JP6887893B2 - Manufacturing method of single crystal diamond, single crystal diamond composite and single crystal diamond substrate - Google Patents

Description

The present invention relates to a method for producing single crystal diamond, a single crystal diamond composite, and a single crystal diamond substrate. In particular, the present invention relates to a method for producing single crystal diamond used for cutting tools, optical parts, semiconductor materials, heat radiating parts, etc., a single crystal diamond composite, and a single crystal diamond substrate.

Conventionally, a single crystal diamond substrate has been manufactured by using a chemical vapor deposition (CVD) method. For example, by epitaxially growing a single crystal diamond layer on the main surface of the seed substrate, a single crystal diamond substrate having a main surface having the same plane orientation as the main surface of the seed substrate is manufactured (Japanese Patent Laid-Open No. 11-). See Japanese Patent Application Laid-Open No. 1392 (Patent Document 1), Japanese Patent Application Laid-Open No. 2005-225746 (Patent Document 2), and Japanese Patent Application Laid-Open No. 2003-277183 (Patent Document 3).

The plane orientation of the main surface of the single crystal diamond substrate is appropriately selected according to the form to which the single crystal diamond substrate is applied. In general, single crystal diamonds tend to grow on the (100) plane of the seed substrate. Therefore, in order to obtain a single crystal diamond substrate having a plane orientation other than the (100) plane as the main plane, the single crystal diamond is thickly grown on the (100) plane of the seed substrate, and then the desired plane orientation is obtained. Need to disconnect. In this case, it takes time and effort for processing.

In Japanese Patent Application Laid-Open No. 2013-53051 (Patent Document 4), in order to save the labor of the above processing, a plurality of parallel linear grooves are formed on the main surface of the seed substrate by a laser, and a plurality of parallel linear grooves are formed on the main surface. A manufacturing method for epitaxially growing single crystal diamond is disclosed. According to the manufacturing method, a diamond composite obtained by bonding a plurality of single crystal diamond substrates by a bonding layer interposed between the main surfaces thereof can be obtained. The plane orientation of the main surface of the plurality of single crystal diamond substrates is different from the plane orientation of the main surface of the seed substrate. The bonding layer is composed of polycrystalline diamond or non-diamond carbon, and loosely bonds single crystal diamond substrates to each other. Therefore, the single crystal diamond substrates can be easily separated from each other.

Japanese Unexamined Patent Publication No. 11-1392 Japanese Unexamined Patent Publication No. 2005-225746 Japanese Unexamined Patent Publication No. 2003-277183 Japanese Unexamined Patent Publication No. 2013-53051 Japanese Unexamined Patent Publication No. 2007-191362

In the production method described in Patent Document 4, it is necessary to appropriately adjust the width and depth of the grooves formed in the seed substrate in order to form a bonding layer other than single crystal diamond between a plurality of single crystal diamond substrates. .. At this time, it is necessary to be careful not to crack the seed substrate when the seed substrate is conveyed after the groove is formed, which makes it difficult to handle the seed substrate.

In addition, since a step of removing a bonding layer that is not a single crystal diamond is required, productivity tends to decrease.

In view of the above points, the present disclosure discloses a method for producing a single crystal diamond in which the seed substrate is easy to handle and has high productivity, and a single crystal diamond composite and a single crystal tiremond substrate produced by the production method. The purpose is to provide.

The method for producing a single crystal diamond according to one aspect of the present disclosure includes a step of linearly forming a metal film in which carbon can be dissolved on a main surface of a seed substrate of a single crystal diamond, and a method of linearly forming a metal film in which carbon can be dissolved. By heat-treating the seed substrate in a gas containing at least one of the molecules, the seed substrate is eroded by the metal film to form a groove on the main surface, and after the groove is formed, the metal film is formed on the main surface. A step of forming a single crystal diamond layer by a chemical vapor phase growth method is provided on the region not formed.

The single crystal diamond composite according to one aspect of the present disclosure comprises a single crystal diamond seed substrate having grooves formed on the main surface and a single crystal diamond layer formed on a portion of the main surface excluding the grooves. Be prepared. The single crystal diamond complex contains a metal film in which carbon is dissolved on the surface of the groove in the seed substrate.

The surface of the single crystal diamond substrate according to one aspect of the present disclosure includes a pair of main surfaces. On at least one of the pair of main surfaces, first growth fringes showing changes in at least one of the defect amount and the impurity concentration are observed. The first growth fringes are arranged along the first direction in at least one main surface. On at least one main surface, the first growth fringe observed on one end side in the first direction is linear, and the first growth fringe observed on the other end side in the first direction is one end in the first direction. It is convex toward the other end. The length from one end to the other end in the first direction on at least one main surface is 0.5 mm or more.

The surface of the single crystal diamond substrate according to another aspect of the present disclosure includes a pair of main surfaces. On at least one of the pair of main surfaces, first growth fringes showing changes in at least one of the defect amount and the impurity concentration are observed. The first growth fringes are arranged along the first direction in at least one main surface. A second growth fringe showing a change in at least one of the defect amount and the impurity concentration is observed in the cross section when the single crystal diamond substrate is cut in a plane parallel to the first direction and perpendicular to the pair of main planes. .. The second growth fringes are arranged along the second direction in the cross section. In the cross section, the second growth fringe observed on one end side in the second direction is linear, and the second growth fringe observed on the other end side in the second direction is from one end to the other end in the second direction. It is a convex shape facing. The length from one end to the other end in the second direction in the cross section is 0.5 mm or more.

According to the above, it is possible to provide a method for producing a single crystal diamond which is easy to handle and has high productivity, and a single crystal diamond composite and a single crystal tiremond substrate produced by the production method. it can.

It is a figure which shows typically the manufacturing method of the single crystal diamond which concerns on this embodiment. It is a figure which shows the off direction and the off angle with respect to the reference plane of a target plane. It is a figure which shows an example of the microwave plasma apparatus. It is a figure which shows typically the modification of the manufacturing method of a single crystal diamond. It is sectional drawing which shows an example of the single crystal diamond complex which concerns on this embodiment. It is a perspective view which shows an example of the single crystal diamond substrate which concerns on this embodiment. It is a top view which shows the main surface in which the 1st growth fringe is observed. It is a figure which shows the cross section when the single crystal diamond substrate is cut in the plane which is parallel to the 1st direction and is perpendicular to a pair of main planes. It is a figure which shows a part of growth fringes observed in the cross section of a single crystal diamond layer when a single crystal diamond layer is grown with a thickness of 0.5 mm or more without forming a metal film on a seed substrate. It is a figure which shows the flow of the active species in the conventional production method. It is a figure which shows the flow of the active species in the manufacturing method which concerns on this embodiment. It is a figure which shows the flow of the active species when viewed from the direction different from FIG. It is a figure which shows an example of a cutting tool. It is a top view which shows the tip of a cutting tool. FIG. 6 is a cross-sectional view taken along the line XX shown in FIG. It is a perspective view which shows another example of a single crystal diamond substrate.

[Explanation of Embodiments of the Invention]
First, embodiments of the present disclosure will be listed and described. In this specification, the notation in the form of "M to N" means the upper and lower limits of the range (that is, M or more and N or less), and there is no description of the unit in M and the unit is described only in N. , The unit of M and the unit of N are the same.

[1] The method for producing a single crystal diamond according to the present disclosure includes a step of linearly forming a metal film in which carbon can be dissolved on a main surface of a seed substrate of a single crystal diamond, and a method of forming hydrogen atoms and oxygen atoms. By heat-treating the seed substrate in a gas containing at least one of the molecules, the seed substrate is eroded by the metal film to form a groove on the main surface, and after the groove is formed, the metal film is formed on the main surface. A step of forming a single crystal diamond layer by a chemical vapor phase growth method is provided on the region not formed. Here, the "linear" includes not only a line whose width is infinitely narrower than its length, but also a strip whose ratio (length / width) is 2 or more.

According to the above configuration, by heat-treating the seed substrate in a gas of a molecule containing at least one of a hydrogen atom and an oxygen atom, the carbon of the portion of the seed substrate in contact with the metal film is dissolved in the metal film. .. The carbon dissolved in the metal film moves to the surface of the metal film and is released into the surrounding gas. As a result, the seed substrate in the portion where the metal film is formed is eroded, and a groove is formed in the seed substrate. Then, a single crystal diamond layer is formed by epitaxial growth using a chemical vapor deposition method on the region where the metal film is not formed. Here, it is possible to carry out the step of forming the groove and the step of forming the single crystal diamond layer in the same chamber. Therefore, it is not necessary to transfer the seed substrate into the chamber after forming the groove with respect to the seed substrate. As a result, it is not necessary to worry about cracking of the seed substrate during transportation after the groove is formed, and the seed substrate can be easily handled. Further, a seed substrate thinner than the manufacturing method described in Patent Document 4 can be used, and the options for the seed substrate are expanded. It is also possible to control the depth of the groove to 1/10 or less of the thickness of the seed substrate. In this case, the risk of cracking of the substrate becomes extremely small, and the seed substrate can be easily handled. At this time, it is not always necessary to form the groove and the single crystal diamond layer in the same chamber.

As a method for heat-treating the seed substrate in a gas having a molecule containing at least one of a hydrogen atom and an oxygen atom, it is convenient to use a hydrogen plasma or a plasma containing an oxygen atom. It is not necessary that the gas composition forming the groove and the gas composition forming the single crystal diamond layer match. When there is no plasma, the seed substrate or the gas may be heated in a gas of a molecule containing at least one of a hydrogen atom and an oxygen atom in the atmosphere to supply heat to the seed substrate. Since grooves are formed by the thermal reaction with or without plasma, the greater the heat supplied to the seed substrate, the easier it is for the grooves to be formed.

