JP4340881B2 - Diamond manufacturing method - Google Patents

Description

  The present invention relates to a method for producing diamond, and particularly to a method for producing a large diamond single crystal suitable for a semiconductor device substrate or an optical component.

  Since diamond has many excellent properties such as high hardness, high thermal conductivity, high light transmittance, wide band gap, etc., it is widely used as a material for various tools, optical parts, semiconductors, electronic parts, In the future, it will be even more important. In the past, naturally occurring diamonds have been used for industrial applications, but now industrial applications are mainly artificially synthesized. Diamond single crystals are currently synthesized industrially under pressures of tens of thousands of atmospheric pressures at which they are stable. Such an ultra-high pressure vessel that generates a high pressure is very expensive and has a limited size. Therefore, there is a limit to the synthesis of a large single crystal by a high-temperature and high-pressure method. As for the Ib type diamond having a yellow color containing nitrogen (N) as an impurity, a 1 cmφ class diamond is synthesized and sold by a high pressure synthesis method, but this size is considered to be almost the limit. Further, the colorless and transparent type IIa diamond having no impurities is limited to a smaller one of several mmφ or less, except for natural ones.

  On the other hand, a gas phase synthesis method is established as a diamond synthesis method along with a high pressure synthesis method. According to this method, those having a relatively large area of several cm to 10 cmφ are artificially manufactured, but these are usually polycrystalline films. However, it is necessary to use single crystal diamond when used for ultra-precision tools, optical parts, semiconductors, etc. that require a smooth surface, among diamond applications. Therefore, methods for obtaining single crystal diamond by epitaxial growth by vapor phase synthesis have been studied.

  In general, the epitaxial growth is considered to be homoepitaxial growth in which a growing material is grown on the same type of substrate and heteroepitaxial growth in which a growth material is grown on a different type of substrate. In heteroepitaxial growth, cubic boron nitride (cBN), silicon carbide, silicon, nickel, cobalt, and the like have been reported so far (see Patent Documents 1 to 3), but single crystals with good film quality have been obtained by heteroepitaxial growth. Therefore, single crystal synthesis by homoepitaxial growth is considered to be dominant. In homoepitaxial growth, high-purity diamond is epitaxially grown from a gas phase on a diamond Ib substrate by high-pressure synthesis, whereby a large IIa single crystal diamond that exceeds IIa diamond obtained at high pressure can be obtained. It has also been reported that a diamond having only a low-angle grain boundary can be obtained by using a plurality of diamond substrates or diamond grains oriented in the same crystal orientation and growing a single diamond thereon (patent) Reference 4).

  However, a problem in synthesizing diamond by homoepitaxial growth is a method for removing and reusing a substrate. When an IIa diamond film is obtained by vapor phase synthesis using Ib diamond or the like as a substrate, it is necessary to remove the Ib diamond substrate from the grown diamond layer by some method. As a method for this, a method of separating the epitaxial film and the substrate or a method of eliminating the substrate at all can be considered. Since the diamond single crystal substrate is expensive, it is needless to say that the former method is desirable, and slicing is a typical method. However, the larger the diamond area, the thicker the diamond is needed for slicing and the worse the success rate.

  For this reason, when the diamond has a size of 1 cm × 1 cm, slicing is no longer difficult, and a method of removing the substrate must be used.

  For this, polishing using diamond abrasive grains, a method of removing a layer reacted with an iron surface and reacting (for example, see Patent Document 5), a method by ion beam irradiation (see Patent Document 6), and the like are known. Both of them take a long time. In addition, the inability to reuse a substrate by high-pressure synthesis is a significant disadvantage in terms of cost. Parik et al. Have reported a method of removing a diamond single crystal film of μm order from a substrate by implanting oxygen (O) ions accelerated to several MeV into the diamond surface and heating (N. R. Parikh et al. Appl. Phs. Lett. 61 (1992) 3124). However, this method is very difficult to handle due to warping and the like, which is caused by distortion that appears due to thermal stress in the separated diamond layer when heated and separated.

