Indium phosphide single crystal substrate, indium phosphide single crystal, and method for producing indium phosphide single crystal

Abstract

Provided is an indium phosphide single crystal substrate having a main surface. The indium phosphide single crystal substrate contains a dopant. The diameter of the main surface is 150-160 mm. The dislocation density in the main surface is 90 cm-2 or less. When the concentration of the dopant at the center of the main surface is a first concentration and the concentration of the dopant at the outer edge of the main surface is a second concentration, the value obtained by dividing by the first concentration the absolute value of the value obtained by subtracting the second concentration from the first concentration, is 11.9% or less.

Description

Indium phosphide single crystal substrate, indium phosphide single crystal, and method for manufacturing indium phosphide single crystal

[0001] The present disclosure relates to indium phosphide single crystal substrates, indium phosphide single crystals, and methods for manufacturing indium phosphide single crystals.

[0002] Japanese Patent Laid-Open No. 2019-043788 (Patent Document 1) describes a method for fabricating a semiconductor device with an average dislocation density of 2500 / cm ２ An indium phosphide single crystal is described in which

[0003] Japanese Patent Application Laid-Open No. 2019-043788

[0004] The indium phosphide single crystal substrate according to the present disclosure has a primary surface. The indium phosphide single crystal substrate contains a dopant. The primary surface has a diameter of 150 mm or more and 160 mm or less. The dislocation density in the primary surface is 90 cm －２ When the concentration of the dopant at the center of the main surface is defined as a first concentration and the concentration of the dopant at the outer edge of the main surface is defined as a second concentration, the absolute value of the difference between the first concentration and the second concentration divided by the first concentration is 11.9% or less.

[0005] FIG. 1 is a schematic plan view showing the configuration of an indium phosphide single crystal substrate according to this embodiment. FIG. 2 is a schematic side view showing the configuration of an indium phosphide single crystal substrate according to this embodiment. FIG. 3 is a schematic plan view showing the measurement position of the dopant concentration of an indium phosphide single crystal substrate. FIG. 4 is a schematic plan view showing the measurement position of the dislocation density in an indium phosphide single crystal substrate. FIG. 5 is a schematic plan view showing the configuration of an indium phosphide single crystal according to this embodiment. FIG. 6 is a schematic side view showing the configuration of an indium phosphide single crystal according to this embodiment. FIG. 7 is a schematic plan view showing the measurement position of the dopant concentration at a first end facet. FIG. 8 is a schematic bottom view showing the measurement position of the dopant concentration at a second end facet. FIG. 9 is a schematic cross-sectional view showing the configuration of an indium phosphide single crystal growth apparatus according to this embodiment. FIG. 10 is a schematic bottom view showing the configuration of a stirring member. FIG. 11 is a flow chart showing an outline of a method for producing an indium phosphide single crystal according to this embodiment. FIG. 12 is a partial cross-sectional view showing a step of preparing a growth apparatus. FIG. 13 is a cross-sectional schematic diagram showing a crucible in which a seed crystal, an indium phosphide raw material, and a sealing material are placed. FIG. 14 is a cross-sectional schematic diagram showing a process of melting raw materials. FIG. 15 is a cross-sectional schematic diagram showing a process of inserting a stirring member into an indium phosphide melt. FIG. 16 is a bottom view schematic diagram showing the operation of the stirring member in the crystal growth process. FIG. 17 is a schematic diagram showing the relationship between the inclination angle of the blade with respect to the <011> direction and time. FIG. 18 is a cross-sectional schematic diagram showing the crystal growth process. FIG. 19 is a partial cross-sectional schematic diagram showing the configuration of an indium phosphide single crystal growth apparatus according to a modified example of this embodiment. FIG. 20 is a bottom view schematic diagram showing the configuration of a stirring member according to a modified example of this embodiment.

[0006] [Problem to be Solved by the Present Disclosure] An object of the present disclosure is to provide an indium phosphide single crystal substrate, an indium phosphide single crystal, and a method for manufacturing an indium phosphide single crystal that can improve the yield of semiconductor elements.

[0007] Effect of the Present Disclosure According to the present disclosure, it is possible to provide an indium phosphide single crystal substrate, an indium phosphide single crystal, and a method for manufacturing an indium phosphide single crystal that can improve the yield of semiconductor elements.

[0008] [Outline of the embodiment] First, an outline of the embodiment of the present disclosure (also referred to as the present embodiment) will be described. In the crystallographic descriptions in this specification, individual orientations are represented by [ ], collective orientations by < >, individual planes by ( ), and collective planes by {}. Furthermore, for negative indices, in crystallography, a "-" (bar) is placed before the number, but in this specification, a negative sign is placed before the number.

[0009] (1) An indium phosphide single crystal substrate according to the present disclosure has a primary surface. The indium phosphide single crystal substrate contains a dopant. The primary surface has a diameter of 150 mm or more and 160 mm or less. The dislocation density in the primary surface is 90 cm －２ When the concentration of the dopant at the center of the main surface is defined as a first concentration and the concentration of the dopant at the outer edge of the main surface is defined as a second concentration, the absolute value of the difference between the first concentration and the second concentration divided by the first concentration is 11.9% or less.

[0010] In this way, the dislocation density in the main surface is sufficiently reduced, and the variation in dopant concentration in the main surface is also sufficiently reduced, which can improve the yield of semiconductor devices manufactured using the indium phosphide single crystal substrate.

[0011] (2) In the indium phosphide single crystal substrate according to (1) above, the main surface may have a central square region that includes the center of the main surface and has a side length of 40 mm, and a first outer rectangular region, a second outer rectangular region, a third outer rectangular region, and a fourth outer rectangular region that are oriented in the

[011] direction, the [0-1-1] direction, the [01-1] direction, and the [0-11] direction, respectively, relative to the central square region. The length of each of the short sides of the first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region may be 20 mm. The length of each of the long sides of the first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region may be 40 mm. When the distance between the outer peripheral edge of each of the first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region and the center of the main surface is a first numerical value, the radius of the main surface is a second numerical value, and the first numerical value and the second numerical value are each expressed in mm, the first numerical value may be a value obtained by dividing the second numerical value by 10, truncating the decimal point, and multiplying the result by 10. When the dislocation density in the central square region is a first density, and the average of the dislocation densities in the first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region is a second density, the value obtained by dividing the second density by the first density may be less than 203%. When the average value of the dislocation density in the first peripheral rectangular region and the dislocation density in the second peripheral rectangular region is defined as a third density, and the average value of the dislocation density in the third peripheral rectangular region and the dislocation density in the fourth peripheral rectangular region is defined as a fourth density, the value obtained by dividing the fourth density by the third density may be greater than 84% and not more than 113%.

[0012] In this way, the variation in dislocation density on the main surface is sufficiently reduced, which can improve the yield of semiconductor devices manufactured using the indium phosphide single crystal substrate.

[0013] (3) According to the indium phosphide single crystal substrate according to (1) or (2), the dislocation density on the main surface is 60 cm －２ It may be the following:

[0014] (4) In the indium phosphide single crystal substrate according to any one of (1) to (3) above, the absolute value of the difference between the first concentration and the second concentration divided by the first concentration may be less than 7%.

[0015] (5) In the indium phosphide single crystal substrate according to any one of (1) to (4) above, the dopant may be sulfur.

[0016] (6) In the indium phosphide single crystal substrate according to any one of (1) to (4) above, the dopant may be iron.

[0017] (7) In the indium phosphide single crystal substrate according to any one of (1) to (4) above, the dopant may be tin.

[0018] (8) In the indium phosphide single crystal substrate according to any one of (1) to (7), the primary surface may be a {100} plane. In this way, even if the growth direction is the <100> direction, the occurrence of twins is suppressed.

[0019] (9) In the indium phosphide single crystal substrate according to (1) above, the main surface may have a central square region including the center of the main surface and having a side length of 40 mm, and a first outer rectangular region, a second outer rectangular region, a third outer rectangular region, and a fourth outer rectangular region oriented in the

[011] , [0-1-1], [01-1], and [0-11] directions, respectively, relative to the central square region. The length of each of the short sides of the first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region may be 20 mm. The length of each of the long sides of the first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region may be 40 mm. When the distance between the outer peripheral edge of each of the first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region and the center of the main surface is a first numerical value, the radius of the main surface is a second numerical value, and the first numerical value and the second numerical value are each expressed in mm, the first numerical value may be a value obtained by dividing the second numerical value by 10, truncating the decimal point, and multiplying the result by 10. When the dislocation density in the central square region is a first density, and the average of the dislocation densities in the first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region is a second density, the value obtained by dividing the second density by the first density may be less than 203%. When the average value of the dislocation density in the first peripheral rectangular region and the dislocation density in the second peripheral rectangular region is defined as a third density, and the average value of the dislocation density in the third peripheral rectangular region and the dislocation density in the fourth peripheral rectangular region is defined as a fourth density, the value obtained by dividing the fourth density by the third density may be greater than 84% and not more than 113%. －２ The absolute value of the first concentration minus the second concentration divided by the first concentration may be less than 7%.

[0020] (10) An indium phosphide single crystal according to the present disclosure is an indium phosphide single crystal having a first end face and a second end face opposite the first end face. The indium phosphide single crystal contains a dopant. The diameter of the first end face is 150 mm or more and 160 mm or less. The length of the indium phosphide single crystal in the direction from the second end face toward the first end face is 50 mm or more and 200 mm or less. At least one of the dislocation density at the first end face and the dislocation density at the second end face is 90 cm －２ When the dopant concentration at the center of the first end face is a third concentration, the dopant concentration at the outer edge of the first end face is a fourth concentration, the dopant concentration at the center of the second end face is a fifth concentration, and the dopant concentration at the outer edge of the second end face is a sixth concentration, at least one of the absolute value of the difference between the third concentration and the fourth concentration divided by the third concentration and the absolute value of the difference between the fifth concentration and the sixth concentration divided by the fifth concentration is 11.9% or less.

[0021] In this way, the dislocation density is sufficiently reduced in at least one of the first facet and the second facet, and the variation in dopant concentration is sufficiently reduced in at least one of the first facet and the second facet, which can improve the yield of semiconductor devices manufactured using the indium phosphide single crystal.

[0022] (11) A method for producing an indium phosphide single crystal according to the present disclosure includes the following steps: a seed crystal is placed inside a crucible; an indium phosphide source material is placed on the seed crystal; an indium phosphide melt is prepared by melting a portion of the seed crystal and the indium phosphide source material; a stirring member is inserted into the indium phosphide melt inside the crucible; the indium phosphide melt is solidified by stirring the indium phosphide melt using the stirring member while moving the crucible; the stirring member has a main body and at least one blade; the main body is configured to be rotatable; the at least one blade is attached to the main body; the at least one blade extends in a radial direction perpendicular to the rotation axis of the main body; and in the step of solidifying the indium phosphide melt, the at least one blade repeatedly reciprocates along the rotation direction of the main body. During the reciprocating motion, a state in which the at least one blade faces the <011> direction of the seed crystal occurs multiple times. The angular amplitude of at least one wing in the reciprocating motion is greater than or equal to 10° and less than or equal to 45°.

