Substrate for diamond growth and diamond splicing growth method applying substrate

Abstract

The substrate for diamond growth comprises a splicing unit group, the splicing unit group comprises a first single crystal diamond and a second single crystal diamond, and in the splicing state, a first front face and a second front face are spliced to form a growth surface with a small splicing seam. The diamond splicing growth method comprises the following steps: S1, selecting the first single crystal diamond as a substrate to grow an epitaxial layer; s2, separating the epitaxial layer in the step S1 from the first substrate to obtain a second single crystal diamond; the method is characterized by further comprising the steps that S3, the first single crystal diamond and the second single crystal diamond are cut; s4, splicing the first front surface of the first single crystal diamond and the second front surface of the second single crystal diamond obtained in the step S3, and inversely arranging to obtain a spliced unit group; and S5, cutting and separating after growth to obtain the large-size monocrystal diamond. The method has the advantages that the quality of splicing seams of the obtained large-size diamonds is good, and the splicing method of the splicing unit group is simple.

Description

Technical Field

[0001] The invention relates to the field of joining single crystal or uniform polycrystalline materials with a certain structure, and in particular to a diamond splicing growth method. Background Art

[0002] Diamond has become one of the most promising materials in semiconductor materials due to its high thermal conductivity, high breakdown electric field, and high carrier mobility. However, compared with other semiconductor materials (such as Si, SiC, and GaN), the biggest obstacle to the application of diamond is the lack of high-quality single crystals at the inch level.

[0003] The main methods for preparing large-size single-crystal diamond wafers include heteroepitaxial growth, three-dimensional growth, and splicing growth, among which splicing growth is the most commonly used method among all the preparation methods. The splicing method is also called the Mosaic method, which is a method for preparing large-size single crystals by closely arranging multiple small-area conventional single-crystal diamond seed crystals and depositing and growing them on top to form a large-area single-crystal diamond. The splicing method has obvious advantages in preparing large-area single-crystal diamonds and can prepare inch-level single-crystal diamond wafers, but the splicing method also has disadvantages. The splicing joints are enriched with various forms of defects such as dislocations, polycrystalline, interfaces, and microcracks, which affect the mechanical strength, optical transmittance, and electrical properties, making it impossible to obtain high-quality large-size diamonds, which limits the advanced applications of large-size spliced ​​diamonds.

[0004] There are also some patents on the splicing growth of large-size single-crystal diamond in the prior art, such as the Chinese patent application with publication number CN110184653A, which proposes to splice two seed crystals after grooves are cut at the splicing seam, or the Chinese patent application with publication number CN117779205A, which proposes to splice the V-shaped groove at the splicing seam with preferential growth and repair. These splicing methods all achieve the splicing growth of two seed crystals by modifying the structure of the splicing groove at the splicing seam, but there are the following problems:

[0005] 1. The splicing grooves of the splicing substrate obtained by the above method have the notches facing upward at the splicing point, and the splicing seams are large, which will make it impossible for the single crystal diamond on the growth surfaces on both sides of the V-shaped grooves to grow continuously, and there are problems of inconsistent crystal orientation and tip effect. The crystal quality at the splicing seams of the grown epitaxial layer is still poor;

[0006] Second, this type of method uses a growth substrate with defects that the notch of the splicing groove is upward and the splicing seam is large, which leads to poor growth quality of the epitaxial layer at the splicing seam;

[0007] 3. In order to compensate for the problem of large joint seams, the above joint growth methods have additional repair steps in the joint grooves, or steps of etching special microgrooves to promote the continuous growth of single crystal diamond above the joint seams, but new problems have arisen: both the processing of special microgrooves and the repair of V-grooves require precise control of their process parameters, which makes the operation steps complicated and is not conducive to production;

[0008] 4. When the spliced ​​substrate is placed in the growth system for growth, polycrystalline will grow around the diamond, which will squeeze the growth space of the single crystal diamond inward, increase the stress and reduce the area of ​​the single crystal diamond;

[0009] Therefore, it is necessary to design new growth substrates and new methods to prepare large-sized, high-quality single-crystal diamonds. Summary of the invention

[0010] The first technical problem to be solved by the present invention is to provide a substrate for diamond growth with good crystal quality at the joint seams in view of the above-mentioned existing technical status.

[0011] The second technical problem to be solved by the present invention is to provide a diamond splicing growth method which uses the above substrate and can grow high-quality crystals at the splicing seams in response to the above-mentioned existing technical status.

[0012] The third technical problem to be solved by the present invention is to provide a diamond splicing growth method with simpler operation steps in view of the above-mentioned existing technical status.

