JP6228404B2 - Diamond composite, diamond bonded body, single crystal diamond and tool including the same - Google Patents

Description

  The present invention relates to a diamond composite, a diamond bonded body, a single crystal diamond, and a tool including the same.

  Single crystal diamond has excellent performance such as high hardness, high thermal conductivity, and high light transmission, so various products such as cutting tools, grinding tools, anti-wear tools, optical components, semiconductors, electronic components, etc. (Hereinafter also referred to as “diamond products”). Single-crystal diamonds used in such diamond products include natural diamonds and synthetic diamonds. However, natural diamonds are widely used because of their large variations in quality and unstable supply. It has been.

  As one of the methods for producing the synthetic diamond described above, a high pressure high temperature method (HPHT) is known. Single crystal diamond produced by this method has small variations in quality and stable supply, but has a problem that the cost of production equipment used is high.

  As another synthetic diamond manufacturing method, there is a chemical vapor deposition (CVD) method such as a hot filament CVD (Chemical Vapor Deposition) method, a microwave excitation plasma CVD method, and a DC plasma CVD method. In the CVD method, single crystal diamond can be obtained by growing single crystal diamond (epitaxial growth layer) on the surface of the substrate and then separating the substrate and single crystal diamond.

  For example, in Japanese Patent Application Laid-Open No. 2006-315942 (Patent Document 1), a single crystal diamond (epitaxial growth layer) is manufactured by a microwave-excited plasma CVD method on a seed substrate made of a single crystal diamond manufactured by a high temperature and high pressure synthesis method. A method is disclosed. Single crystal diamond obtained by such a CVD method has a small variation in quality, a stable supply amount, and the cost of manufacturing equipment is lower than that of the above high-temperature and high-pressure synthesis method.

JP 2006-315942 A

  However, single crystal diamond obtained by the CVD method is an epitaxially grown layer, and stress is likely to accumulate between the epitaxially grown layer and the substrate due to its manufacturing method. For this reason, the residual stress of the single crystal diamond increases, and as a result, defects such as distortion, cracks and cracks may occur in the single crystal diamond. Single crystal diamonds with defects are not suitable for use in diamond products. Further, even if there is no defect in the single crystal diamond immediately after production, since it has a large residual stress, there is a concern that a defect may occur during its processing, use after processing, and the like.

  This invention is made | formed in view of the said subject, and it aims at providing the diamond composite_body | complex suitable for a diamond product, a diamond joined body, a single crystal diamond, and a tool provided with this.

  When manufacturing single-crystal diamond on a substrate by the CVD method, the present inventors set the substrate to be used in a specific mode different from usual, or various conditions in the CVD method with specific conditions different from normal. In this case, it has been found that a diamond composite in which a carbonaceous layer containing non-diamond carbon is formed on the surface of a single crystal diamond formed on a substrate is formed. As a result of intensive studies on this diamond composite, it was found that the single crystal diamond obtained therefrom had a lower probability of occurrence of defects than the single crystal diamond obtained by the conventional CVD method, and the present invention was completed. It is a thing.

  That is, the present invention includes a substrate made of a diamond seed crystal, a single crystal diamond formed on the main surface of the substrate, and a carbonaceous layer covering the side surface of the single crystal diamond, and the carbonaceous layer is a non-diamond. It is a diamond composite containing carbon.

  Moreover, this invention is a diamond joined body obtained by removing a board | substrate or a carbonaceous layer from the said diamond composite_body | complex.

  Further, the present invention is a single crystal diamond obtained by removing a substrate and a carbonaceous layer from the diamond composite.

  Moreover, this invention is a tool provided with the said single crystal diamond.

  ADVANTAGE OF THE INVENTION According to this invention, the diamond composite suitable for a diamond product, a diamond joined body, a single crystal diamond, and a tool provided with this can be provided.

It is a schematic sectional drawing of the diamond composite of this embodiment. It is a schematic perspective view of the board | substrate of this embodiment. 3A to 3D are views for explaining the off-angle of the side surface of the substrate, FIG. 3A is a schematic side view of an example of the substrate, and FIG. FIG. 3C is a schematic side view of another example of the substrate, FIG. 3C is a schematic top view of still another example of the substrate, and FIG. 3D is a schematic diagram of yet another example of the substrate. FIG. It is a schematic side view which shows the other example of a board | substrate. It is a schematic sectional drawing of the diamond joined object of this embodiment. It is a schematic sectional drawing of the diamond joined object of this embodiment. It is a schematic sectional drawing of the single crystal diamond of this embodiment. It is a schematic sectional drawing of the diamond cutting tool which is an example of the tool of this embodiment.

[Description of Embodiment of Present Invention]
First, embodiments of the present invention will be listed and described.

  (1) A first aspect of the present invention includes a substrate comprising a diamond seed crystal, a single crystal diamond formed on a main surface of the substrate, and a carbonaceous layer covering the side surface of the single crystal diamond, The material layer is a diamond composite containing non-diamond carbon.

  Since the single crystal diamond separated from the diamond composite of the present invention has a small residual stress, the occurrence of defects such as strain, cracks and cracks is suppressed. Moreover, when this is utilized for a diamond product, generation | occurrence | production of the malfunction in a diamond product is suppressed. Therefore, according to the diamond composite of the present invention, single crystal diamond suitable for diamond products can be provided.

  (2) In the above diamond composite, preferably 1% by volume or more of the carbonaceous layer is non-diamond carbon. As a result, the single crystal diamond separated from the diamond composite has a smaller residual stress, thereby providing a single crystal diamond more suitable for a diamond product.

  (3) In the diamond composite, the main surface of the substrate has an off angle with respect to the (001) plane of 0 ° to 7 °, and the side surface of the substrate in contact with the main surface has an off angle with respect to the (100) surface. A first side surface having an angle greater than 8 ° and smaller than 37 °, a second side surface having an off angle with respect to the (-100) plane of greater than 8 ° and smaller than 37 °, and an off angle with respect to the (0-10) surface greater than 8 °. It is preferable to include a third side surface smaller than 37 ° and a fourth side surface whose off angle with respect to the (010) plane is larger than 8 ° and smaller than 37 °. Thereby, the single crystal diamond suitable for a diamond product can be provided further.