[0023] This allows the indium phosphide melt near the <011> direction of the seed crystal to be sufficiently stirred. Therefore, in the indium phosphide single crystal, the occurrence of twins can be suppressed while the dopant concentration variation and dislocation density can be reduced. As a result, the yield of semiconductor devices can be improved.

[0024] (12) According to the method for producing an indium phosphide single crystal according to (11) above, at least one of the blades may have four blades, thereby enabling more effective stirring of the indium phosphide melt.

[0025] (13) According to the method for producing an indium phosphide single crystal according to (11) or (12) above, the angular amplitude may be 15° or more.

[0026] (14) In the method for producing an indium phosphide single crystal according to any one of (11) to (13) above, the period of the reciprocating motion may be 60 seconds or more and 300 seconds or less, thereby making it possible to effectively stir the indium phosphide melt and extend the life of the blades.

[0027] (15) In the method for producing an indium phosphide single crystal according to any one of (11) to (14) above, the main body may have a disk member. The disk member may extend in a radial direction. At least one blade may be attached to the disk member. This can extend the life of the blade.

[0028] (16) In the method for producing an indium phosphide single crystal according to any one of (11) to (15) above, the thickness of at least one of the blades in the direction of extension of the rotation axis of the main body may be 3 mm or more and 10 mm or less, thereby enabling the indium phosphide melt to be effectively stirred and the life of the blade to be extended.

[0029] (17) In the method for producing an indium phosphide single crystal according to any one of (11) to (16) above, the length of at least one of the blades in the radial direction may be 10 mm or more and 70 mm or less, thereby enabling the indium phosphide melt to be effectively stirred and the life of the blade to be extended.

[0030] (18) In the method for producing an indium phosphide single crystal according to any one of (11) to (17), the shortest distance between at least one blade portion and the solid-liquid interface of the indium phosphide melt in the direction of extension of the rotation axis of the main body may be 20 mm or less, thereby enabling effective stirring of the portion of the indium phosphide melt close to the solid-liquid interface.

[0031] (19) According to the method for producing an indium phosphide single crystal according to any one of (11) to (17) above, at least one wing portion may be made of quartz or carbon covered with pyrolytic boron nitride.

[0032] [Details of the embodiment] Hereinafter, details of the embodiment of the present disclosure will be described with reference to the drawings. Note that in the following drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0033] <Indium phosphide single crystal substrate> First, the configuration of an indium phosphide single crystal substrate 100 (hereinafter also referred to as an InP single crystal substrate 100) according to this embodiment will be described. FIG. 1 is a plan view schematic diagram showing the configuration of the InP single crystal substrate 100 according to this embodiment. FIG. 2 is a side view schematic diagram showing the configuration of the InP single crystal substrate 100 according to this embodiment. As shown in FIGS. 1 and 2, the InP single crystal substrate 100 has a first main surface 1, a second main surface 2, and an outer peripheral surface 3.

[0034] The first main surface 1 is, for example, planar. When viewed along a line perpendicular to the first main surface 1 (hereinafter also referred to as a planar view), the shape of the first main surface 1 is, for example, circular. The first main surface 1 includes a first center A1. The first main surface 1 extends along each of a first direction 101 and a second direction 102.

[0035] The first main surface 1 is a {100} plane of the single-crystal indium phosphide constituting the indium phosphide single crystal substrate 100. The first direction 101 and the second direction 102 are each a <011> direction. The second direction 102 is a direction perpendicular to the first direction 101. The first direction 101 is, for example, the

[011] direction. The second direction 102 is, for example, the [01-1] direction.

[0036] As shown in FIG. 2 , the second main surface 2 is opposite the first main surface 1. The direction from the second main surface 2 toward the first main surface 1 is defined as a third direction 103. The third direction 103 is the growth direction of the InP single crystal when the InP single crystal substrate 100 is manufactured. The third direction 103 is the <100> direction. The outer peripheral surface 3 is continuous with each of the first main surface 1 and the second main surface 2. The ridge line between the first main surface 1 and the outer peripheral surface 3 is defined as a first outer edge 8. From another perspective, the first outer edge 8 is the outer edge of the first main surface 1.

[0037] As shown in FIG. 1 , the diameter of the first main surface 1 is defined as a first diameter W1. The first diameter W1 is equal to or greater than 150 mm and equal to or less than 160 mm. The first diameter W1 may be, for example, 6 inches (152.4 mm) or greater, or may be 154 mm or greater. The first diameter W1 may be, for example, 158 mm or less, or may be 156 mm or less. The first diameter W1 is the longest distance between two different points on the first outer edge 8.

[0038] At least one of a notch, an orientation flat, and an index flat may be provided on the outer peripheral surface 3. When at least one of a notch, an orientation flat, and an index flat is provided on the outer peripheral surface 3, the center of a circle including an arc along the arc-shaped portion of the outer peripheral surface 3 in a plan view is defined as the first center A1.

[0039] <Dopant Concentration in Indium Phosphide Single Crystal Substrate> The InP single crystal substrate 100 contains a dopant. The dopant is one of sulfur (S), iron (Fe), and tin (Sn). FIG. 3 is a plan view schematic diagram showing measurement positions of the dopant concentration of the InP single crystal substrate 100. As shown in FIG. 3, the first main surface 1 has a first central rectangular region 10, a fifth peripheral rectangular region 15, and a sixth peripheral rectangular region 16. The first central rectangular region 10, the fifth peripheral rectangular region 15, and the sixth peripheral rectangular region 16 are each a region where the dopant concentration is measured. In a plan view, the first central rectangular region 10, the fifth peripheral rectangular region 15, and the sixth peripheral rectangular region 16 each have a rectangular shape. The length of the short side of each of the first central rectangular region 10, the fifth peripheral rectangular region 15, and the sixth peripheral rectangular region 16 is, for example, 2 mm. The length of the long side of each of the first central rectangular region 10, the fifth outer peripheral rectangular region 15, and the sixth outer peripheral rectangular region 16 is, for example, 20 mm.

[0040] An imaginary line passing through the first center A1 and parallel to the first direction 101 is defined as a first imaginary line 91. An imaginary line passing through the first center A1 and parallel to the second direction 102 is defined as a second imaginary line 92. In a plan view, the first central rectangular region 10, the fifth outer peripheral rectangular region 15, and the sixth outer peripheral rectangular region 16 are each located in the second direction 102 with respect to the first imaginary line 91. In a plan view, the first central rectangular region 10, the fifth outer peripheral rectangular region 15, and the sixth outer peripheral rectangular region 16 are each located in the first direction 101 with respect to the second imaginary line 92.

[0041] In a plan view, the corners of the first central rectangular region 10 overlap the first center A1. In a plan view, the short sides of the first central rectangular region 10 overlap the first imaginary straight line 91. In a plan view, the long sides of the first central rectangular region 10 overlap the second imaginary straight line 92.

[0042] The fifth outer rectangular region 15 is located in the first direction 101 relative to the first central rectangular region 10. The fifth outer rectangular region 15 is in contact with the first outer edge 8. In a plan view, the short side of the fifth outer rectangular region 15 overlaps with the first imaginary straight line 91.

[0043] The sixth outer rectangular region 16 is located in the second direction 102 relative to the first central rectangular region 10. The sixth outer rectangular region 16 is in contact with the first outer edge 8. In a plan view, the short side of the sixth outer rectangular region 16 overlaps with the second imaginary straight line 92.

[0044] Next, a method for measuring the dopant concentration will be described. The dopant concentration is measured, for example, using glow discharge mass spectrometry (GDMS). For GDMS, for example, a glow discharge mass spectrometer VG-9000 manufactured by VG-Elemental is used. In GDMS, a glow discharge plasma is generated in a high-purity argon atmosphere using the analytical sample as the cathode. The surface of the analytical sample is sputtered in the plasma, and the ionized constituent elements in the analytical sample are measured using a mass spectrometer.

[0045] GDMS is performed, for example, according to the following procedure. Specifically, first, the sample placement area of ​​the glow discharge mass spectrometer is cleaned to prevent and remove foreign matter. The sample placement area is then pre-sputtered for, for example, 60 minutes. The analytical value obtained during pre-sputtering is used as the background.

[0046] The InP single crystal substrate 100 is diced or scribed and then cleaved along the outer edges of the first central rectangular region 10, the fifth peripheral rectangular region 15, and the sixth peripheral rectangular region 16 to prepare a strip-shaped sample for a pin-shaped cell. This pin-shaped cell is used as an ion source. The pin-shaped cell sample has a width of 2 mm, a length of 20 mm, and a thickness of 0.6 mm to 1 mm. During analysis, the pin-shaped cell holder is cooled using liquid nitrogen.

[0047] In GDMS, for example, the following measurement conditions are used: Specifically, the diameter of the discharge surface is 10 mm; the discharge gas is argon gas with a purity of 6N; the discharge current is 2 mA, for example; the discharge voltage is 1 kV, for example; the glow discharge is in constant current mode; the detector is a Faraday cup and multiplier; the mass resolution (m / Δm) is approximately 4000 (high resolution mode); and the relative sensitivity coefficient is, for example, a value built into the software attached to the glow discharge mass spectrometer. In this manner, the dopant concentration of the InP single crystal substrate 100 is measured.

[0048] The dopant concentration in the first central rectangular region 10 is set to a first concentration. The first concentration is considered to be the dopant concentration at the first center A1 of the first main surface 1. The first concentration is, for example, 1.0×10 １６ cm －３ 1x10 or more １９ cm －３ The following is the result.

[0049] The average value of the dopant concentration in the fifth peripheral rectangular region 15 and the dopant concentration in the sixth peripheral rectangular region 16 is set to a second concentration. The second concentration is considered to be the dopant concentration at the first outer edge 8 of the first main surface 1. The second concentration is, for example, 1.0×10１６ cm －３ 1x10 or more １９ cm －３ The following is the result.

[0050] The second concentration is, for example, lower than the first concentration. The absolute value of the value obtained by subtracting the second concentration from the first concentration and dividing the result (first value) by the first concentration is 11.9% or less. The first value may be, for example, 0.1% or more, or 1% or more. The first value may be, for example, 10% or less, less than 7%, or 6.5% or less.

[0051] <Dislocation Density in Indium Phosphide Single Crystal Substrate> Dislocations exist in the InP single crystal substrate 100 according to this embodiment. In this specification, "dislocations" refers to one type of crystal defect, and in this technical field, dislocations correspond to etch pits confirmed using the measurement method described below. Therefore, the number of dislocations can be indirectly measured by measuring the number of etch pits. In this specification, the number of dislocations is measured in a density of 1 cm. ２ By measuring the number of such etch pits per 1000 nm, the dislocation density is measured.

[0052] FIG. 4 is a plan view schematic showing measurement positions of dislocation density in an InP single crystal substrate 100. As shown in FIG. 4, the first main surface 1 has an outer peripheral region 18 and a central region 19. The outer peripheral region 18 is continuous with the first outer edge 8. The central region 19 is surrounded by the outer peripheral region 18. The central region 19 is continuous with the outer peripheral region 18. The radius of the central region 19 is defined as a first radius R1. The radius of the first main surface 1 is defined as a second radius R2. The second radius R2 is the value obtained by dividing the first diameter W1 (see FIG. 1 ) by 2. When the first radius R1 and the second radius R2 are each expressed in mm, the first radius R1 is the value obtained by dividing the second radius R2 by 10, rounding down the decimal point, and multiplying the result by 10. Specifically, for example, when the first diameter W1 is 150 mm, the second radius R2 is 75 mm and the first radius R1 is 70 mm.

