JP2013129023A - Method for manufacturing sapphire substrate, and sapphire substrate - Google Patents

Abstract

A method of manufacturing a sapphire substrate having a surface roughness comparable to the surface roughness of a surface of a sapphire substrate obtained by CMP polishing even if the process cost is reduced, and a sapphire substrate are provided.
A sapphire substrate manufacturing method for manufacturing a sapphire substrate by subjecting a substrate obtained by slicing from a sapphire ingot to a plurality of processes, and wet blasting at least a main surface 10A of the substrate 10. A wet blasting step and a CMP step of CMP polishing the wet blasted main surface 10A are performed after the wet blasting step.
[Selection] Figure 9

Description

  The present invention relates to a method for manufacturing a sapphire substrate and a sapphire substrate.

  Nitride III-V compound semiconductors have been put into practical use as light-emitting devices such as LEDs (Light Emitting Diodes) and electronic devices that make use of features excellent in heat resistance and environmental resistance. This group III-V nitride semiconductor is often grown on a single crystal sapphire substrate, and the sapphire substrate is generally mirror-polished.

  For the manufacture of sapphire substrates, a cutting process for cutting a substrate from a sapphire ingot, a surface attaching process for attaching the surface of the substrate to a ceramic block using wax, and a back surface for lapping the back surface of the substrate supported by the ceramic block A single-sided lapping step, a heat treatment step for reducing processing distortion caused by lapping after removing the ceramic block and the substrate, a backside attaching step for attaching the backside of the substrate to the ceramic block using wax, And a main surface mechanochemical polishing step in which the surface is subjected to CMP (Chemical Mechanical Polishing) (see Patent Document 1).

  In addition, instead of the front surface bonding process and the back surface single-sided lapping process, a double-sided lapping process for lapping both surfaces of the sapphire substrate or a lapping process before the main surface mechanochemical polishing process is performed and rough polishing is performed in advance. This process is also known as the prior art (see FIG. 10).

  The lapping apparatus used in lapping has, for example, a lapping surface plate to which loose abrasive grains having a particle diameter of several μm are supplied, and rotates the lapping surface plate while pressing the substrate against the lapping surface plate. , An apparatus in which the substrate is shaved by the supplied free abrasive grains. Since the particle size of the loose abrasive is larger than the loose abrasive for CMP polishing described later, it is used for rough polishing of the substrate.

  A CMP apparatus used in CMP polishing cleans a polishing table that can be rotated, a polishing pad placed thereon, a polishing head that presses the polishing surface of the substrate against the polishing surface of the polishing pad, and the polishing pad. Therefore, a cleaning liquid supply nozzle for spraying a cleaning liquid, a free abrasive grain supply nozzle for supplying free abrasive grains, and a motor for rotating the polishing table are provided.

  In the main surface mechanochemical polishing step, for example, alkaline colloidal silica having a particle size of several nm is used as the free abrasive grains. This is smaller than the particle size of the loose abrasive used in lapping.

  With such a CMP apparatus, free abrasive grains are dropped on the polishing pad from the free abrasive supply nozzle, the polishing surface of the substrate is pressed against the polishing surface of the polishing pad by the polishing head, and the polishing table and the polishing head are rotated. Thus, the free abrasive grains of the colloidal silica which are alkaline and the substrate are chemically reacted and polished chemically and mechanically. Thus, polishing is performed more precisely than lapping.

JP 2006-347776 A

  In the method for manufacturing a sapphire substrate disclosed in Patent Document 1, when polishing is performed by CMP, foreign matters such as polishing scraps (scraps such as an object to be polished and a polishing pad) and aggregates of free abrasive grains are generated. In order to remove the foreign matter, polishing is performed while spraying the cleaning liquid from the cleaning liquid supply nozzle onto the polishing surface of the polishing pad. Moreover, since the free abrasive grains of alkaline colloidal silica used for CMP polishing are chemicals, a large amount of cleaning liquid is used for cleaning.

  Thereby, the process cost by manufacture of a sapphire substrate has become very high. Recently, due to the increasing demand for cost reduction of semiconductor elements such as LED elements, it is necessary to shorten and reduce processes as much as possible.

  If a sapphire substrate is manufactured only by lapping which is rough polishing without CMP polishing in order to reduce the process cost, the surface roughness which is a value indicating the flatness of the surface of the sapphire substrate deteriorates, and then the semiconductor element When forming, the surface roughness was not sufficient.

