JP6906079B2 - Indium phosphide substrate - Google Patents

Description

The present invention relates to an indium phosphide substrate.

Indium phosphide (InP) is a group III-V compound semiconductor material composed of group III indium (In) and group V phosphorus (P). The characteristics of the semiconductor material are a band gap of 1.35 eV and electron mobility of ~ 5400 cm ² / V · s, and the electron mobility under a high electric field is higher than that of other general semiconductor materials such as silicon and gallium arsenide. It has the characteristic of becoming. The stable crystal structure under normal temperature and pressure is a cubic zinchalerite type structure, and its lattice constant is larger than that of compound semiconductors such as gallium arsenide (GaAs) and gallium phosphide (GaP). It has the characteristic of having a lattice constant.

Indium phosphide ingots, which are the raw material for indium phosphide substrates, are usually sliced to a predetermined thickness, ground to a desired shape, appropriately mechanically polished, and then removed from polishing debris and damage caused by polishing. Therefore, it is used for etching, precision polishing (polishing), and the like.

What is generally done to indicate the crystal orientation of an indium phosphide substrate is to cut out an arched portion of a predetermined region of a circular substrate (wafer) and have a specific plane orientation, for example, as disclosed in Patent Document 1. This is an orientation flat method that exposes the surface. A short line segment indicating the orientation is called an orientation flat. In the wafer process, the orientation of the wafer is determined based on the orientation flat, and various processes are performed.

Japanese Unexamined Patent Publication No. 2014-028723

In the wafer process, the orientation flat is a standard for determining the orientation of the wafer, and its accuracy is important. In particular, in an indium phosphide substrate having a main surface and an orientation flat, when the indium phosphide substrate is observed from above the main surface with an optical microscope or the like and the orientation flat is used as a reference for determining the orientation of the wafer, the main surface is used. The straightness of the ridgeline in contact with the orientation flat is very important.

However, in the orientation flat method in which the arcuate portion of a predetermined region of an indium phosphide circular substrate (wafer) is cut out to expose a surface having a specific surface orientation, the accuracy of the linearity of the ridge line where the main surface and the orientation flat contact is improved. It is generally difficult to improve, and it is desired to improve the technique for improving the accuracy of the linearity of the ridgeline.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an indium phosphide substrate having good linearity accuracy of a ridge line where a main surface and an orientation flat are in contact with each other.

In one embodiment, the present invention is a phosphorinated indium substrate having a main surface and an orientation flat, excluding a portion having a length of 3 mm inward from both ends of the ridge line at a ridge line where the main surface and the orientation flat are in contact with each other. Then, a plurality of measurement points from the start point to the end point are set at intervals of 2 mm on the ridge line, the straight line connecting the start point and the end point is used as a reference line, and the distance of each measurement point from the reference line is defined as the reference line. when the deviation of each measurement point, the maximum value of the deviation state, and are less than one thousandth of the length of the ridge, the largest diameter of the main surface is 49～151Mm, the length of the ridge is indium phosphide substrate, wherein 8-50% der Rukoto diameter of said main surface.

In one embodiment of the indium phosphide substrate of the present invention, the maximum value of the deviation is 1/1500 or less of the length of the ridgeline.

In another embodiment, the indium phosphide substrate of the present invention has a substrate thickness of 300 to 900 μm.

In yet another embodiment of the indium phosphide substrate of the present invention, the outer edge of the main surface is composed of the orientation flat and an arc portion connected to the orientation flat, and the maximum diameter of the main surface is the length of the ridgeline. It is more than that and is 49 to 151 mm.

