Substrate table and substrate growth method

Abstract

The invention relates to a substrate table and a substrate growth method, the substrate table is used for accommodating a substrate, and the substrate table comprises a base and at least one cover plate; the base is provided with at least one first concave cavity, and the side wall of the first concave cavity is provided with a part abutting against the substrate; at least one through hole is formed in each cover plate, the cover plates are matched with the base in a replaceable mode, and the thicknesses of different cover plates are different; when the cover plate is matched with the base, the projection of the first concave cavity is located in the projection edge of the through hole, and the upper surface of the cover plate is higher than the upper surface of the substrate. In the growth process of the substrate, the cover plates with different thicknesses are replaced according to the growth stage of the substrate, so that the upper surface of the replaced cover plate is higher than the upper surface of the substrate. The semi-closed space for accommodating the substrate is formed through the matching structure of the first concave cavity and the through hole, and the thickness of the cover plate can be adjusted according to the growth stage of the substrate, so that the growth state of the substrate is improved, and the growth quality of the substrate is improved.

Description

Technical Field

[0001] The present application relates to the technical field of substrate stages, and in particular to a substrate stage and a substrate growth method. Background Art

[0002] In recent years, single crystal diamond has attracted extensive attention in the field of cutting-edge semiconductors due to its excellent performance and good development prospects in many aspects. The growth of high-quality single crystal diamond has become the main direction for the application of diamond materials, and the growth technology of high-quality single crystal diamond has also become a research hotspot in the current field of diamond material technology. Microwave Plasma Chemical Vapor Deposition (MPCVD) technology is currently the most ideal method for preparing high-quality CVD single crystal diamond. In the process of MPCVD method for depositing and growing single crystal diamond, the substrate stage structure used and the growth method used have an important influence on its growth rate and high quality.

[0003] At present, most of the substrate stage structures used in microwave plasma chemical vapor deposition (MPCVD) technology are still traditional open platform structures, which is mainly to improve the diamond deposition rate. However, in the open platform structure substrate stage, the diamond seed crystal is directly placed on the substrate stage plane. Plasma usually gathers at the edge of the seed crystal, thereby generating a higher concentration of growth groups, a higher growth temperature and a higher growth rate at the edge. Due to the "edge effect" of plasma microwave discharge during the deposition process, the surface temperature of the diamond seed crystal gradually decreases from the edge to the center. The temperature difference on the surface of the seed crystal leads to poor surface flatness of the growing diamond, and "polycrystalline rings", defects and residual stress appear on the edge of the seed crystal, thereby hindering the high-quality growth of single crystal diamond. In addition, the diamond seed crystal placed on the open platform structure substrate stage is easily disturbed by the gas in the cavity during the deposition process and moves, resulting in low growth efficiency. Summary of the invention

[0004] In response to the above technical problems, the present application provides a substrate stage and a substrate growth method, which can improve the growth state of the substrate and enhance the growth quality of the substrate.

[0005] In a first aspect, in order to solve the above technical problems, the present application provides a substrate stage for accommodating a substrate, comprising a base and at least one cover plate;

[0006] The base is provided with at least one first concave cavity, and the side wall of the first concave cavity has a portion abutting against the substrate; the cover plate is provided with at least one through hole, and the cover plate can be replaceably matched with the base, and the thickness of different cover plates is different; when the cover plate is matched with the base, the projection of the first concave cavity is located inside the projection edge of the through hole, and the upper surface of the cover plate is higher than the upper surface of the substrate.

[0007] In one embodiment, the longitudinal section of the first cavity is rectangular, a second cavity is disposed on the bottom surface of the first cavity, and an opening area of ​​the second cavity is smaller than an opening area of ​​the first cavity.

[0008] In one embodiment, the opening of the first cavity and the opening of the second cavity are both circular, the substrate is rectangular, the diameter of the first cavity matches the diagonal length of the substrate, and the diameter of the second cavity is less than or equal to the side length of the substrate.

[0009] In one embodiment, the longitudinal section of the first cavity is trapezoidal, the opening area of ​​the first cavity is larger than the bottom area of ​​the first cavity, the opening and the bottom of the first cavity are both circular, the substrate is rectangular, the diameter of the opening of the first cavity is larger than the diagonal length of the substrate, and the diameter of the bottom of the first cavity is smaller than the diagonal length of the substrate.

[0010] In one embodiment, when the cover plate is matched with the base, a height difference between an upper surface of the cover plate and an upper surface of the substrate is 1.0 mm to 1.8 mm.

[0011] In one embodiment, the difference between the diameter of the through hole and the diameter of the first cavity is 1.6 mm to 3 mm.

[0012] In one embodiment, the base is provided with a first limiting portion, and the cover is provided with a second limiting portion, and when the cover is matched with the base, the first limiting portion matches the second limiting portion.

[0013] In one embodiment, the first limiting portion is an annular groove disposed along the upper edge of the base, and the second limiting portion is an annular convex edge disposed along the lower edge of the cover plate.

