JPH07148426A - Synthetic diamond, manufacture of the same, and method for measuring strain of diamond - Google Patents

Abstract

PURPOSE:To reduce impurities, strain, and crystal defects, to prevent troubles such as breaking and cracking during pressurization, and to enable precise, quantitative measurement of strain by synthesizing diamond which has nitrogen and boron contents of specified values or less and reduced strain. CONSTITUTION:In order to reduce defects and strain in crystals, a nitrogen getter including metal such as Ti and Zr which are highly reactive with nitrogen and do not hinder the crystal growth of diamond is added to raw material and solvent metal such as Fe and Co in an amount of 0.1-5wt.% of the solvent metal to make the nitrogen content 10ppm or less, preferably 0.1ppm or less. High purity diamond powder having a boron content of 1ppm or less, preferably 0.1ppm or less, or more preferably high purity graphite which is treated with a halogen to eliminate boron almost completely is used as a carbon source. When monocrystalline diamond is synthesized by a temperature difference method, colorless, transparent synthetic diamond is obtained which has reduced impurities, crystal defects, strain, etc., and high crystallinity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an optical component, a dispersive crystal, a monochromator, a laser window material, a window material for synchrotron radiation or radiation, an anvil, a colorless and transparent impurity and a crystal defect used for decorative purposes and semiconductor substrates. The present invention relates to a synthetic diamond having a high degree of purity and good crystallinity with less distortion, a method for producing the same, and a method for measuring the distortion of diamond.

[0002]

2. Description of the Related Art Diamond has high hardness, high strength, excellent thermal conductivity, corrosion resistance, and good light transmittance. From this, the diamond crystal is a heat sink, wire drawing die,
It is used in a wide range of applications such as precision machining tools, optical parts, laser windows, and anvils for generating ultra-high pressure. Most naturally occurring diamonds are called type Ia and contain about 1000 ppm of nitrogen. Since nitrogen in the natural diamond is distributed in the crystal in an aggregated form, crystal defects and internal strain are large, and the nitrogen absorbs light in the infrared region. Also, due to the rough stones, the variation is large.
Therefore, the applicable applications have been limited to heat sinks and tools. A high-purity natural diamond having nitrogen impurities of several ppm or less is called type IIa, and such a diamond is rare, about 2% of the total amount of natural production. Natural type IIa diamond has few impurities,
Since it is colorless and transparent and has excellent light transmission properties, it is used for decorative purposes, optical parts, laser window materials and the like. However, reflecting the fact that it has undergone a complicated growth process inside the earth, many defects and strains remain inside the crystal.
In terms of strain, it is more than synthetic diamond containing nitrogen. In addition, natural type IIa has a small amount of production and is extremely expensive, and there is a problem in obtaining it.

A normal diamond artificially synthesized under ultrahigh pressure and high temperature is called type Ib and contains several hundred ppm of nitrogen. Since this nitrogen is contained in the diamond crystal as an isolated substitution type impurity, the crystal exhibits a yellow color and is of little value for decoration. Further, the concentration of nitrogen is extremely different depending on the growth sector, and there is a large unevenness in the distribution of nitrogen inside the crystal. Therefore, there are many distortions in the crystal. On the other hand, it is known that by adding a nitrogen getter such as Al to a solvent metal at the time of diamond synthesis, nitrogen in the synthesized diamond can be removed to about several ppm and a synthetic IIa type diamond can be obtained. However, when the nitrogen getter is added to the solvent metal, it is usually easy for a large amount of inclusions to be incorporated into the crystal, and the production yield of good-quality crystals is greatly reduced. For this reason, the conventional synthetic type IIa diamond has a higher manufacturing cost than the natural type IIa diamond. Also, removal of nitrogen in synthetic diamond is 1p
The limit was about pm, and the evaluation for decoration was about H to J on the GIA scale (JP-A-52-88289). As described above, in the conventional synthetic diamond, a crystal containing almost no nitrogen and containing neither inclusions nor internal defects was not known.