Further, a metal film is present on the surface of the groove formed on the main surface of the seed substrate. Therefore, the epitaxial growth of the single crystal diamond on the groove is suppressed. In the case of a groove in which diamond is exposed as in Patent Document 4, the groove is filled with a bonding layer, and a step of removing the bonding layer is required. However, according to the above configuration, it is difficult to form the bonding layer, and the step of removing the bonding layer becomes unnecessary, so that the productivity can be improved.

As described above, it is possible to realize a method for producing a single crystal diamond which is easy to handle and has high productivity.

[2] In the step of forming the metal film linearly, the metal film is formed in a linear or lattice shape so that the region has a rectangular shape. The off angle of the main surface with respect to the (001) surface is 1 degree or more and 10 degrees or less. The angle formed by the in-plane off direction projected on the main surface with respect to the (001) plane of the main surface and the long side of the region is equal to or less than the inferior angle formed by the long side and the diagonal line of the region. As a result, the single crystal diamond layer can be efficiently and thickly grown on the main surface of the seed substrate. As described above, "linear" also includes strips having a length / width of 2 or more.

[3] In the step of forming the metal film linearly, the metal film is formed in a linear or lattice shape so that the region has a rectangular shape. The thickness of the single crystal diamond layer is longer than the short side length of the region. As a result, the plane orientation of the main surface of the substrate (single crystal diamond substrate) composed of the single crystal diamond layer is different from the plane orientation of the main surface of the seed substrate. That is, it is possible to easily manufacture a single crystal diamond substrate having a main surface having a plane orientation different from that of the main surface of the seed substrate. As described above, "linear" also includes strips having a length / width of 2 or more.

[4] The metal film contains a metal exhibiting ferromagnetism. The metal film also erodes the seed substrate even in the early stages of epitaxial growth of single crystal diamond. Therefore, the metal film wraps around the boundary between the single crystal diamond layer and the seed substrate. Thereby, the orientation of the single crystal diamond layer can be determined by utilizing the ferromagnetism exhibited by the metal contained in the metal film.

[5] In the step of forming the single crystal diamond layer, a plurality of single crystal diamond layers are formed on the main surface. The method for producing single crystal diamond further includes a step of separating the plurality of single crystal diamond layers from each other. A substrate (single crystal diamond substrate) can be formed by separated single crystal diamond layers. Thereby, a plurality of single crystal diamond substrates can be obtained from one seed substrate.

[6] The single crystal diamond composite according to the present disclosure comprises a single crystal diamond seed substrate having grooves formed on the main surface and a single crystal diamond layer formed on a portion of the main surface excluding the grooves. Be prepared. The single crystal diamond complex contains a metal film in which carbon is dissolved on the surface of the groove in the seed substrate.

The single crystal diamond complex having the above structure is obtained by the above production method. Therefore, the seed substrate is easy to handle, and the productivity of the single crystal diamond complex is high.

[7] The surface of the single crystal diamond substrate according to the present disclosure includes a pair of main surfaces. On at least one of the pair of main surfaces, first growth fringes showing changes in at least one of the defect amount and the impurity concentration are observed. The first growth fringes are arranged along the first direction in at least one main surface. On at least one main surface, the first growth fringe observed on one end side in the first direction is linear, and the first growth fringe observed on the other end side in the first direction is one end in the first direction. It is convex toward the other end. The length from one end to the other end in the first direction on at least one main surface is 0.5 mm or more.

In the above-mentioned manufacturing method, the single crystal diamond substrate having the above configuration has a metal film formed so as to be located between the short sides of a plurality of rectangular regions, and the thickness of the single crystal diamond layer is 0.5 mm or more. Obtained by Therefore, the seed substrate is easy to handle, and the productivity of the single crystal diamond substrate is high.

The cutting edge of a cutting tool is often machined into a curved surface. When the single crystal diamond substrate having the above configuration is applied to a cutting tool, the bending of the tip of the cutting edge is observed on the other end side of the main surface of the single crystal diamond substrate in the first direction. Can be adjusted to. As a result, the amount of defects and the concentration of impurities in the portion of the single crystal diamond substrate that comes into contact with the work material can be made uniform. As a result, it is possible to prevent streaks from being formed on the work material due to subtle differences in the crystalline state. Further, it is possible to suppress chipping of the single crystal diamond substrate during cutting.

[8] The surface of the single crystal diamond substrate includes a side surface of at least one main surface that intersects one end in the first direction. A second growth fringe showing a change in at least one of the defect amount and the impurity concentration is observed in the cross section when the single crystal diamond substrate is cut in a plane parallel to the first direction and perpendicular to the pair of main planes. .. The second growth fringes are arranged along the second direction in the cross section. One end of the cross section in the second direction is the line of intersection between the cross section and the above side surface. In the cross section, the second growth fringe observed on one end side in the second direction is linear, and the second growth fringe observed on the other end side in the second direction is from one end to the other end in the second direction. It is a convex shape facing.

The single crystal diamond substrate having the above configuration is obtained by forming a metal film so as to be located between the long sides of a plurality of rectangular regions in the above manufacturing method.

When the single crystal diamond substrate having the above configuration is applied to a cutting tool, the main surface of the single crystal diamond substrate can be used as a rake face, and the side surface including the other end in the second direction in the cross section can be used as a flank. As a result, the convex second growth fringes observed on the other end side in the second direction in the cross section are located at the corners from the rake face to the flank face. As a result, the amount of defects and the concentration of impurities in the cutting edge portion in contact with the work material can be made uniform from the rake face to the flank surface, and it is possible to suppress the formation of streaks on the work material due to the slight difference in the crystal state. .. Further, it is possible to suppress chipping of the single crystal diamond substrate during cutting.

[9] The above side surface has a flat rectangular shape. The off angle of the side surface with respect to the (001) surface is 1 degree or more and 10 degrees or less. The angle formed by the in-plane off direction projected on the side surface with respect to the (001) surface of the side surface and the long side of the side surface is equal to or less than the inferior angle formed by the long side and the diagonal line of the side surface.

The single crystal diamond substrate having the above configuration can be obtained by the manufacturing method of the above [2]. Therefore, it is efficiently manufactured from the seed substrate.

[10] The distance between the pair of main surfaces becomes shorter from one end in the first direction to the other end.

According to the above configuration, when a metal film is formed so as to be located between the long sides of a plurality of rectangular regions, the two single crystal diamond substrates manufactured by sandwiching the metal film are not joined at the time of manufacture. .. Thereby, the single crystal diamond substrate can be easily manufactured.

[11] The surface of the single crystal diamond substrate according to another aspect of the present disclosure includes a pair of main surfaces. On at least one of the pair of main surfaces, first growth fringes showing changes in at least one of the defect amount and the impurity concentration are observed. The first growth fringes are arranged along the first direction in at least one main surface. A second growth fringe showing a change in at least one of the defect amount and the impurity concentration is observed in the cross section when the single crystal diamond substrate is cut in a plane parallel to the first direction and perpendicular to the pair of main planes. .. The second growth fringes are arranged along the second direction in the cross section. In the cross section, the second growth fringe observed on one end side in the second direction is linear, and the second growth fringe observed on the other end side in the second direction is from one end to the other end in the second direction. It is a convex shape facing. The length from one end to the other end in the second direction in the cross section is 0.5 mm or more.

In the above-mentioned manufacturing method, the single crystal diamond substrate having the above configuration has a metal film formed so as to be located between the long sides of a plurality of rectangular regions, and the thickness of the single crystal diamond layer is 0.5 mm or more. Obtained by Therefore, the seed substrate is easy to handle, and the productivity of the single crystal diamond substrate is high.

When the single crystal diamond substrate having the above configuration is applied to a cutting tool, the main surface of the single crystal diamond substrate can be used as a rake face, and the side surface including the other end in the second direction in the above cross section can be used as a flank. As a result, the convex second growth fringes observed on the other end side in the second direction in the cross section are located at the corners from the rake face to the flank face. As a result, the amount of defects and the concentration of impurities in the cutting edge portion in contact with the work material can be made uniform from the rake face to the flank surface, and it is possible to suppress the formation of streaks on the work material due to the slight difference in the crystal state. .. Further, it is possible to suppress chipping of the single crystal diamond substrate during cutting.

[12] The surface of the single crystal diamond substrate includes a flat rectangular side surface including one end in the second direction in the cross section. The off angle of the side surface with respect to the (001) surface is 1 degree or more and 10 degrees or less. The angle formed by the in-plane off direction projected on the side surface with respect to the (001) surface of the side surface and the long side of the side surface is equal to or less than the inferior angle formed by the long side and the diagonal line of the side surface.

The single crystal diamond substrate having the above configuration can be obtained by the manufacturing method of the above [2]. Therefore, it is efficiently manufactured from the seed substrate.

[13] The distance between the pair of main surfaces becomes shorter from one end to the other end in the second direction.

According to the above configuration, when a metal film is formed so as to be located between the long sides of a plurality of rectangular regions, the two single crystal diamond substrates manufactured by sandwiching the metal film are not joined at the time of manufacture. .. Thereby, the single crystal diamond substrate can be easily manufactured.

[14] The single crystal diamond substrate contains a metal exhibiting ferromagnetism in at least a part of the side surface.

The single crystal diamond substrate having the above configuration can be obtained by the above-mentioned production method [4]. According to the above configuration, the orientation of the single crystal diamond substrate can be easily determined by bringing a magnet or the like closer to each other.

[15] The off angle of at least one main surface with respect to the (110) surface is 0 degrees or more and 20 degrees or less.

The single crystal diamond substrate having the above configuration can be obtained by the above-mentioned production methods [2] and [3]. Therefore, a single crystal diamond substrate having a (110) main surface can be easily obtained.

