JPH11121310A - Manufacture of semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the manufacturing efficiency of a semiconductor substrate and, accordingly, to reduce the manufacturing cost of the substrate. SOLUTION: A method for manufacturing semiconductor device includes (a) a preparatory process for flattening (specular finishing) both of the front and rear surfaces of a single-crystal silicon wafer 11, (b) a protective film forming process for forming a contamination protective film 12 on the entire surface of the wafer 11, and (c) a first ion implanting process for forming a first ion-implanted layer 13 which is distributed in parallel with one surface of the wafer 11 in the wafer 11. The method also includes (d) a second ion implanting process for forming a second ion-implanted layer 14 distributed in parallel with the other surface of the wafer 11 in the wafer 11, (e) a protective film removing process for removing the contamination protective film 12, and (f) an insulating film forming process for respectively forming insulating films 15a and 16a on the whole surfaces of two base substrates 15 and 16. Then (g) a stripping-off process is performed for stripping off the silicon wafer 11 at the parts of the ion-implanted layers 13 and 14 after conducting a sticking process for respectively sticking the base substrates 15 and 16 to both of the front and rear surfaces of the wafer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a base substrate,
The present invention relates to a method for manufacturing a semiconductor substrate provided with a semiconductor layer for element formation while being electrically insulated from the base substrate.

[0002]

2. Description of the Related Art As a semiconductor substrate of this kind, for example,
SO in which a single crystal silicon thin film is provided as a semiconductor layer
There is an I (Silicon On Insulator) substrate. This has a structure in which an insulating oxide film is formed on a silicon substrate and a single-crystal silicon thin film is formed on the oxide film. By using such a semiconductor substrate, insulation separation from the substrate is achieved. It is not necessary to perform a separate process, and the element can be formed on a single-crystal silicon thin film with a high degree of integration and a high degree of integration to form an integrated circuit.

[0003] As a method of manufacturing a single-crystal silicon thin film for such an SOI structure, various methods have conventionally been adopted. Among them, the following three steps are used. Semiconductor thin film manufacturing technology
No. 211128. Hereinafter, the manufacturing method will be described with reference to FIG.

First, as a first step, a hydrogen gas or a rare gas is ion-implanted into a single crystal silicon wafer 1 as a semiconductor substrate material from one surface thereof.
An ion implanted layer 2 in which implanted ions are distributed at a predetermined depth in the single crystal silicon wafer 1 is formed (see FIG. 5A). Next, as a second step, a base substrate 3 made of at least one rigid material is bonded to the surface of the single crystal silicon wafer 1 on the ion implantation side by a bonding method or the like (see FIG. 5B). In this case, a silicon wafer covered with the insulating film 4 is used as the base substrate 3.

Further, as a third step, a single crystal silicon wafer 1 and one object of the base substrate 3 are subjected to a heat treatment, so that a single void is formed at a boundary between microvoids (microbubbles) formed in the ion implantation layer 2. The crystalline silicon wafer 1 is separated from the thin film portion so as to be separated, and the base substrate 3
An SOI substrate 6 having a structure in which a single crystal silicon thin film 5 is bonded thereon via an insulating film 4 or the like is formed thereon (see FIG. 5C). In this case, in order to increase the bonding strength between the insulating film 4 and the single-crystal silicon thin film 5, actually, it is desirable to perform a heat treatment at a temperature higher than the heat treatment temperature for the above-described separation for a predetermined time or more. In practice, a step of flattening the peeled surface by chemical mechanical polishing or the like may be necessary.

[0006]

In the above-mentioned conventional configuration, 1
A heat treatment that requires a relatively long time must be performed each time one SOI substrate 6 is manufactured, and the manufacturing efficiency is deteriorated. This is an unsolved problem in reducing the manufacturing cost. Had become.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a semiconductor substrate capable of realizing an improvement in manufacturing efficiency and a reduction in manufacturing cost associated therewith. It is in.

[0008]

In order to achieve the above object, a manufacturing method as described in claim 1 can be adopted.
According to this manufacturing method, the semiconductor substrate material (11) includes:
In accordance with the execution of the first ion implantation step and the second ion implantation step, the first ion implantation layer (13) and the second ion implantation layer (14,
14 ') is formed. Thereafter, the base substrates (15, 16) are bonded to both surfaces of the semiconductor substrate material (11) in accordance with the execution of the bonding step.

