JPS60147129A - Manufacture of dielectric insulated and isolated substrate - Google Patents

Abstract

PURPOSE:To produce the titled dielectric insulated and islated substrate with island type single crystal regions subject to different depth and high precision by a method wherein the first etching mask film and the second etching mask film made of different material are laminated to be utilized as successive etching mask for etching operation. CONSTITUTION:The first etching mask film 11 is formed on a single crystal silicon substrate 1 to make openings. The second etching mask film 12 is formed by means of photoetching process so that the film 12 may be composed of a coated part to produce the second shallow etching surface with openings corresponding to the first film 11 and specified depth. Then the substrate 1 is etched to provide the openings with specified depth. Next the second film 12 is removed utilizing acid without doing damage to the first film 11. Then anisotropic etching process is repeated. Later after removing the first etching mask 11, a dielectric film 7 is formed to be coated with polycrystalline silicon 8 as a supporter. Thus island type single crystal regions with different depth may be produced by means of parallel grinding operation.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to semiconductor integrated circuits, and particularly to semiconductor integrated circuits that require high breakdown voltage.

The present invention relates to a method for manufacturing an electrically insulated separation substrate.

Conventionally, this type of dielectric isolation substrate has a structure in which the supporting body has island-like single crystal silicon regions all made at the same depth, so that low breakdown voltage elements included in semiconductor integrated circuits However, since it is made in an island-shaped single crystal silicon chain plate with the same size as the high voltage element, the device size increases and the manufacturing cost becomes expensive. It has been considered to create a silicon region and a relatively shallow island-like single crystal silicon region within the same substrate. That is, the first
Figures (a) to (e) are cross-sectional views showing a method for manufacturing such a semiconductor device. First, as shown in Figure 1(a),
An etching mask film 2 is formed on a single crystal silicon substrate 1, a wide groove 3 is formed by etching as shown in () in the same figure, and a new mask film is then deposited on the bottom of the groove 3 as shown in (C) in the same figure. 4, and grooves 5 and 6 are formed by etching. Then, as shown in FIG. 1(d), the grooves 5 and 6 are
After covering the surface of the substrate on which is formed is an inhibiting five-layer film 7, polycrystalline silicon 8 is deposited, and then the surfaces of the single crystal substrate 1 and polycrystalline silicon 80 are polished. ), which is supported by a support of polycrystalline silicon 8 and has shallow island-like single-crystal silicon regions 9, 9 and deep island-like regions 10, which are separated into islands by a dielectric film 7. However, this conventional method has the drawbacks of lower yields due to misalignment of the metal fittings, and higher costs due to the complicated process. .

No. 1 Object of the Invention The present invention provides a dielectric comprising a highly precise deep island-like single crystal silicon region and a shallow island-like single crystal silicon region.

The purpose is to easily and inexpensively manufacture a salary edge separation board.

20 Structure of the Invention According to the present invention, a first etching mask film is formed on a single-crystal silicon substrate, and a wide opening for a shallow etching surface of the first mask film is closed, and a deep groove left behind is removed. A second etching mask film with matching openings for etching is formed over the first etching mask group, and after etching the silicon substrate using the second mask film as a mask,
The etching mask film is removed, etching is performed using the remaining first etching mask group as a mask, a dielectric film is formed on the surface of the silicon substrate after this etching, and a polycrystalline silicon support is formed on the dielectric film. A method of manufacturing a dielectric isolation isolation substrate is provided that includes depositing and then polishing.

E. Example 2 Next, the present invention will be explained using examples.

FIGS. 2(a) to 2(a) are cross-sectional views in the order of steps for explaining one embodiment of the present invention. As shown in FIG. 2(a), a first etching mask is formed on single crystal silicon. A film 11 is formed, and an opening is formed using photolithography, which is generally known as a method for manufacturing semiconductor integrated circuits.

In etching to obtain deep grooves in single-crystal silicon 1, Ishikawa uses the anisotropy due to the crystal plane of single-crystal silicon as an etching agent, and fCKOI (an aqueous solution is often used. The first etching mask film 11 may be a film obtained by thermally oxidizing the single crystal silicon 1, and a commonly known hydrofluoric acid aqueous solution may be used to create the openings by photoetching.