[Details of Embodiments of the present invention]
Hereinafter, an embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described. However, this embodiment is not limited to these. In the drawings used in the following embodiments, the same reference numerals represent the same parts or equivalent parts.

<Manufacturing method of single crystal diamond>
FIG. 1 is a diagram schematically showing a method for producing a single crystal diamond according to the present embodiment. As shown in FIG. 1, the method for producing a single crystal diamond includes a first step of preparing a seed substrate 30, a second step of forming a metal film 40 on the seed substrate 30, and forming a groove 36 on the seed substrate 30. The third step of forming the single crystal diamond layer 50 on the plurality of regions 34 in which the metal film 40 is not formed on the seed substrate 30, and the single crystal formed on the plurality of regions 34. It includes a fifth step of separating the diamond layers 50 from each other to obtain a single crystal diamond substrate 10. The method for producing single crystal diamond may include the above-mentioned second to fourth steps, and the first step and the fifth step may be omitted.

<< First step >>
First, a seed substrate 30 for epitaxially growing single crystal diamond by a chemical vapor deposition method is prepared. The seed substrate 30 is made of single crystal diamond. As the seed substrate 30, type I single crystal diamond or type II single crystal diamond produced by a high temperature and high pressure synthesis method may be used, or a single crystal diamond produced by a chemical vapor deposition method may be used. In particular, when single crystal diamond produced by the chemical vapor deposition method is used as the seed substrate 30, the difference in physical properties between the seed substrate 30 and the single crystal diamond layer 50 obtained by epitaxial growth is small, which is preferable.

The thickness of the seed substrate 30 is preferably 30 μm or more, and more preferably 50 μm or more. As a result, deformation or damage of the seed substrate 30 during handling can be suppressed. The upper limit of the thickness of the seed substrate 30 is not particularly limited, but in consideration of the manufacturing cost of the seed substrate 30, it is preferably 500 μm or less, and preferably 200 μm or less.

In order to efficiently and thickly form the single crystal diamond layer 50 on the main surface 32 of the seed substrate 30, the main surface 32 of the seed substrate 30 is preferably a (001) surface. Here, the "main surface" is the surface having the largest area on the surface of the substrate. Further, in the single crystal diamond, the "(001) plane" is equivalent to the "(100) plane" and the "(010) plane". In order to further enhance the crystal homogeneity of the single crystal diamond layer 50, the off angle of the main surface 32 of the seed substrate 30 with respect to the (001) surface is preferably 1 degree or more and 10 degrees or less.

The off direction of the main surface 32 of the seed substrate 30 with respect to the (001) plane is set according to the plane orientation of the main surface 11 of the single crystal diamond substrate 10 obtained in the fifth step.

FIG. 2 is a diagram showing an off direction a1 and an off angle θ with respect to the reference surface S2 of the target surface S1. The "off direction" (indicated by reference numeral a1 in FIG. 2) with respect to the reference surface S2 (for example, (001) surface) of the target surface S1 (for example, the main surface 32) is the normal direction a2 (for example, <. 001> direction) refers to the direction in which the normal direction n of the target surface S1 is inclined. Specifically, the off direction a1 is indicated by the direction of a vector obtained by projecting (projecting) the normal direction n from the normal direction a2 of the reference plane S2 onto the reference plane S2. Further, in the following, the direction in which the off direction a1 is projected onto the target surface S1 is referred to as an “in-plane off direction” (indicated by reference numeral a11 in FIG. 2). The off angle θ is an angle formed by the normal direction n of the target surface S1 and the normal direction a2 of the reference surface S2, and is an angle formed by the off direction a1 and the target surface S1.

For example, when it is desired to manufacture the single crystal diamond substrate 10 having the (110) plane as the main surface 11 in the fifth step, the off direction of the main surface 32 of the seed substrate 30 with respect to the (001) plane is the <1-10> direction or. It is set in the <-110> direction.

<< Second step >>
Returning to FIG. 1, the second step is a step of linearly forming a metal film 40 in which carbon can be dissolved on the main surface 32 of the seed substrate 30 of the single crystal diamond. The metal film 40 contains a metal element. Here, the metal element refers to all elements other than rare gas elements, group 17 elements (fluorine, etc.), H, B, C, N, O, Si, P, S, As, Se, and Te. ..

The metal film 40 preferably contains any one of Fe, Ni, Co, Mn, and Pt, more preferably contains a metal exhibiting ferromagnetism, and contains, for example, at least one of Fe, Ni, and Co. The metal film 40 may be a metal complex containing at least one of Fe, Ni, and Co as a main component.

In the second step, it is preferable to form the metal film in a linear or lattice shape so that the region 34 in which the metal film 40 is not formed has a rectangular shape. The left side of FIG. 1 shows the case where the metal film 40 is formed in a grid pattern, and the right side of FIG. 1 shows the case where the metal film 40 is formed in a straight line. Thin-film deposition or sputtering can be used as a method for forming the metal film 40 on the main surface 32 of the seed substrate 30. Specifically, a metal mask patterned in a linear or lattice pattern is arranged on the main surface 32 of the seed substrate 30, and the metal film 40 is formed by vapor deposition or sputtering. Alternatively, a linear or lattice-shaped metal film 40 is formed by forming a metal film on the entire main surface 32 of the seed substrate 30 by vapor deposition or sputtering and removing an unnecessary metal film by photolithography or laser. Can be formed.

When the region 34 has a rectangular shape, the long side direction of the region 34 is set according to, for example, the plane orientation of the main surface 11 of the single crystal diamond substrate 10 obtained in the fifth step. When it is desired to manufacture the single crystal diamond substrate 10 having the (110) plane as the main plane 11 on the main plane 32 which is the (001) plane, the long side direction of the rectangular region 34 is the (110) of the seed substrate 30. It is set in the direction parallel to the surface.

Further, when the off angle of the main surface 32 of the seed substrate 30 with respect to the (001) surface is 1 degree or more and 10 degrees or less, the off direction of the main surface 32 with respect to the (001) surface is projected onto the main surface 32. The angle formed by the long side of the rectangular region 34 is preferably equal to or less than the inferior angle formed by the long side of the region 34 and the diagonal line of the region 34.

The width of the metal film 40 is preferably 0.1 μm or more. When the width of the metal film 40 is 0.1 μm or more, the groove 36 can be stably formed in the seed substrate 30 in the third step. The width of the metal film 40 is preferably 500 μm (0.5 mm) or less. When the width of the metal film 40 is 500 μm or less, the yield of the single crystal diamond substrate 10 with respect to the seed substrate 30 can be improved.

<< Third step >>
In the third step, the seed substrate 30 is heat-treated in a gas of a molecule containing at least one of a hydrogen atom and an oxygen atom, so that the seed substrate 30 is eroded by the metal film 40 to form a groove 36 on the main surface 32. It is a process. For example, the seed substrate 30 is installed in a microwave plasma device, and heat is supplied to the seed substrate 30 by generating hydrogen plasma or plasma containing oxygen atoms around the seed substrate 30, and a groove 36 is formed in the main surface 32. Should be formed. Alternatively, the seed substrate 30 or the gas may be heated in a gas of a molecule containing at least one of a hydrogen atom and an oxygen atom to supply heat to the seed substrate 30.

FIG. 3 is a diagram showing an example of a microwave plasma device. As shown in FIG. 3, the microwave plasma apparatus 80 includes a chamber 81, a microwave power supply 82 for supplying microwaves to the chamber 81, and a waveguide 83 connecting the microwave power supply 82 and the chamber 81. A microwave introduction window 84 for introducing microwaves from the waveguide 83 into the chamber 81, a support base 85 for supporting the seed substrate 30, and a gas supply pipe for supplying the raw material gas into the chamber 81. It has 86 and a gas discharge pipe 87 that discharges gas from the chamber 81. A gas of a molecule containing at least one of a hydrogen atom and an oxygen atom is supplied from the gas supply pipe 86, and the microwave is introduced from the microwave introduction window 84, so that plasma 88 is generated around the seed substrate 30. Heat is supplied to the seed substrate 30 by the plasma 88.

As described above, the metal film 40 can dissolve carbon in a solid solution. The metal film 40 heat-treated in a gas of a molecule containing at least one of a hydrogen atom and an oxygen atom dissolves carbon in a portion of the seed substrate 30 in contact with the metal film 40. The carbon dissolved in the metal film 40 moves to the surface of the metal film 40 and is released into the surrounding gas. In this way, the portion of the main surface 32 of the seed substrate 30 on which the metal film 40 is formed is eroded. On the other hand, the region 34 in which the metal film 40 is not formed remains as it is without being eroded. Therefore, a step is formed between the portion where the metal film 40 is formed and the portion where the metal film 40 is not formed, and the groove 36 is formed at the portion where the metal film 40 is formed. On the surface of the groove 36 in the seed substrate 30, a metal film 40 in which carbon is dissolved is present.

<< 4th process >>
The fourth step is a step of forming the single crystal diamond layer 50 by the chemical vapor deposition method on the region 34 on the main surface 32 where the metal film 40 is not formed after the groove 36 is formed. By this step, a single crystal diamond complex 20 in which a plurality of single crystal diamond layers 50 are formed on the main surface 32 of the seed substrate 30 is obtained. The raw material gas is, for example, a methane-hydrogen mixed gas. As a growth method, a hot filament method, a combustion flame method, an arc jet method, or the like can be used, but in the present embodiment, a microwave plasma method is used in order to obtain high-quality diamond with less contamination of impurities.

In the microwave plasma method, a mixed gas of hydrogen and methane is introduced into the chamber 81 as a raw material gas at a methane / hydrogen gas flow rate ratio of 6% to 20%, and plasma is generated by microwaves. In the generated plasma, there are active species containing carbon. The single crystal diamond layer 50 is formed by epitaxially depositing the active species on the region 34.

