Monocrystalline diamond substrate

Abstract

A single crystal diamond substrate includes a first main face and a second main face opposite the first main face, each of the first main face and the second main face including an area of 0.25 mm 2 the above continuous single growth sector, an average value cl of an atomic number-based content of nitrogen in the growth sector is 0.01 ppm or more and 50 ppm or less.

Description

Technical Field

[0001] This disclosure relates to single-crystal diamond substrates. This application claims priority to Japanese Application No. 2024-054171, filed on March 28, 2024, and incorporates the entire contents of that Japanese application. Background Technology

[0002] In recent years, the use of diamond in magnetic sensors has attracted much attention as a new application of diamond. Nitrogen is added to the diamond used in magnetic sensors via substitution (Patent Document 1). For example, the diamond used in magnetic sensors is fabricated from a single-crystal diamond substrate.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2022 / 210566 Summary of the Invention

[0006] The single-crystal diamond substrate disclosed herein includes a first main surface and a second main surface opposite to the first main surface. Each of the first and second main surfaces has an area of ​​0.25 mm². 2 The above refers to continuous, single growth sectors. The average nitrogen content (c1) in each growth sector, based on atomic number, is between 0.01 ppm and 50 ppm. Attached Figure Description

[0007] Figure 1 This is an example of a side view of the single-crystal diamond substrate involved in Embodiment 1.

[0008] Figure 2 This is an example of a top view of the single-crystal diamond substrate involved in Embodiment 1.

[0009] Figure 3 This is a diagram showing a single-crystal diamond grown from a single-crystal diamond seed substrate.

[0010] Figure 4 It shows from Figure 3 A diagram showing the first principal surface 1a of the single-crystal diamond substrate cut out at the location indicated by reference numeral P1 in the attached figure.

[0011] Figure 5 It shows from Figure 3 A diagram showing the second principal surface 1b of a single-crystal diamond substrate cut out at the location indicated by reference numeral P1 in the attached figure.

[0012] Figure 6 This is a diagram illustrating the method for determining the nitrogen content of a single-crystal diamond substrate.

[0013] Figure 7 This is a cross-sectional view of the single-crystal diamond seed substrate used in Embodiment 2.

[0014] Figure 8 This is a schematic diagram illustrating the configuration of the sample chamber used in the temperature difference method under high temperature and high pressure.

[0015] Figure 9 This diagram illustrates the relationship between the cut position of a single-crystal diamond substrate and the orientation of the main surface.

[0016] Figure 10 This diagram illustrates the relationship between the cut position of a single-crystal diamond substrate and the orientation of the main surface.

[0017] Figure 11 This is a diagram used to illustrate the cut-out positions of a single-crystal diamond substrate. Detailed Implementation

[0018] Single-crystal diamond substrates can be cut from single-crystal diamond formed on a single-crystal diamond seed substrate (hereinafter also referred to as "seed substrate"). In the synthesis of single-crystal diamond, the seed substrate has a significant impact on the crystallinity of the single-crystal diamond grown on it. For example, cracks can form inside a single-crystal diamond grown starting from a corner of the seed substrate. When cutting a single-crystal diamond substrate from a cracked single-crystal diamond, the single-crystal diamond substrate will fracture due to the cracks. Even if the single-crystal diamond substrate does not fracture, the growth sector will be broken due to the internal cracks, and the area of ​​a single growth sector will be less than 0.25 mm². 2 .

[0019] One of the objectives of this disclosure is to provide a single-crystal diamond substrate for high-sensitivity magnetic sensors that can achieve the same quality with high yield.

[0020] The single-crystal diamond substrate disclosed herein enables the production of high-sensitivity magnetic sensor diamonds of the same quality with high yield.

[0021] First, embodiments of this disclosure will be described.

[0022] (1) The single-crystal diamond substrate involved in the embodiments of this disclosure is a single-crystal diamond substrate including a first main surface and a second main surface opposite to the first main surface, wherein the first main surface and the second main surface each have an area of ​​0.25 mm². 2 The above-mentioned continuous single growth sectors, wherein the average c1 of nitrogen content based on atomic number in the growth sector is above 0.01 ppm and below 50 ppm.