In another embodiment of the present invention, a step of grinding an ingot of indium phosphate with a wafer having a count of # 270 to # 400 at a polishing speed of 20 to 35 mm / min to form an orientation flat, and the above-mentioned step. A step of cutting out a wafer having a main surface and an orientation flat from a ground ingot of indium phosphate, a step of chamfering an outer peripheral portion of the wafer other than the end face constituting the orientation flat, and at least one of the chamfered wafers. A step of polishing the surface of the wafer and a step of etching the polished wafer under the following etching conditions.
Etching conditions [Etching liquid composition] When 85% by mass of phosphoric acid aqueous solution and 30% by mass of hydrogen peroxide solution are used, the phosphoric acid aqueous solution: 0.2 to 0.4 and the hydrogen peroxide solution: 0.1. , Remaining: Water, set the volume ratio so that the entire etching solution is 1. [Etching solution temperature] 60 to 100 ° C.
[Etching time] A method for producing an indium phosphide substrate, which comprises 8 to 15 minutes.

In yet another embodiment of the present invention, there is a step of grinding an ingot of indium phosphate to form an orientation flat, and a step of cutting out a wafer having a main surface and an orientation flat from the ground ingot of indium phosphate. In the wafer, the step of grinding the end face portion of the orientation flat portion with a grindstone having a count of # 800 to # 1200 at a grindstone feed rate of 60 to 180 mm / min and chamfering the outer peripheral portion other than the orientation flat portion, and the above. A step of polishing at least one surface of the chamfered wafer and a step of etching the polished wafer under the following etching conditions.
Etching conditions [Etching liquid composition] When 85% by mass of phosphoric acid aqueous solution and 30% by mass of hydrogen peroxide solution are used, the phosphoric acid aqueous solution: 0.2 to 0.4 and the hydrogen peroxide solution: 0.1. , Remaining: Water, set the volume ratio so that the entire etching solution is 1. [Etching solution temperature] 60 to 100 ° C.
[Etching time] A method for producing an indium phosphide substrate, which comprises 8 to 15 minutes.

According to the embodiment of the present invention, it is possible to provide an indium phosphide substrate having good linearity accuracy of the ridge line where the main surface and the orientation flat are in contact with each other.

It is a schematic appearance figure of the indium phosphide substrate which concerns on embodiment of this invention. It is a figure explaining an example of the measurement method of the ridge line when the length of the ridge line of the indium phosphide substrate which concerns on embodiment of this invention is 24 mm. It is a figure explaining an example of the measurement method of the ridge line when the length of the ridge line of the indium phosphide substrate which concerns on embodiment of this invention is 23 mm. It is a schematic diagram of each step of the 1st manufacturing method and 2nd manufacturing method of the indium phosphide substrate which concerns on embodiment of this invention, and the ingot or the wafer manufactured in each step.

[Indium phosphide substrate]
First, the configuration of the indium phosphide substrate of the present embodiment will be described.
As shown in FIG. 1, the indium phosphide substrate 10 of the present embodiment has a main surface 11 and an orientation flat 12. Further, the line formed by the contact between the main surface 11 and the orientation flat 12 is defined as the ridge line 13.

Here, the "main surface" is a surface on which epitaxial growth is performed in order to form a semiconductor device structure. Further, the "orientation flat" is a part that appears after cutting a part of the outer circumference of the crystal into a bow shape, for example, and corresponds to a straight part formed on a part of the outer circumference when the main surface of the substrate is viewed from above. do. The orientation flat mainly serves to indicate the crystal orientation of the substrate. The orientation flat is formed in a direction substantially perpendicular to the main surface of the substrate when visually observed.

The plane orientation of the main surface 11 of the phosphorinated indium substrate 10 and the plane orientation of the orientation flat 12 in the embodiment of the present invention are, for example, the <110> direction or the <111> direction in which the main surface 11 is close to the (100) plane. It is a plane inclined in the range of 0 ° or more and 5 ° or less, and the plane orientation of the orientation flat 12 is (0-1-1) plane, (0-11) plane, (011) plane and (01-1) plane. It may be an equivalent surface consisting of. Strictly speaking, for example, the orientation flat of a wafer having a main surface inclined by 5 ° in the [111] direction from the (100) plane is a plane inclined by 5 ° from (0-1-1), and other than the (011) plane. The embodiment of the present invention can also be applied to, for example, when an orientation flat is provided in a direction rotated by 45 °, as long as it is a specific surface substantially perpendicular to the main surface 11 of the indium phosphide substrate 10 as described above. , There is no particular limitation. Further, although the embodiment of the present invention relates to an invention relating to an orientation flat manufacturing technique for a phosphorinated indium substrate, the present invention is not limited to the manufacturing technique for an orientation flat for a circular indium phosphate substrate, and is attached to a rectangular substrate. It is also effective in improving the linearity of the ridgeline of the orientation flat, and can be applied to rectangular substrates.

