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

Abstract

The indium phosphide single-crystal substrate has a main surface. The indium phosphide single-crystal substrate contains dopants. The diameter of the main surface is greater than 150 mm and less than 303 mm. The dislocation density of the main surface is 100 cm⁻¹. ‑2 Below, when the concentration of the dopant at the center of the main surface is set as the first concentration and the concentration of the dopant at the outer edge of the main surface is set as the second concentration, the absolute value of the value obtained by subtracting the second concentration from the first concentration and dividing it by the first concentration is less than 10%.

Description

Technical Field

[0001] This invention relates to indium phosphide single crystal substrates, indium phosphide single crystals, and methods for manufacturing indium phosphide single crystals. Background Technology

[0002] Japanese Patent Application Publication No. 2019-043788 (Patent Document 1) discloses an average dislocation density of 2500 dislocations / cm. 2 Indium phosphide single crystals.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent document 1: Japanese Patent Application Publication No. 2019-043788. Summary of the Invention

[0006] The indium phosphide single-crystal substrate of the present invention has a main surface. The indium phosphide single-crystal substrate contains a dopant. The diameter of the main surface is 150 mm or more and 303 mm or less. The dislocation density of the main surface is 100 cm⁻¹. -2 Below, when the concentration of the dopant at the center of the main surface is set as the first concentration and the concentration of the dopant at the outer edge of the main surface is set as the second concentration, the absolute value of the value obtained by subtracting the second concentration from the first concentration and dividing it by the first concentration is less than 10%. Attached Figure Description

[0007] Figure 1 This is a schematic top view showing the structure of the indium phosphide single crystal substrate of this embodiment.

[0008] Figure 2 This is a schematic side view showing the structure of the indium phosphide single crystal substrate of this embodiment.

[0009] Figure 3 This is a schematic top view showing the location where the dopant concentration of an indium phosphide single crystal substrate was measured.

[0010] Figure 4 This is a schematic top view showing the location where the dislocation density of an indium phosphide single crystal substrate was measured.

[0011] Figure 5 This is a schematic top view showing the structure of the indium phosphide single crystal of this embodiment.

[0012] Figure 6 This is a schematic side view showing the structure of the indium phosphide single crystal of this embodiment.

[0013] Figure 7 This is a schematic top view showing the location where the dopant concentration is measured on the first end face.

[0014] Figure 8 This is a schematic bottom view showing the location where the dopant concentration is measured on the second end face.

[0015] Figure 9 This is a schematic cross-sectional view showing the structure of the indium phosphide single crystal growth apparatus of this embodiment.

[0016] Figure 10 This is a flowchart that schematically illustrates the method for manufacturing indium phosphide single crystals according to this embodiment.

[0017] Figure 11 This is a schematic partial cross-sectional view showing the process of preparing the growth apparatus.

[0018] Figure 12 This is a schematic cross-sectional view showing a crucible containing a seed crystal, indium phosphide raw material, and sealing material.

[0019] Figure 13 This is a schematic cross-sectional view showing the process of molten raw materials.

[0020] Figure 14 This is a schematic cross-sectional view showing the process of inserting an inner cylinder into molten indium phosphide.

[0021] Figure 15 This is a schematic cross-sectional view showing the process of crystal growth.

[0022] Figure 16 This is a schematic partial cross-sectional view showing the structure of the indium phosphide single crystal growth apparatus of the first modified example of this embodiment.

[0023] Figure 17 This is a schematic partial cross-sectional view showing the structure of the indium phosphide single crystal growth apparatus of the second variation of this embodiment. Detailed Implementation

[0024] [The problem this invention aims to solve]

[0025] The purpose of this invention 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 devices.

[0026] [Effects of the Invention]

[0027] According to the present invention, an indium phosphide single crystal substrate, an indium phosphide single crystal, and a method for manufacturing an indium phosphide single crystal can be provided, which can improve the yield of semiconductor devices.

[0028] [Summary of Implementation Methods]

[0029] First, a summary of the embodiments of the present invention (also referred to as this embodiment) will be described. In the crystallographic description of this specification, [] represents a single crystal direction, <> represents a family of crystal directions, () represents a single crystal plane, and {} represents a family of crystal planes. Furthermore, regarding negative exponents, in crystallography, they are indicated by marking "- (hyphen)" above the number, while in this specification, a minus sign is appended before the number.

[0030] (1) The indium phosphide single crystal substrate of the present invention has a main surface. The indium phosphide single crystal substrate contains a dopant. The diameter of the main surface is 150 mm or more and 303 mm or less. The dislocation density of the main surface is 100 cm⁻¹. -2 Below, when the concentration of the dopant at the center of the main surface is set as the first concentration and the concentration of the dopant at the outer edge of the main surface is set as the second concentration, the absolute value of the value obtained by subtracting the second concentration from the first concentration and dividing it by the first concentration is less than 10%.

[0031] In this way, the dislocation density on the main surface is sufficiently reduced, and the deviation in dopant concentration on the main surface is sufficiently reduced. Therefore, the yield of semiconductor devices manufactured using indium phosphide single-crystal substrates can be improved.

[0032] (2) Based on the indium phosphide single crystal substrate described in (1) above, the main surface may include a central square region and a first outer rectangular region, a second outer rectangular region, a third outer rectangular region, and a fourth outer rectangular region. The central square region includes the center of the main surface and has a side length of 40 mm. The first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region are located relative to the central square region in the

[011] direction, the [0-1-1] direction, the [01-1] direction, and the [0-11] direction, respectively. The length of the short side of each 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 the long side of each 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 perimeter of each of the first, second, third, and fourth outer rectangular regions and the center of the main surface is set as a first value, and the radius of the main surface is set as a second value, and the units of the first and second values ​​are each mm, the first value can be the integer value obtained by dividing the second value by 10 and discarding the decimal point, then multiplying by 10. When the dislocation density of the central square region is set as the first density, and the average of the dislocation densities of the first, second, third, and fourth outer rectangular regions is set as the second density, the value obtained by dividing the second density by the first density can be 267% or less. When the average of the dislocation densities of the first and second outer rectangular regions is set as the third density, and the average of the dislocation densities of the third and fourth outer rectangular regions is set as the fourth density, the value obtained by dividing the fourth density by the third density can be greater than 85% and less than 120%.

[0033] In this way, the deviation in dislocation density on the main surface can be sufficiently reduced. Therefore, the yield of semiconductor devices manufactured using indium phosphide single-crystal substrates can be improved.

[0034] (3) Based on the indium phosphide single crystal substrate described in (1) or (2) above, the dislocation density on the main surface can be 50 cm⁻¹. -2 the following.

[0035] (4) For any one of (1) to (3) above, the absolute value of the value of the first concentration minus the second concentration divided by the first concentration is less than 5%.

[0036] (5) For any one of (1) to (4) above, the indium phosphide single crystal substrate may be sulfur.

[0037] (6) For any one of (1) to (4) above, the indium phosphide single crystal substrate may be iron as the dopant.

[0038] (7) The dopant of the indium phosphide single crystal substrate according to any one of (1) to (4) above can be tin.

[0039] (8) For any one of (1) to (7) above, the main surface of the indium phosphide single crystal substrate can be a {100} plane. In this way, even if the growth direction is... <100> The direction of twin formation is also suppressed.

[0040] (9) Based on the indium phosphide single crystal substrate described in (1) above, the main surface may include a central square region and a first outer rectangular region, a second outer rectangular region, a third outer rectangular region, and a fourth outer rectangular region. The central square region includes the center of the main surface and has a side length of 40 mm. The first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region are located relative to the central square region in the

[011] direction, the [0-1-1] direction, the [01-1] direction, and the [0-11] direction, respectively. The length of the short side of each 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 the long side of each 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 perimeter of each of the first, second, third, and fourth outer rectangular regions and the center of the main surface is set as a first value, and the radius of the main surface is set as a second value, and the units of the first and second values ​​are each mm, the first value can be the integer value obtained by dividing the second value by 10 and discarding the decimal point, then multiplying by 10. When the dislocation density of the central square region is set as the first density, and the average of the dislocation densities of the first, second, third, and fourth outer rectangular regions is set as the second density, the value obtained by dividing the second density by the first density can be 267% or less. When the average of the dislocation densities of the first and second outer rectangular regions is set as the third density, and the average of the dislocation densities of the third and fourth outer rectangular regions is set as the fourth density, the value obtained by dividing the fourth density by the third density can be greater than 85% and less than 120%. The dislocation density on the main surface can be 50 cm⁻¹ -2 The absolute value of the difference between the first and second concentrations, divided by the first concentration, is less than 5%.

[0041] (10) The indium phosphide single crystal of the present invention is an indium phosphide single crystal having a first end face and a second end face opposite to 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 of the first end face and the dislocation density of the second end face is 100 cm⁻¹. -2 Below, when the concentration of the dopant at the center of the first end face is set to the third concentration, the concentration of the dopant at the outer edge of the first end face is set to the fourth concentration, the concentration of the dopant at the center of the second end face is set to the fifth concentration, and the concentration of the dopant at the outer edge of the second end face is set to the 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%.

[0042] In this way, the dislocation density is sufficiently reduced in at least one of the first and second end faces, and the deviation in dopant concentration between the first and second end faces is sufficiently reduced. Therefore, the yield of semiconductor devices manufactured using indium phosphide single crystals can be improved.