  In addition, Tomikawa et al. Proposed a method of obtaining a diamond epitaxial growth film independent of the substrate by heteroepitaxial growth of nickel (Ni) and diamond in this order on diamond and then dissolving Ni in the intermediate layer ( (See Patent Document 7). As described above, this method is also based on the diamond heteroepitaxial technique which is not so good, and there remains a problem in terms of film quality.

  Furthermore, Tsukino et al. Proposed a method of recycling an expensive diamond substrate by cutting a semiconductor diamond layer by electric discharge machining (see Patent Document 8). This method provided a simple method for regenerating a diamond substrate, but when taking out a plurality of insulating diamond layers, it is necessary to perform electric discharge machining for each layer. There was a limit. In addition, it is not possible to cut a diamond layer of any thickness after growing the diamond, and it is necessary to build a semiconductor diamond layer according to the thickness to be cut in advance, and the degree of freedom of the process is not high. .

From such a situation, a film having good crystallinity is epitaxially grown on a diamond single crystal by vapor phase synthesis, without damaging both the diamond epitaxial film and the substrate diamond, and without deteriorating the crystallinity, There has been a strong demand for a method that enables high-speed separation and reuse of the substrate.
JP-A-63-224225 JP-A-2-233591 JP-A-4-132687 Japanese Patent Laid-Open No. 3-75298 JP-A-2-26900 Japanese Patent Application Laid-Open No. 64-68484 JP-A-1-266825 Japanese Patent Application Laid-Open No. 7-69795

  As described above, in the conventional technology, even if high-purity large-area diamond is epitaxially grown to grow a high-quality diamond single crystal, in order to use epitaxial diamond alone, the substrate can be reused. It was difficult to remove with a method, and a method of removing in a non-reusable form had to be used.

  The object of the present invention is to solve such problems of the prior art, perform epitaxial growth on a diamond substrate by vapor phase synthesis, and separate the diamond epitaxial film and the substrate diamond without damaging them. It is in providing the manufacturing method of.

  The inventors of the present invention can selectively etch only semiconductor diamond by electrochemical etching if a semiconductor diamond layer is first grown from a vapor phase on a diamond substrate and an insulating diamond layer is grown thereon. And separating the substrate and the insulating diamond layer, and found that the substrate can be reused.

  In addition, when a plurality of semiconductor diamond layers and insulating diamond layers are alternately laminated, by using electrochemical etching, only all the semiconductor diamond layers can be selectively etched. It was found that can be separated efficiently.

Furthermore, even after the insulating diamond layer is grown on the diamond substrate, the maximum value of the atomic concentration is in the range of 5 × 10 ¹⁸ to 2 × 10 ²¹ atoms / cm ^{3 at} the depth to be separated by ion implantation. After implanting ions to form an implanted layer and imparting conductivity, the insulating diamond layer and the substrate can be separated by electrochemical etching or electrical discharge machining, and the substrate can be reused. I found it.

  In the ion implantation in the present invention, a desired element is ionized, separated by a mass spectrometer, and then introduced into a sample by applying a high voltage. The distribution of the introduced ions in the depth direction can be designed according to the ions to be introduced, the high voltage to be applied, the element of the sample, the density, and the like. In the present invention, the injection layer is injected so as to be a continuous layer on the substrate. By injecting while changing the applied voltage, the thickness of the injection layer can be adjusted. Furthermore, by increasing the change width of the voltage to be applied, a layer in which implanted ions are not substantially present between the implanted layers for each voltage is formed, and this remains an insulating diamond. That is, a plurality of insulating diamond layers sandwiched between a plurality of injection layers can be formed.

That is, the present invention has the following configuration.
(1) a step of growing a semiconductor diamond layer on a diamond substrate by a vapor phase synthesis method;
A step of growing an insulating diamond layer thereon by vapor phase synthesis;
A method for producing diamond, comprising: a step of separating the insulating diamond layer and the diamond substrate by etching the semiconductor diamond layer by an electrochemical technique.
(2) a step of alternately laminating a plurality of semiconductor diamond layers and insulating diamond layers on a diamond substrate in the order of a semiconductor diamond layer and an insulating diamond layer by a vapor phase synthesis method;
A method for producing diamond, comprising a step of separating the plurality of insulating diamond layers and the diamond substrate by etching the plurality of semiconductor diamond layers by an electrochemical technique.