  (4) In the above diamond composite, the single crystal diamond can have a thickness of 0.5 mm or more. In the diamond composite, even when the thickness of the single crystal diamond is 0.5 mm or more, the occurrence of defects is sufficiently suppressed.

  (5) Moreover, the 2nd aspect of this invention is a diamond joined body obtained by removing a board | substrate or a carbonaceous layer from the said diamond composite_body | complex. Since the single crystal diamond separated from the diamond joined body of the present invention has a small residual stress, occurrence of defects in the diamond product is suppressed when used in a diamond product. Therefore, according to the diamond joined body of the present invention, it is possible to provide single crystal diamond suitable for diamond products.

  (6) A third aspect of the present invention is a single crystal diamond obtained by removing a substrate and a carbonaceous layer from the diamond composite. Since the single crystal diamond of the present invention has a small residual stress, when used in a diamond product, occurrence of defects in the diamond product is suppressed. Therefore, the single crystal diamond of the present invention is suitable for a diamond product.

  (7) A fourth aspect of the present invention is a tool comprising the above single crystal diamond. According to the tool of the present invention, since the single crystal diamond having a small residual stress is provided, the occurrence of defects in the single crystal diamond is suppressed. Therefore, it can have high performance as a tool.

[Details of the embodiment of the present invention]
Hereinafter, the diamond composite according to the present invention, the diamond bonded body, the single crystal diamond, and the tool including the same will be described in more detail. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated. Further, in this specification, individual directions are indicated by [], generic directions including crystal geometrically equivalent directions are indicated by <>, individual plane orientations are indicated by (), and crystal geometry A generic plane orientation including a plane equivalent plane is indicated by {}. As for the negative index, in crystal geometry, it is common to express “−” (bar) on the number representing the index, but in this specification, before the number representing the index. Represented with a negative sign (-).

<Diamond composite>
FIG. 1 is a schematic cross-sectional view of the diamond composite of this embodiment. Referring to FIG. 1, diamond composite 10 includes a substrate 1 made of a diamond seed crystal, single crystal diamond 2 formed on main surface 1 a of substrate 1, and a carbonaceous layer covering the surface of single crystal diamond 2. 3 and the carbonaceous layer 3 includes non-diamond carbon.

  The substrate 1 is diamond having a cubic single crystal structure. In the manufacturing method of the diamond composite 10, since the substrate 1 has high crystallinity, the single crystal diamond 2 can also have high crystallinity. Therefore, the substrate 1 preferably has high crystallinity. Since the single crystal diamond produced by the above-described high temperature and high pressure method has a homogeneous crystal structure and high crystallinity, the substrate 1 is preferably a single crystal diamond produced by the high temperature and high pressure method. Moreover, what processed the single crystal diamond obtained from the diamond composite_body | complex of this invention may be used. Usually, the thickness of the substrate 1 is about 0.2 mm to 2.0 mm, and the length of one side is 3.0 mm or more. From the viewpoint of increasing the cross-sectional area in the growth direction of the single crystal diamond 2 to be manufactured, it is preferable that the length of one side is large, but practically, the length of one side of one substrate is 3 to 12 mm. The length of one side of the bonded substrate obtained by combining a plurality of substrates is about 8 to 40 mm. Larger substrates or bonded substrates are difficult to obtain at this time.

  The single crystal diamond 2 is a diamond having a cubic single crystal structure, and is located on the main surface 1 a of the substrate 1. Specifically, the single crystal diamond 2 is an epitaxial growth layer formed by a CVD method, and the growth direction is an upward direction in the figure. The upper surface 2a of the single crystal diamond 2 inherits the plane orientation of the main surface 1a of the substrate 1, and the side surface 2b of the single crystal diamond 2 is a surface continuous with the side surfaces 1b to 1e (see FIG. 2) of the substrate 1. The surface orientations of the side surfaces 1b to 1e are taken over. Needless to say, the single crystal diamond 2 does not contain the following non-diamond carbon.

The carbonaceous layer 3 is a layer containing non-diamond carbon, and covers the side surface 2 b of the single crystal diamond 2. Non-diamond carbon means carbon that does not constitute a cubic single crystal structure. Such non-diamond carbon, and the like amorphous carbon containing graphite, a sp ² hybrid orbital and sp ³ hybrid orbital having sp ² hybrid orbital. The presence or absence of graphite in the carbonaceous layer 3 is, for example, X-ray diffraction, Raman spectroscopy, electron energy-loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS). It can be confirmed by cathodoluminescence (CL).

  In addition, the diamond having a cubic single crystal structure has high transparency, whereas the transparency of graphite is low. Therefore, depending on the graphite content, the presence or absence can be confirmed visually. The region other than non-diamond carbon in the carbonaceous layer 3 has a structure other than a single crystal simple substance, and can be composed of, for example, polycrystalline diamond. The thickness of the carbonaceous layer 3 is 10 μm or more, the thickness near the main surface 2a is thicker, and the thickness near the bottom surface opposite to the main surface 2a is thinner. Although the carbonaceous layer 3 basically covers the side surface 2b, a part of the side surface 2b may be exposed as a part thereof is lost due to handling of the diamond composite or the like.

  Regarding the diamond composite of the present embodiment, it is not clear why the occurrence of defects such as strain, cracks and cracks is suppressed in the single crystal diamond obtained from this, but the present invention is based on the results of various studies. They speculate as follows.

  That is, normally, when single crystal diamond is grown on the substrate by the CVD method, the single crystal diamond is formed not only on the main surface of the substrate but also on the side surface of the substrate. In other words, the single crystal diamond is fixed on the main surface and side surfaces of the substrate. This is because single crystal diamond grows from the main surface of the substrate, and single crystal diamond also grows from the side surface in contact with the main surface of the substrate, and these are bonded above the main surface of the substrate. Conceivable. Such single crystal diamond has a large residual stress due to its growth process and shape.

