JP2018207097A - Substrate for semiconductor and manufacturing method of the same - Google Patents

Abstract

To provide a substrate for a semiconductor without deformation or with less deformation even when deposition or high-temperature heat treatment is performed; and provide a manufacturing method of the substrate for a semiconductor.SOLUTION: The substrate for a semiconductor comprises one surface having a convex SORI and another surface having a concave SORI of similar degree, in which thickness variation is equal to or less than 3 μm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor substrate and a method for manufacturing the same.

  In semiconductor integrated circuits (LSIs: Large Scale Integration) and TFT-LCDs (Thin Film Transistor-Liquid Crystal Displays), there is an increasing demand for miniaturization and high-speed operation. It is getting more precise.

If the flatness of the substrate for the polysilicon TFT is impaired, inconveniences such as non-adsorption or gripping may occur when the glass wafer is chucked or transported by the robot in the manufacturing process of the liquid crystal display device. In a photolithography process for applying a fine pattern in the process of forming a TFT, there arises a disadvantage that pattern superposition is deteriorated.
Further, in the liquid crystal panel, if the flatness of the two transparent glass bodies does not match, the film thickness of the liquid crystal sandwiched between the transparent glass bodies is difficult to be uniform, and color unevenness or the like occurs, resulting in inconvenience in quality.
Further, when a TFT-LCD is manufactured using a polysilicon thin film, the processing temperature reaches 1000 ° C. or higher, so that the substrate undergoes viscous deformation and warpage deformation occurs.

In order to solve these problems, for example, Patent Document 1 discloses a method of providing an active element substrate made of a quartz glass material having excellent heat resistance and high purity by suppressing the content of hydroxyl group concentration and chlorine concentration. Proposed.
Further, Patent Document 2 proposes a method in which the silicon nitride film is formed on the front and back surfaces of the substrate, so that the stress of the silicon nitride film is canceled by the back surface of the substrate and the substrate is not warped.
Furthermore, in Patent Document 3, by using quartz glass that has a fluorine concentration within a certain range and substantially does not contain an alkali metal oxide, the density change due to fictive temperature is reduced, and dimensional stability before and after high-temperature treatment. A method for obtaining a quartz glass substrate for a polysilicon TFT LCD excellent in the above is disclosed.

JP-A-6-11705 Japanese Patent Laid-Open No. 11-121760 JP 2005-215319 A

However, in the method of Patent Document 1, even if the flatness of the quartz glass material is improved, the subsequent deformation of the polysilicon thin film due to the film stress cannot be suppressed.
Further, in the method of Patent Document 2, it is impossible to eliminate the occurrence of warping unless the same film is formed on the front and back surfaces of the substrate. However, it is common that both the TFT side and the color filter side are formed of the same film. Therefore, it is difficult to suppress deformation even with this method.
Furthermore, the method of Patent Document 3 is excellent in dimensional stability before and after high-temperature processing, but cannot suppress deformation due to film stress.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a semiconductor substrate that is not deformed or has little deformation even when film formation or high-temperature heat treatment is performed, and a method for manufacturing the same.

  As a result of intensive studies to achieve the above object, the present inventors have used a manufacturing apparatus such as a double-sided lapping apparatus, a single-sided lapping apparatus, a double-side polishing apparatus, or a single-side polishing apparatus that is usually used in the manufacture of semiconductor substrates. It is possible to manufacture a semiconductor substrate with low cost, good reproducibility, SORI and BOW arbitrarily controlled, and small variations in thickness. More specifically, the above-described apparatus deforms the semiconductor substrate by film stress or high-temperature heat treatment. Assuming that the amount of deformation is taken into consideration in advance, a substrate having a shape that is intentionally warped in the opposite direction of these deformations can be deformed even when film formation or high-temperature heat treatment is performed. The present invention has been completed by finding that a semiconductor substrate with little or no deformation can be obtained.

That is, the present invention
1. A semiconductor substrate comprising one surface having a convex SORI and the other surface having a concave SORI of the same degree as the SORI, and having a thickness variation of 3 μm or less,
2. 1 a semiconductor substrate having a SORI of 50 to 600 μm on each surface;
3. 1 or 2 semiconductor substrates, wherein the BOW of one surface having the convex SORI is +25 to +300;
4). The semiconductor substrate according to any one of 1 to 3, wherein the BOW on the other surface having the concave SORI is −25 to −300,
5. The semiconductor substrate according to any one of 1 to 4 having a thickness of 0.5 to 3 mm,
6). The semiconductor substrate according to any one of 1 to 5, wherein the semiconductor substrate has a circular shape with a diameter of 100 to 450 mm or a rectangular shape with a diagonal length of 100 to 450 mm in plan view,
7). Any one of the semiconductor substrates 1 to 6 made of synthetic quartz glass;
8). A semiconductor substrate according to any one of 1 to 7 which is a polysilicon TFT substrate;
9. It has a front surface and a back surface, passes through an intermediate point on the center line connecting the center points of the front and back surfaces, and has a thickness variation such as SORI in which the front surface and the back surface face each other symmetrically with respect to a plane orthogonal to the center line. A preparation step for preparing a transfer master, and two raw material substrates are installed in a double-sided lapping apparatus so as to sandwich the transfer master, and a surface of each raw material substrate that is not in contact with the transfer master is processed. The transfer process for producing two transfer substrates each having the transfer master shape transferred to one side, and the shape of the transfer master by wrapping both surfaces of the transfer substrate or in the transfer step on the transfer substrate A lapping process for producing a lapping substrate by lapping only a surface to which no transfer is made, and polishing both surfaces or one surface of the lapping substrate Method of manufacturing a conductor substrate,
10. It has a front surface and a back surface, passes through an intermediate point on the center line connecting the center points of these front and back surfaces, and either one of the front and back surfaces is parallel to a surface orthogonal to the center line, And a preparation step of preparing a transfer master in which the other surface in contact with the raw material substrate is orthogonal to the center line and symmetrical with respect to the center line, and the other of the transfer masters The raw material substrate is placed in a single-sided lapping machine so as to be in contact with the surface, and the surface of the raw material substrate that is not in contact with the transfer master is processed to produce a transfer substrate in which the shape of the transfer master is transferred to one surface. A lapping substrate is produced by wrapping both sides of the transfer substrate and the transfer substrate, or by wrapping only the surface of the transfer substrate where the shape of the master for transfer is not transferred in the transfer step. A lapping step that provides a method for manufacturing a semiconductor substrate, characterized by polishing the both sides or one side of the lapping board.

