JP2007331955A - Method for producing diamond - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which the shape (morphology) of the growth surface of a diamond can be easily controlled when a diamond single crystal is grown on a diamond substrate by a microwave plasma CVD process. <P>SOLUTION: The method for producing a diamond comprises conducting the growth of the diamond by controlling the shape of the growth surface of the diamond by adjusting the thickness of a member 7b that includes the top plate 7d of the substrate surrounding member 7b, wherein the substrate holder 7 is a substrate holder 7 that is composed of an electrically conducting material and is provided with the substrate surrounding member 7b around the periphery of a substrate mounting part 7a and that has a structure wherein the substrate holder 7 including the substrate surrounding member 7b is integrated or has a structure wherein a given thickness part can be separated from the top plate 7d of the substrate surrounding member 7b, as well as the substrate holder 7 for producing a diamond is a substrate holder 7 that is composed of an electrically conducting material and is provided with the substrate surrounding member 7b around the periphery of a substrate mounting part 7a and that has a structure wherein the substrate holder 7 including the substrate surrounding member 7b is integrated or has a structure wherein a given thickness part can be separated from the top plate 7d. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a diamond manufacturing method by a microwave plasma CVD method and a substrate support for diamond manufacturing.

  Diamond having excellent characteristics as a semiconductor is expected as a material for semiconductor devices such as high-frequency / high-power devices and ultraviolet light-emitting devices.

  Currently, diamond single crystals are grown mainly by high-pressure synthesis, vapor phase synthesis, or the like. As a promising method among vapor phase synthesis methods, a microwave plasma CVD method is known in which diamond crystals are grown using plasma formed by microwave discharge by flowing hydrogen and methane gas in a reduced-pressure atmosphere. Yes.

  In these diamond crystal growth methods, research to reduce the working time and growth cost has been extensively made to date, but there are examples of research to improve the growth speed, but when growing diamonds, No specific method has been proposed for controlling the shape of the growth surface.

  For example, in diamond homoepitaxial growth by the microwave plasma CVD method, it is possible to grow a diamond single crystal at a rate exceeding 100 μm per hour by adding a small amount of nitrogen to a reaction gas composed of hydrogen gas and methane gas. It has been reported (see Non-Patent Document 1 below). In addition, in the diamond growth method using the microwave plasma CVD method, a method of growing diamond at a high speed by using a substrate support having a shape in which the mounting portion of the diamond substrate is raised with respect to the outer peripheral edge portion is also disclosed. (See Patent Document 1 below).

  Further, as a diamond synthesizer for realizing a high growth rate, a synthesizer using a combination of known diamond manufacturing techniques is disclosed (see Patent Document 2 below). This synthesizer is a known technique, in which a diamond substrate is placed on a substrate support made of a conductor such as molybdenum (see Non-Patent Documents 2 to 4 below), and heat is released to the substrate support. (See Non-Patent Documents 3 and 4 below), Measuring the temperature of diamond using a non-contact type temperature measuring device (see Non-Patent Document 3 below), and growing to a predetermined thickness (Patent Patents below) A high growth rate is to be realized by combining means such as Reference 3). However, Patent Document 2 does not disclose any method for controlling the shape of the growth surface, and does not consider any means for controlling the shape of the growth surface. For this reason, in a synthesis apparatus using a combination of the above-described known techniques, it is possible to increase the diamond growth rate, but it is not possible to control the shape of the diamond growth surface.

  Moreover, in the method of Patent Document 2, the growth of the growth surface is hopeless because the diamond growth is performed with the periphery of the diamond substrate in contact with the substrate support. Furthermore, it is difficult to slide the substrate and the substrate support in different directions after growth, and the substrate may be damaged when separating them.