(3) The method for producing diamond according to (1) or (2), wherein at least one of the diamond substrate, the semiconductor diamond layer, and the insulating diamond layer is single crystal diamond. Diamond manufacturing method.
(4) The method for producing diamond according to (1) or (2), wherein the etching by an electrochemical method is performed by immersing diamond in an aqueous electrolyte solution and applying an electric potential to the electrode. A method for producing diamond, wherein a material to be etched is disposed on an anode, and an organic acid or an alcohol is present in an aqueous electrolyte solution.

(5) a step of growing insulating diamond on the diamond substrate by vapor phase synthesis;
Ion implantation is performed so that an implantation layer having a maximum atomic concentration of 5 × 10 ¹⁸ atoms / cm ³ or more and 2 × 10 ²¹ atoms / cm ³ or less is formed immediately above the diamond substrate from the surface of the insulating diamond. Implanting ions of the atoms by the method,
A method for producing diamond, comprising a step of subjecting the injection layer to electrical discharge machining to separate the diamond substrate and the insulating diamond layer.
(6) a step of growing insulating diamond on the diamond substrate by vapor phase synthesis;
Ion implantation is performed so that an implantation layer having a maximum atomic concentration of 5 × 10 ¹⁸ atoms / cm ³ or more and 2 × 10 ²¹ atoms / cm ³ or less is formed immediately above the diamond substrate from the surface of the insulating diamond. Implanting ions of the atoms by the method,
A method for producing diamond, comprising a step of separating the diamond substrate and the insulating diamond layer by etching the injection layer by an electrochemical technique.

(7) In the method for producing diamond according to (5) or (6), ions to be used are ions selected from carbon, argon, helium, hydrogen, silicon, germanium, and tin. A method for producing diamond characterized.
(8) The method for producing diamond according to any one of (5) to (7), wherein at least one of the diamond substrate and the insulating diamond layer is single crystal diamond. Method.
(9) The method for producing diamond according to (6), wherein the etching by an electrochemical method is performed by immersing diamond in an electrolyte aqueous solution and applying an electric potential to the electrode, Is disposed on the anode, and an organic acid or alcohol is present in the aqueous electrolyte solution.

  By using the diamond manufacturing method according to the present invention, the diamond seed crystal can be used efficiently, so that diamond can be manufactured at low cost. Further, it becomes easy to produce a large diamond single crystal that has been difficult to process conventionally.

  The diamond substrate in the present invention may be single crystal or polycrystal, but single crystal diamond is more expensive and is preferable because the effects of the present invention can be exhibited more greatly.

  Insulating diamond and semiconductor diamond in the present invention may be single crystal or polycrystalline, but a self-supporting plate of polycrystalline diamond can be obtained relatively easily without using this method. It is more preferable to use single crystal diamond.

  The semiconductor diamond referred to in the present invention is grown by a vapor phase synthesis method. The growth method may be any known method, but it is preferable that the resistivity be as low as possible. The dopant preferably contains B (boron), but may contain one or more dopants such as B, N (nitrogen), P (phosphorus), S (sulfur), or Li (lithium).

  The insulating diamond referred to in the present invention is grown by a vapor phase synthesis method. The growth method may be any known method. Since an insulating diamond substrate as a final product is obtained from this portion, it is desirable that the crystallinity is as good as possible.

  The electrochemical etching referred to in the present invention causes water to be electrolyzed on the diamond surface by immersing diamond in an aqueous electrolyte solution and applying a certain potential to the reference electrode. When diamond is arranged on the cathode, hydrogen gas is generated only on the surface of the semiconductor diamond. At this time, some protons permeate the interface between the semiconductor diamond and the insulating diamond, and hydrogen gas is generated at the interface, whereby the interface between the semiconductor diamond and the insulating diamond can be separated. On the contrary, when it is arranged on the anode, oxygen is generated on the surface of the semiconductor diamond, and this oxygen gas selectively etches the semiconductor diamond, whereby the insulating diamond and the semiconductor diamond can be separated. Unlike the separation by electric discharge machining, it is easy to simultaneously process a plurality of semiconductor diamond layers by simultaneously applying a potential to the plurality of semiconductor diamond layers to separate the plurality of insulating diamond layers from the diamond substrate.