  The present invention has been made in view of the above points, and an object of the present invention is to reduce the process cost. Even if the process cost is reduced, the rough surface of the sapphire substrate obtained by CMP polishing is provided. The object is to provide a method for manufacturing a sapphire substrate having a surface roughness of the same degree as that of the sapphire and a sapphire substrate.

  In order to achieve the above object, the present invention is configured as follows.

  A method for manufacturing a sapphire substrate according to the present invention is a method for manufacturing a sapphire substrate by manufacturing a sapphire substrate by subjecting a substrate obtained by slicing from a sapphire ingot to a plurality of steps, and is a method for manufacturing a sapphire substrate. A wet blasting process for wet blasting the surface; and a CMP process for polishing the wet-blasted main surface after the wet blasting process.

  Moreover, the sapphire substrate which concerns on this invention is a sapphire substrate manufactured by said manufacturing method of a sapphire substrate.

  By such specific matters, the surface roughness of the sapphire substrate before the CMP process is improved by wet blasting, and the processing time of the CMP process can be shortened, so that a large amount of cleaning liquid is not used and the manufacturing cost is reduced. A sapphire substrate having a surface roughness equivalent to that of the CMP process can be manufactured.

  In the method for manufacturing the sapphire substrate, the polishing amount of the substrate in the CMP step is 10 μm or less.

  Due to such specific matters, since the polishing in the CMP process is 10 μm or less, the processing time can be shortened compared with the normal CMP process, so that a large amount of cleaning liquid is not used and the manufacturing cost can be reduced. In addition, a sapphire substrate having a surface roughness equivalent to that of the CMP process can be manufactured.

  In the method for manufacturing the sapphire substrate, the wet blast nozzle used in the wet blasting step is arranged at an angle smaller than 90 ° with the substrate.

  With such a specific matter, the surface roughness of the sapphire substrate can be improved more than when the angle between the wet blast nozzle and the substrate is 90 °.

In the above-described sapphire substrate, the surface roughness in the range of 0.04 .mu.m ² of 4 [mu] m ² of the sapphire substrate after the CMP step, and it is 0.3nm or less than 0.01 nm.

With such a specific matter, a sapphire substrate having the same surface roughness as when the sapphire substrate is polished only by the CMP step without performing the wet blasting step can be obtained, and within the above surface roughness range. If so, it is assumed that the semiconductor element is formed on the sapphire substrate, which enables high-quality crystal growth by metal organic vapor phase epitaxy performed at the time of forming the semiconductor element in the subsequent step.

  With such a specific matter, the processing time of the CMP process can be shortened, so that a sapphire substrate having a semiconductor element formed on the surface of a sapphire substrate with low manufacturing cost and excellent surface roughness is obtained.

  According to the present invention, a process cost can be reduced, and a method for manufacturing a sapphire substrate having a surface roughness comparable to that of a sapphire substrate obtained by CMP polishing even if the process cost is reduced, and sapphire A substrate can be provided.

The double-sided lapping process of the manufacturing method of the sapphire substrate which concerns on this invention is shown, (a) is the schematic of a double-sided lapping apparatus, (b) is sectional drawing which shows a double-sided lapping process. It is a schematic diagram which shows the wet blasting process of the manufacturing method of the sapphire substrate which concerns on this invention. It is sectional drawing which shows the sticking process of the manufacturing method of the sapphire substrate which concerns on this invention. The lapping process of the manufacturing method of the sapphire substrate which concerns on this invention is shown, (a) is a top view which shows a lapping apparatus, (b) is sectional drawing which shows a lapping process. The CMP process of the manufacturing method of the sapphire substrate which concerns on this invention is shown, (a) is a top view which shows a CMP apparatus, (b) is sectional drawing which shows a CMP process. It is a manufacturing method of a sapphire substrate concerning the present invention, Comprising: It is an AFM image of a sapphire substrate in case CMP polish amount is 3 micrometers, (a) is an AFM image of a sapphire substrate which performed a wet blast process, (b) is It is an AFM image of the sapphire substrate which does not perform a wet blast process. It is a manufacturing method of a sapphire substrate concerning the present invention, Comprising: It is an AFM image of a sapphire substrate in case CMP polish amount is 10 micrometers, (a) is an AFM image of a sapphire substrate which performed a wet blast process, (b) is It is an AFM image of the sapphire substrate which does not perform a wet blast process. It is a graph which shows the surface roughness of the sapphire substrate manufactured with the manufacturing method of the sapphire substrate which concerns on this invention, Comprising: (a) is a graph which shows the comparison of the surface roughness by the presence or absence of a wet blast process, (b), It is a graph which shows the relationship between the angle of the wet blast nozzle of a wet blast process, and the surface roughness of a sapphire substrate. It is a manufacturing flow of the manufacturing method of the sapphire substrate which concerns on this invention. It is a manufacturing flow of the manufacturing method of the conventional sapphire substrate.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 9 is a manufacturing flow of the method for manufacturing a sapphire substrate according to the present invention.