The methane concentration in the raw material gas is appropriately set according to the plane orientation of the main surface 32 of the seed substrate 30 and the growth parameter (α). ^{The growth parameter (α) is represented by α = 3 0.5} × V001 / V111 when the growth rate of the (001) plane is V001 and the growth rate of the (111) plane is V111.

Since the metal film 40 is present on the surface of the groove 36, active species are not deposited and the epitaxial growth of single crystal diamond is suppressed. Therefore, the epitaxial growth conditions may be set in consideration of only the epitaxial growth of the single crystal diamond in the region 34. When the main surface 32 of the seed substrate 30 is the (001) surface, the epitaxial growth conditions may be set such that the growth parameter (α) is 2.8 or more.

When the region 34 is rectangular, the thickness of the single crystal diamond layer 50 formed on the region 34 is preferably longer than the short side length of the region 34.

The region 34 has a rectangular shape, and the angle formed by the in-plane off direction projected onto the main surface 32 with respect to the (001) plane of the main surface 32 and the long side of the region 34 is the long side of the region 34 and the diagonal line. When it is less than or equal to the inferior angle formed by, there are the following advantages. That is, in the fourth step, the elimination of atomic steps in the rectangular region 34 is suppressed, and the decrease in the growth rate of the single crystal diamond on the region 34 is suppressed.

When a decrease in the growth rate occurs in a part of the plurality of regions 34, the thickness of the single crystal diamond layer 50 formed on the partial region 34 is the thickness of the single crystal formed on the surrounding region 34. It is thinner than the thickness of the diamond layer 50. This reduces the yield of the single crystal diamond substrate. However, since the decrease in the growth rate is suppressed as described above, the single crystal diamond layer 50 having a desired thickness can be formed in all of the plurality of regions 34, and the decrease in the yield can be suppressed.

Further, when the region 34 has a rectangular shape, it is preferable that the width of the region 34 in the single crystal diamond layer 50 in the short side direction is gradually reduced as the growth progresses by appropriately adjusting the epitaxial growth conditions. As a result, it is possible to prevent the two adjacent single crystal diamond layers 50 from joining each other as the growth progresses. For example, by selecting epitaxial growth conditions with a growth parameter of 2.8 or higher, that is, by increasing the methane concentration to 8% or higher, or by lowering the temperature of the seed substrate 30 below 950 ° C., single crystal diamond. The width of the rectangular region 34 in the layer 50 in the short side direction can be gradually reduced. When the width in the short side direction is gradually reduced, if the thickness in the growth direction becomes larger than the width, it is considered that the electric field is concentrated like a lightning rod in the plasma in which the electric field exists. When the electric field is concentrated, the single crystal diamond layer 50 is not uniformly formed on the seed substrate 30, and the epitaxial growth may stop. However, in the present embodiment, since the concentration of the electric field is suppressed by setting the width of the metal film 40 to 500 μm or less, even if the width in the short side direction is gradually reduced, the thickness larger than the width is increased. The single crystal diamond layer 50 having can be grown.

<< Fifth step >>
As described above, in the fourth step, a plurality of single crystal diamond layers 50 are formed on the main surface 32. The fifth step is a step of separating the plurality of single crystal diamond layers 50 from each other. As a result, the single crystal diamond substrate 10 is manufactured. In this embodiment, as shown in FIG. 1, the seed substrate 30 is cleaved along the groove 36 to separate the plurality of single crystal diamond layers 50 from each other.

When the thickness of the single crystal diamond layer 50 is made longer than the short side length of the rectangular region 34 in the fourth step, the main surface 11 of the single crystal diamond substrate 10 becomes the side surface of the single crystal diamond layer 50. Therefore, it is possible to obtain a single crystal diamond substrate 10 having a main surface 11 having a surface orientation different from that of the main surface 32 of the seed substrate 30. For example, when the main surface 32 of the seed substrate 30 is the (001) plane and the long side of the rectangular region 34 is parallel to the (110) plane of the seed substrate, the (110) plane is the main surface 11. A crystalline diamond substrate 10 can be obtained. When a single crystal diamond is grown on the (110) plane of a seed substrate in order to obtain a single crystal diamond substrate having a (110) plane as a main plane, it is generally impossible to increase the concentration of impurities such as N. Therefore, conventionally, it has been difficult to obtain a single crystal diamond substrate containing impurities and having the (110) plane as the main plane. However, according to the production method of the present embodiment, since the single crystal diamond is grown on the (001) plane, the impurity concentration can be increased. Therefore, a single crystal diamond substrate 10 containing impurities and having the (110) plane as the main plane 11 can be easily obtained.

Further, in the fourth step, when the width of the rectangular region 34 in the single crystal diamond layer 50 in the short side direction is gradually reduced as the growth progresses, the off angle of the main surface 11 of the single crystal diamond substrate 10 with respect to the reference plane is increased. Can be increased. For example, the off angle of the main surface 11 of the single crystal diamond substrate 10 with respect to the (110) surface can be set to 5 to 20 degrees.

The surface of the single crystal diamond substrate 10 obtained in the fifth step may be polished if necessary. Usually, at least one of the pair of main surfaces with the largest area is flattened by polishing.

<Modified example of manufacturing method of single crystal diamond>
FIG. 4 is a diagram schematically showing a modified example of a method for producing single crystal diamond. As shown in FIG. 4, in the first step, the carbon ion implantation layer 38 may be formed by injecting carbon ions into the main surface 32 of the seed substrate 30. In this case, in the fifth step, the seed substrate 30 and the single crystal diamond layer 50 are separated by electrochemically etching the single crystal diamond composite 20 obtained in the fourth step in pure water. As a result, the separated single crystal diamond layer 50 becomes the single crystal diamond substrate 10.

In the case of the production method shown in FIG. 4, it is preferable to use a seed substrate 30 thicker than the seed substrate 30 used in the production method shown in FIG. 1 in order to form the carbon ion implantation layer 38.

<Single crystal diamond complex>
The single crystal diamond composite 20 according to the present embodiment is an intermediate product in the above method for producing single crystal diamond, and is produced by the above steps 2 to 4 (see FIGS. 1 and 4).

FIG. 5 is a cross-sectional view showing an example of the single crystal diamond complex according to the present embodiment. As shown in FIG. 5, the single crystal diamond composite 20 is formed on the single crystal diamond seed substrate 30 in which the groove 36 is formed on the main surface 32 and the region 34 on the main surface 32 excluding the groove 36. The single crystal diamond layer 50 is provided. The single crystal diamond complex 20 includes a metal film 40 in which carbon is solid-solved on the surface of the groove 36 in the seed substrate 30.

Since the metal film 40 is present on the surface of the groove 36, the growth of the single crystal diamond on the groove 36 is suppressed. Thereby, the epitaxial growth conditions suitable for forming the single crystal diamond layer 50 in the region 34 can be selected, and the productivity can be improved.

Further, the metal film 40 is exposed to a hydrogen plasma atmosphere before epitaxially growing the single crystal diamond, so that it can be solid-solved with carbon in the seed substrate 30 to easily form a groove 36 in the seed substrate 30. Since the single crystal diamond can be epitaxially grown immediately after the groove 36 is formed, it is not necessary to convey the seed substrate 30 in which the groove 36 is formed. As a result, the seed substrate 30 can be easily handled.

<Single crystal diamond substrate>
FIG. 6 is a perspective view showing an example of the single crystal diamond substrate 10 according to the present embodiment. FIG. 6 is obtained when the metal film 40 is formed in a grid pattern and the thickness of the single crystal diamond layer 50 is 0.5 mm or more, which is longer than the short side length of the rectangular region 34, in the above manufacturing method. The single crystal diamond substrate 10 is shown. Forming the metal film 40 in a grid pattern means that the metal film 40 is located between the short sides of the plurality of rectangular regions 34, and the metal film 40 is also located between the long sides of the plurality of rectangular regions 34. Means to do (see left side of FIGS. 1 and 4).

As shown in FIG. 6, the single crystal diamond substrate 10 is a rectangular parallelepiped. The rectangular parallelepiped single crystal diamond substrate 10 is obtained by polishing so that the surface becomes flat after the fifth step described above. The surface of the single crystal diamond substrate 10 includes a pair of main surfaces 11 and 12.

On at least one of the pair of main surfaces 11 and 12 (here, the polished and flattened main surface 11), a first growth fringe 17 showing a change in at least one of the defect amount and the impurity concentration is observed. .. The first growth fringes 17 are arranged along the first direction D1 in at least one main surface (here, the main surface 11). Here, the "first direction" is the direction of a straight line that intersects all of the first growth fringes 17 observed on the main surface 11 and the angle formed with the first growth fringes 17 is closest to 90 degrees. The first direction D1 roughly corresponds to the growth direction of the single crystal diamond.

When a single crystal diamond is epitaxially grown by a chemical vapor deposition method, at least one of the defect amount and the impurity concentration in the single crystal diamond depends on the atmosphere in the chamber 81. Therefore, if the atmosphere in the chamber 81 slightly fluctuates with time during epitaxial growth, at least one of the defect amount and the impurity concentration in the single crystal diamond fluctuates along the growth direction. Fluctuations in the amount of defects or the concentration of impurities are observed as annual ring-like stripes. Therefore, when the thickness of the single crystal diamond layer 50 is longer than the short side length of the rectangular region 34, the first growth fringes 17 arranged along the first direction D1 on the main surface 11 of the single crystal diamond substrate 10 Is observed. The first direction D1 corresponds to the direction in which the growth direction of the single crystal diamond is projected onto the main surface 11.

