Indium phosphide substrate and method for manufacturing the same

Abstract

The present invention provides an indium phosphide substrate having good linearity accuracy of a ridgeline where a main surface meets an orientation plane and a method for manufacturing the indium phosphide substrate. An indium phosphide substrate, characterized in that the indium phosphide substrate has a main surface and an orientation plane, and on the ridgeline where the main surface meets the orientation plane, except for a length portion of 3 mm inward from both ends of the ridgeline, a plurality of measurement points from a start point to an end point are set at intervals of 2 mm on the ridgeline, a straight line connecting the start point and the end point is set as a reference line, and the distance of each measurement point from the reference line is set as a deviation of each measurement point, and the maximum value of the deviation is less than 1 / 1000 of the length of the ridgeline.

Description

Technical Field

[0001] The invention relates to an indium phosphide substrate and a method for manufacturing the indium phosphide substrate. Background Art

[0002] Indium phosphide (InP) is a III-V compound semiconductor material composed of indium (In) of group III and phosphorus (P) of group V. As a semiconductor material, it has the following characteristics: band gap 1.35eV, electron mobility ~5400cm 2 / V·s, and the electron mobility under high electric field becomes higher than other common semiconductor materials such as silicon and gallium arsenide. In addition, it has the following characteristics: the stable crystal structure at room temperature and pressure is a cubic zinc blende structure, and its lattice constant has a larger lattice constant than compound semiconductors such as gallium arsenide (GaAs) and gallium phosphide (GaP).

[0003] An ingot of indium phosphide, which is a raw material of an indium phosphide substrate, is usually sliced ​​into a predetermined thickness, ground into a desired shape, and mechanically polished as appropriate, and then subjected to etching, precision polishing (polishing), etc., in order to remove grinding debris and damage caused by grinding.

[0004] In order to show the crystal orientation of the indium phosphide substrate, an orientation plane method is generally performed, for example, as disclosed in Patent Document 1, in which an arcuate portion of a predetermined area of ​​a circular substrate (wafer) is cut to expose a surface having a specific plane orientation. The short line segment indicating the orientation is called an orientation plane. In the wafer process, the orientation of the wafer is determined based on the orientation plane and various processes are performed.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-028723 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In the wafer process, the orientation plane serves as a reference for determining the orientation of the wafer, and its accuracy becomes important. In particular, for an indium phosphide substrate having a main surface and an orientation plane, when the indium phosphide substrate is observed from above the main surface using an optical microscope or the like and the orientation plane is used as a reference for determining the orientation of the wafer, the linearity of the ridgeline where the main surface and the orientation plane meet becomes very important.

[0010] However, in the orientation plane method of cutting off an arcuate portion of a specified area of ​​a circular substrate (wafer) of indium phosphide to expose a surface having a specific surface orientation, it is usually difficult to improve the accuracy of the linearity of the ridgeline connecting the main surface and the orientation plane, and it is desired to improve the technology related to improving the accuracy of the linearity of the ridgeline.

[0011] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an indium phosphide substrate having a high degree of linearity accuracy of an ridge line where a main surface contacts an orientation flat surface, and a method for producing an indium phosphide substrate.

[0012] Solutions for solving problems

[0013] In one embodiment, the present invention is an indium phosphide substrate, characterized in that the indium phosphide substrate has a main surface and an orientation plane, and on the ridge where the main surface meets the orientation plane, except for a length portion of 3 mm inward from both ends of the ridge, a plurality of measurement points are set on the ridge from a starting point to an end point at intervals of 2 mm, and a straight line connecting the starting point and the end point is set as a reference line. When the distance of each measurement point from the reference line is set as a deviation of each measurement point, the maximum value of the deviation is less than 1 / 1000 of the length of the ridge.

[0014] In one embodiment of the indium phosphide substrate of the present invention, the maximum value of the deviation is not more than 1 / 1500 of the length of the ridge line.

[0015] In another embodiment of the indium phosphide substrate of the present invention, the substrate thickness is 300 to 900 μm.

[0016] In still another embodiment of the indium phosphide substrate of the present invention, the length of the ridge line is 8% to 50% of the diameter of the main surface.