  The method for manufacturing a sapphire substrate according to the present embodiment includes a double-sided lapping process for lapping both surfaces of a substrate 10 sliced from a sapphire ingot, a wet blasting process for processing the surface of the substrate 10 with a wet blasting apparatus, and a double-sided lapping process. And an annealing step for relaxing processing stress and processing distortion generated by the wet blasting step, an attaching step for attaching the substrate 10 to the substrate holding member 300, a lapping step for rough polishing the surface 10A of the substrate 10, and lapping. This includes a CMP process for polishing the surface 10A of the substrate 10 and a cleaning process for cleaning the substrate 10.

  A method of manufacturing a sapphire substrate will be described along this process. In addition, all of the embodiments described below are examples embodying the present invention, and are not of a nature that limits the technical scope of the present invention.

[Double-sided lapping process]
First, the double-sided lapping process will be described. FIG. 1: shows the double-sided lapping process of the manufacturing method of the sapphire substrate which concerns on this invention, (a) is the schematic of a double-sided lapping apparatus, (b) is sectional drawing which shows a double-sided lapping process.

  In the double-sided lapping process, both sides of the 1.2 mm thick substrate 10 sliced from the sapphire ingot are double-sided lapped.

  The double-sided lapping apparatus 200 used for double-sided lapping includes a jig 210 that accommodates the substrate 10, an upper surface plate 220 provided on the upper side of the jig 210, and a lower surface plate 221 provided on the lower side of the jig 210. And a motor (not shown) that rotates independently with the center of the jig 210 as the rotation axis, the center of the upper surface plate as the rotation axis, and the center of the lower surface plate as the rotation axis. A copper surface plate is used for the upper surface plate 220 and the lower surface plate 221 of this embodiment.

  The jig 210 is provided with a through hole 211 larger than the diameter of the substrate 10. The substrate 10 is accommodated in the through hole 211. In the present embodiment, four substrates 10 are accommodated in a jig 210 (see FIG. 1A).

  After the substrate 10 is accommodated in the jig 210, the jig 210 and the substrate 10 are placed on the lower surface plate 221. Then, the upper surface plate 220 is lowered toward the lower surface plate 221, and the substrate 10 is sandwiched between the upper surface plate 220 and the lower surface plate 221. When the upper surface plate 220 is weighted, the substrate 10 is pressed against the lower surface plate 221. Here, since the thickness of the jig 210 is designed to be thinner than the thickness of the substrate 10, both surfaces of the substrate 10 are in contact with the upper surface plate 220 and the lower surface plate 221 respectively (see FIG. 1B). .

  In a state where the substrate 10 is sandwiched between the upper surface plate 220 and the lower surface plate 221, the upper surface plate 220 and the lower surface plate 221 rotate so as to be opposite to each other, and the upper surface plate 220, the lower surface plate 221 and the substrate 10 are rotated. Pour loose abrasive in between. Thereby, both surfaces of the substrate 10 are lapped by the free abrasive grains. Here, since the jig 210 also rotates with the center of the jig 210 as a rotation axis, lapping is performed so that the surface roughness of the four substrates housed in the jig is equal.

  The loose abrasive grains have a particle size of several tens of μm to several hundreds of μm. For example, loose abrasive grains such as boron carbide or green carbide are used.

  As a result, the thickness of the substrate 10 is adjusted to 0.25 mm to make both surfaces, and the surface roughness of both surfaces of the substrate 10 is in the range of several tens nm to several hundred μm.

  This step is not limited to double-sided lapping, and single-sided lapping or wire sawing may be used.

[Wet blasting process]
Next, the wet blast process will be described. FIG. 2 is a schematic diagram showing a wet blasting process of the method for manufacturing a sapphire substrate according to the present invention.

  In the wet blasting process, the surface of the sapphire substrate (surface to be polished by CMP described later) is wet blasted.