As described above, in the conventionally known diamond manufacturing method using the microwave plasma CVD method, diamond growth is performed without controlling the shape of the growth surface. For this reason, it is necessary to polish the grown diamond into a target shape, which contributes to an increase in working time and cost.
A. Chayahara, Y. Mokuno, Y. Takasu, H. Yoshikawa, N. Fujimori, Diamond Relat. Mater. 13 (2004), 1954-1958 M. Kamo, Y. Sato, S. Matsumoto, N. Setaka, J. Crystal Growth 62 (1983), 642-644 T. Tachibana, Y. Ando, A. Watanabe, Y. Nishibayashi, K. Kobashi, T. Hirao, K. Oura, Diamond Relat. Mater. 10 (2001), 1569-1572 The Institute of Electrical Engineers of Japan, Microwave Plasma Research Committee, “Microwave Plasma Technology”, published by Ohm, pages 151-152 JP-A-2005-255507 JP 2005-508279 A Japanese Patent Laid-Open No. 9-20589

  The present invention has been made in view of the current state of the prior art described above, and its main purpose is to simplify the shape (morphology) of a diamond growth surface when growing a diamond single crystal by a microwave plasma CVD method. Is to provide a method that can be controlled.

  The present inventor has intensively studied to achieve the above-described object. As a result, in a method of growing a diamond crystal on a diamond substrate by a microwave plasma CVD method, a predetermined thickness portion is separated from an integrated structure having a substrate surrounding portion around the substrate mounting surface or a top surface as a substrate support. It has been found that the shape of the diamond growth surface can be controlled by using a substrate support having a possible structure and adjusting the thickness of the member including the top surface of the substrate surrounding portion.

  By using this method, it becomes possible to arbitrarily adjust the shape of the growth surface according to the purpose. For example, when controlling the shape of the growth surface to be convex or flat, the growth of diamond Can be produced continuously for a long time, and large diamond production can be realized, and when the growth surface has a concave shape, the growth surface is perpendicular to the growth direction of the main growth surface. It has been found that various growth surfaces according to the purpose can be formed very easily, such as being able to be enlarged.

  The present invention has been completed based on these findings.

That is, this invention provides the following diamond manufacturing method and the substrate support body for diamond preparation which can be used by this method.
1. In a method of growing a diamond crystal on a diamond substrate by a microwave plasma CVD method,
The substrate support installed in the CVD apparatus is a support made of a conductive material having a substrate surrounding portion around the substrate mounting surface, and the substrate support including the substrate surrounding portion is integral or It is a structure in which a predetermined thickness portion can be separated from the top surface of the substrate surrounding portion,
A diamond manufacturing method characterized in that diamond growth is performed by controlling a shape of a diamond growth surface by adjusting a thickness of a member including a top surface of the substrate surrounding portion.
2. Item 2. The method according to Item 1, wherein the growth of the end surface of the diamond substrate is suppressed by increasing the thickness of the member including the top surface of the substrate surrounding portion.
3. Item 2. The method according to Item 1, wherein the growth of the end surface of the diamond substrate is promoted by reducing the thickness of the member including the top surface of the substrate surrounding portion.
4). The top surface of the substrate surrounding portion of the substrate support is substantially flush with the surface of the diamond substrate, and the thickness of the member including the top surface of the substrate surrounding portion is made larger than the thickness of the diamond substrate, thereby growing the diamond. Item 2. The method according to Item 1, wherein the surface has a convex shape.
5). The top surface of the substrate surrounding portion in the substrate support is substantially flush with the surface of the diamond substrate, and the thickness of the member including the top surface of the substrate surrounding portion in the substrate support is substantially the same as the thickness of the diamond substrate. 2. The method according to item 1, wherein the diamond growth surface has a flat shape.
6). The top surface of the substrate surrounding portion in the substrate support is substantially flush with the surface of the diamond substrate, and the thickness of the member including the top surface of the substrate surrounding portion in the substrate support is made smaller than the thickness of the diamond substrate. 3. The method according to item 1, wherein the diamond growth surface has a concave shape.
7). Item 7. The method according to any one of Items 4 to 6, wherein the difference in height between the top surface of the substrate surrounding portion and the surface of the diamond substrate in the substrate support is less than 0.3 mm.
8). A substrate support made of a conductive material having a substrate surrounding portion around a substrate placement surface used in the method of any one of Items 1 to 7, wherein the substrate support including the substrate surrounding portion is integrated. A substrate support for producing diamond by a microwave plasma CVD method having a structure in which a predetermined thickness portion is separable from the top surface.

  In the present invention, as a method for producing diamond, a method of growing a diamond crystal on a diamond substrate by a microwave plasma CVD method is employed.

