JPH02237121A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To getter a crystal defect which is produced in a process to form a device on a bonded substrate by a method wherein parts connected directly by silicon are formed between silicon-on-insulator(SOI) bonded wafers. CONSTITUTION:An SiO2 film and an Si3N4 film as oxidation-resistant films are deposited one after another on a first silicon wafer 11; SiO2 layers 12 to be used as insulating layers are formed of them in a separated manner. Then, the surface is flattened; a second silicon wafer 13 as a CZ wafer of a high oxygen concentration is bonded; this assembly is heated; islands of the SiO2 layers 12 are formed between the silicon wafers 11, 13. Accordingly, the first and second semiconductor substrates are connected directly between the islands of the layers 12. Thereby, a detect of the second semiconductor substrate is gettered to the inside of a defect layer 14; the second semiconductor substrate becomes a defect free zone 15.

Description

[Detailed Description of the Invention] [Summary] A method for manufacturing semiconductor devices, especially silicon
The present invention relates to a method for manufacturing an on-insulator (SOI) substrate, and an object of the present invention is to provide a method for forming an SOI structure that can getter crystal defects that occur during the process of forming devices on an SOI substrate using conventional bonding techniques. forming insulating layers selectively separated from each other on a first semiconductor substrate; planarizing the surface of the first semiconductor substrate to form islands of the insulating layer embedded in the substrate; A method characterized by including the step of bonding a second semiconductor substrate to the surface of the first semiconductor substrate via the insulating layer, and forming a semiconductor device on the second semiconductor substrate above the island of the insulating layer. The present invention includes a method for manufacturing a semiconductor device.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for manufacturing a silicon-on-insulator (Sol) substrate using adhesive technology. [Conventional technology] SOT substrates made using adhesive technology are attracting attention as they are suitable for high-speed LSI and VLSI due to their good crystal orientation and interface characteristics, do not cause latch-up, have excellent radiation resistance, and have thin device fabrication layers. ing. Current LSIs are strongly required to have high integration and high speed, and the Sol device has been proposed as a device that satisfies this demand, and adhesive technology is an effective means of realizing the SO1 substrate (wafer) used for this device. SO1 substrates are being researched.

Further, according to the above-mentioned technology, since the semiconductor layer forming the device region can be made thinner, leakage current can be reduced, and performance improvement during high-temperature operation is expected. Another advantage is that almost all conventional LSI processes and device technologies can be used as is.

Note that conventional bonded SOI substrates have been made by simply bonding wafers whose surfaces have been oxidized. Figure 2 shows the method of forming an SOI substrate using conventional adhesion. In the cross-sectional view to be explained, first, as shown in FIG.
is bonded in a state where it is in contact with the first silicon wafer 3l.

Next, as shown in FIG. 3B, the second silicon wafer 32 is polished from the back side where the Sint film 33 is not formed, leaving a silicon layer 34 that will become a device formation region with a thickness of, for example, about 10 μm. . Note that in the figure, 36 is an insulating film.

Subsequently, a desired device 35 (for example, a MOS transistor) is formed on the silicon layer 34 as shown in FIG. 3C.

[Problem to be solved by the invention]

Currently, when manufacturing large-scale RC, it is necessary to avoid the inherent impurities and defects of the material, as well as the defects induced during the process.
It is necessary to efficiently remove or erase the introduced defects. This involves intrinsic gettering (I
Gettering of defects called G) is effective, and gettering is performed by heat treatment, for example.

Since the SO1 substrate according to the prior art is performed before the device region is manufactured, crystal defect reduction, that is, gettering is performed before the device manufacturing. Therefore, even if crystal defects occur during device fabrication, the Sin. Since the film 33 acts as a so-called buffer and effective gettering cannot be performed on it, there is a problem in that some crystal defects cause deterioration of device characteristics.

Referring again to FIG. 2(C), the silicon layer 34, which is the device formation region, is formed by the underlying Sin. It is completely separated from the underlying silicon wafer 31 by a membrane 33.

For this reason, for the occurrence of crystal defects during device formation, gettering processing can only be performed within a range limited by the device formation process conditions. For example, intrinsic gettering (IG) requires heat treatment at high temperatures and for a long period of time, which cannot be matched with the device formation process. In this sense, it is difficult to reduce crystal defects caused by device formation in the conventional Sol structure, leading to deterioration of device characteristics.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for forming an SOI structure that can getter crystal defects that occur in the process of forming devices on an SOIi plate using conventional bonding techniques.