  A wet blasting apparatus 500 used for wet blasting is disposed so as to face a stage 510 on which a substrate 10 is placed, a stage moving mechanism (not shown) that moves the stage 510 in one direction, and the stage 510. A wet blast nozzle 520 for spraying loose abrasive grains 530 in which loose abrasive grains and compressed air are mixed is provided on 510.

  The wet blast nozzle 520 includes a free abrasive grain introduction part 521 into which free abrasive grains are introduced, an air introduction part 522 into which compressed air is introduced, and a mixing chamber in which the introduced free abrasive grains and compressed air are mixed. 523 and a slit-like injection unit 524 that injects the free abrasive grains 530 sent together with the compressed air from the mixing chamber 523 onto a straight line orthogonal to the moving direction of the stage 510 in the same plane as the stage 510. It has been.

  In the present embodiment, the wet blast nozzle 520 is disposed at an angle of 45 ° with the substrate 10.

  The substrate 10 is placed on the stage 510 so that the surface 10A of the substrate 10 is wet-blasted, and the stage 510 is moved at a speed of 1 mm / sec by the stage moving mechanism, and the wet blast nozzle 520 is set to 0. The loose abrasive grains 530 are sprayed toward the substrate 10 at a pressure of 4 MPa. As a result of the movement of the stage 510 on which the substrate 10 is placed, the free abrasive grains 530 are sprayed onto the entire surface 10A of the substrate 10, so that the entire surface 10A of the substrate 10 is wet blasted.

  In the wet blast processing, the processing rate is set to a speed of 1.5 μm / min, and the thickness of the substrate 10 is processed to 3 μm. That is, the wet blasting time for the surface 10A of the substrate 10 is 2 minutes.

  The processing rate of wet blast processing depends on the moving speed of the stage 510. That is, the slower the moving speed of the stage 510, the longer the time during which the substrate 10 is exposed to the loose abrasive grains 530, and the greater the processing amount. Conversely, the faster the moving speed of the stage 510, the shorter the time during which the substrate 10 is exposed to the loose abrasive grains 530, and the smaller the processing amount.

  Here, the free abrasive grains used for the free abrasive grains 530 are desirably free abrasive grains having a uniform particle diameter in order to improve the flatness of the substrate 10, and alumina having an average particle diameter of 100 μm is used. .

  In addition, although the wafer size of the substrate 10 of the present embodiment is assumed to be 4 inches, the 6-inch substrate 10 can be wet-blasted using a 6-inch stage. By manufacturing a 6-inch sapphire substrate, more semiconductor elements can be formed on the surface of the sapphire substrate than on a 4-inch sapphire substrate, so that the amount of collected semiconductor elements increases. Therefore, the manufacturing cost can be reduced.

[Annealing process]
Next, the annealing process will be described.

  In the annealing process, the processing stress and the processing distortion generated in the substrate 10 by the double-sided lapping process and the wet blasting process are alleviated. Specifically, the substrate 10 is placed in a high temperature furnace (not shown) and held at a heating temperature of 1600 ° C. for 3 hours.

  Thereby, the processing stress and processing distortion of the substrate 10 can be relaxed.

  Here, the annealing temperature and annealing time are merely examples, and are not limited to the above temperature and time.

[Pasting process]
Next, the attaching process will be described. FIG. 3 is a cross-sectional view showing the attaching process of the method for manufacturing a sapphire substrate according to the present invention.

  In the attaching step, the substrate holding member 300 is attached to the surface opposite to the surface of the substrate 10 to be lapped in the lapping step described later (in this embodiment, the back surface 10B of the substrate 10).

  The substrate holding member 300 includes a plate 310, a holding member 320 that is fixed on the plate 310 and has an opening, and a suction pad 330 that is accommodated in the opening of the holding member 320 and attached to the plate 310.

  The suction pad 330 is attached to the back surface 10B of the substrate 10, and the holding member 320 and the back surface 10B of the substrate 10 are attached to the back surface 10B of the substrate 10 using wax as an adhesive. At the time of pasting, pressure is applied from the surface 10A of the substrate 10 for pasting.

  Therefore, the substrate 10 and the plate 310 are attached, and the substrate 10 and the substrate holding member 300 are attached. Note that an acrylic resin or a glass epoxy resin may be used as the adhesive. The plate 310 is a ceramic plate.

  Thereby, when the substrate 10 is lapped in a lapping process described later, the substrate holding member 300 is attached to the back surface 10B of the substrate 10, so that the substrate 10 is protected even if the substrate 10 is loaded. Can do.