[0014] In one embodiment, at least one limiting boss is provided on the annular groove, and at least one limiting recess is provided on the annular convex edge. When the cover plate is matched with the base, the limiting boss matches with the limiting recess.

[0015] In one embodiment, the first limiting portion is an annular convex edge provided along the upper edge of the base, and the second limiting portion is an annular groove provided along the lower edge of the cover plate.

[0016] In a second aspect, the present application further provides a substrate growth method, using the substrate stage as shown above, comprising the following steps:

[0017] S1. Providing a substrate stage as described in the first aspect;

[0018] Placing a substrate in a first concave cavity of a base of the substrate stage, wherein a side wall of the first concave cavity at least partially abuts against the substrate;

[0019] S2. A cover plate is placed on top of the base, wherein the projection of the first cavity is located inside the projection edge of the through hole on the cover plate, and the upper surface of the cover plate is higher than the upper surface of the substrate;

[0020] S3. growing the substrate;

[0021] S4. According to the growth stage of the substrate, the cover plate of different thicknesses is replaced so that the upper surface of the replaced cover plate is higher than the upper surface of the substrate;

[0022] S5. When the growth thickness of the substrate reaches a preset value, stop the growth of the substrate.

[0023] In one embodiment, after the step S5, the method further comprises:

[0024] The substrate stage is subjected to a stepwise cooling and heat preservation treatment to complete the growth of the substrate.

[0025] In one embodiment, before the step S3, the method further comprises:

[0026] Place the substrate stage into the MPCVD device, set the microwave power of the MPCVD device to 30KW-40KW, and the cavity pressure to 10Kpa-15Kpa;

[0027] A process gas is introduced to grow the substrate.

[0028] The substrate stage and substrate growth method of the present application, the substrate stage is used to accommodate the substrate, including a base and at least one cover plate; the base is provided with at least one first concave cavity, the side wall of the first concave cavity has a portion abutting against the substrate; the cover plate is provided with at least one through hole, the cover plate can be replaced to match with the base, and the thickness of different cover plates is different; when the cover plate matches with the base, the projection of the first concave cavity is located inside the projection edge of the through hole, and the upper surface of the cover plate is higher than the upper surface of the substrate. The substrate growth method includes: after placing the substrate in the first concave cavity, covering the base with a cover plate, the upper surface of the cover plate is higher than the upper surface of the substrate; introducing process gas to make the substrate grow; according to the growth stage of the substrate, replacing the cover plate of different thicknesses, so that the upper surface of the replaced cover plate is higher than the upper surface of the substrate; when the growth thickness of the substrate reaches a preset value, stop introducing process gas. The present application forms a semi-enclosed space for accommodating the substrate through the matching structure of the first cavity and the through hole, and can adjust the thickness of the cover plate according to the growth stage of the substrate, thereby improving the growth state of the substrate and improving the growth quality of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of a substrate stage according to an embodiment of the present application;

[0030] Figure 2 is a schematic structural diagram of a base according to an embodiment of the present application;

[0031] Figure 3 is a schematic structural diagram of a cover plate according to an embodiment of the present application;

[0032] Figure 4 is a cross-sectional schematic diagram of a substrate stage according to an embodiment of the present application;

[0033] Figure 5 is a partial cross-sectional schematic diagram of a substrate stage according to an embodiment of the present application;

[0034] Figure 6 is a schematic flow chart of a substrate growth method according to an embodiment of the present application;

[0035] Figure 7 is one of the top views of the cover plate shown according to the embodiment of the present application;

[0036] Figure 8 is a second top view of a cover plate according to an embodiment of the present application;

[0037] Fig. 9 is a substrate growth comparison diagram shown according to an embodiment of the present application;

[0038] Fig.10 This is a third top view of the cover plate shown according to the embodiment of the present application. DETAILED DESCRIPTION

[0039] The following is an explanation of the implementation of the present application by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification.

[0040] In the following description, reference is made to the accompanying drawings, which describe several embodiments of the present application. It should be understood that other embodiments may be used and that mechanical, structural, electrical, and operational changes may be made without departing from the spirit and scope of the present application. The following detailed description should not be considered limiting, and the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0041] Although the terms first, second, etc. are used herein to describe various elements in some instances, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element.

[0042] Furthermore, as used in this article, the singular forms "one", "an" and "the" are intended to include plural forms as well, unless there is an indication to the contrary in the context. It should be further understood that the terms "comprise", "include" indicate the presence of the described features, steps, operations, elements, components, projects, kinds, and / or groups, but do not exclude the presence, occurrence or addition of one or more other features, steps, operations, elements, components, projects, kinds, and / or groups. The terms "or" and "and / or" used herein are interpreted as inclusive, or mean any one or any combination. Therefore, "A, B or C" or "A, B and / or C" means "any of the following: A; B; C; A and B; A and C; B and C; A, B and C". Exceptions to this definition will only occur when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way.