  FIG. 1 shows a schematic diagram of an example of a microwave plasma CVD apparatus. In the apparatus shown in FIG. 1, a microwave plasma CVD apparatus 1 includes a microwave power source 2, a waveguide 3 for propagating microwaves, a microwave introduction dielectric window 4, a cavity resonator type reaction vessel 5, and cooling inside. A stage 6 through which water W passes and a substrate support 7 installed on the stage 6 are provided.

  The reaction vessel 5 is provided with a source gas introduction port 5a for introducing a source gas and an exhaust port 5b for evacuating the inside of the vessel.

  The microwave generated by the microwave power source 2 is introduced into the reaction vessel 5 as indicated by an arrow in FIG.

  There are no particular limitations on the specific production conditions, and diamond may be grown according to known conditions. As the raw material gas, for example, a mixed gas of methane gas and hydrogen gas can be used, and further, the growth rate can be improved by adding nitrogen gas thereto.

  As an example of specific diamond growth conditions, in a mixed gas of hydrogen, methane, and nitrogen used as a reaction gas, methane has a ratio of about 0.01 to 0.33 mol with respect to 1 mol of hydrogen supply. The nitrogen is preferably supplied at a ratio of about 0.0005 to 0.1 mol per 1 mol of methane supplied. Moreover, what is necessary is just to usually set the pressure in a plasma CVD apparatus to about 13.3-40 kPa. As the microwave, a microwave having a frequency permitted for industrial and scientific use such as 2.45 GHz and 915 MHz is usually used. The microwave power is not particularly limited, but is usually about 0.5 to 5 kW. Within such a range, for example, each condition may be set so that the temperature of the substrate (diamond seed crystal) is about 1000 to 1300 ° C.

  In the method of the present invention, a substrate support made of a conductive material having a substrate surrounding portion around the substrate mounting surface is used as a substrate support for mounting the diamond substrate. The support is usually formed of a metal such as Mo or W, or a conductor such as an alloy. As long as this condition is satisfied, the shape of the substrate support is arbitrary.

  In the present invention, the substrate placement portion of the substrate support is formed by a recess, and the substrate surrounding portion refers to a peripheral portion surrounding the diamond substrate placed on the substrate placement surface of the substrate support. .

  FIG. 2 is a schematic view showing an example of a substrate support used in the present invention. The substrate support shown in FIG. 2 has a cylindrical shape as a whole, the substrate mounting surface 7a has the same or similar planar shape as the diamond substrate 8, and has a substrate surrounding portion 7b around it. .

FIG. 2A shows a support having a structure in which the substrate support 7 including the substrate surrounding portion 7b is integrated. FIGS. 2B and 2C show a support having a structure in which a member forming the substrate surrounding portion 7b and a member 7c including the substrate mounting surface 7a are separated. Specifically, in the support shown in FIG. 2B, the member 7b forming the substrate surrounding portion is a disk-shaped member having a hollow portion that is the same as or similar to the shape of the diamond substrate in the central portion. The member 7b forming the substrate surrounding portion is installed on a columnar member 7c having the same diameter as the member. In the support shown in FIG. 2 (c), the member 7b forming the substrate surrounding portion is a disk-shaped member having a hollow portion at the center portion that is the same as or similar to the shape of the diamond substrate, and is thicker than the diamond substrate. Is a small member. The member 7c including the substrate placement surface 7a is a columnar member, and a concave portion serving as a part of the substrate placement portion is formed on one bottom surface thereof. The planar shape of the concave portion in this member is the same shape as the hollow portion of the member 7b forming the substrate surrounding portion. The member 7b forming the substrate surrounding portion is placed on the member 7c including the substrate placement surface 7a, and the substrate is placed by the hollow portion of the member 7b and the concave portion of the member 7c including the substrate placement surface. A space is formed.

In the method of the present invention, by setting the thickness t ₂ of the member including a top surface 7d of the substrate surrounding portion to size, it is possible to control the shape of the growth surface of the diamond substrate. Specifically, increasing the thickness t ₂ of the member 7b including top 7d of the substrate surrounding portion, it is possible to suppress the growth of the end portion 8a of the diamond substrate 8, the thickness of the member 7b including top 7d the smaller the t ₂ is, it is possible to promote the growth of the end portion 8a of the diamond substrate 8.