  On the other hand, in the diamond composite of the present invention, single crystal diamond is formed on the main surface of the substrate, and a carbonaceous layer is formed on the side surface of the single crystal diamond. In other words, single crystal diamond is fixed on the main surface of the substrate, and a carbonaceous layer is fixed on the side surface of the substrate. This is because single crystal diamond grows from the main surface of the substrate, and a carbonaceous layer grows from the side surface in contact with the main surface of the substrate, and these are bonded above the main surface of the substrate. It is done. In the diamond composite having such a configuration, the residual stress of the single crystal diamond is dispersed or reduced by the carbonaceous layer, and as a result, occurrence of defects is suppressed.

  Returning to FIG. 1, in the diamond composite 10, preferably 1% by volume or more of the carbonaceous layer is non-diamond carbon, more preferably 8% by volume or more, and further preferably 20% by volume or more is non-diamond carbon. . In the present specification, “volume%” is a value in a standard state of each single gas. In this case, the occurrence of defects in the single crystal diamond 2 is further suppressed. The reason for this is not clear, but it is considered that the residual stress of the single crystal diamond is more effectively dispersed or reduced by the carbonaceous layer 3 having a more brittle structure. More preferably, the carbonaceous layer 3 is made of non-diamond carbon.

  Further, the bonding force between the carbonaceous layer 3 and the single crystal diamond 2 is weak and can be easily separated. However, as the proportion of non-diamond carbon in the carbonaceous layer 3 increases, the bonding force further decreases. . Therefore, in the diamond composite 10, when 1% by volume or more, more preferably 8% by volume or more, and further preferably 20% by volume or more of the carbonaceous layer 3 is non-diamond carbon, the carbonaceous layer from the diamond composite 10 3 is even easier to separate. Further, regarding the diamond composite body 10 having such a carbonaceous layer 3, it is further easier to visually confirm the presence of the carbonaceous layer 3 and the boundary between the carbonaceous layer 3 and the single crystal diamond 2, The separation of the single crystal diamond 2 is further facilitated.

  Further, in the diamond composite 10, the main surface 1 a of the substrate 1 is preferably a (001) plane so that the single crystal diamond 2 can be efficiently formed with a large thickness (vertical direction in the drawing). In order to further improve the homogeneity of the crystal of the single crystal diamond 2, the main surface of the substrate 1 preferably has an off angle of 0 ° or more and 7 ° or less with respect to the (001) plane, and 1.5 ° or more and 6 ° or less. More preferably, it is not more than 0 °.

Moreover, since the shape of the main surface 1a affects the single crystal diamond 2, in order to further improve the homogeneity of the single crystal diamond 2, the main surface 1a is preferably smoothed and cleaned. Therefore, laser polishing, plasma etching, reactive ion etching (RIE: Reactive Ion Etching), mechanical polishing using a metal bond polishing machine in which diamond abrasive grains are embedded, a polishing machine using cast iron, etc. are applied to the main surface 1a. It is preferable that various processes such as chemical mechanical polishing (CMP) using an oxide (Al ₂ O ₃ , SiO _2, etc.) polishing machine are performed. For example, the main surface 1a may be subjected to plasma etching after mechanical polishing, or may be subjected to chemical mechanical polishing after laser cutting.

  Further, referring to FIG. 2, each of the side surfaces 1 b to 1 e in contact with the main surface 1 a of the substrate 1 is preferably the following surface. That is, the side surface 1b as the first side surface is preferably a surface having an off angle of greater than 8 ° and smaller than 37 ° with respect to the (100) plane. The side surface 1c as the second side surface is preferably a surface having an off angle greater than 8 ° and smaller than 37 ° with respect to the (−100) plane. The side surface 1d as the third side surface is preferably a surface having an off angle greater than 8 ° and smaller than 37 ° with respect to the (0-10) plane. The side surface 1e as the fourth side surface is preferably a surface having an off angle greater than 8 ° and smaller than 37 ° with respect to the (010) plane. The side surface 1b and the side surface 1c are surfaces facing each other, and the side surface 1d and the side surface 1e are surfaces facing each other.

  In this case, the present inventors have confirmed that the diamond composite 10 including the single crystal diamond 2 with few defects can be manufactured particularly efficiently. The reason for this is not clear, but it is considered that the growth of non-diamond carbon is particularly dominant with respect to the growth of the epitaxial layer from the side surfaces 1b to 1e of the substrate 1 at this angle. Each of the above-mentioned off angles is more preferably 10 ° or more and 30 ° or less, and further preferably 13 ° or more and 20 ° or less. In addition, although the magnitude | size (absolute value) of the off angle of each side surface 1b-1e may be the same or different, from a viewpoint of the ease of manufacture of the board | substrate 1, it is preferable that the angle with respect to the main surface 1a is symmetrical. .

  That is, when the main surface 1a is a (001) just surface, it is preferable that the magnitude | sizes (absolute value) of all the off angles of the four side surfaces 1b-1e are the same. On the other hand, when the main surface 1a is not a (001) plane just surface but a surface having an off-angle from the (001) plane, if the angles of the side surfaces 1b to 1e with respect to the main surface 1a are the same, the main surface 1a Due to the above-mentioned off angle, the off-angles (absolute values) of the side surfaces 1b to 1e are displaced. For this reason, when the main surface 1a is a surface having an off-angle from the (001) surface, making the off-angle sizes (absolute values) of the side surfaces 1b to 1e the same reduces the manufacturability. Accordingly, in this case, the off-angles of the side surfaces 1b to 1e are preferably different.

  Here, in general, the off-angle is not an angle based on the normal line of each surface, but an inclination based on the normal line of a low index crystal plane closer to each surface, and the surface orientation of each surface is It is determined by the off angle and the off angle direction. Further, in this specification, when the off-angle of each surface is expressed by the inclination angle in the vertical direction from the main surface (100) surface and the inclination angle in the horizontal direction from the main surface (100) surface. Needs to synthesize vectors in the respective tilt directions and convert them to off-angles. In order to make this easy to understand, the off angle with respect to the (100) plane of the side surface 1b as the first side surface will be specifically described with reference to FIGS. In addition, since it becomes the description similar to description of the side surface 1b also about the off angle of the side surfaces 1c-1e, the description is not repeated.

