JPH098124A - Insulation separation substrate and its manufacture - Google Patents

Abstract

PURPOSE: To easily control the amount of warpage of an insulation separation substrate to a desired value before forming an element. CONSTITUTION: A first silicon substrate 35 and a second silicon substrate 36 is heat-treated within oxidation environment to form oxide films 37 and 38 and 39 and 40 with a specific thickness each. Then, the first silicon substrate 35 and the second silicon substrate 36 are adhered and heat treatment is made in nitrogen atmosphere to manufacture a laminated substrate. Then, a surface at the side of the oxide film 37 of the first silicon substrate 35 is ground and the ground surface is polished to obtain SOI layer 41 with a desired thickness. Then, an insulation separation substrate 43 with a desired amount of warpage can be obtained from the film thickness difference between the film thickness of a buried oxide film 42 and that of an oxide film on the reverse surface being manufactured by the oxide films 38 and 39.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating separation substrate manufactured by a wafer bonding method and a method of manufacturing the same, and more specifically, an insulating separation substrate manufactured by a wafer bonding method capable of easily controlling the warp of the substrate. The present invention relates to a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing an insulating separation substrate, a manufacturing method based on the steps shown in FIG. 7 is known. That is, two silicon substrates, the first silicon substrate 1 and the second silicon substrate 2, are thermally oxidized in an oxidizing atmosphere to oxidize the oxide films 3 and 4 on the first silicon substrate 1 and the second silicon substrate 2. The films 5 and 6 are formed (FIG. 7A). After that, the first silicon substrate 1 and the second silicon substrate 2 are bonded together (FIG. 7B), and polishing is performed from one substrate side, in this case, the first silicon substrate 1 side, to a predetermined thickness to obtain an SOI ( Silicon On Insulat
or) layer 7 (FIG. 7C). In FIG. 7, 8 is an oxide film and 9 is an insulating separation substrate.

However, this method has a problem that a difference in thermal contraction rate occurs between the silicon and the oxide film, so that the substrate warps. A method for reducing the warp of the substrate is disclosed in, for example, JP-A-1-181438 or JP-A-1-181438.
No. 302740, etc.

The technique disclosed in JP-A-1-181438 mentioned above is capable of reducing the warp (average of 0 at -5 to +5 μm) by utilizing the difference in the interface between the silicon and the oxide film.

Further, in the above-mentioned Japanese Patent Laid-Open No. 1-203740, a first semiconductor layer integrated by adhesion with a first insulating film sandwiched therebetween, and a second semiconductor layer thicker than the first semiconductor layer are provided.
In the dielectric isolation substrate including the semiconductor layer of 1), there is described a technique of reducing the warp by providing an insulating film on the back surface of the second semiconductor layer and a protective layer covering the insulating film.

[0006]

However, it is not always necessary to set the amount of warpage of the insulating separation substrate to 0 (state without warpage), and a value at which warpage does not pose a problem in the device forming process which is a post process. Must be kept.
That is, in the device forming step, only the front side surface or the back side surface of the substrate is covered with a film such as an oxide film, a polycrystalline silicon film, or a nitride film having a coefficient of thermal expansion different from that of silicon over the entire surface or a part thereof. The residual stress is generated due to the periodical formation, and the warp amount of the substrate sequentially changes in each process.

For example, as shown in FIG. 8, the thickness of the SOI layer 10 is 10 μm, and the buried silicon oxide film 11 is formed.
Having a thickness of 1 μm, the silicon oxide film 13 on the back surface of the substrate 12
The insulation separation substrate with a thickness of 0.6 μm has a diameter of 150 m.
m, the thickness is 620 μm, and the convex shape is 3 toward the SOI layer 10 side.
The warp was 4 μm (FIG. 8 (a)). Then, on this substrate, after forming the trench 14 for insulating and isolating the element and the oxide film 15 on the sidewall of the trench, the trench 14 is filled with polycrystalline silicon 16 (FIG. 8B), and the oxidation on the SOI layer 10 is performed. The film and polycrystalline silicon are removed and the groove is flattened (FIG. 8C).
When the change of the warp of the substrate was examined by, the warp was 160 μm in a concave shape on the SOI layer 10 side. This warp change is
Polycrystalline silicon for burying the trench is also formed on the back surface by being deposited by LPCVD, so that the polycrystalline silicon 16 ′ (film thickness 4.5 μm) on the back surface largely warps the substrate.