[0043] First embodiment

[0044] Figure 1 It is a schematic diagram of the structure of a substrate stage according to an embodiment of the present application. Figure 2 It is a schematic diagram of the structure of a base according to an embodiment of the present application. Figure 3 is a schematic diagram of the structure of the cover plate according to an embodiment of the present application. Figures 1 to 3 As shown, the substrate stage is used to accommodate a substrate 30 , and includes a base 10 and at least one cover plate 20 .

[0045] The base 10 is provided with at least one first cavity 11, and the side wall of the first cavity 11 has a portion abutting against the substrate 30. The cover plate 20 is provided with at least one through hole 21, and the cover plate 20 is replaceably matched with the base 10, and different cover plates 20 have different thicknesses. When the cover plate 20 is matched with the base 10, the projection of the first cavity 11 is located inside the projection edge of the through hole 21, and the upper surface of the cover plate 20 is higher than the upper surface of the substrate 30.

[0046] In this embodiment, the substrate 30 (such as a diamond seed crystal) is placed in the first cavity 11, and the substrate 30 abuts against the side wall of the first cavity 11. The side wall of the first cavity 11 limits the substrate 30, thereby solving the problem of movement of the diamond seed crystal in the open substrate table structure due to the disturbance of the cavity airflow.

[0047] The substrate stage includes a base 10 and a cover plate 20. At different stages of the substrate growth process, multiple cover plates 20 with different thicknesses are used to ensure that the upper surface of the cover plate 20 is always higher than the upper surface of the substrate 30 during the growth process of the substrate 30. When the cover plate 20 cooperates with the base 10, the cover plate 20 is stacked on the base 10, and the projection of the first cavity 11 is located inside the projection edge of the through hole 21, that is, the area of ​​the through hole 21 is larger than the opening area of ​​the first cavity 11. In this way, by replacing the cover plate during the growth process to adapt to the growth stage of the substrate, the upper surface of the cover plate is always higher than the upper surface of the substrate, the semi-enclosed space state around the substrate is maintained, and the plasma distribution around the diamond seed crystal is improved, thereby improving the growth state of the single crystal diamond and improving the growth quality.

[0048] Preferably, the diameter of the through hole 21 can be set to be 1.6mm to 3mm larger than the diameter of the first cavity 11. The depth of the through hole 21 is designed according to the thickness of the substrate 30 (generally 300 to 500um thick) and the depth of the first cavity 11 (generally 150um to 200um): through hole depth H (mm) = diamond seed crystal thickness (mm) - first cavity 11 depth (mm) + (1.0 to 1.8mm), so that the upper surface of the diamond seed crystal is 1.0mm to 1.8mm lower than the upper surface of the cover plate 20. In this way, the substrate 30 is placed in a semi-enclosed space, and the edge effect can be avoided during the growth of the substrate 30, and the gas flow field distribution around the substrate 30 is improved.

[0049] It should be noted that the diamond seed crystal is a small piece of natural diamond crystal, usually extracted from natural diamond ore. The surface of these small crystals has a diamond lattice structure, which can be used as a seed to guide the growth of new diamond crystals during the synthesis process. In the process of homoepitaxial growth of diamonds by diamond seed crystals, the distribution of gas flow fields such as methane and hydrogen will affect the surface growth state. In the traditional open substrate stage structure, the gas flow field flows through the edge of the diamond seed crystal, and the density will increase, that is, the "edge effect". The substrate stage structure used in this application can be understood as a diamond seed crystal embedded in a groove, the surface of the diamond seed crystal is lower than the upper surface of the cover plate 20, and the inner wall of the through hole 21 surrounds the diamond seed crystal. At the same time, the diameter and depth of the through hole 21 determine the spatial position of the diamond seed crystal during the growth process. The spatial position relationship will change the gas flow field distribution, thereby improving the surface plasma density distribution of the diamond seed crystal.

[0050] In one embodiment, the base 10 is a metal molybdenum machined structural part with a surface roughness Ra≤3.2um, so that the substrate 30 is in full contact with the base 10, improving the thermal conductivity of the substrate stage. The base 10 is cylindrical in shape, with a diameter of φ75mm to φ125mm and a height of 5 to 10mm.

[0051] In one embodiment, the base 10 is provided with a first limiting portion 13, and the cover plate 20 is provided with a second limiting portion 22. When the cover plate 20 is matched with the base 10, the first limiting portion 13 matches the second limiting portion 22. In this way, the first limiting portion 13 and the second limiting portion 22 cooperate to form a limiting structure, which facilitates the installation between the base 10 and the cover plate 20 and improves the stability of the substrate stage.