  The embodiment of the method of the present invention will be described below with reference to FIG. FIG. 2 shows a case where the top surface 7d of the substrate surrounding portion of the substrate support is substantially flush with the surface of the diamond substrate 8 placed on the substrate placement surface.

Support shown in FIG. 2 (a), the entire substrate support 7 comprising a substrate surrounding portion 7b is a structure in which an integrated, the thickness t ₂ of the member including a top surface 7d of the substrate surrounding portion, the diamond substrate It is larger than the thickness t ₁ of. In this state, when a diamond crystal is grown on the diamond substrate 8 by the microwave plasma CVD method under the above-described conditions, the growth of the end portion 8a is suppressed as compared with the central portion 8b of the diamond substrate. The shape of the growth surface is a convex shape with the central portion 8b raised. In this case, the thickness t ₂ of the member including a top surface 7d is be greater than the thickness t ₁ of the diamond substrate, usually, the thickness t ₂ of the member including a top surface 7d is a diamond substrate thickness t ₁ is preferably greater than about 0.3 mm. The maximum thickness of the member including a top surface, but are not limited to, usually, it may be the thickness of up to 5 times the thickness t ₁ of the diamond substrate.

The support shown in FIG. 2B is a support having a structure in which a disk-shaped member 7b having a hollow portion and a columnar member 7c including a substrate mounting surface 7a are separated. The planar shape of the hollow portion of the disc-shaped member 7b is a plan shape identical or similar to diamond substrate, the thickness of the disc-shaped member 7b is substantially identical to the thickness t ₁ of the diamond substrate. In this case, the thickness t ₂ of the member 7b including top 7d of the substrate support, since the thickness of the disc-shaped member 7b, the thickness t ₂ of the member 7b including top 7d of the substrate surrounding portion, diamond It is almost the same as the thickness t _{1 of the} substrate. In this state, when a diamond crystal is grown on the diamond substrate 8 by the microwave plasma CVD method under the above-described conditions, the growth of the central portion 8b and the end portion 8a of the diamond substrate is substantially the same, and the diamond growth surface. Becomes a flat shape. In this case, for example, the thickness t ₂ of the member 7b including top 7d of the substrate surrounding portion, similarly to the case difference between the thickness t ₁ of the diamond substrate is less than about 0.3 mm, similarly to the case of the In addition, the diamond growth surface can be made flat.

In the support shown in FIG. 2 (c), the member 7 b forming the substrate surrounding portion is a disk-shaped member having a hollow portion that is the same as or similar to the shape of the diamond substrate at the center portion. It is a member with a small thickness. FIG. 3 shows a partially enlarged view of the periphery of the substrate placement surface 7a in FIG. The member 7c including the substrate placement surface 7a is a columnar member, and a concave portion serving as a part of the substrate placement portion is formed on one bottom surface thereof. In this case, the thickness t ₂ of the member 7b including top 7d of the substrate surrounding portion becomes a thickness of the disc-shaped member is smaller than the thickness t ₁ of the diamond substrate. In this state, when a diamond crystal is grown on the diamond substrate 8 by the microwave plasma CVD method under the above-described conditions, the growth of the end portion 8a is promoted compared to the central portion 8b of the diamond substrate. The shape of the growth surface is a concave shape in which the growth of the central portion 8b is small and the end portion 8a is greatly grown. In this case, the thickness t ₂ of the member including the top surface 7d, may be smaller than the thickness t ₁ of the diamond substrate, usually, the thickness t ₂ of the member including the top surface 7d, the thickness of the diamond substrate than t _1, it is preferred not less than about 0.3mm smaller.

  In the diamond growth surface control method shown in FIGS. 2A to 2C, the top surface 7d of the substrate surrounding portion of the substrate support and the diamond substrate 8 placed on the substrate placement surface The surface position (height) is preferably matched within an error range of about 0.3 mm.