[Means for Solving the Problems] The above problems include a step of forming selectively separated insulating layers on a first semiconductor substrate, a step of flattening the surface of the first semiconductor substrate, and forming a shape embedded in the substrate. forming an island of the insulating layer, bonding a second semiconductor substrate to the surface of the first semiconductor substrate via the insulating layer, and attaching a semiconductor device to the second semiconductor substrate above the island of the insulating layer; The problem is solved by a method for manufacturing a semiconductor device characterized by including a step of forming a semiconductor device.

[Function] Is there an internal defect layer on the surface of the semiconductor substrate used to manufacture ICs? In order to produce a gettering effect, it is necessary to partially connect the upper and lower bonded wafers with silicon. Therefore, in the present invention, a buried SiO2 layer is partially formed using a selective oxidation method (LOCOS method), this is planarized, and the upper and lower wafers are then bonded to enable intrinsic gettering.

That is, in the present invention, by creating a directly connected portion with silicon between the SOI bonded wafers, the silicon precipitate layer formed in the substrate exhibits a gettering effect during the process.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

FIG. 1 is a sectional view showing an embodiment of the present invention.

Refer to FIG. 1(a): For example, an oxidation-resistant film (not shown) is formed on a first semiconductor substrate (silicon wafer) having a thickness of 600 to 700 μm.
00 to 1000 film thickness Sin. membrane and 1,00
0~? , 500-thick Si3N. After sequentially depositing these films and patterning these films, SiO2N12, which will become an insulating layer, is formed by, for example, a wet oxidation method. S
tOzN■ The distance di between the two is 10 μm, and the SiOJ
The above-mentioned oxidation-resistant film is buttered so that each extension d2 of I2 is 20 μm.

See Figure 2 Φ): Apply a resist (not shown) with the same selectivity as SiOz over the entire surface, and perform anisotropic etching to etch the resist and Sing to flatten the surface. Refer to FIG. 1(C): A second semiconductor substrate (silicon wafer) 13, which is a CZ wafer with a high oxygen concentration, is bonded and heated to form an island of SiO layer 12 between silicon 11 and silicon 13. Form into. To do this, for example, a 200 μm wafer is prepared as the second silicon wafer, and then a 30 to 50 μm wafer is prepared.
Polishing is performed until a second silicon substrate 13 with a thickness of .

See Figure 1(d): ? An SOI device is formed on the SiO2 layer of the silicon substrate 13 of No. 2. When heat treatment is performed in the state shown in FIG. 14 is formed, and the second silicon substrate becomes a denuded zone 15 free of defect layers.

In other words, in the conventional method, a Sin2 film existed between the first and second silicon wafers, and the defect layer that occurred when forming devices on the second silicon wafer remained on the second silicon wafer. , In the structure shown in FIG. 1(d), between the islands of SiOJ'fil2, the first and second
Since the two silicon wafers are directly connected to each other, defects in the second silicon wafer are gettered into the I6 defect layer 14, and the second silicon wafer becomes a defect-free denuded silicon wafer.
zone 15, and the characteristics of devices formed there are improved.

〔Effect of the invention〕

As described above, according to the present invention, the rG effect occurs in the conventional Sol bonded wafer, and it becomes possible to remove defects and impurities (metal, etc.) created during the IC forming process.

[Brief explanation of drawings]

Figures 1 (a) to (d) are cross-sectional views of embodiments of the present invention, and Figure 2 (
a. ) to (C) are sectional views of conventional examples. In the figure, 11 is a first silicon substrate, 12 is a SiOz layer, 13 is a second silicon substrate, 14 is an IC defect layer, and 15 is a denuded zone.

Claims (1)

[Claims] A step of forming insulating layers (12) selectively separated from each other on a first semiconductor substrate (11), planarizing the surface of the first semiconductor substrate (11) and
1) forming an island of the insulating layer (12) embedded in the second semiconductor substrate (13) on the surface of the first semiconductor substrate (11) via the insulating layer (12); Glue the insulating layer (1
2) A method for manufacturing a semiconductor device, comprising the step of forming a semiconductor device on a second semiconductor substrate above the island.