If the warp becomes large in this way, the substrate cannot be straightened even by vacuum suction. Then, there arises a problem in exposure (transfer) in the photo process, which causes a problem that fine processing cannot be performed.

Even if the warp can be corrected by vacuum suction, a large stress is applied to the substrate during the correction, which may cause crystal defects or break the substrate. Therefore, even if the substrate is warped to the maximum, the amount of warp of the substrate is set to a predetermined value after the bonding and polishing steps as shown in FIG. 8A so that the above problem does not occur. It is desirable that the warp amount of the substrate be further convex toward the SOI layer side after the polishing step in the above example.

The present invention has been made in view of the above problems, and provides an insulating separation substrate capable of easily controlling the amount of warpage of the insulating separation substrate before element formation to a desired value, and a manufacturing method thereof. The purpose is to

[0011]

That is, an insulating separation substrate according to the present invention has a first silicon substrate having a silicon oxide film formed on at least one surface and a first silicon substrate having the silicon oxide film formed thereon. It is bonded to a silicon substrate and has a second silicon substrate having a silicon oxide film formed on one surface and the other surface thereof, and is formed by grinding and polishing the first silicon substrate to a predetermined thickness. In the insulating separation substrate, the film thickness of the silicon oxide film embedded between the first and second silicon substrates and the second
The amount of warpage of the silicon substrate is controlled based on the film thickness difference from the silicon oxide film formed on the other surface of the silicon substrate.

Further, in the method for manufacturing an insulating separation substrate according to the present invention, a silicon oxide film having a film thickness is formed on at least one surface of the first silicon substrate so that the substrate after polishing has a desired warp amount. 1 step, a second step of forming a silicon oxide film on one and the other surface of the second silicon substrate bonded to the first silicon substrate by heat treatment in an oxidizing atmosphere, and the second step of forming the first silicon substrate. A third step of cleaning and drying the surface on which the silicon oxide film is formed and the surface of the second silicon substrate on which the silicon oxide film is formed, and adhering the adhered first and second silicon substrates to each other. The method comprises a fourth step of forming a bonded substrate by performing heat treatment in a gas atmosphere, and a fifth step of grinding and polishing the other surface of the bonded silicon substrate of the first silicon substrate. The first step is to control the film thickness of the silicon oxide film formed on the first silicon substrate, and controlling the amount of warp of the substrate.

Further, in the method for manufacturing an insulating separation substrate according to the present invention, a silicon oxide film is formed on at least one surface of the first silicon substrate and one and the other surfaces of the second silicon substrate to be bonded to the first silicon substrate. A first step of forming, a second step of adhering the surface of the first silicon substrate on which the silicon oxide film is formed and the surface of the second silicon substrate on which the silicon oxide film is formed, after cleaning and drying. A third step of forming a bonded substrate by heat-treating the adhered first and second silicon substrates in an oxidizing atmosphere, and grinding the other surface of the bonded silicon substrate of the first silicon substrate, A fourth step of polishing, the third step controlling the film thickness of the silicon oxide film formed on the other surface of the second silicon substrate as much as the back surface of the insulating separation substrate, And controlling the amount of warping of the plate.

[0014]

In the insulating separation substrate of the present invention, the first silicon substrate and the second silicon substrate are bonded together via the silicon oxide film, and then the first silicon substrate is polished to a predetermined thickness. In the insulating separation substrate, the amount of warpage of the substrate can be controlled by the difference in the film thickness of the silicon oxide film embedded in the insulating separation substrate and the film thickness of the silicon oxide film on the back surface of the substrate.

In the method for manufacturing an insulating separation substrate according to the present invention, the amount of warpage of the substrate is determined by the difference in the film thickness of the silicon oxide film embedded in the insulating separation substrate and the film thickness of the silicon oxide film on the back surface of the insulating separation substrate. To control. The warp amount of this substrate can be controlled by controlling the film thickness of the silicon oxide film formed on the first silicon substrate before bonding.