In the peeling step, the semiconductor substrate material (11) and the two base substrates (1) as described above are used.
By subjecting the integrated body of (5, 16) to heat treatment, the semiconductor substrate material (11) is formed by the first ion-implanted layer (13) and the second ion-implanted layer (14, 14 '). It comes off at the defective layer portion to be formed. As a result, the base substrate (15,
16) On the semiconductor layer (1) electrically insulated therefrom
1a, 11b) and two semiconductor substrates (17,
18) is manufactured, and these semiconductor substrates (17,
The semiconductor substrate material (11 ') in a state where the two semiconductor layers (11a, 11b) for (18) are peeled off remains.

As described above, two semiconductor substrates (17, 18) can be manufactured by one heat treatment, and as a result, the manufacturing efficiency is improved. As a result, the time required for manufacturing is reduced (that is, the throughput is improved). ), The production cost can be reduced. Further, the semiconductor substrate material (11 ') after the two semiconductor layers (11a, 11b) have been peeled off can be reused, which also contributes to a reduction in manufacturing cost. become able to.

According to the manufacturing method of the present invention, following the peeling step, the bonding strength of the bonding surface between the base substrate (15, 16) and the semiconductor layer (11a, 11b) is increased. As a result of the heat treatment step, the reliability of the finally manufactured semiconductor substrates (17, 18) can be improved. In this case as well, the bonding strength of the bonding surfaces of the two semiconductor substrates (17, 18) can be simultaneously improved by one heat treatment step subsequent to the heat treatment in the peeling step. Improvements can be realized.

According to the manufacturing method described in claim 3, the first ion implantation step for forming the first ion implantation layer (13) is performed from one surface side of the semiconductor substrate material (11). Since the second ion implantation step for forming the second ion implantation layer (14) is performed from the other surface side of the semiconductor substrate material (11), the first ion implantation layer (13) and the second ion implantation step are formed. (2) The depth position of the ion implantation layer (14) can be strictly set, and the thickness dimension of the semiconductor layers (11a, 11b) of the finally obtained semiconductor substrate can be easily controlled. Become. In addition, the first and second
If the ion implantation conditions in the ion implantation step are exactly the same, the two semiconductor substrates (17,
The characteristics of 18) can be matched, and this is a manufacturing method suitable for manufacturing products having the same standard.

According to the manufacturing method of the present invention, the first ion implantation step for forming the first ion implantation layer (13) and the first ion implantation step for forming the second ion implantation layer (14 ') are performed. In the second ion implantation step, the ion implantation may be performed from the same surface side of the semiconductor substrate material (11), so that the semiconductor substrate material (11) does not need to be turned over at the time of ion implantation, and the manufacturing process is correspondingly simplified. can do.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 and 2 are schematic cross-sectional views showing a manufacturing process of an SOI substrate.

That is, in the preparation step shown in FIG. 1A, for example, both sides of a single crystal silicon wafer 11 (corresponding to a semiconductor substrate material in the present invention) are subjected to chemical mechanical polishing (CMP).
(Mirror surface). In this case, when a commercially available single-side polished type wafer is used as the single-crystal silicon wafer 11, only the non-polished surface (back surface) is subjected to chemical mechanical polishing.

In the protective film forming step, as shown in FIG. 1B, a single crystal silicon wafer 11 is thermally oxidized to form a contaminant protective film 12 made of a silicon oxide film having a uniform thickness over the entire surface. Form. In addition, this contamination protection film 12
Is to prevent the single crystal silicon wafer 11 from being contaminated by heavy metal or the like in an ion implantation step described later, and the film thickness thereof is preferably 50 to 100.
It is set to about nm. Further, instead of the above-described thermal oxidation method, a deposition method such as a CVD method or a PVD method is used.
It is also possible to form a contamination protection film made of a silicon oxide film on both the front and back surfaces of the single crystal silicon wafer 11.

Thereafter, in a first ion implantation step shown in FIG. 1C, hydrogen ions or rare gas ions are implanted from one surface side of the single crystal silicon wafer 11, as indicated by arrows in the figure. Thereby, the first ion-implanted layer 1 in a distribution state parallel to one surface of the single-crystal silicon wafer 11 is provided.
Form 3

Further, in a second ion implantation step shown in FIG. 1D, hydrogen ions or rare gas ions are implanted from the other surface of the single crystal silicon wafer 11 as indicated by arrows in the figure. Thereby, the second ion-implanted layer 14 having a distribution state parallel to the other surface of the single-crystal silicon wafer 11 is formed.

