JPH0448618A - Manufacture of semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Summary) Regarding the improvement of the method for manufacturing 301 (silicon-on-insulator) substrates, a Sol. The purpose of the present invention is to provide a method for manufacturing a bonded SOI substrate that enables manufacturing without introducing defects and contaminants into the substrate, and the semiconductor wafer on the element forming side and the semiconductor wafer on the support side are bonded via an insulating film. In the method for manufacturing a semiconductor device 1, which includes the step of polishing the semiconductor wafer on the element forming side to reduce its thickness, a circular semiconductor wafer is used as at least the semiconductor wafer on the supporting side; The structure is such that an orientation layer is formed after adhering to the semiconductor wafer on the element formation side.

[Industrial application field]

The present invention relates to an improvement in a method for manufacturing a 5ol (silicon-on-insulator) substrate.

[Conventional technology]

After overlapping two silicon wafers with oxide films formed on their surfaces, they are bonded together by heat treatment, and then
On the other hand, the so-called bonded SO■ substrate, which is manufactured by thinning Noricon wafers, is superior in terms of improved integration, faster device characteristics, and improved radiation resistance when used as an LSI substrate. The present invention, which achieves the above results, relates to an improvement in the manufacturing method of this bonded Sol substrate.

A conventional method for manufacturing an SO2 substrate will be explained with reference to FIG. First, as shown in the same figure (a), two silicon wafers 2 on which orientation flats are formed are
After mirror-finishing the surfaces of each and oxidizing one silicon wafer, for example, silicon wafer 1 to form a silicon dioxide film 3 on the surface, as shown in FIG.
As shown in FIG. 4(C), they are overlapped and annealed at a temperature of 900° C. to 1.000° C. to bond them together. The tensile strength of the adhesive surface at this time is approximately 2,000
g/cm", and will not peel off during the subsequent semiconductor device manufacturing process.

Next, as shown in FIG. 4D, the surface of one silicon wafer 1 is ground and further polished by about 1n to remove surface defects and to reduce the thickness to about 5n. Elements are formed on this thinned silicon layer.

[Problems to be Solved by the Invention] In a bonded SOI substrate, the thinner and more uniform the silicon layer on the element formation side, the better the device characteristics after the element formation, and the easier it is to separate the elements. . Therefore, how to make the silicon layer on the element formation side uniform and
The central issue in the development of Sol substrates is how to form them thinly. 6-inch S manufactured using conventional methods
In the OL substrate, the thickness of the thinned silicon layer on the element forming side is about 5n, and the variation in film thickness is about 2n in the plane. This variation in film thickness is
Variation in thickness of supporting side silicon wafer of bonded SOI substrate (TTV; Total Thickne
This is due to the fact that there are 2 to 3n of ss Variations).

When polishing both sides of a circular wafer without an orientation flat, thickness variation (TTV) occurs.
It is known that good wafers with a diameter of about 0.8n can be produced. However, for use in manufacturing semiconductor devices, an orientation flat must be formed.

Polishing both sides of a circular wafer to check thickness variations (TTV)
) If an orientation flat is formed after forming a wafer with a small amount of When chamfering a portion, defects may be introduced to the supporting wafer surface or contaminants may adhere to the surface. If the 501 substrate is manufactured by adhering to the element formation side wafer with defects introduced into the surface of the supporting side wafer or contaminants attached, it may cause deterioration of device characteristics after the element fabrication. Become.

The purpose of the present invention is to eliminate this drawback, and to prevent defects and contaminants from being introduced into the bonding interface of an SO2 substrate, in which the thickness of the semiconductor layer on the element formation side is thin and there is little variation in film thickness. An object of the present invention is to provide a method for manufacturing a bonded SOr substrate that allows manufacturing without any problems.

[Means to solve the problem]

The above purpose is to bond the element forming side semiconductor wafer (1) and the supporting side semiconductor wafer (2) via an insulating film (3), and polish the element forming side semiconductor wafer (1) to increase its thickness. In the method of manufacturing a semiconductor device, the method includes a step of reducing the thickness of at least the support side semiconductor wafer (2).
) is achieved by a method of manufacturing a semiconductor device in which a circular semiconductor wafer is used and an orientated silane flat (4) is formed after bonding it to the semiconductor wafer (1) on the element formation side.

[Effect]

In the method for manufacturing an SO2 substrate according to the present invention, a supporting side semiconductor wafer with less thickness variation (TTV) is produced by polishing both sides of a circular semiconductor wafer on which no orienting silane flat is formed. Since the element forming side semiconductor wafer is bonded, variations in film thickness of the element forming side semiconductor wafer are reduced. Moreover, since the orientation flat of the supporting semiconductor wafer is formed and chamfered after bonding, there is no possibility of introducing defects or adhering contaminants to the bonding surface.

