JPH04206925A - Manufacture of stuck wafer - Google Patents

Abstract

PURPOSE:To form a silicon single-crystalline thin film in the uniform thickness with good accuracy by forming a silicon oxide film on the whole surface of a principal plane of a first single-crystal silicon wafer on which recessed parts are formed partially and by making the silicon oxide film flat and then by sticking the first single-crystal silicon wafer and a second single-crystal silicon wafer having a flat principal plane together, the silicon oxide film-formed surface of the wafers facing each other. CONSTITUTION:A resist film 102 is partially formed on the surface of a single-crystal silicon wafer 101. Then, the wafer 101 is etched to form recessed parts on the wafer. Nextly, the resist film 102 is removed and the wafer is oxidized by thermal oxidation to form a silicon oxide film 103. After that, an organic coating 104 is formed on the silicon oxide film 103 and then dry etching is conducted for making the silicon oxide film 103 flat. Nextly, the above single-crystal silicon wafer and a single-crystal silicon wafer 105 which has a silicon oxide film 106 on the whole surface of its one face are stuck together, the silicon oxide film-formed surface facing each other. The thus obtained laminated single-crystal silicon wafer 101 is polished to form a single-crystal silicon thin film 107. At that time, the silicon oxide film 103 serves for a stopper which stops the progress of the polishing.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method of manufacturing a bonded wafer used for manufacturing semiconductor devices, and more specifically,
The present invention relates to a method for forming a silicon single crystal thin film having a thickness of 1100 nm or less, particularly 1100 nm or less.

(Prior Art) 11=Silicon single crystal wafers are widely used as substrate materials for semiconductor devices. This silicon single crystal wafer is generally manufactured through the steps shown below.

First, purified polycrystalline silicon is melted, and a single crystal seed is brought into contact with it to gradually grow it to create a silicon single crystal ingot. This silicon single crystal ingot is cut into a thickness of approximately several hundred μm. At least one of the cut silicon single crystal plates is polished to obtain a silicon single crystal wafer.

Using the wafer thus produced, seven different types of semiconductor devices are produced by performing processes for producing semiconductor devices, such as epitaxial growth, oxidation, diffusion, and vapor deposition.

For example, for semiconductor devices such as MOS-LSI, performance is improved by forming a semiconductor device on a single crystal film with good crystallinity on an insulating substrate or insulating film, since the junction capacitance can be reduced, rather than forming it on a silicon single crystal wafer. can be achieved. When manufacturing a semiconductor device using a silicon single crystal film on such an insulator, the silicon single crystal with good crystallinity must be uniformly processed into a film as thin as possible (approximately 1 μm or less in thickness). When this is used as a substrate, the electron movement speed increases in the resulting semiconductor device, and the electron movement speed becomes uniform, so that the operating speed is high and a large current can flow. Higher performance semiconductor devices are being developed.

Methods for producing such a silicon single crystal thin film include a growth method, a recrystallization method, and a bonding method. Among these, there is a growth method that grows a silicon single crystal thin film on an insulator such as a silicon oxide film.

The recrystallization method, which recrystallizes amorphous silicon by irradiating an energy beam onto an amorphous silicon film deposited on an insulator using the CVD method, has the drawback of high cost. It has the disadvantage that its crystallinity is inferior to that of silicon single crystal wafers.

On the other hand, in the bonding method, a silicon single crystal thin film is formed by polishing the silicon single crystal weno produced as explained above, which is relatively inexpensive and has good crystallinity. A silicon single crystal thin film having good crystallinity can be produced at low cost.

Manufactured using a bonding method. A wafer having a silicon single crystal thin film is called a bonded wafer. For example, one bonded wafer is manufactured as shown below.

FIGS. 2(a) to 2(c) are cross-sectional views showing a conventional method of manufacturing a bonded wafer.

