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 150-303 mm. The dislocation density in the main surface is 100 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 less than 10%.

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 303 mm or less. The dislocation density in the primary surface is 100 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 less than 10%.

[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 positions of the dopant concentration of an indium phosphide single crystal substrate. FIG. 4 is a schematic plan view showing the measurement positions 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 positions of the dopant concentration at a first end facet. FIG. 8 is a schematic bottom view showing the measurement positions 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 flow chart showing an outline of a method for producing an indium phosphide single crystal according to this embodiment. FIG. 11 is a partial cross-sectional view showing a step of preparing a growth apparatus. Fig. 12 is a cross-sectional schematic view showing a crucible in which a seed crystal, an indium phosphide raw material, and a sealing material are placed. Fig. 13 is a cross-sectional schematic view showing a step of melting the raw material. Fig. 14 is a cross-sectional schematic view showing a step of inserting an inner cylinder into an indium phosphide melt. Fig. 15 is a cross-sectional schematic view showing a step of growing a crystal. Fig. 16 is a partial cross-sectional schematic view showing the configuration of an indium phosphide single crystal growth apparatus according to a first modified example of this embodiment. Fig. 17 is a partial cross-sectional schematic view showing the configuration of an indium phosphide single crystal growth apparatus according to a second 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 303 mm or less. The dislocation density in the primary surface is 100 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 less than 10%.

[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 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, 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 peripheral rectangular region, the second outer peripheral rectangular region, the third outer peripheral rectangular region, and the fourth outer peripheral rectangular region is a second density, the value obtained by dividing the second density by the first density may be 267% or less. 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 85% and not greater than 120%.

[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 50 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 5%.

[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 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, 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 peripheral rectangular region, the second outer peripheral rectangular region, the third outer peripheral rectangular region, and the fourth outer peripheral rectangular region is a second density, the value obtained by dividing the second density by the first density may be 267% or less. 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 85% and not more than 120%. －２ The absolute value of the difference between the first concentration and the second concentration divided by the first concentration may be less than 5%.

[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 303 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 150 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 100 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, the absolute value of the value obtained by subtracting the fourth concentration from the third concentration and dividing it by the third concentration is less than 10%, 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 less than 10%.

[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 in each of the first facet and the second facet is sufficiently reduced, thereby improving 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; an inner cylinder is inserted into the indium phosphide melt inside the crucible; the indium phosphide melt is solidified by rotating the crucible relative to the inner cylinder by rotating at least one of the inner cylinder and the crucible, while moving the crucible. The crucible has a seed crystal accommodating portion in which a seed crystal is placed, an increasing diameter portion connected to the seed crystal accommodating portion, and a straight body portion provided on the opposite side of the increasing diameter portion from the seed crystal accommodating portion and connected to the increasing diameter portion. The difference between the diameter of the lower end of the inner cylinder and the inner diameter of the straight body portion is 10 mm or more and 110 mm or less.

[0023] This allows the indium phosphide melt to be effectively stirred, reducing fluctuations in dopant concentration and radial temperature differences within the melt. This reduces variations in dopant concentration and dislocation density on the primary surface of an indium phosphide single crystal substrate manufactured using the indium phosphide single crystal, resulting in improved yields of semiconductor devices.

[0024] (12) According to the method for producing an indium phosphide single crystal according to (11) above, the difference between the diameter of the lower end of the inner cylinder and the inner diameter of the straight body portion may be 55 mm or less. This makes it possible to more reliably generate Taylor vortices in the indium phosphide melt. This allows the indium phosphide melt to be stirred more effectively.

[0025] (13) According to the method for producing an indium phosphide single crystal according to (11) or (12), the relative rotation speed of the crucible with respect to the inner cylinder may be 20 rpm or more and less than 200 rpm. This makes it possible to more reliably generate Taylor vortex flows in the indium phosphide melt. This allows the indium phosphide melt to be stirred more effectively.

[0026] (14) In the method for producing an indium phosphide single crystal according to any one of (11) to (13) above, the diameter of the lower end of the inner cylinder may be the same as the diameter of the upper end of the inner cylinder.