[0043] (11) The method for manufacturing indium phosphide single crystals of the present invention includes the following steps: A seed crystal is disposed inside a crucible. Indium phosphide raw material is disposed on the seed crystal. Indium phosphide molten liquid is prepared by melting a portion of the seed crystal and the indium phosphide raw material. An inner cylinder is inserted into the indium phosphide molten liquid inside the crucible. The indium phosphide molten liquid is solidified by rotating at least one of the inner cylinder and the crucible relative to the inner cylinder and moving the crucible. The crucible includes: a seed crystal receiving portion on which the seed crystal is disposed; an expanded diameter portion connected to the seed crystal receiving portion; and a straight cylindrical portion disposed on the side opposite to the expanded diameter portion and connected to the expanded diameter portion. The difference between the diameter of the lower end of the inner cylinder and the inner diameter of the straight cylindrical portion is 10 mm or more and 110 mm or less.

[0044] This allows for effective stirring of the indium phosphide molten liquid, reducing fluctuations in dopant concentration and radial temperature differences within the molten liquid. Consequently, dopant concentration variations and dislocation densities can be reduced on the main surface of indium phosphide single-crystal substrates manufactured using indium phosphide single crystals. As a result, the yield of semiconductor devices can be improved.

[0045] (12) According to the manufacturing method of indium phosphide single crystal described in (11) above, the difference between the diameter of the lower end of the inner cylinder and the inner diameter of the straight cylinder can be less than 55 mm. Therefore, Taylor eddies can be generated more reliably in the indium phosphide molten liquid. As a result, the indium phosphide molten liquid can be stirred more effectively.

[0046] (13) According to the manufacturing method of indium phosphide single crystal described in (11) or (12) above, the relative rotation speed of the crucible relative to the inner cylinder can be 20 rpm or more and less than 200 rpm. Therefore, Taylor eddies can be generated more reliably in the indium phosphide molten liquid. As a result, the indium phosphide molten liquid can be stirred more effectively.

[0047] (14) According to any one of the above (11) to (13) manufacturing methods of indium phosphide single crystal, the diameter of the lower end of the inner cylinder can be the same as the diameter of the upper end of the inner cylinder.

[0048] (15) According to any one of the above (11) to (13) manufacturing methods for indium phosphide single crystals, the diameter of the lower end of the inner cylinder can be larger than the diameter of the upper end of the inner cylinder. Thus, compared with the case where the diameter of the lower end of the inner cylinder and the diameter of the upper end of the inner cylinder are the same, the volume (filling amount) of the indium phosphide molten liquid disposed inside the crucible can be increased.

[0049] (16) According to any one of the manufacturing methods of indium phosphide single crystals in (11) to (15) above, the inner cylinder can be solid. Therefore, the heat capacity of the inner cylinder can be sufficiently increased. As a result, when the heat energy applied to the crucible from the heating element changes due to the movement of the crucible, the temperature change of the indium phosphide melt can be suppressed.

[0050] (17) According to the manufacturing method of indium phosphide single crystal described in (16) above, the inner cylinder may have a receiving portion and a filling member. The filling member may be filled inside the receiving portion. The filling member may be made of indium phosphide. As a result, the difference between the thermal conductivity of the indium phosphide molten liquid and the thermal conductivity of the inner cylinder can be reduced. Therefore, the temperature fluctuation of the indium phosphide molten liquid during crucible movement is suppressed.

[0051] [Detailed Description of Implementation Methods]

[0052] Hereinafter, embodiments of the present invention will be described in detail based on the accompanying drawings. Furthermore, in the following drawings, the same or equivalent parts will be labeled with the same reference numerals, and their descriptions will not be repeated.

[0053] <Indium Phosphide Single Crystal Substrate>

[0054] First, the structure of the indium phosphide single crystal substrate 100 (hereinafter also referred to as InP single crystal substrate 100) of this embodiment will be described. Figure 1 This is a schematic top view showing the structure of the InP single crystal substrate 100 of this embodiment. Figure 2 This is a schematic side view illustrating the structure of the InP single-crystal substrate 100 according to this embodiment. Figure 1 and Figure 2 As shown, the InP single crystal substrate 100 has a first main surface 1, a second main surface 2, and an outer peripheral surface 3.

[0055] The first main surface 1 is, for example, planar. When viewed along a straight line perpendicular to the first main surface 1 (hereinafter also referred to as a top 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 a first direction 101 and a second direction 102, respectively.

[0056] The first primary surface 1 is the {100} plane of the single-crystal indium phosphide constituting the InP single-crystal substrate 100. The first direction 101 and the second direction 102 are respectively <011> Direction. The second direction 102 is 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.

[0057] like Figure 2 As shown, the second main surface 2 is opposite to the first main surface 1. The direction from the second main surface 2 towards the first main surface 1 is designated as the third direction 103. The third direction 103 is the growth direction of the InP single crystal when manufacturing the InP single crystal substrate 100. The third direction 103 is... <100> Direction. The outer peripheral surface 3 is connected to the first main surface 1 and the second main surface 2 respectively. The edge line between the first main surface 1 and the outer peripheral surface 3 is defined as the first outer edge 8. From another perspective, the first outer edge 8 is the outer edge of the first main surface 1.

[0058] like Figure 1 As shown, the diameter of the first main surface 1 is defined as a first diameter W1. The first diameter W1 is 150 mm or more and 303 mm or less. For example, the first diameter W1 can be 6 inches (152.4 mm) or more, or 200 mm or more. For example, the first diameter W1 can be less than 300 mm, less than 10 inches (254 mm), or less than 250 mm. The first diameter W1 is the longest distance between two different points on the first outer edge 8.

[0059] At least one of a notch, a positioning flat edge, or an indicator flat edge may be provided on the outer peripheral surface 3. When at least one of a notch, a positioning flat edge, or an indicator flat edge is provided on the outer peripheral surface 3, the center of the circle including the portion along the arc-shaped outer peripheral surface 3 is designated as the first center A1 when viewed from above.

[0060] <Dopant concentration of indium phosphide single crystal substrate>

[0061] The InP single crystal substrate 100 contains a dopant. The dopant is any one of sulfur (S), iron (Fe), and tin (Sn). Figure 3 This is a schematic top view showing the location where the dopant concentration of the InP single crystal substrate 100 was measured. (See attached image.) Figure 3As shown, the first main surface 1 has a first central rectangular region 10, a fifth outer rectangular region 15, and a sixth outer rectangular region 16. Each of the first central rectangular region 10, the fifth outer rectangular region 15, and the sixth outer rectangular region 16 is a region for measuring the dopant concentration. In top view, each of the first central rectangular region 10, the fifth outer rectangular region 15, and the sixth outer rectangular region 16 is rectangular in shape. The length of the short side of each of the first central rectangular region 10, the fifth outer rectangular region 15, and the sixth outer 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 rectangular region 15, and the sixth outer rectangular region 16 is, for example, 20 mm.

[0062] An imaginary line passing through the first center A1 and parallel to the first direction 101 is designated as the first imaginary line 91. An imaginary line passing through the first center A1 and parallel to the second direction 102 is designated as the second imaginary line 92. In a top-view perspective, the first central rectangular region 10, the fifth outer rectangular region 15, and the sixth outer rectangular region 16 are respectively located in the second direction 102 relative to the first imaginary line 91. In a top-view perspective, the first central rectangular region 10, the fifth outer rectangular region 15, and the sixth outer rectangular region 16 are respectively located in the first direction 101 relative to the second imaginary line 92.

[0063] When viewed from above, the corner of the first central rectangular region 10 coincides with the first center A1. When viewed from above, the shorter side of the first central rectangular region 10 coincides with the first imaginary line 91. When viewed from above, the longer side of the first central rectangular region 10 coincides with the second imaginary line 92.

[0064] 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 connected to the first outer edge 8. When viewed from above, the short side of the fifth outer rectangular region 15 coincides with the first imaginary straight line 91.

[0065] 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 connected to the first outer edge 8. When viewed from above, the short side of the sixth outer rectangular region 16 coincides with the second imaginary line 92.

[0066] Next, the method for determining the dopant concentration will be described. The dopant concentration is determined using, for example, glow discharge mass spectrometry (GDMS). In GDMS, a glow discharge mass spectrometer, such as the VG-9000 from VG-Elemental, can be used. In GDMS, a glow discharge plasma is generated using the analytical sample as the cathode under a high-purity argon atmosphere. By sputtering the surface of the analytical sample within this plasma, the constituent elements in the ionized analytical sample are determined using a mass spectrometer.

[0067] GDMS is performed, for example, according to the following steps. Specifically, firstly, the sample preparation section of the glow discharge mass spectrometer is cleaned to prevent and remove foreign matter. The sample preparation section is then pre-sputtered for, for example, 60 minutes. The analytical values ​​during pre-sputtering are set as background values.

[0068] After cutting or scribing along the outer edges of the first central rectangular region 10, the fifth outer rectangular region 15, and the sixth outer rectangular region 16, the InP single crystal substrate 100 is cleaved to prepare a strip-shaped sample for a needle-shaped sample cell. This needle-shaped sample cell serves as an ion source. The sample for the needle-shaped sample cell has a width of 2 mm, a length of 20 mm, and a thickness of 0.6 mm or more and 1 mm or less. During analysis, the needle-shaped sample cell clamping part is cooled using liquid nitrogen.

[0069] In GDMS, the following measurement conditions can be used, for example. Specifically, the diameter of the discharge surface is set to 10 mm. The discharge gas is argon gas with a purity of 6N. The discharge current is set to, for example, 2 mA. The discharge voltage is set to, for example, 1 kV. The glow discharge is set to constant current mode. The detector is a Faraday cup and a multiplier. The mass resolution (m / Δm) is set to approximately 4000 (high resolution mode). As for the relative sensitivity coefficient, a value built into the software accompanying the glow discharge mass spectrometer can be used, for example. The dopant concentration of the InP single crystal substrate 100 is determined using the above methods.