The present inventors have used at least one element selected from the group IVa and group Va elements having a high nitrogen removal efficiency as a nitrogen getter, and at the same time, to prevent inclusions from being incorporated into the crystal, a group IVa element By adding a substance that suppresses the formation of carbides, a substance that diffuses carbides, or a substance that improves the activity of carbon in the solvent metal to the solvent metal, inclusions with a nitrogen content of 0.1 ppm or less can be eliminated.
Successfully manufactured IIa type synthetic diamond. However, the crystal still contained several ppm of boron, so that light was absorbed by boron in the infrared region, and there were some distortions and defects in the crystal.

[0005]

As described above, natural diamond has many defects and large strains inside the crystal. Although natural type IIa diamond has few impurities,
It is not good in terms of crystallinity such as defects and distortion. Therefore, cracks are likely to occur during processing, and when used in fields requiring strength as diamond, such as an ultra-high pressure generating anvil, FT-IR compression cell, and laser window material, in some cases, it immediately breaks. There was a problem of being lost. Further, since a monochromator, a semiconductor substrate and the like are required to have a high degree of crystallinity, they cannot be applied to this field. On the other hand, although artificially synthesized type IIa diamond is far superior in crystallinity to natural ones, it cannot be said to be sufficient, and the processing yield is low, and its mechanical strength is lower than the original characteristics of diamond. However, there is a problem that it cannot be applied to applications requiring crystallinity such as a monochromator and a semiconductor substrate.
In addition, it is several ppm for conventional synthetic type IIa diamond crystals.
Since boron is contained therein, light is absorbed by boron in the infrared region, and there is a problem in application as an optical component.
There were also some distortions and defects in the crystal. That is, in the synthesis of diamond by the temperature difference method, diamond powder is used as a carbon source, but commercially available synthetic diamond powder contains 10 to 1000 ppm of boron,
Natural diamond powder also contains tens to hundreds of ppm of boron and has a large variation. When diamond is synthesized using such a carbon source, it is several ppm to several tens of p in the crystal.
It contains pm boron and the crystals are blue in color. Therefore, there is absorption by boron in the infrared region and the ultraviolet to visible region, which is not preferable as an optical component. In addition, the concentration of boron is extremely different depending on the crystal growth sector,
There is a large unevenness in the distribution of boron inside the crystal. This point is considered to be one of the reasons for poor crystallinity.

[0006] By the way, the measurement of the strain of diamond has conventionally been performed by visual measurement using a polarized light transmission microscope, but this method is not very precise in terms of quantification. Further, Si (004) or Ge (0) which is often used as the first crystal in the X-ray diffraction method of the two-crystal method.
A method for measuring the strain of diamond using 04) has also been proposed, but the half-width of the rocking curve is extremely wide (for example, about 60 seconds) because the crystal plane spacing used for diffraction is not the same as that of diamond, And it did not lead to quantitative distortion evaluation. In view of the above situation, the present invention is intended to provide a synthetic diamond having high purity and less impurities, crystal defects, strain, etc., a method for producing the same, and a method for measuring strain of the synthetic diamond.

[0007]