Even if defects or contaminants occur on the surface of the semiconductor wafer on the element formation side when creating the orientation flat after adhesion or when chamfering the orientation flat, there will be no problem as it will be removed by grinding and polishing in the subsequent thinning process. do not have.

〔Example〕

Hereinafter, with reference to the drawings, a So
A method for manufacturing the l-substrate will be explained.

Refer to FIG. 1. As shown in FIG. 1(a), the surfaces of the element-forming side silicon wafer 1 on which the orientation flat is formed and the circular supporting side silicon wafer 2 are mirror-finished.

As shown in the figure (b), the surface of the silicon wafer 1 on the element formation side is thermally oxidized to form a silicon dioxide film 3 with a thickness of 1 to 2 nm.
form.

As shown in FIG.
Heat treatment is performed at a temperature of 00°C to 1,000°C to bond the two together.

As shown in FIG. 2D, an orientation flat is formed on the supporting silicon wafer 2 using a dicer, and chamfer polishing is performed.

By the way, if a semiconductor device is fabricated on an SOI substrate and is then fully cut and separated into chips, there is no need to specify the direction of the orientation flat of the supporting silicon wafer 2, but when it is half-canted and separated into chips, Since it is necessary to set the plane orientation of the orientation flat to +1101, a mark indicating the orientation is placed on the side surface of the supporting silicon wafer 2 in advance.
It is necessary to overlap and bond the silicon wafer 1 on the element forming side so that the orientation flat of the silicon wafer 1 corresponds to that position.

Note that a circular silicon wafer is also used for the element formation side silicon wafer 1, and a circular silicon wafer 2 is used for the support side.
After adhering to the substrate, orientation flats may be formed on both at the same time. However, when half-cutting and cutting into chips after semiconductor device fabrication, the element forming side silicon wafer 1 and the supporting side silicon wafer 2 are overlaid and bonded so that their orientations match, and the orientation is aligned to the N101 plane. Make sure to form a flat.

Next, as shown in FIG. 4(e), the element forming side silicon wafer 1 is ground and further polished to a thickness of about 1n to make it a thin film.

See Fig. 2 Fig. 2 shows the thickness variation (TTV) of the supporting wafer 2.
) and the variation in film thickness of the element-forming wafer 1 after polishing, which is a graph obtained through experiments. When the method of the present invention is used, the thickness variation (TTV) of the supporting wafer 2 is about 0.8n, which is lower than the conventional value (2~
3n), and as is clear from FIG. 2, the variation in film thickness on the element forming side wafer 1 is reduced to less than half of the conventional variation, and in response, The film thickness of the wafer 1 becomes Fj.

〔Effect of the invention〕

As explained above, in the method for manufacturing a semiconductor device according to the present invention, both sides of a circular semiconductor wafer are polished to produce a support side semiconductor wafer with less variation in thickness, and this is bonded to an element forming side semiconductor wafer. So,
Variations in the film thickness of the semiconductor wafer on the element formation side are reduced, and in response to this, it becomes possible to reduce the film thickness of the semiconductor wafer on the element formation side. In addition, after the circular supporting semiconductor wafer and the element-forming semiconductor wafer are bonded together, an orientated silane flat is formed on the supporting semiconductor wafer, which may introduce defects or contaminants into the bonding interface between the two. This S
Deterioration of device characteristics when a semiconductor device is formed on the o1 substrate does not occur.

[Brief explanation of drawings]

FIG. 1 is a process diagram for manufacturing an SOI substrate according to an embodiment of the present invention. Figure 2 shows the thickness variation (TTV) of the supporting wafer.
FIG. 4 is a diagram showing the relationship between the thickness of the wafer and the variation in film thickness of the wafer on the element forming side. FIG. 3 is a process diagram for manufacturing an SO2 substrate according to the prior art. DESCRIPTION OF SYMBOLS 1... Element formation side semiconductor wafer, 2... Supporting side semiconductor wafer, 3... Insulating film, 4... Orientation flant.

Claims (1)

[Claims] An element forming side semiconductor wafer (1) and a supporting side semiconductor wafer (2) are bonded via an insulating film (3), and the element forming side semiconductor wafer (1) is polished to reduce its thickness. In the method for manufacturing a semiconductor device including a step of reducing the thickness, a circular semiconductor wafer is used as at least the supporting side semiconductor wafer (2), and after being bonded to the element forming side semiconductor wafer (1), an orientation flat ( 4) A method for manufacturing a semiconductor device, characterized by forming.