[0027] (15) In the method for producing an indium phosphide single crystal according to any one of (11) to (13), the diameter of the lower end of the inner cylinder may be larger than the diameter of the upper end of the inner cylinder, thereby increasing the volume (charge amount) of the indium phosphide melt placed inside the crucible compared to when the diameters of the lower and upper ends of the inner cylinder are the same.

[0028] (16) In the method for producing an indium phosphide single crystal according to any one of (11) to (15) above, the inner cylinder may be solid. This allows the heat capacity of the inner cylinder to be sufficiently increased. This makes it possible to suppress fluctuations in the temperature of the indium phosphide melt when the heat energy applied to the crucible from the heating element fluctuates due to movement of the crucible.

[0029] (17) According to the method for producing an indium phosphide single crystal according to (16) above, the inner cylinder may have a container and a filling member. The filling member may be filled inside the container. The filling member may be made of indium phosphide. This reduces the difference between the thermal conductivity of the indium phosphide melt and the thermal conductivity of the inner cylinder. This suppresses fluctuations in the temperature of the indium phosphide melt when the crucible moves.

[0030] [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.

[0031] <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.

[0032] 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.

[0033] The first main surface 1 is a {100} plane of the single-crystal indium phosphide that constitutes the InP 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.

[0034] 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.

[0035] 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 303 mm. The first diameter W1 may be, for example, equal to or greater than 6 inches (152.4 mm), or may be equal to or greater than 200 mm. The first diameter W1 may be, for example, equal to or less than 300 mm, equal to or less than 10 inches (254 mm), or equal to or less than 250 mm. The first diameter W1 is the longest distance between two different points on the first outer edge 8.

[0036] 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.

[0037] <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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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, 1×10 １６ cm －３ 1x10 or more １９ cm －３ The following is the result.

[0047] 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, 1×10 １６ cm －３ 1x10 or more １９ cm －３ The following is the result.

[0048] 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 by the first concentration (first value) is less than 10%. The first value may be, for example, 0.1% or more, or 1% or more. The first value may be, for example, less than 5%, or 3% or less.

[0049] <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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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 100 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, 60 cm －２ It may be less than 50 cm －２ It may be less than 45 cm －２ It may be the following:

[0059] 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 regarded as the dislocation density at the first center A1 of the first main surface 1. The first density is, for example, 20 cm －２ More than 70cm －２ The following is the result.

[0060] 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, 20 cm －２ 120cm or more －２ The following is the result.

[0061] The value obtained by dividing the second density by the first density (second value A) is 267% or less. The second value A may be, for example, 75% or more, or 90% or more. The second value A may be, for example, 220% or less, 150% or less, or 125% or less.

[0062] 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 85% and equal to or less than 120%. The second value B may be, for example, equal to or greater than 90%, or may be equal to or greater than 95%. The second value B may be, for example, equal to or less than 115%, or may be equal to or less than 110%.

[0063] <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.

[0064] 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.

[0065] 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.

[0066] The length of the InP single crystal 200 in the third direction 103 (second length L2) is 50 mm or more and 150 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, 140 mm or less, or 130 mm or less.

[0067] 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.

[0068] 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 303 mm. The second diameter W2 may be, for example, equal to or greater than 6 inches (152.4 mm), or equal to or greater than 200 mm. The second diameter W2 may be, for example, equal to or less than 300 mm, equal to or less than 10 inches (254 mm), or equal to or less than 250 mm. The second diameter W2 is the longest distance between two different points on the second outer edge 28.

[0069] 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.

[0070] <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).

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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 (third value) is less than 10%. The third value may be, for example, 0.1% or more, or 1% or more. The third value may be, for example, 5% or less, or 3% or less.

[0086] 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, 1×10 １６ cm －３ 5x10 or more １８ cm －３ The following is the result.

[0087] The average 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, 1×10 １６ cm －３ 5x10 or more １８ cm －３ The following is the result.

[0088] 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 (fourth value) is less than 10%. The fourth value may be, for example, 0.1% or more, or 1% or more. The fourth value may be, for example, 5% or less, or 3% or less.

[0089] 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.

[0090] <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.

[0091] 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.

[0092] 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.