  FIG. 3A is a schematic side view of an example of the substrate. The main surface 1a of the substrate 1 is the (001) plane, and the arrow in the drawing parallel to the paper surface indicates the [001] direction. FIG. 3B is a schematic side view of another example of the substrate. The main surface 1a of the substrate 1 is the (001) plane, and the arrow in the drawing parallel to the paper surface indicates the [001] direction. . FIG. 3C is a schematic top view of still another example of the substrate. The main surface 1a of the substrate 1 is the (001) plane, and the arrow in the drawing indicates the [010] direction. FIG. 3D is a schematic top view of still another example of the substrate. The main surface 1a of the substrate 1 is the (001) plane, and the arrow in the drawing indicates the [010] direction. 3 (C) and 3 (D), the direction that penetrates the paper so as to be orthogonal is the [001] direction.

As shown in FIG. 3A, the side surface 1b is a surface having an off angle α1 in the <001> direction with respect to the (100) plane that is greater than 8 ° and smaller than 37 ° (8 ° <α1 <37 °). As shown in FIG. 3B, even if the off angle α2 in the <00-1> direction with respect to the (100) plane is larger than 8 ° and smaller than 37 ° (8 ° < α2 <37 °), Good. Further, as shown in FIG. 3C, the side surface 1b has an off angle β1 in the <0-10> direction with respect to the (100) plane that is larger than 8 ° and smaller than 37 ° (8 ° < β1 <37 °). As shown in FIG. 3D, the off angle β2 in the <010> direction with respect to the (100) plane is greater than 8 ° and smaller than 37 ° (8 ° < β2 <37 °). May be.

  3A and 3B, an example in which the side surface 1b is turned off with respect to the vertical direction of the main surface 1a (hereinafter, also referred to as “main surface vertical direction”) is illustrated in FIG. ) And (D), the side surface 1b is illustrated as being off with respect to the in-plane direction of the main surface 1a (hereinafter also referred to as “main surface lateral direction”). Not limited. For example, the side surface 1b may be configured to be turned off in either the main surface vertical direction or the main surface horizontal direction. In this case, the off angle of the side surface 1b with respect to the (100) plane is a combination of the vectors in the vertical and horizontal tilt directions. That is, for example, when the side surface 1b is turned off by 2 ° in the <001> direction from the main surface (100) and turned off by 2 ° in the <010> direction, by combining these vectors, The off angle is 2.8 ° in the <011> direction.

  Each of the side surfaces 1b to 1e is a surface in contact with the main surface 1a. Therefore, as shown in FIG. 4, when each side surface 1b-1e of the board | substrate 1 is a polyhedral shape, each side surface 1b-1e becomes a surface which is in contact with the main surface 1a in FIG. That is, in the shape shown in FIG. 4, the off angle of the side surface shown perpendicular to the main surface 1a in the drawing is not particularly limited.

  In the diamond composite 10, the side surfaces 1b to 1e of the substrate 1 preferably have a large surface roughness. Specifically, the surface roughness of each of the side surfaces 1b to 1e is preferably 0.5 μm or more, and more preferably 10 μm or more. In this specification, the surface roughness means the maximum height roughness (Rz), and can be measured by, for example, a stylus type surface shape measuring instrument, a scanning white interference microscope, a laser microscope, or the like. In this specification, the value measured by the scanning white interference microscope is described as the surface roughness.

  The present inventors have found that when the surface roughness of the side surface in contact with the main surface of the substrate is large, the residual stress of single crystal diamond obtained from the diamond composite is further reduced. The reason for this is not clear, but it is considered that the growth of the non-diamond carbon is particularly dominant with respect to the growth of the epitaxial growth layer from the side surfaces 1b to 1e of the substrate 1 due to the rough side surface shape.

  In order to increase the surface roughness of each of the side surfaces 1b to 1e, for example, it is preferable that each of the side surfaces 1b to 1e is a surface cut by laser cutting. When single crystal diamond is cut by laser cutting, the surface roughness of the exposed surface increases. In addition, by forming the side surfaces 1b to 1e by laser cutting, it is easy to design the off angles of the side surfaces 1b to 1e.

  Moreover, in the diamond composite 10, the single crystal diamond 2 preferably has a thickness of 0.5 mm or more (for example, the vertical direction in FIG. 1), and more preferably has a thickness of 1 mm or more. Normally, when single crystal diamond is formed on a substrate by CVD, the influence of residual stress increases as the thickness increases, and defects tend to occur. On the other hand, according to the diamond composite 10 of this embodiment, since the residual stress of the single crystal diamond 2 is small, even if the thickness of the single crystal diamond 2 is 0.5 mm or more, the occurrence of defects is sufficiently suppressed. can do.

  As described above in detail, the diamond composite of the present embodiment can include single crystal diamond in which occurrence of defects such as distortion, cracks, and cracks is suppressed. Therefore, when the single crystal diamond separated from the diamond composite is used for a diamond product, the occurrence of defects in the diamond product is suppressed, so that it can be suitably used for a diamond product. Among these, when this single crystal diamond is used for a tool such as a cutting tool, a grinding tool, and an anti-abrasion tool, the characteristics can be remarkably exhibited.

  In the diamond composite of this embodiment, another layer may be interposed between the main surface of the substrate and the single crystal diamond. Examples of the other layer include a conductive layer described later. In the diamond composite, since the conductive layer is interposed between the main surface of the substrate and the single crystal diamond, the single crystal diamond and the substrate can be easily separated.

<Example of method for producing diamond composite>
The diamond composite according to the present embodiment can be produced, for example, as follows.

  Referring to FIG. 2, first, single-crystal diamond produced by a high-temperature and high-pressure method is prepared as a substrate 1. Then, laser cutting is performed so that the off angle of the main surface 1a of the substrate 1 with respect to the (001) plane is 0 ° or more and 7 ° or less, and the surface of the main surface 1a is smoothed by mechanical polishing or the like, and alcohol or acid ( Clean with hot acid. Further, each of the side surfaces 1b to 1e in contact with the main surface 1a of the substrate 2 has an off angle with respect to the (100) plane larger than 8 ° and smaller than 37 °, and an off angle with respect to the (−100) plane larger than 8 ° and 37. Each side surface is a surface smaller than 0 °, a surface having an off angle with respect to the (0-10) surface of greater than 8 ° and smaller than 37 °, and a surface with an off angle with respect to the (010) surface of greater than 8 ° and smaller than 37 °. Laser cutting.

