Semiconductor crystal preparation method, seed crystal holder and PVT growth system

Abstract

The invention relates to a semiconductor crystal preparation method, a seed crystal holder and a PVT growth system. According to the method, on the basis of detecting a semiconductor crystal prepared by an existing process, the type and position of a defect are obtained, and then a temperature control groove is formed in a seed crystal support according to the type and position of the defect. Under the condition of high-temperature growth, the temperature control groove and the filler can cause the thermal radiation change of the position of the seed crystal support, so that the temperature near the adjacent seed crystals can be changed, and the thermal field distribution of the specific position of the growth surface of the seed crystals can be accurately regulated and controlled. Besides, a temperature control groove is formed in the back face of the seed crystal support, the structure and the manufacturing process are simple, and compared with the prior art, the cost is greatly reduced, that is, accurate control over thermal field distribution of the growth face of the seed crystal is achieved through low-cost improvement, and then the semiconductor crystal small in stress and low in defect density is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor crystal material preparation, and in particular to a semiconductor crystal preparation method, a seed crystal holder and a PVT growth system. Background Art

[0002] Silicon carbide (SiC), as a wide bandgap semiconductor crystal material after silicon (Si) and gallium arsenide (GaAs), has attracted much attention due to its excellent physical and chemical properties. These properties include a wide bandgap width, high critical breakdown electric field strength, excellent thermal conductivity, and excellent chemical stability. Therefore, the SiC single crystal material and its device industry have rapidly emerged and become a key strategic industry in the high-tech field. The preparation of large-size SiC single crystal substrates can not only significantly improve the manufacturing efficiency of SiC devices, but also significantly reduce their costs. These advances are of great significance to promoting the development of the SiC industry and promoting social progress.

[0003] At present, the most mature method for growing large-sized SiC single crystal substrate materials is the Physical Vapor Transport (PVT) method. Its basic principle is to heat SiC polycrystalline powder to above a certain temperature, and the SiC powder decomposes to produce a SiC atmosphere of specific components. The atmosphere is transmitted to the vicinity of the seed crystal with a relatively low temperature, and recrystallization occurs to obtain SiC single crystal materials of a specific shape. In order to obtain SiC single crystals with low defects and low stress, the growth interface in the early stage of growth is required to be a micro-convex interface, and the thermal field distribution (mainly radial temperature gradient) of the seed crystal growth surface in the early stage of growth determines the shape of the initial growth interface. Therefore, regulating the thermal field distribution of the initial seed crystal growth surface to obtain a micro-convex interface is the key to preparing high-quality SiC single crystals.

[0004] The current method usually uses seed crystal holders of different materials and shapes, or introduces hard felt, soft felt and other insulation materials with special structural designs near the seed crystal to regulate the thermal field distribution of the seed crystal growth surface. However, there are still some shortcomings: first, seed crystal holders of different shapes have a great influence on the overall thermal field distribution of the seed crystal growth surface, and it is difficult to achieve precise directional control of the thermal field at a specific position; second, the insulation materials of specific structures are complex to process, easy to wear and high in cost.

[0005] Therefore, it is of great significance to develop a simple, economical and efficient method to precisely and directionally control the thermal field distribution on the growth surface of the seed crystal. Summary of the invention

[0006] Based on this, it is necessary to provide a semiconductor crystal preparation method, a seed crystal holder and a PVT growth system to address the above problems, so as to achieve precise control of the thermal field distribution on the seed crystal growth surface through low-cost improvements, and then prepare semiconductor crystal materials with low defect density and low stress.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is: A method for preparing a semiconductor crystal, comprising: Preparation of semiconductor crystals using PVT growth system; Detecting the semiconductor crystal to obtain the defect type and position of the semiconductor crystal; According to the defect type and location, a temperature control groove is formed on the back of the seed crystal holder in the PVT growth system, and the temperature control groove is used to control the temperature of a specific location; Assembling a seed crystal holder provided with a temperature-controlled groove into a PVT growth system; The PVT growth system is used to prepare new semiconductor crystals.

[0008] The method for preparing semiconductor crystals disclosed in the present invention can obtain information such as the defect type and defect location of the prepared semiconductor crystal material by analyzing the semiconductor crystal material prepared by the prior art process, and make a temperature control groove on the back of the seed crystal holder in the PVT growth system to achieve precise control of the thermal field at a specific position. Finally, the defects of the prepared semiconductor crystal are eliminated by changing the thermal field at a specific position, thereby obtaining a semiconductor crystal with low defects. Compared with the prior art, it is achieved by reprocessing the seed crystal holder, and the structure and manufacturing process are simple, and the process cost is basically not increased. That is, the precise control of the thermal field distribution on the seed crystal growth surface is achieved through low-cost improvements, thereby obtaining a semiconductor crystal with low stress and low defect density.