[0093] At least one of the dislocation density at the first end face 21 and the dislocation density at the second end face 22 is 100 cm －２ The dislocation density at the first end face 21 is, for example, 1 cm －２ It may be more than 10 cm －２The dislocation density at the first end face 21 may be, for example, 80 cm －２ It may be less than 65 cm －２ It may be less than 55 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, 85 cm －２ It may be less than 55 cm －２ It may be less than 45 cm －２ It may be the following:

[0094] <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, an inner cylinder 50, a crucible support 60, a first shaft 55, a second shaft 56, and a heating element 48.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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 350 mm or less.

[0100] 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.

[0101] 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.

[0102] The inner cylinder 50 is disposed inside the crucible 40. The inner cylinder 50 is surrounded by the straight body portion 43. The inner cylinder 50 has, for example, a cylindrical shape. The inner cylinder 50 is solid. The inner cylinder 50 is made of, for example, quartz or carbon covered with pBN. The inner cylinder 50 has a lower end 51, an upper end 52, and a side surface 53.

[0103] The lower end 51 faces the bottom portion 41a. When viewed in the third direction 103, the shape of the lower end 51 is circular. The diameter of the lower end 51 (third diameter W3) is, for example, 40 mm or more and 280 mm or less. The third diameter W3 is smaller than the inner diameter D of the straight body portion 43. The difference between the third diameter W3 and the inner diameter D is 10 mm or more and 110 mm or less. The difference between the third diameter W3 and the inner diameter D may be, for example, 20 mm or more, or 30 mm or more. The difference between the third diameter W3 and the inner diameter D may be, for example, 80 mm or less, 55 mm or less, or 35 mm or less.

[0104] The upper end 52 is provided in the third direction 103 relative to the lower end 51. When viewed along the fourth direction 104, the shape of the upper end 52 is circular. The diameter of the upper end 52 (fourth diameter W4) may be the same as the third diameter W3, for example. The side surface 53 is continuous with each of the lower end 51 and the upper end 52. The side surface 53 extends along the third direction 103. When viewed along the third direction 103, the shape of the side surface 53 is, for example, circular. The diameter of the side surface 53 may be substantially the same as the third diameter W3.

[0105] The second shaft 56 is attached to the inner cylinder 50 at the upper end 52. The second shaft 56 is disposed in a third direction 103 relative to the inner cylinder 50. 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 inner cylinder 50 is configured to be rotatable around the central axis X. From yet another perspective, the inner cylinder 50 and the crucible 40 are configured to be rotatable relative to each other. The second shaft 56 is configured to be movable along a direction parallel to the third direction 103. From another perspective, the inner cylinder 50 is configured to be movable along a direction parallel to the third direction 103.

[0106] <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.

[0107] Fig. 10 is a flow chart schematically showing a method for manufacturing an InP single crystal 200 according to this embodiment. As shown in Fig. 10, the method for manufacturing 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 an inner cylinder into the indium phosphide melt, a step (S60) of growing the crystal, and a step (S70) of cutting the crystal.

[0108] First, a step (S10) of preparing a growth apparatus is performed. Fig. 11 is a partial cross-sectional schematic diagram showing the step (S10) of preparing a growth apparatus 300. As shown in Fig. 11, the growth apparatus 300 according to this embodiment is prepared. In the step (S10) of preparing a growth apparatus, the inner cylinder 50 is disposed outside the crucible 40. For ease of explanation, the inner cylinder 50 and the second shaft 56 are not shown in Fig. 11.

[0109] Next, the step of placing a seed crystal (S20) is performed. Fig. 12 is a schematic cross-sectional view showing crucible 40 in which seed crystal 84, indium phosphide source material 85, and sealing material 86 are placed. As shown in Fig. 12, in the step of placing a seed crystal (S20), seed crystal 84 is placed inside seed crystal accommodation portion 41. Seed crystal 84 is made of single-crystal indium phosphide. Seed crystal 84 may contain any one of sulfur, iron, and tin as an impurity atom.

[0110] Next, a step (S30) of arranging indium phosphide source materials and a sealing material is performed. As shown in FIG. 12 , 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, 10 kg. One of sulfur, iron, and tin is arranged inside the crucible 40 as an impurity.

[0111] 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.

[0112] 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.