ADVANTAGE OF THE INVENTION According to this invention, the semiconductor substrate which has predetermined | prescribed SORI and thickness variation which considered the deformation | transformation of the semiconductor substrate by a film stress or high temperature heat processing previously can be provided. Therefore, a semiconductor substrate having a desired shape can be obtained even when film formation or high-temperature heat treatment is subsequently performed.
In addition, the semiconductor substrate of the present invention can be manufactured with low cost and good reproducibility using a double-sided lapping device or a single-sided lapping device, or a double-sided polishing device or a single-sided polishing device that is usually used in the production of a semiconductor substrate.

FIG. 4 shows the SORI mode of the semiconductor substrate of the present invention, where (A) shows a state in which the convex shape is bent symmetrically with respect to the center, and (B) shows a convex shape in which the convex vertex is shifted from the center in the Y-axis direction. (C) shows a state of warping in a line-symmetric convex shape. In addition, the curve inside a surface shows the contour line showing height. It is explanatory drawing of SORI of the semiconductor substrate of this invention, S shows a least squares plane, a is the minimum value of the distance of the surface S and the surface of the semiconductor substrate A, b is the surface S and the semiconductor substrate A The maximum value of the distance to the surface. It is explanatory drawing of BOW of the board | substrate for semiconductors of this invention, e shows a front-back intermediate surface, S2 shows the reference plane obtained from e, f shows a board | substrate centerline, S2 and e which cross | intersect f In terms of distance, if e is above S2, + d is defined, and if it is below S2, −d is defined as BOW. It is a figure which shows the thickness dispersion | variation c of the board | substrate for semiconductors of this invention. It is the schematic which shows the transfer process using the double-sided lapping apparatus which concerns on 1st Embodiment of this invention. FIG. 3 is a side view showing a transfer master having a centrally symmetric SORI used in the first embodiment. It is the schematic which shows the lapping process using the double-sided lapping apparatus which concerns on 1st Embodiment. It is the schematic which shows the transcription | transfer process using the single-sided lapping apparatus which concerns on 2nd Embodiment of this invention. FIG. 10 is a side view showing a transfer master having a centrally symmetric SORI used in the second embodiment. It is the schematic which shows the lapping process using the single-sided lapping apparatus which concerns on 2nd Embodiment. FIG. 9 is a side view showing a transfer master having an SORI that is not centrally symmetric according to a modification of the first embodiment. FIG. 10 is a side view showing a transfer master having an SORI that is not centrally symmetric according to a modification of the second embodiment. It is the upper side figure and side view which show the master for transcription | transfer which concerns on the other modification of 1st Embodiment.

Hereinafter, the present invention will be specifically described.
A semiconductor substrate according to the present invention has one surface having a convex SORI and the other surface having a concave SORI of the same degree as this SORI, and has a thickness variation of 3 μm or less. To do.
In this way, the device is built by intentionally manufacturing a semiconductor substrate having a shape that is warped in the opposite direction to the deformation that occurs after film formation or high-temperature heat treatment before film formation or high-temperature heat treatment. In a rare stage or assembly stage, a semiconductor substrate having a desired shape can be obtained. Specifically, a semiconductor substrate having a shape that is warped in advance when it changes to a convex shape by a film forming process or a high-temperature heating process and that is warped in advance when it changes to a concave shape is manufactured.

The SORI in the semiconductor substrate of the present invention is not particularly limited as long as the finally obtained semiconductor substrate can be formed into a desired shape, but is preferably 50 to 600 μm, more preferably from the viewpoint of handling. Is 100 to 400 μm, more preferably 100 to 200 μm.
The aspect of the SORI in the present invention is not particularly limited. For example, when the semiconductor substrate is deformed into a convex shape with a central symmetry by film formation or a high-temperature heating process, a concave semiconductor substrate with a central symmetry is formed. (See FIG. 1A), and when the semiconductor substrate is convex and deforms into a convex shape with the center of the apex shifted in the Y-axis direction, a concave semiconductor substrate corresponding to the shift is formed. What is necessary is just to manufacture (refer FIG.1 (B)), and when a semiconductor substrate deform | transforms into the convex shape symmetrical with respect to the line which passes along a center, what is necessary is just to manufacture a concave semiconductor substrate with line symmetry (FIG. 1 (C)).

Here, as shown in FIG. 2, the SORI according to the present invention includes a minimum value (absolute value) a and a minimum value (absolute value) b between the least square plane S and the surface of the semiconductor substrate A. Sum (SORI = | a | + | b |).
If the substrate surface sufficiently reflects light and interference fringes with the apparatus reference surface are obtained, the SORI can be measured using an optical interference flatness tester. Conversely, if the substrate surface is rough and interference fringes cannot be obtained, the SORI can be obtained by scanning the laser displacement meter so as to sandwich the front and back of the substrate.

On the other hand, in the semiconductor substrate of the present invention, the thickness variation (TTV) is 3 μm or less, preferably 2 μm or less, more preferably in consideration of facilitating focusing during exposure and making the pattern thickness constant. 1 μm or less.
Here, the thickness variation means a value C obtained by subtracting the thickness of the thinnest portion from the thickness of the thickest portion in the plane of the substrate A, as shown in FIG. The thickness variation can be measured using an optical interference flatness tester or a laser displacement meter in the same manner as SORI.

In the semiconductor substrate of the present invention, it is preferable that the BOW of one surface having the convex SORI is +25 to +300, and the BOW of the other surface having the concave SORI is −25 to -300 is preferred.
In the present invention, the BOW quantifies the difference in height between the center of the substrate surface and the least mean square surface obtained as a surface reference. It is defined as adding a sign. Thereby, it is possible to determine whether the shape of the substrate is convex or concave at least in the center of the substrate.
When the SORI is convex, the BOW on one side is preferably +25 to +300, more preferably +25 to +200, even more preferably +25 to +100, and the BOW on the other side is preferably −25. It is -300, More preferably, it is -25--200, More preferably, it is -25--100.
On the other hand, when the SORI is concave, the BOW on one surface thereof is preferably −25 to −300, more preferably −50 to −200, still more preferably −50 to −100, and the other surface BOW is preferably +25 to +300, more preferably +50 to +200, and even more preferably +50 to +100.
In this way, in addition to the above-mentioned predetermined SORI, by defining the height of the center of the substrate like BOW, the convex and concave can be clarified as numerical values, and a semiconductor substrate having a desired shape can be obtained. Be able to get.