The orientation flat 12 of the indium phosphide substrate 10 may be formed by a portion that appears after a part of the outer circumference of the circular substrate of the indium phosphide is cut out in a bow shape. In that case, the outer edge of the main surface 11 is composed of an orientation flat 12 and an arc portion connected to the orientation flat 12. At this time, the maximum diameter of the main surface 11 may be 49 to 151 mm or 49 to 101 mm. The maximum diameter of the main surface 11 is equal to or larger than the length of the ridgeline. The indium phosphide substrate 10 may be a rectangle such as a quadrangle.

The length of the ridge line 13 in which the main surface 11 and the orientation flat 12 are in contact with each other is not particularly limited as long as the area of the main surface 11 can be sufficiently secured, but is the diameter of the wafer (diameter of the main surface 11). It is preferably 8 to 50%. If the length of the ridge line 13 in which the main surface 11 and the orientation flat 12 are in contact with each other is less than 8% of the wafer diameter (diameter of the main surface 11), it may be difficult to confirm the existence of the orientation flat (OF). If the length of the ridge line 13 in which the main surface 11 and the orientation flat 12 are in contact with each other exceeds 50% of the wafer diameter (diameter of the main surface 11), there is a possibility that the effective area of the wafer may be reduced. The length of the ridge line 13 in which the main surface 11 and the orientation flat 12 are in contact with each other is more preferably 10 to 40% of the diameter of the wafer (diameter of the main surface 11), and even more preferably 20 to 40%. ..

The thickness of the indium phosphide substrate 10 is not particularly limited, but is preferably 300 to 900 μm, more preferably 300 to 700 μm, for example. In particular, when the diameter is large, if the indium phosphide substrate 10 is less than 300 μm, it may crack, and if it exceeds 900 μm, the base metal crystal may be wasted.

In the phosphorinated indium substrate 10, a plurality of measurement points from the start point to the end point are set at intervals of 2 mm on the ridge line 13 except for a length portion of 3 mm inward from both ends of the ridge line 13, and the start point and the end point are connected. When the straight line is used as the reference line and the distance from the reference line of each measurement point is used as the deviation of each measurement point, the maximum value of the deviation is controlled to be 1/1000 or less of the length of the ridge line 13.

The maximum value of the deviation will be described more specifically with reference to the drawings. FIG. 2 shows a case where the length of the ridge line 13 of the indium phosphide substrate is 24 mm. First, a total of 10 measurement points from the start point to the end point are set at intervals of 2 mm in a total length portion of 18 mm excluding a length portion of 3 mm inward from both ends of the ridge line 13. In FIG. 2, each measurement point is indicated by a black circle. Next, the straight line connecting the start point and the end point is used as the reference line, and the distance of each measurement point from the reference line is used as the deviation of each measurement point. Next, the deviations at a total of eight measurement points excluding the start point and the end point are evaluated, and the maximum one is set as the maximum deviation. In FIG. 2, the deviation at the fourth measurement point counting from the start point is the maximum. Note that FIG. 2 is created for the purpose of explanation, and does not accurately show the size relationship (ratio, etc.) between the actual ridgeline and the deviation.