[0113] 13 is a cross-sectional view schematically illustrating the step (S40) of melting the raw material. As shown in FIG. 13, 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.

[0114] Next, the step (S50) of inserting the inner cylinder into the indium phosphide melt is performed. FIG. 14 is a cross-sectional schematic diagram illustrating the step (S50) of inserting the inner cylinder into the indium phosphide melt. As shown in FIG. 14 , the inner cylinder 50 is moved along the fourth direction 104 using the second axis 56, thereby inserting the inner cylinder 50 into the InP melt 87 inside the crucible 40. The lower end 51 is located in the fourth direction 104 relative to the straight body portion 43. The lower end 51 is surrounded by the increasing diameter portion 42. The upper end 52 is located in the third direction 103 relative to the straight body portion 43. The inner cylinder 50 is located in the third direction 103 relative to the seed crystal 84. The InP melt 87 is located between the inner cylinder 50 and the straight body portion 43. The InP melt 87 is located between the inner cylinder 50 and the increasing diameter portion 42.

[0115] Next, the step of growing a crystal (S60) is performed. FIG. 15 is a cross-sectional schematic diagram illustrating the step of growing a crystal (S60). As shown in FIG. 15 , the crucible 40 rotates around the central axis X, for example, along the arrow C. The inner cylinder 50 is, for example, stationary. This causes the crucible 40 to rotate relative to the inner cylinder 50. The relative rotation speed of the crucible 40 with respect to the inner cylinder 50 is, for example, 20 rpm or more and less than 200 rpm. The relative rotation speed of the crucible 40 with respect to the inner cylinder 50 may be, for example, 40 rpm or more, or 80 rpm or more. The relative rotation speed of the crucible 40 with respect to the inner cylinder 50 may be, for example, 160 rpm or less, or 120 rpm or less. This causes a flow to occur in the InP melt 87. Therefore, the InP melt 87 is stirred.

[0116] The crucible 40 is rotated relative to the inner cylinder 50, and is moved along the fourth direction 104. This reduces the temperature of the portion of the InP melt 87 close to the remainder of the seed crystal 84. The moving speed of the crucible 40 in the fourth direction 104 is set to, for example, 2 mm / hour or more and 5 mm / hour or less. The InP melt 87 in contact with the remainder of the seed crystal 84 solidifies, thereby growing an indium phosphide crystal 210 (hereinafter also referred to as an InP crystal 210).

[0117] 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, 1%. 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. Stirring by the inner cylinder 50 has the effect of reducing the radial temperature difference within the InP melt 87, and can reduce the degree of convexity of the solid-liquid interface I. By reducing the degree of convexity to less than 3% by stirring the melt by the inner cylinder 50, the dislocation density in the InP single crystal 200 can be reduced. The radial direction is perpendicular to the central axis X and is the direction from the central axis X toward the crucible 40. The shortest distance E between the solid-liquid interface I and the lower end 51 in the third direction 103 is, for example, not less than 5 mm and not more than 20 mm.

[0118] 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.

[0119] 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).

[0120] 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.

[0121] 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.

[0122] 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 in 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 make it easier for twins to form, resulting in a decrease in the single crystal yield. In this case, if the InP single crystal 200 is grown under conditions with a large temperature gradient to suppress twins caused by temperature fluctuations, the dislocation density in the InP single crystal 200 increases.

[0123] Based on the above findings, the inventors came up with the idea of ​​stirring the InP melt 87. Specifically, they came up with the idea of ​​inserting the inner cylinder 50 into the InP melt 87 and then rotating the inner cylinder 50 and the crucible 40 relative to each other. By rotating the inner cylinder 50 and the crucible 40 relative to each other, a flow such as a Taylor vortex is generated in the InP melt 87. Taylor vortexes are resistant to external disturbances. Therefore, even if temperature fluctuations occur in the InP melt 87, the InP melt 87 can be stably stirred. By using this flow to stir the InP melt 87, temperature variations and radial temperature differences in the InP melt 87 can be reduced. This reduces variations in dopant concentration in the InP single crystal 200, and eliminates the need to make the solid-liquid interface I excessively convex as a twinning countermeasure, thereby reducing the dislocation density in the InP single crystal 200.