[0013] The fourth technical problem to be solved by the present invention is to provide a method for avoiding the generation of polycrystalline diamond splicing growth in view of the above-mentioned existing technical status.

[0014] The technical solution adopted by the present invention to solve the first technical problem is: the substrate for diamond growth includes a splicing unit group, and the splicing unit group includes:

[0015] A first single crystal diamond, including a first bottom surface attached to the growth base and a first front surface directly used for diamond growth, as a first substrate;

[0016] A second single crystal diamond, including a second bottom surface in contact with the growth base and a second front surface directly used for diamond growth, serving as a second substrate;

[0017] Features:

[0018] The first front surface of the first single crystal diamond is cut to a first deviation angle of β degrees to be spliced, facing the first bottom surface; similarly,

[0019] The second front surface of the second single crystal diamond is cut to face the second bottom surface so that the second deviation angle to be assembled is γ degrees;

[0020] It also includes a connecting piece connecting the first single crystal diamond and the second single crystal diamond. In the assembled state, the first front side of the first single crystal diamond is assembled with the second front side of the second single crystal diamond to form a growth surface with a small joint, and a notch in an inverted V shape of α degrees is formed between the first bottom surface of the first single crystal diamond and the second bottom surface of the second single crystal diamond, and α=β+γ.

[0021] In order to ensure a stable connection between the first single crystal diamond and the second single crystal diamond, further, the first single crystal diamond and the second single crystal diamond are provided with an embedding opening for embedding the connecting piece in the area between the front and bottom surfaces of each. The user completes the splicing of the first substrate and the second substrate by embedding the connecting piece in the embedding opening, thereby preventing the problem of repeated startup and splicing alignment caused by the airflow blowing off the splicing piece when the splicing unit group is sent into the microwave plasma growth system for growth.

[0022] In order to reduce the temperature difference on both sides of the assembled unit group, the insertion opening is further parallel to the front or bottom surface of each single crystal diamond, and the connecting piece is a strip of diamond. The connecting piece plays an auxiliary heat transfer function for the diamond, so that the temperature distribution of the first single crystal diamond and the second single crystal diamond is uniform.

[0023] In order to make the growth surface of the spliced ​​unit group flush, further, the first deviation angle is β degrees, and 0°<β<1.5°, the second deviation angle is γ degrees, and 0°<γ<1.5°, the splicing seam width is 1-60μm, and the thickness difference between the first single crystal diamond and the second single crystal diamond is 0-40μm. The width of the splicing seam is much smaller than that of the prior art, which makes the quality of the large-sized diamond grown by the spliced ​​unit group at the splicing seam better than that of the existing spliced ​​growth substrate.

[0024] The technical solution adopted by the present invention to solve the second technical problem is: the diamond splicing growth method includes the following steps:

[0025] S1, selecting the first single crystal diamond as the first substrate, and depositing and growing an epitaxial layer on the first substrate by microwave plasma chemical vapor deposition;

[0026] S2, separating the epitaxial layer described in step S1 from the first substrate to form the second single crystal diamond, so that the thickness difference between the separated first single crystal diamond and the second single crystal diamond is within 40 μm, and the surface roughness Ra value of the first single crystal diamond and the second single crystal diamond to be grown is 0-50 nm;

[0027] It is characterized by also including:

[0028] S3, cutting the first single crystal diamond with the first front side facing the first bottom side to obtain a first deviation angle to be assembled, and cutting the second single crystal diamond with the second front side facing the second bottom side to obtain a second deviation angle to be assembled, wherein the first deviation angle is β degrees and the second deviation angle is γ degrees;

[0029] S4, the first front side of the first single crystal diamond and the second front side of the second single crystal diamond obtained in step S3 are spliced ​​and inverted to form the above-mentioned spliced ​​unit group, the spliced ​​unit group has the above-mentioned inverted V-shaped notch opening downward, the first front side of the first single crystal diamond and the second front side of the second single crystal diamond together form a growth surface, and the growth surface has the above-mentioned splicing seam; and the angle of the notch is α degrees, and α=β+γ;

[0030] S5, connecting the assembled unit group obtained in step S4 by the above-mentioned connecting piece, and placing it into a microwave plasma growth system with the growth surface facing upward, and then cutting and separating it to obtain large-sized single crystal diamond.