Here, as shown in FIG. 3, the BOW in the present invention is a distance d between the intersection of the reference surface S2 obtained from the front and back intermediate surface e and the substrate center line f orthogonal thereto and the front and back intermediate surface e. A value obtained by adding a sign to the absolute value d is defined as BOW if the front and back intermediate surface e is above the reference surface S2 and positive if the front and back intermediate surface e is below the reference surface S2.
When the substrate surface sufficiently reflects light and interference fringes with the apparatus reference surface are obtained, the BOW can be measured using an optical interference flatness tester. Conversely, when the substrate surface is rough and interference fringes cannot be obtained, the BOW can be obtained by scanning the laser displacement meter so as to sandwich the front and back of the substrate.

  The thickness of the semiconductor substrate is not particularly limited, but is preferably 0.5 to 3.0 mm, more preferably 0.6 to 1 from the viewpoint of substrate handling and a thickness that can be introduced into the exposure apparatus. .2 mm.

In the present invention, the shape of the semiconductor substrate is not particularly limited, and a general shape such as a circular shape or a rectangular shape can be adopted in a plan view. Moreover, although the diameter or diagonal length is not specifically limited, Preferably it is 100-450 mm, More preferably, it is 200-300 mm.
The material of the semiconductor substrate of the present invention is not particularly limited, and a conventionally known material such as a glass material or a ceramic material can be adopted. However, the substrate for the transmission type polysilicon TFT needs to transmit light. For this reason, a synthetic quartz glass substrate is preferable, and in the case of a reflective TFT, a polysilicon substrate is preferable.

As a manufacturing method of the semiconductor substrate of the present invention having the above-described SORI and BOW, a method of forming a desired shape in any of the slicing step, lapping step, and polishing step can be considered.
However, in the slicing process, in the case of cutting with a general wire saw, since the ingot is cut while applying the slurry containing the abrasive to the linearly stretched wire, the obtained semiconductor substrate is in the horizontal direction, that is, In the wire direction, it becomes linear following the wire. On the other hand, in the direction perpendicular to the wire direction on the surface of the semiconductor substrate, a method of lowering or raising the ingot is adopted, but this direction is a mechanism that moves linearly with good reproducibility, so it is curved. It is difficult to move to and arbitrarily control SORI and BOW.
Further, since the semiconductor substrate has a relatively small thickness with respect to the diameter, there are few repetitive stresses of the substrate which becomes a driving force for creating a desired SORI shape in the lapping process or the polishing process. Therefore, since the SORI and BOW are maintained even if the lapping process progresses, the substrate shape can be freely controlled by making the surface SORI convex, ie BOW plus, and the back SORI concave, ie BOW minus. Difficult to do.

Therefore, in the present invention, a semiconductor substrate having a desired SORI and BOW shape is manufactured in a lapping process using a transfer master. The shape of the transfer master used in the present invention differs depending on the type of the lapping device used in the transfer process and the shape of the target semiconductor substrate.
For example, when a double-sided lapping apparatus is used, a centrally symmetric SORI-shaped semiconductor substrate has a front surface and a back surface, passes through an intermediate point on the center line connecting the center points of the front and back surfaces, and is a surface orthogonal to the center line. A preparation step for preparing a transfer master having a thickness variation and a SORI in which the front and back surfaces face each other symmetrically, and two raw material substrates are installed in a double-sided lapping machine so as to sandwich the prepared transfer master. , A transfer step of processing the surface of each raw material substrate that is not in contact with the transfer master, and producing two transfer substrates each having the shape of the transfer master transferred to one side, and the transfer substrate obtained in this transfer step A lapping process that wraps both surfaces, or wraps only the surface of the transfer substrate where the shape of the transfer master is not transferred, It can be produced by polishing the one surface.

  When a single-sided lapping apparatus is used, a centrally symmetric SORI-shaped semiconductor substrate has a front surface and a back surface, passes through an intermediate point on the center line connecting the center points of the front and back surfaces, and is a surface orthogonal to the center line. For the transfer, either one of the front and back surfaces is parallel and the other surface of the front and back surfaces in contact with the raw material substrate is orthogonal to the center line and symmetric with respect to the center line. Place the raw material substrate on the single-sided lapping machine so as to contact the other side of the prepared master for transfer and prepare the master, and process the surface of the raw material substrate that does not contact the master for transfer to Create a lapping substrate by wrapping both sides of the transfer substrate, or wrapping only the surface of the transfer substrate on which the shape of the transfer master is not transferred. And-up process, can be produced by polishing the both sides or one side of the lapping board.

The double-sided lapping device and single-sided lapping device used in the present invention are not particularly limited, and can be appropriately selected from known devices.
The rotational speed of the double-sided lapping device and single-sided lapping device in the transfer process is preferably 5 to 50 rpm, and the load is preferably 10 to 200 g / cm ^{2. In} the double-sided lapping device, the machining allowance per unit time is almost the same on both sides. It is preferable that

The material of the transfer master is not particularly limited, and alumina ceramic, metal, resin, or the like can be adopted, but alumina ceramic is preferable from the viewpoint of deformation and breakage.
Moreover, as an abrasive | polishing agent, in addition to using the alumina type abrasive | polishing material with an average particle diameter of preferably 5-20 micrometers dispersed 20-20 mass% with water, silicon carbide type | system | group, an artificial diamond, etc. are also used. it can.

In the transfer process, when using a double-sided lapping machine, as described above, the two raw material substrates are enclosed in a carrier so as to sandwich the master for transfer, and the lower lapping platen and the upper lapping platen are respectively placed on the double-sided lapping machine. Install and process.
Usually, the double-sided lapping machine adjusts the thickness of the carrier in accordance with the thickness of one raw material substrate. In the case of the present invention, however, the carrier in consideration of the thickness of the two raw material substrates and the master for transfer. It is preferable to set the thickness of the film thick. Others can be processed in the same manner as normal lapping.
At this stage, since one side of each of the two raw material substrates will be processed at the same time, the shape of the master for transfer is transferred only on one side contacting the lower lap surface plate and the upper lap surface plate, Since the surface in contact with the transfer master is not processed, it does not change.