[0017] In another embodiment of the indium phosphide substrate of the present invention, the outer edge of the main surface is composed of the orientation flat surface and the arc portion connected to the orientation flat surface, and the maximum diameter of the main surface is greater than or equal to the length of the ridgeline and is 49 to 151 mm.

[0018] In another embodiment, the present invention is a method for manufacturing an indium phosphide substrate, which includes: a process of grinding an indium phosphide ingot using a grinding tool with a particle size number of #270 to #400 at a grinding tool conveying speed of 20 to 35 mm / minute to form an orientation plane; a process of cutting out a wafer having a main surface and an orientation plane from the ground ingot of indium phosphide; a process of chamfering the peripheral portion of the wafer other than the end face constituting the orientation plane; a process of grinding at least one surface of the chamfered wafer; and a process of etching the ground wafer under the following etching conditions.

[0019] Etching conditions

[0020] [Etching solution composition] When using 85 mass % phosphoric acid aqueous solution and 30 mass % hydrogen peroxide aqueous solution, the volume ratio is set as follows: the entire etching solution is 1, wherein the phosphoric acid aqueous solution: 0.2 to 0.4, the hydrogen peroxide aqueous solution: 0.1, and the remainder: water.

[0021] [Etching solution temperature] 60~100℃.

[0022] [Etching time] 8 to 15 minutes.

[0023] In another embodiment, the present invention is a method for manufacturing an indium phosphide substrate, which includes: a process of grinding an indium phosphide ingot to form an orientation plane; a process of cutting a wafer having a main surface and an orientation plane from the ground ingot of indium phosphide; for the wafer, using a grinding tool with a particle size number of #800 to #1200, grinding the end surface of the orientation plane at a grinding tool conveying speed of 60 to 180 mm / min, and chamfering the peripheral portion other than the orientation plane portion; a process of grinding at least one surface of the chamfered wafer; and a process of etching the ground wafer under the following etching conditions.

[0024] Etching conditions

[0025] [Etching solution composition] When using 85 mass % phosphoric acid aqueous solution and 30 mass % hydrogen peroxide aqueous solution, the volume ratio is set as follows: the entire etching solution is 1, wherein the phosphoric acid aqueous solution: 0.2-0.4, the hydrogen peroxide aqueous solution: 0.1, and the remainder: water.

[0026] [Etching solution temperature] 60~100℃.

[0027] [Etching time] 8 to 15 minutes.

[0028] Effects of the Invention

[0029] According to the embodiment of the present invention, it is possible to provide an indium phosphide substrate having a high degree of linearity accuracy of an ridge line where a main surface contacts an orientation flat surface, and a method for manufacturing an indium phosphide substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the appearance of an indium phosphide substrate according to an embodiment of the present invention.

[0031] Figure 2 This is a diagram for explaining an example of a method for measuring an edge line when the length of the edge line of the indium phosphide substrate according to the embodiment of the present invention is 24 mm.

[0032] Figure 3This is a diagram for explaining an example of a method for measuring an edge line when the length of the edge line of the indium phosphide substrate according to the embodiment of the present invention is 23 mm.

[0033] Figure 4 The diagram schematically shows the steps of the first method and the second method for producing an indium phosphide substrate according to an embodiment of the present invention and an ingot or a wafer produced by the steps. DETAILED DESCRIPTION

[0034] 〔Indium Phosphide Substrate〕

[0035] First, the structure of the indium phosphide substrate of this embodiment will be described.

[0036] The indium phosphide substrate 10 of this embodiment is as follows Figure 1 As shown in FIG. 1 , the main surface 11 and the orientation flat surface 12 are provided. In addition, a line connecting the main surface 11 and the orientation flat surface 12 is defined as an edge line 13 .

[0037] Here, the "principal surface" refers to the surface on which epitaxial growth is performed to form a semiconductor element structure. In addition, the "orientation plane" refers to the portion that appears after a portion of the periphery of the crystal is cut off, such as an arc, and corresponds to a straight line portion formed on a portion of the periphery when the principal surface of the substrate is viewed from above. The orientation plane mainly plays the role of displaying the crystal orientation of the substrate. The orientation plane is formed in a direction that is approximately perpendicular to the principal surface of the substrate when observed visually.