[0070] The dopant concentration of the first central rectangular region 10 is set as the first concentration. The first concentration is considered to be the dopant concentration of the first center A1 of the first main surface 1. The first concentration is, for example, 1 × 10⁻⁶. 16 cm -3 Above and 1×10 19 cm -3 the following.

[0071] The average dopant concentration of the fifth outer rectangular region 15 and the sixth outer rectangular region 16 is defined as the second concentration. This second concentration is considered to be the dopant concentration of the first outer edge 8 of the first main surface 1. The second concentration is, for example, 1 × 10⁻⁶. 16 cm-3 Above and 1×10 19 cm -3 the following.

[0072] The second concentration is, for example, lower than the first concentration. The absolute value of the first concentration minus the second concentration, divided by the first concentration (the first value), is less than 10%. The first value can be, for example, greater than 0.1% or greater than 1%. The first value can be, for example, less than 5% or less than 3%.

[0073] <Dislocation density of indium phosphide single crystal substrates>

[0074] In the InP single-crystal substrate 100 of this embodiment, dislocations exist. Furthermore, in this specification, "dislocation" is a type of crystal defect; in this art, a dislocation corresponds to an etch pit identified using the measurement method described later. Therefore, by measuring the number of these etch pits, the number of dislocations can be indirectly determined. In this specification, by measuring the number of etch pits per 1 cm... 2 The number of pits is used to determine the dislocation density.

[0075] Figure 4 This is a schematic top view showing the locations where the dislocation density of the InP single-crystal substrate 100 was measured. (See attached image.) Figure 4 As shown, the first main surface 1 has an outer peripheral region 18 and a central region 19. The outer peripheral region 18 is connected to the first outer edge 8. The central region 19 is surrounded by the outer peripheral region 18. The central region 19 is connected to the outer peripheral region 18. The radius of the central region 19 is set as a first radius R1. The radius of the first main surface 1 is set as a second radius R2. The second radius R2 is the first diameter W1 (reference). Figure 1 The value obtained by dividing the first radius R1 by 2. When the units for the first radius R1 and the second radius R2 are each mm, the first radius R1 is the integer value obtained by dividing the second radius R2 by 10, discarding the decimal point, and then multiplying 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.

[0076] like Figure 4 As shown, in the determination of dislocation density, the central region 19 is hypothetically divided into multiple square regions 5. Viewed from above, each of the multiple square regions 5 is substantially square in shape. The side length (first length L1) of each of the multiple square regions 5 is 10 mm.

[0077] First, imagine a square circumscribed around the central region 19 when viewed from above. The side length of this square is twice the first radius R1. This square is divided into 10mm × 10mm square regions. Within these square regions, the square region centered on the central region 19 is considered as multiple square regions 5 dividing the central region 19. Each of these multiple square regions 5 has one side parallel to the first direction 101. When viewed from above, within these multiple square regions 5, the corners of four of the square regions 5 coincide with the first center A1.

[0078] like Figure 4 As shown, the first main surface 1 has a central square region 17, a first outer rectangular region 11, a second outer rectangular region 12, a third outer rectangular region 13, and a fourth outer rectangular region 14. The central square region 17 contains the first center A1 of the first main surface 1. The side length of the central square region 17 is 40 mm. One side of the central square region 17 is parallel to the first direction 101. The central square region 17 contains 16 square regions 5.

[0079] 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 contains 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 located 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.

[0080] 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 periphery 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 the first radius R1. From another perspective, the outer periphery 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 at the boundary between the central region 19 and the outer peripheral region 18. Imagine a scenario where the distance between the outer edges 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 is defined as a first value, and the second radius R2 is defined as a second value, with the units of the first and second values ​​being mm. In this case, the first value is obtained by multiplying the integer value obtained by dividing the second value by 10 and discarding the decimal point, by 10.

[0081] Next, the method for measuring dislocation density will be described. First, a Huber etching solution is prepared. The Huber etching solution contains phosphoric acid and hydrogen bromide. The mass ratio of phosphoric acid to hydrogen bromide in the Huber etching solution is 2:1. The temperature of the Huber etching solution is set to, for example, 20°C. For example, an InP single crystal substrate 100 is immersed in the Huber etching solution for a period of 2 minutes to 7 minutes. As a result, etch pits are formed on the first main surface 1.

[0082] Next, each of the plurality of square regions 5 was observed using an optical microscope. Specifically, using an optical microscope, the number of pits in a 1 mm × 1 mm square measurement region centered on the center O of each of the plurality of square regions 5 was measured. The value obtained by dividing the measured number of pits by the area of ​​the square measurement region was set as the dislocation density of the square region 5.

[0083] The sum of the pit densities of the multiple square regions 5, divided by the number of square regions 5, is set as the dislocation density of the first principal surface 1. The dislocation density of the first principal surface 1 is 100 cm⁻¹. -2 The dislocation density of the first principal surface 1 can be, for example, 1 cm⁻¹. -2 The above can also be 10cm. -2 The dislocation density of the first principal surface 1 can be, for example, 60 cm⁻¹. -2 The following can also be 50cm -2 Below, it can also be 45cm-2 the following.

[0084] The sum of the pit densities of the individual square regions 5 contained in the central square region 17, divided by 16, is taken as the dislocation density (first density) of the central square region 17. The first density is considered to be the dislocation density of the first center A1 of the first main surface 1. The first density is, for example, 20 cm⁻¹. -2 Above and 70cm -2 the following.

[0085] The sum of the pit densities of the plurality of square regions 5 contained in 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, divided by 8, is respectively set as the dislocation density 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. The average value of the dislocation densities 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 set as the second density. The second density is considered to be the dislocation density of the first outer edge 8 of the first main surface 1. The second density is, for example, less than or equal to the first density. The second density is, for example, 20 cm. -2 Above and 120cm -2 the following.

[0086] The value obtained by dividing the second density by the first density (the second value A) is 267% or less. The second value A can be, for example, 75% or more, or 90% or more. The second value A can be, for example, 220% or less, 150% or less, or 125% or less.

[0087] The average of the dislocation densities of the first outer rectangular region 11 and the second outer rectangular region 12 is defined as the third density. The average of the dislocation densities of the third outer rectangular region 13 and the fourth outer rectangular region 14 is defined as the fourth density. The fourth density can be higher than the third density. The value obtained by dividing the fourth density by the third density (the second value B) is, for example, greater than 85% and less than 120%. The second value B can, for example, be greater than 90% or greater than 95%. The second value B can, for example, be less than 115% or less than 110%.

[0088] <Indium Phosphide Single Crystal>

[0089] Next, the structure of the indium phosphide single crystal 200 (hereinafter also referred to as InP single crystal 200) of this embodiment will be described. Figure 5 A schematic top view illustrating the structure of the InP single crystal 200 of this embodiment. Figure 6 A schematic side view illustrating the structure of the InP single crystal 200 according to this embodiment. Figure 5 and Figure 6 As shown, the InP single crystal 200 has a first end face 21, a second end face 22, and a cylindrical surface 23.

[0090] The first end face 21 is, for example, planar. When viewed along a straight line perpendicular to the first end face 21, the shape of the first end face 21 is, for example, circular. The first end face 21 includes a second center A2. The first end face 21 extends along a first direction 101 and a second direction 102, respectively. The first end face 21 is the {100} plane of the single crystal indium phosphide constituting the InP single crystal 200.

[0091] like Figure 6 As shown, the second end face 22 is opposite to the first end face 21. The direction from the second end face 22 toward the first end face 21 is the 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.

[0092] The length (second length L2) of the InP single crystal 200 on the third direction 103 is 50 mm or more and 150 mm or less. The second length L2 can be, for example, 70 mm or more or 90 mm or more. The second length L2 can be, for example, less than 140 mm or less or less than 130 mm.

[0093] The cylindrical surface 23 is connected to the first end surface 21 and the second end surface 22 respectively. The edge line of the first end surface 21 and the cylindrical surface 23 is designated as the second outer edge 28. The edge line of the second end surface 22 and the cylindrical surface 23 is designated as the third outer edge 29.

[0094] like Figure 5 As shown, the diameter of the first end face 21 is set as the second diameter W2. The second diameter W2 is 150 mm or more and 303 mm or less. For example, the second diameter W2 can be 6 inches (152.4 mm) or more, or 200 mm or more. For example, the second diameter W2 can be less than 300 mm, less than 10 inches (254 mm), or less than 250 mm. The second diameter W2 is the longest distance between two different points on the second outer edge 28.

[0095] At least one of a notch, a positioning flat edge, or an indicator flat edge may be provided on the cylindrical surface 23. When at least one of a notch, a positioning flat edge, or an indicator flat edge is provided on the cylindrical surface 23, the center of the circle including the part along the arc-shaped cylindrical surface 23 is designated as the second center A2 when viewed along a straight line perpendicular to the first end face 21.

[0096] <Dopant concentration of indium phosphide single crystal>

[0097] InP single crystal 200 contains dopants. The dopants are any one of sulfur (S), iron (Fe), and tin (Sn).

[0098] Figure 7 This is a schematic top view showing the location where the dopant concentration of the first end face 21 is measured. (See attached image.) Figure 7 As shown, the first end face 21 has a second central rectangular region 20, a seventh outer rectangular region 25, and an eighth outer rectangular region 26. Each of the second central rectangular region 20, the seventh outer rectangular region 25, and the eighth outer rectangular region 26 is a region for measuring the dopant concentration. Viewed along a straight line perpendicular to the first end face 21, each of the second central rectangular region 20, the seventh outer rectangular region 25, and the eighth outer rectangular region 26 is rectangular in shape. The length of the short side of each of the second central rectangular region 20, the seventh outer rectangular region 25, and the eighth outer 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 outer rectangular region 25, and the eighth outer rectangular region 26 is, for example, 20 mm.