[0053] 4, in the measurement of dislocation density, the central region 19 is virtually divided into a plurality of square regions 5. In a plan view, the shape of each of the plurality of square regions 5 is substantially square. The length of one side of each of the plurality of square regions 5 (first length L1) is 10 mm.

[0054] First, a square circumscribing the central region 19 in plan view is assumed. The length of one side of the square is twice the first radius R1. The square is divided into 10 mm × 10 mm square regions. Of the square regions, those whose centers are in the central region 19 are considered to be multiple square regions 5 that divide the central region 19. One side of each of the multiple square regions 5 is parallel to the first direction 101. In plan view, corners of four of the multiple square regions 5 overlap the first center A1.

[0055] As shown in Figure 4, the first main surface 1 has a central square region 17, a first peripheral rectangular region 11, a second peripheral rectangular region 12, a third peripheral rectangular region 13, and a fourth peripheral rectangular region 14. The central square region 17 includes a first center A1 of the first main surface 1. The length of one side of the central square region 17 is 40 mm. The one side of the central square region 17 is parallel to the first direction 101. The central square region 17 includes 16 square regions 5.

[0056] One side of each of the first outer rectangular region 11, the second outer rectangular region 12, the third outer rectangular region 13, and the fourth outer rectangular region 14 is parallel to the first direction 101. Each of the first outer rectangular region 11, the second outer rectangular region 12, the third outer rectangular region 13, and the fourth outer rectangular region 14 includes eight square regions 5. The first outer rectangular region 11, the second outer rectangular region 12, the third outer rectangular region 13, and the fourth outer rectangular region 14 are oriented in the

[011] direction, the [0-1-1] direction, the [01-1] direction, and the [0-11] direction, respectively, relative to the central square region 17.

[0057] The length of the short side of each of the first outer rectangular region 11, the second outer rectangular region 12, the third outer rectangular region 13, and the fourth outer rectangular region 14 is 20 mm. The length of the long side of each of the first outer rectangular region 11, the second outer rectangular region 12, the third outer rectangular region 13, and the fourth outer rectangular region 14 is 40 mm. The distance between the outer peripheral edge of each of the first outer rectangular region 11, the second outer rectangular region 12, the third outer rectangular region 13, and the fourth outer rectangular region 14 and the first center A1 of the first main surface 1 is a first radius R1. From another perspective, the outer peripheral edge of each of the first outer rectangular region 11, the second outer rectangular region 12, the third outer rectangular region 13, and the fourth outer rectangular region 14 is circumscribed by the boundary between the central region 19 and the outer peripheral region 18. Assume that the distance between the first center A1 and the outer edge of each of the first outer rectangular region 11, the second outer rectangular region 12, the third outer rectangular region 13, and the fourth outer rectangular region 14 is the first numerical value, the second radius R2 is the second numerical value, and the units of the first numerical value and the second numerical value are each mm. In this case, the first numerical value is the integer value obtained by dividing the second numerical value by 10, discarding any decimal points, and multiplying the result by 10.

[0058] Next, a method for measuring dislocation density will be described. First, a Huber etchant is prepared. The Huber etchant contains phosphoric acid and hydrogen bromide. The mass ratio of phosphoric acid to hydrogen bromide in the Huber etchant is 2:1. The temperature of the Huber etchant is set to, for example, 20°C. The InP single crystal substrate 100 is immersed in the Huber etchant for, for example, 2 minutes to 7 minutes. This forms etch pits on the first main surface 1.

[0059] Next, each of the plurality of square regions 5 is observed using an optical microscope. Specifically, the number of etch pits in a 1 mm × 1 mm square measurement region centered at the center O of each of the plurality of square regions 5 is measured using the optical microscope. The value obtained by dividing the measured number of etch pits by the area of ​​the square measurement region is defined as the dislocation density in the square region 5.

[0060] The sum of the etch pit densities of the plurality of square regions 5 divided by the number of the plurality of square regions 5 is defined as the dislocation density on the first main surface 1. The dislocation density on the first main surface 1 is 90 cm －２ The dislocation density on the first main surface 1 is, for example, 1 cm －２ It may be more than 10 cm －２ The dislocation density in the first main surface 1 may be, for example, 75 cm －２ It may be less than 65 cm －２ It may be less than 60 cm －２ It may be the following:

[0061] The sum of the etch pit densities of the plurality of square regions 5 included in the central square region 17 divided by 16 is defined as the dislocation density (first density) in the central square region 17. The first density is considered to be the dislocation density at the first center A1 of the first main surface 1. The first density is, for example, 30 cm －２ 80cm or more －２ The following is the result.

[0062] The sum of the etch pit densities of the square regions 5 included in each of the first peripheral rectangular region 11, the second peripheral rectangular region 12, the third peripheral rectangular region 13, and the fourth peripheral rectangular region 14 divided by 8 is defined as the dislocation density in the first peripheral rectangular region 11, the dislocation density in the second peripheral rectangular region 12, the dislocation density in the third peripheral rectangular region 13, and the dislocation density in the fourth peripheral rectangular region 14, respectively. The average value of the dislocation density in the first peripheral rectangular region 11, the dislocation density in the second peripheral rectangular region 12, the dislocation density in the third peripheral rectangular region 13, and the dislocation density in the fourth peripheral rectangular region 14 is defined as the second density. The second density is considered to be the dislocation density at the first outer edge 8 of the first main surface 1. The second density is, for example, equal to or less than the first density. The second density is, for example, 30 cm －２ 130cm or more －２ The following is the result.

[0063] The value obtained by dividing the second density by the first density (second value A) is less than 203%. The second value A may be, for example, 80% or more, or 90% or more. The second value A may be, for example, 195% or less, 150% or less, 130% or less, or 110% or less.

[0064] The average value of the dislocation density in the first peripheral rectangular region 11 and the dislocation density in the second peripheral rectangular region 12 is set to a third density. The average value of the dislocation density in the third peripheral rectangular region 13 and the dislocation density in the fourth peripheral rectangular region 14 is set to a fourth density. The fourth density may be equal to or greater than the third density. The value obtained by dividing the fourth density by the third density (second value B) is, for example, greater than 84% and equal to or less than 113%. The second value B may be, for example, equal to or greater than 95%, or equal to or greater than 105%. The second value B may be, for example, equal to or less than 111%, or equal to or less than 109%.

[0065] <Indium phosphide single crystal> Next, the configuration of the indium phosphide single crystal 200 (hereinafter also referred to as InP single crystal 200) according to this embodiment will be described. Fig. 5 is a schematic plan view showing the configuration of the InP single crystal 200 according to this embodiment. Fig. 6 is a schematic side view showing the configuration of the InP single crystal 200 according to this embodiment. As shown in Figs. 5 and 6, the InP single crystal 200 has a first end face 21, a second end face 22, and a cylindrical surface 23.

[0066] The first end facet 21 is, for example, planar. When viewed along a line perpendicular to the first end facet 21, the shape of the first end facet 21 is, for example, circular. The first end facet 21 includes a second center A2. The first end facet 21 extends along both a first direction 101 and a second direction 102. The first end facet 21 is a {100} plane of the single-crystal indium phosphide that constitutes the InP single crystal 200.

[0067] 6 , the second end face 22 is opposite the first end face 21. The direction from the second end face 22 toward the first end face 21 is a third direction 103. The direction from the second end face 22 toward the first end face 21 is the growth direction of the InP single crystal 200.

[0068] The length of the InP single crystal 200 in the third direction 103 (second length L2) is 50 mm or more and 200 mm or less. The second length L2 may be, for example, 70 mm or more, or 90 mm or more. The second length L2 may be, for example, 180 mm or less, or 160 mm or less.

[0069] The cylindrical surface 23 is continuous with each of the first end surface 21 and the second end surface 22. The ridge line between the first end surface 21 and the cylindrical surface 23 is defined as a second outer edge 28. The ridge line between the second end surface 22 and the cylindrical surface 23 is defined as a third outer edge 29.

[0070] As shown in FIG. 5 , the diameter of the first end surface 21 is defined as a second diameter W2. The second diameter W2 is equal to or greater than 150 mm and equal to or less than 160 mm. The second diameter W2 may be, for example, equal to or greater than 6 inches (152.4 mm), or may be equal to or greater than 154 mm. The second diameter W2 may be, for example, equal to or less than 158 mm, or may be equal to or less than 156 mm. The second diameter W2 is the longest distance between any two different points on the second outer edge 28.

[0071] At least one of a notch, an orientation flat, and an index flat may be provided on the cylindrical surface 23. When at least one of a notch, an orientation flat, and an index flat is provided on the cylindrical surface 23, the center of a circle including an arc along the arc-shaped portion of the cylindrical surface 23 when viewed along a straight line perpendicular to the first end face 21 is defined as the second center A2.

[0072] <Dopant Concentration in Indium Phosphide Single Crystal> The InP single crystal 200 contains a dopant, which is any one of sulfur (S), iron (Fe), and tin (Sn).

[0073] FIG. 7 is a schematic plan view showing the measurement positions of the dopant concentration on the first end face 21. As shown in FIG. 7, the first end face 21 has a second central rectangular region 20, a seventh peripheral rectangular region 25, and an eighth peripheral rectangular region 26. The second central rectangular region 20, the seventh peripheral rectangular region 25, and the eighth peripheral rectangular region 26 are each a region where the dopant concentration is measured. When viewed along a line perpendicular to the first end face 21, the second central rectangular region 20, the seventh peripheral rectangular region 25, and the eighth peripheral rectangular region 26 each have a rectangular shape. The length of the short side of each of the second central rectangular region 20, the seventh peripheral rectangular region 25, and the eighth peripheral rectangular region 26 is, for example, 2 mm. The length of the long side of each of the second central rectangular region 20, the seventh peripheral rectangular region 25, and the eighth peripheral rectangular region 26 is, for example, 20 mm.

[0074] An imaginary line passing through the second center A2 and parallel to the first direction 101 is defined as a third imaginary line 93. An imaginary line passing through the second center A2 and parallel to the second direction 102 is defined as a fourth imaginary line 94. When viewed along a line perpendicular to the first end face 21, the second central rectangular region 20, the seventh outer peripheral rectangular region 25, and the eighth outer peripheral rectangular region 26 each lie in the second direction 102 with respect to the third imaginary line 93. When viewed along a line perpendicular to the first end face 21, the second central rectangular region 20, the seventh outer peripheral rectangular region 25, and the eighth outer peripheral rectangular region 26 each lie in the first direction 101 with respect to the fourth imaginary line 94.

[0075] When viewed along a line perpendicular to the first end face 21, a corner of the second central rectangular region 20 overlaps the second center A2. When viewed along a line perpendicular to the first end face 21, a short side of the second central rectangular region 20 overlaps the third imaginary line 93. When viewed along a line perpendicular to the first end face 21, a long side of the second central rectangular region 20 overlaps the fourth imaginary line 94.