[0031] The technical solution adopted by the present invention to solve the third technical problem is: the specific operation steps of step S3 are:

[0032] S31, placing the second single crystal diamond obtained in step S2 in a direction that is the same as the step flow growth direction of the first single crystal diamond, that is, the second bottom surface of the second single crystal diamond is superimposed on the first front surface of the first single crystal diamond, and is superimposed on the first single crystal diamond with an overlapping area left;

[0033] S32, irradiating the overlapping area described in step S31 with laser light emitted by the laser source vertically downward to form a V-shaped incision with an angle of α, and β=γ, α=2β;

[0034] S33, removing the corner areas of the first single crystal diamond and the second single crystal diamond after being cut by laser, and obtaining the first single crystal diamond and the second single crystal diamond with deviation angles respectively. The step of vertically cutting the overlapping area by laser after translation adopted in the growth method ensures that the crystal orientation of the joint after cutting is consistent, and the setting of the overlapping area enables the operator to cut the first deviation angle and the second deviation angle of the two single crystal diamonds with only one knife, which simplifies the cutting process and operation.

[0035] In order to keep the diamond surface smooth, there is a cleaning operation between step S4 and step S5. Specifically, acetone and anhydrous ethanol are used to perform ultrasonic cleaning on the assembled unit group, and the ultrasonic cleaning time is 10 to 30 minutes; ultrapure water is then used to perform megasonic cleaning on the assembled unit group, and the cleaning time is 10 to 30 minutes, and nitrogen is used to blow away the residual water droplets on the surface, and the blowing time is 5 to 10 minutes. The cleaning operation removes inorganic ions, organic impurities, and cutting residues on the surface of the diamond. Megasonic cleaning is a cleaning method that uses ultra-high frequency ultrasonic energy at the megahertz level to remove submicron particles on the surface of the substrate. It will not produce a strong cavitation effect, thereby avoiding damage to the surface of the cleaning phenomenon and residual contaminants during the cleaning process. Blowing with nitrogen is to avoid secondary contamination of the residual cleaning liquid after cleaning.

[0036] The technical solution adopted by the present invention to solve the fourth technical problem is: in step S5, when placing the spliced ​​unit group into the microwave plasma growth system, an interference device needs to be placed on the growth base, and the interference device is a strip material with a melting point above 1500°C. The interference device can affect the interference position of the microwave on the growth base, thereby making the peak value of the plasma field around the spliced ​​unit group close to the interference device, and at the same time increasing the density of the plasma above the spliced ​​unit group. The interference device placed on the growth base makes the peak value of the plasma field around the spliced ​​unit group close to the interference device, avoiding the growth of polycrystalline around large-sized diamonds and squeezing the growth space of single-crystalline diamonds inward, reducing stress and increasing the area of ​​single-crystalline diamonds; at the same time, the density of plasma above the spliced ​​unit group is increased, thereby realizing the high-speed growth of large-sized diamonds on the growth surface of the spliced ​​unit group.

[0037] In order to further weaken the tip effect of the splicing piece boundary, preferably, the interference device includes at least two diamond bars, each of which is distributed around the splicing unit group, and the distance D from the boundary of the splicing unit group is 1.5-3 mm, and the height difference H from the splicing unit group 1 is 0.2-1 mm. The feature that the diamond bar is higher than the splicing unit group prevents the growing diamond from attracting too many plasma balls around, and the setting of the distance D between the diamond bar and the splicing unit group enables the large-sized diamond grown in the middle to be located at the optimal point for receiving the plasma ball.

[0038] In order to obtain diamonds of larger size, step S5 is followed by step S6, and the specific operations of step S6 include:

[0039] The spliced ​​unit group and the large-sized single crystal diamond obtained in step S5 are used as the first single crystal diamond and the second single crystal diamond, and the operations of steps S3, S4 and S5 are performed to obtain another large-sized single crystal diamond. The large-sized diamond grown by this method has good growth quality at the splicing seams and the spliced ​​unit group can be reused.

[0040] Compared with the prior art, the advantages of the present invention are:

[0041] 1. The splicing unit group uses the first front side and the second front side after laser cutting as the growth surface. The width of the splicing seam on the growth surface is only 1-60μm. The smaller the seam width, the closer the distance between the splicing pieces, and the less obvious the tip effect. The large-sized single crystal diamond grown on the growth surface has obvious step lines at the splicing seam, which is of high quality. There is no dislocation, cracks, or polycrystalline phenomenon at the splicing seam. At the same time, the smaller the splicing seam, the less the impact of lattice dislocation.