[0099] An imaginary line passing through the second center A2 and parallel to the first direction 101 is designated as the third imaginary line 93. An imaginary line passing through the second center A2 and parallel to the second direction 102 is designated as the fourth imaginary line 94. Observing along a line perpendicular to the first end face 21, the second central rectangular region 20, the seventh outer rectangular region 25, and the eighth outer rectangular region 26 are located in the second direction 102 relative to the third imaginary line 93. Observing along a line perpendicular to the first end face 21, the second central rectangular region 20, the seventh outer rectangular region 25, and the eighth outer rectangular region 26 are located in the first direction 101 relative to the fourth imaginary line 94.

[0100] Observing along a line perpendicular to the first end face 21, the corner of the second central rectangular region 20 coincides with the second center A2. Observing along a line perpendicular to the first end face 21, the short side of the second central rectangular region 20 coincides with the third imaginary line 93. Observing along a line perpendicular to the first end face 21, the long side of the second central rectangular region 20 coincides with the fourth imaginary line 94.

[0101] 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 connected 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 coincides with the third imaginary line 93.

[0102] The eighth outer rectangular region 26 is located in the second direction 102 relative to the second central rectangular region 20. The eighth outer rectangular region 26 is connected 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 coincides with the fourth imaginary line 94.

[0103] Figure 8 This is a schematic bottom view showing the location where the dopant concentration of the second end face 22 is measured. (See diagram below.) Figure 8 As shown, the second end face 22 includes a third center A3. The second end face 22 has a third central rectangular region 30, a ninth outer rectangular region 35, and a tenth outer rectangular region 36. Each of the third central rectangular region 30, the ninth outer rectangular region 35, and the tenth outer rectangular region 36 is a region for measuring the dopant concentration. Viewed along a straight line perpendicular to the second end face 22, each of the third central rectangular region 30, the ninth outer rectangular region 35, and the tenth outer rectangular region 36 is rectangular in shape. The length of the short side of each of the third central rectangular region 30, the ninth outer rectangular region 35, and the tenth outer 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 outer rectangular region 35, and the tenth outer rectangular region 36 is, for example, 20 mm.

[0104] An imaginary line passing through the third center A3 and parallel to the first direction 101 is designated as the fifth imaginary line 95. An imaginary line passing through the third center A3 and parallel to the second direction 102 is designated as the sixth imaginary line 96. Observing along a line perpendicular to the second end face 22, the third central rectangular region 30, the ninth outer rectangular region 35, and the tenth outer rectangular region 36 are located in the second direction 102 relative to the fifth imaginary line 95. Observing along a line perpendicular to the second end face 22, the third central rectangular region 30, the ninth outer rectangular region 35, and the tenth outer rectangular region 36 are located in the first direction 101 relative to the sixth imaginary line 96.

[0105] Observing along a line perpendicular to the second end face 22, the corner of the third central rectangular region 30 coincides with the third center A3. Observing along a line perpendicular to the second end face 22, the short side of the third central rectangular region 30 coincides with the fifth imaginary line 95. Observing along a line perpendicular to the second end face 22, the long side of the third central rectangular region 30 coincides with the sixth imaginary line 96.

[0106] The ninth outer rectangular region 35 is located in the first direction 101 relative to the third central rectangular region 30. The ninth outer rectangular region 35 is connected 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 coincides with the fifth imaginary line 95.

[0107] The tenth outer rectangular region 36 is located in the second direction 102 relative to the third central rectangular region 30. The tenth outer rectangular region 36 is connected 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 coincides with the sixth imaginary line 96.

[0108] Next, the method for measuring the dopant concentration will be described. The dopant concentration is measured using the GDMS described above. The GDMS is performed, for example, according to the steps 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 face 21 and a second wafer having a second end face 22. The structures of the first and second wafers are substantially the same as the structure of the InP single crystal substrate 100. The first end face 21 of the first wafer corresponds to the first main surface 1. The second end face 22 of the second wafer corresponds to the second main surface 2.

[0109] After cutting or scribing along the outer edges of the second central rectangular region 20, the seventh outer rectangular region 25, and the eighth outer rectangular region 26, the first wafer is cleaved. Similarly, after cutting or scribing along the outer edges of the third central rectangular region 30, the ninth outer rectangular region 35, and the tenth outer rectangular region 36, the second wafer is cleaved. Through these operations, a needle-shaped sample cell is prepared. This needle-shaped sample cell serves as an ion source. The measurement conditions described above can be used as the GDMS measurement conditions. The dopant concentration of the InP single crystal 200 is measured using the above method.

[0110] The dopant concentration of the second central rectangular region 20 is set as the third concentration. The third concentration is considered to be the dopant concentration of the second center A2 of the first end face 21. The third concentration is, for example, 1 × 10⁻⁶. 17 cm -3 Above and 1×10 19 cm -3 the following.

[0111] The average dopant concentration of the seventh outer rectangular region 25 and the eighth outer rectangular region 26 is defined as the fourth concentration. The fourth concentration is considered to be the dopant concentration of the second outer edge 28 of the first end face 21. The fourth concentration is, for example, 1 × 10⁻⁶. 17 cm -3 Above and 1×10 19 cm -3 the following.

[0112] The fourth concentration is, for example, lower than the third concentration. The absolute value of the third concentration minus the fourth concentration, divided by the third concentration (the third value), is less than 10%. The third value can be, for example, greater than 0.1% or greater than 1%. The third value can be, for example, less than 5% or less than 3%.

[0113] The dopant concentration in the third central rectangular region 30 is set as the fifth concentration. The fifth concentration is considered to be the dopant concentration of the third center A3 of the second end face 22. The fifth concentration is, for example, 1 × 10⁻⁶. 16 cm -3 Above and 5×10 18 cm -3 the following.

[0114] The average dopant concentration of the ninth outer rectangular region 35 and the tenth outer rectangular region 36 is defined as the sixth concentration. The sixth concentration is considered to be the dopant concentration of the third outer edge 29 of the second end face 22. The sixth concentration is, for example, 1 × 10⁻⁶. 16 cm -3 Above and 5×10 18 cm -3 the following.

[0115] The sixth concentration is, for example, lower than the fifth concentration. The absolute value of the fifth concentration minus the sixth concentration, divided by the fifth concentration (the fourth value), is less than 10%. The fourth value can be, for example, greater than 0.1% or greater than 1%. The fourth value can be, for example, less than 5% or less than 3%.

[0116] The dopant concentration of the first end face 21 can be higher than that of the second end face 22. Specifically, the third concentration can be higher than the fifth concentration. The fourth concentration can be higher than the sixth concentration.

[0117] <Dislocation density of indium phosphide single crystals>

[0118] In the InP single crystal 200 of this embodiment, dislocations are present. The dislocation density of the first end face 21 and the dislocation density of the second end face 22 are measured using the same method as the method for measuring the dislocation density of the first main surface 1 described above. Specifically, similar to the method for measuring dopant concentration described above, a first wafer having the first end face 21 and a second wafer having the second end face 22 are prepared by cutting the InP single crystal 200. The same method as the method for measuring the dislocation density of the first main surface 1 described above is performed on the first end face 21 of the first wafer and the second end face 22 of the second wafer.

[0119] Similarly, the dislocation density of the second center A2 of the first end face 21 and the dislocation density of the third center A3 of the second end face 22 are measured using the same method as the method for measuring the dislocation density (first density) of the first center A1 of the first main surface 1 described above. Specifically, for the first end face 21 and the second end face 22, the dislocation density of the region corresponding to the central square region 17 described above is measured respectively.

[0120] Similarly, the dislocation density of the second outer edge 28 of the first end face 21 and the dislocation density of the third outer edge 29 of the second end face 22 are measured using the same method as the method for measuring the dislocation density (second density) of the first outer edge 8 of the first main surface 1 described above. Specifically, for the first end face 21 and the second end face 22, the dislocation density of the regions corresponding to the first outer perimeter rectangular region 11, the second outer perimeter rectangular region 12, the third outer perimeter rectangular region 13, and the fourth outer perimeter rectangular region 14 described above are measured respectively.

[0121] At least one of the dislocation density of the first end face 21 and the dislocation density of the second end face 22 is 100cm. -2 The dislocation density of the first end face 21 can be, for example, 1 cm⁻¹. -2 The above can also be 10cm. -2 The dislocation density of the first end face 21 can be, for example, 80 cm⁻¹. -2 The following can also be 65cm -2 Below, it can also be 55cm -2 The dislocation density of the second end face 22 can be, for example, 1 cm⁻¹. -2 The above can also be 10cm. -2 The dislocation density at the second end face 22 can be, for example, 85 cm⁻¹. -2 The following can also be 55cm -2 Below, it can also be 45cm -2 the following.

[0122] <Indium phosphide single crystal substrate manufacturing equipment>

[0123] Next, the structure of the InP single crystal growth apparatus 300 of this embodiment will be described. Figure 9 This is a schematic cross-sectional view illustrating the structure of the InP single crystal 200 growth apparatus 300 according to this embodiment. Figure 9 As shown, the growth apparatus 300 for InP single crystal 200 mainly includes a crucible 40, an inner cylinder 50, a crucible support 60, a first axis 55, a second axis 56, and a heating element 48.