In this case, the dose in the first ion implantation step and the second ion implantation step as described above is 1 × 10 ¹⁶ atoms / cm ² or more, preferably 5 × 10 ¹⁶ atoms / cm ^{2 in} the case of hydrogen ions. Set to ¹⁶ atoms / cm ² or more. In addition, the ion implantation energy is set according to the depth at which the first ion implantation layer 13 and the second ion implantation layer 14 are formed. In this embodiment, the ion implantation conditions in each ion implantation step are set. Set to the same state. It is conceivable to use various ions such as oxygen, chlorine, and fluorine in addition to the above-described hydrogen and the rare gas as the implanted ions.

In the protective film removing step shown in FIG. 1E, the contamination protective film 12 on the single crystal silicon wafer 11 is removed by chemical etching using, for example, a hydrofluoric acid aqueous solution while leaving all or a part thereof. 1 (e) shows a state in which all of them have been removed). The removal of the contamination protective film 12 on both the front and back surfaces of the single crystal silicon wafer 11 can be performed by mechanical polishing or dry etching.

On the other hand, in the insulating film forming step shown in FIG. 1F, two base substrates 15 and 16 made of, for example, a single crystal silicon wafer are prepared, and these base substrates 15 and 16 are thermally oxidized. Insulating films 15a and 16a made of a silicon oxide film having a uniform thickness are formed on the entire surface. The insulating films 15a and 16a become buried oxide films when the SOI structure is finally formed, and the thickness thereof is a value (for example, about 100 to 1000 nm) according to the design shape of the SOI substrate. Is set to Also,
Instead of the above-described thermal oxidation method, an insulating film made of a silicon oxide film is formed on one surface of each of the base substrates 15 and 16 (a surface to be a bonding surface described later) by a deposition method such as a CVD method or a PVD method. It is also possible to form a film.

Thereafter, a bonding step as shown in FIG. 1 (g) is performed. In this bonding step, first, a hydrophilic treatment is performed to impart hydrophilicity to both the front and back surfaces of the single crystal silicon wafer 11 and one surface (bonded surface) of the base substrates 15 and 16.

Specifically, during the hydrophilization treatment, the single crystal silicon wafer 11, the base substrates 15 and 16 are mixed with sulfuric acid and hydrogen peroxide kept at a predetermined temperature (for example, about 90 to 120 ° C.). Solution (H2 SO4: H2 O2 =
By immersing the substrate in an acidic solution such as 4: 1), the entire surface of the single crystal silicon wafer 11 and the base substrates 15 and 16 (the surfaces of the insulating films 15a and 16a) has a very small thickness (for example, at the molecular film level). Is formed to have a hydrophilic property by forming a natural oxide film (not shown). Next, while washing with running water with ultrapure water and drying with a spin dryer or the like, the single-crystal silicon wafer 11 and the base substrate 15 are dried.
And the amount of moisture adsorbed on the surfaces of the two.

Thereafter, the surfaces of the base substrates 15 and 16 are brought into close contact with the front and back surfaces of the single crystal silicon wafer 11, respectively. As a result, the single crystal silicon wafer 11 and the base substrates 15 and 16 are bonded to each other by a hydrogen bond between silanol groups and water molecules on the hydrophilized surface (FIG. 1).
(G)).

Thereafter, in the peeling step shown in FIG.
Single crystal silicon wafer 11 and base substrates 15 and 1
6 is subjected to a heat treatment in an atmosphere of an inert gas such as nitrogen, so that the single crystal silicon wafer 11 is converted into the first ion implantation layer 13 and the second ion implantation layer 1.
4, the single-crystal silicon thin film 11a (corresponding to the semiconductor layer in the present invention) is laminated on the base substrate 15 via the insulating film 15a. In addition to the SOI structure in which the single crystal silicon thin film 11b (corresponding to the semiconductor layer in the present invention) is laminated on the base substrate 16 and the insulating film 16a via the insulating film 16a, The single crystal silicon wafer 11 'in a state where the silicon thin films 11a and 11b are peeled off remains. The defect layer is formed at the maximum distribution depth of the implanted ions.

In this case, specifically, when the first ion-implanted layer 13 and the second ion-implanted layer 14 are formed by hydrogen ions, heat treatment may be performed at about 400 to 600 ° C. Preferably, in response to such a heat treatment,
At the defect layer region formed by the ion-implanted layers 13 and 14, the microbubbles are aggregated to generate macro bubbles, thereby causing separation at the defect layer region as a boundary.