[0023] In the single-crystal diamond substrate of this disclosure, the continuous single growth sector on its main surface has a large area, and the growth sector has a nitrogen concentration suitable for high-sensitivity magnetic sensors. Therefore, from the single-crystal diamond substrate of this disclosure, diamonds for high-sensitivity magnetic sensors of the same quality can be obtained with high yield.

[0024] (2) In (1) above, the area of ​​the growth sector can also be 5 mm. 2 The above. Based on this, it is possible to obtain high-sensitivity magnetic sensor diamonds of the same quality from single-crystal diamond substrates with a higher yield.

[0025] (3) In (1) or (2) above, the orientation of the first principal surface and the second principal surface may also be a (lmn) surface that satisfies l+m+n≤8. Accordingly, in a single-crystal diamond substrate, it is possible to determine: a flat growth surface (a surface exhibiting ego-shape) formed by a temperature difference method under high temperature and high pressure, a crystal axis that is easy to determine the sensing direction, and an orientation of the surface used to achieve high-sensitivity sensing, etc. Therefore, in a magnetic sensor using diamond from a single-crystal diamond substrate, the magnetic direction required for sensing can be included.

[0026] (4) In any of (1) to (3) above, the orientation of the first main surface and the second main surface may also be (111) plane. Accordingly, in a magnetic sensor using diamond for magnetic sensors made from a single-crystal diamond substrate, the sensing magnetic direction can be easily aligned. <111> This can improve the magnetic sensitivity of the desired detection.

[0027] (5) In any of (1) to (3) above, the orientation of the first main surface and the second main surface may also be (100) plane. Accordingly, in a magnetic sensor using diamond for magnetic sensors made from a single-crystal diamond substrate, the sensing magnetic direction can be easily aligned. <100> This can improve the magnetic sensitivity of the desired detection.

[0028] (6) In any of (1) to (3) above, the orientation of the first main surface and the second main surface may be (110) plane. Accordingly, in a magnetic sensor using diamond for magnetic sensors made from a single-crystal diamond substrate, the sensing magnetic direction can be easily aligned. <110> This can improve the magnetic sensitivity of the desired detection.

[0029] (7) In any of (1) to (6) above, the total content of impurity elements other than nitrogen in the growth sector, based on atomic number, is lower than the content of nitrogen based on atomic number, and is 0.01 ppb or more and 5 ppm or less. Accordingly, in a magnetic sensor using diamond from a single-crystal diamond substrate, the noise of magnetic sensitivity caused by impurities is reduced, and the magnetic sensitivity can be improved.

[0030] (8) In any of (1) to (7) above, it may also be that, in the growth sector, the difference between the maximum value c2 of the nitrogen content based on the number of atoms and the average value c1 of the nitrogen content based on the number of atoms is less than 50% of the average value c1 by a percentage {(c2-c1) / c1}×100, and the difference between the average value c1 and the minimum value c3 of the nitrogen content based on the number of atoms is less than 50% of the average value c1 by a percentage {(c1-c3) / c1}×100.

[0031] Deviations in the nitrogen content (based on atomic number) within the growth sector are a major cause of noise in the magnetic sensitivity of magnetic sensors. When the average value c1, maximum value c2, and minimum value c3 of the nitrogen content (based on atomic number) meet the above conditions, the noise in the magnetic sensitivity is reduced and the magnetic sensitivity is improved in magnetic sensors using diamond from single-crystal diamond substrates.

[0032] [Details of the embodiments of this disclosure]

[0033] Hereinafter, details of embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following drawings, the same reference numerals denote the same or equivalent parts. In addition, for the sake of clarity and simplification of the drawings, dimensional relationships such as length, width, thickness, and depth may be appropriately changed, and do not necessarily represent actual dimensional relationships.

[0034] [Implementation Method 1: Single-crystal diamond substrate]

[0035] like Figure 1 and Figure 2 As shown, one embodiment of this disclosure (hereinafter also referred to as "Embodiment 1") involves a single-crystal diamond substrate 1 including a first main surface 1a and a second main surface 1b opposite to the first main surface 1a. The first main surface 1a and the second main surface 1b each have an area of ​​0.25 mm². 2 The above refers to continuous, single growth sectors. The average nitrogen content (c1) in each continuous, single growth sector, based on atomic number, is above 0.01 ppm and below 50 ppm.