Further, FIG. 3 shows a case where the length of the ridge line 13 of the indium phosphide substrate is 23 mm. First, a total of nine measurement points from the start point to the end point are set at intervals of 2 mm in a total length portion of 17 mm excluding the length portion of 3 mm inward from both ends of the ridge line 13. In FIG. 3, each measurement point is indicated by a black circle. Next, the straight line connecting the start point and the end point is used as the reference line, and the distance of each measurement point from the reference line is used as the deviation of each measurement point. Next, the deviations at a total of seven measurement points excluding the start point and the end point are evaluated, and the maximum one is set as the maximum deviation. In FIG. 3, the deviation at the fourth measurement point counting from the start point is the maximum. Note that FIG. 3 is created for the purpose of explanation, and does not accurately show the size relationship (ratio, etc.) between the actual ridgeline and the deviation. In the example of FIG. 3, as a result of setting the measurement points at intervals of 2 mm from the start point, the points (end points) set at intervals of 2 mm at the end are the length portions excluding the length portion of 3 mm inward from both ends of the ridgeline. Does not match the end of. On the other hand, in the example of FIG. 2, as a result of setting the measurement points at intervals of 2 mm from the start point, the points (end points) set at intervals of 2 mm at the end are the length portions excluding the length portion of 3 mm inward from both ends of the ridgeline. Consistent with the end.

That is, the method of taking the measurement points of the ridge line 13 in the present invention is to remove 3 mm inward from both ends of the ridge line, start from a point 3 mm inward from one end, and measure points from the start point to the end point at intervals of 2 mm on the ridge line. If the distance from the other end is less than 3 mm, the measurement point shall not be set. By defining in this way, even when the length of the ridge line 13 includes an even value, an odd value, and a significant numerical value after the decimal point (for example, when the ridge line length of the orientation flat is 22.2 mm), the above maximum The deviation can be evaluated.

In the indium phosphide substrate 10, the maximum value of the above-mentioned deviation is controlled to be 1/1000 or less of the length of the ridge line 13. According to such a configuration, when the indium phosphide substrate 10 is observed from above the main surface 11 with an optical microscope or the like and the orientation flat 12 is used as a reference for determining the orientation of the wafer, the main surface 11 and the orientation flat 12 The accuracy of the linearity of the ridge line 13 in contact with the wafer is improved, and the wafer can be accurately determined in a desired direction.

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

[Manufacturing method of indium phosphide substrate]
Next, a method for producing an indium phosphide substrate according to the embodiment of the present invention will be described. The method for producing an indium phosphide substrate according to the embodiment of the present invention includes a first production method and a second production method. FIG. 4 shows a schematic view of each step of the first manufacturing method and the second manufacturing method, and the ingot or wafer manufactured in each step.

(First manufacturing method)
As a first method for producing an indium phosphide substrate, first, an ingot of indium phosphide is produced by a known method.
Next, the ingot of indium phosphide is ground with a grindstone having a count of # 270 to # 400 at a grindstone feed rate of 20 to 35 mm / min to form a cylinder, and an orientation flat (OF) is formed.
In the technical field to which the present invention belongs, the number used as the above-mentioned "count #" corresponds to the particle size of the grindstone. The larger the number of the count #, the smaller the grain size of the grindstone, and the smaller the number, the smaller the grain size of the grindstone. big.
Further, the "grindstone feed rate" indicates the speed at which the grindstone rotation axis moves relative to the ingot in a state where the rotating grindstone is pressed against the ingot of ingot for grinding.
Next, a wafer having a main surface and an orientation flat is cut out from the ground indium phosphide ingot. 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 are cut out to a predetermined thickness.
Next, in the wafer, the outer peripheral portion other than the end face constituting the orientation flat is chamfered. Here, the outer peripheral portion other than the end face constituting the orientation flat is shown as a "grinding allowance" in the chamfering (wafer grinding) step of the first manufacturing method of FIG.
Next, at least one surface, preferably both sides, of the chamfered wafer is polished. The polishing process is also called a lapping process, and the unevenness of the wafer surface is removed by polishing with a predetermined abrasive.
Next, the polished wafer is etched under the following etching conditions.
Etching conditions [Etching liquid composition] When 85% by mass of phosphoric acid aqueous solution and 30% by mass of hydrogen peroxide solution are used, the phosphoric acid aqueous solution: 0.2 to 0.4 and the hydrogen peroxide solution: 0.1. , Remaining: Water, set the volume ratio so that the entire etching solution is 1. [Etching solution temperature] 60 to 100 ° C.
[Etching time] 8 to 15 minutes The wafer is etched by immersing the entire wafer in the etching solution.
Next, the main surface of the wafer is polished with an abrasive for mirror polishing to finish it as a mirror surface.
Next, by washing, the indium phosphide wafer according to the embodiment of the present invention is produced.

