JPS6079737A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make surface smooth by a method wherein polycrystalline silicon films in the groove for separating elements are formed evenly and then the oxidation degree on the surface of these silicon films is adjusted. CONSTITUTION:A buried layer 22, a single crystal film 23, a silicon oxide film 24, a silicon nitride film 25 and a groove 27 are formed on a substrate 21. Then a silicon oxide film 29, a silicon nitride film 30 and polycrystalline silicon film 31 are formed on the side wall of the groove 27. Firstly a polycrystalline film 31' only is left on the side wall of the groove 27. Secondly the film 31' is formed into a P type polycrystalline silicon film 33 with high concentration. Thirdly a polycrystalline silicon film 32 is deposited to form it into a P type polycrystalline silicon film 34 with high concentration. Fourthly the film 32 is removed to make it lower than the surface of the groove 27 by means of etching the film 34. Fifthly the film 34 is oxidized to form a silicon oxide film 35. Finally another silicon oxide film 37 may be formed on the surface of said film 23 to form electrode wirings 38-40.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention relates to a method of manufacturing a semiconductor device, and in particular, a method for manufacturing a semiconductor device, in which deep grooves are formed between elements, and by filling the grooves with an insulating material, etc. The present invention relates to a method for manufacturing a semiconductor device in which the semiconductor devices are separated.

[Prior art]

Recently, with the progress of miniaturization of devices, it has become necessary to remove bird's beaks that occur when insulating layers are separated by selective oxidation in order to further increase the density and integration of LSIs.
'', various methods have been proposed to improve this. One of the most representative methods is the groove filling quick separation method.

FIGS. 18) to 18(d) are cross-sectional views shown in the order of steps for explaining a method of manufacturing a semiconductor device using the conventional trench filling color separation method.

First, as shown in FIG. 1(a), a groove is formed using a well-known method in a substrate consisting of a p-region medium conductor substrate l, a heavily doped n-type buried layer 2, and a single crystal film 3 formed by an epitaxial method. 4, and then a silicon oxide film 5 and a silicon nitride film 6 were completely formed on the surface of the groove 4, and then.

Seven polycrystalline silicon films are deposited on the surface of this silicon nitride film 6 and buried in m4*.

Next, as shown in FIG. 1(b), the surface of the polycrystalline silicon film in the upper region of the groove 4 is covered with a photoresist film 8, and unnecessary portions of the polycrystalline silicon film are removed.

However, in this removal process, it is difficult to remove only the polycrystalline silicon film other than the groove by etching, and the polycrystalline silicon in the groove area is over-etched, as shown in FIG. 1(e).
If the position of the photoresist 8 is not accurate, a large step 9 will occur in the groove region as shown in FIG.

When such a step is formed, the metal wiring is likely to be disconnected, and there is a drawback that it is impossible to manufacture an FC semiconductor device despite the progress of high density and high integration of FC semiconductors.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks, to provide a method for manufacturing a semiconductor device in which the surface of a groove for isolation between elements is substantially flattened, and is suitable for high density and high integration.

[Structure of the invention]

From the surface of the opposite conductivity type single crystal film to a semiconductor substrate composed of a semiconductor substrate of one conductivity type and a reverse conductivity type single crystal film,
a step of forming a groove that reaches the conductivity type substrate; a step of forming a silicon oxide film on the side and bottom surfaces of the groove;
Depositing a first polycrystalline silicon film to which no impurities are added on the surface of the silicon oxide film, and removing gold from the polycrystalline silicon film other than the side surfaces of the groove by anisotropic etching the first polycrystalline silicon film. and a step of making the first polycrystalline silicon film remaining on the side surface of the groove into a high concentration-conductivity type.

A step of fully depositing a second polycrystalline silicon film to which no impurities are added on the surface of the high-concentration conductive polycrystalline silicon film and the surface pressure of the oxidation-resistant film, and burying a trench, and a second polycrystalline silicon film inside the trench. A step of making the film a high concentration-conductivity type, and a step of making the film a high concentration conductivity type, and
a step of selectively removing only the polycrystalline silicon film, and a step of removing the surface region of the highly-conductive polycrystalline silicon film and leaving the surface of the highly-conductive polycrystalline silicon film inside the groove. and converting the surface area of the high-concentration conductive FILFM polycrystalline silicon film into an all-silicon oxide film, and substantially flattening the surface of the silicon oxide film and areas other than the grooves. .

[Explanation of Examples]

The following is a drawing regarding an embodiment of the present invention. Refer to and explain.

FIGS. 18) to 18h are cross-sectional views shown in order of steps for explaining an embodiment of the present invention.

First, as shown in FIG. 2 (18), a silicon oxide film 24 and a nitride silicon semiconductor substrate are covered with a silicon semiconductor substrate 21, a high-concentration Na buried layer 22, and an n-type single crystal film 23i formed by an epitaxial method. A silicon film 25' (is formed, and then a trench 27t- reaching the p-view silicon semiconductor substrate 21 is formed using the photoresist film 26 as an etching resistant material.
Form.

The grooves 27 are formed using, for example, a mixed plasma of carbon tetrachloride and oxygen. Next, as shown in FIG. 2(b), a p-type region 28t for preventing the formation of an inversion channel is formed at the bottom of f127 by ion implantation.
After removal, a silicon oxide film 29 and a nitride film 30t are formed on the side walls of the groove 27. Next, an impurity-free first film having a thickness of 0.1 to 1.0 μm is deposited on the surface of the silicon nitride film 30.
Polycrystalline silicon film 31'fr: is deposited so that the groove 27 is not completely buried.