[0009] In another embodiment, according to the defect type and location, the process of making a temperature control groove on the back side of the seed crystal holder in the PVT growth system includes: When the defect type of the semiconductor crystal is a concave macroscopic morphology, microcracks on the edge or high-temperature phase crystal defects, a temperature control groove is made at the position on the back of the seed crystal holder corresponding to the defect, and the temperature control groove is filled with solid material.

[0010] In another embodiment, according to the defect type and location, the process of making a temperature control groove on the back side of the seed crystal holder in the PVT growth system includes: When the defect type of the semiconductor crystal is a relatively convex macroscopic morphology or a low-temperature phase crystal defect exists at the edge, a temperature control groove is made at the position of the defect corresponding to the back of the seed crystal holder, and the temperature control groove is filled with gaseous material.

[0011] In another embodiment, according to the defect type and location, the process of making a temperature control groove on the back side of the seed crystal holder in the PVT growth system includes: When the defect type of the semiconductor crystal is a relatively concave macroscopic morphology, a temperature control groove is made at the edge of the back side of the seed crystal holder, and the temperature control groove is filled with a gaseous material; When the defect type of the semiconductor crystal is a relatively convex macroscopic morphology, a temperature control groove is made at the edge of the back side of the seed crystal holder, and the temperature control groove is filled with solid material.

[0012] In summary, the common semiconductor crystal defects are convex or concave macroscopic morphology, microcracks on the edge and crystal defects, and crystal defects are divided into low-temperature phase crystal defects and high-temperature phase crystal defects. In response to these common defects, the present invention adopts different temperature control methods, that is, when the defect type of the semiconductor crystal is concave macroscopic morphology, microcracks on the edge or high-temperature phase crystal defects, a temperature control groove is made at the position on the back of the seed crystal holder corresponding to the defect, and the temperature control groove is filled with solid material; when the defect type of the semiconductor crystal is convex macroscopic morphology or low-temperature phase crystal defects on the edge, a temperature control groove is made at the corresponding position on the back of the seed crystal holder, and the temperature control groove is filled with gaseous material. In addition to setting temperature control grooves at corresponding positions for temperature control, temperature control grooves can also be set at the edges around defects with convex or concave macroscopic morphology to perform reverse temperature control. That is, when the macroscopic morphology is more convex, temperature control grooves are set at the edges and filled with solid materials to accelerate the crystal growth rate at the edge; when the macroscopic morphology is more concave, temperature control grooves are set at the edges and filled with gaseous materials to slow down the crystal growth rate at the edge.

[0013] Through the above methods, different methods can be adopted to control the temperature of local micro-areas according to different defect types and locations, thereby reducing defects. Various methods of reducing defects are achieved by using different temperature control effects of the temperature control grooves on the seed crystal support.

[0014] In another embodiment, the gaseous material is argon, nitrogen, hydrogen or a mixture thereof.

[0015] In another embodiment, the solid material is tantalum carbide, tantalum, tungsten or hard felt.

[0016] In another embodiment, the cross-section of the temperature control groove is semicircular, rectangular or trapezoidal.

[0017] The above-mentioned different gaseous materials and solid materials, as well as the shape of the temperature control groove, are all set for fine control of the thermal field near the seed crystal growth surface. It is understandable that when the gaseous material is filled, the thermal field temperature of the corresponding seed crystal position will increase, which can not only slow down the growth rate of the crystal at the corresponding position, but also eliminate the low-temperature phase crystal defects. The gaseous material is further refined, and the precise control of the micro-area thermal field of the seed crystal growth surface at a specific position can be achieved, thereby obtaining semiconductor crystals with low stress and low defect density. When the solid material is filled, the thermal field temperature of the corresponding seed crystal position will decrease, which can not only accelerate the growth rate of the crystal at the corresponding position, but also eliminate edge microcracks and high-temperature phase crystal defects. The adjustment of the shape of the temperature control groove is also for the purpose of refining the temperature control effect.

[0018] That is, the present invention can adjust the thermal field over a larger range by setting temperature control grooves of different shapes and sizes at different positions, and by selecting to fill gaseous materials or solid materials. When it is necessary to adjust the micro-area thermal field at certain specific positions, temperature control grooves of special sizes and shapes can be set at the corresponding special positions, and different gaseous materials or solid materials can be filled to achieve precise directional control of the micro-area thermal field at the position.