[0124] According to the method for producing the InP single crystal 200 of this embodiment, the crucible 40 is rotated relative to the inner cylinder 50 while the crucible 40 is moved, thereby solidifying the InP melt 87. Therefore, the relative rotation between the inner cylinder 50 and the crucible 40 causes a flow in the InP melt 87. This allows the InP melt 87 to be effectively stirred. This reduces the temperature variation and radial temperature difference of the InP melt 87. Therefore, the dopant concentration variation and dislocation density in the InP single crystal 200 can be reduced. This reduces the dopant concentration variation and dislocation density on the primary surface of the InP single crystal substrate 100 produced using the InP single crystal 200. As a result, the yield of semiconductor devices can be improved.

[0125] If the difference between the diameter of the lower end of the inner cylinder 50 and the inner diameter of the straight body portion 43 of the crucible 40 is excessively large, the InP melt 87 will not be sufficiently stirred by the flow caused by the relative rotation between the inner cylinder 50 and the crucible 40. According to the method for producing the InP single crystal 200 of this embodiment, the difference between the diameter of the lower end of the inner cylinder 50 and the inner diameter of the straight body portion 43 of the crucible 40 is 110 mm or less. This allows the InP melt 87 to be sufficiently stirred. As a result, the variation in dopant concentration and the dislocation density in the InP single crystal 200 can be reduced.

[0126] If the difference between the diameter of the lower end of the inner cylinder 50 and the inner diameter of the straight body portion 43 of the crucible 40 is excessively small, the volume (charge amount) of the InP source material 85 that can be filled inside the crucible 40 becomes excessively small. In this case, the productivity of the InP single crystal 200 decreases. According to the method for producing the InP single crystal 200 according to this embodiment, the difference between the diameter of the lower end of the inner cylinder 50 and the inner diameter of the straight body portion 43 of the crucible 40 is 10 mm or more. Therefore, a decrease in the productivity of the InP single crystal 200 can be suppressed.

[0127] By reducing the degree of convexity in the InP melt 87, the temperature distribution in the InP melt 87 may be reduced. In this case, twins are likely to occur at the outer peripheral facet portion of the InP single crystal 200 due to constitutional supercooling that occurs with solidification segregation of the InP melt 87. According to the InP single crystal 200 of this embodiment, the InP melt 87 can be sufficiently stirred, so that constitutional supercooling of the InP melt 87 can be suppressed and temperature fluctuations within the melt can also be reduced. As a result, the occurrence of twins in the InP single crystal 200 can be suppressed.

[0128] By appropriately setting the difference between the diameter of the lower end of the inner cylinder 50 and the inner diameter of the straight body portion 43 of the crucible 40, Taylor vortices can be more reliably generated in the InP melt 87. This allows the InP melt 87 to be stirred more effectively. According to the method for producing the InP single crystal 200 of this embodiment, the difference between the diameter of the lower end of the inner cylinder 50 and the inner diameter of the straight body portion 43 of the crucible 40 is 55 mm or less. This allows Taylor vortices to be more reliably generated in the InP melt 87. This allows the InP melt 87 to be stirred more effectively.

[0129] By appropriately setting the relative rotation speed of the crucible 40 with respect to the inner cylinder 50, Taylor vortices can be more reliably generated in the InP melt 87. On the other hand, if the relative rotation speed of the crucible 40 with respect to the inner cylinder 50 is excessively fast, turbulence occurs in the InP melt 87, making it easier for twins to form. According to the method for producing the InP single crystal 200 of this embodiment, the relative rotation speed of the crucible 40 with respect to the inner cylinder 50 is equal to or greater than 20 rpm and less than 200 rpm. This makes it possible to more reliably generate Taylor vortices in the InP melt 87. This allows the InP melt 87 to be stirred more effectively.

[0130] According to the method for producing the InP single crystal 200 of this embodiment, the inner cylinder 50 is solid. This allows the heat capacity of the inner cylinder 50 to be sufficiently increased. As a result, compared to when the inner cylinder 50 is hollow, fluctuations in the temperature of the InP melt 87 can be suppressed when the heat energy applied to the crucible 40 from the heating element 48 fluctuates due to movement of the crucible 40.