[0052] like Figure 2 and Figure 3 As shown, the first limiting portion 13 is an annular groove 13 provided along the upper edge of the base 10, and the second limiting portion 22 is an annular convex edge 22 provided along the lower edge of the cover plate 20. At least one limiting boss 131 is provided on the annular groove 13, and at least one limiting recess 221 is provided on the annular convex edge 22. When the cover plate 20 is matched with the base 10, the limiting boss 131 matches the limiting recess 221. In this way, the annular groove 13 and the annular convex edge 22 form a matching structure, and the limiting boss 131 and the limiting recess 221 form a matching structure, which facilitates the installation between the base 10 and the cover plate 20, and further improves the overall stability of the substrate stage.

[0053] Preferably, the width of the annular groove 13 can be set to 2 mm to 3 mm, and the height can be set to 1.5 mm to 2 mm. The length of the limiting boss 131 is about 2 mm, and its height is consistent with the annular groove 13. Correspondingly, the width of the annular convex edge 22 can be set to 2 mm to 3 mm, and the height can be set to 1.5 mm to 2 mm. The length of the limiting recess 221 is about 2 mm, and its height is consistent with the annular convex edge 22.

[0054] In one embodiment, the first limiting portion 13 may also be an annular convex edge provided along the upper edge of the base 10, and the second limiting portion 22 may be an annular groove provided along the lower edge of the cover plate 20. In this way, the annular convex edge of the base 10 and the annular groove of the cover plate 20 form a matching limiting structure. Similarly, at least one limiting notch may be provided on the annular convex edge, and at least one limiting boss may be provided at a corresponding position on the annular groove to improve the stability of the substrate stage.

[0055] In one embodiment, the longitudinal section of the first cavity 11 is rectangular, and the second cavity 12 is disposed on the bottom surface of the first cavity 11 . The opening area of ​​the second cavity 12 is smaller than the opening area of ​​the first cavity 11 .

[0056] In one embodiment, the opening of the first cavity 11 and the opening of the second cavity 12 are both circular, the substrate 30 is rectangular, the diameter of the first cavity 11 matches the diagonal length of the substrate 30, and the diameter of the second cavity 12 is less than or equal to the side length of the substrate 30.

[0057] like Figure 4 and Figure 5 As shown, the base 10 is evenly distributed with a plurality of first concave cavities 11 for placing the substrate 30, the cover plate 20 has the same diameter as the base 10, and the first concave cavities 11 and the second concave cavities 12 form a concentric circle structure. The design of the second concave cavity 12 allows the four corners of the substrate 30 to be suspended on the first concave cavity 11, which improves the surface temperature uniformity of the diamond seed crystal and improves the quality of diamond growth. The design of the first concave cavity 11 allows the four corners of the substrate 30 to contact and limit with the side wall of the first concave cavity 11, solving the problem of the movement of the diamond seed crystal due to the disturbance of the cavity airflow in the open substrate stage structure.

[0058] It should be noted that the open platform structure in the prior art is that the diamond seed crystal is directly placed on the platform, that is, there is no second cavity at the bottom. In this case, the surface temperature distribution of the diamond seed crystal is that the edge temperature is greater than the center temperature, which is caused by the flow direction of the airflow and the edge effect of the plasma ball. The present application sets a second cavity 12 as the second cavity on the base 10 at the bottom of the substrate 30, and the heat of the edge of the substrate 30 can be quickly exported to the substrate stage through the contact between the edge of the substrate 30 and the first cavity 11, and then exported to the copper stage (not shown) at the bottom of the substrate stage for water cooling and heat dissipation, thereby solving the problem that the edge temperature of the diamond seed crystal is greater than the center temperature.

[0059] Preferably, the size of the first cavity 11 is set according to the diagonal length of the substrate 30. For example, if the side length of the substrate 30 is 3*3mm, 5*5mm, 7*7mm, 10*10mm, 15*15mm, the diameter of the first cavity 11 is set to φ4.25mm, φ7.08mm, φ9.90mm, φ14.15mm, φ21.22mm. The depth of the first cavity 11 is set to 150um to 200um according to the thickness of the substrate 30 (generally 300 to 500um thick). This design allows the bottom position of the substrate 30 to be inserted into the first cavity 11, so that the bottom of the four corners of the substrate 30 is in contact with the first cavity 11, thereby playing a role in limiting the diamond seed crystal.

[0060] Preferably, the size of the second cavity 12 is set according to the diagonal length of the substrate 30. For example, if the side length of the substrate 30 is 3*3mm, 5*5mm, 7*7mm, 10*10mm, 15*15mm, the diameter of the second cavity 12 is set to φ3mm, φ5mm, φ7mm, φ10mm, φ15mm. The depth of the second cavity 12 is set to 30um~150um. The diameter of the second cavity 12 is designed to be consistent with the side length of the substrate 30, so as to achieve the surface temperature uniformity effect of the diamond seed crystal. When the diamond seed crystal is placed in the first cavity 11, it completely covers the second cavity 12, and contacts the inner wall of the first cavity 11 through the four corners, so as to achieve the limitation and surface heat uniformity of the diamond seed crystal.