[0076] The seventh outer rectangular region 25 is located in the first direction 101 relative to the second central rectangular region 20. The seventh outer rectangular region 25 is tangent to the second outer edge 28. When viewed along a line perpendicular to the first end face 21, the short side of the seventh outer rectangular region 25 overlaps the third imaginary line 93.

[0077] The eighth outer rectangular region 26 is in the second direction 102 relative to the second central rectangular region 20. The eighth outer rectangular region 26 is tangent to the second outer edge 28. When viewed along a line perpendicular to the first end face 21, the short side of the eighth outer rectangular region 26 overlaps with the fourth imaginary line 94.

[0078] FIG. 8 is a schematic bottom view showing the measurement position of the dopant concentration on the second end face 22. As shown in FIG. 8, the second end face 22 includes a third center A3. The second end face 22 has a third central rectangular region 30, a ninth peripheral rectangular region 35, and a tenth peripheral rectangular region 36. The third central rectangular region 30, the ninth peripheral rectangular region 35, and the tenth peripheral rectangular region 36 are each a region where the dopant concentration is measured. When viewed along a line perpendicular to the second end face 22, the third central rectangular region 30, the ninth peripheral rectangular region 35, and the tenth peripheral rectangular region 36 each have a rectangular shape. The length of the short side of each of the third central rectangular region 30, the ninth peripheral rectangular region 35, and the tenth peripheral rectangular region 36 is, for example, 2 mm. The length of the long side of each of the third central rectangular region 30, the ninth peripheral rectangular region 35, and the tenth peripheral rectangular region 36 is, for example, 20 mm.

[0079] An imaginary line passing through the third center A3 and parallel to the first direction 101 is defined as a fifth imaginary line 95. An imaginary line passing through the third center A3 and parallel to the second direction 102 is defined as a sixth imaginary line 96. When viewed along a line perpendicular to the second end face 22, the third central rectangular region 30, the ninth outer peripheral rectangular region 35, and the tenth outer peripheral rectangular region 36 each lie in the second direction 102 with respect to the fifth imaginary line 95. When viewed along a line perpendicular to the second end face 22, the third central rectangular region 30, the ninth outer peripheral rectangular region 35, and the tenth outer peripheral rectangular region 36 each lie in the first direction 101 with respect to the sixth imaginary line 96.

[0080] When viewed along a line perpendicular to the second end face 22, a corner of the third central rectangular region 30 overlaps the third center A3. When viewed along a line perpendicular to the second end face 22, a short side of the third central rectangular region 30 overlaps the fifth imaginary line 95. When viewed along a line perpendicular to the second end face 22, a long side of the third central rectangular region 30 overlaps the sixth imaginary line 96.

[0081] The ninth outer rectangular region 35 is in the first direction 101 relative to the third central rectangular region 30. The ninth outer rectangular region 35 is tangent to the third outer edge 29. When viewed along a line perpendicular to the second end face 22, the short side of the ninth outer rectangular region 35 overlaps with the fifth imaginary line 95.

[0082] The tenth outer rectangular region 36 is in the second direction 102 relative to the third central rectangular region 30. The tenth outer rectangular region 36 is tangent to the third outer edge 29. When viewed along a line perpendicular to the second end face 22, the short side of the tenth outer rectangular region 36 overlaps the sixth imaginary line 96.

[0083] Next, a method for measuring the dopant concentration will be described. The dopant concentration is measured using the GDMS described above. GDMS is performed, for example, according to the procedure described above. Specifically, the InP single crystal 200 is cut along a plane perpendicular to the central axis of the cylindrical surface 23. This prepares a first wafer having a first end facet 21 and a second wafer having a second end facet 22. The configurations of the first and second wafers are substantially the same as the configuration of the InP single crystal substrate 100. The first end facet 21 of the first wafer corresponds to the first main surface 1. The second end facet 22 of the second wafer corresponds to the second main surface 2.

[0084] The first wafer is diced or scribed and then cleaved along the outer edges of the second central rectangular region 20, the seventh outer peripheral rectangular region 25, and the eighth outer peripheral rectangular region 26. The second wafer is diced or scribed and then cleaved along the outer edges of the third central rectangular region 30, the ninth outer peripheral rectangular region 35, and the tenth outer peripheral rectangular region 36. Thus, a pin-shaped cell is prepared. This pin-shaped cell is used as an ion source. The measurement conditions for GDMS can be, for example, the above-described measurement conditions. In this manner, the dopant concentration of the InP single crystal 200 is measured.

[0085] The dopant concentration in the second central rectangular region 20 is set to a third concentration. The third concentration is considered to be the dopant concentration at the second center A2 of the first end face 21. The third concentration is, for example, 1×10 １７ cm－３ 1x10 or more １９ cm －３ The following is the result.

[0086] The average value of the dopant concentration in the seventh peripheral rectangular region 25 and the dopant concentration in the eighth peripheral rectangular region 26 is set to a fourth concentration. The fourth concentration is considered to be the dopant concentration at the second outer edge 28 of the first end face 21. The fourth concentration is, for example, 1×10 １７ cm －３ 1x10 or more １９ cm －３ The following is the result.

[0087] The dopant concentration in the third central rectangular region 30 is set to a fifth concentration. The fifth concentration is considered to be the dopant concentration at the third center A3 of the second end face 22. The fifth concentration is, for example, 1.0×10 １６ cm －３ 5x10 or more １８ cm －３ The following is the result.

[0088] The average value of the dopant concentration in the ninth peripheral rectangular region 35 and the dopant concentration in the tenth peripheral rectangular region 36 is set to a sixth concentration. The sixth concentration is considered to be the dopant concentration at the third outer edge 29 of the second end face 22. The sixth concentration is, for example, 1.0×10 １６ cm －３ 5x10 or more １８ cm －３ The following is the result.

[0089] The fourth concentration is, for example, lower than the third concentration. The absolute value of the value obtained by subtracting the fourth concentration from the third concentration and dividing the result by the third concentration is set to the third value. The sixth concentration is, for example, lower than the fifth concentration. The absolute value of the value obtained by subtracting the sixth concentration from the fifth concentration and dividing the result by the fifth concentration is set to the fourth value. At least one of the third value and the fourth value is 11.9% or less.

[0090] The third value may be, for example, 0.1% or more, or 1% or more. The third value may be, for example, 10% or less, or 8% or less. The fourth value may be, for example, 0.1% or more, or 1% or more. The fourth value may be, for example, 10% or less, or 8% or less.

[0091] The dopant concentration at the first end face 21 may be higher than the dopant concentration at the second end face 22. Specifically, the third concentration may be higher than the fifth concentration. The fourth concentration may be higher than the sixth concentration.

[0092] <Dislocation Density in Indium Phosphide Single Crystal> Dislocations are present in the InP single crystal 200 according to this embodiment. The dislocation densities at the first end facets 21 and the second end facets 22 are measured using a method similar to the above-described method for measuring dislocation density at the first main surface 1. Specifically, similar to the above-described method for measuring the dopant concentration, the InP single crystal 200 is cut to prepare a first wafer having the first end facets 21 and a second wafer having the second end facets 22. The same measurement method as the above-described method for measuring dislocation density at the first main surface 1 is performed on the first end facets 21 of the first wafer and the second end facets 22 of the second wafer.

[0093] Similarly, the dislocation density at the second center A2 of the first end face 21 and the dislocation density at the third center A3 of the second end face 22 are each measured using a method similar to the above-described method for measuring the dislocation density (first density) at the first center A1 of the first main surface 1. Specifically, the dislocation density is measured in a region of each of the first end face 21 and the second end face 22 that corresponds to the above-described central square region 17.

[0094] Similarly, the dislocation density at the second outer edge 28 of the first end face 21 and the dislocation density at the third outer edge 29 of the second end face 22 are each measured using a method similar to the above-mentioned method for measuring the dislocation density (second density) at the first outer edge 8 of the first main surface 1. Specifically, on each of the first end face 21 and the second end face 22, the dislocation densities are measured in regions corresponding to the above-mentioned first peripheral rectangular region 11, second peripheral rectangular region 12, third peripheral rectangular region 13, and fourth peripheral rectangular region 14.

[0095] At least one of the dislocation density at the first end face 21 and the dislocation density at the second end face 22 is 90 cm －２ The dislocation density at the first end face 21 is, for example, 1 cm －２ It may be more than 10 cm －２ The dislocation density at the first end face 21 may be, for example, 85 cm －２ It may be less than 75 cm －２ It may be less than 65 cm －２ The dislocation density at the second end face 22 may be, for example, 1 cm －２ It may be more than 10 cm －２ The dislocation density at the second end face 22 may be, for example, 86 cm －２ It may be less than 82 cm －２ It may be the following:

[0096] <Indium phosphide single crystal substrate manufacturing apparatus> Next, the configuration of the growth apparatus 300 for the InP single crystal 200 according to this embodiment will be described. Fig. 9 is a cross-sectional schematic diagram showing the configuration of the growth apparatus 300 for the InP single crystal 200 according to this embodiment. As shown in Fig. 9, the growth apparatus 300 for the InP single crystal 200 mainly includes a crucible 40, a stirring member 50, a crucible support 60, a first shaft 55, a second shaft 56, and a heating element 48.

[0097] The crucible 40 is made of a material that can withstand the heat generated when melting the raw materials. Specifically, the crucible 40 is made of, for example, pyrolytic boron nitride (pBN). The crucible 40 has a cylindrical shape with a bottom. The central axis X of the crucible 40 extends along the third direction 103. The crucible 40 has a seed crystal accommodation portion 41, an increased diameter portion 42, and a straight body portion 43.

[0098] The seed crystal accommodating portion 41 has a cylindrical shape with a bottom. The seed crystal accommodating portion 41 is a portion where the seed crystal is placed. The seed crystal accommodating portion 41 is open toward the third direction 103. The seed crystal accommodating portion 41 has a bottom portion 41 a and an outer peripheral portion 41 b.

[0099] The bottom portion 41a constitutes the bottom of the crucible 40. The central axis X passes through the bottom portion 41a. The outer peripheral portion 41b is continuous with the bottom portion 41a. The outer peripheral portion 41b has an annular shape. The outer peripheral portion 41b surrounds the central axis X. The outer peripheral portion 41b is provided in the third direction 103 relative to the bottom portion 41a. When viewed in the third direction 103, the outer shape of the outer peripheral portion 41b is circular.

[0100] The increasing diameter portion 42 is continuous with the seed crystal accommodating portion 41. Specifically, the increasing diameter portion 42 is continuous with the outer peripheral portion 41b. The increasing diameter portion 42 is provided in the third direction 103 relative to the seed crystal accommodating portion 41. The increasing diameter portion 42 has an annular shape. The increasing diameter portion 42 surrounds the central axis X. The outer diameter of the increasing diameter portion 42 increases with increasing distance from the seed crystal accommodating portion 41 along the third direction 103. Similarly, the inner diameter of the increasing diameter portion 42 increases with increasing distance from the seed crystal accommodating portion 41 along the third direction 103.