The surface of the single crystal diamond substrate 10 has a side surface 13 that intersects one end of the first direction D1 on the main surface 11, a side surface 14 that intersects the other end of the first direction D1 on the main surface 11, and the remaining side surfaces 15, 16 and are included. Since the thickness of the single crystal diamond layer 50 is 0.5 mm or more, which is longer than the short side length of the rectangular region 34, the distance from the side surface 13 to the side surface 14 is 0.5 mm or more. That is, the length from one end to the other end of the first direction D1 on the main surface 11 is 0.5 mm or more. The upper limit of the length from one end to the other end of the first direction D1 on the main surface 11 is not particularly limited.

Changes in at least one of the amount of defects and the concentration of impurities are the intensity of photoluminescence (PL), the intensity of cathode luminescence (CL), the secondary electron intensity of the electron microscope, the backscattered electron intensity of the electron microscope, and the absorption current intensity of the electron microscope. Shown as either difference. Therefore, the first growth fringe 17 is a pixel having equal intensity in any mapping image of PL intensity, CL intensity, secondary electron intensity of electron microscope, backscattered electron intensity of electron microscope, and absorption current intensity of electron microscope. Shown as a group muscle. In the mapping image, pixels having a large intensity difference from adjacent pixels are easily visible. Therefore, the mapped image may be subjected to image processing using a differential filter, and the streaks in which the pixels having the maximum or minimum differential value are continuous may be specified as the first growth fringe 17.

When a mapping image of PL or CL intensity is obtained under conditions such as room temperature, near the dry ice sublimation temperature, near the liquid nitrogen boiling point temperature, and at a low temperature of 40K or less, fluctuations in the amount of defects and impurity concentration are clearly shown in the mapping image. It will be reflected. The excitation light of PL is preferably a short wavelength of 600 nm or less, more preferably 550 nm or less, and further preferably 500 nm or less. The secondary electron intensity, backscattered electron intensity, and absorbed current intensity can be evaluated with a scanning electron microscope at room temperature or at a temperature from room temperature to the boiling temperature of liquid nitrogen. These measuring means are effective as means for determining whether or not the single crystal diamond substrate is obtained by the manufacturing method of the present embodiment.

As shown in FIG. 6, on the main surface 11 of the single crystal diamond substrate 10, the first growth fringe 17 observed on one end side (side surface 13 side) of the first direction D1 is linear and is in the first direction. The first growth fringe 17 observed on the other end side (side surface 14 side) of the above is a convex shape from one end in the first direction toward the other end.

Whether the first growth fringe 17 is linear or convex is determined as follows. FIG. 7 is a plan view showing a main surface in which the first growth fringe is observed. In FIG. 7, k first growth stripes 17 (17-1 to 17-k) are shown. In the first growth fringe 17 to be judged (the first growth fringe 17-1 is the judgment target in the figure), one end in the direction perpendicular to the first direction D1 is set as a point a, the other end is set as a point b, and the middle Let the point c be the point c, and let the midpoint of the line segment connecting the points a and b be the point d. Let xc and xd be the coordinates of the foot of the perpendicular line drawn from the points c and d to the coordinate axis X parallel to the first direction, respectively. The coordinate axis X is set so that the coordinates of the other end are larger than the coordinates of one end of the first direction D1 on the main surface of the single crystal diamond substrate. When | xc−xd | ≦ 5 μm is satisfied, it is determined that the first growth fringe is linear. When xd <xc and | xc-xd |> 5 μm are satisfied, it is determined that the first growth fringe 17 is convex from one end to the other end in the first direction D1. When xd> xc and | xc-xd |> 5 μm are satisfied, it is determined that the first growth fringe 17 is convex from the other end to one end in the first direction D1.

FIG. 8 is a diagram showing a cross section 18 when a single crystal diamond substrate is cut in a plane parallel to the first direction D1 and perpendicular to the pair of main surfaces 11 and 12. As shown in FIG. 8, the defect amount and the impurity concentration are shown in the cross section 18 when the single crystal diamond substrate 10 is cut in a plane parallel to the first direction D1 and perpendicular to the pair of main surfaces 11 and 12. A second growth fringe 19 showing at least one change is observed. The second growth fringes are arranged along the second direction D2 in the cross section 18. Here, the "second direction" is the direction of a straight line that intersects all of the second growth fringes 19 observed in the cross section 18 and the angle formed with the second growth fringes 19 is closest to 90 degrees. The second direction D2 roughly corresponds to the growth direction of the single crystal diamond. That is, the second direction D2 corresponds to the direction in which the growth direction of the single crystal diamond is projected onto the cross section 18. One end of the second direction D2 in the cross section 18 is a line of intersection between the cross section 18 and the side surface 13. The other end of the cross section 18 in the second direction is the line of intersection between the cross section 18 and the side surface 14.

As shown in FIG. 8, in the cross section 18, the second growth fringe 19 observed on one end side (side surface 13 side) of the second direction D2 is linear, and the other end side (side surface) of the second direction D2. The second growth fringe 19 observed on the 14th side) is convex from one end to the other end in the second direction D2. Whether the second growth fringe 19 is linear or convex is determined by the same method as that of the first growth fringe 17.

The reason why the first growth fringe 17 and the second growth fringe 19 have the above-mentioned shapes will be described below. FIG. 9 shows a part of the growth fringes 119 observed in the cross section of the single crystal diamond layer 50 when the single crystal diamond layer 50 is grown to a thickness of 0.5 mm or more without forming the metal film 40 on the seed substrate 30. It is a figure which shows. FIG. 10 is a diagram showing a flow of active species in the production method described in Patent Document 4. FIG. 11 is a diagram showing a flow of active species in the production method according to the present embodiment. FIG. 12 is a diagram showing a flow of active species in the production method according to the present embodiment when viewed from a direction different from that of FIG. FIG. 10 shows a cross section when the single crystal diamond layer 50 is cut on a plane perpendicular to the main surface of the seed substrate 30 and perpendicular to the groove 136 of the seed substrate 30. FIG. 11 shows a cross section when the single crystal diamond layer 50 is cut on a plane perpendicular to the main surface of the seed substrate 30 and parallel to the short side of the rectangular region 34. FIG. 12 shows the side surface of the single crystal diamond layer 50 as a plane perpendicular to the main surface of the seed substrate 30 and parallel to the long side of the rectangular region 34.

As shown in FIG. 9, when the single crystal diamond layer 50 having a thickness of 0.5 mm or more was formed on the seed substrate 30 without forming the metal film 40, the end portion was raised from the central portion at the growth end stage. Concave growth fringes 119 are observed. This is because, as described in Japanese Patent Application Laid-Open No. 2007-191362 (Patent Document 5), the temperature of the end portion is higher than that of the central portion, and the growth of the end portion is larger than that of the central portion. is there.

According to Patent Document 5, by making the gap between the end face of the seed substrate 30 and the support base 85 less than 0.5 mm, the growth rate of the end portion is made slower than the growth rate of the central portion, and the shape is convex. Growth fringes are formed. However, this phenomenon is observed when the thickness of the single crystal diamond layer 50 is 0.3 mm or less. When the thickness of the single crystal diamond layer 50 exceeds 0.3 mm, the influence of the gap between the end face of the seed substrate 30 and the support base 85 becomes small, and the temperature of the end portion becomes higher than that of the central portion. Therefore, when the thickness of the single crystal diamond layer 50 is 0.5 mm or more, at the end of growth, the growth of the end portion is larger than that of the central portion, and the end portion is raised from the central portion. Is observed.

As shown in FIG. 10, in the manufacturing method described in Patent Document 4, the single crystal diamond layer 50 is grown on the seed substrate 30 in which the groove 136 is formed by a laser. At this time, a bonding layer 60 made of polycrystalline diamond or non-diamond carbon is formed on the groove 136. Therefore, the active species of carbon is consumed for the growth of the single crystal diamond in the place where the groove 136 is not formed, and is consumed for the formation of the bonding layer 60 in the place where the groove 136 is formed. As a result, the shape when the growth fringes 219 observed on the cross section of the adjacent single crystal diamond layer 50 are continuous is the same as the growth fringes 119 shown in FIG. Then, linear growth stripes 219 are observed in the cross section of each single crystal diamond layer 50.

On the other hand, in the production method of the present embodiment, since the metal film 40 is present on the surface of the groove 36, the active species are deposited at the place where the metal film 40 is formed, as shown in FIGS. 11 and 12. Instead, it is returned upward. Due to the flow of active seeds returning upward without depositing on the metal film 40, a part of the flow of active seeds toward the main surface of the seed substrate 30 is inclined from the normal direction of the main surface.

Specifically, as shown in FIG. 11, the flow 71 of the active species returning from the metal film 40 located between the long sides of the plurality of rectangular regions 34 is the active species flowing toward the vicinity of the long sides of the region 34. The flow 72 is tilted towards the central portion of the region 34 in the short side direction. Therefore, the active species are likely to be deposited near the center in the short side direction in the rectangular region 34. As a result, the single crystal diamond epitaxially grown in the region 34 has a raised shape as it gets closer to the center thereof. The degree of this excitement is rarely seen in the early stages of growth, but gradually increases as the growth progresses. As a result, as shown in FIG. 8, in the cross section 18, the second growth fringe 19 observed on one end side of the second direction D2 becomes linear, and the second growth fringe 19 observed on the other end side of the second direction D2 becomes linear. The two growth fringes 19 have a convex shape from one end of the second direction D2 toward the other end.

Similarly, as shown in FIG. 12, the active species flow 73 returning from the metal film 40 located between the short sides of the plurality of rectangular regions 34 is the active species flow 74 toward the vicinity of the short sides of the region 34. Is tilted toward the central portion of the region 34 in the long side direction. Therefore, the active species are likely to be deposited near the center in the long side direction in the rectangular region 34. As a result, the single crystal diamond epitaxially grown in the region 34 has a raised shape as it gets closer to the center thereof. The degree of this excitement is rarely seen in the early stages of growth, but gradually increases as the growth progresses. As a result, as shown in FIG. 6, on the main surface 11, the first growth fringe 17 observed on one end side of the first direction D1 becomes linear and is observed on the other end side of the first direction D1. The first growth fringe 17 has a convex shape from one end to the other end in the first direction D1.

