JPH056883A - Manufacture of semiconductor substrate - Google Patents

Abstract

PURPOSE:To provide a method for forming an SOI (Silicon on Insulator) substrate having excellent crystallinity. CONSTITUTION:An oxide film 2 is formed on a first silicon substrate 1, an epitaxial silicon grown film 4 is formed on a second silicon substrate 3, and both are bonded at the film 2 side and the film 4 side. The bonded laminated substrates are deleted at the substrate 3 until the film 4 is exposed, and an SOI structure of the film 4, the film 2, and the substrate 1, is obtained.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an SOI (Semiconducto)
The present invention relates to a method for manufacturing a semiconductor substrate having an r-On-Insulator) structure.

[0002]

2. Description of the Related Art An SOI substrate is one in which an insulating layer such as SiO ₂ is formed on a semiconductor silicon substrate to form an insulating substrate, and a semiconductor silicon layer is further formed on the insulating substrate.

However, the semiconductor silicon layer formed on the insulating layer, which is formed by laminating so-called bulk silicon, has poor crystallinity and has problems such as leak characteristics and withstand voltage characteristics.

On the other hand, a single-crystal semiconductor silicon layer formed by epitaxial growth has been used in a semiconductor device because it has few crystal defects and the control of impurities is easy (for example, JP-A-60-144949). Further, a method has been proposed in which the surfaces of two semiconductor substrates are mutually oxidized and the oxidized surfaces are bonded to each other (for example, JP-A-63-65648).

[0005]

However, when a silicon epitaxial layer is grown directly on an insulating substrate in order to form, for example, SOI, the silicon layer becomes amorphous or polycrystalline, so that it is made into a single crystal. To
Recrystallization process was required. Further, in the method of oxidizing two semiconductor substrates to each other and bonding the oxidized surfaces to each other, the oxide film surface has to be formed on the main surfaces of both substrates, which causes a problem that the number of manufacturing steps increases.

[0006] Therefore, an object of the present invention is to provide a method for manufacturing a semiconductor substrate in which a single crystal silicon epitaxial layer can be directly formed on an insulating substrate.

[0007]

In order to achieve the above object, the present invention provides a first step of forming an oxide film on the first surface of a first semiconductor substrate having a first surface, and a second step. A second step of forming a single crystal semiconductor layer on the second surface of the second semiconductor substrate having a surface and a third surface which is the back surface of the second surface, and the second step through the second step. A second semiconductor substrate having a single-crystal semiconductor layer formed on its two faces and the first surface of the first semiconductor substrate having an oxide film formed through the first step; And a fourth step of polishing the second semiconductor substrate bonded by the third step from the third surface side thereof until the single crystal semiconductor layer is exposed.

[0008]

According to the present invention, the semiconductor laminated substrate is formed by bonding the first semiconductor substrate having the oxide film and the second semiconductor layer having the single crystal semiconductor layer to each other with the above-described structure. Therefore, a single-crystal semiconductor layer with good crystallinity can be formed directly on the insulating substrate, and recrystallization treatment is unnecessary.

If an oxide film having a predetermined pattern is previously formed on the main surface of the second semiconductor substrate, the oxide film can be used as an oxide film for element isolation and also as a stopper for polishing. Can be used.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1A to 1D are cross-sectional views showing a method of manufacturing an SOI structure semiconductor substrate according to an embodiment of the present invention in the order of manufacturing steps.

First, as shown in FIG. 1A, SiO ₂ is formed on the surface of the first semiconductor silicon substrate 1 by the CVD method.
The film 2 is formed to have a thickness of 0.5 to 2 μm. At this time, for example, P
Phosphorus or boron 4 to 8 w using ₂ O ₅ or B ₂ O ₃
When t% is mixed, cracks are less likely to occur, which is preferable. A predetermined film may be formed by a thermal oxidation method other than the CVD method. In this case, SiO ₂ having a thickness of 1 μm or more is used.
Since the film formation requires a long time heat treatment, the CVD method is preferable.

On the other hand, as shown in FIG. 1B, a silicon epitaxial film 4 is formed on the second semiconductor silicon substrate 3.
Are grown to a thickness of 0.5 to 2 μm. The growth method is, for example, silane (SiH ₄ ) at a high temperature of 1150 to 1200 ° C.
Hydrogen reduction method.

Then, as shown in FIG. 1C, the first semiconductor silicon substrate 1 and the second semiconductor silicon substrate 3 are opposed to each other, and their principal surfaces are bonded together.
Heat treatment is performed in a steam atmosphere at a high temperature of 00 to 1200 ° C. to bond them to each other.

After that, the second semiconductor silicon substrate 3 is mechanically polished from its back surface side. Then, in a state where the second semiconductor silicon substrate 3 remains about 1 to 2 μm,
After stopping mechanical polishing, HF: HNO ₃ : CH ₃
Dissolve polish with a solution of COOH = 1: 3: 8. As a result, the silicon epitaxial film 4 is exposed as shown in FIG.

