JPH0344912A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To form symmetry with respect to material and structure, to prevent warpage due to a heat treatment and to improve an accuracy of miniaturization by adhesively bonding thin semiconductor films having equal thickness on both side surfaces of a semiconductor substrate through insulating layers. CONSTITUTION:Thermal oxide films 4 are formed on whole surfaces including both side surfaces of a silicon substrate 2, and silicon layers 6, 8 are formed on both side surfaces of the substrate 2 through the films 4. In this case, the face orientation of both the substrate 2 and the layers 6, 8 are brought into agreement. The thus formed substrate is kept symmetric with respect to materials and structures on the front and rear surfaces, and mismatches of thermal expansion coefficients of the substrate 2, the layers 6, 8 and the films 4 are cancelled to each other at the front and rear surfaces. Accordingly, even if it is heat treated, it can prevent warpage. Thus, a fine pattern processing can be facilitated to enhance its accuracy.

Description

[Detailed Description of the Invention] [vA Required] Relates to semiconductor devices and M36 methods thereof, particularly wafer-bonded SOI (5ilicon On In5ul)
The purpose of the present invention is to provide a semiconductor substrate and a manufacturing method thereof that can prevent the occurrence of warpage due to heat treatment during the process and improve the accuracy of rR fine processing. The semiconductor device is configured to have first and second insulating layers formed on both sides of a semiconductor substrate, respectively, and first and second semiconductor layers adhesively bonded on the first and second insulating layers, respectively. , a step of forming first and second insulating layers on both surfaces of the first semiconductor substrate, respectively, and adhesively bonding second and third semiconductor substrates on the first and second insulating layers, respectively. and a step of polishing both exposed surfaces of the second and third semiconductor substrates to form first and second semiconductor layers.

[Industrial Field of Application] The present invention relates to a semiconductor device and a method for manufacturing the same, and particularly relates to a wafer-bonded SoI (Silicon On In5) semiconductor device and a method for manufacturing the same.
ulator) substrate and its manufacturing method.

[Prior Art] In recent years, Sol substrates have been expected to serve as semiconductor substrates that have excellent soft error resistance and can achieve high speeds in the context of higher integration of memory devices and higher speeds of digital devices. However, at the same time, it is required to solve problems such as stably supplying SOf substrates and matching them to device processes. In particular, there is an urgent need to solve the problem of warpage of the Sol substrate that occurs during the process.

That is, in a conventional silicon wafer bonded SOI substrate, a silicon thin film is adhesively bonded to one side of a silicon substrate via a silicon oxide film.

At this time, the thermal expansion coefficient of the silicon substrate is 3.5 x 10-
6, whereas the thermal expansion coefficient of silicon oxide film is 0.
5X10-', and there is a difference in order, SOI
Residual stress always exists in the substrate.

Therefore, heat treatment during the process causes large warpage in the SOI substrate. This can be said to be the same principle as that of bimetals, where warping occurs when joining dissimilar metals with different coefficients of thermal expansion.

[Problems to be Solved by the Invention] In this way, the above-mentioned conventional silicon wafer bonded SOI
Since the substrate is greatly warped due to heat treatment during processing, it has been difficult to perform microfabrication such as forming a fine pattern on the SOI substrate.

Therefore, it is an object of the present invention to provide a semiconductor device and a method for manufacturing the same, which can prevent warpage caused by heat treatment during processing and improve the precision of microfabrication.

[Means for Solving the Problems] The above-mentioned problems include a semiconductor substrate, first and second insulating layers formed on both sides of the semiconductor substrate, and adhesion on the first and second insulating layers, respectively. This is achieved by a semiconductor device characterized by having first and second semiconductor layers that are bonded together.

The above problem also includes forming first and second insulating layers on both sides of a first semiconductor substrate, and forming second and third semiconductor substrates on the first and second insulating layers, respectively. A method for manufacturing a semiconductor device, comprising the steps of adhesively bonding the exposed surfaces of the second and third semiconductor substrates, and polishing both sides of each exposed surface of the second and third semiconductor substrates to form first and second semiconductor layers. achieved.

[Function] That is, in the present invention, semiconductor thin films are bonded to both surfaces of a semiconductor substrate via insulating layers, respectively. Due to the FJ construction, the overall structure is symmetrical both in terms of material and selection, and no warpage occurs during heat treatment.

[Example] The present invention will be specifically described below based on an illustrative example.

FIG. 1 is a sectional view showing a semiconductor device according to an embodiment of the present invention.

A thermal oxide film 4 with a thickness of 1 to 2 μm is formed on the entire surface including both the front and back surfaces of a silicon substrate 2 with a thickness of 500 μm.