[0019] In another embodiment, the semiconductor crystal is SiC, AlN or diamond.

[0020] Another embodiment of the present invention discloses a seed crystal holder, which is assembled in the PVT growth system. The PVT growth system is applied to the method for preparing semiconductor crystals described in any of the above embodiments. A temperature control groove is provided on the back of the seed crystal holder.

[0021] Yet another embodiment of the present invention discloses a PVT growth system, wherein the growth system is equipped with the seed crystal holder described in any of the above embodiments.

[0022] Beneficial effects: The method for preparing semiconductor crystals disclosed in the present invention can obtain information such as the defect type and defect location of the prepared semiconductor crystal material by analyzing the semiconductor crystal material prepared by the prior art process, and make a temperature control groove on the back of the seed crystal holder of the PVT growth system to achieve precise control of the thermal field at a specific position. Finally, the defects of the prepared semiconductor crystal are eliminated by changing the thermal field at a specific position, thereby obtaining a semiconductor crystal with low defects. Compared with the prior art, it is achieved by reprocessing the seed crystal holder, and the structure and manufacturing process are simple, and the process cost is basically not increased. That is, the precise control of the thermal field distribution on the seed crystal growth surface is achieved through low-cost improvements, thereby obtaining a semiconductor crystal with low stress and low defect density.

[0023] Moreover, by setting temperature control grooves of different shapes and sizes at different positions, and by choosing to fill them with gaseous materials or solid materials, the thermal field can be regulated over a larger range. When the thermal field of a micro-region at a certain specific position needs to be regulated, temperature control grooves of special sizes and shapes can be set at the corresponding special positions, and filled with different gases or solid materials, so as to achieve precise directional regulation of the thermal field of the micro-region at that position, thereby obtaining semiconductor crystal materials with fewer defects and better quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A cross-sectional schematic diagram of a seed crystal holder disclosed in an embodiment of the present invention; Figure 2 A cross-sectional schematic diagram of another seed crystal holder disclosed in an embodiment of the present invention; Figure 3 A cross-sectional schematic diagram of another seed crystal holder disclosed in an embodiment of the present invention; Figure 4 A schematic diagram of another combination of a seed crystal holder and a seed crystal disclosed in an embodiment of the present invention; Figure 5 A schematic diagram of another combination of a seed crystal holder and a seed crystal disclosed in an embodiment of the present invention; Figure 6 A schematic plan view of a seed crystal holder disclosed in an embodiment of the present invention; Figure 7 A schematic plan view of another seed crystal holder disclosed in an embodiment of the present invention; Figure 8 A schematic plan view of another seed crystal holder disclosed in an embodiment of the present invention; Fig. 9 A schematic plan view of another seed crystal holder disclosed in an embodiment of the present invention; Fig.10 It is a cross-sectional schematic diagram of another PVT growth system disclosed in an embodiment of the present invention.

[0025] In the figure: 1. seed crystal holder; 11. temperature control groove; 2. seed crystal; 3. crucible; 4. crucible cover. DETAILED DESCRIPTION

[0026] In order to facilitate understanding of the present invention, the present invention is described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to facilitate a more thorough and comprehensive understanding of the disclosure of the present invention.

[0027] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used in the present specification are for the convenience of clearly describing specific embodiments or examples, and are not intended to limit the present invention. The optional scope of the term "and / or" used herein includes not only any one of two or more listed related items, but also any and all combinations of the listed related items, including any combination of any two listed related items, any multiple listed related items, or all listed related items.

[0028] One embodiment of the present invention discloses a method for preparing a semiconductor crystal, comprising: Preparation of semiconductor crystals using PVT growth system; Detecting the semiconductor crystal to obtain the defect type and position of the semiconductor crystal; According to the defect type and location, a temperature control groove is formed on the back of the seed crystal holder of the PVT growth system, and the temperature control groove is used to control the temperature of a specific location; Assembling a seed crystal holder provided with a temperature-controlled groove into a PVT growth system; The PVT growth system is used to prepare new semiconductor crystals.

[0029] In this embodiment, the semiconductor crystal is SiC, AlN or diamond, and may also be other crystal materials that can be prepared using a PVT growth system.