[0131] According to the InP single crystal substrate 100 of this embodiment, the dislocation density on the first main surface 1 is 100 cm －２ or less. The absolute value of the value obtained by subtracting the second concentration from the first concentration and dividing the result by the first concentration is less than 10%. 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.

[0132] In the InP single crystal substrate 100 according to this embodiment, the value obtained by dividing the second density by the first density is 267% or less. In this way, 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.

[0133] 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.

[0134] 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.

[0135] 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 100 cm －２ or less. The absolute value of the value obtained by subtracting the fourth concentration from the third concentration and dividing it by the third concentration is less than 10%. The absolute value of the value obtained by subtracting the sixth concentration from the fifth concentration and dividing it by the fifth concentration is less than 10%. In this way, the dislocation density is sufficiently reduced, and the variation in the dopant concentration at each 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.

[0136] (Modifications) Next, a modification of the method for producing an InP single crystal 200 according to this embodiment will be described. FIG. 16 is a partial cross-sectional schematic diagram showing the configuration of a growth apparatus 300 for an InP single crystal 200 according to a first modification of this embodiment. As shown in FIG. 16 , the shape of the inner cylinder 50 may be a truncated cone. From another perspective, the diameter of the side surface 53 may decrease with increasing distance from the lower end 51 along the third direction 103. From yet another perspective, the diameter of the lower end 51 (third diameter W3) may be larger than the diameter of the upper end 52 (fourth diameter W4). In other words, the fourth diameter W4 may be smaller than the third diameter W3. By making the fourth diameter W4 larger than the third diameter W3, the volume (charge amount) of the InP melt 87 placed inside the crucible 40 can be increased compared to when the third diameter W3 and the fourth diameter W4 are the same. This allows the length (second length L2) of the InP single crystal 200 to be longer.

[0137] FIG. 17 is a partial cross-sectional schematic diagram showing the configuration of a growth apparatus 300 for an InP single crystal 200 according to a second modification of this embodiment. As shown in FIG. 17 , the inner cylinder 50 may have a container 57 and a filler 58. The container 57 is cylindrical and has a bottom. The container 57 comprises a lower end 51, an upper end 52, and a side surface 53. The container 57 is made of quartz or carbon coated with pBN. The filler 58 fills the interior of the container 57. From another perspective, the contents of the inner cylinder 50 are made of the filler 58. The filler 58 is made of, for example, polycrystalline indium phosphide. In the step (S10) of preparing a growth apparatus, the filler 58 is, for example, cylindrical. In the step (S50) of inserting the inner cylinder into the indium phosphide melt, the filler 58 may be melted. In the step ( S60 ) of growing a crystal, filling member 58 is separated from InP melt 87 by container 57 .

[0138] The filler member 58 is made of indium phosphide, which reduces the difference between the thermal conductivity of the InP melt 87 and the thermal conductivity of the inner cylinder 50. This reduces fluctuations in the temperature of the InP melt 87 when the crucible 40 moves. A space may be provided between the filler member 58 and the container 57.

[0139] In the crystal growing step (S60) of the manufacturing method of the InP single crystal 200 according to this embodiment, the inner cylinder 50 may rotate around the central axis X. Specifically, both the inner cylinder 50 and the crucible 40 may rotate, or only one of the inner cylinder 50 and the crucible 40 may rotate. In the crystal growing step (S60), the crucible 40 may rotate relative to the inner cylinder 50 by rotating at least one of the inner cylinder 50 and the crucible 40. When both the inner cylinder 50 and the crucible 40 are rotating, the rotation direction of the inner cylinder 50 and the rotation direction of the crucible 40 may be the same or different.

[0140] <Sample Preparation> First, InP single crystals 200 according to Samples 1 to 13 were prepared. The InP single crystals 200 according to Samples 1 to 4 were used as comparative examples. The InP single crystals 200 according to Samples 5 to 13 were used as working examples. The InP single crystals 200 according to Samples 1 to 13 were manufactured according to the above-described method for manufacturing the InP single crystal 200. Specifically, the InP single crystals 200 were manufactured using the conditions shown in Table 1 below.