In the first method for manufacturing an indium phosphide substrate, the straightness of the ridgeline portion of the orientation flat is improved by optimizing the conditions for forming an orientation flat on the ingot of indium phosphide and the etching conditions for the wafer after polishing. I'm in control.

(Second manufacturing method)
As a second method for producing an indium phosphide substrate, first, an ingot of indium phosphide is produced by a known method.
Next, the ingot of indium phosphide is ground into a cylinder and an orientation flat (OF) is formed.
Next, a wafer having a main surface and an orientation flat is cut out from the ground indium phosphide ingot. 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 are cut out to a predetermined thickness.
Next, on the wafer, the end face portion of the orientation flat is ground with a grindstone having a count of # 800 to # 1200 at a grindstone feed rate of 60 to 180 mm / min. The "grindstone feed rate" is the speed at which the contact portion between the outer peripheral portion of the wafer and the grindstone moves relative to the outer peripheral portion of the wafer in a state where the rotating grindstone is pressed against the outer peripheral portion of the wafer for grinding. show. The outer peripheral grinding portion in this step is the portion shown as the "grinding allowance" in the chamfering (wafer grinding) step of the second manufacturing method in FIG. 4, but the orientation flat portion is not chamfered and only the end face is used. Grind. The outer peripheral portion other than the orientation flat portion is chamfered.
Next, at least one surface, preferably both sides, of the chamfered wafer is polished. The polishing process is also called a lapping process, and the unevenness of the wafer surface is removed by polishing with a predetermined abrasive.
Next, the polished wafer is etched under the following etching conditions.
Etching conditions [Etching liquid composition] When 85% by mass of phosphoric acid aqueous solution and 30% by mass of hydrogen peroxide solution are used, the phosphoric acid aqueous solution: 0.2 to 0.4 and the hydrogen peroxide solution: 0.1. , Remaining: Water, set the volume ratio so that the entire etching solution is 1. [Etching solution temperature] 60 to 100 ° C.
[Etching time] 8 to 15 minutes The wafer is etched by immersing the entire wafer in the etching solution.
Next, the main surface of the wafer is polished with an abrasive for mirror polishing to finish it as a mirror surface.
Next, by washing, the indium phosphide wafer according to the embodiment of the present invention is produced.

In the second manufacturing method of the indium phosphide substrate, the linearity of the ridgeline portion of the orientation flat is controlled by optimizing the grinding conditions of the end face portion of the orientation flat of the wafer and the etching conditions of the wafer after polishing. ing.

The grinding conditions of the end face portion of the orientation flat of the wafer in the second manufacturing method of the indium phosphide substrate are the same as, for example, the ingot grinding conditions in the first manufacturing method of the indium phosphide substrate described above, or more. It is difficult to satisfactorily control the linearity of the ridge line as in the indium phosphide substrate according to the embodiment of the present invention only by finely grinding. This is because the grinding method differs between ingot grinding and wafer grinding, and wafer grinding may cause the wafer to vibrate, especially during grinding.

A semiconductor epitaxial wafer can be produced by epitaxially growing a semiconductor thin film on the indium phosphide substrate according to the embodiment of the present invention by a known method. As an example of the epitaxial growth, a HEMT structure in which an InAlAs buffer layer, an InGaAs channel layer, an InAlAs spacer layer, and an InP electron supply layer are epitaxially grown may be formed on an indium phosphide substrate. When producing a semiconductor epitaxial wafer having such a HEMT structure, generally, a mirror-finished indium phosphide substrate is subjected to an etching treatment with an etching solution such as sulfuric acid / hydrogen peroxide solution, and silicon adhered to the substrate surface. Remove impurities such as (Si). In general, the amount of etching removed here is insignificant and does not change the ridgeline of the orientation flat portion. Then, an epitaxial film is formed on the indium phosphide substrate after this etching treatment by a molecular beam epitaxial epitaxy (MBE) or a metalorganic chemical vapor deposition (MOCVD).