[0061] like Figure 5 As shown, a diagonal cross-sectional view of a single substrate 30 is used to further illustrate that the substrate 30 is placed in the first cavity 11 on the base 10 through four corner contacts, and a second cavity 12 for heat dissipation is provided below the substrate 30. The cover plate 20 is stacked and placed on the base 10, and the relative spatial position relationship between the through hole 21 of the cover plate 20 and the diamond seed crystal of the substrate 30 is reflected in: there is a certain distance between the substrate 30 and the inner wall of the through hole 21; there is a certain distance between the upper surface of the substrate 30 and the upper surface of the through hole 21 of the cover plate 20. The semi-enclosed space formed in this way can greatly improve the plasma distribution around the substrate, thereby improving the growth state of single crystal diamond and improving the growth quality.

[0062] In one embodiment, the longitudinal section of the first cavity 11 may also be trapezoidal, the opening area of ​​the first cavity 11 is larger than the bottom area of ​​the first cavity 11, the opening and bottom of the first cavity 11 are both circular, the substrate 30 is rectangular, the diameter of the opening of the first cavity 11 is larger than the diagonal length of the substrate 30, and the diameter of the bottom of the first cavity 11 is smaller than the diagonal length of the substrate 30. In this way, the four corners of the substrate 30 are abutted against the side wall of the first cavity 11 for limiting, and the heat generated during the growth of the substrate 30 can be quickly discharged through the side wall of the first cavity 11 and the space below, thereby improving the surface temperature uniformity of the diamond seed crystal.

[0063] The substrate stage of the embodiment of the present application is used to accommodate the substrate, and includes a base and at least one cover plate; the base is provided with at least one first concave cavity, and the side wall of the first concave cavity has a portion that abuts against the substrate; the cover plate is provided with at least one through hole, and the cover plate can be replaced to match the base, and different cover plates have different thicknesses; when the cover plate matches the base, the projection of the first concave cavity is located inside the projection edge of the through hole, and the upper surface of the cover plate is higher than the upper surface of the substrate. The present application forms a semi-enclosed space for accommodating the substrate through the matching structure of the first concave cavity and the through hole, and adjusts the thickness of the cover plate according to the growth stage of the substrate, thereby improving the growth state of the substrate and improving the growth quality of the substrate.

[0064] Second embodiment

[0065] Figure 6 FIG. 1 is a schematic diagram of a growth method of a substrate according to an embodiment of the present application. Figure 6 As shown, the substrate growth method of the present application uses the substrate stage of the first embodiment, and includes the following steps:

[0066] S1. Providing a substrate stage as described in the first embodiment;

[0067] A substrate is placed in the first cavity of the base of the substrate stage, and a side wall of the first cavity at least partially abuts against the substrate.

[0068] Determine the substrate stage with the appropriate diameter size according to the performance of the MPCVD equipment. Select the corresponding base and corresponding multiple cover plates according to the size and thickness of the substrate (diamond seed crystal). Then select the same batch of diamond seed crystals with the same size and the same number of first cavities, and perform acid washing on the diamond seed crystals to remove the metal particles and organic residues on their surfaces.

[0069] S2. Cover the base with a cover plate, wherein the projection of the first cavity is located inside the projection edge of the through hole on the cover plate, and the upper surface of the cover plate is higher than the upper surface of the substrate.

[0070] After the pickled diamond seed crystals are placed in the first cavity of the base, a cover plate is installed on the base. The annular convex edge and the limiting recess on the cover plate are matched with the corresponding annular groove and the limiting convex recess on the base, and the installation can be smooth.

[0071] S3. Growing the substrate.

[0072] Place the installed substrate stage as a whole into the MPCVD equipment, introduce process gas after vacuuming, turn on the microwave, and set a high temperature and high pressure environment. Specifically, different types of process gases such as hydrogen, oxygen and / or methane are introduced into the MPCVD equipment to achieve different functions. When hydrogen is introduced, the MPCVD equipment cavity can be purified, air impurities can be removed, and the substrate surface can be cleaned at the same time. When oxygen is introduced, the substrate surface is etched, and hydrogen-oxygen plasma can fully etch the diamond phase diamond to remove defects on the surface and sub-surface of the diamond seed wafer, forming a surface that is conducive to the homoepitaxial growth of CVD single crystal diamond and improving the growth of single crystal diamond. Single crystal diamond homoepitaxial growth is performed when hydrogen and methane are introduced.

[0073] In one embodiment, before step S3, the method further comprises:

[0074] Place the substrate stage into the MPCVD equipment, set the microwave power of the MPCVD equipment to 30KW~40KW, and the cavity pressure to 10Kpa~15Kpa.