[0038] The plane orientation of the main surface 11 of the indium phosphide substrate 10 and the plane orientation of the orientation plane 12 in the embodiment of the present invention may be, for example, that the main surface 11 is a plane inclined in the range of 0° or more and 5° or less from the (100) plane to the <110> direction or the <111> direction close to the (100) plane, and the plane orientation of the orientation plane 12 is an equivalent plane consisting of the (0-1-1) plane, the (0-11) plane, the (011) plane, and the (01-1) plane. Strictly speaking, for example, the orientation plane of a wafer having a main surface inclined at 5° from the (100) plane to the

[111] direction is a plane inclined at 5° from the (0-1-1). In addition, in addition to the (011) plane, for example, the embodiment of the present invention can also be applied to the case where the orientation plane is added in a direction rotated by 45°. As described above, there is no particular limitation as long as it is a specific plane substantially perpendicular to the main surface 11 of the indium phosphide substrate 10. In addition, an embodiment of the present invention relates to an invention related to the manufacturing technology of the orientation plane of the indium phosphide substrate, but is not limited to the manufacturing technology of the orientation plane of the circular indium phosphide substrate. It is also effective in improving the linearity of the ridge part of the orientation plane attached to the rectangular substrate and can also be applied to the rectangular substrate.

[0039] The orientation plane 12 of the indium phosphide substrate 10 can also be formed by a portion of the outer periphery of the circular substrate of indium phosphide cut off in an arc shape. In this case, the outer edge of the main surface 11 is composed of the orientation plane 12 and the arc portion connected to the orientation plane 12. In addition, at this time, the maximum diameter of the main surface 11 can be 49 to 151 mm, or 49 to 101 mm. The maximum diameter of the main surface 11 is greater than the length of the ridge line. It should be noted that the indium phosphide substrate 10 can also be a quadrilateral such as a rectangle.

[0040] The length of the ridgeline 13 where the main surface 11 meets the orientation flat surface 12 is not particularly limited as long as it is a length that can fully ensure the area of ​​the main surface 11, and is preferably 8% to 50% of the diameter of the wafer (the diameter of the main surface 11). If the length of the ridgeline 13 where the main surface 11 meets the orientation flat surface 12 is less than 8% of the wafer diameter (the diameter of the main surface 11), it may become difficult to confirm the existence of the orientation flat (OF: Orientation Flat). If the length of the ridgeline 13 where the main surface 11 meets the orientation flat surface 12 exceeds 50% of the wafer diameter (the diameter of the main surface 11), there may be a problem of a reduction in the effective area of ​​the wafer. The length of the ridgeline 13 where the main surface 11 meets the orientation flat surface 12 is more preferably 10% to 40% of the wafer diameter (the diameter of the main surface 11), and more preferably 20% to 40%.

[0041] The thickness of the indium phosphide substrate 10 is not particularly limited, and is preferably 300 to 900 μm, more preferably 300 to 700 μm. In particular, in the case of a large aperture, if the thickness of the indium phosphide substrate 10 is less than 300 μm, it may break, and if the thickness of the indium phosphide substrate 10 exceeds 900 μm, the problem of waste of the parent material crystal may occur.

[0042] The indium phosphide substrate 10 is controlled as follows: except for the length portion 3 mm inward from both ends of the edge 13, multiple measurement points are set from the starting point to the end point at intervals of 2 mm on the edge 13, and the straight line connecting the starting point and the end point is set as the reference line. When the distance of each measurement point from the reference line is set as the deviation of each measurement point, the maximum value of the deviation is less than 1 / 1000 of the length of the edge 13.

[0043] The maximum value of the deviation will be described in more detail using the drawings. Figure 2 The length of the ridge 13 of the indium phosphide substrate is 24 mm. First, a total of 10 measurement points are set from the start point to the end point at intervals of 2 mm in a total length of 18 mm, excluding the length of 3 mm inward from both ends of the ridge 13. Figure 2In the example, each measurement point is represented by a black dot. Next, the straight line connecting the start point and the end point is set as the baseline, and the distance of each measurement point from the baseline is set as the deviation of each measurement point. Next, the deviation of a total of 8 measurement points excluding the start point and the end point is evaluated, and the largest value is set as the maximum deviation. Figure 2 The deviation of the fourth measurement point from the starting point is the largest. Figure 2 These are created for explanation purposes only and do not accurately represent the relationship (ratio, etc.) between actual edge lines and the magnitude of deviations.