First, as shown in FIG. 2(a), a silicon single crystal wafer 204 has a silicon oxide film 205 formed on its entire surface.
and a silicon single crystal wafer 201 are bonded together with the surfaces on which the silicon oxide film 205 is formed facing each other. As shown in FIG. 2(b), the silicon oxide sandwiched between the silicon single crystal wafers is A laminate having a film is formed. Next, by polishing one silicon single crystal wafer of the laminate.

A silicon single crystal thin film 207 is formed to obtain a bonded wafer.

Another example of how to create a bonded wafer is shown below.

FIGS. 3(a) to 3(c) are cross-sectional views showing another conventional method for manufacturing bonded wafers.

First, as shown in FIG. 3(a), a silicon single crystal wafer 304 having a silicon oxide film 305 formed on its entire surface, and another silicon single crystal wafer 301 having a silicon oxide film 308 formed over its entire surface. By bonding them together with their oxide/recon film-formed surfaces facing each other, as shown in Figure 3(b), a stack of silicon oxide films sandwiched between silicon single crystal wafers is formed. Form. Next, by polishing one silicon single crystal wafer of the laminate, a thin film 307 of Noricon single crystal is formed.
A bonded wafer is obtained.

(Problems to be Solved by the Invention) In these conventional methods for manufacturing bonded wafers, silicon is removed by polishing one silicon single crystal wafer of a stacked body having a silicon oxide film sandwiched between silicon single crystal wafers. A single crystal thin film is formed. When performing this polishing, the thickness of the silicon single crystal thin film is indirectly determined by monitoring the thickness of the silicon semiconductor wafer.

It is difficult to precisely polish the silicon single crystal wafer to a uniform thickness. Therefore, it is difficult to form a silicon single crystal thin film with a thickness of 1 μm or less with high precision, and even more so, it is virtually impossible to form a silicon single crystal thin film with a thickness of 1100 nm or less with high precision and uniform thickness. there were.

The present invention solves the above-mentioned conventional problems, and its purpose is to uniformly and accurately form silicon single crystal thin films with a thickness of 1 μm or less, and even silicon single crystal thin films with a thickness of 1100 nm or less. An object of the present invention is to provide a method for manufacturing a bonded wafer that can be formed to a certain thickness.

(Means for Solving the Problems) The present invention includes the steps of: forming a silicon oxide film over the entire main surface of a first silicon single crystal wafer in which recesses are partially formed; and flattening the silicon oxide film. the first step;
with silicon single crystal wafers.

and a step of bonding a second silicon single crystal wafer having a flat main surface with the surfaces on which the silicon oxide film is formed facing each other, thereby achieving the above object.

The planarization step is performed so as not to expose the main surface of the first silicon single crystal wafer.

Preferably, the second silicon/recon single crystal wafer has a silicon oxide film formed over its entire main surface to be bonded to the first silicon single crystal wafer.

(Function) Produced by the production method of the present invention. In a laminated body having an oxide/recon film sandwiched between silicon single crystal wafers, a silicon oxide film partially embedded in one silicon single crystal wafer is removed from the silicon oxide film to one silicon single crystal wafer. It is provided in a form that partially protrudes inside.

When a silicon single crystal thin film is formed by polishing a silicon single crystal wafer on which a silicon oxide film is partially provided in the above-mentioned laminate, silicon oxide is not substantially polished under the polishing conditions used in the present invention. Therefore, the progress of polishing is stopped at the partially provided silicon oxide film. As described above, according to the manufacturing method of the present invention, it is possible to accurately and uniformly form a silicon single crystal thin film to the thickness of a partially provided silicon oxide film.

(Example) An embodiment of the present invention will be described below.

FIGS. 1(a) to 1(1) are cross-sectional views showing the manufacturing process of a bonded wafer according to an embodiment of the present invention.