Means for Solving the Problems The present invention for solving the above-mentioned problems includes (1) a nitrogen content of 10 ppm or less, preferably 0.1 ppm or less, and a boron content of 1 ppm or less, preferably 0.1 ppm or less. (2) X-ray diffraction measured by CuKα ray in a (004) plane parallel arrangement, using a diamond crystal as the first crystal in X-ray diffraction by the two-crystal method. A synthetic diamond with little distortion characterized by a half-width of the line diffraction rocking curve of 6 seconds or less, (3) 13 Raman spectroscopic spectra of diamond measured by a Raman spectroscopic analyzer having a resolution of 1 cm ^-1 or less.
The full width at half maximum of the peak at 32 to 1333 cm ^-1 is 2.3.
The present invention provides a synthetic diamond with a low strain, which is characterized in that it is not more than cm ^-1 , preferably not more than 2 cm ^-1 . The present invention also relates to a synthetic diamond having a small strain, which has a combination of at least two of the features (1) to (3). Further, the present invention also provides a method for producing the above-mentioned synthetic diamond having less strain, and the production method of the present invention is a carbon source having a boron content of 10 ppm or less in the method for synthesizing a diamond single crystal by a temperature difference method. And boron content is 1
It is characterized in that a solvent metal of ppm or less is used, and a nitrogen getter is added to the solvent metal to synthesize a diamond having a small strain having any one of the characteristics (1) to (3). In the present invention, boron is removed by halogenation as the carbon source so that the boron content is 1 p
It is particularly preferable to use graphite of pm or less. Further, in the present invention, the nitrogen getter is IV of the periodic table.
It is particularly preferable that it is at least one selected from the group a and group Va elements. Further, in the present invention, it is particularly preferable that the solvent metal is added with an element that suppresses the formation of carbide of an element selected from the IVa group and the Va group elements of the periodic table. Further, in the present invention, it is particularly preferable to dispose a buffer material between the solvent metal and the seed surface for stabilizing the initial growth of crystals. Further, in the present invention, after synthesizing diamond under an ultrahigh pressure and high temperature by a temperature difference method, when the temperature and pressure of the sample part are lowered to room temperature and normal pressure and depressurized, the temperature of the sample part is 300 to
Completion of depressurization at 1000 ° C. is also mentioned as a particularly preferred embodiment. Further, the present invention provides a method for measuring the strain of synthetic diamond, the first of which is to measure the X-ray diffraction rocking curve using a diamond crystal as the first crystal and to determine the strain in the synthetic diamond based on the half width. Characterized by evaluation. The second is characterized in that the X-ray diffraction rocking curve is measured by the four-crystal method using Si, Ge or diamond crystals and the strain in the synthetic diamond is evaluated based on the half-value width. Third, the Raman spectrum of 1332 cm
^A method for measuring strain of a synthetic diamond, which comprises measuring a peak of ^-1 and evaluating a strain in the synthetic diamond based on a half width thereof.

[0008]

In order to solve the above problems, the present inventors evaluated the crystallinity of various diamonds by various means. During the research, an X-ray diffraction method using a very high purity and low strain synthetic diamond developed by the present invention as a first crystal could be developed. According to this method, the strain can be measured very accurately and quantitatively. The strain in the diamond crystal is the full width at half maximum of the X-ray diffraction rocking curve measured using the diamond crystal as the first crystal, the full width at half maximum of the X-ray diffraction rocking curve measured by the four-crystal method, or the Raman spectroscopic spectrum of 1332-. A new finding was obtained that the peak half width of 1333 cm ⁻¹ can be evaluated accurately and quantitatively. As a result of examination by this method, it was found that in natural diamond, both Ib type and IIa type have considerably large strains, and synthetic diamond has much less strain. Further, it has been found that even synthetic diamonds containing impurities such as nitrogen and boron to a certain extent have a large amount of strain, and when the amount of these impurities is 0.1 ppm or less, the strain in the diamond crystal is almost eliminated. . That is, in the X-ray diffraction by the two-crystal method, a diamond crystal is used as the first crystal, and the rocking curve of the X-ray diffraction measured by CuKα ray in the (004) plane parallel arrangement has a half value width of 6 seconds or less, or the Raman when the half-value width of the peak of 1332～1333Cm ^-1 of the spectrum is 2 cm ^-1 or less, the strain in the crystal was found that almost no.