Since the center of the transfer master is thicker than the outer periphery, the processing pressure of the raw material substrate and the lapping platen is concentrated at the center of the raw material substrate in the initial stage of the transfer process. At this time, since the raw material substrate is thin and has little repulsive force, cutting proceeds selectively from the center of the raw material substrate. When cutting progresses and the processing reaches the outer periphery of the raw material substrate, the shape of the transfer master is finally formed on the opposite surface of the raw material substrate that is not in contact with the transfer master (that is, the surface that is in contact with the lapping platen). Is transcribed.
When the outer peripheral portion of the transfer master is thinner than the central portion, the outer peripheral portion of the raw material substrate obtained in the transfer process becomes thicker than the central portion according to the difference in thickness between the outer peripheral portion and the central portion. Conversely, when the outer peripheral portion of the transfer master is thicker than the central portion, the outer peripheral portion of the raw material substrate obtained in the transfer process becomes thinner than the central portion according to the difference in thickness between the outer peripheral portion and the central portion. In this manner, a transferred shape can be created according to the shape of the transfer master.

  On the other hand, when using a single-sided lapping machine in the transfer process, a transfer master is installed between the raw material substrate and the top plate of the single-sided lapping machine so that the flat surface faces the top plate, The material substrate is processed after fixing the carrier to the top plate so that the transfer master does not fall off in the lateral direction. The raw material substrate is processed by the lower wrap surface plate of the single-sided lapping device, and as the processing proceeds, the shape of the transfer master is transferred only to the surface in contact with the lower wrap surface plate side of the raw material substrate.

The transfer substrate that has undergone the above transfer process is lapped using a double-sided lapping device or a single-sided lapping device. As for the rotation speed of a double-sided lapping device and a single-sided lapping device, 5-50 rpm is preferable for all, and the load is preferably 10-200 g / cm ² .
When using a double-sided lapping device, a transfer substrate is set so that the flat surface faces the upper lapping platen side of the double-sided lapping device, a carrier is provided to prevent the substrate from falling off, and normal lapping is performed. As a result, a lapping substrate is obtained in which the upper surface is lapped and the lower surface is lapped. The SORI value of the lapping substrate is about half of the SORI value before lapping, but the degree of decrease also depends on the diameter and thickness of the transfer substrate.
The principle that the shape of the front and back surfaces is created is that, due to the thickness variation that already exists in the initial shape, an in-plane processing pressure difference occurs on both sides from the initial processing, and the part to be cut is selectively and over time. Change. Therefore, the processing pressure distribution in the substrate surface also changes accordingly, and processing proceeds. As a result, the substrate shape before the original lapping process is reflected in the shape of both sides while being halved, depending on the repetitive force of the transfer substrate, that is, the diameter and thickness of the transfer substrate.

  When using a single-sided lapping machine, install a transfer substrate between the lower wrap surface plate and the top plate so that the flat surface faces the lower wrap surface plate, and the transfer substrate will not fall off in the horizontal direction. A lapping process is performed by providing a carrier. In this case, since only the non-transferred surface is lapped, the SORI of the transfer side surface of the original master for transfer and the SORI of the obtained lapping substrate are equivalent.

The lapping substrate obtained in the lapping step is further subjected to a polishing step for polishing both sides or one side as necessary for mirror finishing.
In the polishing step, a double-side polishing apparatus or a single-side polishing apparatus can be used. The surface to be mirrored may be either a surface having convex SORI and BOW plus or a surface having concave SORI and BOW minus.
Thus, finally, various semiconductor substrates having desired shapes (SORI and BOW) as shown in FIG. 1 can be produced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 5 shows an embodiment of a transfer process using the double-sided lapping apparatus 1 according to the first embodiment of the present invention.
In this embodiment, as shown in FIG. 5, the two raw material substrates 11, 11 are encapsulated in the carrier 12 so as to sandwich the transfer master 10, and the lower side of the double-sided lapping apparatus 1. It is installed on the lap platen 13 and the upper lap platen 14.

  As shown in FIG. 6, the transfer master 10 used in this embodiment has center points 100A, 100A on the center line L1 passing through the center point 100A of the front surface 100 and the center point 110A of the back surface 110. The virtual surface S1 that passes through the intermediate point M1 of 110A and is orthogonal to the center line L1 has a convex SORI and thickness variation in which the front surface 100 and the back surface 110 face each other symmetrically, and the center line L1 The front and back surfaces are symmetrical.

  In addition, the raw material substrate 11 used in the present embodiment is manufactured by slicing a synthetic quartz glass ingot using a wire saw, performing chamfering, and removing the saw marks on the front and back surfaces with a double-sided lapping apparatus, and has a diameter of 100 mm. It has a disk shape with a thickness of 630 μm, SORI on the front and back surfaces of 6 μm, BOW on the front and back surfaces of +3 μm and −3 μm, and a thickness variation of 1 μm, respectively.

With the two raw material substrates 11 installed as described above, one side of each raw material substrate 11 is simultaneously processed at a rotational speed of 20 rpm and a load of 100 g / cm ² of the double-sided lapping machine 1 and transferred to one side. A transfer substrate onto which the shape of the master 10 has been transferred is obtained.
Subsequently, as shown in FIG. 7, one of the transfer substrates 11 </ b> A on which the shape of the transfer master 10 is transferred on one side is directed so that the flat surface faces the upper lap platen 14 side of the double-sided lapping apparatus 1. By placing inside the carrier 12 and performing double-sided lapping at a rotation speed of 20 rpm and a load of 100 g / cm ² , and transferring the shape of the master 10 for transfer on the surface that has not been transferred in the transfer process, A lapping substrate having a side surface convex and a bottom surface concaved is obtained.

  With respect to the obtained lapping substrate, both surfaces are mirror-finished by a double-side polishing apparatus (not shown) to obtain a synthetic quartz glass substrate having a centrally symmetric SORI as shown in FIG. Specifically, it has a convex shape with a SORI of 50 μm on the front surface, a BOW of +25 μm, a concave shape with a SORI of 50 μm on the back surface, a BOW of −25 μm, an in-plane thickness variation of 1 μm, and a thickness of 500 μm. A synthetic quartz glass substrate having mirror surfaces on both sides is obtained.

FIG. 8 shows an embodiment of the transfer process using the single-sided lapping device 2 according to the second embodiment of the present invention. In the second embodiment, the same members as those in the first embodiment are denoted by the same reference numerals.
As shown in FIG. 9, the transfer master 20 used in this embodiment has center points 200 </ b> A, 200 </ b> A at the center line L <b> 2 passing through the center point 200 </ b> A of the front surface 200 and the center point 210 </ b> A of the back surface 210. The front surface 200 is parallel (flat surface) to the virtual surface S2 that passes through the intermediate point M2 of 210A and is orthogonal to the center line L2, and the back surface 210 is orthogonal to the center line L2, and the center line L2 The shape is along a symmetrical convex shape.