[Lapping process]
Next, the lapping process will be described. 4A and 4B show a lapping process of the method for manufacturing a sapphire substrate according to the present invention, wherein FIG. 4A is a plan view showing a lapping apparatus, and FIG. 4B is a cross-sectional view showing the lapping process.

  In the lapping step, lapping is performed on the substrate 10 side (surface 10A of the substrate 10) to which the substrate holding member 300 described above is attached.

  The lapping apparatus 400 used in the lapping process discharges a surface plate 410 for lapping the substrate 10, a fixture 420 to which the substrate 10 is attached so as to face the surface plate 410, and free abrasive grains used during lapping. And a motor (not shown) that rotates independently with the center of the fixture 420 as the rotation axis and the center of the surface plate 410 as the rotation axis.

  As the surface plate 410 of this embodiment, a relatively soft metal-based surface plate containing copper or tin is used.

  After attaching the substrate 10 to which the substrate holding member 300 described above is attached to the fixture 420, the fixture 420 is loaded in the direction of the surface plate 410, whereby the surface 10A of the substrate 10 is pressed against the surface plate 410. .

  In this state, the surface plate 410 and the fixture 420 are rotated so as to be opposite to each other, and free abrasive grains are discharged from the nozzle 430. The platen 410 is preferably rotated at a rotational speed from 30 rpm to 80 rpm.

  The loose abrasive has a particle size of several μm, and for example, diamond slurry is used.

  Thereafter, the surface 10A of the substrate 10 is polished with a polishing cloth such as soft foamed urethane or a suede pad using silica particles having a particle diameter of several tens of nm.

[CMP process and precision cleaning process]
Next, the CMP process will be described. 5A and 5B show a lapping process of the method for manufacturing a sapphire substrate according to the present invention. FIG. 5A is a plan view showing a CMP apparatus, and FIG. 5B is a cross-sectional view showing the CMP process.

  In the CMP process, after performing the lapping described above, the surface 10A of the substrate 10 on which lapping has been performed is subjected to CMP polishing.

  The CMP apparatus 450 used in the CMP process and the lapping apparatus 400 described above are provided with a cleaning liquid nozzle 460 for discharging a cleaning liquid for precisely cleaning chemicals such as free abrasive grains, and free abrasive grains. The only difference is the use of colloidal silica having a particle size of several tens of nanometers. Therefore, only the differences will be described below, and the same components are denoted by the same reference numerals and the description thereof is omitted. To do.

  In the CMP polishing, the surface plate 410 and the mounting tool 420 are rotated by the rotation shaft of the surface plate 410 and the rotation shaft of the mounting tool 420, and free abrasive grains are discharged from the nozzle 430 to perform the CMP polishing. After that, the cleaning nozzle is used to remove foreign substances such as polishing scraps (scraps such as workpieces and polishing pads) and aggregates of loose abrasive grains, and cleaning colloidal silica, which is an alkaline chemical. While discharging from 460, the surface 10A of the substrate 10 is precisely cleaned.

[Surface roughness of sapphire substrate]
The surface roughness of the surface 10A of the substrate 10 after the CMP process will be described with reference to FIGS.

  FIG. 6 is a method for manufacturing a sapphire substrate according to the present invention, which is an AFM image of a sapphire substrate when the CMP polishing amount is 3 μm, (a) is an AFM image of a sapphire substrate that has been subjected to a wet blasting process, (B) is an AFM image of a sapphire substrate not subjected to wet blasting, and FIG. 7 is a method for manufacturing a sapphire substrate according to the present invention, and is an AFM image of a sapphire substrate when the CMP polishing amount is 10 μm. FIG. 8A is an AFM image of a sapphire substrate that has been wet-blasted, FIG. 8B is an AFM image of a sapphire substrate that has not been wet-blasted, and FIG. It is a graph which shows the surface roughness of the sapphire substrate manufactured by the method, (a) is a comparison of surface roughness with and without wet blasting process The graph shown, (b) is a graph showing the relationship between the angle of the wet blast nozzle and the surface roughness in the wet blast process.

  First, the difference in surface roughness due to the presence or absence of the wet blasting process will be described with reference to the graph of FIG.

  The graph shown in FIG. 8A is a graph obtained by measuring the surface roughness of the sapphire substrate after the manufacturing process of the series of sapphire substrate manufacturing methods described above, and the vertical axis indicates the surface roughness and the horizontal axis. In addition, the CMP polishing amount is used.