[0124] The crucible 40 is made of a material capable of withstanding heating when the molten raw material is heated. Specifically, the crucible 40 is made of, for example, pyrolytic boron nitride (pBN). The crucible 40 is cylindrical with a bottom. The central axis X of the crucible 40 extends along a third direction 103. The crucible 40 has a seed crystal receiving portion 41, an expanded diameter portion 42, and a straight cylindrical portion 43.

[0125] The seed crystal receiving portion 41 is cylindrical with a bottom. The seed crystal receiving portion 41 is the portion where the seed crystal is disposed. The seed crystal receiving portion 41 opens towards a third direction 103. The seed crystal receiving portion 41 has a bottom 41a and an outer peripheral portion 41b.

[0126] The bottom 41a forms the bottom of the crucible 40. The central axis X passes through the bottom 41a. The outer peripheral portion 41b is connected to the bottom 41a. The outer peripheral portion 41b is annular in shape. The outer peripheral portion 41b surrounds the central axis X. The outer peripheral portion 41b is positioned on a third direction 103 relative to the bottom 41a. When viewed along the third direction 103, the outer peripheral portion 41b has a circular shape.

[0127] The diameter-enlarging portion 42 is connected to the seed crystal receiving portion 41. Specifically, the diameter-enlarging portion 42 is connected to the outer peripheral portion 41b. The diameter-enlarging portion 42 is disposed on the third direction 103 relative to the seed crystal receiving portion 41. The diameter-enlarging portion 42 is annular in shape. The diameter-enlarging portion 42 surrounds the central axis X. As it moves away from the seed crystal receiving portion 41 along the third direction 103, the outer diameter of the diameter-enlarging portion 42 increases. Similarly, as it moves away from the seed crystal receiving portion 41 along the third direction 103, the inner diameter of the diameter-enlarging portion 42 increases.

[0128] The straight cylindrical portion 43 is connected to the expanded diameter portion 42. The straight cylindrical portion 43 is disposed on the third third direction 103 relative to the expanded diameter portion 42. From another viewpoint, the straight cylindrical portion 43 is positioned opposite the seed crystal receiving portion 41 relative to the expanded diameter portion 42. The straight cylindrical portion 43 is annular in shape. When viewed along the third third direction 103, the outer shape of the straight cylindrical portion 43 is circular. The straight cylindrical portion 43 surrounds the central axis X. The inner diameter D of the straight cylindrical portion 43 is, for example, 150 mm or more and 350 mm or less.

[0129] Heating element 48 heats crucible 40. Specifically, heating element 48 heats crucible 40 by, for example, supplying electricity to heating element 48. Heating element 48 is cylindrical in shape. Heating element 48 surrounds crucible 40. Heating element 48 is separate from crucible 40. 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. Second heating element portion 48b is disposed in a fourth direction 104 relative to first heating element portion 48a. Third heating element portion 48c is disposed in the fourth direction 104 relative to second heating element portion 48b. Fourth direction 104 is the direction opposite to third direction 103. Growth apparatus 300 is configured to individually control the electricity supplied to the first heating element portion 48a, second heating element portion 48b, and third heating element portion 48c.

[0130] A crucible support 60 supports a crucible 40. The crucible support 60 is positioned in a fourth direction 104 relative to the crucible 40. A first shaft 55 is mounted on the crucible support 60. The first shaft 55 is positioned in the fourth direction 104 relative to the crucible support 60. The first shaft 55 extends along a third direction 103. The central axis of the first shaft 55 substantially coincides with the central axis X. The first shaft 55 is configured to be rotatable about the central axis X. From another viewpoint, the crucible 40 is configured to be rotatable about the central axis X. The first shaft 55 is configured to be movable in a direction parallel to the third direction 103. From another viewpoint, the crucible 40 is configured to be movable in a direction parallel to the third direction 103.

[0131] The inner cylinder 50 is disposed inside the crucible 40. The inner cylinder 50 is surrounded by a straight cylindrical portion 43. The inner cylinder 50 is, for example, cylindrical. The inner cylinder 50 is solid. The inner cylinder 50 is made of, for example, quartz or carbon coated with pBN. The inner cylinder 50 has a lower end 51, an upper end 52, and side surfaces 53.

[0132] The lower end 51 faces the bottom 41a. When viewed along the third direction 103, the lower end 51 is circular in shape. The diameter of the lower end 51 (the 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 cylindrical 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 can, for example, be 20 mm or more or 30 mm or more. The difference between the third diameter W3 and the inner diameter D can, for example, be 80 mm or less, 55 mm or less, or 35 mm or less.

[0133] The upper end 52 is positioned relative to the lower end 51 on the third direction 103. When viewed along the fourth direction 104, the upper end 52 is circular in shape. The diameter of the upper end 52 (the fourth diameter W4) can, for example, be the same as the third diameter W3. The side end 53 is connected to both the lower end 51 and the upper end 52. The side end 53 extends along the third direction 103. When viewed along the third direction 103, the side end 53 is, for example, circular in shape. The diameter of the side end 53 can be substantially the same as the third diameter W3.

[0134] At the upper end 52, a second shaft 56 is mounted on the inner cylinder 50. The second shaft 56 is positioned relative to the inner cylinder 50 in a third direction 103. The second shaft 56 extends along the third direction 103. The central axis of the second shaft 56 substantially coincides with the central axis X. The second shaft 56 is configured to rotate about the central axis X. From another viewpoint, the inner cylinder 50 is configured to rotate about the central axis X. From yet another viewpoint, the inner cylinder 50 and the crucible 40 are configured to rotate relative to each other. The second shaft 56 is configured to move in a direction parallel to the third direction 103. From another viewpoint, the inner cylinder 50 is configured to move in a direction parallel to the third direction 103.

[0135] <Method for manufacturing indium phosphide single crystals>

[0136] Next, the manufacturing method of the InP single crystal 200 of this embodiment will be described. The InP single crystal 200 is manufactured using the 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 combining the VB method and the VGF method.

[0137] Figure 10 This is a flowchart that schematically illustrates the manufacturing method of the InP single crystal 200 according to this embodiment. (As shown...) Figure 10 As shown, the manufacturing method of InP single crystal 200 in this embodiment mainly includes: a step of preparing a growth apparatus (S10), a step of preparing a seed crystal (S20), a step of preparing indium phosphide raw material and sealing material (S30), a step of melting the raw material (S40), a step of inserting the inner cylinder into the indium phosphide molten liquid (S50), a step of growing the crystal (S60), and a step of cutting the crystal (S70).

[0138] First, the process of preparing the growth apparatus is carried out (S10). Figure 11 This is a schematic partial cross-sectional view showing the process (S10) of preparing the growth apparatus 300. (See diagram below.) Figure 11As shown, the growth apparatus 300 of this embodiment is prepared. In the step (S10) of preparing the growth apparatus, the inner cylinder 50 is disposed outside the crucible 40. For ease of explanation, in Figure 11 The inner cylinder 50 and the second shaft 56 are not shown in the figure.

[0139] Next, the process of preparing seed crystals is carried out (S20). Figure 12 This is a schematic cross-sectional view showing a crucible 40 containing a seed crystal 84, indium phosphide raw material 85, and sealing material 86. (See diagram below.) Figure 12 As shown, in the seed crystal preparation step (S20), a seed crystal 84 is disposed inside the seed crystal receiving portion 41. The seed crystal 84 is made of single-crystal indium phosphide. The seed crystal 84 may also contain any one of sulfur, iron, and tin as impurity atoms.

[0140] Next, the process of preparing indium phosphide raw materials and sealing materials is carried out (S30). For example... Figure 12 As shown, multiple indium phosphide raw materials 85 (hereinafter also referred to as InP raw materials 85) are disposed on a seed crystal 84. Each of the multiple InP raw materials 85 is composed of, for example, polycrystalline indium phosphide. The respective shape of the multiple InP raw materials 85 is, for example, cylindrical. The multiple InP raw materials 85 are stacked on the seed crystal 84. The weight of the multiple InP raw materials 85 is, for example, 10 kg. Any one of sulfur, iron, and tin as impurities is disposed inside the crucible 40.

[0141] Next, sealing material 86 is disposed on a plurality of InP raw materials 85. Sealing material 86 is composed of, for example, boron oxide (B₂O₃). Sealing material 86 is cylindrical in shape. The weight of sealing material 86 is, for example, 2850 g.

[0142] Next, the process of melting the raw material is carried out (S40). 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, as the crucible 40 moves away from the bottom 41a along the third direction 103, the temperature of the crucible 40 increases. As a result, a portion of the seed crystal 84 and the InP raw material 85 melt.

[0143] Figure 13 This is a schematic cross-sectional view showing the process (S40) of molten raw materials. For example... Figure 13 As shown, a portion of the molten seed crystal 84 and the molten InP raw material 85 become indium phosphide melt 87 (hereinafter also referred to as InP melt 87). Thus, InP melt 87 is prepared. InP melt 87 comes into contact with the remaining portion of the seed crystal 84. Through the melting of sealing material 86, sealing material 86 becomes liquid sealing material 88. Liquid sealing material 88 covers InP melt 87.

[0144] Next, the process of inserting the inner cylinder into the molten indium phosphide is carried out (S50). Figure 14 This is a schematic cross-sectional view showing the process (S50) of inserting the inner cylinder into molten indium phosphide. Figure 14 As shown, the inner cylinder 50 is moved along the fourth direction 104 using the second shaft 56, thereby inserting the inner cylinder 50 into the InP molten liquid 87 inside the crucible 40. The lower end 51 is located in the fourth direction 104 relative to the straight cylinder portion 43. The lower end 51 is surrounded by the diameter-enlarging portion 42. The upper end 52 is located in the third direction 103 relative to the straight cylinder portion 43. The inner cylinder 50 is located in the third direction 103 relative to the seed crystal 84. The InP molten liquid 87 is located between the inner cylinder 50 and the straight cylinder portion 43. The InP molten liquid 87 is located between the inner cylinder 50 and the diameter-enlarging portion 42.