  In addition, the raw material substrate 21 used in the present embodiment is a disk-shaped device manufactured by the same method as that of the first embodiment and having a diameter of 200 mm, a thickness of 855 μm, a front surface and rear surface side SORI of 6 μm, and a thickness variation of 1 μm. This is a synthetic quartz glass substrate.

As shown in FIG. 8, the transfer master 20 is arranged so that the flat surface faces the top plate 25, and the raw material substrate 21 is placed in contact with the surface along the convex shape of the transfer master 20. Only the surface of the raw material substrate 21 that does not contact the transfer master 20 at a rotational speed of 20 rpm and a load of 100 g / cm ² in a state of being installed in the single-sided wrapping device 2 and enclosed in the carrier 12 is the lower wrap surface plate 13. The transfer substrate having the shape of the transfer master 20 transferred on one side can be obtained by processing at.

Subsequently, as shown in FIG. 10, the transfer substrate 21 </ b> A having the shape of the transfer master 20 transferred on one side is transferred between the lower wrap surface plate 13 and the top plate 25 of the single-side lap device 2. In a state where the surface of the master 20 for transfer is placed in the carrier 12 in a state where the surface is directed to the top plate 25 side, one-side lapping is performed at a rotation speed of 20 rpm and a load of 100 g / cm ² . By transferring the shape of the master 20 for transfer also on the surface that has not been transferred, a lapping substrate is obtained in which the upper surface is lapped and the lower surface is lapped.

  The obtained lapped substrate is mirror-finished on both sides in the same manner as in the first embodiment to obtain a synthetic quartz glass substrate having a centrally symmetric SORI as shown in FIG. Specifically, a convex shape with a surface of SORI of 100 μm and a BOW of +50 μm, a concave surface of a back surface of 110 μm with a SORI of 110 μm and a BOW of −50 μm, an in-plane thickness variation of 1 μm, and a thickness of 725 μm on both sides are combined. A quartz glass substrate is obtained.

  The shape, thickness and SORI of the transfer master used in the method for manufacturing a semiconductor substrate of the present invention, the shape and material of the raw material substrate, the specific conditions for each processing, etc. are limited to the above embodiments. The present invention includes modifications and improvements as long as an object and an effect of the present invention can be achieved.

For example, when a semiconductor substrate having SORI that is not centrally symmetric is manufactured using a double-sided lapping apparatus, a transfer master 30 as shown in FIG. 11 may be used in the first embodiment.
The master 30 for transfer is on a virtual plane S3 passing through the midpoint M3 between the vertices 300A and 310A in the straight line L3 passing through the vertex 300A of the front surface 300 and the vertex 310A of the back surface 310, and perpendicular to the straight line L3. It has a convex SORI in which the front surface 300 and the back surface 310 face each other symmetrically.
By using this transfer master 30 and performing transfer processing, lapping processing, polishing processing and the like in the same manner as in the first embodiment, the convex apex as shown in FIG. Thus, a semiconductor substrate having a convex shape deviating to BOW and having a negative BOW can be obtained.

Further, when manufacturing a semiconductor substrate having SORI that is not centrally symmetric using a single-sided lapping apparatus, a transfer master 40 as shown in FIG. 12 may be used in the second embodiment.
The master 40 for transfer passes through the intermediate point M4 between the vertex 410A and the partial point 400 in the straight line L4 passing through the vertex 410A of the back surface 410 and the partial point 400A on the front surface 400, and the straight line L4. The surface 400 is parallel (flat surface) to the orthogonal virtual surface S4, and the back surface 410 has a convex SORI.
By using this transfer master 40 and performing transfer processing, lapping processing, polishing processing, and the like in the same manner as in the second embodiment, the convex apex as shown in FIG. Thus, a semiconductor substrate having a convex shape deviating to BOW and having a negative BOW can be obtained.

  Furthermore, in the first embodiment, when an XY axis that is orthogonal to the surface of the transfer master as shown in FIG. 13 is provided, the thickness shape seen from the cross section in the X direction and the Y direction is the X direction. When a transfer master having a thickness variation symmetrical to a line (Y axis in FIG. 13) penetrating the center on the surface of the transfer master having a different inclination from the center to the outer periphery in the Y direction is used. A semiconductor substrate as shown in 1 (C) is obtained. In addition, the curve inside a board | substrate in FIG. 13 represents the contour line of thickness.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example.

[Example 1]
As a transfer master, one having a shape as shown in FIG. 6 was prepared. Specifically, both the front and back surfaces have the same convex shape of 110 μm, pass through an intermediate point on the center line connecting the center points of the front and back surfaces, and the front and back surfaces face each other symmetrically with respect to a plane orthogonal to the center line. An alumina ceramic transfer master having a thickness of 3 mm and a diameter of 100 mm with a thickness variation of 220 μm was prepared.
In addition, a synthetic quartz glass ingot was sliced using a wire saw E450E-12 manufactured by Toyo Advanced Technologies Co., Ltd., chamfered, and saw marks on the front and back surfaces were removed by a double-sided lapping machine. The diameter was 100 mm and the thickness was 630 μm. A raw material substrate having a SORI of 6 μm on the back surface and a thickness variation of 1 μm was prepared.
Two raw material substrates are placed on the lower wrap surface plate and the upper wrap surface plate of the double-sided wrapping device so as to sandwich the transfer master, and a wrap material whose main component is # 1000 alumina is used. Then, one side of each raw material substrate was simultaneously processed at a rotational speed of 20 rpm and a load of 100 g / cm ^{2 to} obtain two transfer substrates on which the shape of the transfer master was transferred on one side. As for the shape of the obtained transfer substrate, both sides warped 110 μm in a concave shape.