For reasons that can control the shape of the growth surface by method described above, and although not necessarily clear, the thickness t ₂ of the member 7b is larger than the thickness t ₁ of the diamond substrate comprising a top surface 7d of the substrate surrounding portion, the plasma When performing the CVD process, the cooling effect by the substrate support on the end portion 8a of the diamond substrate is increased, the growth of the end portion 8a is suppressed, and the shape of the growth surface becomes a convex shape with the central portion 8b raised, , when the thickness t ₂ of the member 7b including top 7d of the substrate surrounding portion is smaller than the thickness t ₁ of the diamond substrate is smaller cooling effect of the substrate support relative to the end 8a of the diamond substrate, in particular, Since the member 7b including the top surface 7d and the member 7c including the substrate mounting surface are separated from each other, the separation surface generates a heat insulating effect, and the cooling of the end 8a of the diamond substrate is reduced. It is considered that the rejection effect is further reduced, and as a result, the growth of the end 8a is promoted, and the shape of the growth surface becomes a concave shape in which the end 8a is raised.

  In the method of the present invention, the shape of the substrate support to be used is not limited to the shape of the support shown in FIG. 2, and the substrate support having the substrate surrounding portion 7b around the substrate mounting surface 7a, that is, the substrate As long as the mounting portion is a substrate support formed by a concave portion, a support having an arbitrary shape can be used. For example, in FIG. 2, a columnar substrate support is used, but a truncated cone-shaped substrate support having a larger bottom surface area than the upper surface of the substrate support may be used. Furthermore, it is also possible to use a substrate support having a structure in which the member including the substrate mounting portion and the outer peripheral edge member used in Examples 1 and 2 described later are separated. In the case of using any shape of support, the shape of the diamond growth surface can be controlled by adjusting the thickness of the member including the top surface of the substrate surrounding portion as in the case shown in FIG. .

Also, the shape of the substrate placement surface 7a is not limited to the same shape or similar shape as the diamond substrate to be used, and any substrate having a placement surface of any shape can be used as long as the diamond substrate can be placed thereon. Can be used. The distance between the end surface of the diamond substrate and the substrate surrounding portion, that is, the distance between the diamond substrate end surface 8a and the inner wall surface 7e of the substrate mounting portion is not particularly limited, but the cooling effect by the substrate surrounding portion is sufficient. Therefore, it is preferably about 0.5 mm or less, more preferably about 0.1 mm or less.

FIG. 2 shows an example in which the diamond substrate is placed so that the surface of the diamond substrate is substantially flush with the top surface 7d of the substrate surrounding portion. However, the present invention is not limited to this, and the position of the diamond substrate surface is the position of the substrate surrounding portion. It may be set higher than the position of the top surface 7d, or may be set lower than the position of the top surface 7d. In this case, the growth of the end surface 8a of the diamond substrate tends to be promoted as the position of the diamond substrate surface increases. Therefore, in order to control the shape of the growth surface of the diamond substrate, according to the surface position of the diamond substrate, it is necessary to determine the thickness t ₂ of the member including a top surface 7d. For example, when the position of the diamond substrate surface is higher than the position of the top surface 7d of the substrate surrounding portion, the surface of the diamond substrate is flush with the top surface 7d of the substrate surrounding portion in order to make the growth surface convex. as compared with the case of, it is necessary to increase the thickness t ₂ of the member 7b including top 7d. Similarly, when the position of the surface of the diamond substrate is lower than the position of the top surface 7d of the substrate surrounding portion, the surface of the diamond substrate is flush with the top surface 7d of the substrate surrounding portion in order to make the shape of the growth surface concave. as compared with the case of, it is necessary to reduce the thickness t ₂ of the member 7b including top 7d.

  According to the method of the present invention, the shape (morphology) of the growth surface, which was difficult with the conventional microwave plasma CVD method, can be controlled by a simple method. For this reason, by adopting the method of the present invention, it becomes easy to produce diamond having a shape corresponding to the purpose of use.

  For example, when the conditions are set so that the diamond growth surface is convex or flat, diamond growth can be performed continuously, and large diamond can be manufactured easily. Further, when the conditions are set so that the diamond growth surface is concave, the growth surface can be enlarged in the direction perpendicular to the main growth direction.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
A substrate support 7 was installed at substantially the center of the cooling stage 6 using a microwave plasma CVD apparatus having a cavity resonator type reaction vessel shown in FIG.

  The substrate support 7 is composed of a substrate mounting member and an outer peripheral edge member 7f, and is a molybdenum support having a truncated cone shape as a whole. The member for the substrate placement portion is a columnar shape having a diameter of about 12 mm and a height of about 8.5 mm, in which a member including the substrate surrounding portion 7b and a member including the substrate placement surface 7a are integrated. A 3 mm × 3 mm square recess having a depth of 0.5 mm is formed at the center of the bottom surface. The outer peripheral edge member 7f has a truncated cone shape with a bottom diameter of 20 mm and 12 mm, and a height of about 8.5 mm, and has a concentric cavity with a diameter of 12 mm. The substrate mounting portion member is disposed inside.