[0141]

[0142] Table 1 shows the manufacturing conditions for the InP single crystal 200 for Samples 1 to 13. As shown in Table 1, the diameter of the first end facet 21 (second diameter W2) was 152 mm for Samples 1 to 10, 12, and 13. For Sample 11, the second diameter W2 was 303 mm. For Samples 1 to 11, the dopant was sulfur. For Sample 12, the dopant was iron. For Sample 13, the dopant was tin.

[0143] In Samples 1 and 2, the convexity of the solid-liquid interface I was set to 10%. In Samples 3 and 4, the convexity of the solid-liquid interface I was set to 3%. In Samples 5 to 13, the convexity of the solid-liquid interface I was set to 1%.

[0144] In Samples 1 to 4, the inner cylinder 50 was not used. In Samples 5 to 13, the inner cylinder 50 was used. In Samples 5 to 13, the shape of the inner cylinder 50 was cylindrical. In Samples 5 to 13, the diameter of the lower end of the inner cylinder 50 (third diameter W3) was 50 mm or more and 260 mm or less. In Samples 5 to 13, the difference between the inner diameter D of the crucible and the diameter of the lower end of the inner cylinder 50 (third diameter W3) was 31 mm or more and 106 mm or less.

[0145] In Samples 1 and 3, the rotation speed of the crucible 40 was 2 rpm. In Samples 2 and 4, the rotation speed of the crucible 40 was 200 rpm. In Samples 5 to 13, the crucible 40 was rotated relative to the inner cylinder 50 by rotating the crucible 40 and keeping the inner cylinder 50 stationary. In Samples 5 to 13, the rotation speed of the crucible 40 was 10 rpm or more and 150 rpm or less. From another perspective, in Samples 5 to 13, the relative rotation speed between the inner cylinder 50 and the crucible 40 was 10 rpm or more and 150 rpm or less.

[0146] In Samples 1 to 10, 12, and 13, the inner diameter D of crucible 40 was 156 mm. In Sample 11, the inner diameter D of crucible 40 was 307 mm. The weight of InP source material 85 was 10 kg. The weight of sealing material 86 was 2850 g. In the crystal growing step (S60), the moving speed of crucible 40 in fourth direction 104 was 2.5 mm / hour.

[0147] <Experimental Method> The presence or absence of twins was confirmed for the InP single crystals 200 of Samples 1 to 13. 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.

[0148] For Samples 1 to 13, 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.

[0149] 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.

[0150] The fourth density described above was measured at each of the first end face 21 and the second end face 22. Specifically, the dislocation density was measured in regions corresponding to the third peripheral rectangular region 13 and the fourth peripheral rectangular region 14 described above at each of the first end face 21 and the second end face 22. The first density, the third density, and the fourth density were used to calculate the second value A and the second value B described above at each of the first end face 21 and the second end face 22.

[0151]

[0152] 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 13. As shown in Table 2, among the samples according to the embodiment, twins occurred in Samples 5 and 9. No twins occurred in Samples 6 to 8 and 10 to 13.

[0153] In Samples 1 to 4, the fourth value was 10% or more. The third value was 10% or more. In Samples 5 to 13, the fourth value was 9.5% or less. The third value was 9.5% or less.

[0154]

[0155] Table 3 shows the results of measuring the dislocation density in the InP single crystal 200 for Samples 1 to 13. In Table 3, "ND" indicates that the dislocation density could not be measured due to the occurrence of twins in the InP single crystal 200.

[0156] As shown in Table 3, in Samples 1 and 2, the dislocation density at the second end face 22 was 300 cm －２ In samples 3 to 13, the dislocation density at the second end face 22 was 80 cm －２ It was as follows.

[0157] In samples 1 and 2, the dislocation density at the first end face 21 was 100 cm －２ In samples 6 to 8 and 10 to 13, the dislocation density at the first end face 21 was 60 cm －２ In Samples 3 to 5 and 9, the dislocation density at the first end face 21 could not be measured.

[0158] In Samples 5 to 13, the second value A at the second end surface 22 was 167% or more and 267% or less. In Samples 6 to 8 and 10 to 13, the second value A at the first end surface 21 was 100% or more and 267% or less.