One of the obtained transfer substrates was placed in a double-sided lapping machine, and double-sided lapping was performed at a rotational speed of 20 rpm and a load of 100 g / cm ² using the same lapping material as in the above transfer process. The shape of the master for transfer was also transferred to the surface that was not transferred. Then, a lapping substrate having a convex shape with a SORI of 50 μm and a BOW of +25 μm on the front surface and a concave shape with a SORI of 50 μm and a BOW of −25 μm was obtained.
Furthermore, as a process of polishing both surfaces of the obtained lapping substrate, both surfaces are mirror-finished by a double-sided device, the surface is convex with SORI 50 μm and BOW is +25 μm, the back surface is concave with SORI 50 μm and BOW is +25 μm, A synthetic quartz glass substrate having an in-plane thickness variation (TTV) of 1 μm and a thickness of 500 μm on both sides was obtained.
Next, silane gas was supplied to the surface of the obtained synthetic quartz glass substrate, and after forming an amorphous silicon film, annealing treatment was performed to form a polysilicon film. As a result, the formed surface had a convex shape of SORI 122 μm, The other surface was changed to a concave shape of 122 μm SORI.
After that, when heat treatment at 1050 ° C. was further performed for 1 hour, the film-formed surface changed to a convex shape of SORI 4 μm, the other surface changed to a concave shape of SORI 4 μm, the in-plane thickness variation (TTV) was 1 μm, and it was almost flat. A synthetic quartz glass substrate for polysilicon TFT having SORI was obtained.

[Example 2]
After performing the transfer process in the same manner as in Example 1 using the double-sided wrapping device, the obtained transfer substrate is directed so that the surface onto which the shape of the transfer master is transferred faces the top plate side of the single-sided wrapping device. It was installed, and single-sided lapping was performed at a rotation speed of 20 rpm and a load of 100 g / cm ² to obtain a lapping substrate.
Further, both surfaces of the obtained lapping substrate were polished by the same method as in Example 1, the surface had a convex shape of SORI 110 μm and BOW was +55 μm, the back surface was a concave shape of SORI 110 μm and BOW was −55 μm, and the surface A synthetic quartz glass substrate having an inner thickness variation (TTV) of 1 [mu] m and a thickness of 500 [mu] m and mirror-finished surfaces was obtained.
Next, when a polysilicon film was formed on the obtained synthetic quartz glass substrate in the same manner as in Example 1, the formed surface was changed to a convex shape of SORI 122 μm and the other surface was changed to a concave shape of SORI 122 μm.
Thereafter, a heat treatment at 1050 ° C. was further performed for 1 hour. As a result, the film-formed surface was changed to a convex shape of SORI 4 μm, the other surface was changed to a concave shape of SORI 4 μm, and the in-plane thickness variation (TTV) was 1 μm, which was almost flat. A synthetic quartz glass substrate for a polysilicon TFT having an excellent SORI was obtained.

[Example 3]
As a transfer master, one having a shape as shown in FIG. 9 was prepared. Specifically, one surface of the front and back surfaces is flat, and the other surface is orthogonal to a center line connecting the centers of the front and back surfaces, and is warped 110 μm symmetrically with respect to the center line. An alumina ceramic transfer master having a shape and an in-plane thickness variation (TTV) of 110 μm and a central thickness of 2 mm and a diameter of 200 mm was prepared.
As a raw material substrate, a synthetic quartz glass substrate having a diameter of 200 mm, a thickness of 855 μm, a SORI on the front and back sides of 6 μm, and a thickness variation of 1 μm was prepared in the same manner as in Example 1.
The transfer master is installed between the raw material substrate and the top plate of the single-sided lapping machine so that the flat surface faces the top plate, and a wrap material whose main component is # 1000 alumina is used. Then, one side of the raw material substrate was processed at a rotational speed of 20 rpm and a load of 100 g / cm ² to obtain a transfer substrate on which the shape of the transfer master was transferred on one side. The shape of the obtained transfer substrate was flat on one side, and the other side warped 110 μm in a concave shape.

Next, a transfer substrate is placed between the lower wrap surface plate of the single-sided wrapping device and the top plate so that the transferred surface faces the top plate side of the single-sided wrapping device. Was used to perform single-sided lapping at a rotational speed of 20 rpm and a load of 100 g / cm ² to obtain a lapped substrate. The obtained lapping substrate obtained was a lapping substrate having a convex surface with a SOI of 110 μm and a concave surface with a back surface of 110 μm.
Further, the single side of the convex side is mirror-finished by a single-side polishing apparatus, the surface has a convex shape with SORI 110 μm and BOW is +55 μm, the back surface has a concave shape with SORI 110 μm and BOW is −55 μm, and the in-plane thickness variation (TTV) is 1 μm. Thus, a synthetic quartz glass substrate having a thickness of 725 μm was obtained.
When a polysilicon film was formed on the obtained synthetic quartz glass substrate in the same manner as in Example 1, the formed surface was changed to a convex shape of SORI 122 μm and the other surface was changed to a concave shape of SORI 122 μm.
After that, when heat treatment at 1050 ° C. was further performed for 1 hour, the film-formed surface changed to a convex shape of SORI 4 μm, the other surface changed to a concave shape of SORI 4 μm, the in-plane thickness variation (TTV) was 1 μm, and it was almost flat. A synthetic quartz glass substrate for polysilicon TFT having SORI was obtained.

[Example 4]
The transfer substrate obtained by performing the transfer process by the same method as in Example 3 is lapped on both sides by the same method as in Example 1, and the surface is convex with SORI 50 μm, and the back surface is a concave wrap with SORI 50 μm. A processed substrate was obtained.
Further, both surfaces are polished by the same method as in Example 1, the surface is convex with SORI 50 μm and BOW is +25 μm, the back surface is concave with SORI 50 μm and BOW is −25 μm, thickness variation is 1 μm, thickness A synthetic quartz glass substrate having a mirror surface of 725 μm was obtained.
When a polysilicon film was formed on the obtained synthetic quartz glass substrate in the same manner as in Example 1, the formed surface was changed to a convex shape of SORI 122 μm and the other surface was changed to a concave shape of SORI 122 μm.
After that, when heat treatment at 1050 ° C. was further performed for 1 hour, the film-formed surface changed to a convex shape of SORI 4 μm, the other surface changed to a concave shape of SORI 4 μm, the in-plane thickness variation (TTV) was 1 μm, and it was almost flat. A synthetic quartz glass substrate for polysilicon TFT having SORI was obtained.