First, a silicon single crystal wafer lot shown in FIG.
A resist film 102 was partially formed on the surface of the substrate as shown in FIG. 2(b). Using this resist film 102 as a mask, the silicon single crystal wafer 101 is etched to a depth of 5, as shown in FIG. 1(C).
A recess of 0 nm was formed. Then, the resist film 10
After removing 2, the entire main surface of the silicon single crystal wafer 101 was thermally oxidized to form an oxide film 103 with a thickness of 500 nm as shown in FIG. 1(d). Thereafter, a resist or polyimide or the like is applied onto the silicon oxide film 103 to form an organic coating film 104, thereby obtaining a flat surface as shown in FIG. 1(e). From above, dry etching is performed under conditions such that the etching rate of the silicon oxide film 103 and the organic coating film are equal, as shown in FIG. 1(f).
The silicon oxide film 103 was planarized as shown in FIG.

Next, the silicon single crystal wafer and a silicon single crystal wafer 105 having a silicon oxide film 106 formed on the entire surface thereof as shown in FIG. 1(g) are placed so that the surfaces on which the silicon oxide film is formed face each other. By bonding them together, the result is as shown in FIG. 1(h).

A laminate having a silicon oxide film sandwiched between silicon single crystal wafers was obtained. At this time, 1: silicon single crystal weno with a silicon oxide film partially formed on the surface with a 1-inch silicon oxide film; 9: silicon single crystal weno with a silicon oxide film formed on the entire surface of the silicon oxide film: 105 After the surfaces on which the film was formed were electrostatically bonded together, the two wafers were bonded together by heat treatment.

Next, by polishing the silicon single crystal wafer 101 of the laminate thus obtained, a silicon single crystal thin film 107 with a thickness of 50 nm was formed as shown in FIG. 1 (1). Since the silicon oxide film 103 formed on the silicon single crystal wafer 101 in the process is not polished, it functions as a stopper to stop the progress of polishing.

In this way, a silicon single crystal thin film with a thickness of 50 nm could be formed uniformly and accurately.

In this example, a silicon single crystal thin film with a thickness of 50 nm was formed by forming a recess with a depth of 50 nm in the silicon single crystal wafer lO1. It is also possible to form a thick silicon single crystal thin film.

Furthermore, in this embodiment, the silicon oxide film 103 was formed using a thermal oxidation method, or it is also possible to form it using a vapor phase growth method.

Furthermore, in this embodiment, an example in which a silicon oxide film is formed on the main surface of the second silicon single crystal wafer has been described, but a second silicon single crystal wafer on which a silicon oxide film is not formed is used. A similar result was obtained.

The silicon oxide film 103 left on the bonded wafer manufactured by the manufacturing method of the present invention can be used as it is as a semiconductor element isolation region.

(Effects of the Invention) As described above, in the manufacturing method of the present invention, the silicon oxide film functions as a polishing stopper when polishing a silicon single crystal wafer. therefore.

It is possible to produce a bonded wafer in which a silicon single crystal thin film having a thickness of 1100 nm or less is formed with high precision and uniform thickness.

4.'. Figures 1(a) to (i) are cross-sectional views showing the manufacturing process of a bonded wafer according to an embodiment of the present invention, and Figures 2(a) to (i) are simple cells.
c) is a sectional view showing a conventional example of a method for producing a bonded wafer, and FIGS. 3(a) to 3(c) are sectional views showing other conventional examples of a method for producing a bonded wafer.

101, 105.201.204.301.304...
・Silicon single crystal Uniha, 103.106.205,3
05.308...Silicon oxide film, 107°207
．． 307...Silicon single crystal thin film.

that's all

Claims (1)

[Claims] 1. Forming a silicon oxide film over the entire main surface of a first silicon single crystal wafer in which recesses are partially formed; Planarizing the silicon oxide film; manufacturing a bonded wafer comprising: bonding a first silicon single crystal wafer and a second silicon single crystal wafer having a flat main surface with their surfaces on which silicon oxide films are formed facing each other; Method.