[0044] also, Figure 3 The length of the ridgeline 13 of the indium phosphide substrate is 23 mm. First, a total of 9 measurement points are set from the start point to the end point at intervals of 2 mm in a total length of 17 mm, excluding the length of 3 mm inward from both ends of the ridgeline 13. Figure 3 In the example, each measurement point is represented by a black dot. Next, the straight line connecting the start point and the end point is set as the baseline, and the distance of each measurement point from the baseline is set as the deviation of each measurement point. Next, the deviation of a total of 7 measurement points excluding the start point and the end point is evaluated, and the largest value is set as the maximum deviation. Figure 3 The deviation of the fourth measurement point from the starting point is the largest. Figure 3 It is produced for the purpose of explanation and does not accurately represent the relationship (ratio, etc.) between the actual edge line and the size of the deviation. Figure 3 In the example of , the measurement points are set at intervals of 2 mm from the starting point. As a result, the point (end point) set at intervals of 2 mm at the end does not coincide with the end of the length portion except for the length portion 3 mm inward from both ends of the ridge line. Figure 2 In the example, measurement points are set at intervals of 2 mm from the starting point, and as a result, the point (end point) set at the last interval of 2 mm coincides with the end of the length portion except for the length portion 3 mm inward from both ends of the ridge line.

[0045] That is, the setting method of the measuring point of the edge line 13 in the present invention is as follows: in addition to the point 3 mm inward from both ends of the edge line, the point 3 mm inward from one end is set as the starting point, and the measuring points from the starting point to the end point are set at intervals of 2 mm on the edge line. When the interval from the other end is less than 3 mm, no measuring point is set. By defining in this way, even when the length of the edge line 13 is an even value, an odd value, a value below a meaningful decimal point (for example, when the edge line length of the orientation plane is 22.2 mm), etc., the above-mentioned maximum deviation can be evaluated.

[0046] The indium phosphide substrate 10 is controlled so that the maximum value of the above-mentioned deviation is less than 1 / 1000 of the length of the ridge 13. According to such a configuration, when the indium phosphide substrate 10 is observed from above the main surface 11 using an optical microscope or the like, and the orientation plane 12 is used as a reference for determining the orientation of the wafer, the linearity accuracy of the ridge 13 where the main surface 11 and the orientation plane 12 meet becomes good, and the wafer can be accurately determined to be in the desired orientation.

[0047] The maximum value of the above-mentioned deviation is preferably 1 / 1500 or less, more preferably 1 / 2000 or less, and further preferably 1 / 2500 or less of the length of the ridge line 13 .

[0048] [Method for producing indium phosphide substrate]

[0049] Next, a method for manufacturing an indium phosphide substrate according to an embodiment of the present invention is described. The method for manufacturing an indium phosphide substrate according to an embodiment of the present invention includes a first manufacturing method and a second manufacturing method. Figure 4 Schematic diagrams showing the steps of the first manufacturing method and the second manufacturing method and the ingots or wafers produced through the steps.

[0050] (First Manufacturing Method)

[0051] As a first method for producing an indium phosphide substrate, first, an ingot of indium phosphide is prepared by a known method.

[0052] Next, the ingot of indium phosphide was ground into a cylinder using a grinder (grindstone) with a grain size of #270 to #400 at a grinder feed rate of 20 to 35 mm / min, and an orientation flat (OF) was formed.

[0053] In the technical field to which the present invention belongs, the number used as the above-mentioned "grain size number #" corresponds to the grain size of the abrasive tool. The larger the number of the grain size number #, the smaller the grain size of the abrasive tool, and the smaller the number of the grain size number, the larger the grain size of the abrasive tool.

[0054] Furthermore, the “grinding wheel conveyance speed” indicates the speed of relative movement of the grinding wheel rotation axis with respect to the ingot in a state where the rotating grinding wheel is pressed against the ingot of indium phosphide for grinding.

[0055] Next, wafers having a principal surface and an orientation flat surface are cut out from the ground ingot of indium phosphide. At this time, both ends of the crystal of the ingot of indium phosphide are cut along a predetermined crystal plane using a wire saw or the like, and a plurality of wafers having a predetermined thickness are cut out.