[0101] The straight body portion 43 is continuous with the increased diameter portion 42. The straight body portion 43 is provided in the third direction 103 relative to the increased diameter portion 42. From another perspective, the straight body portion 43 is provided on the opposite side of the seed crystal accommodating portion 41 relative to the increased diameter portion 42. The shape of the straight body portion 43 is annular. When viewed in the third direction 103, the outer shape of the straight body portion 43 is circular. The straight body portion 43 surrounds the central axis X. The inner diameter D of the straight body portion 43 is, for example, 150 mm or more and 200 mm or less.

[0102] The heating element 48 heats the crucible 40. Specifically, for example, when power is supplied to the heating element 48, the heating element 48 heats the crucible 40. The heating element 48 has a cylindrical shape. The heating element 48 surrounds the crucible 40. The heating element 48 is spaced apart from the crucible 40. The heating element 48 has, for example, a first heating element portion 48a, a second heating element portion 48b, and a third heating element portion 48c. The second heating element portion 48b is provided in a fourth direction 104 relative to the first heating element portion 48a. The third heating element portion 48c is provided in the fourth direction 104 relative to the second heating element portion 48b. The fourth direction 104 is a direction opposite to the third direction 103. The growth apparatus 300 is configured so that the power supplied to each of the first heating element 48a, the second heating element 48b, and the third heating element 48c can be controlled individually.

[0103] The crucible support 60 supports the crucible 40. The crucible support 60 is disposed in the fourth direction 104 relative to the crucible 40. The first shaft 55 is attached to the crucible support 60. The first shaft 55 is disposed in the fourth direction 104 relative to the crucible support 60. The first shaft 55 extends along the third direction 103. The central axis of the first shaft 55 substantially overlaps with the central axis X. The first shaft 55 is configured to be rotatable around the central axis X. From another perspective, the crucible 40 is configured to be rotatable around the central axis X. The first shaft 55 is configured to be movable along a direction parallel to the third direction 103. From another perspective, the crucible 40 is configured to be movable along a direction parallel to the third direction 103.

[0104] As shown in FIG. 9 , the stirring member 50 is disposed inside the crucible 40. The stirring member 50 is surrounded by the cylindrical portion 43. The stirring member 50 has, for example, a main body portion 57 and four blade portions 70. The main body portion 57 extends along the third direction 103. The central axis of the main body portion 57 substantially overlaps with the central axis X. The main body portion 57 is configured to be rotatable around the central axis X. From another perspective, the rotation axis of the main body portion 57 substantially overlaps with the central axis X. Hereinafter, the central axis X will also be referred to as the rotation axis X. The shape of the main body portion 57 is, for example, a quadrangular prism. The main body portion 57 is made of, for example, quartz or carbon covered with pBN.

[0105] Fig. 10 is a schematic bottom view showing the configuration of the agitating member 50. Fig. 10 shows the configuration of the agitating member 50 as viewed in a third direction 103. As shown in Figs. 9 and 10, each of the four blades 70 is attached to the main body 57. Each of the four blades 70 is made of quartz or carbon covered with pBN. The four blades 70 include a first blade 71, a second blade 72, a third blade 73, and a fourth blade 74.

[0106] 9 and 10 , each of the four blade portions 70 extends along a radial direction perpendicular to the rotation axis X of the main body portion 57. The radial direction is perpendicular to the rotation axis X of the main body portion 57 and is a direction from the rotation axis X toward the crucible 40. When viewed in the third direction 103, each of the four blade portions 70 extends radially from the rotation axis X. Specifically, the extension direction of the first blade portion 71 is, for example, substantially parallel to the extension direction of the second blade portion 72. The extension direction of the third blade portion 73 is, for example, substantially parallel to the extension direction of the fourth blade portion 74. The extension direction of the third blade portion 73 is, for example, substantially perpendicular to the extension direction of the first blade portion 71.

[0107] The main body portion 57 is provided between the first blade portion 71 and the second blade portion 72. The main body portion 57 is provided between the third blade portion 73 and the fourth blade portion 74. The first blade portion 71 is spaced apart from the second blade portion 72. The third blade portion 73 is spaced apart from the fourth blade portion 74.

[0108] The thickness B1 of each of the four wing portions 70 in the third direction 103 is, for example, 5 mm. The thickness B1 may be, for example, 3 mm or more and 10 mm or less. The thickness B1 may be, for example, 5 mm or more, 7 mm or more, or 8 mm or more. The thickness B1 may be, for example, 9 mm or less, 8 mm or less, or 7 mm or less.

[0109] The length B2 of each of the four blade portions 70 in the radial direction is, for example, 10 mm or more and 70 mm or less. The length B2 may be, for example, 20 mm or more, or 30 mm or more. The length B2 may be, for example, 100 mm or less, or 50 mm or less.

[0110] The width B3 of each of the four blade portions 70 in a direction perpendicular to the radial direction is, for example, 5 mm. Width B3 may be, for example, 3 mm or more and 10 mm or less. The distance between the first blade portion 71 and the second blade portion 72 in the direction in which the first blade portion 71 extends may be, for example, substantially the same as width B3. The distance between the third blade portion 73 and the fourth blade portion 74 in the direction in which the third blade portion 73 extends may be, for example, substantially the same as width B3.

[0111] The second shaft 56 is attached to the main body 57. The second shaft 56 is provided in the third direction 103 relative to the main body 57. The second shaft 56 extends along the third direction 103. The central axis of the second shaft 56 substantially overlaps with the central axis X. The second shaft 56 is configured to be rotatable around the central axis X. From another perspective, the rotation of the second shaft 56 causes the stirring member 50 to rotate around the central axis X. The second shaft 56 is configured to be movable along a direction parallel to the third direction 103. From another perspective, the stirring member 50 is configured to be movable along a direction parallel to the third direction 103.

[0112] <Method for Manufacturing Indium Phosphide Single Crystal> Next, a method for manufacturing the InP single crystal 200 according to this embodiment will be described. The InP single crystal 200 is manufactured using a vertical boat method. The vertical boat method includes, for example, the vertical Bridgman (VB) method, the vertical gradient freeze (VGF) method, and a hybrid method that combines the VB method and the VGF method.

[0113] 11 is a flow chart schematically showing a method for producing an InP single crystal 200 according to this embodiment. As shown in Fig. 11, the method for producing an InP single crystal 200 according to this embodiment mainly includes a step (S10) of preparing a growth apparatus, a step (S20) of arranging a seed crystal, a step (S30) of arranging an indium phosphide source material and a sealing material, a step (S40) of melting the source material, a step (S50) of inserting a stirring member into the indium phosphide melt, a step (S60) of growing the crystal, and a step (S70) of cutting the crystal.

[0114] First, a step (S10) of preparing a growth apparatus is performed. Fig. 12 is a partial cross-sectional schematic diagram showing the step (S10) of preparing a growth apparatus 300. As shown in Fig. 12, the growth apparatus 300 according to this embodiment is prepared. In the step (S10) of preparing a growth apparatus, the stirring member 50 is disposed outside the crucible 40. For ease of explanation, the stirring member 50 and the second shaft 56 are not shown in Fig. 12.

[0115] Next, the step of placing a seed crystal (S20) is performed. Fig. 13 is a cross-sectional schematic diagram showing a crucible in which a seed crystal 84, an indium phosphide source material 85, and a sealing material 86 are placed. As shown in Fig. 13, in the step of placing a seed crystal (S20), the seed crystal 84 is placed inside the seed crystal accommodation portion 41. The seed crystal 84 is made of single-crystal indium phosphide. The seed crystal 84 may contain any one of sulfur, iron, and tin as an impurity atom.

[0116] Next, a step (S30) of arranging indium phosphide source materials and a sealing material is performed. As shown in FIG. 13 , a plurality of indium phosphide source materials 85 (hereinafter also referred to as InP source materials 85) are arranged on a seed crystal 84. Each of the plurality of InP source materials 85 is made of, for example, polycrystalline indium phosphide. Each of the plurality of InP source materials 85 has, for example, a cylindrical shape. The plurality of InP source materials 85 are stacked on the seed crystal 84. The plurality of InP source materials 85 weigh, for example, 16 kg. One of sulfur, iron, and tin is arranged inside the crucible 40 as an impurity.

[0117] Next, a sealing material 86 is placed on the plurality of InP raw materials 85. The sealing material 86 is, for example, boron oxide (B ２ O ３ The sealing material 86 is cylindrical in shape. The weight of the sealing material 86 is, for example, 2850 g.

[0118] Next, the step of melting the raw material (S40) is performed. The crucible 40 is heated by supplying current to the heating element 48. The current supplied to the first heating element 48a is greater than the current supplied to the second heating element 48b. The current supplied to the second heating element 48b is greater than the current supplied to the third heating element 48c. Therefore, the temperature of the crucible 40 increases with increasing distance from the bottom 41a along the third direction 103. This causes a portion of the seed crystal 84 and the InP raw material 85 to melt.

[0119] 14 is a cross-sectional view schematically illustrating the step (S40) of melting the raw material. As shown in FIG. 14 , a portion of the melted seed crystal 84 and the melted InP raw material 85 become an indium phosphide melt 87 (hereinafter also referred to as an InP melt 87). This prepares the InP melt 87. The InP melt 87 comes into contact with the remaining portion of the seed crystal 84. The melting of the sealant 86 turns the sealant 86 into a liquid sealant 88. The liquid sealant 88 covers the InP melt 87.

[0120] Next, the step (S50) of inserting the stirring member into the indium phosphide melt is performed. FIG. 15 is a cross-sectional schematic diagram illustrating the step (S50) of inserting the stirring member into the indium phosphide melt. As shown in FIG. 15 , the stirring member 50 is moved along the fourth direction 104 using the second shaft 56, thereby inserting the stirring member 50 into the InP melt 87 inside the crucible 40. The four blade portions 70 are positioned in the fourth direction 104 relative to the body portion 43. The four blade portions 70 are surrounded by the increased diameter portion 42. The second shaft 56 is positioned in the third direction 103 relative to the body portion 43. The stirring member 50 is positioned in the third direction 103 relative to the seed crystal 84. The four blade portions 70 are positioned inside the InP melt 87. A portion of the main body portion 57 is positioned in the third direction 103 relative to the liquid sealant 88.

[0121] When viewed along third direction 103, each of the four blade portions 70 is disposed inside crucible 40 such that, for example, the extension direction of each of the four blade portions 70 is substantially parallel to the <011> direction of seed crystal 84. When viewed along third direction 103, for example, each of the four blade portions 70 is disposed in the <011> direction of seed crystal 84 with respect to rotation axis X. Specifically, when viewed along third direction 103, first blade portion 71, second blade portion 72, third blade portion 73, and fourth blade portion 74 are disposed in the

[011] direction of seed crystal 84, the [0-1-1] direction of seed crystal 84, the [0-11] direction of seed crystal 84, and the [01-1] direction of seed crystal 84, respectively, with respect to rotation axis X.

[0122] Next, the crystal growing step (S60) is performed. First, stirring of InP melt 87 is started using stirring member 50. Fig. 16 is a bottom view schematic diagram showing the operation of stirring member 50 in the crystal growing step (S60). Fig. 17 is a schematic diagram showing the relationship between the tilt angle of blade portion 70 with respect to the <011> direction and time.

