JPH02237032A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To form a device region developing the least crystalline defect for bearing the excellent characteristics by a method wherein one conductivity type impurity diffused layer is formed on the surface of the first semiconductor substrate; gettering windows are selectively made in the part of the insulating film (impurity diffused layer); and then the device is formed in the second semiconductor layer in the same conductivity as that of the impurity diffused layer. CONSTITUTION:A polysilicon layer 12 is formed e.g. on the first p type silicon wafer 11 and then p<+> type layer 13 is formed by ion-implanting boron. The polysilicon layer 12 is selectively etched away to leave the polysilicon making gettering windows 14 but at this time, a p<+> type impurity diffused layer 13a is left without being etched away on the surface of the silicon wafer 11. Next, the whole surface is coated with a spin on glass(SOG) 15 by flattening process and then the SOG 15 on the silicon wafer 11 is heat-treated for flattering and thinning processes to form the second silicon layer 16 for device formation. Finally, a specified device 18 is formed in the region encircled by SiO2 layers 17 and connecting to the gettering windows 14. Through these procedures, any crystalline defect can be obviated to enhance the device characteristics.

Description

[Detailed Description of the Invention] [Summary] Regarding a semiconductor device and its manufacturing method, particularly a method of manufacturing a silicon-on-insulator (SOI) substrate using an adhesive technology, this problem occurs in the process of forming a device on an SO1 substrate using a conventional adhesive technology. In a silicon-on-insulator structure formed by adhesion, the surface of a first semiconductor substrate is one conductive. A type of impurity diffusion layer, on which a semiconductor gettering window is selectively provided on a part of the insulating film and flat with it, and has the same conductivity as the impurity diffusion layer bonded on the insulating film. A semiconductor device is characterized in that a device is formed on a second semiconductor layer of a mold, and a semiconductor layer is formed on a first semiconductor substrate, and an impurity of one conductivity type is diffused through the semiconductor layer. forming an impurity diffusion layer on the surface of the semiconductor substrate; forming an insulating film on the semiconductor layer to be flat with the gettering window where the insulating film (15) is selectively formed; and forming a second insulating film on the insulating film. A method for manufacturing a semiconductor device comprising the steps of: forming a semiconductor layer, and forming a device in the semiconductor layer connected to the gettering window and surrounded by an element isolation layer. [Industrial Application Field] The present invention relates to a semiconductor device and a method for manufacturing the same, and particularly to a method for manufacturing a silicon-on-insulator (501) substrate using adhesive technology.

[Conventional technology]

SOI substrates manufactured using adhesive technology are attracting attention as being suitable for high-speed LSIs and VLSIs because of their good crystal orientation and interface characteristics, which prevent latch-up, have excellent radiation resistance, and allow thin device fabrication layers. Current LSIs are strongly required to have high integration and high speed. SOI devices have been proposed to meet these demands, and bonding technology is an effective means of realizing SO1 substrates (wafers) used in these devices. SO! The substrate is being studied.

Furthermore, according to the above-mentioned technology, it is possible to reduce the thickness of the semiconductor layer that forms the device region, which reduces leakage current and is expected to improve performance during high-temperature operation. 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. FIG. 3 is a cross-sectional view illustrating a conventional method for forming a So1 substrate by adhesion. First, as shown in FIG. 3(a), a first silicon wafer 31 is coated with a Sin. The second silicon wafer 32 on which the film 33 is formed is coated with a Sing film 33.
is bonded in contact with the first silicon wafer 31. Next, as shown in Φ) in the same figure, the second silicon wafer 3 is
2 to Sin. The back surface where the film 33 is not formed is polished to leave a silicon layer 34 having a thickness of, for example, about 10 μm and serving as a device formation area. 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 ICs, we have to deal with intrinsic impurities and defects in the materials, as well as process problems. induced during,
It is necessary to efficiently remove or erase 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 any crystal defects cause deterioration of device characteristics.

Referring again to FIG. 3(C), the silicon layer 34, which is the device formation region, is completely separated from the underlying silicon wafer 31 by the underlying SiO2 film 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 an SOI structure that can getter-isolate crystal defects that occur in the process of forming devices on an SO1 substrate using conventional bonding techniques, and a method for forming such a structure. [Means for solving the problem] The above problem is that in the silicon-on-insulator structure formed by adhesion, the surface of the first semiconductor substrate is an impurity diffusion layer of one conductivity type, and the impurity diffusion layer is formed on the impurity diffusion layer. A semiconductor gettering window is selectively provided in a part of the insulating film and flat with it, and a device is formed in a second semiconductor layer of the same conductivity type as the impurity diffusion layer bonded on the insulating film. A semiconductor device characterized by: forming a semiconductor layer on a first semiconductor substrate; diffusing an impurity of one conductivity type through the semiconductor layer to form an impurity diffusion layer on the surface of the wafer; forming an insulating film flat with the gettering window in which the insulating film (15) is selectively formed, and forming a second semiconductor layer on the insulating film, connected to the gettering window and forming an element. The problem is solved by a method for manufacturing a semiconductor device, which includes a step of forming a device in the semiconductor layer surrounded by a separation layer.