[0036] In the single-crystal diamond substrate 1 of Embodiment 1, the continuous single growth sector in the main surface has a large area, and the growth sector has a nitrogen concentration suitable for a high-sensitivity magnetic sensor. Therefore, from the single-crystal diamond substrate 1 of Embodiment 1, diamonds for high-sensitivity magnetic sensors of the same quality can be obtained with a high yield.

[0037] <Area of ​​a continuous single growth sector>

[0038] The single-crystal diamond substrate 1 of Embodiment 1 of this disclosure is made of single-crystal diamond grown on a single-crystal diamond seed substrate (hereinafter also referred to as "seed substrate"). The single-crystal diamond includes growth sectors grown from crystal planes at specific orientations of the seed substrate. The growth sector grown from the (abc) plane (crystal plane) of the seed substrate is shown as the (abc) sector. Examples of growth sectors included in the single-crystal diamond include sector (100), sector (111), sector (113), and sector (115). For example, Figure 3 The single-crystal diamond 2 shown includes a (100) sector grown from the (100) facet of the seed substrate 5 and a (111) sector grown from the (111) facet of the seed substrate 5.

[0039] Figure 4 It shows from Figure 3 A diagram showing the first main surface 1a of the single-crystal diamond substrate cut out at the location indicated by reference numeral P1 in the attached figure. Figure 5 Showing from Figure 3 A diagram showing the second principal surface 1b of the single-crystal diamond substrate cut at the location indicated by reference numeral P1 in the attached drawing. (See attached drawing.) Figure 4 As shown, the first principal plane 1a consists only of consecutive (100) sectors. Figure 5 As shown, the second principal surface 1b consists of a continuous (100) sector and four (111) sectors. The four (111) sectors of the second principal surface 1b are grown from four different crystal planes of the seed substrate, therefore, as Figure 5 As shown, there is a boundary 20 in the (111) sector. Therefore, the four (111) sectors of the second principal surface 1b are not continuous. Thus, even if the principal surface contains multiple growth sectors of the same kind that are connected to each other, these multiple growth sectors do not belong to a continuous single growth sector when they are divided by the existence of a boundary.

[0040] In Embodiment 1, the first and second principal surfaces of the single-crystal diamond substrate each have an area of ​​0.25 mm². 2 The above describes a continuous, single growth sector. This improves the uniformity of the quality of the single-crystal diamond substrate, enabling the production of magnetic sensor diamonds of the same quality from the single-crystal diamond substrate with a high yield.

[0041] The area of ​​a single, continuous growth sector on each of the first and second principal surfaces of a single-crystal diamond substrate can be 0.25 mm². 2 Above and 400mm 2 The following can also be 5mm. 2 Above and 300mm 2 Below that, it can also be 7mm. 2 Above and 200mm 2 Below, or possibly 10mm 2 Above and 100mm 2 the following.

[0042] The fluorescence intensity of growth sectors grown from different crystal faces of the seed substrate varies due to differences in impurity concentration. The fluorescence distribution on the main face of a single-crystal diamond substrate can be observed using photoluminescence (PL) or cathodoluminescence (CL). By observing the fluorescence distribution, the boundaries of the growth sectors grown from different crystal faces of the seed substrate can be determined. Within each of the first and second main faces, the boundaries of different growth sectors are determined using PL or CL, and the area of ​​a single, continuous growth sector within each of the first and second main faces is measured.

[0043] PL is performed, for example, by using excitation light with a wavelength below 350 nm and adjusting the intensity of the excitation light so that the boundaries of the growth sector can be clearly observed. CL is performed, for example, by detecting the light emitted when an electron beam is irradiated onto a single-crystal diamond substrate under conditions of an accelerating voltage of 20 kV and a sample current of 20 nA.