[0056] Next, the peripheral portion of the wafer other than the end face constituting the orientation flat surface is chamfered. Figure 4In the chamfering (wafer grinding) step of the first manufacturing method, it is shown as “grinding amount”.

[0057] Next, at least one surface of the chamfered wafer, preferably both surfaces, is ground. This grinding process is also called a lapping process, and the unevenness on the wafer surface is removed by grinding with a predetermined abrasive.

[0058] Next, the polished wafer was etched under the following etching conditions.

[0059] Etching conditions

[0060] [Etching solution composition] When using 85 mass % phosphoric acid aqueous solution and 30 mass % hydrogen peroxide aqueous solution, the volume ratio is set as follows: the entire etching solution is 1, wherein the phosphoric acid aqueous solution: 0.2-0.4, the hydrogen peroxide aqueous solution: 0.1, and the remainder: water.

[0061] [Etching solution temperature] 60~100℃.

[0062] [Etching time] 8 to 15 minutes.

[0063] The wafer is etched by immersing the entire wafer in the etching solution.

[0064] Next, the main surface of the wafer is polished with a mirror polishing abrasive to be finished into a mirror surface.

[0065] Next, cleaning is performed to manufacture the indium phosphide substrate according to the embodiment of the present invention.

[0066] In the first method for manufacturing an indium phosphide substrate, the linearity of the ridgeline portion of the orientation flat is controlled by optimizing the conditions for forming the orientation flat in the ingot of indium phosphide and the etching conditions for the polished wafer.

[0067] (Second Manufacturing Method)

[0068] As a second method for producing an indium phosphide substrate, first, an ingot of indium phosphide is prepared by a known method.

[0069] Next, the ingot of indium phosphide was ground into a cylinder, and an orientation flat (OF) was formed.

[0070] Next, wafers having a principal surface and an orientation flat surface are cut out from the ground ingot of indium phosphide. At this time, both ends of the crystal of the ingot of indium phosphide are cut along a predetermined crystal plane using a wire saw or the like, and a plurality of wafers having a predetermined thickness are cut out.

[0071] Next, the end face of the orientation plane is ground using a grinding tool with a grit number of #800 to #1200 at a grinding tool feed speed of 60 to 180 mm / min. The "grinding tool feed speed" refers to the speed at which the contact portion of the wafer periphery and the grinding tool moves relative to the wafer periphery when the rotating grinding tool is pushed against the wafer periphery for grinding. The peripheral grinding portion in this process is Figure 4 The chamfering (wafer grinding) step of the second manufacturing method is the part indicated as the "grinding amount", but the chamfering is not performed on the orientation flat portion, and only the end surface is ground. The chamfering process is performed on the peripheral portion other than the orientation flat portion.

[0072] Next, at least one surface of the chamfered wafer, preferably both surfaces, is ground. This grinding process is also called a lapping process, and the unevenness on the wafer surface is removed by grinding with a predetermined abrasive.

[0073] Next, the polished wafer was etched under the following etching conditions.

[0074] Etching conditions

[0075] [Etching solution composition] When using 85 mass % phosphoric acid aqueous solution and 30 mass % hydrogen peroxide aqueous solution, the volume ratio is set as follows: the entire etching solution is 1, wherein the phosphoric acid aqueous solution: 0.2-0.4, the hydrogen peroxide aqueous solution: 0.1, and the remainder: water.

[0076] [Etching solution temperature] 60~100℃.

[0077] [Etching time] 8 to 15 minutes.

[0078] The wafer is etched by immersing the entire wafer in the etching solution.

[0079] Next, the main surface of the wafer is polished with a mirror polishing abrasive to be finished into a mirror surface.

[0080] Next, cleaning is performed to manufacture the indium phosphide substrate according to the embodiment of the present invention.

[0081] In the second method for manufacturing an indium phosphide substrate, the linearity of the ridgeline portion of the orientation flat is controlled by optimizing the grinding conditions of the end surface of the orientation flat of the wafer and the etching conditions of the ground wafer.

[0082] It should be noted that, when the grinding conditions of the end face of the orientation plane of the wafer in the second method for manufacturing the indium phosphide substrate are set to be the same as the ingot grinding conditions in the first method for manufacturing the indium phosphide substrate described above, or when only fine grinding is performed, it is difficult to control the linearity of the ridge line as well as the indium phosphide substrate of the embodiment of the present invention. This is because the grinding methods are different in ingot grinding and wafer grinding, and in wafer grinding, in particular, the wafer may vibrate during grinding.

