JPH05152180A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To reduce the manufacturing cost of an SOI cladding wafer, which is produced by adhering two silicon wafers with each other, while its quality with respect to the formation of a semiconductor element is maintained. CONSTITUTION:In an SOI cladding wafer made of two silicon wafers which are adhered with each other having a dielectric film sandwiched therebetween, a polysilicon wafer 1 is used as one of these wafers, and a silicon single crystal wafer 2 is used as the remaining wafer. A semiconductor element is formed on the silicon single crystal wafer 2 side of the cladding wafer. A silicon oxide film is used as a dielectric film, and at least one surface of at least one wafer of the polysilicon wafer 1 and the silicon single crystal wafer 2 is oxidized. This oxidized surface is brought into contact with the other wafer, and these two wafers are adhered with each other by annealing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to semiconductor technology and further to
Two silicon wafers are bonded together via an insulating film,
The present invention relates to a technique effectively used for a so-called "SOI" bonded wafer in which a semiconductor element such as a transistor is formed on one of the silicon wafers.

[0002]

2. Description of the Related Art As a method for manufacturing an SOI bonded wafer, an insulating film of a silicon oxide film is formed on at least one surface of two silicon single crystal wafers, and the two silicon single crystal wafers are interposed with the insulating film interposed therebetween. A method of pasting is known in Journal of Applied Physics, Volume 60 (1986), page 2987. Then, one of the two silicon single crystals bonded together in this manner is polished to a predetermined thickness (several μm), and the silicon single crystal wafer on the polished side is
A semiconductor element (LSI circuit) is formed. The SOI wafer having such a structure is effective against a soft error due to α rays because an insulating film is formed between two silicon wafers.

[0003]

However, the present inventors have clarified that the above-mentioned technique has the following problems. That is, in the above SOI bonded wafer, a semiconductor element (LSI circuit) is actually used.
However, in the conventional SOI bonded wafer, a high-priced silicon single crystal wafer is used for the surface on which the semiconductor element is not formed, so that the manufacturing cost of the wafer is reduced. No consideration was given to sex. The present invention has been made in view of the above circumstances, and it is possible to reduce the manufacturing cost of an SOI bonded wafer formed by bonding two silicon wafers while maintaining the same quality as before in semiconductor device formation. An object of the present invention is to provide a semiconductor device that can be manufactured and a manufacturing method thereof.

[0004]

The typical ones of the inventions disclosed in the present application will be outlined below. That is, in forming two SOI wafers by bonding two silicon wafers via an insulating film, one silicon wafer was a silicon polycrystal wafer and the other silicon wafer was a silicon single crystal wafer.

[0005]

According to the above means, the silicon wafer on the side where the semiconductor element is formed is formed on the surface and / or inside of the silicon wafer.
As before, the silicon single crystal wafer can be used, and the side on which the semiconductor element is not formed (on the side of the support substrate) can be the silicon wafer with low manufacturing cost.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a partial sectional view of an SOI laminated wafer according to the present invention. In the figure, reference numeral 1 denotes a wafer which constitutes a supporting substrate, and in this embodiment, a silicon polycrystalline wafer is used. Further, in the figure, 2 is a silicon single crystal wafer on which semiconductor elements are formed on the surface and / or inside,
Reference numeral 3 is an insulating film made of silicon oxide.

First, a method for manufacturing a silicon polycrystalline wafer used as a support substrate for the SOI bonded wafer will be described in comparison with a method for manufacturing a silicon single crystal wafer.

In forming a silicon polycrystalline wafer, high-purity trichlorosilane (S) refined in a reaction furnace is used.
iHCl ₃ ), tetrachloride (SiCl ₄ ), or dichlorosilane (SiH ₂ Cl ₂ ) is hydrogen-reduced, or monosilane (SiH ₄ ) is thermally decomposed.
Silicon is deposited around a 10-mm polycrystalline silicon core wire to produce a polycrystalline silicon ingot of a predetermined thickness. Next, the polycrystalline silicon
The ingot is processed (cylindrical grinding-slice-lap-polishing) to produce a silicon polycrystalline wafer.

On the other hand, in forming a silicon single crystal wafer, (i) the polycrystalline silicon ingot produced by the above-mentioned methods (1) is once crushed into a lump and thrown into a quartz crucible provided in a crystal growth furnace, This is melted by heating and then grown by the pulling method (Czochralski method) to obtain a single crystal silicon ingot. (ii) The single crystal silicon ingot is processed by cylindrical grinding-slice-lap-polish in the same manner as above to manufacture a silicon single crystal wafer. When the above manufacturing methods are compared with each other, the manufacturing cost of the silicon polycrystalline wafer is lower than that of the single crystal wafer because the silicon single crystal growth step is not required. Therefore, in this embodiment,
As described above, an inexpensive silicon polycrystalline wafer is used as a support substrate for an SOI bonded wafer, and the entire SOI wafer is manufactured as compared with a conventional SOI bonded wafer using two silicon single crystal wafers. The cost is being reduced.