[0044] <Nitrogen content of a continuous single growth sector>

[0045] Average nitrogen content c1

[0046] In the single-crystal diamond substrate of Embodiment 1, the average value c1 of the nitrogen content (hereinafter also referred to as "nitrogen content") in a continuous single growth sector, based on the number of atoms, is 0.01 ppm or more and 50 ppm or less. When the average value c1 of the nitrogen content is 0.01 ppm or more, the diamond for magnetic sensors from the single-crystal diamond substrate is suitable for high-sensitivity magnetic sensors. When the average value c1 of the nitrogen content is 50 ppm or less, the occurrence of crystal defects and strain that may be caused by nitrogen in the single-crystal diamond substrate can be suppressed. The average value c1 of the nitrogen content can be 0.1 ppm or more and 20 ppm or less, or 0.3 ppm or more and 10 ppm or less, or 0.5 ppm or more and 3 ppm or less.

[0047] The average nitrogen content c1 of continuous single growth sectors was determined and calculated by secondary ion mass spectrometry (SIMS). The analytical conditions are as follows.

[0048] Analysis Conditions

[0049] Primary ion type: Cs+

[0050] Primary acceleration voltage: 15kV

[0051] Determine the diameter of the light spot: 30mm

[0052] use Figure 6 The location for measuring nitrogen content in a continuous, single growth sector is described. Figure 6 In the attached diagram, reference numerals 3a, 3b, 3c, 3d, and 3e indicate the measurement locations, and are set as follows: The center of the largest inscribed circle C1 of the continuous, single growth sector of the first principal surface 1a of the single-crystal diamond substrate 1 is designated as 3a. The points dividing the circumference of the largest inscribed circle C1 into four parts are designated as 3b, 3c, 3d, and 3e, respectively.

[0053] The nitrogen content was measured by SIMS at the five measurement sites 3a, 3b, 3c, 3d, and 3e, and the average value was calculated. In this disclosure, this average value corresponds to the average nitrogen content c1 of a continuous single growth sector.

[0054] It has been confirmed that, within the same single-crystal diamond substrate, even when the nitrogen content is measured by changing the measurement sites 3b, 3c, 3d, and 3e on the circumference of the largest inscribed circle C1, the obtained nitrogen content is almost identical. Furthermore, the above measurement was performed on a continuous, single growth sector at a measurement site located on the first main surface. It has been confirmed that even when the nitrogen content is measured on the second main surface, in the same manner as on the first main surface, the nitrogen content obtained on the second main surface is almost identical to that on the first main surface.

[0055] Deviation in Nitrogen Content

[0056] In the continuous single growth sector of the single-crystal diamond substrate in Embodiment 1, the percentage of the difference between the maximum nitrogen content c2 and the average nitrogen content c1 relative to the average nitrogen content c1 {(c2-c1) / c1}×100 may be less than 50%, and the percentage of the difference between the average nitrogen content c1 and the minimum nitrogen content c3 relative to the average nitrogen content c1 {(c1-c3) / c1}×100 may be less than 50%.

[0057] Alternatively, the percentage {(c2-c1) / c1}×100 can be below 30%, and the percentage {(c1-c3) / c1}×100 can also be below 30%. Alternatively, the percentage {(c2-c1) / c1}×100 can be below 15%, and the percentage {(c1-c3) / c1}×100 can also be below 5%. There are no specific restrictions on the lower limits of the percentages {(c2-c1) / c1}×100 and {(c1-c3) / c1}×100; they can also be above 0%.

[0058] The maximum value c2 and the minimum value c3 of nitrogen content are respectively the maximum and minimum values ​​of nitrogen content in the measurement sites 3a, 3b, 3c, 3d and 3e set in the determination of the average value of nitrogen content c1.

[0059] <Maximum Length>

[0060] In Embodiment 1, the maximum length of the first and second main surfaces of the single-crystal diamond substrate can be 4 mm or more, 4 mm or more and 30 mm or less, 5 mm or more and 30 mm or less, 6 mm or more and 30 mm or less, or 7 mm or more and 30 mm or less.

[0061] In this disclosure, maximum length refers to the maximum length of the straight line connecting two points on the outer edge of the principal surface. The maximum lengths of the first and second principal surfaces of the single-crystal diamond substrate are measured using an optical microscope with length measurement capabilities.