The gap between the end face of the seed substrate 30 and the support base 85 is set to be less than 0.5 mm. As described in Patent Document 5, by setting the gap between the end face of the seed substrate 30 and the support 85 to be less than 0.5 mm, the growth rate of the end portion of the seed substrate 30 is set to the growth rate of the central portion of the seed substrate. It can be slower than speed.

Returning to FIG. 8, the plane orientation of the main surface 11 of the single crystal diamond substrate 10 is appropriately selected according to the method of using the single crystal diamond substrate 10. When the single crystal diamond substrate 10 is used as a cutting tool, the (110) surface is often used as a rake surface. Therefore, the off angle of the main surface 11 with respect to the (110) surface is preferably 0 degrees or more and 20 degrees or less. This makes it easier to use the single crystal diamond substrate 10 as a cutting tool.

The side surface 13 of the main surface 11 intersecting with one end of the first direction D1 has a flat rectangular shape. The off angle of the side surface 13 with respect to the (001) plane is preferably 1 degree or more and 10 degrees or less. Further, the angle formed by the in-plane off direction projected on the side surface 13 with respect to the (001) surface of the side surface 13 and the long side of the side surface 13 is inferior formed by the long side of the side surface 13 and the diagonal line of the side surface 13. It is preferably less than or equal to the angle. The configuration is realized by the following in the first step and the second step described above. That is, in the first step, the seed substrate 30 having an off angle of the main surface 32 with respect to the (001) surface of 1 degree or more and 10 degrees or less is used. Further, in the second step, the angle formed by the in-plane off direction of the main surface 32 of the seed substrate 30 with respect to the (001) surface and the long side of the rectangular region 34 is formed by the long side of the region 34 and the diagonal line. Make it less than or equal to the inferior angle. As a result, as described above, the decrease in the growth rate is suppressed, and the single crystal diamond substrate 10 can be easily manufactured.

The single crystal diamond substrate 10 preferably contains a metal exhibiting ferromagnetism in at least a part of the side surface 13. In this configuration, a metal film 40 containing a metal exhibiting ferromagnetism is formed on the seed substrate 30 in the second step, and a part of the metal film 40 is on the single crystal diamond layer 50 side in the fifth step. It is realized by separating a plurality of single crystal diamond layers 50 so as to be included.

In the case of the manufacturing method shown in FIG. 1, a plurality of single crystal diamond layers 50 are separated by cleaving the seed substrate 30 along the groove 36. Therefore, a part of the seed substrate 30 is present on the side surface 13 of the single crystal diamond substrate 10. The metal film 40 formed on the seed substrate 30 erodes the seed substrate 30 even in the early stage of epitaxial growth of single crystal diamond. Therefore, the single crystal diamond substrate 10 contains a metal on the side surface 13. When the metal film 40 contains a metal exhibiting ferromagnetism (for example, at least one of Fe, Ni, and Co), the orientation of the single crystal diamond substrate 10 can be easily determined by bringing the magnets closer to each other. That is, in the single crystal diamond substrate 10, the portion formed at the early stage of growth and the portion formed at the final stage of growth can be discriminated.

<Application example of single crystal diamond substrate>
Next, an example of a cutting tool to which the single crystal diamond substrate 10 is applied will be described. FIG. 13 is a diagram showing an example of a cutting tool. FIG. 14 is a plan view showing the tip of the cutting tool. FIG. 15 is a cross-sectional view taken along the line XX shown in FIG.

As shown in FIG. 13, the cutting tool 8 includes a holder 7 and a single crystal diamond substrate 10 attached to the tip of the holder 7 and processed into a cutting edge shape. In the example shown in FIG. 13, the work material Z is cut by bringing the cutting tool 8 into contact with the rotating work material Z.

As shown in FIG. 14, the tip of the cutting edge made of the single crystal diamond substrate 10 is processed into a curved surface. Therefore, the curved surface of the tip of the cutting edge is aligned with the convex first growth fringe 17 observed on the other end side of the first direction D1. Thereby, the end portion of the rake face in contact with the work material Z can be made into a crystal grown under the same conditions and environment. As a result, it is possible to provide a cutting tool in which streaks are suppressed from being formed on the work material due to a slight difference in the crystal state. Further, it is difficult to apply a force for separating the first growth fringes 17 at the end of the rake face, and it is possible to suppress the chipping of the single crystal diamond substrate 10.

Further, as shown in FIG. 15, the bending of the curved surface from the rake face to the flank surface of the cutting edge is observed on the other end side of the second direction D2 in the cross section 18 of the single crystal diamond substrate 10. 2 Match the way the growth stripe 19 bends. Thereby, the cutting edge portion in contact with the work material Z from the rake face to the flank surface can be made into a crystal grown under the same conditions and environment. As a result, it is possible to prevent the work material from being streaked due to the slight difference in the crystal state. Further, it is difficult to apply a force for separating the second growth fringes 19 from the rake face to the flank surface, and the chipping of the single crystal diamond substrate 10 can be suppressed.

<Modification example of single crystal diamond substrate>
FIG. 16 is a perspective view showing another example of the single crystal diamond substrate 10. As shown in FIG. 16, the distance between the pair of main surfaces 11 and 12 becomes shorter from one end of the first direction D1 and the second direction D2 toward the other end. The single crystal diamond substrate 10 shown in FIG. 16 is manufactured by adjusting the epitaxial growth conditions so that the width of the single crystal diamond layer 50 gradually decreases as the growth progresses in the above manufacturing method. In the single crystal diamond substrate 10 shown in FIG. 16, the angle between the main surface 11 and the side surface 13 can be made smaller than 90 degrees (for example, 70 to 85 degrees).

In the above description, the single crystal diamond substrate 10 manufactured by forming the metal film 40 in a lattice pattern has been described. Manufactured by forming a linear metal film 40 along the long side of the rectangular region 34 and setting the thickness of the single crystal diamond layer 50 to 0.5 mm or more, which is longer than the short side length of the rectangular region 34. In the single crystal diamond substrate 10, the first growth fringes 17 and the second growth fringes 19 are as follows. The first growth fringe 17 observed on the main surface 11 has a shape similar to that of the growth fringe 119 shown in FIG. This is because the metal film 40 is formed only along the long side direction of the rectangular region 34. On the other hand, the second growth fringe 19 observed in the cross section 18 has the same shape as the second growth fringe 19 shown in FIG. That is, in the cross section 18, the second growth fringe 19 observed on one end side of the second direction D2 is linear, and the second growth fringe 19 observed on the other end side of the second direction D2 is the second direction. It is convex from one end of D2 to the other end. Further, since the thickness of the single crystal diamond layer 50 is 0.5 mm or more, the length from one end to the other end of the second direction D2 in the cross section 18 is 0.5 mm or more. The upper limit of the length from one end to the other end of the second direction D2 in the cross section 18 is not particularly limited.

As a result, by using the main surface 11 of the single crystal diamond substrate 10 as the rake face of the cutting edge, the bending of the curved surface from the rake face to the flank is observed on the other end side of the second direction D2 in the cross section 18. It can be matched to the bending of the convex second growth stripe 19. As a result, it is possible to provide a cutting tool in which the cutting edge portion that comes into contact with the work material from the rake face to the flank surface can be formed into crystals grown under the same conditions and environment, and streaks are suppressed in the work material. .. Further, the chipping of the single crystal diamond substrate 10 can be suppressed.

The single crystal can also be formed by forming the linear metal film 40 along the long side of the rectangular region 34 and setting the thickness of the single crystal diamond layer 50 to 0.5 mm or more, as in FIG. The surface of the diamond substrate 10 includes a flat rectangular side surface 13 including one end of the second direction D2 in cross section 18. Even in this case, the off angle of the side surface 13 with respect to the (001) plane is preferably 1 degree or more and 10 degrees or less. Further, the angle formed by the in-plane off direction projected on the side surface 13 with respect to the (001) surface of the side surface 13 and the long side of the side surface 13 is inferior formed by the long side of the side surface 13 and the diagonal line of the side surface 13. It is preferable that the angle is less than or equal to the angle. As a result, the decrease in the growth rate is suppressed, and the single crystal diamond substrate 10 can be easily manufactured.

Hereinafter, the present disclosure will be described in more detail with reference to examples, but the present invention is not limited thereto. Sample No. The single crystal diamond substrates 1 to 8 are examples, and the sample No. The single crystal diamond substrates 9 to 11 are comparative examples.

<Sample No. 1 single crystal diamond substrate>
A substrate A having a main surface having an off angle of 3 degrees with respect to the surface (100) and having a size of 6 mm × 6 mm × 0.5 mm was prepared as a seed substrate. Specifically, the main surface of the Ib type substrate produced by the high-pressure synthesis method was polished so that the surface roughness Ra was less than 50 nm, and carbon ions were injected into the main surface. The main surface of the Ib type substrate has an off angle of 3 degrees with respect to the (100) surface. A single crystal diamond was epitaxially grown on the main surface of the Ib type substrate by a chemical vapor deposition method, and the grown single crystal diamond was separated from the Ib type substrate by electrochemical etching to obtain a substrate A. Since the surface roughness Ra of the main surface of the Ib type substrate was less than 50 nm, the surface roughness Ra of the separation surface of the substrate A was also less than 50 nm.

Next, after the main surface of the seed substrate was polished and flattened, ^{carbon ions having a dose of 7 × 10 15} cm- ² were injected at 300 keV into the main surface.