[0123] 17, the horizontal axis represents time, and the vertical axis represents the tilt angle of the extension direction of wing portion 70 relative to the <011> direction. The tilt angle of the extension direction of wing portion 70 relative to the <011> direction is the tilt angle of imaginary line 99 (see FIG. 16 ), which passes through rotation axis X and is parallel to the extension direction of wing portion 70, relative to the <011> direction when viewed in third direction 103. In FIG. 17, a tilt angle of 0° indicates that the extension direction of wing portion 70 is parallel to the <011> direction.

[0124] 16 and 17 , the four blade portions 70 repeatedly reciprocate along the rotation direction C of the main body portion 57. From another perspective, when viewed along the third direction 103, the four blade portions 70 alternately repeat rotational movement along the clockwise direction and rotational movement along the counterclockwise direction.

[0125] 17 , the blade portion 70 periodically repeats a reciprocating motion along the rotation direction C. The period T of the reciprocating motion is, for example, not less than 60 seconds and not more than 300 seconds. The period T may be, for example, not less than 80 seconds, or not less than 100 seconds. The period T may be, for example, not more than 220 seconds, or not more than 140 seconds.

[0126] The angular amplitude F of the reciprocating motion is, for example, 10° or more and 45° or less. The angular amplitude F may be, for example, 15° or more, 20° or more, 30° or more, or 40° or more. The angular amplitude F may be, for example, 60° or less, or 50° or less. Note that the angular amplitude F is the sum of the maximum tilt angle when the extension direction of the wing portions 70 is tilted clockwise with respect to the <011> direction of the seed crystal 84 during the reciprocating motion, and the maximum tilt angle when the extension direction of the wing portions 70 is tilted counterclockwise with respect to the <011> direction of the seed crystal 84.

[0127] During the reciprocating motion, a state occurs multiple times in which blade portion 70 faces the <011> direction of seed crystal 84. Specifically, during the reciprocating motion, a state occurs multiple times in which the extending direction of blade portion 70 is parallel to the <011> direction of seed crystal 84. When viewed in third direction 103, blade portion 70 repeats reciprocating motion along rotation direction C, for example, with the <011> direction of seed crystal 84 as the center.

[0128] 18 is a cross-sectional schematic diagram showing the step (S60) of growing a crystal. As shown in FIG. 18 , after a predetermined time has elapsed since stirring of InP melt 87 using stirring member 50 began, crucible 40 is moved along fourth direction 104 while stirring InP melt 87 using stirring member 50. This reduces the temperature of the portion of InP melt 87 close to the remainder of seed crystal 84. The moving speed of crucible 40 in fourth direction 104 is, for example, 2.0 mm / hour or more and 5.0 mm / hour or less. InP melt 87 in contact with the remainder of seed crystal 84 solidifies, thereby growing indium phosphide crystal 210 (hereinafter also referred to as InP crystal 210).

[0129] The time (stirring time) from when stirring of the InP melt 87 using the stirring member 50 starts until the movement of the crucible 40 starts is, for example, not less than 1 hour and not more than 10 hours. From when stirring of the InP melt 87 using the stirring member 50 starts until the stirring time has elapsed, the crucible 40 is, for example, stationary.

[0130] In the crystal growing step (S60), an interface (solid-liquid interface I) between the InP crystal 210 and the InP melt 87 is formed. The shape of the solid-liquid interface I is convex in the third direction 103. The longest distance between two different points on the solid-liquid interface I in the third direction 103 is the height H of the solid-liquid interface I. The value obtained by dividing the height H by the inner diameter D (the convexity) is, for example, 2%. The convexity may be, for example, 0% or more and less than 3%. If the convexity is excessively large, the InP melt 87 closer to the central axis X solidifies excessively quickly compared to the InP melt 87 farther from the central axis X. In this case, dopant segregation occurs, increasing the variation in the dopant concentration in the InP single crystal 200. By setting the convexity to less than 3%, the variation in the dopant concentration in the InP single crystal 200 can be reduced. Furthermore, by making the degree of convexity less than 3% through the soaking effect of stirring the melt, the dislocation density in the InP single crystal 200 can be reduced.

[0131] The shortest distance E between the solid-liquid interface I and the four wing portions 70 in the third direction 103 is, for example, 5 mm or more and 20 mm or less. The shortest distance E may be, for example, 6 mm or more, or 10 mm or more. The shortest distance E may be, for example, 15 mm or less, or 12 mm or less.

[0132] As the crucible 40 continues to move, the InP melt 87 inside the crucible 40 solidifies. In this way, the InP crystal 210 is produced. The maximum diameter of the InP crystal 210 is substantially the same as the inner diameter D of the body portion 43.

[0133] Next, a crystal cutting step (S70) is carried out. For example, the InP crystal 210 is cut using a wire saw to produce an InP single crystal 200 (see FIGS. 5 and 6). Note that in the crystal cutting step (S70), the InP crystal 210 may be cut to produce an InP single crystal substrate 100 (see FIGS. 1 and 2).

[0134] Next, the effects of the InP single crystal substrate 100, the InP single crystal 200, and the method for manufacturing the InP single crystal 200 according to the present disclosure will be described.

[0135] The dislocation density and dopant concentration in the InP single crystal substrate 100 affect the yield of semiconductor devices manufactured using the InP single crystal substrate 100. Specifically, when semiconductor devices such as optical sensors are manufactured using the InP single crystal substrate 100, the dark current of semiconductor devices manufactured using an InP single crystal substrate 100 with an excessively high dislocation density may be excessively large. In this case, the signal-to-noise ratio (SN ratio) may deteriorate. As a result, the yield of semiconductor devices decreases. If the dopant concentration on the primary surface of the InP single crystal substrate 100 varies excessively, the characteristics of semiconductor devices manufactured using the InP single crystal substrate 100 will vary greatly. As a result, the yield of semiconductor devices will decrease.

[0136] The inventors investigated ways to improve the yield of semiconductor devices and found the following. Specifically, the inventors focused on the temperature distribution of the InP melt 87 during the growth of the InP single crystal 200. Specifically, during the growth of the InP single crystal 200, temperature variations in the InP melt 87 may occur within a plane perpendicular to the growth direction. In this case, solidification begins in the lower-temperature portions of the InP melt 87, causing dopants to segregate in the InP single crystal 200. This results in excessively large variations in the dopant concentration in the InP single crystal 200. Furthermore, excessively large temperature fluctuations in the InP melt 87 are likely to result in twinning, reducing the single crystal yield. In this case, if growth is performed under conditions with a large temperature gradient to suppress twinning due to temperature fluctuations, the dislocation density in the InP single crystal 200 increases.

[0137] In the process of growing an InP single crystal, dislocation density can be reduced by reducing the degree of convexity of the InP melt 87. In this case, twins may be more likely to occur in the InP crystal 210. The inventors have noticed that twins are more likely to occur from the outer facet portion of the InP crystal 210. Specifically, twins are more likely to occur when the degree of supercooling of the InP melt 87 becomes excessively large due to the occurrence of constitutional supercooling of the InP melt 87 near the facet portion. Based on the above findings, the inventors have come up with the idea of ​​stirring the InP melt 87 near the <011> direction in which the outer facet portion occurs.

[0138] According to the manufacturing method of the InP single crystal 200 of this embodiment, in the crystal growing step (S60), the wing portion 70 repeatedly reciprocates along the rotation direction C of the main body portion 57. During the reciprocating motion, the wing portion 70 repeatedly faces the <011> direction of the seed crystal 84. When the direction of movement of the wing portion 70 reverses during the reciprocating motion, the InP melt 87 near the wing portion 70 is effectively stirred. Therefore, the InP melt 87 near the <011> direction of the InP crystal 210 can be sufficiently stirred using the stirring member 50. This reduces the degree of supercooling near the outer peripheral facet of the InP crystal 210. Furthermore, stirring the InP melt 87 reduces temperature variations in the InP melt 87. This reduces the dopant concentration variations and dislocation density in the InP single crystal 200 while suppressing the occurrence of twins. As a result, the yield of semiconductor devices can be improved.

[0139] If the angular amplitude F of the wing portions 70 during the reciprocating motion is excessively small, it will be impossible to sufficiently stir the InP melt 87. According to the method for producing the InP single crystal 200 according to this embodiment, the angular amplitude F of the wing portions 70 during the reciprocating motion is 10° or greater. Therefore, the InP melt 87 can be sufficiently stirred by the reciprocating motion of the wing portions 70.

[0140] According to the method for producing the InP single crystal 200 of this embodiment, the stirring member 50 has four blade portions 70. Therefore, the InP melt 87 can be stirred more effectively using the stirring member 50. This makes it possible to reduce both the variation in dopant concentration and the dislocation density in the InP single crystal 200.

[0141] According to the method for manufacturing the InP single crystal 200 of this embodiment, the period T of the reciprocating motion is 60 seconds or more. Therefore, compared to when the period T is excessively short, the reaction force that the wing portion 70 receives from the InP melt 87 can be reduced. This allows the life of the wing portion 70 to be extended.

[0142] According to the method for producing the InP single crystal 200 of this embodiment, the period T of the reciprocating motion is 300 seconds or less, which allows the InP melt 87 to be stirred more effectively than when the period T is excessively long.

[0143] According to the method for manufacturing InP single crystal 200 of this embodiment, thickness B1 of wing portion 70 in the direction along rotation axis X of main body portion 57 is 3 mm or more. This allows for more effective stirring of InP melt 87 compared to when wing portion 70 is excessively thin. According to the method for manufacturing InP single crystal 200 of this embodiment, thickness B1 of wing portion 70 in the direction along rotation axis X of main body portion 57 is 10 mm or less. This allows for a reduction in the reaction force that wing portion 70 receives from InP melt 87 compared to when wing portion 70 is excessively thick. This allows for a longer lifespan of wing portion 70.

[0144] According to the method for manufacturing InP single crystal 200 of this embodiment, length B2 of wing portion 70 in the radial direction is 10 mm or more. This allows for more effective stirring of InP melt 87 compared to when wing portion 70 is excessively short. According to the method for manufacturing InP single crystal 200 of this embodiment, length B2 of wing portion 70 in the radial direction is 70 mm or less. This allows for a reduction in the reaction force that wing portion 70 receives from InP melt 87 compared to when wing portion 70 is excessively long. This allows for a longer lifespan of wing portion 70.

[0145] According to the method for manufacturing the InP single crystal 200 of this embodiment, the shortest distance E between the wing portion 70 and the solid-liquid interface I in the direction of extension of the rotation axis X of the main body portion 57 is 20 mm or less. This makes it possible to effectively stir the portion of the InP melt 87 close to the solid-liquid interface I. This allows the degree of supercooling to be further reduced near the outer peripheral facet of the InP crystal 210.

[0146] According to the method for manufacturing the InP single crystal 200 of this embodiment, the wing portion 70 is made of quartz or carbon covered with pBN, and therefore can withstand the heat applied when the indium phosphide melt 87 is kept in a molten state.

[0147] According to the InP single crystal substrate 100 of this embodiment, the dislocation density on the first main surface 1 is 90 cm －２ The absolute value of the difference between the first concentration and the second concentration divided by the first concentration is 11.9% or less. In this way, the dislocation density in the first main surface 1 is sufficiently reduced, and the variation in the dopant concentration in the first main surface 1 is also sufficiently reduced. This makes it possible to improve the yield of semiconductor devices manufactured using the InP single crystal substrate 100.