  Next, the substrate 1 subjected to the above processing is placed in an RIE apparatus to remove damage on the main surface 1a caused by mechanical polishing. In the RIE apparatus, since the side surfaces 1b to 1e in contact with the main surface 1a are also exposed to the plasma, it may be feared that even the damage on the side surfaces 1b to 1e is removed. However, the surface roughness of the side surfaces 1b to 1e is larger than that of the main surface 1a, and such a surface can have the same function as when the coating is applied so that the surface is not exposed to plasma. Accordingly, the side surfaces 1b to 1e are not affected by the exposure to the plasma in contrast to the main surface 1a from which the surface damage is removed by the exposure to the plasma.

Next, impurities such as carbon (C), nitrogen (N), silicon (Si), phosphorus (P) or sulfur (S) are ion-implanted into the single crystal diamond layer having the main surface 1a. Thereby, a conductive layer is formed in a depth region less than 1 μm from the surface of main surface 1a. The implantation energy in ion implantation is preferably 250 to 350 keV, and the implantation amount is preferably 5 × 10 ^{15 to} 5 × 10 ¹⁷ ions / cm ³ .

  Next, after the pressure in the vacuum chamber is set to 70 to 110 Torr, a hydrocarbon gas such as methane, a hydrogen gas, and an additive gas such as an inert gas and nitrogen are introduced to form an epitaxial growth layer made of single crystal diamond. It is formed on the main surface 1a. Specifically, first, the mixture is heated to 800 to 1100 ° C. in an apparatus into which only the additive gas and hydrogen gas are introduced, and then the hydrocarbon gas and additive gas are further introduced. Thereby, as shown in FIG. 1, the single crystal diamond 2 which is an epitaxial growth layer is formed on a conductive layer (not shown in FIG. 1). At the same time, the carbonaceous layer 3 is formed so as to cover the side surfaces 1 b to 1 e of the single crystal diamond 2. Since the crystal structure of diamond is maintained on the outermost surface of main surface 1a after the conductive layer is formed, an epitaxially grown layer is formed on main surface 1a after the formation of the conductive layer as described above. Can be made.

As described above, the diamond composite of this embodiment can be produced. With regard to this diamond composite, since the bonding between the single crystal diamond and the carbonaceous layer is weak, both can be easily separated. As a separation method, separation by laser irradiation, separation by removing a carbonaceous layer with a hot mixed acid (240 ° C., HNO ₃ : H ₂ SO ₄ = 1: 3), annealing treatment or plasma treatment in an atmosphere containing oxygen Separation by removing the carbonaceous layer by means of separation, separation by applying a physical impact, or separation by combining these.

  Moreover, although the growth origin of the carbonaceous layer, for example, the lower part of the carbonaceous layer 3 in FIG. 1 is fixed to the side surfaces 1b to 1e of the substrate 1, the bonding between the carbonaceous layer 3 and the substrate 1 is also weak. Therefore, both can be easily separated. Furthermore, according to the diamond composite produced as described above, since the conductive layer is interposed between the substrate and the single crystal diamond, the conductive layer is electrochemically etched to remove the diamond composite from the diamond composite. The substrate can be easily removed. Therefore, as a result, single crystal diamond can be easily separated from the diamond composite.

  In addition, regarding the above-described manufacturing method, the present inventors have made it difficult to grow single crystal diamond on a surface other than the {100} plane, and the growth of single crystal diamond on the {100} plane is particularly dominant. It was found that the diamond composite can be formed more efficiently by making the conditions that are likely to occur, and that the single crystal diamond obtained from this is also of high quality with further reduced occurrence of defects. ing. This is because, under such a condition, single-crystal diamond is particularly easy to grow on the main surface which is the {100} plane, and is off by more than 8 ° and less than 37 ° from the {100} plane. This is probably because the single-crystal diamond is difficult to grow on the side surface, and the growth of the carbonaceous layer is particularly dominant, thereby forming a carbonaceous layer with a high proportion of non-diamond carbon.

  Conditions for the growth of single crystal diamond on the {100} plane are, for example, (1) increasing the amount of hydrocarbons introduced into the vacuum chamber, and (2) introducing nitrogen gas into the vacuum chamber. And the like. Specifically, with regard to (1) above, the volume ratio of hydrocarbon gas to the total amount of gas introduced into the vacuum chamber is preferably 5 to 20% by volume, and 8 to 15% by volume. More preferred. Regarding (2) above, the volume ratio of nitrogen gas to the total amount of gas introduced into the vacuum chamber is preferably 0.005 to 4% by volume, and 0.02 to 1% by volume. More preferred. Further, the above (1) and (2) may be combined. In addition, the volume ratio of hydrocarbon gas is a value converted into carbon. Therefore, for example, when ethane gas is used as the hydrocarbon gas, the volume ratio is half that when methane gas is used.

<Diamond bonded body>
5 and 6 are schematic cross-sectional views of the diamond joined body of the present embodiment. Specifically, FIG. 5 is a schematic cross-sectional view of a diamond bonded body obtained by removing a substrate from a diamond composite, and FIG. 6 is obtained by removing a carbonaceous layer from the diamond composite. It is a schematic sectional drawing of the diamond joined body obtained.

  First, referring to FIG. 5, the diamond bonded body 20 includes a single crystal diamond 2 and a carbonaceous layer 3 covering the side surface 2 b of the single crystal diamond 2, and the carbonaceous layer 3 contains non-diamond carbon. Since the diamond bonded body 20 has a configuration in which the substrate 1 is removed from the diamond composite 10 described above, the same description as above is not repeated. Examples of the method for removing the substrate 1 from the diamond composite 10 include a method of electrochemically etching a portion where an ion implantation layer is formed, a method of cutting by laser irradiation, and the like.