[0075] The high-voltage and high-power microwave feeding conditions in the MPCVD equipment can effectively activate carbon-containing groups, generate active groups in the plasma that are conducive to the high-quality and high-speed growth of single-crystal diamond, and can greatly optimize the uniformity of single-crystal diamond growth in a high-power microwave plasma environment. At higher power, the microwave plasma ball will completely cover the substrate stage and be stably distributed above the substrate stage as a whole. This also shows that the energy distribution of active groups is more uniform within a certain range, and single-crystal diamond sheets distributed in different areas on the substrate stage can obtain better layered growth steps. Therefore, this method can improve the growth rate and quality of single-crystal diamond.

[0076] S4. According to the growth stage of the substrate, replace the cover plate with a cover plate of different thicknesses so that the upper surface of the replaced cover plate is higher than the upper surface of the substrate.

[0077] Take out and observe the growth process of the substrate, replace the cover plate of different thickness according to the actual growth thickness, and clean the carbon layer on the edge. Keep the upper surface of the cover plate always higher than the upper surface of the substrate to maintain the semi-enclosed space state of the substrate in the substrate stage. Then put the cleaned substrate back into the substrate stage, repeat step S3, and let the substrate continue to grow.

[0078] S5. When the growth thickness of the substrate reaches a preset value, stop the growth of the substrate.

[0079] When the growth thickness of the substrate reaches a preset value, the introduction of methane is stopped.

[0080] As one implementation manner, after step S5, the method further includes:

[0081] The substrate stage is subjected to step-by-step cooling and heat preservation treatment.

[0082] The substrate is kept warm for a set time and then gradually cooled to complete the growth of the substrate.

[0083] In actual implementation, you can choose to use a substrate stage structure with a diameter of φ75mm, and select a diamond seed chip size of: 3*3*0.3mm. Select a closed substrate stage base with a diameter of φ75mm, a height of 5mm, and a surface roughness of the substrate stage base of Ra3.2um. On the substrate stage base, there are 37 first concave cavities evenly distributed in a ring, and their diameter is set to φ4.25mm and the depth is 150um. The diameter of the second concave cavity is φ3mm and the depth is 30um. The width of the annular groove on the substrate stage base is set to 2mm, and the height is set to 2mm. A limiting boss with a width of 2mm is retained at one end. Select the first cover plate corresponding to the substrate stage base. The cover plate has a diameter of φ75mm and a height of 3.65mm. The cover plate has 37 through holes evenly distributed in a ring corresponding to the first concave cavities of the substrate stage base, such as Figure 7 The figure shows the distribution design diagram of the cover plate through holes in this embodiment, wherein the diameter is set to φ6.25 mm, the bottom limiting groove has a diameter of φ71 mm and a depth of 2 mm, so the depth of the cover plate through holes is 1.65 mm.

[0084] In this embodiment, the growth process of 37 3*3 mm diamond seed wafers with a roughness of ≤30 nm and a thickness of about 300 um is taken as an example for specific description.

[0085] First, the diamond seed crystal is pickled, specifically:

[0086] (1) Arrange the diamond seed crystals in a quartz basket.

[0087] (2) Prepare an appropriate amount of diamond seed crystal pickling solution: V (concentrated sulfuric acid): V (concentrated nitric acid) = 3:1.

[0088] (3) Select a quartz cylinder of appropriate capacity, pour the acid-washing mixed solution prepared in step (2) into it, place the quartz cylinder on a heating table, set the heating temperature to 120° C., and boil with acid for about 60 minutes until no bubbles are generated on the surface of the diamond seed crystal.

[0089] (4) Rinse the diamond seed crystals that have been pickled in step (3) with deionized water in sequence.

[0090] (5) The diamond seed crystal rinsed in step (4) is subjected to general organic cleaning, and ultrasonic cleaning is performed with acetone and alcohol for 20 minutes in sequence.

[0091] (6) Blowing dry the diamond seed crystal cleaned in step (5) under a nitrogen atmosphere to complete the acid washing of the diamond seed crystal.

[0092] Secondly, the pickled diamond seed wafer is sequentially placed into the first concave cavity on the substrate stage base, the first cover plate is installed, and the whole is placed on the deposition table in the MPCVD equipment chamber for single crystal diamond pretreatment and growth, specifically:

[0093] (1) Turn on the MPCVD equipment, evacuate to a vacuum degree below 1.0X10-6mbar, introduce 2000sccm of hydrogen, turn on the microwave, set the temperature to about 700°C, and set the chamber pressure to about 13kPa for 60 minutes to purify the MPCVD equipment cavity, eliminate the influence of air impurities, and clean the surface of the diamond seed crystal.

[0094] (2) Under the conditions of step (1), 20 sccm of oxygen is introduced, the temperature is raised to 750°C, and the surface of the diamond seed crystal is etched under the conditions of V(H2):V(O2)=2000:20 sccm for 30 min. In this process, the hydrogen-oxygen plasma can fully etch the diamond phase diamond to remove defects on the surface and sub-surface of the diamond seed crystal, forming a surface that is conducive to the homoepitaxial growth of CVD single crystal diamond, thereby improving the growth quality of single crystal diamond.