When the CMP polishing amount is 3 μm, the surface roughness of the substrate 10 is 0.3 nm in the range of 4 μm ² when the wet blasting process is present (see FIG. 6A). On the other hand, when there was no wet-blasting process, the surface roughness of the substrate 10 was 3.2 nm in the range of 4 μm ² (see FIG. 6B).

  Therefore, the result that the surface roughness of the board | substrate 10 which performed the wet blast process was excellent was obtained, and the result that the wet blast process was effective in the improvement of the surface roughness of the board | substrate 10 was obtained.

  Further, when the change in surface roughness when the CMP polishing amount is increased from 3 μm (lapping 10 μm) to 10 μm (lapping 40 μm) with and without the wet blasting process, when there is no wet blasting process, The surface roughness is improved in proportion to the polishing amount. On the other hand, when there is a wet blasting process, even when the CMP polishing amount is increased, the surface roughness does not change so much (see FIG. 8A).

Accordingly, even when the polishing amount is as small as 3 μm (lapping amount: 10 μm), the surface roughness is 0.3 nm within the range of 4 μm ² (see FIG. 6A), and the CMP is performed without performing the wet blasting process. A surface roughness equivalent to 0.3 nm (FIG. 7B), which is the value of the surface roughness of the sapphire substrate when the polishing amount is 10 μm (lapping 40 μm), was obtained. That is, even if the amount of CMP polishing of the substrate 10 is small, a sapphire substrate with good surface roughness can be manufactured by performing the wet blasting process.

  Next, the difference in surface roughness of the sapphire substrate depending on the angle of the wet blast nozzle with respect to the sapphire substrate in the wet blasting process will be described with reference to the graph of FIG.

  The graph shown in FIG. 8B is a graph obtained by measuring the surface roughness of the sapphire substrate after the manufacturing process of the series of manufacturing methods of the sapphire substrate described above. The angle between the wet blast nozzle and the sapphire substrate during the wet blast process is set on the shaft.

  In the present embodiment, the surface roughness of the sapphire substrate when the angle formed by the wet blast nozzle 520 and the substrate 10 is 45 ° and the surface roughness of the sapphire substrate when 90 ° are obtained. Plotting.

The surface roughness when the angle between the wet blast nozzle 520 and the substrate 10 is 90 ° (that is, when the substrate 10 is arranged directly below the wet blast nozzle 520 and the free abrasive grains 530 are injected vertically) is It was 0.80 nm in the range of 4 μm ² .

On the other hand, the surface roughness of the substrate 10 in the case where the wet blast nozzle 520 was laid at an angle of about 45 ° and the free abrasive grains 530 were sprayed was 0.12 nm in the range of 4 μm ² from the experiment.

  From this, it was found that the surface roughness of the substrate 10 was superior when the angle formed by the wet blast nozzle 520 and the substrate 10 was 45 °. That is, the surface roughness of the sapphire substrate can be improved by setting the angle between the wet blast nozzle 520 and the substrate 10 to be less than 90 °.

  Furthermore, semiconductor elements such as LEDs and power devices can be formed on the substrate 10 having excellent surface roughness.

10 Substrate 10A Main surface 450 CMP apparatus 500 Wet blast apparatus 520 Wet blast nozzle

Claims (6)

A sapphire substrate manufacturing method for manufacturing a sapphire substrate by performing processing over a plurality of steps on a substrate obtained by slicing from a sapphire ingot,
A wet blasting process for wet blasting at least the main surface of the substrate;
After the wet blast process, a CMP process for CMP polishing the wet-blasted main surface;
A method for manufacturing a sapphire substrate, comprising: A method for producing a sapphire substrate according to claim 1,
The method for manufacturing a sapphire substrate, wherein the polishing amount of the substrate in the CMP step is 10 μm or less. It is a manufacturing method of the sapphire substrate according to claim 1 or 2,
The method for manufacturing a sapphire substrate, wherein the wet blast nozzle used in the wet blasting step is arranged at an angle smaller than 90 ° with the substrate.   A sapphire substrate manufactured by the method for manufacturing a sapphire substrate according to any one of claims 1 to 3. The sapphire substrate according to claim 4,
The sapphire substrate having a surface roughness in a range of 0.04 μm ² to 4 μm ² of the sapphire substrate after the CMP step is 0.01 nm or more and 0.3 nm or less. A sapphire substrate according to claim 4 or 5,
A sapphire substrate, wherein a semiconductor element is formed on the sapphire substrate.