Further, in the method for manufacturing an insulating separation substrate of the present invention, the warpage of the substrate is caused by the difference in the film thickness of the silicon oxide film embedded in the insulating separation substrate and the film thickness of the silicon oxide film on the back surface of the insulating separation substrate. Control the amount. Then, a heat treatment process for bonding the first silicon substrate and the second silicon substrate is performed in an oxidizing atmosphere to control the film thickness of the silicon oxide film formed on the surface of the bonded substrate on the second silicon substrate side. The amount of warpage of the substrate can be controlled.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. The warp of the substrate is obtained by bonding the first substrate and the second substrate through an oxide film and then polishing the first substrate to a predetermined thickness.
It is caused by the correlation with the oxide film on the back surface of the substrate. Therefore, first, the results of investigating the relationship between the warp of the substrate and the buried oxide film and the oxide film on the back surface of the substrate will be described with reference to FIGS.

First, in order to investigate the above-mentioned relationship, an insulating separation substrate is formed on the first substrate 21 as shown in FIG.
2 μm of 15 μm oxide films 23 and 24 on the second substrate 22.
Oxide films 25 and 26 of FIG. 2 are formed by heat treatment in an oxidizing atmosphere, the first substrate 21 and the second substrate 22 are bonded together as shown in FIG. It was produced by grinding and polishing as shown in (c). The SOI layer 29 of the insulating separation substrate has a thickness of 10 μm, and the buried oxide film 30 has a thickness of 2.15 μm. The diameter of the substrate is 150 mm, and the thickness after polishing is 620 μm.

H ₂ SO ₄ : H ₂ O ₂ =
After cleaning with a 4: 1 mixed solution and pure water are sequentially performed, the amount of water adsorbed on the substrate surface is controlled by spin drying to bring the first and second substrates 21 and 22 into close contact with each other. As a result, the first and second substrates 21 and 22 are bonded to each other by hydrogen bonds of silanol groups formed on their surfaces and water molecules adsorbed on the surfaces.

After that, the first and second substrates 21 bonded together,
22 at 1100 ° C. in a nitrogen atmosphere which is an inert gas,
By performing the heat treatment for 1 hour, a dehydration condensation reaction is caused on the adhesive surface, and the two substrates 21 and 22 are directly bonded and integrated. As a result, the bonded substrate stack 27 is formed.

Next, the other surface 28 of the first substrate 21, that is, the surface which is not in contact with the second substrate 21 is ground and polished to obtain the SOI layer 29 and to reduce the thickness as described above. 10 μm. In this case, the thickness of the buried oxide film 30 is 2.15 μm, and the thickness of the back oxide film 26 is 2 μm.

Four substrates were prepared by the above method,
After measuring the warpage of these four substrates, the oxide film on the back surface was etched with a hydrofluoric acid solution to obtain 2.0 μm.
To 1.5 μm, 1.0 μm, 0.5 μm, and 0 μm
Correspondence with the warp was investigated by successively decreasing the film thickness with m.

As a result, the relationship between the warp of the substrate and the thickness of the oxide film on the back surface of the substrate is shown by a black circle in FIG. 3 (a). In this case, all the warp directions are convex toward the first substrate 21 side (SOI layer 29 side).

Here, it is understood that when the thickness of the buried oxide film is constant, the warp of the substrate and the thickness of the oxide film on the back surface of the substrate are in a substantially proportional relationship. As can be seen from FIG. 3A, the warp approaches 0 as the oxide film thickness on the back surface of the substrate approaches the buried oxide film thickness (2.15 μm in this case). This means that since the buried oxide film thickness is fixed at 2.15 μm, the film thickness difference between the oxide film on the back surface of the substrate and the buried oxide film (hereinafter, simply referred to as film thickness difference) and the warp of the substrate. Can be said to have a proportional relationship.

In order to confirm the proportional relationship between the film thickness difference and the warp, the film thicknesses of the oxide film and the buried oxide film on the back surface of the substrate were arbitrarily set to the numbers 1 to 7 shown in FIG. 3B. The warp of the substrate was examined. The mark x shown in FIG. 3A represents the relationship between the film thickness difference and the warp, and the substrates of the numbers 1 to 7 appear on the proportional straight line indicating the proportional relationship.
Although the thickness of the SOI layer is different, if the thickness is within this range, the influence on the amount of warp is small. The variation also depends on the warped state of the second substrate before bonding.

As described above, when the thickness and the diameter of the substrate are equal, the difference in film thickness and the amount of warpage are in a proportional relationship.
It can be seen that the amount of warp of the substrate can be controlled by adjusting this film thickness difference.