Referring to FIG. 6, the diamond bonded body 30 includes a substrate 1 made of a diamond seed crystal and a single crystal diamond 2 formed in the shape of the main surface 1 a of the substrate 1. Since this diamond bonded body 30 has a configuration in which the carbonaceous layer 3 is removed from the diamond composite 10 described above, the same description as above will not be repeated. As a method of removing the carbonaceous layer 3 from the diamond composite, there is a method of separating the diamond bonded body 30 and the carbonaceous layer 3. Specifically, separation by laser irradiation, separation by removal of a carbonaceous layer with hot mixed acid (240 ° C., HNO ₃ : H ₂ SO ₄ = 1: 3), annealing treatment in an atmosphere containing oxygen, or plasma treatment There are separation by removing the carbonaceous layer, separation by applying a physical impact, or separation by combining these. In the diamond composite 10, the carbonaceous layer 3 is bonded to the substrate 1 and the single crystal diamond 2. However, since the bonding force is low, the carbonaceous layer 3 can be easily removed. The joined body 30 can be easily formed from the diamond composite 10.

  The diamond joined body of the present embodiment is obtained by removing the substrate or the carbonaceous layer from the above-mentioned diamond composite, and the single crystal diamond included in these is compared with the single crystal diamond that is a conventional epitaxial growth layer. Therefore, there is little distortion and the frequency of occurrence of defects such as cracks and cracks is low. Therefore, the diamond joined body of this embodiment can provide single crystal diamond suitable for diamond products.

<Single crystal diamond>
FIG. 7 is a schematic cross-sectional view of the single crystal diamond of the present embodiment. Referring to FIG. 7, single crystal diamond 2 is a single crystal diamond obtained by removing substrate 1 and carbonaceous layer 3 from diamond composite 10, and is an epitaxially grown layer having main surface 2a and side surface 2b. .

  The single crystal diamond of the present embodiment is a single crystal diamond separated from the above-mentioned diamond composite, has less distortion than the conventional single crystal diamond that is an epitaxial growth layer, and also generates cracks, cracks, etc. Infrequent. Therefore, the single crystal diamond of this embodiment can be suitably used for diamond products.

<Tool>
FIG. 8 is a schematic cross-sectional view of a diamond tool that is an example of the tool of the present embodiment. Referring to FIG. 8, the diamond tool 50 mainly includes a base metal 4, a brazing layer 5, a metallized layer 6, and a single crystal diamond 22. The single crystal diamond 22 is fixed to the base metal 4 via the brazing layer 5 and the metallized layer 6. The single crystal diamond 22 includes a rake face 22b and a flank face 22c, and a cutting edge 22d is formed at a contact portion between the rake face 22b and the flank face 22c.

  The single crystal diamond 22 included in the diamond cutting tool 50 is obtained by appropriately processing the above-described single crystal diamond into a desired shape. In other words, the tool of the present embodiment is a tool including the above-described single crystal diamond. The single crystal diamond described above is less distorted and has a lower frequency of occurrence of cracks, cracks, etc. than the single crystal diamond that is a conventional epitaxial growth layer. Therefore, according to the tool of the present embodiment using this, since the occurrence of distortion, cracks, cracks, etc. in the single crystal diamond portion is suppressed, it can have a long service life, and due to tool breakage, etc. The damage of the to-be-processed member which arises can be suppressed. Therefore, the tool of this embodiment can have high performance as a tool.

  Further, the tool of the present invention is not limited to the tool such as the diamond cutting tool 50 described above, and for example, a drill, an end mill, a cutting edge replacement cutting tip for a drill, a cutting edge replacement cutting tip for an end mill, and a cutting edge replacement cutting for milling. Other cutting tools such as a tip, a cutting edge exchangeable cutting tip for turning, a metal saw, a gear cutting tool, a reamer, and a tap may be used. The tool of the present invention is not limited to a cutting tool, and may be a grinding tool, an anti-wear tool, a part, or the like. Examples of the grinding tool include a dresser. Examples of the wear-resistant tool and parts include a die, a scriber, a water or powder jet nozzle, and a guide such as a wire.

<Examination 1>
In Study 1, various substrates with different side surface orientations were prepared, and samples (No. 1 to 10) in which single crystal diamond was formed on each substrate by the CVD method under the same conditions were prepared and manufactured. Each sample was evaluated. This will be specifically described below.

(Production of substrate)
Referring to FIG. 2, first, a substrate 1 (thickness: 500 μm, 5 mm square) made of Ib type single crystal diamond produced by a high-temperature high-pressure method was prepared as a substrate. The plane orientation of the main surface 1a of the substrate 1 is the (001) plane, and the plane orientations of the side faces 1b to 1e are (100) plane, (-100) plane, (0-10) plane, (010) plane. there were.

The main surface 1a of the prepared substrate is mechanically polished so as to be turned off by 2 ° in the [100] direction from the (001) plane, and then mechanically polished to such an extent that a polishing flaw cannot be observed with a differential interference microscope. Etching was performed by 2 μm in the thickness direction by RIE using oxygen gas and CF ₄ gas. Further, with respect to the side surfaces 1b to 1e of the prepared substrate, the side surfaces are set so that the off angle in the vertical direction of the main surface and the off angle in the main surface lateral direction (that is, the in-plane direction of the main surface) are the values shown in Table 1. Laser cut.

  Here, the off angles shown in Table 1 are absolute values. That is, with respect to the longitudinal direction of the main surface, both the case where it is turned off in the direction shown in FIG. 3A and the case where it is turned off in the direction shown in FIG. Both the case where it was turned off in the direction shown in FIG. 3C and the case where it was turned off in the direction shown in FIG. Since the same result was obtained when turning off in either direction with respect to the longitudinal direction of the principal surface and the transverse direction of the principal surface, in Table 1, each off angle is indicated by an absolute value.