[0095] (3) After etching in step (2) is completed, hydrogen and methane are introduced to carry out homoepitaxial growth of single crystal diamond. The operating power of the MPCVD equipment is set to 37KW, the temperature is increased to about 850°C, V(H2):V(CH4)=2000:100sccm, and the growth is carried out for 72h.

[0096] (4) After the growth of 72 hours in step (3) is completed, the single crystal diamond growth is observed and the growth thickness is measured according to the actual situation. For example, the diamond seed crystal grows from the initial thickness of 300um to 500um. The carbon layer on the edge is cleaned and the second cover plate is replaced. Its parameters are consistent with the first cover plate, but the height of the second cover plate is increased to 3.85mm, that is, the depth of the through hole of the second cover plate is increased to 1.85mm.

[0097] (5) The diamond sheet cleaned in step (4) is placed back into the substrate table, and steps (1) to (4) are repeated to continue the growth of single crystal diamond. For example, after another 72 hours of growth, the single crystal diamond growth is observed again. The diamond thickness increases from 500 um to 800 um. The edge carbon layer is cleaned again, and the third cover plate is replaced. Its parameters are consistent with the first cover plate and the second cover plate, but the height of the third cover plate is increased to 4.15 mm, that is, the depth of the through hole of the third cover plate is increased to 2.15 mm.

[0098] (6) After executing step (5), if the target thickness of 800um is reached, the methane is stopped, the temperature is raised to about 950°C, and kept warm for 2h in a hydrogen atmosphere, and then the temperature is gradually reduced by 200°C, and kept warm for 2h at each gradient until it reaches room temperature; at this time, the microwave is turned off, the hydrogen is stopped, and the equipment is turned off to obtain a single crystal diamond homoepitaxial wafer with a thickness of 800um.

[0099] The substrate growth method of the present application includes: after placing the substrate in the first cavity, covering the base with a cover plate, the upper surface of the cover plate being higher than the upper surface of the substrate; introducing process gas to grow the substrate; according to the growth stage of the substrate, replacing the cover plates of different thicknesses, so that the upper surface of the replaced cover plate is higher than the upper surface of the substrate; when the growth thickness of the substrate reaches a preset value, stopping the introduction of process gas. The substrate growth method of the present application adjusts the thickness of the cover plate according to the growth stage of the substrate, which can improve the growth state of the substrate and improve the growth quality of the substrate. Large-scale homogeneous epitaxial growth of single crystal diamond.

[0100] Third embodiment

[0101] The difference between this embodiment and the second embodiment is that the size of the diamond seed wafer is selected to be: 5*5*0.3mm. There are 19 first concave cavities evenly distributed in an annular shape on the substrate stage base, and the diameter thereof is set to φ7.08mm. There are 19 through holes evenly distributed in an annular shape on the corresponding cover plate, which correspond to the first concave cavities one by one, and the diameter thereof is set to φ9.48mm. Figure 8 Shown is a schematic diagram of the distribution design of the cover plate through holes in this embodiment.

[0102] For further explanation, the growth of 5*5*0.3 mm diamond seed crystals in this embodiment was tested, and diamond seed crystals of the same size were grown using the existing flat substrate table structure and method, and the results of growing single crystal diamonds were compared as shown in FIG. Fig. 9 shown.

[0103] like Fig. 9 (a) shows the diamond growth result obtained by using a flat open molybdenum table for diamond growth in the prior art. Fig. 9 (b) shows the diamond growth result obtained by using the method of the present application to grow diamond. According to the growth result, it can be intuitively compared that the single crystal diamond grown by the scheme described in the present patent has less polycrystalline edges, a flat surface, and no impurities.

[0104] The specific growth and detection process is as follows:

[0105] 1. In order to compare the effect difference between the present application and the prior art, the same batch of 5*5*0.3 mm diamond seed crystals were used for the same pretreatment.

[0106] 2. During the growth process, the temperature at the center and edge of the diamond seed crystal is monitored separately, and temperature measurement statistics are performed to evaluate the uniformity of the temperature field.

[0107] 3. The growth thickness at the center and edge of the diamond was statistically analyzed after 24h, 72h, 118h, 144h and 168h of growth to evaluate the growth efficiency and stability.