Further, as shown in FIGS. 4A to 4C, the first silicon substrate 31 and the second silicon substrate 32 have a film thickness t ₁ and a film thickness t, respectively, by heat treatment in an oxidizing atmosphere. _{When the two} oxide films are formed and then adhered to each other and the heat treatment for bonding is performed in an atmosphere of an inert gas such as nitrogen, the thickness of the buried oxide film 34 of the insulating separation substrate 33 is (t
₁ + t ₂ ), the film thickness of the oxide film 35 on the back surface is t ₂ , and the film thickness difference is the film thickness t of the oxide film formed on the first silicon substrate 31.
Is equal to ₁ .

Therefore, by controlling the film thickness t ₁ of the oxide film formed on the first silicon substrate, it becomes possible to control the warp amount of the insulating separation substrate. From the above results, in the case of an insulating separation substrate having a diameter of 150 mm and a thickness of 620 μm, the relational expression of warpage amount (μm) = 71 × t ₁ +4 (μm) (1) is established.

Next, a first embodiment of the present invention will be described with reference to FIG. Here, for example, with respect to an insulating separation substrate having a buried oxide film thickness of 2.0 μm, an SOI layer thickness of 10 μm, a substrate size of 150 mm and a substrate thickness of 620 μm, the warpage amount is convex to the SOI layer side. 20 μm
The case of controlling to be described.

The insulating separation substrate before bonding according to the first embodiment has a first silicon substrate 35 and a second silicon substrate 36, as shown in FIG. Oxide films 37 and 38 are formed on 35, and oxide films 39 and 40 are formed on the second silicon substrate 36. These oxide films are formed as follows.

The amount of warpage is 20 μm when it is convex on the SOI layer side.
In order to achieve this, the film thickness difference may be specified as described above. That is, the thickness of the oxide film formed on the first silicon substrate 35 is 0.23 from FIG. 3A (the above relational expression (1)).
It may be set to μm. Therefore, as shown in FIG. 1A, for example, dry O ₂
Heat treatment is performed in an oxidizing atmosphere such as wet O ₂ or H ₂ / O ₂ mixed combustion gas to form an oxide film 38 having a thickness of 0.23 μm. Further, the second silicon substrate 36 is similarly heat-treated in an oxidizing atmosphere to form oxide films 39 and 40 having a film thickness of 1.77 μm.

Thereafter, as shown in FIG. 1B, the first silicon substrate 35 and the second silicon substrate 36 are brought into close contact with each other, and heat treatment is performed in a nitrogen atmosphere at, for example, 1100 ° C. for 1 hour. . Next, as shown in FIG. 1C, the other surface of the first silicon substrate 35 (on the oxide film 37 side)
Is ground and the ground surface is ground to obtain an SOI layer 41 having a film thickness of 10 μm.

As a result, the thickness of the buried oxide film 42 is 2 μm.
m, the thickness of the oxide film 40 on the back surface is 1.77 μm, and the thickness difference is 0.
An insulating separation substrate 43 having a warp amount of 23 μm and a convex shape on the SOI layer side of 20 μm can be obtained.

Next, a second embodiment of the present invention will be described. FIG. 5 is similar to the above-described first embodiment, in the insulating isolation substrate having a buried oxide film thickness of 2.0 μm and an SOI layer thickness of 10 μm, the warpage amount is controlled to 20 μm in a state of being convex toward the SOI layer side. It shows the case.

As shown in FIG. 5A, the first silicon substrate 45 and the second silicon substrate 46 are heat-treated in an oxidizing atmosphere, so that the first and second silicon substrates 45 and 46 have a thickness of 1 μm. Oxide films 47, 48 and 49, 50 are formed.

Next, as shown in FIG. 5B, the first
The silicon substrate 45 and the second silicon substrate 46 are brought into close contact with each other. Then, heat treatment is performed to directly bond the first silicon substrate 45 and the second silicon substrate 46. This heat treatment is performed in an oxidizing atmosphere to increase the oxide film thickness of the oxide film 50 on the other surface of the second silicon substrate 46 as much as the back surface of the insulating separation substrate, thereby adjusting the film thickness difference. Control warpage of the board. In the second embodiment, thermal oxidation is performed under the condition that the film thickness 1 μm of the back oxide film 50 is 1.77 μm.

Thereafter, as shown in FIG. 5C, the other surface (on the side of the oxide film 47 ') of the first silicon substrate 45 is ground as in the first embodiment described above. Then, the ground surface is polished to obtain a 10 μm SOI layer 51.