[Example 5]
As a transfer master, one having a shape as shown in FIG. 11 was prepared. Specifically, the front and back surfaces are convex shapes that are symmetrical to each other, their SORI is 110 μm, the in-plane thickness variation (TTV) is 220 μm, and the portion that is 30 mm away from the center point of the front and back surfaces is the thickest. An alumina ceramic transfer master having a thickness of 3000 μm and a diameter of 100 mm was prepared.
As a raw material substrate, a synthetic quartz glass substrate having a diameter of 100 mm, a thickness of 630 μm, a front surface and a back surface SORI of 6 μm, and an in-plane thickness variation (TTV) of 1 μm was prepared in the same manner as in Example 1.
In the same manner as in Example 1, one side of two raw material substrates was simultaneously processed by a double-sided lapping device to obtain a transfer substrate on which the shape of the transfer master was transferred on one side. As for the shape of the obtained transfer substrate, both sides warped 110 μm in a concave shape. Further, the concave thinnest portion was shifted by 30 mm from the center.

The obtained transfer substrate is placed in a double-sided lapping machine, and double-sided lapping is performed in the same manner as in Example 1, and the shape of the master for transfer is also transferred to the surface that has not been transferred in the previous transfer process. A concave lapping substrate having a convex shape of SORI 50 μm and a back surface of SORI 50 μm was obtained.
Further, the surface on the convex side of the obtained lapping substrate is mirror-finished with a single-side polishing apparatus, the mirror surface is convex with SORI 50 μm and BOW is +20 μm, the rough surface is concave with SORI 50 μm and BOW is −20 μm, A synthetic quartz glass substrate having an inner thickness variation (TTV) of 1 μm and a thickness of 500 μm was obtained.
Next, when a polysilicon film was formed on the surface of the obtained synthetic quartz glass substrate by the same method as in Example 1, the film-formed surface was convex with a SORI of 122 μm, and the other surface was concave with a SORI of 122 μm. changed.
Thereafter, a heat treatment at 1100 ° C. was further performed for 2 hours. As a result, the film-formed surface was changed to a convex shape of SORI 4 μm, the other surface was changed to a concave shape of SORI 4 μm, and the thickness variation was 1 μm. A synthetic quartz glass substrate for TFT was obtained.

[Example 6]
As in Example 5, one of the front and back surfaces is flat, the other surface is convexly warped by 110 μm, and the in-plane thickness variation (TTV) is 220 μm. An alumina ceramic transfer master having a thickness of 30 mm from the center point of the back surface and a thickness of 3000 μm and a diameter of 100 mm was prepared.
The same material substrate as that in Example 5 was prepared.
In the same manner as in Example 3, one side of the raw material substrate was processed by a single-sided lapping device to obtain a transfer substrate on which the shape of the master for transfer was transferred on one side. As for the shape of the obtained transfer substrate, one side was flat, and the other side was warped 110 μm in a concave shape. Further, the concave thinnest portion was shifted by 30 mm from the center.
The obtained transfer substrate is placed in a single-sided lapping machine, and single-sided lapping is performed in the same manner as in Example 2, and the shape of the transfer master is transferred to the opposite side of the transfer substrate that was not transferred in the transfer process. Thus, a concave lapping substrate having a convex surface with a SOI of 110 μm and a concave surface of a SOI of 110 μm was obtained.
The surface on the convex side of the obtained lapping substrate is mirror-finished with a single-side polishing apparatus, the mirror surface is convex with SORI 110 μm and BOW is +50 μm, the rough surface is concave with SORI 110 μm and BOW is −50 μm, and the in-plane thickness A synthetic quartz glass substrate having a variation (TTV) of 1 μm and a thickness of 500 μm was obtained.
Next, when a polysilicon film was formed on the surface of the obtained synthetic quartz glass substrate by the same method as in Example 1, the film-formed surface was convex with a SORI of 122 μm, and the other surface was concave with a SORI of 122 μm. changed.
Thereafter, a heat treatment at 1100 ° C. was further performed for 2 hours. As a result, the film-formed surface was changed to a convex shape of SORI 4 μm, the other surface was changed to a concave shape of SORI 4 μm, the in-plane thickness variation was 1 μm, and a substantially flat SORI was obtained. A synthetic quartz glass substrate for polysilicon TFT was obtained.

[Comparative Example 1]
As a transfer master, an alumina ceramic transfer master having a diameter of 100 mm and having a SORI of 110 μm on the front and back, a convex surface on one side, a concave surface on the other surface, a thickness of 2 mm, and a thickness variation of 2 μm is constant. The same raw material substrate as that of Example 1 was prepared.
Using a double-sided lapping machine, the raw material substrate was transferred by the same method as in Example 1 to obtain a transfer substrate having a SORI of 1 μm on the front and back surfaces.
Further, the obtained transfer substrate was made into a double-sided mirror by a double-side polishing apparatus, and the SORI on the front and back surfaces was 1 μm, the BOW on the front surface was +0.5 μm, the BOW on the back surface was −0.5 μm, and in-plane thickness variation (TTV) A synthetic quartz glass substrate having a thickness of 1 μm and a thickness of 500 μm on both sides was obtained.
When a polysilicon film was formed on the resultant synthetic quartz glass substrate in the same manner as in Example 1, the film-formed surface was changed to a convex shape of SORI 120 μm, and the other surface was changed to a concave shape of SORI 120 μm.
After that, when heat treatment at 1050 ° C. was further performed for 1 hour, the in-plane thickness variation (TTV) remained 1 μm, the film-formed surface changed to a convex shape of SORI 60 μm, and the other surface changed to a concave shape of SORI 61 μm. The flat SORI was not obtained.

[Comparative Example 2]
As a master for transfer, for the transfer made of alumina ceramic with SORI of 110 μm on the front and back, convex on one side, concave on the other side, in-plane thickness variation (TTV) 1 μm, thickness 2 mm, diameter 200 mm A master was prepared, and the same material substrate as that of Example 4 was prepared.
After performing a transfer process on the raw material substrate using a single-sided lapping device in the same manner as in Example 4, the obtained transfer substrate was lapped with a double-sided lapping device at a rotation speed of 20 rpm and a load of 100 g / cm ² , A lapping substrate having a SORI of 1 μm was obtained.
Further, the obtained lapping substrate is subjected to double-side polishing, the front and back SORI is 1 μm, the front BOW is +0.5 μm, the back BOW is −0.5 μm, the in-plane thickness variation (TTV) is 1 μm, A synthetic quartz glass substrate having a thickness of 725 μm was obtained.
When a polysilicon film was formed on the resulting synthetic quartz glass substrate in the same manner as in Example 1, the in-plane thickness variation (TTV) remained at 1 μm, and the formed surface had a convex shape of SORI of 120 μm. The surface changed to a concave shape of 120 μm SORI.
After that, when heat treatment at 1050 ° C. was further performed for 1 hour, the in-plane thickness variation (TTV) remained 1 μm, the film-formed surface changed to a convex shape of SORI 60 μm, and the other surface changed to a concave shape of SORI 61 μm. The flat SORI was not obtained.