Next, Ni was vapor-deposited on the main surface of the seed substrate to form a Ni film, and then the Ni film was patterned in a straight line with a width of 25 μm by a photolithography method. The thickness of the Ni film was 1 μm, and the distance between two adjacent lines (that is, the distance between the closest edges of the two lines) was 1.2 mm. The line direction was the <1-10> direction of the seed substrate.

Next, the seed substrate on which the linear Ni film was formed was placed in the chamber of the chemical vapor deposition apparatus. Then, hydrogen gas (100%) was introduced into the chamber at a flow rate of 800 sccm, and the pressure in the chamber was raised from 1.33 kPa to 13.3 kPa in a state where hydrogen plasma was generated using a microwave plasma device. Here, the unit of flow rate "sccm (Standard Cubic Centimeter per Minute)" indicates "mL / min" in the standard state (0 ° C., 101.3 kPa). In this environment, the temperature of the seed substrate was stabilized at 980 ° C. and then maintained in that state for 20 minutes.

Then, 800 sccm of hydrogen gas, 12 sccm of methane gas, and 1 sccm of nitrogen gas were introduced, and the temperature of the seed substrate was also adjusted to around 5 kW so that the temperature of the seed substrate was 980 ° C., and the single crystal diamond was epitaxially grown for 75 hours. As a result, a single crystal diamond complex having a seed substrate and a plurality of single crystal diamond layers having a thickness of 1.4 mm formed on the seed substrate was obtained.

Next, the single crystal diamond composite was electrochemically etched in pure water to separate the plurality of single crystal diamond layers from each other, and then the side surfaces of the separated single crystal diamond layers were polished to obtain the sample No. The single crystal diamond substrate of No. 1 was prepared.

<Sample No. 2 single crystal diamond substrate>
Sample No. except that the line width of the Ni film was 50 μm. Sample No. 1 under the same conditions as 1. 2 single crystal diamond substrates were prepared.

<Sample No. 3 single crystal diamond substrate>
Multiple single crystal diamond layers by not injecting carbon ions into the main surface of the seed substrate and by opening the seed substrate along a linearly formed Ni film instead of electrochemical etching. Except for the point where Sample No. 1 under the same conditions as 1. A single crystal diamond substrate of 3 was prepared.

<Sample No. Single crystal diamond substrate of 4>
A plurality of single crystal diamond layers were separated by not injecting carbon ions into the main surface of the seed substrate and by opening along a linearly formed Ni film instead of electrochemical etching. Except for the points, the sample No. Sample No. 2 under the same conditions as in 2. The single crystal diamond substrate of No. 4 was prepared.

<Sample No. 5 single crystal diamond substrate>
Except for the fact that the substrate B was prepared as a seed substrate instead of the substrate A and that the polishing of the main surface of the seed substrate after carbon ion implantation was omitted, the sample No. Sample No. 1 under the same conditions as 1. A single crystal diamond substrate of 5 was prepared.

The substrate B has a main surface having an off angle of 3 degrees with respect to the (100) surface, and has a size of 6 mm × 6 mm × 0.1 mm. The substrate B is manufactured by the same method as the substrate A, only the size is different from that of the substrate A. Further, since the thickness of the substrate B is 0.1 mm, which is thinner than that of the substrate A, the polishing process for the substrate B is omitted.

<Sample No. 6 single crystal diamond substrate>
Sample No. except that the line width of the Ni film was 50 μm. Sample No. 5 under the same conditions as 5. 6 single crystal diamond substrates were prepared.

<Sample No. 7 single crystal diamond substrate>
A plurality of single crystal diamond layers were separated by not implanting carbon ions into the main surface of the seed substrate and by cleaving along a linearly formed Ni film instead of electrochemical etching. Except for the points, the sample No. Sample No. 5 under the same conditions as 5. 7 single crystal diamond substrates were prepared.

<Sample No. 8 single crystal diamond substrate>
A plurality of single crystal diamond layers were separated by not implanting carbon ions into the main surface of the seed substrate and by cleaving along a linearly formed Ni film instead of electrochemical etching. Except for the points, the sample No. Sample No. 6 under the same conditions as No. 6. 8 single crystal diamond substrates were prepared.

<Sample No. 9 single crystal diamond substrate>
Sample No. In the same manner as in 1, the substrate A is used as a seed substrate, and after polishing and flattening the main surface of the seed substrate, carbon ions having a dose of ^{7 × 10 15} cm- ^{2 are injected at 300 keV into the main surface.} did.

Next, grooves having a width of 30 μm and a depth of 30 μm were formed at intervals of 1.2 mm on the main surface of the seed substrate with a laser.

Then, the grooved seed substrate was placed in the chamber of the chemical vapor deposition apparatus, and the single crystal diamond was epitaxially grown on the seed substrate. The epitaxial growth conditions were as follows so that a bonding layer was formed on the groove instead of single crystal diamond. That is, the methane gas flow rate was 8 sccm, the hydrogen gas flow rate was 900 sccm, the nitrogen gas flow rate was 0.7 sccm, and the microwave power was 6 kW. Then, the methane gas flow rate was 10 sccm, the hydrogen gas flow rate was 800 sccm, the nitrogen gas flow rate was 1 sccm, and the microwave power was 6 kW, and the mixture was grown for 70 hours. As a result, single crystal diamond was epitaxially grown on the main surface of the seed substrate to obtain a plurality of single crystal diamond layers having a thickness of 1.6 mm. At this time, active species were also deposited on the groove, and the groove was filled. Therefore, the portion where the groove was formed was irradiated with a laser to separate the single crystal diamond layer along the portion where the groove was formed.

Next, the seed substrate on which the single crystal diamond layer was formed was electrochemically etched in pure water to separate the plurality of single crystal diamond layers, whereby the sample No. The single crystal diamond substrate of No. 1 was prepared.

<Sample No. 10 single crystal diamond substrates>
Except for the fact that grooves having a width of 100 μm and a depth of 220 μm were formed at intervals of 1.2 mm on the main surface of the seed substrate, the sample No. Sample No. 9 under the same conditions as No. 9. Ten single crystal diamond substrates were prepared. However, the width of the groove is the sample No. Since the size is larger than that of 9, the single crystal diamond layers bonded to each other through the bonding layer grew without filling the grooves with the single crystal diamond. The bonding layer is not single crystal diamond. Therefore, the single crystal diamond layer could be separated without using a laser by sublimating a part of the bonding layer by heat treatment in the atmosphere and weakening a part of the bond.

<Sample No. 11 single crystal diamond substrates>
Sample No. In the same manner as in No. 5, the substrate B was used as a seed substrate, and ^{a dose of 7 × 10 15} cm- ² carbon was ion-implanted at 300 keV into the main surface of the seed substrate.

Next, grooves having a width of 30 μm and a depth of 60 μm were formed at intervals of 1.2 mm on the main surface of the seed substrate with a laser. After that, the seed substrate was cracked when the seed substrate in which the groove was formed was conveyed. Therefore, it was not possible to epitaxially grow single crystal diamond on the seed substrate.

<Evaluation>
Sample No. The main surface of the single crystal diamond substrates 1 to 10 corresponds to the side surface along the linear Ni film or groove in the epitaxially grown single crystal diamond layer. Since the side surface of the single crystal diamond layer was substantially (110), the sample No. was obtained by polishing the side surface. The main surface of the single crystal diamond substrates 1 to 10 could be the (110) surface. That is, it was possible to obtain a single crystal diamond substrate having a plane orientation different from the plane orientation of the main surface of the seed substrate.

As shown in Table 1, sample No. With the exception of 12, single crystal diamond substrates of similar size could be obtained. However, the sample No. Regarding the single crystal diamond substrate of No. 9, when the single crystal diamond layer was grown, the single crystal diamond also grew on the groove. Therefore, it takes time and effort to separate the single crystal diamond layer bonded by irradiating the portion where the groove is formed with a laser. Further, in the single crystal diamond substrate of Sample No. 10, a bonding layer was formed on the groove. Since the bonding layer is not a single crystal diamond, the sample No. Although it takes less time to separate than No. 9, it requires time and effort to remove the bonding layer.

On the other hand, sample No. In the manufacturing process of the single crystal diamond substrates 1 to 8, the single crystal diamond or the bonding layer was not formed on the groove as in the manufacturing process of the single crystal diamond substrates of Samples Nos. 9 and 10. In particular, sample No. In the process of manufacturing the single crystal diamond substrates of 1, 3, 5, and 7, although the width of the Ni film was narrow, the single crystal diamond and the bonding layer did not grow on the grooves. Therefore, the sample No. The time and effort required to separate the single crystal diamond layer by laser irradiation as in No. 9 and the sample No. The single crystal diamond substrate could be easily produced without the trouble of removing the bonding layer as in No. 10. As described above, it was confirmed that the productivity is increased according to the production method described in the above-described embodiment.

Sample No. In the manufacturing process of the single crystal diamond substrates 5 to 8, the substrate B having a thickness of 0.1 mm was used as the seed substrate. Unlike the manufacturing process of the single crystal diamond substrate of No. 11, the seed substrate was not cracked, and the single crystal diamond substrate could be produced. This is because the single crystal diamond layer can be epitaxially grown without transporting the seed substrate after the groove is formed by eroding the Ni film on the seed substrate. As described above, it was confirmed that the seed substrate can be easily handled according to the manufacturing method described in the above embodiment.

Next, sample No. The single crystal diamond substrates 1 to 10 were machined into the shape of a cutting tool, and a cutting test was conducted as a cutting tool. The end of the single crystal diamond substrate on the end-of-growth side was processed so as to be the cutting edge.

Table 2 below shows the presence or absence of chipping during processing of the single crystal diamond substrate and chipping of the single crystal diamond substrate after the 1-hour cutting test.