  In the substrate support, the 3 mm × 3 mm bottom surface of the concave portion of the substrate mounting portion member is the substrate mounting surface 7a, and the peripheral portion thereof is the substrate surrounding portion 7b.

As the diamond substrate (seed crystal), a plate crystal of 3 × 3 × 0.5 mm ³ obtained by cutting and polishing a single crystal diamond obtained by a high-pressure synthesis method in parallel to the {100} plane was used. .

FIG. 4A is a central longitudinal sectional front view showing a state in which the diamond substrate (seed crystal) 8 is placed on the placement surface of the substrate support. The diamond substrate 8 is placed on the placement portion (concave portion) without a gap. In this state, the top surface 7d of the substrate surrounding portion of the substrate support is flush with the surface of the diamond substrate, and the member including the top surface 7d of the substrate surrounding portion, that is, the thickness t _{2 of the} entire substrate support. Is 5 times or more the thickness t ₁ of the diamond substrate.

First, after evacuating the reaction vessel, H ₂ gas was introduced, the pressure inside the reaction vessel was set to 10 Torr (1333 Pa), and the plasma was ignited by applying microwave (2.45 GHz) power of 500 W . Then, gradually increase the pressure, H ₂ gas flow rate, N ₂ gas flow rate, and microwave power, respectively, the pressure is 180 Torr (24.0 KPa), the H ₂ gas flow rate is 500 cc (standard state) / min, N ₂ The gas flow rate was set to 1.8 cc (standard condition) / min. Next, after setting the microwave power between 1000-3000 W so that the substrate temperature becomes 1130 ° C., the N ₂ gas flow rate is changed to 0.6 cc (standard state) / min, and CH ₄ gas 60 cc (standard) State) / min was introduced to perform steady diamond growth.

After 4 hours of growth, stop crystal growth by stopping CH ₄ and N ₂ gases, gradually reduce pressure, H ₂ gas flow rate, and microwave power to reduce microwave power to 0, and reaction vessel Was opened to the atmosphere, and the grown crystal was taken out.

  As a result of measuring the thickness of the obtained diamond single crystal with a micrometer, the thickness increased by about 0.2 mm in the main growth direction.

FIG. 5A is a schematic cross-sectional view showing the result of observing the obtained diamond crystal with an optical microscope. As is apparent from this drawing, the shape of the diamond 9 grown on the surface of the diamond substrate 8 was convex.

Example 2
As the microwave plasma CVD apparatus 1, the same one as in Example 1 was used.
As the substrate support, there is a placement portion member in which a disc-like member 7b having a hollow portion is disposed on a columnar member 7c including a substrate placement surface 7a, and an outer peripheral edge member 7f. As a whole, a truncated cone-shaped support made of molybdenum was used.

  As the mounting member, a disk-shaped member 7b having a diameter of about 12 mm and a thickness of about 0.5 mm having a hollow portion of 3 mm × 3 mm at the center is a cylindrical member 7c having a diameter of about 12 mm and a height of about 8 mm. The member of the separation structure arranged on the top was used. As the outer peripheral edge member 7f, the same member as in Example 1 was used, and the mounting member having the above-described separation structure was inserted into a concentric cavity having a diameter of 12 mm.

As a diamond substrate (seed crystal), 3 × 3 × 0.5 mm ³ obtained by cutting and polishing a single crystal diamond obtained by a high-pressure synthesis method in parallel to the {100} plane in the same manner as in Example 1. Plate-like crystals were used.

FIG. 4B is a central longitudinal sectional front view showing a state in which the diamond substrate (seed crystal) 8 is placed on the substrate placement surface of the substrate support. The diamond substrate 8 is placed on the placement portion without any gap. In this state, the top surface 7d and the diamond surface of the substrate of the substrate surrounding portion of the substrate support a flush, the thickness t ₂ of the member 7b including top surface of the substrate surrounding portion, the thickness of the diamond substrate t ₁ is the same.