[0030] The method for preparing semiconductor crystals disclosed in this embodiment can obtain information such as the defect type and defect location of the prepared semiconductor crystal material by analyzing the semiconductor crystal material prepared by the prior art process, and make a temperature control groove on the back of the seed crystal holder of the PVT growth system to achieve precise control of the thermal field at a specific position. Finally, the defects of the prepared semiconductor crystal are eliminated by changing the thermal field at a specific position, thereby obtaining a semiconductor crystal with low defects. Compared with the prior art, it is achieved by reprocessing the seed crystal holder, and the structure and manufacturing process are simple, and the process cost is basically not increased. That is, the precise control of the thermal field distribution on the seed crystal growth surface is achieved through low-cost improvements, thereby obtaining a semiconductor crystal with low stress and low defect density.

[0031] The study found that the defects of semiconductor crystal materials prepared by the existing PVT method can be divided into three categories: First, the macroscopic morphology of the crystal is convex or concave. The main reason is the uneven distribution of the radial temperature gradient of the seed crystal growth interface. When the edge temperature is too high and the temperature in the center is too low, the growth rate in the center will be much higher than that in the edge, and the macroscopic morphology of the output crystal will be convex; when the edge temperature is too low and the temperature in the center is too high, the growth rate in the center will be much lower than that in the edge, and the macroscopic morphology of the output crystal will be concave. Convex or concave crystal macroscopic morphology will lead to high crystal stress and defect density, increasing the risk of ingot splitting.

[0032] The second is the occurrence of multiple crystal defects, which mainly occur at the edge of the crystal. For example, when preparing SiC, in addition to 4H-SiC, multiple crystal forms such as 3C or 6H will also be produced. Among them, the 3C crystal form is a low-temperature phase crystal defect, which is caused by the local temperature being too low; the 6H crystal form is a high-temperature phase crystal defect, which is caused by the local temperature being too high.

[0033] Third, there are microcracks at the edge of the crystal. This defect is mostly caused by the edge temperature being too high, which causes the edge structure of the seed crystal to be destroyed, thus generating microcracks.

[0034] The causes of the above three types of defects are all related to the thermal field distribution in the local area of ​​the seed crystal growth interface. Based on this, the present invention effectively and accurately controls the thermal field distribution at a specific position of the seed crystal growth interface.

[0035] In one embodiment, according to the defect type and location, the process of making a temperature control groove on the back side of the seed crystal holder in the PVT growth system includes: When the defect type of the semiconductor crystal is a concave macroscopic morphology, microcracks on the edge or high-temperature phase crystal defects, a temperature control groove is made at the position on the back of the seed crystal holder corresponding to the defect, and the temperature control groove is filled with solid material.

[0036] Specifically, for defects with relatively concave macroscopic morphology, this embodiment introduces a temperature control groove at the position corresponding to the concave point, and the temperature control groove is filled with solid material. Since the solid material has a lower thermal conductivity, its radiation effect will cause the temperature of the seed crystal area at the position corresponding to the concave point to decrease, thereby increasing the growth rate of the semiconductor crystal at the position corresponding to the concave point, thereby eliminating the defects with relatively concave macroscopic morphology.

[0037] To address edge microcrack defects, a temperature control groove can be introduced at the corresponding position (generally near the edge of the seed crystal holder) and filled with solid material. The radiation effect of the solid material can lower the temperature of the seed crystal edge, reduce damage to the edge structure, and thus eliminate edge microcrack defects.

[0038] For high-temperature phase crystal defects, which usually occur at the edge of the crystal, the high-temperature phase crystal defects can be eliminated by lowering the temperature of the edge area of ​​the seed crystal. That is, by introducing a temperature control groove at the location of the high-temperature phase crystal defect (usually at the edge of the seed crystal), and filling the temperature control groove with solid materials, the temperature at the high-temperature phase crystal defect is lowered by the radiation of the solid materials, thereby eliminating the high-temperature phase crystal defect.

[0039] In another embodiment, according to the defect type and location, the process of making a temperature control groove on the back side of the seed crystal holder in the PVT growth system includes: When the defect type of the semiconductor crystal is a relatively convex macroscopic morphology or a low-temperature phase crystal defect exists at the edge, a temperature control groove is made at the position of the defect corresponding to the back of the seed crystal holder, and the temperature control groove is filled with gaseous material.

[0040] Specifically, for defects with relatively convex macroscopic morphology, this embodiment introduces a temperature control groove at the position corresponding to the bump, and the temperature control groove is filled with gaseous material. Since the gaseous material has a higher thermal conductivity, its radiation effect will cause the temperature of the seed crystal area at the position corresponding to the bump to increase, thereby reducing the growth rate of the semiconductor crystal at the position corresponding to the bump, thereby eliminating the defects with relatively convex macroscopic morphology.

