclosed by the first unit 210, as Figure 3 , there is no need to use two second units 211a, 211b.

[0052] like Figure 4 When the required wafer thickness is greater than the height of the groove 22 enclosed by the first unit 210 and less than the height of the groove 22 enclosed by the first unit 210 and the second unit 211a, the second unit 211a is mounted on the first unit 210.

[0053] Similarly, if Figure 5 When the required wafer thickness is greater than the height of the groove 22 formed by the first unit 210 and the second unit 211a, and less than the height of the groove 22 formed by the first unit 210, the second unit 211a, and the second unit 211b, the second unit 211a is sleeved on the first unit 210, and then the second unit 211b is sleeved on the second unit 211a.

[0054] In addition, the second unit 211 may be gradually added according to the growth of the GaN thick film.

[0055] Therefore, for the GaN thick film growth carrier in this embodiment, through the detachable stacked structure, the height of the surrounding edge 21 can be flexibly adjusted according to the required wafer thickness, to meet the growth requirements of GaN wafers of different thicknesses, thereby improving the versatility and adaptability of the equipment.

[0056] On the other hand, the first unit 210 is integrally formed with the base 20 or is detachably connected thereto.

[0057] The enclosure height of any one of the first unit 210 and the second unit 211 is 0.5 to 3 mm.

[0058] Similarly, the material of the lining layer 23 is any one or more of silicon carbide, molybdenum, tungsten, titanium, niobium, vanadium, molybdenum carbide, tungsten carbide, titanium carbide, niobium carbide, vanadium carbide, and boron nitride. Among them, when the lining layer 13 is made of boron nitride material, high-purity boron nitride (PBN) with a purity of more than 99.999% must be used. The lining layer 23 is formed by chemical vapor deposition, chemical vapor reaction, or liquid infiltration.

[0059] Based on the GaN thick film growth carrier with the stacked structure surrounding edge 21, another preferred embodiment of the present invention further discloses a GaN thick film preparation method, such as Figure 6 , which includes the following processes:

[0060] S10: placing the seed crystal substrate 24 in the groove 22 formed by the first unit 210, and making the growth surface of the seed crystal substrate 24 face away from the base 20. It should be noted that in this process, only the first unit 210 is installed above the base 20, and no second unit 211 is installed.

[0061] S11: placing the growth carrier into the HVPE equipment for GaN epitaxial growth, wherein the growth temperature in the furnace of the HVPE equipment is controlled to be 800-1100° C., the pressure to be 100-600 torr, and the growth rate to be 20-100 um / h.

[0062] S12: When the thickness of the grown GaN single crystal layer approaches the top of the current groove 22, the growth carrier is taken out from the HVPE device, and the currently generated GaN single crystal layer and the seed crystal substrate 24 are cleaned. The cleaning can be performed by combining organic solvent cleaning and acid cleaning.

[0063] S13: Determine whether the GaN single crystal layer has grown to the target thickness. If yes, end the process. If no, execute S14.

[0064] S14: adding a layer of second unit 211 on the growth carrier or replacing another second unit 211 with a target height (greater than the height of the current second unit 211), and returning to step S11.

[0065] For the GaN thick film preparation method disclosed in this embodiment, first, by increasing the height of the surrounding edge 21 layer by layer, the problem of gas flow obstruction or turbulence caused by the surrounding edge 21 being too high in the early stage of GaN crystal growth is avoided, thereby ensuring that the reaction gas is uniformly deposited on the seed crystal substrate 24, improving the quality and growth rate stability of the GaN crystal, and reducing the generation of defects.

[0066] Secondly, under high temperature conditions, when the crystal thickness increases, cracks or defects are easily generated inside the crystal due to the accumulation of thermal stress. Gradually increasing the height of the surrounding edge 21 and growing the crystal thickness in stages can effectively alleviate the concentrated effect of thermal stress, make the crystal structure more complete, and reduce the cracks, warping and dislocation density caused by stress.

[0067] In addition, in HVPE equipment, if the height of the surrounding edge 21 is too high, it may change the thermal field distribution in the furnace, resulting in an increase in the temperature difference between the growth center and the edge of the wafer, causing uneven thickness and stress concentration. In this embodiment, the height of the surrounding edge 21 is gradually increased to always adapt to the current thickness of the wafer, reducing the disturbance of the surrounding edge 21 to the thermal field, thereby achieving more uniform thick film growth.

[0068] Therefore, as GaN thick film applications develop towards large-sized wafers (such as 6-inch and 8-inch), the method of gradually increasing the height of the surrounding edge 21 is particularly suitable for the step-by-step growth of large-sized wafers. It can more effectively solve the problems of stress accumulation and uneven airflow distribution when the thickness increases, and provides a reliable technical path for the preparation of high-performance large-sized GaN wafers.