[0159] In Samples 5 to 13, the second value B at the second end surface 22 was 100% or more and 133% or less. In Samples 6 to 13, the second value B at the second end surface 22 was 100% or more and 114% or less. In Samples 6 to 8 and 10 to 13, the second value B at the first end surface 21 was 86% or more and 120% or less.

[0160] From the above, it was confirmed that the method for manufacturing the InP single crystal 200 according to the embodiment can reduce the variation in dopant concentration and the dislocation density at the second end facet 22 compared to the method for manufacturing the InP single crystal 200 according to the comparative example.

[0161] Furthermore, when the difference between the inner diameter D and the third diameter W3 is 31 mm or more and 81 mm or less and the rotation speed of the crucible 40 is 100 rpm or more and 150 rpm or less (samples 6 to 8 and 10 to 13), it was confirmed that the occurrence of twins can be suppressed while the variation in dopant concentration, the dislocation density at the first end face 21, and the dislocation density at the second end face 22 can be reduced.

[0162] 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 the above description, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0163] 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 Inner cylinder, 51 Lower end, 52 Upper end, 53 Side surface, 55 First axis, 56 Second axis, 57 Storage portion, 58 Filler member, 60 Crucible support 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, 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, D inner diameter, E shortest distance, H height, I solid-liquid interface, L1 first length, L2 second length, O center, R1 first radius, R2 second radius, W1 first diameter, W2 second diameter, W3 third diameter, W4 fourth diameter, X central axis.

Claims

1. It has a main surface, contains a dopant, the diameter of the main surface is 150 mm or more and 303 mm or less, the dislocation density on the main surface is 100 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 less than 10%. An indium phosphide single crystal substrate.

2. 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 267% or less. 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 85% and less than or equal to 120%. The indium phosphide single crystal substrate according to claim 1.

3. The dislocation density on the main surface is 50 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 5%. 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 the first numerical value, and the radius of the main surface is the 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 the 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 the second density, the value obtained by dividing the second density by the first density is 267% or less. 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 the 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 the fourth density, the value obtained by dividing the fourth density by the third density is greater than 85% and 120% or less. The dislocation density on the main surface is 50 cm －２ or less, and 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 5%. The indium phosphide single crystal substrate according to claim 1.

10. An indium phosphide single crystal having 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 303 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 150 mm or less, and at least one of the dislocation density on the first end face and the dislocation density on the second end face is 100 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, the value obtained by dividing the absolute value of the difference between the third concentration and the fourth concentration by the third concentration is less than 10%, 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 less than 10%. 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 an inner cylinder into the indium phosphide melt inside the crucible; and a step of solidifying the indium phosphide melt by relatively rotating the crucible with respect to the inner cylinder by rotating at least one of the inner cylinder and the crucible and moving the crucible. The crucible includes: a seed crystal accommodating portion where the seed crystal is disposed; a diameter increasing portion continuous with the seed crystal accommodating portion; and a straight barrel portion provided opposite to the seed crystal accommodating portion with respect to the diameter increasing portion and continuous with the diameter increasing portion. The difference between the diameter of the lower end of the inner cylinder and the inner diameter of the straight barrel portion is 10 mm or more and 110 mm or less.

12. The method for manufacturing an indium phosphide single crystal according to claim 11, wherein the difference between the diameter of the lower end of the inner cylinder and the inner diameter of the straight barrel portion is 55 mm or less.

13. The relative rotational speed of the crucible with respect to the inner cylinder is 20 rpm or more and less than 200 rpm. The method for manufacturing an indium phosphide single crystal according to claim 11 or claim 12.

14. The diameter of the lower end of the inner cylinder is the same as the diameter of the upper end of the inner cylinder. The method for manufacturing an indium phosphide single crystal according to any one of claims 11 to 13.

15. The diameter of the lower end of the inner cylinder is larger than the diameter of the upper end of the inner cylinder. The method for manufacturing an indium phosphide single crystal according to any one of claims 11 to 13.

16. The inner cylinder is solid. The method for manufacturing an indium phosphide single crystal according to any one of claims 11 to 15.

17. The inner cylinder includes a housing portion and a filling member filled inside the housing portion. The filling member is made of indium phosphide. The method for manufacturing an indium phosphide single crystal according to claim 16.

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