[0145] Next, the process of growing crystals is carried out (S60). Figure 15 This is a schematic cross-sectional view showing the crystal growth process (S60). For example... Figure 15 As shown, the crucible 40 rotates, for example, about the central axis X along arrow C. The inner cylinder 50 is, for example, stationary. Thus, the crucible 40 rotates relative to the inner cylinder 50. The relative rotational speed of the crucible 40 relative to the inner cylinder 50 is, for example, 20 rpm or more and less than 200 rpm. The relative rotational speed of the crucible 40 relative to the inner cylinder 50 can, for example, be 40 rpm or more, or 80 rpm or more. The relative rotational speed of the crucible 40 relative to the inner cylinder 50 can, for example, be 160 rpm or less, or 120 rpm or less. This causes flow in the InP molten liquid 87. Therefore, the InP molten liquid 87 is stirred.

[0146] The crucible 40 rotates relative to the inner cylinder 50 and moves along the fourth direction 104. As a result, the temperature of the portion of the InP molten liquid 87 near the remaining portion of the seed crystal 84 decreases. The moving speed of the crucible 40 in the fourth direction 104 is set, for example, to be more than 2 mm / h and less than 5 mm / h. Indium phosphide crystal 210 (hereinafter also referred to as InP crystal 210) grows as the InP molten liquid 87 in contact with the remaining portion of the seed crystal 84 solidifies.

[0147] In the crystal growth process (S60), an interface (solid-liquid interface I) is formed between the InP crystal 210 and the InP molten liquid 87. The solid-liquid interface I protrudes in the third direction 103. The longest distance between two different points on the solid-liquid interface I in the third direction 103 is defined as the height H of the solid-liquid interface I. The value obtained by dividing the height H by the inner diameter D (convexity) is, for example, 1%. The convexity can be, for example, 0% or more and less than 3%. If the convexity is too large, the InP molten liquid 87 closer to the central axis X solidifies prematurely compared to the InP molten liquid 87 farther from the central axis X. In this case, dopant segregation occurs, and the deviation of the dopant concentration in the InP single crystal 200 increases. By making the convexity less than 3%, the deviation of the dopant concentration in the InP single crystal 200 can be reduced. The stirring of the inner cylinder 50 has the effect of reducing the radial temperature difference within the InP molten liquid 87, which can reduce the convexity of the solid-liquid interface I. By stirring the molten liquid in the inner cylinder 50, the convexity is reduced to less than 3%, thereby lowering the dislocation density of the InP single crystal 200. Furthermore, the radial direction is perpendicular to the central axis X and extends from the central axis X toward the crucible 40. The shortest distance E between the solid-liquid interface I on the third direction 103 and the lower end 51 is, for example, 5 mm or more and 20 mm or less.

[0148] As the crucible 40 continues to move, the InP molten liquid 87 inside the crucible 40 solidifies. This produces an InP crystal 210. The maximum diameter of the InP crystal 210 is substantially the same as the inner diameter D of the cylindrical portion 43.

[0149] Next, the process of cutting the crystal is performed (S70). InP single crystal 200 is manufactured by cutting the InP crystal 210 using, for example, a wire saw (see reference). Figure 5 and Figure 6 Alternatively, the InP single crystal substrate 100 can also be manufactured by cutting the InP crystal 210 in the crystal cutting process (S70) (see reference). Figure 1 and Figure 2 ).

[0150] Next, the effects of the InP single crystal substrate 100, InP single crystal 200, and the manufacturing method of InP single crystal 200 of the present invention will be explained.

[0151] The dislocation density and dopant concentration of the InP single-crystal substrate 100 affect the yield of semiconductor devices manufactured using the InP single-crystal substrate 100. Specifically, for example, when manufacturing semiconductor devices such as optical sensors using the InP single-crystal substrate 100, semiconductor devices manufactured using an InP single-crystal substrate 100 with excessively high dislocation density sometimes experience excessively high dark current. In this case, the signal-to-noise ratio (SNR) sometimes deteriorates. As a result, the yield of the semiconductor device decreases. If the deviation in dopant concentration on the main surface of the InP single-crystal substrate 100 is too large, the characteristic deviation of the semiconductor device manufactured using the InP single-crystal substrate 100 increases. As a result, the yield of the semiconductor device decreases.

[0152] The inventors investigated methods to improve the yield of semiconductor devices and obtained the following insights. Specifically, the inventors focused on the temperature distribution of the InP melt 87 during the growth process of InP single crystal 200. Specifically, during the growth of InP single crystal 200, temperature deviations sometimes occur in the InP melt 87 perpendicular to the growth direction. In this case, solidification occurs from the portion of the InP melt 87 with the lower temperature, resulting in dopant segregation in the InP single crystal 200. As a result, the deviation in dopant concentration of the InP single crystal 200 becomes excessively large. Furthermore, when the temperature fluctuation of the InP melt 87 becomes excessively large, twinning (double crystals) is easily generated, reducing the single crystal yield. At this time, when growth is carried out under conditions of large temperature gradient in order to suppress twinning caused by temperature fluctuations, the dislocation density of the InP single crystal 200 increases.

[0153] Based on the above insights, the inventors conceived of a method for stirring the InP molten liquid 87. Specifically, they conceived of inserting the inner cylinder 50 into the InP molten liquid 87 and then rotating the inner cylinder 50 relative to the crucible 40. By rotating the inner cylinder 50 relative to the crucible 40, a flow such as Taylor eddies is generated in the InP molten liquid 87. Taylor eddies are highly resistant to interference. Therefore, even if temperature fluctuations occur in the InP molten liquid 87, it is possible to stably stir the InP molten liquid 87. By using this flow to stir the InP molten liquid 87, the temperature deviation and radial temperature difference of the InP molten liquid 87 can be reduced. As a result, the deviation in dopant concentration of the InP single crystal 200 can be reduced, and the solid-liquid interface I does not need to be excessively convex as a countermeasure against twinning, thus reducing the dislocation density of the InP single crystal 200.

[0154] According to the manufacturing method of InP single crystal 200 of this embodiment, the InP molten liquid 87 is solidified by rotating the crucible 40 relative to the inner cylinder 50 while moving the crucible 40. Therefore, due to the relative rotation between the inner cylinder 50 and the crucible 40, flow is generated in the InP molten liquid 87. This allows for effective stirring of the InP molten liquid 87. Consequently, the temperature deviation and radial temperature difference of the InP molten liquid 87 can be reduced. Therefore, in the InP single crystal 200, the deviation of dopant concentration and dislocation density can be reduced. Therefore, on the main surface of the InP single crystal substrate 100 manufactured using the InP single crystal 200, the deviation of dopant concentration and dislocation density can be reduced. As a result, the yield of semiconductor devices can be improved.

[0155] When the difference between the diameter of the lower end of the inner cylinder 50 and the inner diameter of the straight cylindrical portion 43 of the crucible 40 is too large, the flow generated by the relative rotation between the inner cylinder 50 and the crucible 40 cannot adequately stir the InP molten liquid 87. According to the manufacturing method of 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 cylindrical portion 43 of the crucible 40 is 110 mm or less. Therefore, the InP molten liquid 87 can be adequately stirred. Consequently, in the InP single crystal 200, the deviation in dopant concentration and dislocation density can be reduced.

[0156] If the difference between the diameter at the lower end of the inner cylinder 50 and the inner diameter of the straight cylindrical portion 43 of the crucible 40 is too small, the volume (feed amount) of InP raw material 85 that can be filled into the crucible 40 becomes too small. In this case, the productivity of InP single crystal 200 decreases. According to the manufacturing method of InP single crystal 200 in this embodiment, the difference between the diameter at the lower end of the inner cylinder 50 and the inner diameter of the straight cylindrical portion 43 of the crucible 40 is 10 mm or more. Therefore, the decrease in the productivity of InP single crystal 200 can be suppressed.

[0157] Sometimes, the temperature distribution of the InP melt 87 is reduced by decreasing the convexity of the InP melt 87. In this case, due to compositional supercooling caused by solidification segregation of the InP melt 87, twins are easily generated at the outer peripheral facet of the InP single crystal 200. According to the InP single crystal 200 of this embodiment, the InP melt 87 can be sufficiently stirred, thus suppressing compositional supercooling of the InP melt 87 and reducing temperature fluctuations within the melt. As a result, the generation of twins in the InP single crystal 200 can be suppressed.

[0158] By appropriately setting the difference between the diameter of the lower end of the inner cylinder 50 and the inner diameter of the straight cylindrical portion 43 of the crucible 40, Taylor vortices can be generated more reliably in the InP molten liquid 87. Therefore, the InP molten liquid 87 can be stirred more effectively. According to the manufacturing method of 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 cylindrical portion 43 of the crucible 40 is 55 mm or less. Therefore, Taylor vortices can be generated more reliably in the InP molten liquid 87. Thus, the InP molten liquid 87 can be stirred more effectively.

[0159] By appropriately setting the relative rotational speed of the crucible 40 relative to the inner cylinder 50, Taylor eddies can be generated more reliably in the InP molten liquid 87. On the other hand, if the relative rotational speed of the crucible 40 relative to the inner cylinder 50 is too fast, turbulence is generated in the InP molten liquid 87, which easily leads to twinning. According to the manufacturing method of the InP single crystal 200 of this embodiment, the relative rotational speed of the crucible 40 relative to the inner cylinder 50 is 20 rpm or more and less than 200 rpm. Therefore, Taylor eddies can be generated more reliably in the InP molten liquid 87. As a result, the InP molten liquid 87 can be stirred more effectively.