[0148] In the InP single crystal substrate 100 according to this embodiment, the value obtained by dividing the second density by the first density is less than 203%. In this manner, the variation in dislocation density in the first main surface 1 is sufficiently reduced. This allows for an improvement in the yield of semiconductor devices manufactured using the InP single crystal substrate 100.

[0149] In the InP single crystal substrate 100 according to this embodiment, the diameter of the first main surface 1 is 150 mm or more. Thus, even when the InP single crystal substrate 100 has a large diameter, the dislocation density in the first main surface 1 is sufficiently reduced, and the variation in dopant concentration in the first main surface 1 is also sufficiently reduced. This allows for a further improvement in the yield of semiconductor devices manufactured using the InP single crystal substrate 100.

[0150] According to the InP single crystal substrate 100 of this embodiment, the first main surface 1 is a {100} plane. From another perspective, the growth direction of the InP single crystal substrate 100 is the <100> direction. When the growth direction is the <100> direction, twins are more likely to occur in the InP single crystal than when the growth direction is the <111> direction. According to the InP single crystal substrate 100 of this embodiment, the occurrence of twins is suppressed even when the growth direction is the <100> direction.

[0151] In the InP single crystal 200 according to this embodiment, at least one of the dislocation density at the first end facet 21 and the dislocation density at the second end facet 22 is 90 cm －２ At least one of the absolute value of the value obtained by subtracting the fourth concentration from the third concentration and dividing it by the third concentration, and the absolute value of the value obtained by subtracting the sixth concentration from the fifth concentration and dividing it by the fifth concentration, is 11.9% or less. In this way, the dislocation density is sufficiently reduced, and the variation in dopant concentration at at least one of the first end facet 21 and the second end facet 22 is sufficiently reduced. This allows for an improvement in the yield of semiconductor devices manufactured using the InP single crystal 200.

[0152] (Modification) Next, a modification of the method for manufacturing an InP single crystal 200 according to this embodiment will be described. Fig. 19 is a partial cross-sectional schematic diagram showing the configuration of a growth apparatus 300 for an InP single crystal 200 according to this modification. Fig. 20 is a bottom schematic diagram showing the configuration of a stirring member 50 according to this modification. As shown in Figs. 19 and 20 , a main body 57 may have a rod-shaped member 58 and a disk member 59.

[0153] The rod-shaped member 58 is attached to the second shaft 56. The rod-shaped member 58 extends along the third direction 103. The rod-shaped member 58 has, for example, a rectangular prism shape. The disk member 59 is attached to the rod-shaped member 58. The disk member 59 is provided in the fourth direction 104 relative to the rod-shaped member 58. The disk member 59 extends in the radial direction. The central axis of the disk member 59 substantially overlaps with the central axis X.

[0154] 20 , four blade portions 70 are attached to the disk member 59. The four blade portions 70 may be spaced apart from one another. When viewed in the third direction 103, the four blade portions 70 are provided, for example, inside the outer edge of the disk member 59. The diameter of the disk member 59 (third diameter W3) is, for example, 100 mm. The third diameter W3 may be, for example, not less than 120 mm and not more than 146 mm.

[0155] By attaching the wing portion 70 to the disk member 59, it is possible to increase the contact area between the wing portion 70 and the main body portion 57. This increases the strength of the wing portion 70. As a result, it is possible to extend the life of the wing portion 70.

[0156] Although the above description has been given of a configuration in which the number of blade portions 70 is four, the method for manufacturing InP single crystal 200 according to the present disclosure is not limited to the above configuration. Specifically, the number of blade portion 70 may be one. In other words, it is sufficient for stirring member 50 to have at least one blade portion 70. Specifically, it is sufficient for stirring member 50 to have at least one of, for example, first blade portion 71, second blade portion 72, third blade portion 73, or fourth blade portion 74. The number of blade portions 70 may be two or more, or five or more.

[0157] In the crystal growing step (S60), the crucible 40 may repeatedly reciprocate along the rotation direction C of the main body 57. Specifically, both the stirring member 50 and the crucible 40 may reciprocate. The reciprocating motion of the blade 70 does not have to be periodic. Specifically, for example, the angular amplitude F of the reciprocating motion may change over time. For example, the period T of the reciprocating motion may change over time.

[0158] <Sample Preparation> First, InP single crystals 200 according to Samples 1 to 11 were prepared. The InP single crystal 200 according to Sample 1 was used as a comparative example. The InP single crystals 200 according to Samples 2 to 11 were used as examples. The InP single crystals 200 according to Samples 1 to 11 were manufactured according to the above-mentioned method for manufacturing the InP single crystal 200. Specifically, the InP single crystals 200 were manufactured using the conditions shown in Table 1 below.

[0159]

[0160] Table 1 shows the manufacturing conditions for the InP single crystal 200 for Samples 1 to 11. In the "Configuration of Stirring Member" column of Table 1, "A" indicates that the stirring member 50 according to the present embodiment described above (see FIGS. 9 and 10) was used. Specifically, the stirring member 50 had a main body 57 and four blades 70. Each of the four blades 70 was attached to the main body 57. The main body 57 did not have a disk member 59.

[0161] In the "Configuration of Stirring Member" column of Table 1, "B" indicates that the stirring member 50 according to the above-described modified example of this embodiment (see FIGS. 19 and 20) was used. Specifically, the main body 57 had a disk member 59. The four blades 70 were attached to the disk member 59.

[0162] As shown in Table 1, no stirring member 50 was used in Sample 1. The stirring member 50 according to this embodiment was used in Samples 2 and 4 to 6. The stirring member 50 according to a modified example of this embodiment was used in Samples 3 and 7 to 11.

[0163] In Samples 2 to 11, the period T of the reciprocating motion was set to 60 seconds or more and 480 seconds or less. The angular amplitude F of the reciprocating motion was set to 15 degrees or more and 45 degrees or less. In Samples 1 to 9, the dopant was sulfur. In Sample 10, the dopant was iron. In Sample 11, the dopant was tin.

[0164] In Samples 1 to 11, the inner diameter D of the crucible 40 was 156 mm. The weight of the InP source material 85 was 16 kg. The weight of the sealing material 86 was 2850 g. In the crystal growing step (S60), the moving speed of the crucible 40 in the fourth direction 104 was 2.5 mm / hour. In Samples 2 to 11, the thickness B1 of each of the four wing portions 70 was 5 mm. The length B2 of each of the four wing portions 70 was 45 mm. The width B3 of each of the four wing portions 70 was 5 mm.

[0165] <Experimental Method> The presence or absence of twins was confirmed for the InP single crystals 200 of Samples 1 to 11. Using the dopant concentration measurement method described above, the dopant concentrations at the first end facet 21 and the second end facet 22 were measured. Specifically, for the first end facet 21, the dopant concentration at the second center A2 (third concentration) and the dopant concentration at the second outer edge 28 (fourth concentration) were measured. The absolute value of the value obtained by subtracting the fourth concentration from the third concentration and dividing the result by the third concentration (third value) was calculated. For the second end facet 22, the dopant concentration at the third center A3 (fifth concentration) and the dopant concentration at the third outer edge 29 (sixth concentration) were measured. The absolute value of the value obtained by subtracting the sixth concentration from the fifth concentration and dividing the result by the fifth concentration (fourth value) was calculated. GDMS was used to measure the dopant concentrations. The measurement conditions described above were used for GDMS.

[0166] For Samples 1 to 11, the dislocation density at the first end face 21 and the dislocation density at the second end face 22 were measured using the dislocation density measurement method described above. The first density described above was measured for each of the first end face 21 and the second end face 22. Specifically, the dislocation density was measured in a region corresponding to the central square region 17 described above for each of the first end face 21 and the second end face 22.

[0167] The third density described above was measured on each of the first end face 21 and the second end face 22. Specifically, the dislocation density was measured on each of the first end face 21 and the second end face 22 in regions corresponding to the first peripheral rectangular region 11 and the second peripheral rectangular region 12 described above.

[0168] The fourth density described above was measured at each of the first end face 21 and the second end face 22. Specifically, the dislocation densities were measured at each of the first end face 21 and the second end face 22 in regions corresponding to the third peripheral rectangular region 13 and the fourth peripheral rectangular region 14 described above. The first density, the third density, and the fourth density were used to calculate the second values ​​A and B described above at each of the first end face 21 and the second end face 22.

[0169]

[0170] Table 2 shows the measurement results of the presence or absence of twins and the dopant concentration in the InP single crystal 200 according to samples 1 to 11. As shown in Table 2, twins occurred in sample 1. No twins occurred in samples 2 to 11. From the above, it was confirmed that the method for manufacturing the InP single crystal 200 according to the example can suppress the occurrence of twins, compared to the method for manufacturing the InP single crystal 200 according to the comparative example.

[0171] As shown in Table 2, the fourth value was 7.5% or more and 15% or less in Samples 2 to 11. In the samples (Samples 4 to 11) in which the period T of the reciprocating motion was 60 seconds or more and 300 seconds or less, the fourth value was 9.5% or less.

[0172] The third value was 12.5% ​​in Sample 1. The third value was 6.3% or more and 11.9% or less in Samples 2 to 11. The third value was 9.8% or less in the samples (Samples 4 to 11) in which the period T of the reciprocating motion was 60 seconds or more and 300 seconds or less.

[0173] From the above, it was confirmed that, compared to the method for manufacturing the InP single crystal 200 according to the comparative example, the method for manufacturing the InP single crystal 200 according to the example can reduce the variation in the dopant concentration at the first end facet 21. Furthermore, it was confirmed that when the period T of the reciprocating motion is 60 seconds or more and 300 seconds or less, the variation in the dopant concentration at each of the first end facet 21 and the second end facet 22 can be reduced.

[0174]

[0175] Table 3 shows the results of measuring the dislocation density in the InP single crystal 200 of Samples 1 to 11. As shown in Table 3, in Sample 1, the dislocation density at the second end facet 22 was 150 cm －２ The dislocation density at the first end face 21 was 100 cm －２ In samples 2 to 11, the dislocation density at the second end face 22 was 80 cm －２ More than 90cm －２ The dislocation density at the first end face 21 was 60 cm－２ 80cm or more －２ It was as follows.

[0176] From the above, it was confirmed that the method for manufacturing the InP single crystal 200 according to the example can reduce the dislocation density at each of the first end face 21 and the second end face 22, compared to the method for manufacturing the InP single crystal 200 according to the comparative example.

[0177] In Sample 1, the second value A at the second end face 22 was 200%. In Samples 2 to 11, the second value A at the second end face 22 was 84% ​​or more and 192% or less. In Samples 3 to 11, the second value A at the second end face 22 was 84% ​​or more and 98% or less. In Samples 2 to 11, the second value A at the first end face 21 was 188% or more and 202% or less.

[0178] In Samples 1 to 11, the second value B at the second end surface 22 was 85% or more and 118% or less. In Samples 1 to 10, the second value B at the second end surface 22 was 85% or more and 110% or less. In Samples 1 to 13, the second value B at the first end surface 21 was 100% or more and 113% or less.