In particular, when diamond is placed on the anode, if organic acids such as formic acid and acetic acid, or alcohols such as methanol and ethanol are dissolved in the aqueous electrolyte solution, semiconductor diamond is etched very efficiently due to these effects. I found out. It has also been found that the etching efficiency can be dramatically improved by supplying an electrolytic current with a current density exceeding 10 A / cm ² or more.

When the thickness of the insulating diamond layer to be taken out is known in advance, the insulating diamond layer to be taken out can be obtained by determining the lamination conditions of the semiconductor diamond layer and the insulating diamond layer based on the thickness. Otherwise, the method of laminating the semiconductor diamond layer by the vapor phase synthesis method cannot be an appropriate method. On the other hand, the method of forming a conductive layer (implanted layer) by ion implantation is not limited to just above the diamond substrate, but after the insulating diamond layer is formed, the conductive layer is formed at an arbitrary depth of the insulating diamond layer. Since a desired insulating diamond layer can be obtained by forming, the degree of freedom in design is high. In the present invention, ions of the atoms are implanted by an ion implantation method so as to form an implanted layer in which the maximum value of the atomic concentration is in the range of 5 × 10 ¹⁸ atoms / cm ^{3 to} 2 × 10 ²¹ atoms / cm ^3. Thus, it has been found that the conductivity of the conductive layer is increased, and the substrate can be easily separated from the substrate by electrical discharge machining and electrochemical etching. When the injection amount is too small, the electrical conductivity is low, and the efficiency of electric discharge machining or electrochemical etching is extremely reduced. On the other hand, if the injection amount is too large, the damage due to the injection of the near-surface layer reaches a level that cannot be ignored, and it becomes impossible to maintain good crystallinity.

The distribution of the implanted ions in the depth direction can be obtained by Monte Carlo simulation by determining the constituent atoms and density of the target material, and the mass and energy of the implanted ions. Conversely, if the required depth and density of the injection layer are determined, the required injection energy and injection amount can be determined. If it is desired to separate a plurality of insulating diamond layers, the implantation energy and the implantation amount may be determined so as to form a plurality of implantation layers. The ions to be used are not particularly limited, but light atoms are preferable because they can be implanted deeply with the same energy, and when the implantation is carried out at the same depth, the distribution in the depth direction profile can be small. In addition, the inert gas, carbon that is a constituent element of diamond, and the same group IV element as carbon have little influence on crystallinity, electrical characteristics, and optical characteristics when remaining outside the desired implantation depth region. This is preferable because it can be completed. For these reasons, the ion species used by carbon, argon, helium, hydrogen, silicon, germanium, and tin are preferable. Usually, when these ions are implanted so as to form an implanted layer having a maximum atomic concentration in the range of 5 × 10 ¹⁸ atoms / cm ^{3 to} 2 × 10 ²¹ atoms / cm ³ , sp3 of diamond carbon atoms The structure is destroyed and partially has an sp2 structure. Since the sp2 structure has conductivity, the ion implantation layer has conductivity.

  By forming the ion-implanted conductive layer in this way and then cutting and etching the formed conductive layer by an electric discharge machining method or an electrochemical etching method, the insulating diamond layer can be cut out. If an ion-implanted conductive layer is formed in the insulating diamond layer portion immediately above the diamond single crystal substrate, the insulating diamond layer and the diamond single crystal substrate can be taken out and the diamond single crystal substrate can be recycled. Of course, if a plurality of ion-implanted conductive layers are formed, a plurality of insulating diamond layers can be cut out.

(Example 1)
A high-pressure synthetic diamond single crystal IIa substrate having a size of 2.5 × 2.5 × 0.5 mm was prepared. The plane orientation of the main surface was {111}. On this, B (boron) dope diamond having a thickness of 5 μm was grown using a 1.5% methane-hydrogen gas by a microwave plasma CVD method. Further, an insulating diamond having a thickness of 300 μm was grown thereon by a hot filament CVD method. The insulating diamond was confirmed to be a single crystal by X-ray diffraction.