Hereinafter, examples for better understanding the present invention and its advantages will be provided, but the present invention is not limited to these examples.

・ Test Example 1
Based on the production flow of the first production method described above, Examples 1 to 4 and Comparative Examples 1 to 4 were produced as follows.
First, a single crystal ingot of indium phosphide grown with a diameter of φ80 mm or more was prepared.
Next, the outer circumference of the ingot of a single crystal of indium phosphide was ground to form a cylinder, and an orientation flat (OF) was formed. Regarding the outer peripheral grinding of the ingot, the count and metal bond shown in Table 1 were adopted as the grindstone, and the grindstone feed rate shown in Table 1 was used.
Next, a wafer having a main surface and an orientation flat was 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, and a plurality of wafers were cut out to a predetermined thickness.
Next, in the wafer, the outer peripheral portion other than the end face constituting the orientation flat was chamfered.
Next, the unevenness of the wafer surface was removed by polishing both sides of the chamfered wafer with an abrasive.
Next, the wafer was immersed in an etching solution and etched at a predetermined temperature for a predetermined time. Table 1 shows the etching conditions. The "phosphoric acid aqueous solution" shown in Table 1 uses an 85% by mass phosphoric acid aqueous solution, the "hydrogen peroxide solution" uses a 30% by mass hydrogen peroxide solution, and the "sulfuric acid" uses 96% by mass of sulfuric acid. Using.
Next, the main surface of the wafer was polished with an abrasive for mirror polishing to give a mirror surface, and then washed to prepare 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 have a length of 22 mm.

・ Test Example 2
As Example 5, an indium phosphide substrate was prepared in the same manner as in Examples 1 to 4 described above except for the following points (1) and (2).
(1) A single crystal ingot of indium phosphide grown with a diameter of φ104 mm or more was prepared.
(2) The main surface of the wafer was polished with an abrasive for mirror polishing to give a mirror surface, and then washed to prepare 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 have a length of 32.5 mm.

・ Test example 3
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 follows.
First, a single crystal ingot of indium phosphide grown with a diameter of φ80 mm or more was prepared.
Next, the outer circumference of the ingot of a single crystal of indium phosphide was ground to form a cylinder, and an orientation flat (OF) was formed. Regarding the outer peripheral grinding of the ingot, the number and metal bond shown in Table 2 were adopted as the grindstone, and the grindstone feed rate shown in Table 2 was used.
Next, a wafer having a main surface and an orientation flat was 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, and a plurality of wafers were cut out to a predetermined thickness.
Next, in the wafer, the end face portion of the orientation flat was ground. For the grindstone used for the grinding, the counts shown in Table 2 were adopted, and the grindstone feed speeds shown in Table 2 were used. The outer peripheral part other than the orientation flat part was chamfered.
Next, the unevenness of the wafer surface was removed by polishing both sides of the chamfered wafer with an abrasive.
Next, the wafer was immersed in an etching solution and etched at a predetermined temperature for a predetermined time. Table 2 shows the etching conditions. The "phosphoric acid aqueous solution" shown in Table 2 uses an 85% by mass phosphoric acid aqueous solution, the "hydrogen peroxide solution" uses a 30% by mass hydrogen peroxide solution, and the "sulfuric acid" uses 96% by mass of sulfuric acid. Using.
Next, the main surface of the wafer was polished with an abrasive for mirror polishing to give a mirror surface, and then washed to prepare 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 have a length of 22 mm.

・ Test Example 4
As Example 10, an indium phosphide substrate was prepared in the same manner as in Examples 6 to 9 described above except for the following points (1) and (2).
(1) A single crystal ingot of indium phosphide grown with a diameter of φ104 mm or more was prepared.
(2) The main surface of the wafer was polished with an abrasive for mirror polishing to give a mirror surface, and then washed to prepare 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 have a length of 32.5 mm.