[0062] <Face Orientation>

[0063] In Implementation Method 1, the orientation of the first and second principal planes of the single-crystal diamond substrate can also be a (lmn) plane satisfying l+m+n≤8. Both m and n are integers greater than or equal to 0.

[0064] The orientation of the first and second principal surfaces of the single-crystal diamond substrate in Embodiment 1 can also be (111) surface.

[0065] The orientation of the first and second main surfaces of the single-crystal diamond substrate in Embodiment 1 can also be (100) plane.

[0066] The orientation of the first and second main surfaces of the single-crystal diamond substrate in Embodiment 1 can also be (110) surface.

[0067] <Impurity of impurities other than nitrogen in a continuous single growth sector>

[0068] Alternatively, in the single-crystal diamond substrate of Embodiment 1, the total content of impurity elements other than nitrogen (hereinafter also referred to as "impurity element content") in a continuous single growth sector is lower than the nitrogen content and is 0.01 ppb or more and 5 ppm or less. The impurity element content of the continuous single growth sector may also be 0.01 ppb or more and 4 ppm or less, or it may be 0.01 ppb or more and 3 ppm or less.

[0069] Other than nitrogen, impurity elements include boron (B), aluminum (Al), silicon (Si), iron (Fe), nickel (Ni), chromium (Cr), cobalt (Co), manganese (Mn), titanium (Ti), zirconium (Zr), hafnium (Hf), gallium (Ga), and magnesium (Mg). When more than two impurity elements are present, the impurity element content refers to the total content of all impurity elements.

[0070] The impurity element content in a continuous, single growth sector was determined by SIMS. The analytical conditions and measurement sites can also be the same as those for the nitrogen content in the continuous, single growth sector described above.

[0071] <Application>

[0072] The single-crystal diamond substrate of Embodiment 1 is suitable for use in high-sensitivity magnetic sensors. Furthermore, the single-crystal diamond substrate of Embodiment 1 can also be used in infrared optical components (e.g., window materials for lasers, pressurized cells, prisms), laser windows, spectrometers, monochromators, anvils for ultra-high voltage generators, semiconductor diamond substrates, precision cutting tools, etc.

[0073] <Implementation Method 2: Method for Manufacturing a Single-Crystal Diamond Substrate>

[0074] The single-crystal diamond substrate of Embodiment 1 can be obtained by synthesizing single-crystal diamond on a seed crystal substrate using a temperature difference method under high temperature and high pressure and cutting the substrate out of the single-crystal diamond.

[0075] <Process for preparing single-crystal diamond seed substrate>

[0076] First, prepare the seed crystal substrate. Figure 7This is a cross-sectional view of the seed substrate 5 used in Embodiment 2. The seed substrate 5 has: a third main surface 5a for growing single-crystal diamond; an inclined surface 5c inclined relative to the third main surface 5a from an edge portion 5b; a fourth main surface 5e opposite to the third main surface 5a; and a side surface 5f connecting the inclined surface 5c and the fourth main surface 5e. The edge portion 5b of the third main surface 5a and the inclined surface 5c form a chamfered portion 5d. The angles α1 and α2 between the third main surface 5a and the inclined surface 5c exceed 90 degrees. The angles α3 and α4 between the side surface 5f and the inclined surface 5c exceed 90 degrees. The size of the seed substrate 5 can be 0.5 mm or more, 0.5 mm or more and 20 mm or less, 1.5 mm or more and 20 mm or less, 2 mm or more and 20 mm or less, 2.5 mm or more and 20 mm or less, or 3 mm or more and 20 mm or less.

[0077] The nitrogen content of the seed crystal substrate can be below 50 ppm, below 40 ppm, below 30 ppm, or below 20 ppm.

[0078] <Processes for growing single-crystal diamond>

[0079] Next, a temperature-pressure differential method is used to grow single-crystal diamond on a seed substrate. In the temperature-pressure differential method, for example, a substrate with... Figure 8 The sample chamber is configured as shown.