[0069] On the other hand, the height of the second unit 211 added each time is the same. For example, to grow a 10 mm GaN single crystal layer, the second unit 211 is added 2 mm each time, and then grown 5 times in total.

[0070] On the other hand, the height of the second unit 211 added each time can also be different. For example: to grow a 10mm GaN single crystal layer, the height of the second unit 211 is 0.2-1mm for the first time, 3mm for the second time, 2mm for the third time, 2mm for the fourth time, and 1-2mm for the fifth time. That is, the growth thickness of the GaN single crystal layer each time is 0.2-1mm, 3mm, 2mm, and 1-1.2mm, respectively. The first growth of a smaller thickness is to check the initial growth quality of the GaN single crystal layer. If the growth quality is qualified, consider continuing the thick film growth. If it does not meet the requirements for continuing the thick film growth, it will be processed as a conventional product.

[0071] For another example, to grow a 10 mm GaN single crystal layer, the heights of the second unit 211 that are gradually increased are: 3 mm, 2.5 mm, 2 mm, 1.5 mm, and 1 mm. This method assumes that the seed crystal substrate 24 is of high quality, the grown GaN single crystal layer has few defects, and the growth quality is qualified, but it is necessary to consider that as the growth thickness increases, the growth stress increases, and the thickness of the subsequent single growth is appropriately reduced.

[0072] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope covered by the present invention.

Claims

1. A GaN thick film growth carrier, characterized in that: The invention comprises a base and a surrounding edge arranged around the base, wherein the base and the surrounding edge are made of graphite material, a groove for placing a seed crystal is formed between the surrounding edge and the base, an inner lining layer is attached to the inner side wall of the surrounding edge, and the inner lining layer is resistant to corrosion by the reaction gas used for growing GaN thick films.

2. The GaN thick film growth carrier according to claim 1, characterized in that: The surrounding edge is integrally formed with the base or is detachably connected to the base.

3. The GaN thick film growth carrier according to claim 1, characterized in that: The depth of the groove is 2 mm to 10 mm.

4. The GaN thick film growth carrier according to claim 1, characterized in that: The material of the lining layer is any one or more of silicon carbide, molybdenum, tungsten, titanium, niobium, vanadium, molybdenum carbide, tungsten carbide, titanium carbide, niobium carbide, vanadium carbide, and boron nitride.

5. The GaN thick film growth carrier according to claim 1, characterized in that: The liner layer is formed by chemical vapor deposition, chemical vapor reaction or liquid infiltration.

6. The GaN thick film growth carrier according to claim 1, characterized in that: A seed crystal substrate for carrying a seed crystal is also arranged in the groove.

7. The GaN thick film growth carrier according to claim 6, characterized in that: The seed crystal substrate includes a gallium nitride substrate or a sapphire substrate with a gallium nitride thin layer.

8. A GaN thick film growth carrier, characterized in that: The invention comprises a base and a surrounding edge arranged around the base, wherein the base and the surrounding edge are made of graphite material, a groove for placing a seed crystal is formed between the surrounding edge and the base, and the surrounding edge comprises a first unit and a plurality of second units, wherein the first unit is connected to the base, and the plurality of second units and the first unit can be stacked together through a detachable connection structure; an inner lining layer is attached to the inner side walls of the first unit and the second unit, and the inner lining layer is resistant to corrosion by the reaction gas used for growing GaN thick films.

9. The GaN thick film growth carrier according to claim 8, characterized in that: The first unit is integrally formed with the base or is detachably connected to the base.

10. The GaN thick film growth carrier according to claim 8, characterized in that: The enclosure height of any one of the first unit and the second unit is 0.5 to 3 mm.

11. The GaN thick film growth carrier according to claim 8, characterized in that: The material of the lining layer is any one or more of silicon carbide, molybdenum, tungsten, titanium, niobium, vanadium, molybdenum carbide, tungsten carbide, titanium carbide, niobium carbide, and vanadium carbide.

12. The GaN thick film growth carrier according to claim 8, characterized in that: The liner layer is formed by chemical vapor deposition, chemical vapor reaction or liquid infiltration.

13. A method for preparing a GaN thick film, characterized in that: include: Providing a growth carrier according to any one of claims 8 to 12; placing a seed crystal substrate in the groove formed by the first unit, and making the growth surface of the seed crystal substrate face away from the base; placing the growth carrier into a HVPE device for GaN epitaxial growth; When the thickness of the grown GaN single crystal layer approaches the top of the current groove, taking out the growth carrier from the HVPE device; Adding a layer of the second unit on the growth carrier or replacing the second unit with another one having a target height; Re-placing the growth carrier into the HVPE apparatus; In this way, the second unit is added layer by layer until the thickness of the GaN single crystal layer meets the requirement.

14. The method for preparing a GaN thick film according to claim 13, characterized in that: The height of the second unit added each time may be the same or different.

Images