In the production method of the present invention, in order to reduce internal defects and distortion in the crystal, first, boron impurities in the raw material and the solvent metal are reduced as much as possible, and the nitrogen getter is added to the solvent metal weight of 0. Add 1-5% by weight,
The nitrogen content and the boron content in the crystal are each 0.1 p
pm or less. Examples of the solvent metal include Fe and C
Examples thereof include metals such as o, Ni, Mn, and Cr, or alloys containing these metals. As the nitrogen getter, a substance having a high reactivity with nitrogen that does not inhibit the crystal growth of diamond is used. For example, at least an element selected from Group IVa of the periodic table and Va elements such as Ti, Zr, and Hf. Examples include metals and alloys of one or more kinds. As the carbon source of the present invention, it is preferable to use high-purity diamond powder having a boron content of 10 ppm or less, and it is more effective to use a high-purity graphite that has been subjected to a halogen treatment to remove most of the boron amount. is there. At the same time, elements that suppress the formation of carbides of elements selected from the IVa group and Va group elements, such as Cu, Ag,
The element selected from Au and the like is 0.1 to 20 with respect to the solvent metal.
Addition by weight% is also effective.

Further, Al, Ni, Cu, Zn, and G are formed between the seed surface and the solvent metal in order to stabilize the growth state in the initial stage of the crystal.
A buffer material made of an element selected from the group consisting of a, Ag, Cd, In, Sn, Au, Tl and Pb, for example, A
It is very effective to dispose a thin plate such as a 1 plate or a Cu plate having a thickness of 0.01 mm to 0.5 mm. By adopting such means, distortion due to inclusion of inclusions,
It is possible to reduce crystal defects and strain in the crystal due to unstable growth in the initial stage of crystal growth. Furthermore, after synthesizing diamond under the superhigh-pressure and high-temperature conditions generally used in the technical field of diamond synthesis by the temperature difference method, the internal temperature is 300
~ 1000 ° C, preferably 400-800 ° C,
More preferably, releasing the pressure at a temperature of 500 to 600 ° C. is more effective, and the strain due to stress does not remain in the crystal.

The embodiments of the present invention will be summarized below. (1) The method for producing a synthetic diamond with less strain according to any one of claims 15 to 20, wherein the nitrogen getter is added in an amount of 0.1 to 5% by weight with respect to the solvent. (2) The method for producing a synthetic diamond with low strain according to any one of claims 15 to 20, wherein the solvent metal is at least one selected from metals of Fe, Co, Ni, Mn and Cr or alloys thereof. (3) A method for producing a synthetic diamond, which is a combination of any one of claims 15 to 20 with the above (1) and (2). (4) The synthetic diamond with low strain according to claim 18, wherein 0.1 to 20 wt% of an element that suppresses the formation of carbides of elements selected from the IVa group and the Va group elements of the periodic table is added to the solvent metal. Production method. (5) The elements that suppress the formation of carbides of the elements selected from the IVa group and Va group elements of the periodic table are Cu, Ag and A.
The method for producing a synthetic diamond with a small strain described in (4) above, which is selected from u. (6) The buffer material is Al, Ni, Cu, Zn, Ga, Ag,
20. The method for producing a synthetic diamond with less strain according to claim 19, which is a thin plate made of an element selected from the group consisting of Cd, In, Sn, Au, Tl and Pb. (7) The method for producing a synthetic diamond with a small strain described in (6) above, wherein the thin plate has a thickness of 0.01 to 0.5 mm. (8) Any one of claims 15 to 20 and the above (4) to.
A method for producing a synthetic diamond, which is a combination of (7). (9) The completion of depressurization is performed at 500 to 600 ° C.
20. A method for producing a synthetic diamond with low strain according to any one of 19 to 19 above.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. [Embodiment 1] FIG. 1 shows the sample chamber structure for diamond synthesis used in the following embodiments and comparative examples. Carbon source here (1)
As the material, a synthetic diamond powder having a boron content of 3 ppm was used. Boron content of solvent metal (2) is 1ppm
The following Fe and Co are used, and the solvent metal composition is Fe / Co =
It was set to 60/40 (weight ratio). To this solvent metal, 1.5% by weight of Ti (based on the weight of the solvent metal) was added as a nitrogen getter, and 1% by weight (based on the weight of the solvent metal) of Cu was further added. As the seed crystal (3), a diamond crystal having a size of 500 μm was used. Then, the carbon source (1) and the seed crystal (3) were set in the heating graphite heater (5) so that there was a temperature difference of about 30 ° C. This was held at a pressure of 5.5 Pa and a temperature of 1300 ° C. for 70 hours using an ultrahigh pressure generator to grow diamond on the seed crystal. Then, the temperature was first lowered to room temperature and then depressurized to take out the synthesized diamond. As a result, 0.7-
0.9 carat colorless and transparent, with high quality with almost no inclusions
A type IIa diamond crystal was obtained. As a result of measuring the amount of nitrogen in the crystal by ESR, all were 0.1 ppm or less. When UV-visible and infrared spectra were measured,
No absorption by nitrogen or boron other than absorption by diamond itself was observed. The polarized light transmission image of the obtained diamond was observed with a polarized light transmission microscope, and the distortion was evaluated.
It turns out that there is almost no distortion. Further, the half width of the rocking curve of the X-ray diffraction of CuKα by the double crystal method in which the synthetic diamond crystal (004) plane was used as the first crystal and was arranged in parallel was measured and found to be 5.8 seconds. Also,
The Raman spectroscopic spectrum was measured with a double monochromator Raman spectroscope with a resolution of 0.5 cm ⁻¹ , and 1332 cm
Was determined the full width at half maximum of ^-1, it was 1.8cm ^-1.