[0083] By epitaxially growing a semiconductor thin film on an indium phosphide substrate of an embodiment of the present invention using a known method, a semiconductor epitaxial wafer can be produced. As an example of this epitaxial growth, a HEMT (High Electron Mobility Transistor) structure can be formed by epitaxially growing an InAlAs buffer layer, an InGaAs channel layer, an InAlAs spacer layer, and an InP electron supply layer on an indium phosphide substrate. In the case of producing a semiconductor epitaxial wafer having such a HEMT structure, the indium phosphide substrate after mirror finishing is usually subjected to an etching treatment using an etching solution such as sulfuric acid / hydrogen peroxide water to remove impurities such as silicon (Si) attached to the surface of the substrate. Usually, the amount of etching removed here is small and does not change the ridgeline of the oriented plane portion. Then, an epitaxial film is formed on the indium phosphide substrate after the etching treatment using a molecular beam epitaxy method (MBE: Molecular Beam Epitaxy) or an organic metal vapor deposition method (MOCVD: Metal Organic Chemical Vapor Deposition).

[0084] Example

[0085] Hereinafter, examples are provided for better understanding of the present invention and its advantages, but the present invention is not limited to these examples.

[0086] Test Example 1

[0087] Based on the production flow of the above-mentioned first production method, Examples 1 to 4 and Comparative Examples 1 to 4 were produced as described below.

[0088] First, an ingot of an indium phosphide single crystal grown to have a diameter of φ80 mm or more was prepared.

[0089] Next, the outer circumference of the ingot of the indium phosphide single crystal was ground to form a cylinder and an orientation flat (OF). For the outer circumference grinding of the ingot, the grinding tool had the grain size and metal bond shown in Table 1 and the grinding tool conveying speed shown in Table 1 was used.

[0090] Next, wafers having a principal surface and an orientation flat surface were cut out from the ground ingot of indium phosphide. At this time, both ends of the crystal of the ingot of indium phosphide were cut along a predetermined crystal plane using a wire saw to cut out a plurality of wafers with a predetermined thickness.

[0091] Next, in the wafer, the outer peripheral portion other than the end surface constituting the orientation flat is chamfered.

[0092] Next, both surfaces of the chamfered wafer are polished with an abrasive to remove the irregularities on the wafer surface.

[0093] Next, the wafer was immersed in an etching solution and etched at a predetermined temperature for a predetermined time. The etching conditions are shown in Table 1. It should be noted that the "phosphoric acid aqueous solution" shown in Table 1 used an 85 mass % phosphoric acid aqueous solution, the "hydrogen peroxide aqueous solution" used a 30 mass % hydrogen peroxide aqueous solution, and the "sulfuric acid" used a 96 mass % sulfuric acid.

[0094] Next, the main surface of the wafer was polished to a mirror finish using a mirror polishing abrasive and then cleaned to produce an indium phosphide substrate having a diameter of 76.2 mm and a thickness of 600 to 625 μm. The ridgeline of the orientation flat of the indium phosphide substrate was formed to be 22 mm in length.

[0095] Test Example 2

[0096] As Example 5, an indium phosphide substrate was produced in the same manner as in Examples 1 to 4 except for the following points (1) and (2).

[0097] (1) An ingot of an indium phosphide single crystal grown to a diameter of 104 mm or more was prepared.

[0098] (2) The main surface of the wafer was polished to a mirror finish using a mirror polishing abrasive and then cleaned to produce an indium phosphide substrate having a diameter of 100 mm and a thickness of 600 to 625 μm. The ridgeline of the orientation flat of the indium phosphide substrate was formed to be 32.5 mm in length.

[0099] Test Example 3

[0100] Based on the production flow of the second production method described above, Examples 6 to 9 and Comparative Examples 5 to 8 were produced as described below.

[0101] First, an ingot of an indium phosphide single crystal grown to have a diameter of φ80 mm or more was prepared.