[Effect]

Crystal defects in semiconductors are caused by impurities such as metal, so removing this metal contamination from the device active region is an effective factor in improving device characteristics. Since these metal impurities have the characteristic of being more likely to gather in areas where there are crystal defects, we focused on the fact that it is sufficient to provide areas where there are crystal defects apart from the device formation region.

For this purpose, a high concentration (N=10
” / cd) p-type region by boron doping?
Gettering is performed by
988 Autumn Na7a-X-5). Such p+ region 3
7 is formed under the Sing film 33 as shown in FIG. Silicon layer 34 which is a formation region
gettering of metal contamination.

That is, in the present invention, in a part of the SiO film having the Sol structure,
Silicon area (region where polysilicon is embedded) where the underlying silicon wafer and device formation area are connected
By forming this, defects or metal impurities generated or present during the device fabrication process are gettered, thereby forming a device region with few crystal defects and achieving good characteristics.

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

FIG. 1 shows a cross-sectional view of an embodiment of the present invention.

See FIG. 1(a): A semiconductor substrate to which a device-forming semiconductor layer is attached is prepared. As a substrate, a semiconductor layer, that is, a polysilicon layer 12 is formed to a thickness of 1 μm on a first silicon wafer l1 of, for example, p-type, lOΩ·1, by, for example, the CVD method. When the silicon wafer to be attached to the semiconductor substrate in the next step is made to be of p-type, boron ions of the same conductivity type (p-type) are implanted into 1019/cJ shown with diagonal lines in the figure.
A P layer 13 having a concentration of about 100% is formed.

Refer to FIG. 1(b): Selectively form an insulating film (15) on the polysilicon Jlil2.
The polysilicon that will become the gettering window 14 is left. 4, the p+ impurity diffusion layer 13a remains on the surface of the silicon wafer 11 without being etched. Next, spin-on glass (S), which becomes an insulating film, is applied by spin coating the entire surface.
OG) 15 is applied to a thickness of 2 μm and flattened. This planarization is performed by polishing the SOG after it dries until the polysilicon that will become the gettering window 14 is exposed.

? See Figure 1 (C): A silicon wafer is bonded together as a P-type second semiconductor layer for device formation, heat treated at 1000°C for 30 minutes, and this silicon wafer is polished to a thickness of 0.5 μm. Planarization and thinning are performed to form second silicon N16 for device formation.

See Figure 1(d): For example, SiOJ for element isolation using selective oxidation! 17 is formed on the silicon layer l6. Since the silicon layer 16 has a thickness of about 0.5 .mu.m, there is no particular problem in forming the SiO2M layer 17. Next, a desired device 18 is formed in a region surrounded by the SiO2 layer 17 and connected to the gettering window 14. In the SOI with one structure, defects generated in the manufacturing process of the device 18 and defects originally existing in the silicon Jil 6 pass through the gettering window 14 of polysilicon to the p-type on the surface of the silicon wafer 11. The impurity is gettered in the impurity diffusion layer 13a, and a device 18 with good characteristics is formed. [Effects of the Invention] As described above, according to the present invention, gettering of defects caused by metal impurities in the SOI structure is performed during device formation, and as a result, gettering of defects caused by metal impurities in the SOI structure is performed, and as a result, gettering of defects caused by metal impurities etc. in the SOI structure is performed. It is possible to simultaneously remove defects that have occurred and those that already existed, thereby improving device characteristics.

[Brief explanation of drawings]

Figures 1 (a) to (d) are cross-sectional views of embodiments of the present invention, Figure 2 is a cross-sectional view explaining the principle of the present invention, and Figures 3 (a) to (C).
is a sectional view of a conventional example. In the figure, 11 is a first silicon wafer (semiconductor substrate), 12 is a polysilicon layer (semiconductor N), 13 is a p0 layer, 13a is a p+ type impurity diffusion layer, 14 is a gettering window, and 15 is a spin-on layer.・Glass, 16 is the second silicon layer (semiconductor layer), 17 is Sing
layer (element isolation layer), 18 indicates a device.

Claims (2)

[Claims] (1) In the silicon-on-insulator structure formed by adhesion, the surface of the first semiconductor substrate (11) is an impurity diffusion layer (13a) of one conductivity type, and an insulating layer is formed on the impurity diffusion layer (13a). A semiconductor gettering window (14) is selectively provided in a part of the film (15) and flat with it, and the impurity diffusion layer (13) is bonded on the insulating film (15).
A device (
18) A semiconductor device comprising: (2) A semiconductor layer (12) on the first semiconductor substrate (11)
gettering formed by forming an impurity diffusion layer on the surface of the semiconductor substrate (11) by selectively etching the semiconductor layer (12) by diffusing impurities of one conductivity type through the semiconductor layer (12); A step of forming an insulating film (15) flat with the window (14), and forming a second semiconductor layer (16) on the insulating film, connected to the gettering window (14) and forming an element isolation layer. (
A device (1) is placed within the semiconductor layer (16) surrounded by
8) A method for manufacturing a semiconductor device, comprising the step of forming.