[Examples 2 to 4, Comparative Example 1] Carbon source (1)
A synthetic diamond powder containing 23 ppm of boron was used, and the amounts of Ti and Cu added to the solvent metal (both with respect to the weight of the solvent metal) were changed as follows. Example 2: Ti addition amount 1.5% by weight, Cu addition amount 2% by weight Example 3: Ti addition amount 1.0% by weight, Cu addition amount 1% by weight Example 4: Ti addition amount 0.5% by weight , Cu addition amount 1% by weight Comparative Example 1: No Ti and Cu were added, and diamond crystals were synthesized under the same conditions as in Example 1 except for the above conditions. Each of the four types of crystals thus obtained, and six naturally-occurring type IIa diamonds and six naturally-occurring type Ib diamonds, nitrogen impurities, boron impurities, rocking curve half-widths, Raman peak half-widths,
And, the distortion evaluation by observation of the polarized light transmission image was measured and evaluated in the same manner as in Example 1. The results are shown in Table 1 together with the results of Example 1.

[0014]

[Table 1]

[Embodiment 5] Between the solvent metal and the seed crystal, a thickness of 0.
In the same manner as in Example 1 except that a 05 mm Al plate is arranged.
A type IIa diamond was synthesized. As a result, the rocking curve half-width was 5.6 seconds, and the Raman spectroscopic spectrum peak half-width was 1.6 cm ⁻¹ , and the crystallinity was further improved.

Example 6 After synthesizing diamond, the temperature is lowered and the pressure is reduced at the same time, and the internal temperature is 500 ° C.
In the same manner as in Example 1 except that the depressurization was completed.
A type IIa diamond was synthesized. As a result, the rocking curve full width at half maximum was 5.7 seconds, the full width at half maximum of the Raman spectroscopic spectrum peak was 1.6 cm ⁻¹ , and crystallinity was improved.

In the above Examples and Comparative Examples, an example was shown in which the (004) plane of diamond was used as the first crystal for X-ray diffraction and arranged in parallel, but the strain measurement method by X-ray diffraction of the present invention is Other planes such as the (111) plane of diamond may be used, and it is effective to use, for example, an asymmetrical arrangement other than the parallel arrangement.

[0018]

As described above, the synthetic diamond of the present invention has few impurities, few distortions, and few crystal defects, so that defects such as cracks and cracks during pressurization are reduced.
When it is used as a diamond anvil for generating ultra-high pressure and a diamond anvil for FT-IR, its life and stability are significantly improved. Furthermore, it is also very effective when applied to applications requiring high crystallinity of diamond, such as monochromators, radiant light or radiation window materials, and semiconductor substrates. Further, the above-described high-quality synthetic diamond can be realized by the manufacturing method of the present invention. Furthermore, the strain measuring method of the synthetic diamond of the present invention enables more precise and quantitative strain measurement than the conventional method, and is very advantageous.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a structure of a sample chamber in diamond synthesis of the present invention.