Thus, the buried oxide film 52 has a film thickness of 2 μm, the back oxide film 50 ′ has a film thickness of 1.77 μm, and the film thickness difference is 0.23 μm, and the warp is 20 on the SOI layer 51 side.
It is possible to obtain the insulating separation substrate 53 of μm.

By the way, as in the above-mentioned embodiment, the thickness of the buried oxide film is as thick as 2 μm or more, and the warp amount is S
When it is desired to reduce the thickness to 20 μm or less in the state of being convex or concave on the OI layer side, the oxide film thickness on the back surface also needs to be thick (1.77 μm or more). Therefore, the manufacturing method of the first embodiment is used, or the oxide film thickness of the second silicon substrate of the second embodiment before bonding is made as thick as possible, that is, close to the buried oxide film thickness. It is desirable to make it.

With respect to the latter, by performing the heat treatment for bonding in a short time, it is possible to reduce the heat load on the first silicon substrate to be the active layer, and to suppress the occurrence of crystal defects.

Further, in the above-mentioned first and second embodiments, an example of the control for warping the SOI layer side to the convex state has been described. However, as is clear from FIG. 3, the oxide film on the back surface is filled with the buried oxide film. If the thickness is made thicker, the amount of warp can be similarly controlled in the concave state on the SOI layer side by the difference in the film thickness.

FIG. 6 shows, as a third embodiment, an insulating isolation substrate having a buried oxide film thickness of 2.0 μm and an SOI layer thickness of 10 μm, in which the amount of warpage is 20 on the SOI layer side.
It shows the case of controlling to μm.

The amount of warpage is 20 μ when concave on the SOI layer side.
In order to set m, that is, the amount of warpage to −20 μm, the film thickness difference must be −0.34 μm from the above relational expression (1).

Therefore, as shown in FIG. 6A, for example, the first silicon substrate 65 is provided with oxide films 67 and 68 having a film thickness of 0.2 μm, and the second silicon substrate 66 is provided with a film thickness of 1.8.
The μm oxide films 69 and 70 are formed by heat treatment in an oxidizing atmosphere.

Next, as shown in FIG. 6B, the first silicon substrate 65 and the second silicon substrate 66 are brought into close contact with each other. Next, in this state, a heat treatment for directly joining the first silicon substrate 65 and the second silicon substrate 66 is performed. By performing this heat treatment in an oxidizing atmosphere, the second
The oxide film thickness of the oxide film 70 on the other surface of the silicon substrate 66 (back surface of the insulating separation substrate) is increased to 1.8 μm to 2.34 μm.

After this, as shown in FIG. 6C, the other surface (on the side of the oxide film 67 ') of the first silicon substrate 65 is ground. Then, the ground surface is polished to obtain a 10 μm SOI layer 71.

As a result, the thickness of the buried oxide film 72 is 2 μm.
m, the film thickness of the oxide film 70 'on the back surface is 2.34 μm, and the film thickness difference −
Since the insulating separation substrate 73 has a warp of SO4
The concave shape is 20 μm on the I layer 71 side.

[0048]

As described above, according to the present invention, it is possible to provide an insulating separation substrate capable of easily controlling the amount of warpage of the insulating separation substrate before element formation to a desired value, and a manufacturing method thereof.

[Brief description of drawings]

FIG. 1 is a view for explaining the first embodiment of the present invention and is a diagram showing a manufacturing process of an insulating separation substrate.

FIG. 2 is a view for explaining the relationship between the warp of the insulating separation substrate and the buried oxide film and the oxide film on the back surface of the substrate, and a diagram showing the manufacturing process of the insulating separation substrate.

FIG. 3 illustrates the relationship between the warpage of the insulating separation substrate and the buried oxide film and the oxide film on the back surface of the substrate. FIG. 3A is a diagram showing the relationship between the film thickness difference of the insulating separation substrate and the amount of warpage. , (B)
FIG. 4 is a diagram showing a substrate with the thicknesses of an oxide film and a buried oxide film on the back surface of the substrate as parameters.

FIG. 4 is an explanatory diagram showing control of warpage of the insulating separation substrate according to the first embodiment.

FIG. 5 is a view for explaining the second embodiment of the present invention and is a diagram showing a manufacturing process of an insulating separation substrate.

FIG. 6 is a view for explaining the third embodiment of the present invention and is a diagram showing a manufacturing process of an insulating separation substrate.

FIG. 7 is a diagram showing an example of a manufacturing process of a conventional insulating separation substrate.