After the single-crystal silicon thin films 11a and 11b are separated from the single-crystal silicon wafer 11 in this separation step, a heat treatment step is performed subsequently, although not specifically shown. In this heat treatment step, the temperature is higher than the heat treatment temperature in the peeling step (1000 ° C. or higher, preferably 1100 ° C. to 1200 ° C.) in an atmosphere of an inert gas such as nitrogen.
℃) or more for a predetermined time (for example, 1 hour or more)
By applying, the bonding strength of the bonding surface between the insulating film 15a (buried oxide film) on the base substrate 15 side and the single-crystal silicon thin film 11a, and the insulating film 16a on the base substrate 16 side
The bonding strength of the bonding surface between the (buried oxide film) and the single-crystal silicon thin film 11b is enhanced.

Further, the single-crystal silicon thin film 1 as described above
On each of the peeled surfaces 1a and 11b, a defect layer formed by the ion implantation remains and a minute step of about several nm to several tens nm is generated. Therefore, in the present embodiment, a flattening step (see FIG. 2 (i)) of removing the defect layer and the minute step on the single-crystal silicon thin films 11a and 11b by chemically mechanically polishing the peeled surface is performed. It is configured to execute.

According to the execution of such a flattening step, finally, two SOI substrates 17 as shown in FIG.
And 18 (corresponding to a semiconductor substrate in the present invention), that is, an SOI substrate 1 in which a single crystal silicon thin film 11a for element formation is provided on a base substrate 15 via an insulating film 15a.
7 and an S-type substrate in which an element forming single-crystal silicon thin film 11b is provided on a base substrate 16 via an insulating film 16a.
The OI substrate 18 is completed. However, the above-described flattening step may be performed as needed.

On the other hand, the single crystal silicon wafer 11 'from which the single crystal silicon thin films 11a and 11b have been peeled off through the peeling step is used again for manufacturing other SOI substrates 17 and 18. For this reason, as shown in FIG. 2 (j), by performing a regeneration step of chemically and mechanically polishing the peeled surface (both front and back surfaces) of the single crystal silicon wafer 11 ', the defect layer remaining on the peeled surface and A configuration in which both the front and back surfaces are flattened (mirror finished) by removing a minute step, and the above-described protection film forming step (see FIG. 1B) and subsequent steps are performed using such a single crystal silicon wafer 11 '. And

According to the above-described embodiment, one heat treatment is performed in the peeling step, and a heat treatment step following the heat treatment is performed only once.
And 18 can be manufactured. As a result, the manufacturing efficiency of the SOI substrates 17 and 18 is improved, and the overall manufacturing cost can be reduced in accordance with the reduction of the required manufacturing time (that is, the improvement of the throughput).

As described above, after the peeling step is performed, a heat treatment step at a temperature higher than the heat treatment temperature in the peeling step is performed, thereby bonding the bonded surface between the single-crystal silicon thin film 11a and the insulating film 15a. The strength and the bonding strength of the bonding surface between the single crystal silicon thin film 11b and the insulating film 16a are increased. Accordingly, the bonding strength between the single-crystal silicon thin film 11a and the insulating film 15a in the finally obtained SOI substrate 17 and the bonding strength between the single-crystal silicon thin film 11b and the insulating film 16a in the SOI substrate 18 are also increased. Thus, the reliability of the SOI substrates 17 and 18 can be simultaneously improved.

A first ion implantation step for forming the first ion implantation layer 13 is performed from one surface side of the single crystal silicon wafer 11, and a second ion implantation step for forming the second ion implantation layer 14 is performed. The process is performed on the single crystal silicon wafer 1
1 is performed from the other surface side, it is possible to strictly set the depth position of each of the ion-implanted layers 13 and 14, so that each of the SOI substrates 17 and 18 to be finally obtained is The thickness of the crystalline silicon thin films 11a and 11b can be easily controlled.

In this embodiment, since the ion implantation conditions in the first and second ion implantation steps are completely the same, the characteristics of the two SOI substrates 17 and 18 can be matched, and the same standard can be used. SOI substrate can be easily manufactured. If the ion implantation conditions in the first and second ion implantation steps are made different, two SOI substrates having different thickness dimensions of the single-crystal silicon thin film portion can be obtained at the same time.