[0080] like Figure 8 As shown, in the sample chamber 10 used to manufacture single-crystal diamond 2, an insulator 52, a carbon source 53, a solvent metal 54, and a seed substrate 5 are arranged within a space surrounded by a graphite heater 57, and a pressure medium 56 is arranged outside the graphite heater 57. The high-temperature, high-pressure temperature difference method refers to the synthesis method described below: a longitudinal temperature gradient is set inside the sample chamber 10, and a high-temperature section (T...)... high Carbon source 53 is configured in the low-temperature section (T) low A seed crystal substrate 5 is configured, a solvent metal 54 is configured between the carbon source 53 and the seed crystal substrate 5, and the conditions are maintained above the temperature at which the solvent metal 54 melts and above the pressure at which the diamond becomes thermally stable, so that the single crystal diamond 2 grows on the seed crystal substrate 5.

[0081] In embodiment 2, as the seed substrate 5, a material such as... Figure 7 The diagram shows a seed substrate including a 5d chamfered portion. This suppresses the occurrence of internal cracks in single-crystal diamond originating from the corner of the seed substrate.

[0082] Diamond powder is preferably used as the carbon source 53. Graphite (black lead) or pyrolytic carbon can also be used as the carbon source 53. As the solvent metal 54, one or more metals selected from iron (Fe), cobalt (Co), nickel (Ni), and manganese (Mn), or alloys containing these metals, can also be used.

[0083] In solvent metal 54, at least one of the group selected from titanium (Ti), zirconium (Zr), hafnium (Hf), gallium (Ga), aluminum (Al), and magnesium (Mg) is added as a nitrogen getter at a total concentration of 0.1% to 20% by mass. Accordingly, the nitrogen content in the grown single-crystal diamond can be reduced to 50 ppm or less.

[0084] <Process for obtaining single-crystal diamond substrate>

[0085] Next, a single-crystal diamond substrate is cut from the single-crystal diamond. For example, a water-guided laser processing machine can also be used for cutting. By adjusting the cutting position and direction, the area of ​​a continuous single growth sector and the orientation of the main surface of the single-crystal diamond substrate can be adjusted. For example, as described below.

[0086] When in Figure 9 When the single-crystal diamond substrate 2 shown is cut at the position indicated by reference numeral P5, the orientation of the first principal surface 1a and the second principal surface 1b of the resulting single-crystal diamond substrate is (100). Furthermore, when the single-crystal diamond substrate is cut at the position indicated by reference numeral P6, the orientation of the first principal surface 1a and the second principal surface 1b of the resulting single-crystal diamond substrate is (110). Both the first and second principal surfaces of the resulting single-crystal diamond substrate contain 0.25 mm. 2 The above are (100) sectors that are continuous single growth sectors.

[0087] When in Figure 10 When the single-crystal diamond substrate 2 shown is cut at the position indicated by reference numeral P7, the orientation of the first principal surface 1a and the second principal surface 1b of the resulting single-crystal diamond substrate is (111). Furthermore, when the single-crystal diamond substrate is cut at the position indicated by reference numeral P8, the orientation of the first principal surface 1a and the second principal surface 1b of the resulting single-crystal diamond substrate is (110). Both the first and second principal surfaces of the resulting single-crystal diamond substrate contain 0.25 mm. 2 The above are sectors (111) that are continuous single growth sectors.

[0088] [Postscript 1]

[0089] The method for manufacturing a single-crystal diamond substrate according to Embodiment 2 of this disclosure is the same as the method for manufacturing a single-crystal diamond substrate described in Embodiment 1, comprising the following steps: preparing a single-crystal diamond seed substrate, the single-crystal diamond seed substrate including a third main surface and a fourth main surface opposite to the third main surface; growing single-crystal diamond on the third main surface using a temperature difference method under high temperature and high pressure; and cutting a single-crystal diamond substrate from the single-crystal diamond, the single-crystal diamond seed substrate including an inclined surface that is inclined relative to the third main surface from the edge portion of the third main surface and a side surface connecting the inclined surface and the fourth main surface, the angle between the third main surface and the inclined surface exceeding 90 degrees, and the angle between the inclined surface and the side surface exceeding 90 degrees.

[0090] [Postscript 2]

[0091] According to the method for manufacturing a single-crystal diamond substrate described in Appendix 1, the diameter of the inscribed circle of the third principal surface is 0.5 mm or more.