  With the method described above, the diamond substrate was placed on the substrate support, diamond was grown for 3 hours under the same conditions as in Example 1, and the grown crystal was taken out.

  As a result of measuring the thickness of the obtained diamond single crystal with a micrometer, the thickness increased by about 0.2 mm in the main growth direction.

  FIG.5 (b) is a schematic sectional drawing which shows the result of having observed the obtained diamond crystal with the optical microscope. As is apparent from this drawing, the shape of the diamond 9 grown on the surface of the diamond substrate 8 was almost smooth.

It is a schematic block diagram which shows schematically the internal structure of a microwave plasma CVD apparatus. Three examples (a), (b) and (c) of the diamond substrate support are shown, the upper diagram is a plan view, and the lower diagram is a central longitudinal front view. It is the elements on larger scale of the center longitudinal section front view of the diamond substrate support of Drawing 2 (c). FIG. 4 is a central longitudinal sectional front view schematically showing a state in which a diamond substrate is placed on a substrate support placing part in Examples 1 and 2, FIG. 4A is Example 1, and FIG. 4B is Example. The state of 2 is shown. It is drawing which shows typically the microscope picture of the longitudinal cross-section of the diamond crystal obtained in Example 1 and 2, FIG. 5 (a) is the diamond crystal obtained in Example 1, FIG.5 (b) is an Example. The diamond crystal obtained in 2 is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microwave plasma CVD apparatus, 2 Microwave power supply 3 Waveguide which propagates microwave, 4 Microwave introduction quartz window 5 Cavity resonator type reaction vessel, 5a Source gas introduction port 5b Exhaust port, 6 Cooling water inside Cooling stage 7 through which W passes Diamond substrate support, 7a Substrate mounting surface 7b of substrate support member including top surface of substrate surrounding portion, 7c Member 7d including substrate mounting surface of substrate support portion of substrate surrounding portion Top surface 7e inner wall surface 7f of substrate mounting portion member 8 for outer peripheral edge of substrate support 8 diamond substrate, 8a end of diamond substrate,
8b Central part of diamond substrate 9 Diamond growth part

Claims (8)

In a method of growing a diamond crystal on a diamond substrate by a microwave plasma CVD method,
The substrate support installed in the CVD apparatus is a support made of a conductive material having a substrate surrounding portion around the substrate mounting surface, and the substrate support including the substrate surrounding portion is integral or It is a structure in which a predetermined thickness portion can be separated from the top surface of the substrate surrounding portion,
A diamond manufacturing method characterized in that diamond growth is performed by controlling a shape of a diamond growth surface by adjusting a thickness of a member including a top surface of the substrate surrounding portion. The method according to claim 1, wherein the growth of the end face of the diamond substrate is suppressed by increasing the thickness of the member including the top surface of the substrate surrounding portion. The method according to claim 1, wherein the growth of the end face of the diamond substrate is promoted by reducing the thickness of the member including the top surface of the substrate surrounding portion. The top surface of the substrate surrounding portion of the substrate support is substantially flush with the surface of the diamond substrate, and the thickness of the member including the top surface of the substrate surrounding portion is made larger than the thickness of the diamond substrate, thereby growing the diamond. The method according to claim 1, wherein the surface has a convex shape. The top surface of the substrate surrounding portion in the substrate support is substantially flush with the surface of the diamond substrate, and the thickness of the member including the top surface of the substrate surrounding portion in the substrate support is substantially the same as the thickness of the diamond substrate. The method according to claim 1, wherein the shape of the diamond growth surface is made flat. The top surface of the substrate surrounding portion in the substrate support is substantially flush with the surface of the diamond substrate, and the thickness of the member including the top surface of the substrate surrounding portion in the substrate support is made smaller than the thickness of the diamond substrate. The method according to claim 1, wherein the shape of the diamond growth surface is made concave. The method according to claim 4, wherein the difference in height between the top surface of the substrate surrounding portion and the surface of the diamond substrate in the substrate support is less than 0.3 mm.   A substrate support made of a conductive material provided with a substrate surrounding portion around a substrate mounting surface used in the method according to claim 1, wherein the substrate support including the substrate surrounding portion is integrated. A substrate support for producing diamond by a microwave plasma CVD method having a structure in which a predetermined thickness portion is separable from the top surface.

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