In the present embodiment, the single-crystal silicon wafer 1 is subjected to a hydrophilic treatment performed before the bonding step.
1 and the surfaces of the base substrates 15 and 16 (that is, the surfaces of the insulating films 15a and 16a) are formed with natural oxide films (not shown), respectively. For this reason,
In the SOI substrates 17 and 18 manufactured through the bonding step and the subsequent peeling step and the heat treatment step, the SOI substrates 17 and 18 are between the single-crystal silicon thin film 11a and the insulating film 15a and between the single-crystal silicon thin film 11b and Between the single-crystal silicon thin film 11a and the insulating film 15a and the single-crystal silicon The bonding strength between the thin film 11b and the insulating film 16a is increased, and the reliability of the SOI substrates 17 and 18 is improved.

In this embodiment, when manufacturing the SOI substrates 17 and 18, the single-crystal silicon wafer 11 is used.
In order to ensure the quality of the single-crystal silicon thin films 11a and 11b, it is desirable to use a product wafer in which the impurity concentration is controlled to a constant value.
And 16 only need to fulfill the function of holding the single-crystal silicon thin film 11a or 11b via the insulating film 15a or 16a, and therefore a dummy wafer whose impurity concentration is not particularly controlled can be used.

As a result, inexpensive base substrates 15 and 16 can be used. Further, the single-crystal silicon substrate 11 'from which the single-crystal silicon thin films 11a and 11b have been separated through the separation step is subjected to the regeneration step. Is performed, the SOI substrates 17 and 18 can be reused when they are manufactured, and the resources can be effectively used. In this respect, the manufacturing cost can be reduced. .

(Second Embodiment) FIGS. 3 and 4 show a second embodiment of the present invention. Hereinafter, only portions different from the first embodiment will be described. FIGS. 3 and 4 are schematic cross-sectional views showing the steps of manufacturing the SOI substrate, similarly to FIGS. 1 and 2.

That is, in this embodiment, the preparation step shown in FIG. 3A, the protection film forming step shown in FIG. 3B, and the first ion implantation step shown in FIG. This is performed in the same manner as in the preparation step (see FIG. 1A), the protection film forming step (see FIG. 1B), and the first ion implantation step (see FIG. 1C) in the example.

In the second ion implantation step shown in FIG. 3D, hydrogen ions or hydrogen ions are implanted into the single-crystal silicon wafer 11 from the same side as the first ion implantation step, as indicated by arrows in the figure. By injecting rare gas ions,
A second ion implanted layer 14 'is formed in a distribution state parallel to the lower surface of the single crystal silicon wafer 11 in the figure.

The dose in the second ion implantation step is the same as the dose in the first ion implantation step, but the ion implantation energy is reduced to a predetermined depth in the second ion implantation layer 14 '. To raise it to the level needed to do so.

Thereafter, a protective film removing step shown in FIG. 3E, an insulating film forming step shown in FIG. 3F, a bonding step shown in FIG. 3G, and a peeling step shown in FIG. Process, FIG.
The flattening step shown in (i), the regenerating step shown in FIG. 4 (j) are replaced by a protective film removing step (see FIG. 1 (e)) and an insulating film forming step (see FIG. 1 (f)) in the first embodiment. , Bonding step (see FIG. 1 (g)), peeling step (see FIG. 2 (h)), flattening step (see FIG. 2 (i)), and regeneration step (FIG. 2).
By performing the same operation as in (j)), two SOI substrates 17 and 18 and a single-crystal silicon wafer 11 'to be reused can be obtained.

According to the above-described embodiment, the first ion implantation step for forming the first ion implantation layer 13 and the second ion implantation step for forming the second ion implantation layer 14 'are performed. Since the ion implantation may be performed from the same side of the single crystal silicon wafer 11, the single crystal silicon wafer 11 does not need to be turned over at the time of ion implantation, and the manufacturing process can be simplified accordingly.

In the second embodiment, the ion implantation depth in the first ion implantation step and the ion implantation depth in the second ion implantation step are made different from each other. By changing the constituent elements or the number of molecules of ions to be implanted in the first ion implantation step and the second ion implantation step, the ion implantation depth can be made different. In other words, the ion implantation depth is increased as the mass of the implanted ions becomes smaller if the implantation energy is the same. Therefore, in the first ion implantation step, the ion implantation depth is increased by using argon ions or chlorine ions. Can be set to be shallower, and in the second ion implantation step, the ion implantation depth can be set to be deeper by utilizing hydrogen ions, helium ions, or the like. Even when only hydrogen ions are used, H
^{By using +} and H2 ⁺ respectively, the implantation depth can be made different.