[0041] Low-temperature phase crystal defects, which usually occur at the edge of the crystal, can be eliminated by increasing the temperature of the area corresponding to the low-temperature phase crystal defects (generally at the edge of the seed crystal). That is, by introducing a temperature control groove at the position corresponding to the low-temperature phase crystal defects, and the temperature control groove is filled with gaseous materials. Since the gaseous materials have a higher thermal conductivity, their radiation effect will cause the temperature of the corresponding seed crystal area to rise, thereby eliminating the low-temperature phase crystal defects.

[0042] In another embodiment, according to the defect type and location, the process of making a temperature control groove on the back side of the seed crystal holder in the PVT growth system includes: When the defect type of the semiconductor crystal is a relatively concave macroscopic morphology, a temperature control groove is made at the edge of the back side of the seed crystal holder, and the temperature control groove is filled with a gaseous material; When the defect type of the semiconductor crystal is a relatively convex macroscopic morphology, a temperature control groove is made at the edge of the back side of the seed crystal holder, and the temperature control groove is filled with solid material.

[0043] This embodiment is achieved by setting a temperature control groove at the edge of a defect with a relatively convex or concave macromorphology to perform reverse temperature control. That is, when the macromorphology is relatively convex, a temperature control groove is set at the edge and filled with solid materials to accelerate the crystal growth rate at the edge; when the macromorphology is relatively concave, a temperature control groove is set at the edge and filled with gaseous materials to slow down the crystal growth rate at the edge.

[0044] It should be noted that the location of the defect is generally caused by the uneven thermal field, and the thermal field distribution is different from the physical position of the seed crystal, that is, the center of the thermal field may not be the center of the seed crystal, or the edge of the thermal field may not be a strict edge area in the physical position of the seed crystal. The setting of the temperature control groove position in the above embodiment is set corresponding to the defect position. Therefore, the specific position of the temperature control groove can be the center, edge or middle transition area of ​​the seed crystal holder. The specific position is flexible and diverse, and no specific limitation is made here.

[0045] It can be seen from the above embodiments that the present invention can adopt different methods to accurately control the local temperature according to different defect types and locations. By setting different temperature control grooves on the seed crystal holder, different temperature control effects are produced, thereby achieving the goal of reducing or eliminating various types of crystal defects.

[0046] In another embodiment, the gaseous material is nitrogen, argon, hydrogen or a mixture thereof. That is, the processing and assembly of the temperature control groove of the seed crystal holder can be carried out in an atmosphere of nitrogen, argon, hydrogen or a mixture thereof.

[0047] In another embodiment, the solid material is tantalum carbide, tantalum, tungsten or hard felt, and can also be other solid materials that can cause thermal field changes, are resistant to high temperatures, are resistant to corrosion and have stable physical and chemical properties.

[0048] In another embodiment, the cross-sectional shape of the temperature control groove is semicircular, rectangular or trapezoidal, that is, the shape of the temperature control groove is controllable.

[0049] The above-mentioned different gaseous materials and solid materials, as well as the shape of the temperature control groove, are all set for fine control of the thermal field near the seed crystal growth surface. It is understandable that when the gaseous material is filled, the thermal field temperature of the corresponding seed crystal position will increase, which can eliminate the convex macroscopic morphology and low-temperature phase crystal defects at the corresponding position. Further refinement of the gaseous material can achieve precise control of the thermal field of the micro-area of ​​the seed crystal growth surface at a specific position, thereby obtaining semiconductor crystals with low stress and low defect density. When the solid material is filled, the thermal field temperature of the corresponding seed crystal position will decrease, which can eliminate the concave macroscopic morphology, edge microcracks and high-temperature phase crystal defects. The adjustment of the shape of the temperature control groove is also for the purpose of refining the temperature control effect.

[0050] In addition, considering that some defect problems may appear at the same time, for example, when the macroscopic morphology is relatively convex, edge microcracks and high-temperature phase crystal defects appear at the same time, the temperature control grooves can be directly set at the positions corresponding to the edge microcracks and high-temperature phase crystal defects and the positions of the relatively convex edges of the macroscopic morphology, that is, the temperature control grooves are basically distributed at the edge positions of the seed crystal holder. Moreover, when multiple temperature control grooves corresponding to defects are connected into a whole, it can be understood that one temperature control groove can solve the problems of relatively convex macroscopic morphology, edge microcracks and high-temperature phase crystal defects at the same time. In addition, the temperature control grooves can be set in a targeted manner according to the positions where the defects appear, that is, the corresponding defects are scattered and distributed.