[0179] From the above, it was confirmed that, compared to the method for manufacturing an InP single crystal 200 according to the comparative example, the method for manufacturing an InP single crystal 200 according to the example can reduce both the variation in dopant concentration and the dislocation density while suppressing the occurrence of twins.

[0180] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above description, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0181] 1 First main surface, 2 Second main surface, 3 Outer peripheral surface, 5 Square region, 8 First outer edge, 10 First central rectangular region, 11 First outer peripheral rectangular region, 12 Second outer peripheral rectangular region, 13 Third outer peripheral rectangular region, 14 Fourth outer peripheral rectangular region, 15 Fifth outer peripheral rectangular region, 16 Sixth outer peripheral rectangular region, 17 Central square region, 18 Outer peripheral region, 19 Central region, 20 Second central rectangular region, 21 First end face, 22 Second end face, 23 Cylindrical surface, 25 Seventh outer peripheral rectangular region, 26 Eighth outer peripheral rectangular region, 28 Second outer edge, 29 Third outer edge, 30 Third central rectangular region, 35 Ninth outer peripheral rectangular region, 36 Tenth outer peripheral rectangular region, 40 Crucible, 41 Seed crystal accommodating portion, 41a Bottom, 41b Outer peripheral portion, 42 Increasing diameter portion, 43 Straight body portion, 48 Heating element, 48a First heating element portion, 48b Second heating element portion, 48c Third heating element portion, 50 Stirring member, 55 First shaft, 56 Second shaft, 57 Main body portion, 58 Rod-shaped member, 59 Disk member, 60 Crucible support portion, 70 Blade portion, 71 First blade portion, 72 Second blade portion, 73 Third blade portion, 74 Fourth blade portion, 84 Seed crystal, 85 Indium phosphide raw material, 86 Sealing material, 87 Indium phosphide melt, 88 Liquid sealing material, 91 First imaginary line, 92 Second imaginary line, 93 Third imaginary line, 94 Fourth imaginary line, 95 Fifth imaginary line, 96 Sixth imaginary line, 99 Imaginary line, 100 Indium phosphide single crystal substrate, 101 First direction, 102 Second direction, 103 Third direction, 104 Fourth direction, 200 Indium phosphide single crystal, 210 Indium phosphide crystal, 300 Growth apparatus, A1 First center, A2 Second center, A3 Third center, B1 Thickness, B2 Length, B3 Width, C Rotation direction, D Inner diameter, E Shortest distance, F Angle amplitude, H Height, I Solid-liquid interface, L1 First length, L2 Second length, O Center, R Radius, T Period, W1 First diameter, W2 Second diameter, W3 Third diameter, X Central axis (rotation axis).

Claims

1. It has a main surface, contains a dopant, the diameter of the main surface is 150 mm or more and 160 mm or less, the dislocation density on the main surface is 90 cm －２ or less, when the concentration of the dopant at the center of the main surface is defined as the first concentration and the concentration of the dopant at the outer edge of the main surface is defined as the second concentration, the value obtained by dividing the absolute value of the difference between the first concentration and the second concentration by the first concentration is 11.9% or less. An indium phosphide single crystal substrate.

2. The main surface includes a central square region that contains the center of the main surface and has a side length of 40 mm, and a first outer peripheral rectangular region, a second outer peripheral rectangular region, a third outer peripheral rectangular region, and a fourth outer peripheral rectangular region that are respectively in the [011] direction, [0-1-1] direction, [01-1] direction, and [0-11] direction with respect to the central square region. The length of the short side of each of the first outer peripheral rectangular region, the second outer peripheral rectangular region, the third outer peripheral rectangular region, and the fourth outer peripheral rectangular region is 20 mm. The length of the long side of each of the first outer peripheral rectangular region, the second outer peripheral rectangular region, the third outer peripheral rectangular region, and the fourth outer peripheral rectangular region is 40 mm. When the distance between each outer peripheral end of the first outer peripheral rectangular region, the second outer peripheral rectangular region, the third outer peripheral rectangular region, and the fourth outer peripheral rectangular region and the center of the main surface is a first numerical value, and the radius of the main surface is a second numerical value, and the unit of each of the first numerical value and the second numerical value is mm, the first numerical value is a value obtained by multiplying the integer value obtained by truncating the decimal part of the value obtained by dividing the second numerical value by 10 by 10. When the dislocation density in the central square region is a first density, and the average value of the dislocation density in the first outer peripheral rectangular region, the dislocation density in the second outer peripheral rectangular region, the dislocation density in the third outer peripheral rectangular region, and the dislocation density in the fourth outer peripheral rectangular region is a second density, the value obtained by dividing the second density by the first density is less than 203%. When the average value of the dislocation density in the first outer peripheral rectangular region and the dislocation density in the second outer peripheral rectangular region is a third density, and the average value of the dislocation density in the third outer peripheral rectangular region and the dislocation density in the fourth outer peripheral rectangular region is a fourth density, the value obtained by dividing the fourth density by the third density is greater than 84% and less than or equal to 113%. The indium phosphide single crystal substrate according to claim 1.

3. The dislocation density on the main surface is 60 cm －２ or less. The indium phosphide single crystal substrate according to claim 1 or claim 2.

4. The value obtained by dividing the absolute value of the difference between the first concentration and the second concentration by the first concentration is less than 7%. The indium phosphide single crystal substrate according to any one of claims 1 to 3.

5. The indium phosphide single crystal substrate according to any one of claims 1 to 4, wherein the dopant is sulfur.

6. The indium phosphide single crystal substrate according to any one of claims 1 to 4, wherein the dopant is iron.

7. The indium phosphide single crystal substrate according to any one of claims 1 to 4, wherein the dopant is tin.

8. The indium phosphide single crystal substrate according to any one of claims 1 to 7, wherein the main surface is a {100} plane.

9. The main surface includes a central square region that includes the center of the main surface and has a side length of 40 mm, and a first outer peripheral rectangular region, a second outer peripheral rectangular region, a third outer peripheral rectangular region, and a fourth outer peripheral rectangular region that are respectively in the [011] direction, [0-1-1] direction, [01-1] direction, and [0-11] direction with respect to the central square region. The length of the short side of each of the first outer peripheral rectangular region, the second outer peripheral rectangular region, the third outer peripheral rectangular region, and the fourth outer peripheral rectangular region is 20 mm. The length of the long side of each of the first outer peripheral rectangular region, the second outer peripheral rectangular region, the third outer peripheral rectangular region, and the fourth outer peripheral rectangular region is 40 mm. When the distance between the outer peripheral end of each of the first outer peripheral rectangular region, the second outer peripheral rectangular region, the third outer peripheral rectangular region, and the fourth outer peripheral rectangular region and the center of the main surface is a first numerical value, and the radius of the main surface is a second numerical value, and the unit of each of the first numerical value and the second numerical value is mm, the first numerical value is a value obtained by multiplying the integer value obtained by truncating the decimal part of the value obtained by dividing the second numerical value by 10 by 10. When the dislocation density in the central square region is a first density, and the average value of the dislocation density in the first outer peripheral rectangular region, the dislocation density in the second outer peripheral rectangular region, the dislocation density in the third outer peripheral rectangular region, and the dislocation density in the fourth outer peripheral rectangular region is a second density, the value obtained by dividing the second density by the first density is less than 203%. When the average value of the dislocation density in the first outer peripheral rectangular region and the dislocation density in the second outer peripheral rectangular region is a third density, and the average value of the dislocation density in the third outer peripheral rectangular region and the dislocation density in the fourth outer peripheral rectangular region is a fourth density, the value obtained by dividing the fourth density by the third density is greater than 84% and less than or equal to 113%. The dislocation density on the main surface is 60 cm －２ or less. The value obtained by dividing the absolute value of the difference between the first concentration and the second concentration by the first concentration is less than 7%. The indium phosphide single crystal substrate according to claim 1.

10. An indium phosphide single crystal comprising a first end face and a second end face opposite to the first end face, containing a dopant, wherein the diameter of the first end face is 150 mm or more and 160 mm or less, and the length of the indium phosphide single crystal in the direction from the second end face toward the first end face is 50 mm or more and 200 mm or less, and at least one of the dislocation density at the first end face and the dislocation density at the second end face is 90 cm －２ or less. When the concentration of the dopant at the center of the first end face is defined as a third concentration, the concentration of the dopant at the outer edge of the first end face is defined as a fourth concentration, the concentration of the dopant at the center of the second end face is defined as a fifth concentration, and the concentration of the dopant at the outer edge of the second end face is defined as a sixth concentration, at least one of the value obtained by dividing the absolute value of the difference between the third concentration and the fourth concentration by the third concentration and the value obtained by dividing the absolute value of the difference between the fifth concentration and the sixth concentration by the fifth concentration is 11.9% or less. An indium phosphide single crystal.

11. A method for manufacturing an indium phosphide single crystal, comprising: a step of disposing a seed crystal inside a crucible; a step of disposing an indium phosphide raw material on the seed crystal; a step of preparing an indium phosphide melt by melting a part of the seed crystal and the indium phosphide raw material; a step of inserting a stirring member into the indium phosphide melt inside the crucible; and a step of solidifying the indium phosphide melt by moving the crucible while stirring the indium phosphide melt using the stirring member. The stirring member has a main body portion configured to be rotatable, and at least one blade portion attached to the main body portion and extending along a radial direction perpendicular to the rotation axis of the main body portion. In the step of solidifying the indium phosphide melt, the at least one blade portion repeats a reciprocating motion along the rotation direction of the main body portion, and in the reciprocating motion, a state in which the at least one blade portion faces the <011> direction of the seed crystal occurs a plurality of times, and the angular amplitude of the at least one blade portion in the reciprocating motion is 10° or more and 45° or less.

12. The method for manufacturing an indium phosphide single crystal according to claim 11, wherein the at least one fin portion has four fin portions.

13. The method for manufacturing an indium phosphide single crystal according to claim 11 or claim 12, wherein the angular amplitude is 15° or more.

14. The method for manufacturing an indium phosphide single crystal according to any one of claims 11 to 13, wherein the period of the reciprocating motion is 60 seconds or more and 300 seconds or less.

15. The method for manufacturing an indium phosphide single crystal according to any one of claims 11 to 14, wherein the main body portion has a disk member that extends along the radial direction, and the at least one fin portion is attached to the disk member.

16. The method for manufacturing an indium phosphide single crystal according to any one of claims 11 to 15, wherein the thickness of the at least one fin portion in the direction in which the rotation axis of the main body portion extends is 3 mm or more and 10 mm or less.

17. The method for manufacturing an indium phosphide single crystal according to any one of claims 11 to 16, wherein the length of the at least one fin portion in the radial direction is 10 mm or more and 70 mm or less.

18. The method for manufacturing an indium phosphide single crystal according to any one of claims 11 to 17, wherein the shortest distance between the at least one fin portion and the solid-liquid interface of the indium phosphide melt in the direction in which the rotation axis of the main body portion extends is 20 mm or less.

19. The method for manufacturing an indium phosphide single crystal according to any one of claims 11 to 18, wherein the at least one fin portion is composed of quartz or carbon covered with pyrolytic boron nitride.

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