[0160] According to the manufacturing method of the InP single crystal 200 in this embodiment, the inner cylinder 50 is solid. Therefore, the heat capacity of the inner cylinder 50 can be sufficiently increased. Thus, compared with the case where the inner cylinder 50 is hollow, when the heat energy applied to the crucible 40 by the heating element 48 changes due to the movement of the crucible 40, the temperature fluctuation of the InP molten liquid 87 can be suppressed.

[0161] According to the InP single-crystal substrate 100 of this embodiment, the dislocation density on the first main surface 1 is 100 cm⁻¹. -2 The absolute value of the first concentration minus the second concentration, divided by the first concentration, is less than 10%. In this way, the dislocation density of the first main surface 1 is sufficiently reduced, and the deviation in dopant concentration of the first main surface 1 is sufficiently reduced. Therefore, the yield of semiconductor devices manufactured using the InP single-crystal substrate 100 can be improved.

[0162] According to the InP single-crystal substrate 100 of this embodiment, the value obtained by dividing the second density by the first density is 267% or less. In this way, the deviation in dislocation density on the first main surface 1 is sufficiently reduced. Therefore, the yield of semiconductor devices manufactured using the InP single-crystal substrate 100 can be improved.

[0163] According to the InP single-crystal substrate 100 of this embodiment, the diameter of the first main surface 1 is 150 mm or more. In this way, even when the InP single-crystal substrate 100 has a large diameter, the dislocation density of the first main surface 1 is sufficiently reduced, and the deviation in dopant concentration of the first main surface 1 is also sufficiently reduced. Therefore, the yield of semiconductor devices manufactured using the InP single-crystal substrate 100 can be further improved.

[0164] According to the InP single-crystal substrate 100 of this embodiment, the first main surface 1 is a {100} plane. From another viewpoint, the growth direction of the InP single-crystal substrate 100 is... <100> Direction. Compared to the case where the growth direction is <111>, InP single crystals are more prone to twinning when the growth direction is <100>. According to the InP single crystal substrate 100 of this embodiment, even if the growth direction is <111>, twinning is more likely to occur in InP single crystal substrates with a growth direction of <100>. <100> Direction can also suppress the formation of twins.

[0165] According to the InP single crystal 200 of this embodiment, at least one of the dislocation density of the first end face 21 and the dislocation density of the second end face 22 is 100 cm⁻¹. -2 The absolute value of the third concentration minus the fourth concentration, divided by the third concentration, is less than 10%. Similarly, the absolute value of the fifth concentration minus the sixth concentration, divided by the fifth concentration, is less than 10%. In this way, the dislocation density is sufficiently reduced, and the deviation in dopant concentration between the first end face 21 and the second end face 22 is sufficiently reduced. Therefore, the yield of semiconductor devices manufactured using InP single crystal 200 can be improved.

[0166] (Modified Example)

[0167] Next, a modified example of the manufacturing method of InP single crystal 200 according to this embodiment will be described. Figure 16 This is a schematic partial cross-sectional view illustrating the structure of the InP single crystal 200 growth apparatus 300 in a first modified example of this embodiment. Figure 16 As shown, the inner cylinder 50 can be truncated cone-shaped. From another perspective, the diameter of the side 53 can decrease as it moves away from the lower end 51 along the third direction 103. From yet another perspective, the diameter of the lower end 51 (third diameter W3) can be larger than the diameter of the upper end 52 (fourth diameter W4). In other words, the fourth diameter W4 can be smaller than the third diameter W3. By having the fourth diameter W4 larger than the third diameter W3, compared to the case where the third diameter W3 and the fourth diameter W4 are the same, the volume (charge amount) of the InP molten liquid 87 disposed inside the crucible 40 can be increased. Therefore, the length (second length L2) of the InP single crystal 200 can be increased.

[0168] Figure 17This is a schematic partial cross-sectional view showing the structure of the InP single crystal 200 growth apparatus 300 in a second modified example of this embodiment. Figure 17 As shown, the inner cylinder 50 may have a receiving portion 57 and a filling member 58. The receiving portion 57 is cylindrical with a bottom. The receiving portion 57 constitutes each of the lower end 51, the upper end 52, and the side 53. The receiving portion 57 is made of quartz or carbon coated with pBN. The filling member 58 fills the interior of the receiving portion 57. From another perspective, the contents of the inner cylinder 50 are constituted by the filling member 58. The filling member 58 is made of, for example, polycrystalline indium phosphide. In the step of preparing the growth apparatus (S10), the filling member 58 is, for example, cylindrical. In the step of inserting the inner cylinder into the indium phosphide molten liquid (S50), the filling member 58 may be melted. In the step of crystal growth (S60), the filling member 58 is separated from the InP molten liquid 87 by the receiving portion 57.

[0169] By using indium phosphide for the filling member 58, the difference in thermal conductivity between the molten InP 87 and the inner cylinder 50 can be reduced. This helps to suppress temperature fluctuations in the molten InP 87 when the crucible 40 moves. Furthermore, a space can be provided between the filling member 58 and the receiving portion 57.

[0170] Furthermore, in the crystal growth step (S60) of the InP single crystal 200 manufacturing method of this embodiment, the inner cylinder 50 can rotate about the central axis X. Specifically, both the inner cylinder 50 and the crucible 40 can rotate, or only one of the inner cylinder 50 and the crucible 40 can rotate. In the crystal growth step (S60), it is sufficient to rotate the crucible 40 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 rotate, the rotation direction of the inner cylinder 50 and the rotation direction of the crucible 40 can be the same or different.

[0171] Example

[0172] <Sample Preparation>

[0173] First, InP single crystal 200 samples 1 to 13 were prepared. InP single crystal 200 samples 1 to 4 were used as comparative examples. InP single crystal 200 samples 5 to 13 were used as exemplary examples. The InP single crystal 200 samples 1 to 13 were manufactured according to the InP single crystal 200 manufacturing method described above. Specifically, the InP single crystal 200 was manufactured using the conditions shown in Table 1 below.

[0174] [Table 1]

[0175]

[0176] Table 1 shows the manufacturing conditions of InP single crystal 200 for samples 1 to 13. As shown in Table 1, in samples 1 to 10, 12, and 13, the diameter of the first end face 21 (second diameter W2) is 152 mm. In sample 11, the second diameter W2 is 303 mm. In samples 1 to 11, the dopant is sulfur. In sample 12, the dopant is iron. In sample 13, the dopant is tin.

[0177] In samples 1 and 2, the convexity of solid-liquid interface I is 10%. In samples 3 and 4, the convexity of solid-liquid interface I is 3%. In samples 5 to 13, the convexity of solid-liquid interface I is 1%.

[0178] 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 inner cylinder 50 was cylindrical. In samples 5 to 13, the diameter of the lower end of the inner cylinder 50 (the 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 (the third diameter W3) was 31 mm or more and 106 mm or less.

[0179] In samples 1 and 3, the rotational speed of crucible 40 is 2 rpm. In samples 2 and 4, the rotational speed of crucible 40 is 200 rpm. In samples 5 to 13, crucible 40 rotates relative to inner cylinder 50 while inner cylinder 50 remains stationary. In samples 5 to 13, the rotational speed of crucible 40 is between 10 rpm and 150 rpm. Alternatively, in samples 5 to 13, the relative rotational speed between inner cylinder 50 and crucible 40 is between 10 rpm and 150 rpm.

[0180] In samples 1 to 10, 12, and 13, the inner diameter D of crucible 40 is 156 mm. In sample 11, the inner diameter D of crucible 40 is 307 mm. The weight of InP raw material 85 is 10 kg. The weight of sealing material 86 is 2850 g. In the crystal growth process (S60), the moving speed of crucible 40 in the fourth direction 104 is 2.5 mm / h.

[0181] <Experimental Methods>

[0182] In InP single crystals 200 from samples 1 to 13, the presence or absence of twins was confirmed. The dopant concentration was measured at the first end face 21 and the second end face 22 using the dopant concentration measurement method described above. Specifically, at the first end face 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 third concentration minus the fourth concentration was calculated and divided by the third concentration (third value). At the second end face 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 fifth concentration minus the sixth concentration was calculated and divided by the fifth concentration (fourth value). GDMS was used in the dopant concentration measurement. The measurement conditions described above were used in the GDMS.

[0183] In samples 1 to 13, the dislocation density of the first end face 21 and the dislocation density of the second end face 22 were measured using the dislocation density measurement method described above. The first density described above was measured in both the first end face 21 and the second end face 22. Specifically, the dislocation density of the region corresponding to the central square region 17 described above was measured in both the first end face 21 and the second end face 22.

[0184] The aforementioned third density was measured on the first end face 21 and the second end face 22, respectively. Specifically, for the first end face 21 and the second end face 22, the dislocation density of the regions corresponding to the first outer perimeter rectangular region 11 and the second outer perimeter rectangular region 12, respectively, was measured.

[0185] The aforementioned fourth density was measured on the first end face 21 and the second end face 22, respectively. Specifically, for the first end face 21 and the second end face 22, the dislocation density of the regions corresponding to the aforementioned third outer perimeter rectangular region 13 and fourth outer perimeter rectangular region 14 was measured, respectively. Using the first density, the third density, and the fourth density, the aforementioned second value A and the second value B of the first end face 21 and the second end face 22 were calculated, respectively.