(Formation of single crystal diamond)
First, ion implantation using carbon was performed on the main surface 1a of each substrate 1 produced. The ion implantation energy was 330 keV, and the implantation amount was 1 × 10 ¹⁷ ions / cm ³ . As a result, an excessive conductive layer of carbon was formed in a portion slightly (less than 1 μm) inside the thickness direction on the main surface 1a of the substrate 1. A layer having a diamond structure remained on the outermost surface. Each substrate 1 was placed in a vacuum chamber of a microwave plasma CVD apparatus so that the main surface 1a was exposed. Then, the substrate 1 is heated at a temperature of 1100 ° C. and the pressure in the vacuum chamber is set to 90 Torr. Then, hydrogen gas, methane gas, and nitrogen gas are introduced into the vacuum chamber, and microwave plasma CVD is performed. A single crystal diamond layer having a thickness of 0.5 mm was formed. The mixing ratio (volume%) of each gas at this time was hydrogen gas: methane gas: nitrogen gas = 91.5: 8: 0.5.

  In the formation of single crystal diamond, an ion implantation process is not essential, but there is an advantage that the substrate 1 and the single crystal diamond can be easily separated by electrochemically etching the conductive layer formed by the ion implantation process. Further, in both cases where the ion implantation process is performed and when the ion implantation process is not performed, a method of separating the substrate 1 and the single crystal diamond by laser processing can be employed when obtaining the single crystal diamond.

  Next, the substrate 1 is subsequently heated at a temperature of 1100 ° C., the pressure in the vacuum chamber is set to 90 Torr, hydrogen gas, methane gas, and nitrogen gas are introduced into the vacuum chamber to perform microwave plasma CVD, Single-crystal diamond having a thickness of 1.5 mm was formed on the surface on which the conductive layer was formed. The mixing ratio (volume%) of each gas at this time was hydrogen gas: methane gas: nitrogen gas = 91.5: 8: 0.5.

(Evaluation)
Regarding samples 1 to 10, it was visually confirmed that in each of samples 3, 4, 7, 8 and 9 (examples), a layer covering the side surface of the single crystal formed on substrate 1 was formed. It was. Further, when the layer was separated from the single crystal diamond by laser cutting and subjected to SEM observation, Raman spectroscopic analysis, and EELS analysis, it was understood that the layer was a carbonaceous layer containing a large amount of graphite. However, in the observation, care was taken not to include graphite scattered by laser cutting.

  In addition, regarding Samples 1, 2, 5, 6 and 10 (Comparative Example) and Samples 3, 4, 7, 8 and 9 (Examples) after removal of the carbonaceous layer, the conductive layer was electrochemically etched to form a substrate. The single crystal diamond was separated by removing, and the presence or absence of cracks in the separated single crystal diamond was confirmed. In addition, the crack means a defect in a relatively minute cleavage state inside the crystal, and the crack means a defect in a cleavage state that is larger than the crack where the crack appears on the surface of the crystal. . In the confirmation, a distinction was made based on whether or not the cleavage appeared as a crack on the surface of the crystal, not the magnitude relationship. The results are shown in Table 1.

  Referring to Table 1, in Samples 3, 4, 7, 8, and 9, no defects were confirmed. Moreover, generation | occurrence | production of a crack was confirmed in the samples 2, 6 and 10, and generation | occurrence | production of the crack and a crack was confirmed in the sample 5. In addition, in samples 1 and 2, a sample that is not ion-implanted was separately prepared, and the same evaluation was performed when the substrate and the single crystal diamond were separated by laser treatment. The results were the same as those of Samples 1 and 2 shown in Table 1. That is, it was found that the method for separating the substrate and single crystal diamond had no influence on the evaluation of the occurrence of defects.

  In addition, regarding the sample 9, when showing one geometric orientation, the off-angle in the <011> direction with respect to the (100) plane of the side surface 1b, and the <0-11> direction with respect to the (-100) plane of the side surface 1c. The off angle, the off angle in the <101> direction with respect to the (0-10) plane of the side surface 1d, and the off angle in the <−101> direction with respect to the (010) plane of the side surface 1e are each 8.5 °. Further, regarding the sample 10, the off angle in the <011> direction with respect to the (100) plane of the side surface 1b, the off angle in the <0-11> direction with respect to the (-100) plane of the side surface 1c, and (0-10) of the side surface 1d. The off angle in the <101> direction with respect to the () plane and the off angle in the <−101> direction with respect to the (010) plane of the side surface 1e are each 7.1 °. That is, for samples 9 and 10, the off angles shown in Table 1 are off angles obtained by vector synthesis of the directions of the off angles.

<Examination 2>
In Study 2, various substrates with different side surface orientations and side surface roughnesses were prepared, and single crystal diamond was formed on each substrate by the CVD method under different conditions with different amounts of methane gas introduced (No. .11 to 20), and each of the produced samples was evaluated. This will be specifically described below.

(Production of substrate)
Referring to FIG. 2, first, a substrate 1 (thickness: 500 μm, 5 mm square) made of Ib type single crystal diamond produced by a high-temperature high-pressure method was prepared as a substrate. The plane orientation of the main surface 1a of the substrate 1 is the (001) plane, and the plane orientations of the side faces 1b to 1e are (100) plane, (-100) plane, (0-10) plane, (010) plane. there were.

The main surface 1a of the prepared substrate is laser-cut so that it is turned off by 2 ° in the [100] direction from the (001) plane, and then mechanically polished to such an extent that polishing scratches cannot be observed with a differential interference microscope. Etching was performed by 2 μm in the thickness direction by RIE using oxygen gas and CF ₄ gas. Further, with respect to the side surfaces 1b to 1e of the prepared substrate, each side surface was laser-cut so that the off angle in the vertical direction of the main surface and the off angle in the horizontal direction of the main surface became values shown in Table 2.

  Here, the off angles shown in Table 2 are absolute values. That is, with respect to the longitudinal direction of the main surface, both the case where it is turned off in the direction shown in FIG. 3A and the case where it is turned off in the direction shown in FIG. Both the case where it was turned off in the direction shown in FIG. 3C and the case where it was turned off in the direction shown in FIG. Since the same result was obtained when turning off in either direction with respect to the longitudinal direction of the principal surface and the transverse direction of the principal surface, in Table 2, each off angle is indicated by an absolute value.

