JPH01100962A - Manufacture of semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To spreading an oxide film of uniform thickness on the side surface of a first polycrystalline silicon to be subjected to insulation oxidation, and increase the dielectric strength against a second polycrystalline silicon, by eliminating a second nitride film on the main surface and the side surface of a first polycrystalline silicon to be subjected to insulating oxidation and a part of a first nitride film, and forming an oxide film on the eliminated part. CONSTITUTION:A capacitance oxide film 12, a first silicon nitride film 13, and a capacitance plate 14 are formed on a semiconductor substrate 11. After a second nitride film 15 is spread, it is coated with a silica film 16, and heat- treated. Then, by nitride film etching, the second silicon nitride film 15 spread on the main surface and the side surface part of the polycrystalline silicon 14, and a part of the silicon nitride film 13 are eliminated. By thermal oxidation method, an insulating oxide film 17 is spread on the main upper surface and the side surface of a capacitance plate 14. Then, by etching, the nitride film 15 and the capacitance oxide film 12 except capacitance part are eliminated. A gate oxide film 18 and a second polycrystalline silicon film 19 are newly spread, and a gate electrode is formed by photoetching method.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor integrated circuit device, and more particularly to a method of manufacturing a transistor type dynamic memory cell.

[Conventional technology]

Conventionally, a nitride film was used as this type of capacitive insulating film.
The manufacturing method of the transistor type dynamic memory cell is the second one.
The manufacturing method shown in Figures (a) to 2(d) was followed. That is, as shown in FIG. 2(a)K, an oxide film 2 is formed on the main surface of the semiconductor substrate 21 where each charge storage region is defined.
2, a first silicon nitride film 23 is deposited on its surface, and then, as shown in FIG. 2(b), a first polycrystalline silicon film is grown and then etched using a photoetching method. A portion of the capacitor plate 24 is removed, and then, as shown in FIG. 2(c)K, the capacitor plate 2
An insulating thermal oxide film 27 is deposited on the main surface and side surfaces of 4,
The first nitrided JG at a location other than the lower part of the first polycrystalline silicon 24! 23. The oxide film 22 is removed by a wet etching method, and a gate thermal oxide film 28 is formed on the surface by a thermal etching method.
After depositing a polycrystalline silicon film 29, and then growing a second polycrystalline silicon film 29, a gate electrode is formed by photo-etching.

[Problem that the invention seeks to solve]

In the conventional manufacturing method described above, the first polycrystalline silicon film 2
4, when depositing the insulating thermal oxidation layer 27, the first silicon nitride film 23 is difficult to oxidize, so if the thermal oxidation layer 27 deposited on the side surface of the polycrystalline silicon film 24 has a --like thickness, First, when the second polycrystalline silicon film 29 is deposited, the first
The gap between the first polycrystalline silicon film 24 and the first polycrystalline silicon film 24 becomes distorted and the insulating thermal oxide film 27 does not serve a sufficient purpose of insulation, and in the worst case, the first polycrystalline silicon film 24 and There was a drawback that the polycrystalline silicon 29 of No. 2 would be short-circuited.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor integrated circuit device that solves the above-mentioned drawbacks, prevents the insulating film under the gate electrode from becoming locally thin, and prevents dielectric breakdown and short circuit accidents. It is in.

[Means for solving problems]

The structure of the present invention is a method of manufacturing a semiconductor integrated circuit device for forming a transistor-type dynamic memory cell using a nitride film as a capacitive insulating film, in which at least a first nitride film is formed on the main surface of a semiconductor substrate. Then, a first polycrystalline silicon film is formed, and this film is etched using a photoetching method to form a cell plate, and then a second nitride film is grown on the surface, a silica film is applied, and heat treatment is performed. After etching, the second nitride film on the first polycrystalline silicon film is partially etched, and this nitride film is etched to remove the main surface and side surfaces of the first polycrystalline silicon film. a step of removing a portion of the second nitride film and the first nitride film that are in contact with the silica film; further forming an oxide film on the main surface and side surfaces; The nitride film is removed and a gate electrode made of a polycrystalline silicon film is formed.