By configuring as described above, Si
It is possible to obtain an SOI substrate in which the single crystal silicon epitaxial film 4 is directly formed on the O ₂ film 2.

FIG. 2 shows a second embodiment of the present invention. In this embodiment, as shown in FIG. 2 (a), SiO _{2 having a} width of about 2 mm is previously formed on the peripheral portion of the second semiconductor silicon substrate 3.
The film 5 is formed to have a thickness of 1 to 2 μm. This SiO ₂ film 5
The film thickness of is equal to the film thickness of the silicon epitaxial film to be grown later.

Next, as shown in FIG.
The silicon epitaxial film 4 is grown only on the portion of the semiconductor silicon substrate 3 excluding the portion of the SiO ₂ film 5 by using the selective epitaxial growth technique.

Thereafter, as shown in FIG. 2C, as in the case of the above-described first embodiment, the second semiconductor silicon substrate 3 and the first semiconductor silicon substrate 1 having the SiO ₂ film 2 formed thereon are formed. Are bonded to each other and bonded by heat treatment.

Then, as shown in FIG. 2D, the second semiconductor silicon substrate 3 is polished from the rear surface side to expose the silicon epitaxial film 4. At this time, SiO ₂
Since the polishing rate of SiO ₂ is smaller than that of silicon, SiO ₂
The film 5 can be used as a stopper for polishing, so that the film thickness of the silicon epitaxial film 4 can be precisely controlled.

FIG. 3 shows a third embodiment of the present invention. In this embodiment, as shown in FIG. 3A, SiO for a polishing stopper is formed on the peripheral portion of the second semiconductor silicon substrate 3.
When forming the ₂ film 5, the SiO ₂ film 6 for element isolation is also patterned in advance at the same time.

After that, when the steps were carried out in the same manner as in the second embodiment, finally, as shown in FIG. 3D, the SiO ₂ portion 6 for element isolation was formed in the silicon epitaxial film 4. An SOI substrate can be obtained.

As in the present embodiment, Si for element isolation is used.
When the O ₂ film 6 is formed, the SiO ₂ film 6 can also be used as a polishing stopper, so that it is not necessary to form the SiO ₂ film 5 for the polishing stopper.
However, it is more advantageous in terms of work to have the polishing stopper in the peripheral portion of the second semiconductor silicon substrate 3 than in the central portion thereof. Therefore, it is more preferable to provide the SiO ₂ film 5.

[0023]

As described above, according to the present invention, since a semiconductor epitaxial layer having good crystallinity can be formed directly on an insulating substrate, a semiconductor laminated substrate having excellent characteristics can be obtained by a simple and reliable method. It can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view in order of the steps of a method for manufacturing a semiconductor substrate, which shows a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view in order of the steps of a method for manufacturing a semiconductor substrate showing a second embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view in order of the steps of a method for manufacturing a semiconductor substrate showing a third embodiment of the present invention.

[Explanation of symbols]

1 First semiconductor substrate 2 oxide film 3 Second semiconductor substrate 4 Single crystal semiconductor layer 5 Oxide film 6 oxide film

Claims (10)

[Claims] 1. A first step of forming an oxide film on the first surface of a first semiconductor substrate having a first surface, a second surface, and a third surface which is a back surface of the second surface. A second step of forming a single crystal semiconductor layer on the second surface of the second semiconductor substrate, and the second step of forming a single crystal semiconductor layer on the second surface through the second step. A third step of bonding the semiconductor substrate and the first surface of the first semiconductor substrate having the oxide film formed through the first step, and the second step of bonding by the third step. And a fourth step of polishing the semiconductor substrate from the third surface side thereof until the single crystal semiconductor layer is exposed. 2. The method of manufacturing a semiconductor substrate according to claim 1, wherein in the second step, a single crystal semiconductor layer is formed by an epitaxial growth method. 3. The method of manufacturing a semiconductor substrate according to claim 1, wherein the second semiconductor substrate and the single crystal semiconductor layer formed on the second surface of the second semiconductor substrate are made of a silicon material. 4. The manufacturing of a semiconductor substrate according to claim 1, further comprising a fifth step of forming an oxide film having a predetermined pattern on the second surface of the second semiconductor substrate before the second step. Method. 5. In a second step, after the fifth step, a single-crystal semiconductor layer is formed on the surface of the second semiconductor substrate on which the oxide film of the second surface is not formed. The method of manufacturing a semiconductor substrate according to claim 4, wherein 6. The method of manufacturing a semiconductor substrate according to claim 5, wherein in the second step, a single crystal semiconductor layer is formed by an epitaxial growth method. 7. The method of manufacturing a semiconductor substrate according to claim 1, wherein the third step includes heat treatment. 8. The method of manufacturing a semiconductor substrate according to claim 7, wherein the heat treatment is performed in a steam atmosphere. 9. The method of manufacturing a semiconductor substrate according to claim 7, wherein the heat treatment is performed in a temperature range of 1000 to 1200 ° C. 10. The fourth step comprises a mechanical polishing step,
The method of manufacturing a semiconductor substrate according to claim 1, further comprising a solution polishing step that follows.