The insulating diamond / B (boron) doped diamond / single crystal substrate structure sample thus obtained was subjected to the following electrochemical etching.
An aqueous solution in which sodium sulfate was dissolved at a concentration of 0.2 mol / liter was used as the electrolyte. The above sample was set as a working electrode, and a potential of −20 V was applied to the working electrode using the silver-silver chloride electrode as a reference electrode. The working electrode was connected to the B-doped layer, and the back surface of the substrate was protected with a resin. Then, it was confirmed that a large amount of hydrogen was generated from the exposed portion of the boron-doped diamond on the side surface. The flowing current was about 500 A / cm ² per unit area of the exposed portion of the boron-doped diamond.

  When it is confirmed after treatment for 1 hour, peeling occurs from the interfaces of both the insulating diamond / B-doped diamond and the B-doped diamond / single crystal substrate, and the whole surface is peeled by further treatment for 3 hours. The crystal and single crystal substrate could be separated. In both cases, B-doped diamond partially remained on the separated surfaces, but could be removed by simple machining, and the single crystal substrate could be recycled.

(Example 2)
A high-pressure synthetic diamond single crystal Ib substrate having a size of 2.5 × 2.5 × 0.3 mm was prepared. The plane orientation of the main surface was {100}. On this, a laminated structure of a B-doped diamond layer and an insulating diamond layer was formed by microwave plasma CVD using methane 1% -hydrogen gas, and as a result, insulating diamond as shown in FIG. A diamond having a laminated structure of / B-doped diamond was obtained. As a result of evaluating the outermost surface by the electron diffraction method, it was confirmed to be a single crystal. The sample thus obtained was subjected to the following electrochemical etching.

As an electrolyte, an aqueous solution dissolved at a concentration of 0.15 mol / liter of sodium sulfate was used. The above sample was set as a working electrode, and a potential of +15 V was applied to the working electrode using the silver-silver chloride electrode as a reference electrode. The working electrode was connected to all the B-doped layers, and the back surface of the substrate was protected with a resin. Then, it was confirmed that a large amount of oxygen was generated from the exposed portion of the boron-doped diamond on the side surface. The flowing current was about 300 A / cm ² per unit area of the exposed portion of the boron-doped diamond.

  When the side surface was confirmed after the treatment for 2 hours, it was confirmed that the portion of the B-doped diamond layer was intensively etched. After further treatment for 20 hours, the etching of the side surface of the B-doped layer progressed to the entire surface, and all the insulating diamond layers and the single crystal substrate could be separated. B-doped diamond partially remained on the separated surface, but could be removed by simple machining, and the single crystal substrate could be recycled. The obtained insulating diamond single crystal had good half-value widths of the rocking curve on the (400) plane by the double crystal X-ray diffraction method of 30 seconds, 45 seconds, and 35 seconds from the substrate side.

(Example 3)
In this example, a natural Ia diamond single crystal (3 × 5 × 0.25 mm) was prepared. The plane orientation of the main surface was {100}. On this, a laminated structure of a B-doped diamond layer and an insulating diamond layer was formed by microwave plasma CVD using methane 4% -hydrogen gas, and as a result, insulating diamond as shown in FIG. A diamond having a laminated structure of / B-doped diamond was obtained. As a result of evaluating the outermost surface by the electron diffraction method, it was confirmed to be a single crystal. The sample thus obtained was subjected to the following electrochemical etching.

As an electrolyte, acetic acid was further mixed at a concentration of 1 mol / liter with an aqueous solution dissolved at a concentration of 0.25 mol / liter of sodium sulfate. The above sample was set as a working electrode, and a potential of +20 V was applied to the working electrode using a silver-silver chloride electrode as a reference electrode. The working electrode was connected to all the B-doped layers, and the back surface of the substrate was protected with a resin. Then, it was confirmed that a large amount of oxygen was generated from the exposed portion of the boron-doped diamond on the side surface. The flowing current was about 350 A / cm ² per unit area of the exposed portion of the boron-doped diamond.