On both sides of the silicon substrate 2 through this thermally oxidized WA4,
A silicon layer 6.8 is formed, each having a thickness of 3 to 10 JJ, m. At this time, the plane orientations of the silicon substrate 2 and the silicon layer 6.8 are made to match.

In this way, an SOI ellipse is formed by the thermal oxide film 4 and one of the silicon layers 6 and 8 on the thermal oxide film 4.

At this time, silicon layer 6 - sad oxidation M4 - silicon substrate 2
S composed of a structure of - thermal oxide film 4 - silicon layer 8
Since the OI substrate maintains symmetry both in terms of material and structure on its front and back sides, mismatching between the thermal expansion coefficients of the silicon substrate 2 and the silicon layer 6.8 and that of the thermally oxidized WA4 is avoided. Cancelled between front and back.

Therefore, even if an SOI substrate is used and heat treatment is performed in the process of forming a semiconductor element on one of the silicon layers 6 and 8, the SOI
No major warping occurs on the I-board.

As described above, according to this embodiment, by making the SOI substrate symmetrical in terms of material and structure, it is possible to prevent warping due to heat treatment during the process. Therefore, in a process using this flat SOI substrate, microfabrication such as forming a micropattern can be easily performed, and the precision thereof can be improved.

Next, a method for manufacturing the semiconductor device shown in FIG. 1 will be explained using FIG. 2.

Thermal oxidation [4] is grown to a thickness of 1 to 2 μm on the entire surface including both the front and back surfaces of a silicon substrate 2 having a thickness of 500 ALm (FIG. 2(a)).

Next, a silicon substrate 10.12 having a thickness of 500 μm and having the same surface orientation as the silicon substrate 2 and having a desired resistivity necessary for forming a semiconductor element in a later step is prepared.
Then, a hydrophilic treatment is performed to form a chemical oxide using an acid such as HNO3, and the silicon substrate 10.12 whose surface has become hydrophilic is bonded onto both sides of the silicon substrate 2 via thermal oxidation M4. Crimp. Further, an annealing treatment is performed at a temperature of 800° C. for 30 minutes in an oxidizing atmosphere to bond the silicon substrate 10.12 and the thermal oxidation @4 at the atomic level. In this way, the silicon substrates 10 and 12 are V-bonded to both sides of the silicon substrate 2 via the thermal oxide film 4 (FIG. 2(b)).

Next, mechanical polishing and chemical polishing using, for example, alumina powder and KOHl or alumina powder and ethylenediamine are performed to form the silicon substrate 10.12.
Polish the exposed surface at the same time.

Then, by this double-sided polishing, the silicon layer is polished to a desired thickness necessary for forming a semiconductor element in a later process. Then, silicon layers 6 and 8 are formed.

In this way, the thermal oxide film 4 and the silicon N on this thermal oxidation [4]
An SOI substrate is manufactured that constitutes an SOI structure with either silicon layer 6 or 8 (Fig. 2 ((:)).
.

The present invention is not limited to the above-mentioned embodiments, and various modifications are possible.

For example, in the above embodiment, the semiconductor substrate is a silicon substrate, the insulating layer is a thermal oxide film, and the semiconductor layer is a silicon layer, but other materials may be used.

[Effects of the Invention] As described above, according to the present invention, by creating a structure in which semiconductor thin films of approximately equal film thickness are adhesively bonded on both sides of a semiconductor substrate via insulating layers, the material quality as a whole can be improved. , the WJ structure can be made symmetrical, and warping due to heat treatment during the process can be prevented. This makes it possible to improve the precision of microfabrication.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a process diagram showing a method for manufacturing the semiconductor device shown in FIG. In the figure, 2.10.12...Silicon substrate 4...Thermal oxide film 6.8...Silicon layer 2: Silicon substrate 4: Thermal oxide film 6.8: Silicon layer According to an embodiment of the present invention Cross-sectional view showing a semiconductor device FIG. 1 FIG. 2: Silicon substrate 4: Thermal oxide film 10.12: Silicon substrate 6.8: Silicon layer FIG.

Claims (1)

[Claims] 1. A semiconductor substrate; first and second insulating layers respectively formed on both sides of the semiconductor substrate; and a first insulating layer adhesively bonded on the first and second insulating layers, respectively. and a second semiconductor layer. 2. Forming first and second insulating layers on both surfaces of the first semiconductor substrate, respectively; and forming second and third insulating layers on the first and second insulating layers, respectively.
bonding the semiconductor substrates together, and polishing both exposed surfaces of the second and third semiconductor substrates to form the first and second semiconductor substrates.
1. A method for manufacturing a semiconductor device, comprising: forming a semiconductor layer.