[0042] 2. On the growth surface of the spliced ​​unit group, since the crystal orientation of the diamond in the direction of a growth pattern is basically consistent, the groove when laser cutting the diamond is originally "V" shaped, so the epitaxial layer and the first substrate are stacked in the same posture as in step S1 and then the overlapping area is laser cut, which ensures that the crystal orientation of the large-sized single crystal diamond grown on the regrown substrate after splicing is not misaligned;

[0043] 3. Since the present invention does not use the notch as a processing object, but uses the first front surface and the second front surface as the growth surface, the notch and the first bottom surface and the second bottom surface can be used as the setting position of the connecting member. Furthermore, the setting of the connecting member makes the connection relationship between the first single crystal diamond and the second single crystal diamond stable, so that the relative position remains stable during growth in the microwave plasma growth system, and will not be blown off by the introduced growth gas and frequently stopped for correction;

[0044] 4. In the growth method, the first single crystal diamond is used as a substrate to grow the second single crystal diamond, and the first front side and the second front side are spliced ​​together to ensure that the crystal orientation at the splicing seam is consistent and there is no misalignment after splicing. The first deviation angle is cut by laser and the first deviation angle is spliced ​​together to ensure that when the first single crystal diamond and the second single crystal diamond are spliced ​​together, only the connection between the first front side and the second front side are in contact with each other, and the parts below the growth surface will not contact each other, thereby reducing the contact area between the first single crystal diamond and the second single crystal diamond as much as possible. The operation steps are simple and the increase of the splicing seam due to processing defects of the cutting surface is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a structural schematic diagram of a splicing unit group according to Embodiment 1 of the present invention;

[0046] Figure 2 It is a partial enlarged view of the longitudinal section of the splicing unit group at the notch of Example 1 of the present invention;

[0047] Figure 3 This is a schematic diagram of the structure of the embedding port of the splicing unit group according to Example 1 of the present invention;

[0048] Figure 4 Schematic diagram of the structure of the overlapping area in step S3 of Example 2 of the present invention (wherein the direction of the arrow is the translation direction of the second single crystal diamond);

[0049] Figure 5 is a schematic diagram of the structure after the overlapping area is cut in step S3 of embodiment 2 of the present invention;

[0050] Figure 6 A top view showing the positional relationship between the assembled unit group and the diamond strip in the microwave plasma growth system of Example 2 of the present invention;

[0051] Figure 7 It is a front view showing the positional relationship between the assembled unit group and the diamond strip in the microwave plasma growth system of Example 2 of the present invention;

[0052] Figure 8 This is a schematic diagram of the process of Embodiment 2 of the present invention;

[0053] Figures 9A to 9C This is a photo of the growth state of the large-sized single crystal diamond at the joint seam of Example 1 of the present invention, wherein: Fig. 9A This is a real picture of the assembled unit group. Fig. 9B This is a normal light optical photograph of a large diamond growing above the joint seam. Fig. 9C This is a filter optical photograph of a large diamond growing above a joint.

[0054] Figure 10A to Figure 10B This is a photo of the growth state of large-sized single crystal diamond at the joint seam of the joint unit group with a joint seam width of 24 μm in Example 2 of the present invention, wherein: Fig. 10A This is a photo of the joint seam of the assembled unit group (the yellow value is the width of the joint seam). Fig. 10B This is a filter optical photograph of a large diamond growing above a joint.

[0055] Figure 11A to Figure 11B This is a photo of the growth state of large-sized single crystal diamond at the joint seam of the joint unit group with a joint seam width of 57 μm in Example 2 of the present invention, wherein: Fig.11A This is a photo of the joint seam of the assembled unit group (the yellow value is the width of the joint seam). Fig. 11B This is a normal light optical photograph of a large-sized diamond growing above the joint seam;

[0056] Figure 12A to Figure 12B This is a photo of the growth state of large-sized single crystal diamond at the joint seam of a splicing unit group with a joint seam width of 60 μm in Example 2 of the present invention, wherein: Fig. 12A This is a photo of the joint seam of the assembled unit group (the yellow value is the width of the joint seam). Fig. 12B This is a normal light optical photograph of large-sized diamond growing above the joint seam. DETAILED DESCRIPTION

[0057] The present invention is further described in detail below with reference to the accompanying drawings.

