JPH1012721A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide manufacture of a semiconductor device which enables formation of an SOI substrate having an insulating film with an arbitrary thickness and a thin activated silicon layer, isolation between elements, and planarization of the surface. SOLUTION: LOCOS oxidation is carried out on a single crystal silicon substrate 1, thereby forming a silicon oxide film 5 for element isolation. A polysilicon layer 6 is deposited on the side of the single crystal silicon substrate 1 where LOCOS oxidation has been carried out. Subsequently, the polysilicon layer 6 is transformed into a silicon oxide film 7 by thermal oxidation. Then, a single crystal silicon substrate 8 having a silicon oxide film 9 on one main surface thereof is separately prepared, and is bonded with the single crystal silicon substrate 1 in such a manner that the silicon oxide films 7, 9 face each other. The single crystal silicon substrate 1 is ground and abraded until at least a part of the silicon oxide film 5 is exposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for separating elements on an SOI substrate.

[0002]

2. Description of the Related Art Conventionally, an SOI (Silicon on Insulator) substrate has been used as a material for separating elements.

FIG. 2 is a schematic sectional view showing a method for manufacturing an SOI substrate according to a conventional example. The method for manufacturing the SOI substrate shown in FIG. 2 is based on SIMOX (Silicon Implanted Oxidatio).
This is called an n) method, in which an SOI substrate including a support silicon substrate 10, a silicon oxide film 11, and an active silicon layer 12 is formed by ion implantation of oxygen ions into a single crystal silicon substrate and heat treatment.

Further, as a method of manufacturing an SOI substrate, there is a method called a bonded SOI method, and FIG. 3 is a schematic cross-sectional view showing a manufacturing process of an SOI substrate according to a conventional example.
A silicon oxide film 2a formed on a single crystal silicon substrate 1a and a silicon oxide film 2b formed on a single crystal silicon substrate 1b are prepared (FIG. 3A). (FIG. 3B),
The single crystal silicon substrate 1b is thinned (see FIG. 3).
(C)) to manufacture an SOI substrate.

[0005]

SUMMARY OF THE INVENTION However, SIMOX
When an SOI substrate is manufactured by using the method, there is an advantage that the thickness accuracy of the active silicon layer 12 can be controlled with extremely high accuracy. However, the thickness of the silicon oxide film 11 depends on the amount of implanted oxygen ions. The silicon oxide film 11 has a thickness of 0.5 μm or more from the viewpoint of the injection amount limit due to the limit of the injection current and the suppression of lattice defects in the active silicon layer 12.
It is considered difficult to form silicon oxide 11
There is a problem that the thickness is limited to 0.5 μm or less.

Further, an SOI method using a bonding SOI method is used.
When the substrate is manufactured, the silicon oxide films 2a and 2b are bonded to each other, so that there is an advantage that the oxide film thickness can be set arbitrarily. In addition, since the thickness control is ± 5 μm, there is a problem that it is impossible to accurately reduce the thickness of the active silicon layer to 1 μm or less.

Here, if the chemical etching is performed locally by feeding back the measurement result of the film thickness, the thickness of the active silicon layer is reduced in principle because the film thickness control is ± 0.01 μm or less. Although it is possible, when the thickness of the silicon oxide film 11 is large, the warpage increases in proportion to the thickness, and a measurement error of the film thickness cannot be neglected. If a silicon oxide film is formed on the substrate 1, there is a problem that the plasma becomes unstable and etching cannot be performed.

As shown in FIG. 4, when the active silicon layer 12 of the SOI substrate is separated between elements by LOCOS oxidation, the silicon oxide film 5 formed by performing LOCOS oxidation rises above the active silicon layer 12. When wiring in this raised part,
There is a risk that the deposited metal for wiring may become thinner at the raised portion and break.

The present invention has been made in view of the above points, and has as its object to provide an S film having an insulating film of an arbitrary thickness and having a thinned active silicon layer.
An object of the present invention is to provide a method of manufacturing a semiconductor device capable of forming an OI substrate, performing element isolation, and planarizing the surface.

[0010]

According to the first aspect of the present invention,
A first insulating film is formed by performing LOCOS oxidation on one main surface of the first single crystal silicon substrate, and a second insulating film is formed on the side of the single crystal silicon substrate on which LOCOS oxidation has been performed until the surface is flattened. Formed, a second single-crystal silicon substrate having a third insulating film on one main surface is attached so that the second insulating film and the third insulating film face each other, the first single-crystal silicon substrate, The polishing is performed until at least a part of the first insulating film is exposed.

According to a second aspect of the present invention, in the method of manufacturing a semiconductor device according to the first aspect, the second insulating film is
It is characterized by using a silicon oxide film formed by a CVD method.

According to a third aspect of the present invention, in the method of manufacturing a semiconductor device according to the first aspect, the second insulating film is
It is characterized in that a silicon oxide film changed by performing thermal oxidation after forming a polysilicon layer is used.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating a manufacturing process of isolation between elements of an SOI substrate according to an embodiment of the present invention. First, a single-crystal silicon substrate 1 was heated at 900 ° C. for 2 hours.
By performing pyrogenic oxidation for 0 minutes, a silicon oxide film 2 of about 0.7 μm is formed (FIG. 1A).

Subsequently, after depositing a silicon nitride film 3 to a thickness of about 0.2 μm by using a low pressure CVD method or the like, a photoresist (not shown) is applied on the silicon nitride film 3 and exposed and developed. Is used to pattern the photoresist into a predetermined shape. Using the photoresist patterned in a predetermined shape as a mask, plasma etching of the silicon nitride film 3 is performed to form an opening 4 at a desired position in the silicon nitride film 3 and the photoresist is removed by plasma ashing or the like ( FIG. 1 (b).