  When the side surface was confirmed after the treatment for 5 hours, the etching of the side surface of the B-doped layer proceeded to the entire surface, and all the insulating diamond layers and the single crystal substrate were separated. B-doped diamond partially remained on the separated surface, but could be removed by simple machining, and the single crystal substrate could be recycled. In the obtained insulating diamond single crystal, the half-value width of the rocking curve of the (400) plane according to the double crystal X-ray diffraction method was good at 40 seconds, 45 seconds, and 55 seconds from the substrate side.

(Example 4)
In this example, a natural IIa diamond single crystal (4 × 4 × 0.3 mm) was prepared. The plane orientation of the main surface was {100}. On this, an insulating diamond layer of 120 μm was formed by microwave plasma CVD using a methane 2% -hydrogen system.
After the growth surface was flattened by mechanical polishing, hydrogen ions were implanted from the growth surface. The injection energy was 5 MeV, and the injection amount was 1.5 × 10 ¹⁷ ions / cm ² . The implantation profile in the depth direction is as shown in FIG. 3. At the interface of the insulating diamond / single crystal substrate, a thickness of about 10 μm is 5 × 10 ¹⁸ pieces / cm ³ or more, and a maximum of 2 × 10 ²⁰ pieces / cm ³ . It becomes the injection amount.

  This injection layer showed conductivity, and the insulating diamond layer (thickness: 100 μm) and the diamond single crystal substrate could be separated by electric discharge machining. The obtained insulating diamond layer was confirmed to be a single crystal by the electron diffraction method, and the half width of the rocking curve of the (400) plane by the double crystal X-ray diffraction method was good at 48 seconds.

(Example 5)
In this example, a natural IIa diamond single crystal (4 × 4 × 0.3 mm) was prepared. The plane orientation of the main surface was {100}. On this, an insulating diamond layer of 120 μm was formed by microwave plasma CVD using a methane 2% -hydrogen system.

After the growth surface was flattened by mechanical polishing, hydrogen ions were implanted from the growth surface. The injection energy was 5 MeV, and the injection amount was 1.5 × 10 ¹⁷ ions / cm ² . The implantation profile in the depth direction is as shown in FIG. 3. At the interface of the insulating diamond / single crystal substrate, a thickness of about 10 μm is 5 × 10 ¹⁸ pieces / cm ³ or more, and a maximum of 2 × 10 ²⁰ pieces / cm ³ . It becomes the injection amount. As a result of evaluating the outermost surface by the electron diffraction method, it was confirmed to be a single crystal. The sample thus obtained was subjected to the following electrochemical etching.

This injection layer exhibited electrical conductivity. An aqueous solution in which sodium sulfate was dissolved at a concentration of 0.2 mol / liter was used as the electrolyte. The above sample was set as a working electrode, and a potential of +30 V was applied to the working electrode using a silver-silver chloride electrode as a reference electrode. The working electrode connected the electrode to the injection layer (conductive), and the back surface of the substrate was protected with a resin. Then, it was confirmed that a large amount of oxygen and carbon dioxide was generated from the exposed portion of the side injection layer. The flowing current was about 800 A / cm ² per unit area where the injection layer was exposed.

  When the side surface was confirmed after the treatment for 3 hours, etching of the side surface of the injection layer proceeded to the entire surface, and the insulating diamond layer and the single crystal substrate could be separated. The injection layer partially remained on the separated surface, but could be removed by simple machining, and the single crystal substrate could be recycled.

(Example 6)
In this example, a natural IIa diamond single crystal (4 × 4 × 0.3 mm) was prepared. The plane orientation of the main surface was {100}. On this, an insulating diamond layer of 120 μm was formed by microwave plasma CVD using a methane 2% -hydrogen system.

After the growth surface was flattened by mechanical polishing, hydrogen ions were implanted from the growth surface. The injection energy was 5 MeV, and the injection amount was 1.5 × 10 ¹⁷ ions / cm ² . The implantation profile in the depth direction is as shown in FIG. 3. At the interface of the insulating diamond / single crystal substrate, a thickness of about 10 μm is 5 × 10 ¹⁸ pieces / cm ³ or more, and a maximum of 2 × 10 ²⁰ pieces / cm ³ . It becomes the injection amount.