[0092] [Postscript 3]

[0093] According to the method for manufacturing a single-crystal diamond substrate as described in Appendix 1 or Appendix 2, in the step of growing the single-crystal diamond, at least one selected from the group consisting of titanium, zirconium, hafnium, gallium, aluminum and magnesium is added to a solvent metal at a total concentration of 0.1% by mass or more and 20% by mass or less.

[0094] Example

[0095] This embodiment is further illustrated by examples. However, this embodiment is not limited to these examples.

[0096] Fabrication of single-crystal diamond substrates

[0097] Regarding samples 1 to 6, as follows Figure 7 As shown, seed substrates including chamfered portions were prepared. In each seed substrate, the angles α1 and α2 between the third main surface and the inclined surface of the chamfered portion exceed 90 degrees. The angles α3 and α4 between the inclined surface of the chamfered portion and the side surface exceed 90 degrees.

[0098] For sample 7, a seed substrate excluding the chamfered portion was prepared.

[0099] In all samples, the orientation of the third principal surface for single-crystal diamond growth is the (100) plane. The nitrogen content of the seed substrate used for each sample and the diameter of the inscribed circle of the third principal surface for single-crystal diamond growth are shown in the "Nitrogen Content" and "Seed Substrate Dimensions" columns of Table 1.

[0100]

[0101] Next, using the Figure 8 The sample chamber shown is used to grow single-crystal diamond on a seed crystal substrate by using a temperature difference method under high temperature and high pressure, thus obtaining single-crystal diamond for each sample.

[0102] Diamond powder was used as the carbon source. The solvent metal composition was set to Fe / Co = 60 / 40 (mass ratio). To prevent dissolution of the seed substrate, approximately 4% by mass of carbon was added to the solvent. Furthermore, 1% by mass of Ti was added to the solvent as a nitrogen getter.

[0103] The carbon source and the seed substrate were placed in a graphite heater to create a temperature difference of approximately 30°C. Using an ultra-high pressure generator, the temperature was maintained at 5.5 GPa and 1300°C for 100 hours to grow single-crystal diamond on the seed substrate. Afterward, the temperature was lowered to room temperature, followed by decompression, and the grown single-crystal diamond was removed.

[0104] exist Figure 11 The single-crystal diamond substrates for each sample were cut from the extracted single-crystal diamond 2 at the location indicated by reference numeral P9 in the attached figure. In all samples, the orientation of the first principal surface 1a and the second principal surface 1b is the (100) plane. Regarding sample 7, the cut single-crystal diamond substrate fractured due to cracks generated inside the single-crystal diamond. Therefore, for sample 7, the area of ​​the largest continuous single growth sector without cracks in the fractured single-crystal diamond substrate was measured as described below.

[0105] <Area of ​​a continuous single growth sector>

[0106] In each sample, the area of ​​a continuous single growth sector was measured on the first and second principal surfaces of the single-crystal diamond substrate using the method described in Embodiment 1. The results are shown in Table 2. In cases where the areas of the continuous single growth sectors on the first and second principal surfaces differ, Table 2 shows the area of ​​the smaller sector.

[0107] <Determination of Nitrogen Content>

[0108] In the single-crystal diamond substrates of each sample, the nitrogen content of continuous single growth sectors was measured using the method described in Example 1, with an average value c1, a maximum value c2, and a minimum value c3. Based on the obtained values, {(c2-c1) / c1}×100 and {(c1-c3) / c1}×100 were calculated. The results are shown in Table 3.

[0109] <Maximum Length>

[0110] For each sample's single-crystal diamond substrate, the maximum lengths of the first and second principal planes were measured using the method described in Example 1. The results are shown in Table 2. In cases where the maximum lengths of the first and second principal planes differ, Table 2 shows the maximum length of the smaller one.

[0111] <Impurity of impurities other than nitrogen in a single growth sector>

[0112] The impurity element content was determined in a continuous, single growth sector on a single-crystal diamond substrate for each sample using the method described in Example 1. The results are shown in the "Impurity Element Content" column of Table 3.