[0058] Example 1

[0059] like Figures 1 to 3 As shown, it is a preferred embodiment of the present invention. The substrate for diamond growth in this embodiment is mainly used for the growth of diamonds. When the diamond to be grown is large in size, multiple growth substrates are often spliced ​​into a large growth substrate to grow larger diamonds. However, the quality of the existing large-sized diamonds grown by this method at the splicing seam is not ideal. It does not take into account the crystal orientation problem and the tip effect at the seed crystal splicing, and the interface position defect density is high, which leads to poor crystal quality at the splicing seam of the grown epitaxial layer. Therefore, it is beneficial to provide a substrate for diamond growth with good crystal quality at the splicing seam. The structure of the substrate for diamond growth will be described below:

[0060] See also Figure 1 and Figure 2The substrate for diamond growth includes a splicing unit group 1, which includes a first single crystal diamond 11 and a second single crystal diamond 12, wherein the first single crystal diamond 11 includes a first bottom surface 111 attached to a growth base 3 and a first front surface 112 directly used for diamond growth, and serves as a first substrate; the second single crystal diamond 12 includes a second bottom surface 121 attached to the growth base 3 and a second front surface 122 directly used for diamond growth, and serves as a second substrate; the first front surface 112 of the first single crystal diamond 11 is cut to the first bottom surface 111 into a first deviation angle of β degrees to be spliced ; Similarly, the second front side 122 of the second single crystal diamond 12 is cut to the second bottom side 121 to form a second deviation angle of γ degrees to be spliced; the splicing unit group 1 also includes a connector 13 connecting the first single crystal diamond 11 and the second single crystal diamond 12. In the spliced ​​state, the first front side 112 of the first single crystal diamond 11 is spliced ​​with the second front side 122 of the second single crystal diamond 12 to form a growth surface with a small splicing seam 14, and a notch 10 with a splicing inverted V shape of α degrees is formed between the first bottom side 111 of the first single crystal diamond 11 and the second bottom side 121 of the second single crystal diamond 12, and α=β+γ. The closer the distance that the diamond epitaxial layer needs to cover the splicing seam 14, the less time is required for covering. In the long-term growth process, the lattice may be dislocated, resulting in polycrystalline phenomenon. The smaller the splicing seam 14, the less the impact of lattice dislocation can be reduced.

[0061] See also Figure 3 The first single crystal diamond 11 and the second single crystal diamond 12 are provided with an embedding opening 15 for embedding the connecting piece 13 in the area between the front and bottom surfaces thereof. The user completes the splicing of the first substrate and the second substrate by embedding the connecting piece 13 in the embedding opening 15, thereby preventing the problem of repeated startup and splicing alignment caused by the airflow blowing off the splicing piece when the splicing unit group 1 is sent into the microwave plasma growth system for growth, so that the first single crystal diamond 11 and the second single crystal diamond 12 are firmly connected.

[0062] The insertion opening 15 is parallel to the front or bottom surface of each single crystal diamond, and the connecting member 13 is a strip of diamond. The connecting member 13 assists the heat transfer of the diamond, so that the temperature distribution of the first single crystal diamond 11 and the second single crystal diamond 12 is uniform, and the temperature difference on both sides of the spliced ​​unit group 1 is reduced.

[0063] See also Figure 2, the first deviation angle is β degrees, and 0.5°<β<1°, β is preferably 0.75°, the second deviation angle is γ degrees, and 0.5°<γ<1°, γ is preferably 0.75°; the width of the joint 14 is 1-60μm, and the thickness difference between the first single crystal diamond 11 and the second single crystal diamond 12 is 0-40μm. The width of the joint 14 is much smaller than that of the prior art, which makes the quality of the large-sized diamond grown by the joint unit group 1 better than that of the existing joint growth substrate at the joint, and also makes the growth surface 16 of the joint unit group 1 flush.

[0064] The advantage of the substrate for diamond growth in this embodiment is that the first front side 112 of the cut first single crystal diamond 11 and the second front side 122 of the second single crystal diamond 12 are spliced ​​to form a growth surface 16 with a small splicing seam, so that the crystal orientation at the splicing seam is the same, and the splicing seam 14 on the growth surface 16 is only 1 to 60 μm wide. For the growth condition at the splicing seam, please refer to Fig. 9B and Fig. 9C The large-sized single crystal diamond grown on the growth surface 16 has obvious step lines at the joints, and is of high quality. There is no dislocation, cracks, or polycrystalline phenomenon at the joints.

[0065] Example 2 A method for diamond splicing growth

[0066] This embodiment mainly describes the method for manufacturing the splicing unit set 1 of Embodiment 1 and the method for splicing and growing diamonds on the growth surface 16 of the splicing unit set 1 .