[0051] At the same time. The present invention can adjust the thermal field over a larger range by setting temperature control grooves of different shapes and sizes at different positions, and by selecting filling gas or filling solid materials. When it is necessary to adjust the micro-area thermal field at certain specific positions, temperature control grooves of special sizes and shapes can be set at the corresponding special positions, and different gaseous materials or solid materials can be filled to achieve precise directional control of the micro-area thermal field at the position.

[0052] Another embodiment of the present invention discloses a seed crystal holder, such as Figure 1 As shown, a temperature control groove 11 is provided on the back of the seed crystal holder 1 .

[0053] The seed crystal holder disclosed in this embodiment introduces a temperature control groove on its back. Under high-temperature growth conditions, the temperature control groove and the filler will cause changes in the thermal radiation of the seed crystal holder at that location, which will in turn cause changes in the temperature near the adjacent seed crystals, thereby achieving precise control of the thermal field distribution at a specific location on the seed crystal growth surface. In addition, the temperature control groove set on the back of the seed crystal holder of the present invention has a simple structure and manufacturing process, and compared with the prior art, the cost is greatly reduced, that is, accurate control of the thermal field distribution on the seed crystal growth surface is achieved through low-cost improvements, thereby preparing a semiconductor crystal material with low defect density and low stress.

[0054] like Figure 1 As shown, the cross-sectional shape of the temperature control groove 11 disclosed in the above embodiment is a rectangle.

[0055] In another embodiment, the shape of the temperature control groove can be adjusted according to different product requirements, so the present invention does not specifically limit the specific shape of the temperature control groove. However, this embodiment also discloses several different shapes of temperature control grooves: the shape of the temperature control groove 11 can also be semicircular (such as Figure 2 ), or trapezoidal (as shown Figure 3 The above descriptions of the shapes of the temperature control groove 11 are only some commonly used ones. In addition, the shape of the temperature control groove 11 can also be prismatic, oblate or elliptical, or even a combination of two or more shapes.

[0056] In addition to the specific shape, such as Figure 4 As shown, the temperature control groove can be surrounded by the seed crystal holder 1 and the seed crystal 2 to form a closed cavity structure. Alternatively, the temperature control groove 11 can be opened in the form of an opening on the front or side of the seed crystal holder 1. Figure 5 shown.

[0057] In another embodiment, the position of the temperature control groove can also be adjusted according to different product requirements, so the present invention does not limit the specific position of the temperature control groove. However, this embodiment also discloses several temperature control grooves in different positions. Figure 6 As shown, a plurality of temperature control grooves 11 are distributed in a dot matrix on the back of the seed crystal holder 1. Figure 7 As shown, a single temperature control groove 11 is arranged at the center of the back side of the seed crystal holder 1. Figure 8 As shown, a plurality of temperature control grooves 11 are distributed in a ring shape on the back of the seed crystal holder 1. Fig. 9 As shown, an annular temperature control groove 11 is arranged on the back side of the seed crystal holder 1 .

[0058] In another embodiment, in addition to argon, the temperature control groove may also be filled with nitrogen, hydrogen or a mixture thereof and other gases that do not react with the seed crystal holder and the seed crystal. However, in addition to the filling gas, the temperature control groove may also be filled with solid materials. The solid material filled in the temperature control groove needs to meet the requirements of being able to cause thermal field changes, high temperature resistance, corrosion resistance, and stable physical and chemical properties. For example, in one embodiment, the solid material is tantalum carbide, tantalum, tungsten or hard felt.

[0059] It should be noted that temperature control grooves of different positions, shapes, sizes, and cross-sections and different gaseous materials or solid fillers will produce different thermal radiation changes, resulting in different effects on the thermal field distribution near adjacent seed crystals. In some cases, setting temperature control grooves of different sizes and positions, and filling differences in gaseous materials or solid materials will have a large difference in the impact on the thermal field distribution near adjacent seed crystals. In other cases, setting temperature control grooves of different sizes and positions, and filling different gaseous materials or different solid materials will produce smaller or even subtle differences in the impact on the temperature near adjacent seed crystals. Specifically, when we respond to different product requirements, we can control the thermal field from a larger range by setting temperature control grooves of different positions and sizes, and choosing to fill gaseous materials or solid materials. When it is necessary to regulate the thermal field of a micro-area at certain specific locations, it is possible to achieve precise directional regulation of the thermal field of the micro-area at that location by setting temperature control grooves of special sizes and shapes at the corresponding special locations, filling different gaseous materials or different solid materials.