This injection layer exhibited electrical conductivity. As an electrolyte, acetic acid was further mixed at a concentration of 1 mol / liter with an aqueous solution dissolved at a concentration of 0.25 mol / liter of sodium sulfate. The above sample was set as a working electrode, and a potential of +20 V was applied to the working electrode using a silver-silver chloride electrode as a reference electrode. The working electrode was connected to the injection layer and the back surface of the substrate was protected with a resin. Then, it was confirmed that a large amount of oxygen and carbon dioxide was generated from the exposed portion of the side injection layer. The flowing current was about 350 A / cm ² per unit area of the exposed portion of the injection layer.

  When the side surface was confirmed after the treatment for 2 hours, the etching on the side surface of the injection layer proceeded to the entire surface, and the insulating diamond layer and the single crystal substrate could be separated. The injection layer partially remained on the separated surface, but could be removed by simple machining, and the single crystal substrate could be recycled. The obtained insulating diamond single crystal had a favorable half-value width of the rocking curve of the (400) plane by a double crystal X-ray diffraction method of 44 seconds.

4 is a diagram showing a laminated structure of insulating diamond / B-doped diamond obtained in Example 2. FIG. 4 is a view showing a laminated structure of insulating diamond / B-doped diamond obtained in Example 3. FIG. It is the graph which showed the implantation profile of the depth direction of the ion implantation in Examples 4-6.

Claims (9)

A step of growing a semiconductor diamond layer on the diamond substrate by vapor phase synthesis;
A step of growing an insulating diamond layer thereon by vapor phase synthesis;
A method for producing diamond, comprising: a step of separating the insulating diamond layer and the diamond substrate by etching the semiconductor diamond layer by an electrochemical technique. A step of alternately laminating a plurality of semiconductor diamond layers and insulating diamond layers on a diamond substrate in the order of a semiconductor diamond layer and an insulating diamond layer by vapor phase synthesis;
A method for producing diamond, comprising a step of separating the plurality of insulating diamond layers and the diamond substrate by etching the plurality of semiconductor diamond layers by an electrochemical technique.   3. The method for producing diamond according to claim 1, wherein at least one of the diamond substrate, the semiconductor diamond layer, and the insulating diamond layer is single crystal diamond.   3. The method for producing diamond according to claim 1, wherein the etching by an electrochemical method is a method of etching by immersing diamond in an electrolyte aqueous solution and applying an electric potential to the electrode. And an organic acid or an alcohol is present in the electrolyte aqueous solution. A step of growing insulating diamond on the diamond substrate by vapor phase synthesis;
Ion implantation is performed so that an implantation layer having a maximum atomic concentration of 5 × 10 ¹⁸ atoms / cm ³ or more and 2 × 10 ²¹ atoms / cm ³ or less is formed immediately above the diamond substrate from the surface of the insulating diamond. Implanting ions of the atoms by the method,
A method for producing diamond, comprising a step of subjecting the injection layer to electrical discharge machining to separate the diamond substrate and the insulating diamond layer. A step of growing insulating diamond on the diamond substrate by vapor phase synthesis;
Ion implantation is performed so that an implantation layer having a maximum atomic concentration of 5 × 10 ¹⁸ atoms / cm ³ or more and 2 × 10 ²¹ atoms / cm ³ or less is formed immediately above the diamond substrate from the surface of the insulating diamond. Implanting ions of the atoms by the method,
A method for producing diamond, comprising a step of separating the diamond substrate and the insulating diamond layer by etching the injection layer by an electrochemical technique.   7. The method for producing diamond according to claim 5, wherein the ions to be implanted are ions selected from carbon, argon, helium, hydrogen, silicon, germanium, and tin. .   8. The method for producing diamond according to claim 5, wherein at least one of the diamond substrate and the insulating diamond layer is single crystal diamond. 7. The method for producing diamond according to claim 6, wherein the etching by an electrochemical method is performed by immersing diamond in an electrolyte aqueous solution and applying an electric potential to the electrode, and the material to be etched is disposed on the anode. And an organic acid or an alcohol is present in the aqueous electrolyte solution.

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