In addition, the present invention is not limited to the above-described embodiment, and the following modifications or extensions are possible. As the semiconductor substrate material, ion implantation can also be performed using a single crystal film formed by epitaxial growth on a single crystal silicon substrate or a single crystal film epitaxially grown on a porous film.

The single crystal silicon wafer 11 is used as the semiconductor substrate material. However, if the semiconductor is mainly composed of a Group 4 element, for example, Ge (germanium),
A substrate material such as SiC (silicon carbide) or SiGe (silicon germanium) can be used, or a polycrystalline silicon wafer can be used. Furthermore, although the base substrates 15 and 16 are formed of a single crystal silicon wafer provided with the insulating films 15a and 16a, the present invention is not limited to this, and other semiconductor wafers or insulating ceramic substrates or glass substrates may be used. it can.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a manufacturing process according to a first embodiment of the present invention;

FIG. 2 is a longitudinal sectional view schematically showing the manufacturing process, part 2

FIG. 3 is a longitudinal sectional view schematically showing a manufacturing process according to a second embodiment of the present invention;

FIG. 4 is a longitudinal sectional view schematically showing the manufacturing process, part 2

FIG. 5 is a longitudinal sectional view schematically showing an example of a conventional manufacturing process.

[Explanation of symbols]

11, 11 'are single crystal silicon wafers (semiconductor substrate materials), 11a, 11b are single crystal silicon thin films (semiconductor layers), 13 is a first ion implantation layer, 14, 14' are second ion implantation layers, 15, 16 Is a base substrate, 15a, 16a
Denotes an insulating film, and 17 and 18 denote SOI substrates (semiconductor substrates).

Claims (7)

[Claims] 1. A semiconductor substrate (17, 11) comprising a semiconductor substrate (11a, 11b) for element formation provided on a base substrate (15, 16) in a state of being electrically insulated from the base substrate (15, 16). 18) In the manufacturing method of (18), a first ion implantation step of forming a first ion implantation layer (13) by ion implantation at a predetermined depth position on one surface of the semiconductor substrate material (11); 11) a second ion implantation step of forming a second ion implantation layer (14, 14 ') by ion implantation at a predetermined depth position on the other surface of the other surface, and preparing two base substrates (15, 16) A bonding step of bonding the semiconductor substrate material (11) to both front and back surfaces, respectively, the semiconductor substrate material (11) and two base substrates (1);
By subjecting the integrated body of (5, 16) to a heat treatment, the semiconductor substrate material (11) is subjected to the first ion implantation layer (1).
4) and the second ion-implanted layer (14, 14 '), the semiconductor layer (11a,
A method for manufacturing a semiconductor substrate, comprising: performing a peeling step of forming 1b). 2. Following the peeling step, by performing a heat treatment at a temperature higher than the heat treatment temperature in the peeling step,
The base substrate (15, 16) and the semiconductor layer (11a,
2. The method according to claim 1, wherein a heat treatment step is performed to increase the bonding strength of the bonding surface between 11b). 3. In the first ion implantation step, ions are implanted from one surface side of the semiconductor substrate material (11), and in the second ion implantation step, the other of the semiconductor substrate material (11) is implanted. 3. The method for manufacturing a semiconductor substrate according to claim 1, wherein the ion implantation is performed from a surface side of the semiconductor substrate. 4. The semiconductor device according to claim 1, wherein in the first ion implantation step and the second ion implantation step, ion implantation is performed from the same surface side of the semiconductor substrate material to different depth positions. 3. The method for manufacturing a semiconductor substrate according to 1 or 2. 5. The method for manufacturing a semiconductor substrate according to claim 4, wherein the ion implantation energies in the first ion implantation step and the second ion implantation step are different from each other, so that the ion implantation depth is different. A method for manufacturing a semiconductor substrate, comprising: 6. The method of manufacturing a semiconductor substrate according to claim 4, wherein the ion implantation depth is changed by changing the number of constituent elements or the number of molecules of the ions implanted in the first ion implantation step and the second ion implantation step. A method of manufacturing a semiconductor substrate, wherein 7. The base substrate according to claim 1, wherein the base substrate is formed by forming an insulating film on a semiconductor substrate material. A method for manufacturing a semiconductor substrate according to any one of the above.