Next, as shown in FIG. 2C, using a reactive ion etching (IE) method, the polycrystalline silicon film 31 in the area other than the groove, that is, the flat area, and the polycrystalline silicon film 31 at the bottom of the groove 27 are etched. The entire film is removed, leaving only the undoped polycrystalline silicon film 31' on the trench sidewalls. Next, boron diffusion or boron ion implantation is performed to form the polycrystalline silicon film 31'' left on the side wall of the trench to a high concentration p! polycrystalline silicon film 33.Next, FIG. 2(d) As shown in
A polycrystalline silicon film 32t of 0.5 to 3 μm thick is deposited,
Completely bury it in the groove 27. Continued from 900 to 120
A heat treatment is performed at 0° C. to completely diffuse boron from the high concentration PA polycrystalline silicon 33 into the second polycrystalline silicon film 32, and convert the polycrystalline silicon film 32 in the groove region into a high concentration p-type polycrystalline silicon film 34.
Make it.

Next, as shown in Figure 2(e), using a mixture of potassium hydroxide or hydrazine and isopropanol,
Only the polycrystalline silicon film 32 is completely etched away. As is known, the above-mentioned mixed solution has an extremely low etching rate in the high-concentration p-type region, so the high-concentration polycrystalline silicon film 3
4 remains almost unetched.

'Next, as shown in FIG. 2(f), the high concentration p I! ! ! Polycrystalline silicon film 34? Etching is performed using a mixed solution of l-hydrofluoric acid, nitric acid, acetic acid, etc., so that the surface of the high concentration PI polycrystalline silicon film 34 is 0.0% lower than the groove surface.
The height should be 5 to 0.5 μm lower.

Next, as shown in FIG. 2(g), a silicon nitride film 30t
-High concentration p-type polycrystalline silicon film 3 as an oxidation-resistant mask
4t-selective oxidation is performed to form a silicon oxide film 35, and the surface of this silicon oxide film 350 is made substantially flat with the surface of the silicon nitride film 30.

Finally, as shown in FIG. 2(h), the entire silicon oxide film 37 is again formed on the surface of the ZJn type single crystal film 230 formed by the epitaxial method, and the base, emitter, etc. regions are completely covered by a well-known method. By forming the electrode wirings 3B, 39, 40, etc., a semiconductor device having a flat surface and separated by the inter-element t-e can be obtained.

As explained above, in this embodiment, the polycrystalline silicon film #1 in the groove is formed in a self-aligned manner so that it is flat and slightly lower than the groove surface, and then the surface of the polycrystalline silicon film is selectively oxidized. By adjusting the degree of oxidation, it is easy to make the surface almost flat with the silicon nitride film. With the smooth surface thus obtained, there will be no problem of cutting the metal wiring formed later at the stepped portion, and since the surface is smooth, it is effective for high density and high integration.

〔Effect of the invention〕

As described above, according to the present invention, since the groove region is substantially flat, there is no disconnection in the metal wiring extending above the groove, and a highly reliable semiconductor device can be obtained.

Moreover, as a result, it is highly effective for higher density and higher integration.

[Brief explanation of drawings]

1(a) to 1(d) are comparative cross-sectional views showing the process order for explaining a method of manufacturing a semiconductor device using the conventional trench-buried isolation method, and FIG. FIG. 3 is a cross-sectional view showing the order of steps for explaining one embodiment. l...p-type semiconductor substrate, 2...n-type buried layer, 3...single crystal film, 4...groove%5
...Silicon oxide film, 6...Silicon nitride film, 7...Polycrystalline silicon film, 8...Photoresist film, 9.10...・Step, 21...
. . . p-type semiconductor substrate, 22 . . . n-type buried layer,
23... N-type epitaxial layer, 24...
...Silicon oxide film, 25...Silicon nitride film, 2
6...Photoresist film. 27...Groove, 29...Silicon oxide film,
30...Silicon nitride film, 31.32...
・Polycrystalline silicon film. 33.34...pH! Polycrystalline silicon film, 35.
...Silicon oxide film, 37...Silicon oxide film, 38,39°40.41...Electrode arrangement #i!
.・−１−、Representative Patent Attorney Susumu Uchihara 1 ゛) Raku 1 time 2 times

Claims (1)

[Claims] A step of forming a layer 1 on a semiconductor substrate composed of a conductive type semiconductor substrate and a transparent conductive type single crystal film from the surface of the opposite conductive type single crystal film to the - conductive type semiconductor substrate; a step of forming a silicon oxide film on the side and bottom surfaces of the groove, a step of forming an oxidation-resistant film on the surface of the silicon oxide film, and a step of forming a first polycrystalline silicon film to which no impurities are added on the surface of the oxidation-resistant film. a step of depositing the first polycrystalline silicon film, a step of removing the polycrystalline silicon film other than the side surfaces of the groove by anisotropic etching the first polycrystalline silicon film, and a step of removing the first polycrystalline silicon film remaining on the side surfaces of the groove. a step of forming a high concentration conductive type polycrystalline silicon film; a step of depositing and burying a second polycrystalline silicon film to which no impurities are added on the surface of the core high concentration conductive type polycrystalline silicon film and the surface of the oxidation-resistant film; , a step of making the second polycrystalline silicon film inside the groove a high concentration-conductivity type;
0 Polycrystalline silicon film only? a step of selectively removing the polycrystalline silicon film; a step of removing the surface region of the high concentration conductivity type polycrystalline silicon film and leaving the surface of the high concentration conductivity type polycrystalline silicon film inside the groove; 1. A method for manufacturing a semiconductor device, comprising: converting the entire surface area of a conductive polycrystalline silicon film into a silicon oxide film, and substantially flattening the surface of the silicon oxide film and regions other than the grooves; and containing gold.