[0060] In summary, the seed crystal holder disclosed in the embodiment of the present invention can not only adjust the thermal field on a macro scale, but also realize precise directional control of the thermal field in a micro area. That is, the seed crystal holder disclosed in the embodiment of the present invention can realize effective control of different thermal field scenarios through the special setting of the temperature control groove. At the same time, when nitrogen is selected as the gaseous filling material of the temperature control groove, the process cost can be minimized. In addition, when solid materials are selected for filling, it is only necessary to fit the shape of the temperature control groove. It is not required that the solid material must be a whole or that the solid material does not need to be complicatedly processed, etc., and the process cost is relatively low. Therefore, the seed crystal holder disclosed in the embodiment of the present invention can not only effectively control different thermal field scenarios, but also has a simple manufacturing process and relatively low process costs.

[0061] like Fig.10 As shown, another embodiment of the present invention further discloses a PVT growth system. The growth system includes a crucible 3, a seed crystal holder 1 arranged on the upper part of the crucible 3, and a crucible cover 4. The seed crystal holder 1 is the seed crystal holder disclosed in any of the above embodiments, and a seed crystal 2 is also bonded to the back of the seed crystal holder 1. Graphite paper or a metal compound is provided on the side of the seed crystal facing the seed crystal holder. When graphite paper is selected, the thickness of the graphite paper is 0.05 mm-5 mm. Specifically, the thickness of the graphite paper is 0.05 mm or 0.1 mm or 1 mm or 2.5 mm or 4 mm or 5 mm. When various types of metal compounds are selected, the metal compound can be a metal nitride, a metal boride or a metal carbide.

[0062] The PVT growth system disclosed in this embodiment can prepare semiconductor crystals such as SiC, AlN, and diamond by adjusting the types of seed crystals and raw materials. In the specific preparation process, the temperature control groove of the seed crystal holder 1 of the growth system can be used to accurately and directionally control the thermal field distribution at a specific position on the seed crystal growth surface to obtain high-quality products.

[0063] Moreover, the temperature control groove of the seed crystal holder of the PVT growth system of this embodiment has a simple structure and manufacturing process, and the cost is greatly reduced compared with the existing technology. That is, through low-cost improvements, precise control of the thermal field distribution on the seed crystal growth surface is achieved, and then semiconductor crystal materials with low defect density and low stress are prepared.

[0064] In another embodiment, a method for accurately controlling the thermal field distribution at a specific position of a seed crystal growth surface is disclosed, comprising the following steps: Design and processing of seed crystal support structure: Select materials of appropriate specifications, such as isostatic graphite, and design and process the seed crystal holder required for crystal growth. The back of the seed crystal holder (the surface close to the seed crystal) needs to ensure processing accuracy, especially without cutting marks. According to process requirements, a temperature control groove with a special structure is processed at a specific position of the seed crystal holder.

[0065] Seed crystal pretreatment: The seed crystal is pretreated using methods commonly used in the industry, including but not limited to introducing graphite paper on the side of the seed crystal facing the seed crystal holder, or forming a dense metal compound film layer such as metal nitride, metal boride and metal carbide on the side of the seed crystal facing the seed crystal holder.

[0066] Seed crystal holder and seed crystal assembly: Reasonably assemble the processed seed crystal holder and the pre-treated seed crystal. The reasonable assembly refers to assembling in a gaseous material atmosphere of argon, nitrogen, hydrogen or a mixture of these gases, or first filling the temperature control groove with solid materials such as tantalum carbide, tantalum, tungsten or hard felt, and then assembling the seed crystal holder and the seed crystal. Under high temperature conditions, the temperature control groove and the filler will cause changes in the thermal radiation of the seed crystal holder position, which will in turn cause changes in the temperature near the adjacent seed crystal, thereby achieving precise control of the thermal field at the corresponding position of the seed crystal growth surface. It should be noted that the radiation effect of the temperature control groove is applicable to situations where the seed crystal sticks to the holder or does not stick to the holder.

[0067] Another embodiment of the present invention simulates the distribution of the thermal field of the seed crystal by a temperature control groove with a rectangular cross section and a seed crystal holder filled with nitrogen. From the simulation results, it can be seen that the radiation effect of the temperature control groove and the gas filling will cause the temperature near the adjacent seed crystal to change, thereby achieving precise control of the thermal field distribution at a specific position on the growth surface of the seed crystal.

[0068] In another embodiment, the influence of the temperature control groove on the thermal field distribution at a specific position (here, the position 85 mm from the center of the seed crystal is selected for numerical simulation) is numerically simulated. From the simulation results, it can be seen that the thermal field at 85 mm from the center of the seed crystal has changed significantly, and the precise control of the thermal field at this position is achieved. In particular, this method is suitable for seed crystal support structures of different shapes.