FIG. 8 is a diagram showing another example of a conventional manufacturing process of an insulating separation substrate.

[Explanation of symbols]

21 ... First substrate, 22 ... Second substrate, 23, 24, 25,
26, 37, 38, 39, 40 ... Oxide film, 27 ... Bonded substrate, 28 ... Other surface, 29, 41 ... SOI layer, 3
0, 42 ... Buried oxide film, 35 ... First silicon substrate, 3
6 ... 2nd silicon substrate, 43 ... Insulation separation substrate.

Claims (12)

[Claims] 1. A first silicon substrate having a silicon oxide film formed on at least one surface thereof, and the first silicon substrate bonded to the surface having the silicon oxide film formed thereon. A second silicon substrate having a silicon oxide film formed on the other surface, and an insulating separation substrate formed by grinding and polishing the first silicon substrate to a predetermined thickness. The amount of warpage of the substrate is controlled based on the difference in film thickness between the silicon oxide film embedded between the two silicon substrates and the silicon oxide film formed on the other surface of the second silicon substrate. An insulating separation substrate characterized by being. 2. The second silicon substrate is characterized in that a silicon oxide film is not formed on one surface to be bonded to the first silicon substrate, and a silicon oxide film is formed only on the other surface. The insulating separation substrate according to claim 1. 3. The silicon oxide film is not formed on the first silicon substrate, and the silicon oxide film is formed on one surface and the other surface of the second silicon substrate. The insulating isolation substrate described. 4. The insulating separation substrate according to claim 1, wherein the film thickness of the silicon oxide film formed on the first silicon substrate and the second silicon substrate is determined by the diameter and thickness of the insulating separation substrate. . 5. A first step of forming a silicon oxide film having a film thickness on a surface of at least one surface of a first silicon substrate so that the substrate after polishing has a desired warp amount, and the first silicon substrate is bonded to the first step. A second step of forming a silicon oxide film on one surface and the other surface of the second silicon substrate by performing a heat treatment in an oxidizing atmosphere; a surface of the first silicon substrate on which the silicon oxide film is formed; A third step of cleaning and drying the surface of the substrate on which the silicon oxide film is formed, and then adhering the same, and heat-treating the adhered first and second silicon substrates in an inert gas atmosphere to form a bonded substrate. And a fifth step of grinding and polishing the other surface of the first silicon substrate out of the bonded substrate, the first step comprising the oxidation formed on the first silicon substrate. By controlling the thickness of the silicon film, the manufacturing method of the isolation substrate and controlling warpage of the substrate. 6. The silicon oxide film formed on the first silicon substrate in the first step is formed by heat treatment in an oxidizing atmosphere. 5. The method for manufacturing an insulating separation substrate according to 5. 7. The method for manufacturing an insulation separation substrate according to claim 5, wherein the film thickness of the silicon oxide film formed on the first silicon substrate is determined by the diameter and thickness of the insulation separation substrate. 8. A first step of forming a silicon oxide film on at least one surface of a first silicon substrate and one and the other surfaces of a second silicon substrate to be bonded to this first silicon substrate, and the first step. 1. A second step of cleaning and drying one surface of the silicon substrate on which the silicon oxide film is formed and one surface of the second silicon substrate on which the silicon oxide film is formed; 2 A third step of forming a bonded substrate by subjecting the silicon substrate to a heat treatment in an oxidizing atmosphere, and a fourth step of grinding and polishing the other surface of the bonded silicon substrate of the first silicon substrate. The third step is characterized in that the thickness of the silicon oxide film formed on the other surface of the second silicon substrate as much as the back surface of the insulating separation substrate is controlled to control the amount of warpage of the substrate. Manufacturing method of isolation substrate. 9. The silicon oxide film formed on the first silicon substrate and the second silicon substrate in the first step is formed by heat treatment in an oxidizing atmosphere. The method for manufacturing an insulating separation substrate according to claim 8, wherein the insulating separation substrate is manufactured. 10. The method of manufacturing an insulating separation substrate according to claim 8, wherein in the first step, a silicon oxide film is formed only on the second silicon substrate. 11. The method according to claim 8, wherein in the first step, a silicon oxide film is formed only on one surface of the second silicon substrate. 12. The film thickness of the silicon oxide film formed on the other surface of the second silicon substrate in the third step is determined by the diameter and thickness of the insulating separation substrate. A method for manufacturing the insulating and separated substrate described.