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

FIGS. 1(a) to 1(h) are cross-sectional views showing a method of manufacturing a semiconductor integrated circuit device according to an embodiment of the present invention in the order of steps. First, in FIG. 1(a), a capacitive oxide film 1 is formed on the main surface of the semiconductor substrate 11 where charge storage regions are respectively defined.
A first silicon nitride film 13 is deposited on the oxide film 12. Next, as shown in FIG. 1(b), the first
A first polycrystalline silicon is deposited on the silicon nitride film 13, and a cell plate 14 is formed by photoetching. Next, in FIG. 1(c), after a second nitride film 15 was deposited on the negative side, a silica film 16 was applied as shown in FIG. 1(d), and heat treatment was performed for a period of time.

Next, in FIG. 1(e), the silica film 16 was partially etched so that the portion 105 attached to the main surface of the polycrystalline silicon 14 was exposed. In FIG. 1(f), the second silicon nitride film 15 and a part of the first silicon nitride film 13 adhering to the main surface and side surfaces of the polycrystalline silicon 14 are removed by nitride film etching. do. In FIG. 1 ω, insulating oxide yX17 with a -like thickness and good shape is deposited on the upper and side surfaces of the main surface of the capacitor plate 14 by thermal oxidation. Next, in FIG. 1(h), the nitride film 15 and the capacitive oxide film 12 in the portion other than the capacitive part are removed by etching, and a new gate oxide film 18 is deposited by a thermal oxidation method. Polycrystalline silicon film 19
A gate electrode is formed by depositing and photo-etching.

〔Effect of the invention〕

As explained above, the present invention removes the second nitride film on the main surface and side surfaces of the first polycrystalline silicon to be insulated and oxidized, and a part of the first nitride film. However, by forming an oxide film thereon, it is possible to break the oxide film with a similar thickness to the side surface of the first polycrystalline silicon, thereby obtaining sufficient dielectric strength with respect to the second polycrystalline silicon. It has the effect of being able to

[Brief explanation of the drawing]

FIGS. 1(a) to 1(h) are cross-sectional views showing the manufacturing method of a semiconductor integrated circuit device according to an embodiment of the present invention in the order of steps, and FIGS. 2(a) to 2(d) are sectional views of the conventional FIG. 11.21... Semiconductor substrate, 12.22...
...Thermal oxide film, 13,23...First silicon nitride film, 105...Second silicon nitride film,
14.24...Polycrystalline silicon film (capacitance plate), 16...Silica film, 17,27.
...Insulating thermal oxide film, 18,28...Gate thermal oxide film, 19.29...Polycrystalline silicon film (gate). Agent Patent Attorney Uchihara Oto 1 Figure 7 Figure 2

Claims (1)

[Claims] In a method for manufacturing a semiconductor integrated circuit device in which a one-transistor type dynamic memory cell is formed using a nitride film as part of a capacitor insulator, an oxide film is coated on the main surface of a semiconductor substrate in which charge storage regions are respectively defined. a step of depositing a first nitride film on the oxide film, growing a first polycrystalline silicon film on the first nitride film, and forming a counter electrode of the charge storage region by photo-etching. Next, a second nitride film is deposited on the surface, a silica film is applied, a heat treatment is performed, and then an etch back is performed to form a second cell plate on the first polycrystalline silicon film. a step of exposing the nitride film, a step of etching and removing the second nitride film deposited on the main surface and side surfaces of the first polycrystalline silicon film, and a step of etching and removing the first nitride film exposed by the etching. a step of etching and removing the silica film; a step of depositing an oxide film on the main surface and side surfaces of the first polycrystalline silicon by a thermal oxidation method; 1. A method for manufacturing a semiconductor integrated circuit device, comprising the step of removing a nitride film by etching.