  Further, as shown in Table 2, with respect to Samples 11 to 14, 17 and 19, the side surfaces 1d to 1e were mechanically polished by adjusting the load and rotation speed to reduce the surface roughness. However, the degree of polishing was adjusted so that the surface roughness of the side surface after mechanical polishing was larger than the surface roughness of the side surface when a general polishing process was performed. The value of the surface roughness shown in Table 2 is the value of the surface roughness of the side surface after polishing for the sample that was polished, and the value of the surface roughness of the side surface after laser cutting for the sample that was not polished.

(Formation of single crystal diamond)
A conductive layer and single crystal diamond were formed on the substrate 1 by the same method as in Study 1 except that the mixing ratio (volume%) of methane gas in the microwave plasma CVD method was changed in the range of 6 to 12 volume%. The mixing ratio of methane gas in each sample is as shown in Table 2, and the amount of hydrogen gas introduced also changed with this change. However, the mixing ratio of nitrogen gas was always 0.5% by volume.

(Evaluation)
In all of Samples 11 to 20 (Examples), it was visually confirmed that a layer covering the side surface of the single crystal formed on the substrate 1 was formed. Further, when the layer was separated from the single crystal diamond by laser cutting and subjected to SEM observation, Raman spectroscopic analysis, and EELS analysis, it was understood that the layer was a carbonaceous layer containing a large amount of graphite.

Moreover, regarding the samples 11 to 20 after removing the carbonaceous layer, the single-crystal diamond was separated by electrolytically etching the conductive layer to remove the substrate, and the residual stress of the separated single-crystal diamond was measured. The residual stress was measured using Raman spectroscopy. Specifically, the residual stress was converted to stress by multiplying the shift amount of the peak at 1332 cm ⁻¹ by a constant. The results are shown in Table 2.

  Referring to Table 2, it was confirmed that the residual stress was sufficiently reduced when the surface roughness of the side surface of the substrate was 0.2 μm or more. In particular, it was confirmed that the residual stress was more sufficiently reduced when the surface roughness of the side surface of the substrate was 0.7 μm or more. In particular, it was confirmed that it is preferable to use a substrate having a laser-cut side surface that is not mechanically polished. However, good results as shown in Table 2 were not obtained even when the surface roughness was set to be equal to or greater than the thickness of the substrate. Moreover, in the range shown in Table 2, it turned out that a residual stress is so small that the introduction ratio of the methane gas in CVD method is high. Further, it was found that the residual stress was particularly small when the surface roughness of the side surface of the substrate was high and the introduction ratio of methane gas was high. In addition, the residual stress of the single crystal diamond which is the epitaxial growth layer formed by the normal CVD method is larger than the residual stress of the single crystal diamond of Samples 11 to 20.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 substrate, 2 single crystal diamond, 3 carbonaceous layer, 4 base metal, 5 brazing layer, 10 diamond composite, 20, 30 diamond bonded body, 40 single crystal diamond.

Claims (10)

A substrate made of a diamond seed crystal;
Single-crystal diamond formed on the main surface of the substrate;
A carbonaceous layer covering a side surface of the single crystal diamond,
The carbonaceous layer is a diamond composite comprising non-diamond carbon.   The diamond composite according to claim 1, wherein 1% by volume or more of the carbonaceous layer is the non-diamond carbon. The main surface of the substrate has an off angle with respect to the (001) plane of 0 ° or more and 7 ° or less,
The side surface of the substrate in contact with the main surface has a first side surface having an off angle with respect to the (100) plane of greater than 8 ° and smaller than 37 °, and a first side surface with an off angle with respect to the (-100) surface of greater than 8 ° and smaller than 37 °. Two side surfaces, a third side surface with an off angle greater than 8 ° and smaller than 37 ° with respect to the (0-10) plane, and a fourth side surface with an off angle with respect to the (010) plane greater than 8 ° and smaller than 37 °. The diamond composite according to claim 1 or claim 2.   The diamond composite according to any one of claims 1 to 3, wherein the single crystal diamond has a thickness of 0.5 mm or more. A method for producing a diamond joined body, wherein a diamond joined body containing the single crystal diamond is obtained by removing the substrate or the carbonaceous layer from the diamond composite according to any one of claims 1 to 4. The manufacturing method of a single crystal diamond which obtains the said single crystal diamond by removing the said board | substrate and the said carbonaceous layer from the diamond composite_body | complex of any one of Claims 1-4. A tool comprising the single-crystal diamond included in the diamond composite according to any one of claims 1 to 4 on a base metal . Preparing a substrate which is a diamond seed crystal;
Growing a carbonaceous layer containing non-diamond carbon covering the side surface of the single crystal diamond on the side surface of the substrate while growing single crystal diamond on the main surface of the substrate;
A method for producing single crystal diamond, comprising a step of removing the substrate and the carbonaceous layer. A diamond joined body comprising single crystal diamond and a carbonaceous layer present on a side surface of the single crystal diamond and containing non-diamond carbon,
The main surface of the single crystal diamond has an off angle with respect to the (001) plane of 0 ° or more and 7 ° or less,
The side surface in contact with the main surface includes a first side surface having an off angle with respect to the (100) plane of greater than 8 ° and less than 37 °, and a second side surface with an off angle with respect to the (-100) surface of greater than 8 ° and less than 37 °. And a third side surface having an off angle greater than 8 ° and smaller than 37 ° with respect to the (0-10) plane, and a fourth side surface having an off angle greater than 8 ° and smaller than 37 ° with respect to the (010) plane body. A single crystal diamond having a main surface and side surfaces,
The main surface has an off angle with respect to the (001) plane of 0 ° or more and 7 ° or less,
The side surface in contact with the main surface includes a first side surface having an off angle with respect to the (100) plane of greater than 8 ° and less than 37 °, and a second side surface with an off angle with respect to the (-100) surface of greater than 8 ° and less than 37 °. And a third side surface having an off angle greater than 8 ° and smaller than 37 ° with respect to the (0-10) plane, and a fourth side surface having an off angle greater than 8 ° and smaller than 37 ° with respect to the (010) plane. diamond.

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