The process of bonding the silicon polycrystal wafer 1 and the silicon single crystal wafer 2 will be described below. First, on the surfaces of the silicon polycrystal wafer 1 and the silicon single crystal wafer 2, a silicon oxide film 4,5, having a thickness of several hundred nm
6 and 7 are grown (the state obtained in this step is shown in FIG. 2). Next, the silicon polycrystal wafer 1 and the silicon single crystal wafer 2 obtained above are superposed on each other, and in this state, 7
Heat treatment is performed for several tens of minutes to several hours in an oxygen atmosphere of 00 to 1100 ° C. As a result of this heat treatment, the silicon oxide films 5 and 6 formed on the surfaces of the two wafers to be bonded are fused and the two silicon wafers 1 and 2 are welded (in the steps up to this point). The obtained semiconductor device is shown in FIG. The surface of the bonded SOI wafer on the silicon single crystal wafer 2 side (the side on which the silicon oxide film 4 is formed) is removed by polishing to an appropriate thickness, and then lapping / polishing is performed to form a semiconductor element. Make the surface a mirror surface. Then, the thermal oxide film 7 formed on the back surface side of the silicon polycrystalline wafer 1 is removed with an etching solution such as HF to form the SOI bonded wafer shown in FIG.

A silicon oxide film (5, 5) is formed on the bonding surfaces of the silicon polycrystalline wafer 1 and the silicon single crystal wafer 2.
In forming 6), silicon oxide may be grown by, for example, a chemical vapor deposition method (CVD method) instead of the thermal oxidation of the wafer surface as in the above embodiment.

As described above, in the above-described embodiment, two silicon wafers are bonded together via an insulating film to form an SOI.
In forming the bonded wafer, one of the silicon wafers was a silicon polycrystal wafer and the other silicon wafer was a silicon single crystal wafer. Therefore, the silicon on the surface and / or inside where the semiconductor element is formed is The wafer is a silicon single crystal wafer as before,
There is an effect that the total manufacturing cost can be reduced by the effect that a silicon wafer having a low manufacturing cost can be formed on the side where the semiconductor element is not formed (on the side of the supporting substrate).

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, as the insulating film formed on the bonding surfaces of the silicon polycrystalline wafer 1 and the silicon single crystal wafer 2, for example, nitride (Si ₃ N ₄ ) is used instead of the silicon oxide film (5, 6) shown in the embodiment. ) An insulating film such as a film (an insulating film having substantially the same coefficient of thermal expansion as a silicon wafer) may be formed.

In this embodiment, a silicon polycrystalline wafer, which has a low manufacturing cost, is used as the supporting substrate. However, instead of this, a silicon single crystal wafer which is regarded as a defective product in the LSI manufacturing process (for example, The manufacturing cost of the SOI bonded wafer may be reduced by using a wafer in which dislocations or the like have occurred during the manufacturing of single crystal silicon, a wafer which is determined to be defective during the LSI manufacturing process or after the manufacturing process is completed). Further, as an inexpensive silicon wafer used for the supporting substrate side, it is also considered that the growth condition of the silicon single crystal is relaxed and the manufacturing time of the ingot is shortened.

[0015]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows. That is, in the SOI bonded wafer, the manufacturing cost of the entire wafer can be reduced while the quality of the SOI wafer is substantially the same as that of the previous wafer.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of an SOI bonded wafer according to the present invention.

FIG. 2 is a partial cross-sectional view of two wafers before bonding showing a state in which silicon oxide is formed on the surfaces of a silicon single crystal wafer and a silicon polycrystalline wafer.

FIG. 3 is a sectional view of the wafer showing a state in which the two wafers shown in FIG. 2 are bonded together.

[Explanation of symbols]

 1 Silicon polycrystalline wafer 2 Silicon single crystal wafer 5,6 Silicon oxide film (insulating film)

Claims (3)

[Claims] 1. A semiconductor device in which two silicon wafers are bonded together via an insulating film, wherein one silicon wafer is a silicon polycrystalline wafer and the other silicon wafer is a silicon single crystal wafer. A semiconductor device characterized by. 2. The insulating film is made of a silicon oxide film,
The semiconductor device according to claim 1, wherein the silicon polycrystal wafer and the silicon single crystal wafer are bonded to each other by applying heat treatment. 3. A silicon polycrystal wafer or a silicon single crystal wafer, at least one surface of at least one of the wafers is oxidized, the oxidized surface is bonded to the other wafer, and a heat treatment is applied to this to bond the silicon polycrystal wafer. A method of manufacturing a semiconductor device, which comprises bonding a crystal wafer and a silicon single crystal wafer.