[0067] See also Figures 4 to 8 The diamond splicing growth method comprises the following steps:

[0068] S1, selecting the first single crystal diamond 11 of Example 1 as a first substrate, and depositing and growing an epitaxial layer on the first substrate by microwave plasma chemical vapor deposition;

[0069] S2, separating the epitaxial layer from the first substrate in step S1 to form the second single crystal diamond 12 of embodiment 1, so that the thickness difference between the separated first single crystal diamond 11 and the second single crystal diamond 12 is within 40 μm;

[0070] S3, the first front side 112 of the first single crystal diamond 11 is cut to the first bottom side 111 at a first deviation angle to be assembled, and the second front side 122 of the second single crystal diamond 12 is cut to the second bottom side 121 at a second deviation angle to be assembled, the first deviation angle is β degrees, and the second deviation angle is γ degrees;

[0071] S4, the first front side 112 of the first single crystal diamond 11 and the second front side 122 of the second single crystal diamond 12 obtained in step S3 are assembled and inverted to form an assembled unit group 1 of embodiment 1, the assembled unit group 1 has an inverted V-shaped notch 10 with an opening downward of embodiment 1, the first front side 112 of the first single crystal diamond 11 and the second front side 122 of the second single crystal diamond 12 together form a growth surface 16, and the growth surface 16 has a joint seam 14 of embodiment 1; and the angle of the notch 10 is α degrees, and α=β+γ;

[0072] S5, connecting the assembled unit group 1 obtained in step S4 by the connecting piece 13 of embodiment 1, and placing it in a microwave plasma growth system with the growth surface 16 facing upward, and then cutting and separating to obtain a large-sized single crystal diamond 2;

[0073] In addition, there is an operation of marking the side surface between step S1 and step S2. Specifically, the four-sided polycrystalline of the first single crystal diamond 11 on which the epitaxial layer is grown is cut off by laser cutting, and a V-shaped mark is made on one side of the diamond. The mark is also marked on the side surfaces of the first substrate and the epitaxial layer. The thickness of the epitaxial layer grown in step S1 is greater than 0.7 mm.

[0074] The three experimental results of the assembled unit group 1 and the large-sized single crystal diamond 2 obtained from steps S1 to S5 are shown in FIG. 9A to 9C , Fig. 10A and Fig. 10B , Fig.11A and Fig. 11B , Fig. 12A and Fig. 12B It can be observed from the experimental results that the large-sized diamond 2 grown has obvious step patterns, which means that the growth quality of the joint 14 is very good.

[0075] Please see Figure 4 and Figure 5 The specific operation steps of step S3 are:

[0076] S31, the second single crystal diamond 12 obtained in step S2 is placed in a translational manner in the same direction as the step flow growth direction of the first single crystal diamond 11, that is, the second bottom surface 121 of the second single crystal diamond 12 is overlapped with the first front surface 112 of the first single crystal diamond 11, and is overlapped on the first single crystal diamond 11 with an overlap region 3 left;

[0077] S32, irradiating the laser emitted by the laser source vertically downward toward the overlapping area 3 of step S31 to cut the cut to form a V-shape with an angle of α, and β=γ, α=2β;

[0078] S33, removing the edge and corner areas 17 of the first single crystal diamond 11 and the second single crystal diamond 12 after being laser cut, and obtaining the first single crystal diamond 11 and the second single crystal diamond 12 with deviation angles respectively; wherein the translation operation ensures that the crystal orientation of the joint after cutting is consistent, and the setting of the overlapping area 3 enables the operator to cut the two single crystal diamonds with the first deviation angle β and the second deviation angle γ with only one knife, thereby simplifying the cutting process and operation.

[0079] The operation of translation placement in step S3 is to place the processed second single crystal diamond 12 and the marked side of the first single crystal diamond 11 on the same side and then align the four corners of the two, and translate the second single crystal diamond 12 in a direction parallel to the marked side.

[0080] There is a cleaning operation between step S4 and step S5. Specifically, acetone and anhydrous ethanol are used to perform ultrasonic cleaning on the assembled unit group 1. The ultrasonic cleaning time is 10 to 30 minutes, preferably 20 minutes; ultrapure water is then used to perform megasonic cleaning on the assembled unit group. The cleaning time is 10 to 30 minutes, preferably 20 minutes, and nitrogen is used to blow away the residual water droplets on the surface. The blowing time is 5 to 10 minutes, preferably 8 minutes. The cleaning operation removes inorganic ions, organic impurities, and cutting residues on the diamond surface, keeping the diamond surface smooth.