[0113] <Number of diamond samples prepared with a diameter of 0.5 mm>

[0114] Diamond samples with a diameter of 0.5 mm were cut from a continuous, single growth sector on the single-crystal diamond substrate of each sample, and the number of diamond samples obtained was determined. The results are shown in the "Number of Diamonds for NV" column of Table 3.

[0115]

[0116] [Inspection]

[0117] The single-crystal diamond substrates of samples 1 to 5 correspond to the examples. The single-crystal diamond substrates of samples 6 and 7 correspond to the comparative examples. Compared with the single-crystal diamond substrates of the comparative examples, the single-crystal diamond substrates of the examples can produce more 0.5 mm square diamond samples of the same quality. This is because, in the single-crystal diamond substrates of the examples, the area of ​​the continuous single growth sector in the main surface is large, and the growth sector has a nitrogen concentration suitable for high-sensitivity magnetic sensors, thus enabling the production of high-sensitivity magnetic sensor diamonds of the same quality with a high yield.

[0118] The embodiments and examples of this disclosure have been described above, but appropriate combinations or various modifications of the above embodiments and examples were planned from the outset. It should be considered that the embodiments and examples disclosed herein are illustrative in all respects and not restrictive. The scope of the invention is shown by the claims rather than the above embodiments and examples, and is intended to include all changes within the meaning and scope equivalent to the claims.

[0119] Explanation of reference numerals in the attached figures

[0120] 1: Single-crystal diamond substrate

[0121] 1a: First Main Face

[0122] 1b: Second Main Page

[0123] 2: Single-crystal diamond

[0124] 5: Single-crystal diamond seed substrate

[0125] 5a: Third Main Face

[0126] 5b: Edge

[0127] 5c: Inclined surface

[0128] 5d: Chamfered part

[0129] 5e: Fourth Main Face

[0130] 5f: Side view

[0131] 10: Sample Chamber

[0132] 52: Insulator

[0133] 53: Carbon source

[0134] 54: Solvent metal

[0135] 56: Pressure medium

[0136] 57: Graphite heater

[0137] 70: Grinding device

[0138] 71: Sample Holder

[0139] 72: Metal-bonded diamond grinding wheel

[0140] 20: Boundary

[0141] 3a, 3b, 3c, 3d, 3e: Measurement sites

[0142] C1: Largest inscribed circle

[0143] P1, P5, P6, P7, P8, P9: Cutout positions.

Claims

1. A single-crystal diamond substrate, comprising a first main surface and a second main surface opposite to the first main surface, The first main surface and the second main surface each have an area of ​​0.25 mm. 2 The above are continuous single growth sectors. The average nitrogen content (c1) in the growth sector, based on atomic number, is above 0.01 ppm and below 50 ppm.

2. The single-crystal diamond substrate according to claim 1, wherein, The area of ​​the growth sector is 5 mm. 2 above.

3. The single-crystal diamond substrate according to claim 1 or 2, wherein, The orientation of the first principal surface and the second principal surface is a (lmn) surface that satisfies l+m+n≤8.

4. The single-crystal diamond substrate according to any one of claims 1 to 3, wherein, The orientation of the first main face and the second main face is (111) face.

5. The single-crystal diamond substrate according to any one of claims 1 to 3, wherein, The orientation of the first main face and the second main face is (100) face.

6. The single-crystal diamond substrate according to any one of claims 1 to 3, wherein, The orientation of the first main face and the second main face is (110) face.

7. The single-crystal diamond substrate according to any one of claims 1 to 6, wherein, The total content of impurity elements other than nitrogen in the growth sector, based on atomic number, is lower than the content of nitrogen based on atomic number, and is above 0.01 ppb and below 5 ppm.

8. The single-crystal diamond substrate according to any one of claims 1 to 7, wherein, In the growth sector, The difference between the maximum value c2 of the nitrogen content based on atomic number and the average value c1 of the nitrogen content based on atomic number, as a percentage of the average value c1 {(c2-c1) / c1}×100, is less than 50%, and The difference between the average value c1 and the minimum nitrogen content c3 based on the number of atoms is less than 50% of the average value c1 as a percentage {(c1-c3) / c1}×100.

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