As shown in Table 2, the sample No. No chipping was observed in the single crystal diamond substrates 1 to 8 even after the 1-hour cutting test.

Sample No. on the plane parallel to the growth direction. The mapping image of the photoluminescence (PL) intensity in the cross section of the single crystal diamond substrate of 1 to 10 was confirmed. Sample No. In the cross sections of the single crystal diamond substrates 1 to 10, growth fringes arranged along the second direction D2, which is the growth direction in the cross section, were observed. Sample No. In the cross sections of the single crystal diamond substrates 1 to 8, linear growth fringes are observed on one end side of the second direction D2, and on the other end side of the second direction D2, from one end to the other end of the second direction D2. Convex growth fringes facing the direction were observed. Due to the convex growth fringes, the portion in contact with the work material becomes a crystal grown under the same conditions and environment, and it becomes difficult to apply a force for separating the growth fringes. It is presumed that the chipping of the single crystal diamond substrates 1 to 10 was suppressed. On the other hand, sample No. In the cross sections of the single crystal diamond substrates 9 and 10, linear growth fringes were observed on both one end side and the other end side of the second direction D2. Due to the linear growth fringes, the sample No. In the single crystal diamond substrates 1 to 8, the convex growth fringes in the cross section make it easy to apply a force for separating the growth fringes, and the sample No. It is presumed that the 9 and 10 single crystal diamond substrates were chipped.

<Appendix>
The above description includes the features described below.

<Appendix 1>
The method for producing a single crystal diamond is a step of linearly forming a metal film in which carbon can be dissolved on the main surface of the seed substrate of the single crystal diamond, and generating hydrogen plasma around the seed substrate. , The step of eroding the seed substrate with the metal film to form a groove on the main surface, and after forming the groove, the chemical gas is placed on the region where the metal film is not formed on the main surface. It includes a step of forming a single crystal diamond layer by a phase growth method.

<Appendix 2>
The method for producing a single crystal diamond is a step of linearly forming a metal film in which carbon can be dissolved on the main surface of the seed substrate of the single crystal diamond, and the seed substrate is installed in a chamber to form the seed substrate. By generating hydrogen plasma around the surface, the seed substrate is eroded by the metal film to form a groove on the main surface, and a raw material gas is introduced into the chamber after the groove is formed. A step of forming a single crystal diamond layer by a chemical vapor phase growth method is provided on the region where the metal film is not formed on the main surface.

<Appendix 3>
The method for producing a single crystal diamond is a step of linearly forming a metal film in which carbon can be dissolved on the main surface of the seed substrate of the single crystal diamond, and the seed substrate is placed in a chamber to form a hydrogen atom and a hydrogen atom. A step of eroding the seed substrate with the metal film by heat-treating the seed substrate in a gas of a molecule containing at least one of oxygen atoms to form a groove on the main surface, and after forming the groove. A step of introducing a raw material gas into the chamber and forming a single crystal diamond layer by a chemical vapor phase growth method on a region where the metal film is not formed on the main surface is provided.

Although the embodiments and examples of the present invention have been described above, it is planned from the beginning that the configurations of the above-described embodiments and examples may be appropriately combined or modified in various ways.

The embodiments and examples disclosed this time should be considered as exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the embodiments and examples described above, and is intended to include meaning equivalent to the scope of claims and all modifications within the scope.

7 Holder 8 Cutting Tool 10 Single Crystal Diamond Substrate 11, 12, 32 Main Surface 13, 14, 15, 16 Side 17 First Growth Stripe 18 Cross Section 19 Second Growth Stripe 20 Single Crystal Diamond Composite 30 Type Substrate 34 Region 36, 136 Groove 38 Carbon ion injection layer 40 Metal film 50 Single crystal diamond layer 60 Bonding layer 71, 72, 73, 74 Active species flow 80 Microwave plasma device 81 Chamber 82 Microwave power supply 83 Waveguide tube 84 Microwave introduction window 85 Support base 86 Gas supply pipe 87 Gas discharge pipe 88 Plasma 119,219 Growth fringes D1 First direction D2 Second direction S1 Target surface S2 Reference surface Z Work material a1 Off direction a11 In-plane off direction a2, n Normal direction.

Claims (12)

A process of linearly forming a metal film in which carbon can be dissolved on the main surface of a single crystal diamond seed substrate, and
A step of heat-treating the seed substrate in a gas of a molecule containing at least one of a hydrogen atom and an oxygen atom to erode the seed substrate with the metal film to form a groove on the main surface.
After forming the trenches, on the region where the metal film is not formed in the main surface, Bei example and forming a single crystal diamond layer by chemical vapor deposition,
In the step of forming the metal film linearly, the metal film is formed in a linear or lattice shape so that the region becomes rectangular.
The off angle of the main surface with respect to the (001) surface is 1 degree or more and 10 degrees or less.
The angle formed by the in-plane off direction obtained by projecting the off direction of the main surface with respect to the (001) plane onto the main surface and the long side of the region is equal to or less than the inferior angle formed by the long side and the diagonal line of the region. There is a method for producing single crystal diamond. In the step of forming the metal film linearly, the metal film is formed in a linear or lattice shape so that the region becomes rectangular.
The method for producing a single crystal diamond according to claim 1, wherein the thickness of the single crystal diamond layer is longer than the short side length of the region. The method for producing a single crystal diamond according to claim 1 or 2 , wherein the metal film contains a metal exhibiting ferromagnetism. In the step of forming the single crystal diamond layer, a plurality of single crystal diamond layers are formed on the main surface.
The method for producing single crystal diamond according to any one of claims 1 to 3 , further comprising a step of separating the plurality of single crystal diamond layers from each other. A single crystal diamond seed substrate with grooves formed on the main surface,
A single crystal diamond layer formed on the region excluding the groove on the main surface is provided.
On the surface of the grooves in the seed substrate, seen containing a metal film in which the carbon is dissolved,
The metal film is linear or grid-like so that the region is rectangular.
The off angle of the main surface with respect to the (001) surface is 1 degree or more and 10 degrees or less.
The angle formed by the in-plane off direction obtained by projecting the off direction of the main surface with respect to the (001) plane onto the main surface and the long side of the region is equal to or less than the inferior angle formed by the long side and the diagonal line of the region. There is a single crystal diamond complex. It is a single crystal diamond substrate
The surface of the single crystal diamond substrate includes a pair of main surfaces.
On at least one of the pair of main surfaces, a first growth fringe showing a change in at least one of the defect amount and the impurity concentration was observed.
The first growth fringes are arranged along a first direction in at least one of the main planes.
On at least one of the main surfaces, the first growth fringe observed on one end side in the first direction is linear, and the first growth fringe observed on the other end side in the first direction is said. It is a convex shape from the one end in the first direction toward the other end.
Length from said one end of said first direction in said at least one main face to the other end Ri der least 0.5 mm,
The surface of the single crystal diamond substrate includes a side surface of the at least one main surface that intersects the one end in the first direction.
The side surface has a flat rectangular shape and has a flat rectangular shape.
The off-angle of the side surface with respect to the (001) surface is 1 degree or more and 10 degrees or less.
The angle formed by the in-plane off direction projected on the side surface with respect to the (001) surface of the side surface and the long side of the side surface is equal to or less than the inferior angle formed by the diagonal line of the long side and the side surface. Single crystal diamond substrate. Before SL is parallel to the first direction, and the cross section when taken along the single crystal diamond substrate in a plane perpendicular to said pair of main surfaces, a second growth striations indicating at least one of a change in the amount of defects and impurities concentration Is observed,
The second growth fringes are arranged along a second direction in the cross section.
One end of the cross section in the second direction is a line of intersection between the cross section and the side surface.
In the cross section, the second growth fringe observed on the one end side in the second direction is linear, and the second growth fringe observed on the other end side in the second direction is the second direction. The single crystal diamond substrate according to claim 6 , which is convex from one end of the above to the other end. The single crystal diamond substrate according to claim 6 or 7 , wherein the distance between the pair of main surfaces becomes shorter from the one end to the other end in the first direction. It is a single crystal diamond substrate
The surface of the single crystal diamond substrate includes a pair of main surfaces.
On at least one of the pair of main surfaces, a first growth fringe showing a change in at least one of the defect amount and the impurity concentration was observed.
The first growth fringes are arranged along a first direction in at least one of the main planes.
A second growth fringe showing a change in at least one of the defect amount and the impurity concentration is formed on the cross section when the single crystal diamond substrate is cut on a plane parallel to the first direction and perpendicular to the pair of main planes. Observed,
The second growth fringes are arranged along a second direction in the cross section.
In the cross section, the second growth fringe observed on one end side of the second direction is linear, and the second growth fringe observed on the other end side of the second direction is in the second direction. It is convex from the one end to the other end.
Length from the one end of the second direction in the cross section to the other end Ri der least 0.5 mm,
The surface of the single crystal diamond substrate comprises a flat rectangular side surface including the one end in the second direction in the cross section.
The off-angle of the side surface with respect to the (001) surface is 1 degree or more and 10 degrees or less.
The angle formed by the in-plane off direction projected on the side surface with respect to the (001) surface of the side surface and the long side of the side surface is equal to or less than the inferior angle formed by the diagonal line of the long side and the side surface. , Single crystal diamond substrate. The single crystal diamond substrate according to claim 9 , wherein the distance between the pair of main surfaces becomes shorter from the one end to the other end in the second direction. The single crystal diamond substrate according to claim 9 , wherein at least a part of the side surface contains a metal exhibiting ferromagnetism. The single crystal diamond substrate according to any one of claims 9 to 11 , wherein the off-angle of at least one main surface with respect to the (110) surface is 0 degrees or more and 20 degrees or less.

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