[0081] Please see Figure 6 and Figure 7In step S5, when placing the assembled unit group 1 into the microwave plasma growth system, an interference device 4 needs to be placed on the growth base 3. The interference device 4 is a strip material with a melting point above 1500°C. The interference device 4 can affect the interference position of the microwave on the growth base 3, thereby making the peak value of the plasma field around the assembled unit group 1 approach the direction of the interference device 4, and at the same time increasing the density of the plasma above the assembled unit group 1. The interference device 4 placed on the growth base 3 makes the peak value of the plasma field around the spliced ​​unit group 1 approach the direction of the interference device 4, avoiding the growth of polycrystalline around the large-sized diamond 2 and squeezing the growth space of the single-crystalline diamond inward, reducing stress and increasing the area of ​​the single-crystalline diamond, while increasing the density of the plasma above the spliced ​​unit group 1, thereby realizing the high-speed growth of the large-sized diamond 2 on the growth surface 16 of the spliced ​​unit group 1; the interference device 4 of this embodiment includes at least two diamond bars, each of which is distributed around the spliced ​​unit group 1, and the distance D from the boundary of the spliced ​​unit group 1 is 1.5~3mm, D is preferably 2.25mm, and the height difference H with the spliced ​​unit group 1 is 0.2~1mm, H is preferably 0.6mm. The characteristic that the diamond bar is higher than the splicing unit group 1 prevents the growing diamond from attracting too many plasma balls around it. The setting of the distance D between the diamond bar and the splicing unit group 1 enables the large-sized diamond growing in the middle to be located at the optimal point for receiving the plasma ball, and further weakens the tip effect of the splicing piece boundary. The diamond bar can effectively "pull" the plasma ball more evenly onto the diamond growing in the middle, increase the density of the plasma above the diamond, and achieve high-speed growth; at the same time, this design can also effectively prevent the growth of the polycrystalline diamond film from being higher than the single-crystal diamond, avoid inward extrusion, and can grow synchronously with a long action time. In addition, the diamond bar here can also be replaced with the same number of molybdenum bars or other strip-shaped materials with a melting point of more than 1500°C.

[0082] Finally, step S5 is followed by step S6, and the specific operation of step S6 includes: using the spliced ​​unit group 1 and the large-sized single crystal diamond 2 obtained in step S5 as the first single crystal diamond 11 and the second single crystal diamond 12, and performing the operations of step S3, step S4, and step S5 to obtain another large-sized single crystal diamond 2. The large-sized diamond grown by this method has good growth quality at the splicing seams and the splicing unit group 1 can be reused to obtain a larger-sized diamond.

[0083] The large-sized diamond 2 grown by the diamond splicing growth method of this embodiment has obvious step patterns above the splicing seam 14 and consistent crystal orientation, avoiding the occurrence of crystal orientation dislocation around the large-sized diamond 2 and above the splicing seam 16, and the phenomenon of polycrystalline occupying the growth space of single crystal.

Claims

1. A substrate for diamond growth, comprising a spliced ​​unit group (1), wherein the spliced ​​unit group (1) comprises: A first single crystal diamond (11), comprising a first bottom surface (111) in contact with a growth base (3) and a first front surface (112) directly used for diamond growth, serving as a first substrate; A second single crystal diamond (12) includes a second bottom surface (121) that fits the growth base (3) and a second front surface (122) that is directly used for diamond growth, serving as a second substrate; Features: The first front surface (112) of the first single crystal diamond (11) is cut to a first deviation angle of β degrees toward the first bottom surface (111) to be spliced; similarly, The second front surface (122) of the second single crystal diamond (12) is cut toward the second bottom surface (121) to be assembled so that the second deviation angle is γ degrees; The invention also comprises a connecting member (13) for connecting the first single crystal diamond (11) and the second single crystal diamond (12); in a spliced ​​state, the first front surface (112) of the first single crystal diamond (11) and the second front surface (122) of the second single crystal diamond (12) are spliced ​​to form a growth surface with a small splicing seam (14); and a notch (10) in an inverted V shape with an angle of α is formed between the first bottom surface (111) of the first single crystal diamond (11) and the second bottom surface (121) of the second single crystal diamond (12), and α=β+γ.

2. The substrate for diamond growth according to claim 1, characterized in that: The first single crystal diamond (11) and the second single crystal diamond (12) are provided with an embedding opening (15) for embedding the connecting member (13) in the area between the front surface and the bottom surface of each.

3. The substrate for diamond growth according to claim 2, characterized in that: The embedding opening (15) is parallel to the front surface or the bottom surface of each single crystal diamond, and the connecting piece (13) is a diamond in the form of a strip.

4. The substrate for diamond growth according to any one of claims 1 to 3, characterized in that: The first deviation angle is β degrees, and 0°<β<1.5°, the second deviation angle is γ degrees, and 0°<γ<1.5°, the width of the joint seam (14) is 1 to 60 μm, and the thickness difference between the first single crystal diamond (11) and the second single crystal diamond (12) is 0 to 40 μm.