[Comparative Example 3]
As a transfer master, for the transfer made of alumina ceramic with SORI of 110 μm on the front and back sides, convex on one side, concave on the other side, in-plane thickness variation (TTV) of 1 μm, thickness of 2 mm and diameter of 110 mm A master disk was prepared, and the same material substrate as that of Example 2 was prepared.
After performing a transfer process on the raw material substrate using a double-sided lapping machine in the same manner as in Example 2, transfer so that the flat surface on which the shape of the master for transfer is not transferred faces the top plate side of the single-sided lapping machine A substrate was placed, and lapping was performed under the same conditions as in Example 2 to obtain a lapping substrate having a surface SORI of 1 μm.
Further, one side of the lapping substrate obtained by the single-side polishing apparatus is mirror-finished, the surface SORI is 1 μm, the surface BOW is +0.5 μm, the back BOW is −0.5 μm, and the in-plane thickness variation (TTV) is A synthetic quartz glass substrate having a thickness of 1 μm and a thickness of 500 μm was obtained.
When a polysilicon film was formed on the resultant synthetic quartz glass substrate by the same method as in Example 1, the formed surface was changed to a convex shape of SORI 120 μm, and the other surface was changed to a concave shape of SORI 120 μm.
After that, when heat treatment at 1050 ° C. was further performed for 1 hour, the in-plane thickness variation (TTV) remained 1 μm, the film-formed surface changed to a convex shape of SORI 60 μm, and the other surface changed to a concave shape of SORI 61 μm. The flat SORI was not obtained.

[Comparative Example 4]
As a transfer master, an alumina ceramic transfer master having an SORI of 110 μm on the front and back, a convex on one side, a concave on the other, an in-plane thickness variation (TTV) of 1 μm, a thickness of 2 mm, and a diameter of 200 mm And the same material substrate as that of Example 4 was prepared.
After performing the transfer process of the raw material substrate using the single-sided lapping device in the same manner as in Example 4, transfer the flat surface on which the shape of the transfer master is not transferred to the top plate side of the single-sided lapping device A substrate was placed, and lapping was performed under the same conditions as in Example 2 to obtain a lapping substrate having a surface SORI of 1 μm.
Further, one side of the lapping substrate obtained by the single-side polishing apparatus is mirror-finished, the surface SORI is 1 μm, the surface BOW is +0.5 μm, the back BOW is −0.5 μm, and the in-plane thickness variation (TTV) is A synthetic quartz glass substrate having a thickness of 1 μm and a thickness of 725 μm was obtained.
When a polysilicon film was formed on the resultant synthetic quartz glass substrate in the same manner as in Example 1, the film-formed surface was changed to a convex shape of SORI 120 μm, and the other surface was changed to a concave shape of SORI 120 μm.
After that, when heat treatment at 1050 ° C. was further performed for 1 hour, the thickness variation remained 1 μm, the film-formed surface changed to a convex shape of SORI 60 μm, the other surface changed to a concave shape of SORI 61 μm, and a desired flat SORI was obtained. It was not obtained.

  A summary of the above examples and comparative examples is shown in Table 1.

A Semiconductor substrate 1 Double-sided lapping device 2 Single-sided lapping device 10, 20, 30, 40 Transfer master 11A, 21A Transfer substrate 100, 200, 300, 400 Transfer master surface 110, 210, 310, 410 Transfer master Back surface 100A, 110A, 200A, 210A Center point L1, L2 Center line S1, S2, S3, S4 Virtual plane (surface orthogonal to center line)
11, 21 Raw material substrate

Claims (10)

  A semiconductor substrate comprising one surface having a convex SORI and the other surface having a concave SORI comparable to the SORI and having a thickness variation of 3 μm or less.   The semiconductor substrate according to claim 1, wherein the SORI of each of the surfaces is 50 to 600 μm.   3. The semiconductor substrate according to claim 1, wherein the BOW on one surface having the convex SORI is +25 to +300.   4. The semiconductor substrate according to claim 1, wherein a BOW of the other surface having the concave SORI is −25 to −300.   The semiconductor substrate according to claim 1, wherein the thickness is 0.5 to 3 mm.   The semiconductor substrate according to claim 1, wherein the semiconductor substrate has a circular shape with a diameter of 100 to 450 mm or a rectangular shape with a diagonal length of 100 to 450 mm in plan view.   The semiconductor substrate according to any one of claims 1 to 6, which is made of synthetic quartz glass.   The semiconductor substrate according to claim 1, which is a polysilicon TFT substrate. It has a front surface and a back surface, passes through an intermediate point on the center line connecting the center points of the front and back surfaces, and has a thickness variation such as SORI in which the front surface and the back surface face each other symmetrically with respect to a plane orthogonal to the center line. A preparation process for preparing a master for transfer;
Two raw material substrates are placed in a double-sided lapping machine so as to sandwich the transfer master, and the surface of each raw material substrate that is not in contact with the transfer master is processed to transfer the shape of the transfer master to one side. A transfer process for producing the two transferred substrates;
A wrapping process for producing a lapping substrate by wrapping both surfaces of the transfer substrate or by wrapping only a surface of the transfer substrate in which the shape of the transfer master is not transferred in the transfer step;
A method for producing a semiconductor substrate, comprising polishing both sides or one side of the lapped substrate. It has a front surface and a back surface, passes through an intermediate point on the center line connecting the center points of these front and back surfaces, and either one of the front and back surfaces is parallel to a surface orthogonal to the center line, And a preparatory step of preparing a master for transfer in which the other surface in contact with the raw material substrate of the front and back surfaces is orthogonal to the center line and symmetrical with respect to the center line;
The material substrate is placed on a single-sided lapping machine so as to be in contact with the other surface of the transfer master, and the surface of the material substrate that is not in contact with the transfer master is processed to transfer the shape of the transfer master to one surface. A transfer process for producing a transferred substrate,
A wrapping process for producing a lapping substrate by wrapping both surfaces of the transfer substrate or by wrapping only a surface of the transfer substrate in which the shape of the transfer master is not transferred in the transfer step;
A method for producing a semiconductor substrate, comprising polishing both sides or one side of the lapped substrate.

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