(Evaluation 1)
With respect to the indium phosphide substrates according to Examples 1 to 4, Examples 6 to 9 and Comparative Examples 1 to 8, the interval of 2 mm is provided in a total length portion of 16 mm excluding the length portion of 3 mm inward from both ends of the ridgeline. A total of 9 measurement points from the start point to the end point were set in. Next, the straight line connecting the start point and the end point was used as the reference line, and the distance from the reference line of each measurement point was used as the deviation of each measurement point. Next, the deviations at a total of 7 measurement points excluding the start point and the end point were evaluated, and the maximum one was taken as the maximum deviation. In addition, the ratio of the maximum deviation to the ridgeline length was calculated.

(Evaluation 2)
Regarding the indium phosphide substrates according to Examples 5 and 10, a total of 14 from the start point to the end point at intervals of 2 mm in a total length portion of 26.5 mm excluding the length portion of 3 mm inward from both ends of the ridgeline. One measurement point was set. Next, the straight line connecting the start point and the end point was used as the reference line, and the distance from the reference line of each measurement point was used as the deviation of each measurement point. Next, the deviations at a total of 12 measurement points excluding the start point and the end point were evaluated, and the maximum one was taken as the maximum deviation. In addition, the ratio of the maximum deviation to the ridgeline length was calculated.
Tables 1 and 2 show the above-mentioned manufacturing conditions and the results of evaluation 1 and evaluation 2.

(Evaluation results)
In Examples 1 to 10, the maximum deviation value is 1/1000 or less of the length of the ridge line, and the indium phosphide substrate having good linearity accuracy of the ridge line where the main surface and the orientation flat are in contact is obtained. Obtained.
In Comparative Examples 1, 4, 5 and 8, the liquid composition used in the etching was not appropriate under the ridge line forming conditions, and the maximum deviation value exceeded 1/1000 of the ridge line length.
In Comparative Example 2, the grain size of the grindstone used in the ingot outer peripheral grinding was not appropriate under the ridge line forming conditions, and the maximum deviation value exceeded 1/1000 of the length of the ridge line.
In Comparative Example 3, the grindstone feed rate set by the ingot outer peripheral grinding was not appropriate under the ridge line forming conditions, and the maximum deviation value exceeded 1/1000 of the ridge line length.
In Comparative Example 6, the grain size of the grindstone used for grinding the outer periphery of the wafer was not appropriate under the ridge line forming conditions, and the maximum deviation value exceeded 1/1000 of the length of the ridge line.
In Comparative Example 7, the grindstone feed rate set in the wafer outer peripheral grinding was not appropriate under the ridge line forming conditions, and the maximum deviation value exceeded 1/1000 of the ridge line length.

10 Indium phosphide substrate 11 Main surface 12 Orientation flat 13 Ridge line

Claims (4)

An indium phosphide substrate having a main surface and an orientation flat.
In the ridge line where the main surface and the orientation flat are in contact with each other, a plurality of measurement points from the start point to the end point are set at intervals of 2 mm on the ridge line, excluding a portion having a length of 3 mm inward from both ends of the ridge line. When the straight line connecting the start point and the end point is used as a reference line and the distance of each measurement point from the reference line is taken as the deviation of each measurement point, the maximum value of the deviation is 1000 of the length of the ridge line. der less than one minute is,
The maximum diameter of the main surface is 49～151Mm, indium phosphide substrate the length of the ridge, characterized in 8-50% der Rukoto diameter of said main surface. The indium phosphide substrate according to claim 1, wherein the maximum value of the deviation is 1/1500 or less of the length of the ridgeline. The indium phosphide substrate according to claim 1 or 2, wherein the substrate thickness is 300 to 900 μm. The outer edge of the main surface is composed of the orientation flat and an arc portion connected to the orientation flat, and the maximum diameter of the main surface is equal to or larger than the length of the ridgeline and is 49 to 151 mm. The indium phosphide substrate according to any one of 3.

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