[Explanation of symbols]

 1 Carbon source 2 Solvent metal 3 Seed crystal 4 Insulator 5 Graphite heater 6 Pressure medium

Claims (24)

[Claims] 1. A synthetic diamond with a low strain, which has a nitrogen content of 10 ppm or less and a boron content of 1 ppm or less. 2. In the X-ray diffraction by the two-crystal method, a diamond crystal is used as the first crystal, and the half-width of the X-ray diffraction rocking curve is 10 seconds or less when measured by CuKα ray in a (004) plane parallel arrangement. A synthetic diamond with little distortion characterized by: Strain wherein resolution FWHM of the peak at 1332～1333Cm ^-1 of Raman spectrum of diamond, measured in 1 cm ^-1 or less of the Raman spectroscopic analysis apparatus is characterized in that it is 2.3 cm ^-1 or less Low synthetic diamond. 4. A nitrogen content of 10 ppm or less and a boron content of 1 ppm or less, and in X-ray diffraction by a two-crystal method, a diamond crystal is used as a first crystal and a (004) plane parallel arrangement is used. , A synthetic diamond with little distortion, characterized in that the full width at half maximum of the X-ray diffraction rocking curve measured by CuKα ray is 10 seconds or less. 5. A nitrogen content of 10 ppm or less, a boron content of 1 ppm or less, and a resolution of 1c.
small synthetic diamond distortion, wherein a half-value width of the peak at 1332～1333Cm ^-1 of Raman spectrum of diamond, measured in m ^-1 or less of the Raman spectrometer is 2.3 cm ^-1 or less. 6. A synthetic diamond having a nitrogen content of 10 ppm or less and a boron content of 1 ppm or less, wherein a diamond crystal is used as a first crystal in X-ray diffraction by a two-crystal method, and (004) plane parallel Arrangement, CuK
half-width of X-ray diffraction rocking curve as measured by α-rays is 10 seconds or less, and, in 1332～1333Cm ^-1 of Raman spectrum of diamond resolution was measured at 1 cm ^-1 or less of the Raman spectroscopic analysis device A synthetic diamond with little distortion, which is characterized by having a peak half-width of 2.3 cm ^-1 or less. 7. In the X-ray diffraction by the two-crystal method, a diamond crystal is used as the first crystal, the half-width of the X-ray diffraction rocking curve is 10 seconds or less when measured by CuKα ray in a (004) plane parallel arrangement. And the Raman spectroscopic spectrum of the diamond measured with a Raman spectroscopic analyzer having a resolution of 1 cm ^-1 or less is 1332 to 1333 cm.
-Synthetic diamond with little distortion, characterized in that the half-value width of the peak at ^-1 is 2.3 cm ^-1 or less. 8. A synthetic diamond having a low strain, which has a nitrogen content of 0.1 ppm or less and a boron content of 0.1 ppm or less. 9. In the X-ray diffraction by the two-crystal method, a diamond crystal is used as the first crystal, and the half-width of the X-ray diffraction rocking curve is 6 seconds or less when measured by CuKα ray in a (004) plane parallel arrangement. A synthetic diamond with little distortion characterized by: Less distortion, characterized in that 10. A resolution FWHM of the peak at 1332～1333Cm ^-1 of Raman spectrum of diamond, measured in 1 cm ^-1 or less of the Raman spectrometer is 2 cm ^-1 or less Synthetic diamond. 11. A nitrogen crystal having a nitrogen content of 0.1 ppm or less and a boron content of 0.1 ppm or less, and using a diamond crystal as a first crystal in X-ray diffraction by a two-crystal method, (004) A synthetic diamond with little distortion, characterized in that the half-width of the X-ray diffraction rocking curve when measured by CuKα ray in a plane parallel arrangement is 6 seconds or less. 12. A Raman spectroscopic spectrum 1332 of diamond measured with a Raman spectroscopic analyzer having a nitrogen content of 0.1 ppm or less, a boron content of 0.1 ppm or less, and a resolution of 1 cm ^-1 or less. ~ 1333