Next, a second etching group 12 is formed on the first etching mask film 11. As this second mask film,
For example, a well-known metal film such as nickel or chromium can be used. Using metals such as chromium,
In photo-etching to create openings, it is possible to etch with acids such as nitric acid; most acids hardly attack silicon and silicon oxides, and chromium films are sufficiently resistant to KOH aqueous solutions. . The second etching mask family 12 is photo-etched to consist of openings coinciding with the first etching mask membrane 11 and a covering to obtain a second shallow etched surface at the desired depth. Make it. After etching, as shown in &2iI(b), KOI (for example, an aqueous solution) is etched on the exposed portion of the single crystal silicon l to a predetermined depth of Pfr.The predetermined etching depth is completed. The layer height is determined by the depth of the shallow etched surface of the substrate.

Next, the second etching mask film 12 is removed using the aforementioned acid without removing the first etching mask film 11, thereby obtaining the cross-sectional structure shown in FIG. 2(C). When the monocrystalline silicon 1 is etched again by anisotropic etching, the structure differs from that shown in the second printing (d). After that, the first etching mask film 11 is removed,
Further, in order to form a dielectric insulating isolation substrate for use in a semiconductor integrated circuit, polycrystalline silicon 8 as a support is attached on top of the dielectric film 7 shown in FIG. 2(e). The dielectric film 7 is 5i obtained by thermally oxidizing single crystal silicon l.
It may be an Oz film or a film deposited by vapor phase growth or the like. To achieve the structure shown in Figure 2(f),
By polishing the monocrystalline silicon 1 and the polycrystalline silicon 8 parallel to each other, a dielectric insulation isolation structure in which island-shaped single crystal regions with different depths are embedded in the support, which is the object of the present invention, can be obtained. Substrates can be easily obtained. When realizing a semiconductor integrated circuit including a high breakdown voltage element using this type of dielectric film/edge separation substrate, a frost-conducting high concentration layer 13 identical to the single crystal silicon 1 shown in FIG. However, it is possible to easily form it by a commonly used diffusion method after removing the first etching mask film 11 shown in FIG. 2(d).

Effects of the Invention As described above, in the present invention, a first etching mask film and a second etching mask film made of a material different from that of the first etching mask film are used.
By overlapping these etching mask films and performing etching as a ti-th etching mask, it is possible to manufacture at low cost a dielectric insulating isolated substrate having highly precise island-shaped single crystal silicon regions having different depths.

[Brief explanation of the drawing]

Figures 1 (a) to (e) are cross-sectional views of the process order for explaining the conventional method of manufacturing a dielectric insulation isolation substrate, and Figure 2 (a)
-(f) are cross-sectional views in the order of manufacturing steps of an embodiment of the present invention. 1... Single crystal silicon substrate, 2, 4...
・Etching mask, 3... Wide opening, 5.
...Shallow groove, 6...Deep groove, 7...
・・Dielectric film, 8・・・・−・Polycrystalline silicon, 9・・
...Shallow island-like single crystal silicon region, 10...
・Deep island-like single crystal silicon region, 11...1st
etching mask film, 12... second etching mask film, 13... high concentration diffusion attraction.

Claims (1)

[Claims] After etching the surface of the single-crystal silicon substrate into a desired shape, the surface is covered with a dielectric film, and a support material is further deposited so that islands of the dielectric film are mutually supported by the layer of support material. In a method of manufacturing a dielectric insulating isolated substrate having a large number of island regions for forming isolated elements, a first etching mask film having a deep groove and an opening for obtaining a shallow etched surface is formed on the surface of the single crystal substrate. “The process of
and forming an M2 etching mask group on the first etching mask film, which aligns the opening of the mask film for the search groove and closes the opening for the shallow etching surface; Second etching mask group 1: After etching the single crystal substrate, the second mask film is removed, and etching is continued using the remaining first mask film as a mask. A method for manufacturing a 1L dielectric insulation board.