[0069] In another embodiment, a defect with a relatively convex macroscopic morphology is analyzed, and the radial temperature gradient of the thermal field of the seed crystal with the defect can reach 32°C, while the radial temperature gradient of the thermal field of the seed crystal regulated by the temperature control groove is only 14°C.

[0070] Another embodiment of the present invention further discloses a method for preparing a SiC single crystal based on a PVT method, the method comprising: The SiC powder for preparing SiC single crystal is placed in the crucible of the PVT growth system. Under high temperature conditions, the SiC powder decomposes to produce a SiC atmosphere with a specific component, which is transmitted to the vicinity of the seed crystal with a relatively low temperature, where it recrystallizes and obtains a SiC crystal.

[0071] The SiC crystal is inspected by a series of inspection techniques to obtain the defect type and position of the SiC crystal.

[0072] According to the defect type and location, a temperature control groove is made on the back side of the seed crystal holder in the PVT growth system, and the temperature control groove is used to control the temperature of a specific location.

[0073] The seed crystal holder provided with the temperature-controlled groove is assembled into the PVT growth system.

[0074] The SiC powder for preparing SiC single crystal is placed in the crucible of the growth system again. Under high temperature conditions, the temperature control groove of the seed crystal holder will accurately control the thermal field of the nearby seed crystal as expected. At this time, the SiC powder decomposes to produce a SiC atmosphere of specific components, which is transmitted to the vicinity of the seed crystal with relatively low temperature, and recrystallization occurs. Since the micro-area thermal field can be precisely controlled, a micro-convex interface can be achieved at the growth interface in the early stage of SiC single crystal growth, and SiC single crystals with low defects and low stress can be further obtained.

[0075] The technical features of the above-mentioned embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. The "first" and "second" mentioned in the text are only for distinction and are not intended to limit the content of the present invention.

[0076] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a semiconductor crystal, characterized in that: include: Preparation of semiconductor crystals using PVT growth system; Detecting the semiconductor crystal to obtain the defect type and position of the semiconductor crystal; According to the defect type and location, a temperature control groove is formed on the back of the seed crystal holder in the PVT growth system, and the temperature control groove is used to control the temperature of a specific location; Assembling a seed crystal holder provided with a temperature-controlled groove into a PVT growth system; The PVT growth system is used to prepare new semiconductor crystals.

2. The preparation method according to claim 1, characterized in that: According to the defect type and location, the process of making a temperature control groove on the back side of the seed crystal holder in the PVT growth system includes: When the defect type of the semiconductor crystal is a concave macroscopic morphology, microcracks on the edge or high-temperature phase crystal defects, a temperature control groove is made at the position on the back of the seed crystal holder corresponding to the defect, and the temperature control groove is filled with solid material.

3. The preparation method according to claim 1, characterized in that: According to the defect type and location, the process of making a temperature control groove on the back side of the seed crystal holder in the PVT growth system includes: When the defect type of the semiconductor crystal is a relatively convex macroscopic morphology or a low-temperature phase crystal defect exists at the edge, a temperature control groove is made at the position of the defect corresponding to the back of the seed crystal holder, and the temperature control groove is filled with gaseous material.

4. The preparation method according to claim 1, characterized in that: According to the defect type and location, the process of making a temperature control groove on the back side of the seed crystal holder in the PVT growth system includes: When the defect type of the semiconductor crystal is a relatively concave macroscopic morphology, a temperature control groove is made at the edge of the back side of the seed crystal holder, and the temperature control groove is filled with a gaseous material; When the defect type of the semiconductor crystal is a relatively convex macroscopic morphology, a temperature control groove is made at the edge of the back side of the seed crystal holder, and the temperature control groove is filled with solid material.

5. The preparation method according to claim 2 or claim 4, characterized in that: The solid material is tantalum carbide, tantalum, tungsten or hard felt.

6. The preparation method according to claim 3 or claim 4, characterized in that: The gaseous material is argon, nitrogen, hydrogen or a mixed gas thereof.

7. The preparation method according to claim 1, characterized in that: The cross-section of the temperature control groove is in the shape of a semicircle, a rectangle or a trapezoid.

8. The preparation method according to claim 1, characterized in that: The semiconductor crystal is SiC, AlN or diamond.

9. A seed crystal holder, characterized in that: The seed crystal holder is assembled in the PVT growth system, and the PVT growth system is applied to the method for preparing a semiconductor crystal according to any one of claims 1 to 8, and a temperature control groove is arranged on the back of the seed crystal holder.

10. A PVT growth system, characterized in that: The growth system is equipped with the seed crystal holder according to claim 9.

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