Next, pyrogenetic oxidation is performed at 1100 ° C. for 100 minutes using the silicon nitride film 3 in which the opening 4 is formed as a mask to obtain about 1 μm for element isolation.
m silicon oxide film 5 is formed (FIG. 1C), and the silicon nitride film 3 is removed by plasma etching (FIG. 1).
(D)). Here, about half of the silicon oxide film 5 contributes from the single crystal silicon substrate 1, so that a portion of about 0.5 μm of the single crystal silicon substrate 1 below the opening 6 is Is replaced by

Next, a polysilicon layer 6 is formed to a thickness of about 3 μm using an epitaxial growth apparatus (FIG. 1E). At this time, the rise due to the formation of the silicon oxide film 5 is flattened by depositing the polysilicon layer 6 by about 3 μm.

Next, by performing pyrogenic oxidation at 1100 ° C. for 300 minutes, the polysilicon layer 8 is changed to a silicon oxide film 9 (FIG. 1F). Here, the oxidation rate of the polysilicon layer 8 is about 2 times that of single crystal silicon.
It is twice.

In this embodiment, after the polysilicon layer 6 is formed using the epitaxial growth apparatus, the polysilicon layer 6 is changed to the silicon oxide film 7 by performing pyrogenic oxidation.
The invention is not limited to this. If the silicon oxide film 7 is directly formed by the CVD method or the like, the step of FIG. 1E can be omitted.

Next, a single-crystal silicon substrate 8 is separately prepared, and pyrogenous oxidation is performed at 1100 ° C. for 150 minutes to form a silicon oxide film 9 of about 1 μm (FIG. 1 (g)). f) and the two wafers formed in FIG. 1G are bonded so that the silicon oxide films 7 and 9 face each other (FIG. 1H).

Finally, the surface of the single crystal silicon substrate 1 is flattened by grinding and polishing until at least a portion of the silicon oxide film 5 is exposed.

Therefore, in this embodiment, since the silicon oxide film 7 and the silicon oxide film 9 are bonded together, an SOI substrate having a silicon oxide film having an arbitrary thickness can be formed. In the present embodiment, the thickness of the element formation region is about １ ／ of the thickness of the silicon oxide film 5 formed by performing the LOCOS oxidation. The element formation region can be thinned accurately. Also,
Since the silicon oxide film 7 and the silicon oxide film 9 are bonded so that the silicon oxide film 5 formed by LOCOS oxidation is turned upside down, the area of the element formation region becomes larger than before, and the The effective area can be made larger than before. Further, since the surface is flattened by grinding and polishing the single crystal silicon substrate 1 until at least a part of the silicon oxide film 5 is exposed, it is possible to prevent the wiring between the element formation regions from being thinned. Can be.

The thickness of each layer in this embodiment is:
It is not limited to the film thickness of the present embodiment.

[0023]

According to the present invention, the first insulating film is formed by performing LOCOS oxidation on one main surface of the first single crystal silicon substrate, and the LOCOS oxidation of the single crystal silicon substrate is performed. The second insulating film is formed until the surface is flattened on the surface side on which the second monocrystalline silicon substrate having the third insulating film on one main surface is opposed to the second insulating film and the third insulating film. As described above, the first single crystal silicon substrate is polished until at least a part of the first insulating film is exposed, so that the second insulating film and the third insulating film are bonded to each other to have an arbitrary thickness. And the thickness of the element formation region is about の of the thickness of the first insulating film formed by performing LOCOS oxidation.
Therefore, by controlling the LOCOS oxidation conditions, the element formation region can be thinned with high precision, and since the second insulating film and the third insulating film are bonded to face each other, The first insulating film is turned upside down, the area of the element formation region becomes larger than before, the effective area for pattern formation can be made larger than before, and further, the first single crystal silicon substrate is Since at least a portion of one insulating film is polished until it is exposed, the surface has good flatness, an insulating film having an arbitrary thickness, and thinned active silicon. Forming an SOI substrate having a layer, separating elements,
In addition, a method for manufacturing a semiconductor device capable of planarizing a surface can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a manufacturing process of isolation between elements of an SOI substrate according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view illustrating a method for manufacturing an SOI substrate according to a conventional example.

FIG. 3 is a schematic sectional view showing a manufacturing process of an SOI substrate according to a conventional example.

FIG. 4 is a schematic cross-sectional view showing a method for separating elements of an SOI substrate according to a conventional example.

[Explanation of symbols]

 1, 1a, 1b Single-crystal silicon substrate 2, 2a, 2b Silicon oxide film 3 Silicon nitride film 4 Opening 5 Silicon oxide film 6 Polysilicon layer 7 Silicon oxide film 8 Single crystal silicon substrate 9 Silicon oxide film 10 Supporting silicon substrate 11 silicon oxide film 12 active silicon layer

Continuing on the front page (72) Inventor Yuji Suzuki 1048, Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Works Co., Ltd. Person Hitoshi Takano 1048 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Works, Ltd.

Claims (3)

[Claims] 1. A method according to claim 1, wherein one main surface of the first single crystal silicon substrate is L
Forming a first insulating film by performing OCOS oxidation, forming a second insulating film on the side of the single crystal silicon substrate on which the LOCOS oxidation has been performed until the surface is planarized, and forming a third insulating film on one main surface Are bonded so that the second insulating film and the third insulating film face each other, and the first single crystal silicon substrate is exposed at least a part of the first insulating film. A method of manufacturing a semiconductor device, wherein the semiconductor device is polished until it is finished. 2. The method according to claim 1, wherein a silicon oxide film formed by a CVD method is used as the second insulating film. 3. The method according to claim 1, wherein a silicon oxide film changed by performing thermal oxidation after forming a polysilicon layer is used as the second insulating film. .