[0102] Next, the outer circumference of the ingot of the indium phosphide single crystal was ground to form a cylinder and an orientation flat (OF). For the outer circumference grinding of the ingot, the grinding tool had the grain size and metal bond shown in Table 2 and the grinding tool conveying speed shown in Table 2 was used.

[0103] Next, wafers having a principal surface and an orientation flat surface were cut out from the ground ingot of indium phosphide. At this time, both ends of the crystal of the ingot of indium phosphide were cut along a predetermined crystal plane using a wire saw to cut out a plurality of wafers with a predetermined thickness.

[0104] Next, the end surface of the orientation flat surface of the wafer was ground. The grinding tool used in this grinding had the grit number shown in Table 2 and the grinding tool feed speed shown in Table 2. The outer peripheral portion other than the orientation flat surface portion was chamfered.

[0105] Next, both surfaces of the chamfered wafer are polished with an abrasive to remove the irregularities on the wafer surface.

[0106] Next, the wafer was immersed in an etching solution and etched at a predetermined temperature for a predetermined time. The etching conditions are shown in Table 2. It should be noted that the "phosphoric acid aqueous solution" shown in Table 2 used an 85 mass % phosphoric acid aqueous solution, the "hydrogen peroxide aqueous solution" used a 30 mass % hydrogen peroxide aqueous solution, and the "sulfuric acid" used a 96 mass % sulfuric acid.

[0107] Next, the main surface of the wafer was polished to a mirror finish using a mirror polishing abrasive and then cleaned to produce an indium phosphide substrate having a diameter of 76.2 mm and a thickness of 600 to 625 μm. The ridgeline of the orientation flat of the indium phosphide substrate was formed to be 22 mm in length.

[0108] Test Example 4

[0109] As Example 10, an indium phosphide substrate was produced in the same manner as in Examples 6 to 9 except for the following points (1) and (2).

[0110] (1) An ingot of an indium phosphide single crystal grown to a diameter of 104 mm or more was prepared.

[0111] (2) The main surface of the wafer was polished to a mirror finish using a mirror polishing abrasive and then cleaned to produce an indium phosphide substrate having a diameter of 100 mm and a thickness of 600 to 625 μm. The ridgeline of the orientation flat of the indium phosphide substrate was formed to be 32.5 mm in length.

[0112] (Evaluation 1)

[0113] For the indium phosphide substrates of Examples 1 to 4, Examples 6 to 9, and Comparative Examples 1 to 8, a total of 9 measurement points were set from the start point to the end point at intervals of 2 mm in a total length of 16 mm, excluding a length portion of 3 mm inward from both ends of the ridge. Next, a straight line connecting the start point and the end point was set as a reference line, and the distance of each measurement point from the reference line was set as the deviation of each measurement point. Next, the deviation of the total of 7 measurement points excluding the start point and the end point was evaluated, and the largest value was set as the maximum deviation. In addition, the ratio of the maximum deviation to the ridge length was calculated.

[0114] (Rating 2)

[0115] Regarding the indium phosphide substrates of Examples 5 and 10, a total of 14 measurement points were set at intervals of 2 mm from the start point to the end point in a total length of 26.5 mm, excluding a length portion of 3 mm inward from both ends of the ridge. Next, a straight line connecting the start point and the end point was set as a reference line, and the distance of each measurement point from the reference line was set as the deviation of each measurement point. Next, the deviation of the total of 12 measurement points excluding the start point and the end point was evaluated, and the largest value was set as the maximum deviation. In addition, the ratio of the maximum deviation to the ridge length was calculated.

[0116] Tables 1 and 2 show the above-mentioned production conditions and the results of Evaluation 1 and Evaluation 2.

[0117] [Table 1]

[0118]

[0119] [Table 2]

[0120]

[0121] (Evaluation results)

[0122] In Examples 1 to 10, the maximum value of the deviation was 1 / 1000 or less of the length of the ridge line, and an indium phosphide substrate having good linearity accuracy of the ridge line where the main surface and the orientation flat were in contact was obtained.

[0123] In Comparative Examples 1, 4, 5, and 8, the composition of the liquid used for etching was inappropriate in the ridge formation conditions, and the maximum value of the deviation exceeded 1 / 1000 of the length of the ridge.

[0124] In Comparative Example 2, the grain size of the grinding wheel used for the ingot outer periphery grinding was inappropriate in the ridge forming conditions, and the maximum value of the deviation exceeded 1 / 1000 of the length of the ridge.