5. A method for growing diamond splicing, comprising the following steps: S1. Selecting the first single crystal diamond (11) as claimed in any one of claims 1 to 4 as a first substrate, and depositing and growing an epitaxial layer on the first substrate by microwave plasma chemical vapor deposition; S2, separating the epitaxial layer described in step S1 from the first substrate to form the second single crystal diamond (12) described in any one of claims 1 to 4, so that the thickness difference between the separated first single crystal diamond (11) and the second single crystal diamond (12) is within 40 μm, and the surface roughness Ra value of the growth surface of the first single crystal diamond (11) and the second single crystal diamond (12) is 0-50 nm; It is characterized in that Also included are: S3, cutting the first front surface (112) of the first single crystal diamond (11) toward the first bottom surface (111) at a first deviation angle to be assembled, and cutting the second front surface (122) of the second single crystal diamond (12) toward the second bottom surface (121) at a second deviation angle to be assembled, wherein the first deviation angle is β degrees and the second deviation angle is γ degrees; S4, the first front side (112) of the first single crystal diamond (11) and the second front side (122) of the second single crystal diamond (12) obtained in step S3 are spliced ​​and inverted to form a spliced ​​unit group (1) as claimed in any one of claims 1 to 4, wherein the spliced ​​unit group (1) has a downwardly opening inverted V-shaped notch (10) as claimed in any one of claims 1 to 4, and the first front side (112) of the first single crystal diamond (11) and the second front side (122) of the second single crystal diamond (12) together form a growth surface (16), and the growth surface (16) has a splicing seam (14) as claimed in any one of claims 1 to 4; and the angle of the notch (10) is α degrees, and α=β+γ; S5. Connect the assembled unit group (1) obtained in step S4 by the connecting piece (13) as described in any one of claims 1 to 4, and place it in a microwave plasma growth system with the growth surface (16) facing upward, and then cut and separate it to obtain a large-sized single crystal diamond (2).

6. The method for diamond splicing growth according to claim 5, characterized in that: The specific operation steps of step S3 are: S31, placing the second single crystal diamond (12) obtained in step S2 in a direction that is the same as the step flow growth direction of the first single crystal diamond (11), that is, the second bottom surface (121) of the second single crystal diamond (12) is superimposed on the first front surface (112) of the first single crystal diamond (11), and is superimposed on the first single crystal diamond (11) with an overlapping area (3) left; S32, irradiating the overlapping area (3) described in step S31 vertically downward with laser light emitted by the laser source to cut the cut so as to form a V-shape with an angle of α, and β=γ, α=2β; S33, removing the edge and corner regions (17) of the first single crystal diamond (11) and the second single crystal diamond (12) after being cut by laser, and obtaining the first single crystal diamond (11) and the second single crystal diamond (12) having deviation angles, respectively.

7. The method for diamond splicing growth according to claim 5, characterized in that: There is a cleaning operation between step S4 and step S5. Specifically, acetone and anhydrous ethanol are used to perform ultrasonic cleaning on the assembled unit group (1), and the ultrasonic cleaning time is 10 to 30 minutes. Ultrapure water is then used to perform megasonic cleaning on the assembled unit group, and the cleaning time is 10 to 30 minutes. The residual water droplets on the surface are blown away by nitrogen gas, and the blowing time is 5 to 10 minutes.

8. The method for diamond splicing growth according to claim 5, characterized in that: In the step S5, when placing the assembled unit group (1) into the microwave plasma growth system, an interference device (4) needs to be placed on the growth base (3). The interference device (4) is a strip-shaped material with a melting point above 1500° C. The interference device (4) can affect the interference position of the microwave on the growth base (3), thereby making the peak value of the plasma field around the assembled unit group (1) approach the direction of the interference device (4), while increasing the density of the plasma above the assembled unit group (1).

9. The method for diamond splicing growth according to claim 6, characterized in that: The interference device (4) comprises at least two diamond bars, each of which is distributed around the splicing unit group (1), with a distance D from the boundary of the splicing unit group (1) of 1.5 to 3 mm and a height difference H from the splicing unit group (1) of 0.2 to 1 mm.

10. The method for diamond splicing growth according to claim 6, characterized in that: Step S5 is followed by step S6, and the specific operations of step S6 include: The assembled unit group (1) and the large-sized single crystal diamond (2) obtained in step S5 are used as the first single crystal diamond (11) and the second single crystal diamond (12), and the operations of steps S3, S4 and S5 are performed to obtain another large-sized single crystal diamond (2).

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