[0186] [Table 2]

[0187]

[0188] Table 2 shows the results of the determination of the presence or absence of twins and the dopant concentration in InP single crystal 200 samples 1 to 13. As shown in Table 2, twins were generated in samples 5 and 9 of the examples. No twins were generated in samples 6 to 8 and 10 to 13.

[0189] In samples 1 to 4, the fourth value was above 10%. The third value was above 10%. In samples 5 to 13, the fourth value was below 9.5%. The third value was below 9.5%.

[0190] [Table 3]

[0191]

[0192] Table 3 shows the results of dislocation density measurements for InP single crystal 200 samples 1 to 13. In Table 3, "ND" indicates that the dislocation density could not be measured because twins were generated in the InP single crystal 200.

[0193] As shown in Table 3, in samples 1 and 2, the dislocation density of the second end face 22 is 300 cm⁻¹. -2 In samples 3 to 13, the dislocation density at the second end face 22 is 80 cm⁻¹. -2 the following.

[0194] In samples 1 and 2, the dislocation density at the first end face 21 is 100 cm⁻¹. -2 In samples 6 to 8 and 10 to 13, the dislocation density at the first end face 21 is 60 cm⁻¹. -2 In samples 3 to 5 and 9, the dislocation density at the first end face 21 could not be determined.

[0195] In samples 5 to 13, the second value A of the second end face 22 is greater than 167% and less than 267%. In samples 6 to 8 and 10 to 13, the second value A of the first end face 21 is greater than 100% and less than 267%.

[0196] In samples 5 to 13, the second value B of the second end face 22 is 100% or more and 133% or less. In samples 6 to 13, the second value B of the second end face 22 is 100% or more and 114% or less. In samples 6 to 8 and 10 to 13, the second value B of the first end face 21 is 86% or more and 120% or less.

[0197] As confirmed above, compared with the manufacturing method of the InP single crystal 200 in the comparative example, the manufacturing method of the InP single crystal 200 according to the embodiment can reduce the deviation of dopant concentration and the dislocation density of the second end face 22.

[0198] It was further confirmed that 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), the generation of twins can be suppressed, and the deviation of dopant concentration, the dislocation density of the first end face 21 and the dislocation density of the second end face 22 can be reduced.

[0199] It should be considered that the embodiments and examples disclosed herein are exemplary in all respects and not limiting. The scope of the invention is defined not by the foregoing description but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.

[0200] Explanation of reference numerals in the attached figures

[0201] 1: First main surface; 2: Second main surface; 3: Outer peripheral surface; 5: Square area; 8: First outer edge; 10: First central rectangular area; 11: First outer rectangular area; 12: Second outer rectangular area; 13: Third outer rectangular area; 14: Fourth outer rectangular area; 15: Fifth outer rectangular area; 16: Sixth outer rectangular area; 17: Central square area; 18: Outer peripheral area; 19: Central area; 20: Second central rectangular area; 21: First end face; 22: Second End face; 23: Cylindrical surface; 25: Seventh outer rectangular region; 26: Eighth outer rectangular region; 28: Second outer edge; 29: Third outer edge; 30: Third central rectangular region; 35: Ninth outer rectangular region; 36: Tenth outer rectangular region; 40: Crucible; 41: Seed crystal receiving part; 41a: Bottom; 41b: Outer periphery; 42: Diameter expansion part; 43: Straight cylindrical part; 48: Heating element; 48a: First heating element part; 48b: Second heating element part; 48c: Third heating element part; 50: Inner cylinder 51: Lower end; 52: Upper end; 53: Side; 55: First axis; 56: Second axis; 57: Receiving part; 58: Filling component; 60: Crucible support; 84: Seed crystal; 85: Indium phosphide raw material; 86: Sealing material; 87: Molten indium phosphide; 88: Liquid sealing material; 91: First imaginary straight line; 92: Second imaginary straight line; 93: Third imaginary straight line; 94: Fourth imaginary straight line; 95: Fifth imaginary straight line; 96: Sixth imaginary straight 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. An indium phosphide single-crystal substrate having a main surface, The indium phosphide single crystal substrate contains dopants. 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⁻¹. -2 the following, When the concentration of the dopant at the center of the main surface is set as a first concentration and the concentration of the dopant at the outer edge of the main surface is set as a second concentration, the absolute value of the first concentration minus the second concentration divided by the first concentration is less than 10%.

2. The indium phosphide single crystal substrate according to claim 1, wherein, The main surface includes a central square area and a first outer rectangular area, a second outer rectangular area, a third outer rectangular area, and a fourth outer rectangular area. The central square region includes the center of the main surface and has a side length of 40mm. The first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region are located relative to the central square region in the [011] direction, the [0-1-1] direction, the [01-1] direction, and the [0-11] direction, respectively. The length of the short side of each of the first, second, third, and fourth outer rectangular regions is 20 mm. The length of the longest side of each of the first, second, third, and fourth outer rectangular regions is 40 mm. With the distance between the outer periphery of each of the first, second, third, and fourth outer periphery rectangular regions and the center of the main surface set as a first value, the radius of the main surface set as a second value, and the units of the first and second values ​​set as mm, the following conditions are met. The first value is obtained by multiplying the integer value obtained by dividing the second value by 10, discarding the decimal point, by 10. When the dislocation density of the central square region is set as the first density, and the average value of the dislocation densities of the first, second, third, and fourth outer rectangular regions is set as the second density,... The value obtained by dividing the second density by the first density is less than 267%. When the average dislocation density of the first outer rectangular region and the dislocation density of the second outer rectangular region are set as the third density, and the average dislocation density of the third outer rectangular region and the dislocation density of the fourth outer rectangular region are set as the fourth density,... The value obtained by dividing the fourth density by the third density is greater than 85% and less than 120%.

3. The indium phosphide single crystal substrate according to claim 1 or claim 2, wherein, The dislocation density on the main surface is 50 cm⁻¹. -2 the following.

4. The indium phosphide single crystal substrate according to any one of claims 1 to 3, wherein, The absolute value of the first concentration minus the second concentration divided by the first concentration is less than 5%.

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 the {100} surface.

9. The indium phosphide single crystal substrate according to claim 1, wherein, The main surface includes a central square area and a first outer rectangular area, a second outer rectangular area, a third outer rectangular area, and a fourth outer rectangular area. The central square region includes the center of the main surface and has a side length of 40mm. The first outer rectangular region, the second outer rectangular region, the third outer rectangular region, and the fourth outer rectangular region are located relative to the central square region in the [011] direction, the [0-1-1] direction, the [01-1] direction, and the [0-11] direction, respectively. The length of the short side of each of the first, second, third, and fourth outer rectangular regions is 20 mm. The length of the longest side of each of the first, second, third, and fourth outer rectangular regions is 40 mm. With the distance between the outer periphery of each of the first, second, third, and fourth outer periphery rectangular regions and the center of the main surface set as a first value, the radius of the main surface set as a second value, and the units of the first and second values ​​set as mm, the following conditions are met. The first value is obtained by multiplying the integer value obtained by dividing the second value by 10, discarding the decimal point, by 10. When the dislocation density of the central square region is set as the first density, and the average value of the dislocation densities of the first, second, third, and fourth outer rectangular regions is set as the second density,... The value obtained by dividing the second density by the first density is less than 267%. When the average dislocation density of the first outer rectangular region and the dislocation density of the second outer rectangular region are set as the third density, and the average dislocation density of the third outer rectangular region and the dislocation density of the fourth outer rectangular region are set as the fourth density,... The value obtained by dividing the fourth density by the third density is greater than 85% and less than 120%. The dislocation density on the main surface is 50 cm⁻¹. -2 the following, The absolute value of the first concentration minus the second concentration divided by the first concentration is less than 5%.

10. An indium phosphide single crystal, having a first end face and a second end face opposite to the first end face, The indium phosphide single crystal contains dopants. 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 of the first end face and the dislocation density of the second end face is 100 cm⁻¹. -2 the following, When the concentration of the dopant at the center of the first end face is set to a third concentration, the concentration of the dopant at the outer edge of the first end face is set to a fourth concentration, the concentration of the dopant at the center of the second end face is set to a fifth concentration, and the concentration of the dopant at the outer edge of the second end face is set to a sixth concentration, The absolute value of the third concentration minus the fourth concentration, divided by the third concentration, is less than 10%. The absolute value of the fifth concentration minus the sixth concentration, divided by the fifth concentration, is less than 10%.

11. A method for manufacturing indium phosphide single crystal, comprising: The process of placing seed crystals inside the crucible; The process of preparing indium phosphide raw material on the seed crystal; The process of preparing indium phosphide melt by melting a portion of the seed crystal and the indium phosphide raw material; The process of inserting the inner cylinder into the molten indium phosphide inside the crucible; as well as The process of solidifying the indium phosphide molten liquid by rotating the crucible relative to the inner cylinder while simultaneously moving the crucible, thereby causing the crucible to rotate relative to the inner cylinder. The crucible includes: A seed crystal receiving portion configured with the seed crystal; The diameter-expanding portion connected to the seed crystal receiving portion; and A straight cylindrical portion is disposed on the side opposite to the expanded diameter portion and the seed crystal receiving portion, and is connected to the expanded diameter portion. The difference between the diameter of the lower end of the inner cylinder and the inner diameter of the straight cylinder is more than 10 mm and less than 110 mm.

12. The method for manufacturing indium phosphide single crystals 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 cylinder is less than 55 mm.

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

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

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

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

17. The method for manufacturing indium phosphide single crystals according to claim 16, wherein, The inner cylinder includes a receiving portion and a filling member that fills the interior of the receiving portion. The filling component is made of indium phosphide.

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