[0125] In Comparative Example 3, among the ridge forming conditions, the grinding wheel feeding speed set during the ingot outer periphery grinding was inappropriate, and the maximum value of the deviation exceeded 1 / 1000 of the length of the ridge.

[0126] In Comparative Example 6, the grain size of the grinding wheel used for wafer outer periphery grinding was inappropriate in the ridge line formation conditions, and the maximum value of the deviation exceeded 1 / 1000 of the ridge line length.

[0127] In Comparative Example 7, among the ridge line formation conditions, the grinding wheel conveyance speed set in the wafer outer periphery grinding was inappropriate, and the maximum value of the deviation exceeded 1 / 1000 of the length of the ridge line.

[0128] Description of Reference Numerals

[0129] 10: InP substrate; 11: main surface; 12: orientation plane; 13: ridge line.

Claims

1. A method for manufacturing an indium phosphide substrate, comprising: A process of grinding an indium phosphide ingot using a grinding tool with a particle size of #270 to #400 at a grinding tool conveying speed of 20 to 35 mm / min to form an oriented plane; A step of cutting out a wafer having a main surface and an orientation flat surface from the ground ingot of indium phosphide; A step of chamfering the outer peripheral portion of the wafer other than the end surface constituting the orientation flat surface; A step of grinding at least one surface of the chamfered wafer; as well as The step of etching the polished wafer under the following etching conditions: Etching conditions Etching liquid composition: When using 85 mass % phosphoric acid aqueous solution and 30 mass % hydrogen peroxide aqueous solution, the volume ratio is set as follows: the entire etching liquid is 1, wherein the phosphoric acid aqueous solution: 0.2-0.4, the hydrogen peroxide aqueous solution: 0.1, and the remainder: water, Etching solution temperature: 60~100℃, Etching time: 8 to 15 minutes.

2. A method for manufacturing an indium phosphide substrate, comprising: A process of grinding an indium phosphide ingot to form an oriented flat surface; A step of cutting out a wafer having a main surface and an orientation flat surface from the ground ingot of indium phosphide; The wafer is ground using a grinding tool with a grain size of #800 to #1200 at a grinding tool conveying speed of 60 to 180 mm / min to grind the end surface of the orientation flat surface, and chamfering the outer peripheral portion other than the orientation flat surface portion; A step of grinding at least one surface of the chamfered wafer; as well as The step of etching the polished wafer under the following etching conditions: Etching conditions Etching liquid composition: When using 85 mass % phosphoric acid aqueous solution and 30 mass % hydrogen peroxide aqueous solution, the volume ratio is set as follows: the entire etching liquid is 1, wherein the phosphoric acid aqueous solution: 0.2-0.4, the hydrogen peroxide aqueous solution: 0.1, and the remainder: water, Etching solution temperature: 60~100℃, Etching time: 8 to 15 minutes.

3. An indium phosphide substrate manufactured by the method for manufacturing an indium phosphide substrate according to claim 1 or 2, wherein the indium phosphide substrate has a main surface and an orientation plane, On the ridge where the main surface meets the orientation plane, except for a length portion of 3 mm inward from both ends of the ridge, a plurality of measurement points are set on the ridge from the starting point to the end point at intervals of 2 mm, and a straight line connecting the starting point and the end point is set as a reference line, and the distance of each measurement point from the reference line is set as a deviation of each measurement point, and the maximum value of the deviation is greater than 0.27 of 1000 and less than 1 of 1000 of the length of the ridge.

4. The indium phosphide substrate according to claim 3, wherein: The maximum value of the deviation is greater than or equal to 0.27 / 1000 and less than or equal to 1 / 1500 of the length of the ridge line.

5. The indium phosphide substrate according to claim 3 or 4, wherein The substrate thickness is 300 to 900 μm.

6. The indium phosphide substrate according to claim 3 or 4, wherein The length of the ridge line is 8% to 50% of the diameter of the main surface.

7. The indium phosphide substrate according to claim 3 or 4, wherein The outer edge of the main surface is composed of the orientation flat surface and an arc portion connected to the orientation flat surface. The maximum diameter of the main surface is greater than or equal to the length of the ridge line and is 49 to 151 mm.

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