[0108] The test results of the growth process are summarized in Table 1:

[0109] (1) In the initial stage, the embodiment of the present application uses a first cover plate;

[0110] (2) After 24 hours of growth, the test results show that the temperature field uniformity of the method described in the embodiment of the present application is better than that of the prior art solution, but the growth thickness is basically the same, and the TTV of the diamond surface is basically the same, which means that in the initial stage of growth, the embodiment of the present application is basically the same as the prior art and has no obvious superiority;

[0111] (3) After 72 hours of growth, the temperature field uniformity of the embodiment of the present application is better than that of the existing solution and is more stable. Through the growth thickness detection, it can be seen that the diamond surface TTV of the embodiment of the present application is smaller, which means that after 72 hours of growth, the growth of the embodiment of the present application is more uniform;

[0112] (4) After 72 hours of growth, the embodiment of the present application was replaced with a second cover plate to continue growth. Tests were performed after 118 hours and 144 hours of growth, respectively. The test results show that in the middle stage of growth, the temperature field and growth uniformity of the growth process of the embodiment of the present application remain stable, while the disadvantages of the growth uniformity of the prior art solution gradually emerge, and the TTV of the diamond surface gradually increases;

[0113] (5) After 144 hours of growth, the third cover plate was used to continue growth in the embodiment of the present application, and the growth was terminated after 168 hours. Testing showed that the single crystal diamond grown in the embodiment of the present application had a high growth rate, stable surface growth uniformity, and an overall TTV of no more than 10 um, while the TTV of the prior art solution was close to 30 um.

[0114] In summary, the experimental results verify that the semi-enclosed substrate table structure of the embodiment of the present application always maintains the relative spatial position relationship between the growth interface and the external environment field during the diamond growth process, thereby allowing the diamond to grow uniformly and stably at a high speed.

[0115] Table 1 Statistics of the growth process of the present embodiment and the existing solution

[0116]

[0117] Fourth embodiment

[0118] The difference between this embodiment and the second embodiment is that the closed substrate stage base is selected with a diameter of φ100 mm and a height of 8 mm; 37 first concave cavities are evenly distributed in an annular manner on the substrate stage base, and 37 through holes corresponding to the first concave cavities are evenly distributed in an annular manner on the corresponding cover plate, such as Fig.10 Shown is a schematic diagram of the distribution design of the cover plate through holes in this embodiment.

[0119] The above embodiments are merely illustrative of the principles and effects of the present application and are not intended to limit the present application. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by a person of ordinary skill in the art without departing from the spirit and technical ideas disclosed in the present application shall still be covered by the claims of the present application.

Claims

1. A substrate stage for accommodating a substrate, characterized in that: comprising a base and at least one cover plate; The base is provided with at least one first concave cavity, and the side wall of the first concave cavity has a portion abutting against the substrate; the cover plate is provided with at least one through hole, and the cover plate can be replaceably matched with the base, and the thickness of different cover plates is different; when the cover plate is matched with the base, the projection of the first concave cavity is located inside the projection edge of the through hole, and the upper surface of the cover plate is higher than the upper surface of the substrate.

2. The substrate stage according to claim 1, characterized in that: The longitudinal section of the first cavity is rectangular, a second cavity is provided on the bottom surface of the first cavity, and an opening area of ​​the second cavity is smaller than an opening area of ​​the first cavity.

3. The substrate stage according to claim 2, characterized in that: The openings of the first cavity and the second cavity are both circular, the substrate is rectangular, the diameter of the first cavity matches the diagonal length of the substrate, and the diameter of the second cavity is less than or equal to the side length of the substrate.

4. The substrate stage according to claim 1, characterized in that: When the cover plate is matched with the base, the height difference between the upper surface of the cover plate and the upper surface of the substrate is 1.0 mm to 1.8 mm.

5. The substrate stage according to claim 1, characterized in that: The base is provided with a first limiting portion, and the cover is provided with a second limiting portion. When the cover is matched with the base, the first limiting portion matches the second limiting portion.

6. The substrate stage according to claim 5, characterized in that: The first limiting portion is an annular groove arranged along the upper edge of the base, and the second limiting portion is an annular convex edge arranged along the lower edge of the cover plate.

7. The substrate stage according to claim 6, characterized in that: At least one limiting boss is provided on the annular groove, and at least one limiting recess is provided on the annular convex edge. When the cover plate is matched with the base, the limiting boss matches with the limiting recess.

8. A method for growing a substrate, characterized in that: The following steps are involved: S1. Providing a substrate stage as described in any one of claims 1 to 7; Placing a substrate in a first concave cavity of a base of the substrate stage, wherein a side wall of the first concave cavity at least partially abuts against the substrate; S2. A cover plate is placed on top of the base, wherein the projection of the first cavity is located inside the projection edge of the through hole on the cover plate, and the upper surface of the cover plate is higher than the upper surface of the substrate; S3. growing the substrate; S4. According to the growth stage of the substrate, the cover plate of different thicknesses is replaced so that the upper surface of the replaced cover plate is higher than the upper surface of the substrate; S5. When the growth thickness of the substrate reaches a preset value, stop the growth of the substrate.

9. The method according to claim 8, characterized in that After the step S5, the method further includes: The substrate stage is subjected to a stepwise temperature reduction and heat preservation treatment.

10. The method according to claim 8, characterized in that The S3 step comprises: Place the substrate stage into the MPCVD device, set the microwave power of the MPCVD device to 30KW-40KW, and the cavity pressure to 10Kpa-15Kpa; A process gas is introduced to grow the substrate.

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