A synthetic diamond with little distortion, which has a half-value width of a peak at cm ^-1 of 2 cm ^-1 or less. 13. A synthetic diamond having a nitrogen content of 0.1 ppm or less and a boron content of 0.1 ppm or less, wherein a diamond crystal is used as a first crystal in X-ray diffraction by a two-crystal method, 004) In the plane parallel arrangement,
The half width of the X-ray diffraction rocking curve measured by CuKα ray is 6 seconds or less, and the resolution is 1 cm.
Small synthetic diamond distortion, wherein a half-value width of the peak is 2 cm ^-1 or less at ^-1 or less 1332～1333Cm ^-1 of Raman spectrum of diamond, measured by Raman spectroscopy device. 14. In the X-ray diffraction by the two-crystal method, a diamond crystal is used as the first crystal, the half-width of the X-ray diffraction rocking curve is 6 seconds or less when measured by CuKα ray in a (004) plane parallel arrangement. And the Raman spectroscopic spectrum of the diamond measured with a Raman spectroscopic analyzer having a resolution of 1 cm ^-1 or less is 1332 to 1333 cm.
^-Synthetic diamond with little distortion, characterized in that the full width at half maximum of the peak at ^-1 is 2 cm ^-1 or less. 15. A method for synthesizing a diamond single crystal by a temperature difference method, wherein a carbon source having a boron content of 10 ppm or less and a solvent metal having a boron content of 1 ppm or less are used, and a nitrogen getter is added to the solvent metal. 15. The method for producing a synthetic diamond with a small strain according to claim 8, wherein the diamond is synthesized by means of a method. 16. The method for producing a synthetic diamond with low strain according to claim 15, wherein graphite having a boron content of 1 ppm or less by removing boron by halogenation is used as the carbon source. 17. The production of synthetic diamond with low strain according to claim 15 or 16, characterized in that the nitrogen getter is at least one element selected from Group IVa and Group Va elements of the periodic table. Method. 18. The method according to claim 15, wherein the solvent metal is added with an element that suppresses the formation of carbide of an element selected from the IVa group and Va group elements of the periodic table. 5. The method for producing a synthetic diamond with little distortion according to any one of 1. 19. The strain according to claim 15, wherein a buffering material for stabilizing the initial growth of crystals is provided between the solvent metal and the seed surface. Manufacturing method of few synthetic diamonds. 20. When the temperature and pressure of the sample part are decreased to room temperature and normal pressure after synthesizing diamond under the super high pressure and high temperature by the temperature difference method, and the pressure of the sample part is 300 to 300 ° C.
20. The method for producing a synthetic diamond with less strain according to claim 15, wherein depressurization is completed at 1000 ° C. 21. As the first crystal, a rocking curve is measured by the two-crystal method using a diamond crystal having the same diffraction angle within 10 seconds as the Bragg angle of the diffraction surface of the diamond crystal used for measurement, A method for measuring strain of synthetic diamond, which comprises evaluating strain in synthetic diamond based on the half width. 22. A method for measuring strain of synthetic diamond, wherein the same diffraction surface as that of the diamond crystal to be measured is used as the diffraction surface of the first crystal. 23. A rocking curve of a synthetic diamond is measured by a four-crystal method using a crystal of Si, Ge or diamond, and the strain in the synthetic diamond is evaluated based on the half width thereof. Strain measurement method. 24. Raman spectroscopy spectrum 1332-1
A strain measuring method for synthetic diamond, comprising measuring a spectrum peak due to LO phonons near 333 cm ⁻¹ and evaluating strain in the synthetic diamond based on the half width.