JP2569365B2 - Method for manufacturing semiconductor integrated circuit device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor integrated circuit device, and more particularly to a method of manufacturing a one-transistor dynamic memory cell. The memory cell includes one transistor for switching between writing and reading, and one capacitor for storing and storing electric charge. Since the number of elements per bit is small, it has been widely used as an inexpensive large-capacity storage device.

3 (a) to 3 (d) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining an example of a conventional manufacturing method. First, as shown in FIG. 3A, an oxide film 2 and a nitride film 3 are formed on a semiconductor substrate 1 in this order. Next, as shown in FIG. 3 (b), a polycrystalline silicon layer is formed, and unnecessary portions are removed by a photoetching method to form a capacitor electrode 4.

Next, as shown in FIG. 3 (c), in order to insulate the capacitor electrode 4, the capacitor electrode 4 made of polycrystalline silicon is thermally oxidized. As a result, the region of the nitride film 3 where the transfer gate is to be formed is hardly oxidized, and is not oxidized by the nitride film 3 in contact with the polycrystalline silicon layer. Formed.

Next, as shown in FIG. 3 (d), unnecessary portions of the nitride film 3 and the oxide film 2 are removed by a wet etching method and thermally oxidized to form an oxide film to be the gate insulating film 6. Next, a polycrystalline silicon layer is grown on the insulating film 5 and the gate insulating film 6, and phosphorus is diffused in the polycrystalline silicon layer so as to have conductivity. Next, unnecessary portions of the polycrystalline silicon layer are removed by etching to form word lines 7.

The transistor is manufactured by a known manufacturing technique in which a source region and a drain region are formed so as to straddle a gate insulating film adjacent to the capacitor electrode 4.

[Problems to be solved by the invention]

However, in the above-described conventional manufacturing method, as shown in FIG. 3 (b), since the nitride film 3 is used as the dielectric for determining the capacitance of the capacitor, only the oxide film is used instead of the nitride film. Although the capacitance of the capacitor can be increased several times as compared with the case where it is formed, since the nitride film is hardly oxidized, the distance between the insulating films 5 and 6 between the capacitance electrode 4 and the word line 7 is low. A uniform film thickness is not formed, and the shape becomes locally thin and enters the warp. Moreover, since the word line etching residue 8 is formed,
There is a problem that the insulation of the insulating film 5 is broken, and the etching residue 8 of the word line and the capacitor electrode 4 are short-circuited.

An object of the present invention is to provide a method of manufacturing a semiconductor integrated circuit device which solves such a problem.

[Means for solving the problem]

A method of manufacturing a semiconductor integrated circuit device according to the present invention includes the steps of: forming a capacitive insulating film on a semiconductor substrate; growing a polycrystalline silicon layer on the capacitive insulating film; and insulating the polycrystalline silicon layer by thermal oxidation. Forming a film, removing the unnecessary insulating film and the polycrystalline silicon layer by a photo-etching method to form a capacitor electrode, and forming a thermal oxide film on the side surface of the capacitor electrode and further growing by a CVD method. And forming an oxide film.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

1 (a) to 1 (g) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining a first embodiment of the manufacturing method of the present invention. First, as shown in FIG. 1A, an oxide film 2 and a nitride film 3 are formed on a semiconductor substrate 1 as in the conventional example.

Next, as shown in FIG. 1B, a polycrystalline silicon layer is grown on the nitride film 3 to form a capacitor electrode 4a. next,
Phosphoric acid is diffused into the capacitor electrode 4a made of polycrystalline silicon to have conductivity. Next, an insulating film 5a is formed on the capacitor electrode 4a by a thermal oxidation method. Next, as shown in FIG. 1 (c), the unnecessary oxide film 2, nitride film 3, capacitor electrode 4a and insulating film 5a are removed by photoetching, and the oxide film 2a, nitride film 3a, capacitor electrode 4b and insulating film 5a are removed. The film 5b is formed.

Next, as shown in FIG. 1D, the polycrystalline silicon layer on the side surface of the capacitor electrode 4b is oxidized to turn the insulating film 5b into an insulating film 5c. At the same time, an oxide film 10 is formed on the semiconductor substrate 1. Next, as shown in FIG.
An oxide film 8 is grown. After that, CV
The D oxide film 8 is hardened. Next, as shown in FIG. 1 (f), the CVD oxide film and the insulating film 5c are selectively etched to expose the semiconductor substrate 1 and form the insulating film 9.

Next, as shown in FIG. 1 (g), a gate oxide film 6a is formed by thermal oxidation, and a polycrystalline silicon layer is grown on the insulating oxide film 9 and the gate oxide film 6a. The word line 7a is formed by conducting diffusion by phosphorus diffusion and selective etching by a photo-etching method.

By manufacturing in this manner, there is an advantage that the insulating film does not have a locally thin and irregular shape and does not short-circuit with the word line remaining after etching.

2 (a) to 2 (g) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining a second embodiment of the manufacturing method of the present invention. This memory cell is an example in which a manufacturing method is performed when a capacitance is formed in a groove. First, the second
As shown in FIG. 1A, a field oxide film 12 is formed on a semiconductor substrate 1 by a known method.
An oxide film 2b and a nitride film 3b are sequentially formed on the surfaces of the field oxide film 13 and the field oxide film 12.

Next, as shown in FIG. 2B, a polycrystalline silicon layer is grown on the nitride film 3b. Phosphorus is diffused to form the capacitor electrode 4c with conductivity. Next, as shown in FIG. 2C, an insulating film 5d of an oxide film is formed on the capacitor electrode 4c by thermal oxidation. Further, polycrystalline silicon is grown in the groove, and phosphorus is diffused into the polycrystalline silicon to form a polycrystalline silicon layer 11 with conductivity.

Next, as shown in FIG. 2D, unnecessary insulating films 5d,
Remove part of the capacitor electrode 4c, the oxide film 2b and the nitride film 3b,
The oxide film 2c, the nitride film 3c, and the capacitor electrode 4d are used. Further, the polycrystalline silicon layer on the side surface of the capacitor electrode 4d is oxidized by thermal oxidation to form an insulating film 5e and an oxide film 10a. Next, as shown in FIG. 2 (e), an oxide film is grown on the insulating film 10a and the insulating film 5e by a CVD method and formed on the insulating film 5f. afterwards,
The insulating film 5f, which is an oxide film, is hardened by heat treatment.

Next, unnecessary portions of the insulating film 5f and the oxide film 10a are removed by etching so that the semiconductor substrate 1 and the field oxide film 12 near the capacitor electrode 4d are exposed, thereby forming an insulating film 5g. Next, as shown in FIG. 2 (g), after forming a gate oxide film 6b by thermal oxidation, a polycrystalline silicon layer is grown,
After phosphorus expansion, the word line 7b is formed by selective etching and removal.

〔The invention's effect〕

As described above, according to the present invention, by forming an insulating film surrounding a capacitor electrode by a combination of a thermal oxide film and an insulating film formed by a CVD method, the thickness of the insulating film becomes uniform,
There is an effect that a method of manufacturing a semiconductor integrated circuit device in which the insulating film is not broken down and the word line and the capacitor electrode are not short-circuited is obtained.

[Brief description of the drawings]

1 (a) to 1 (g) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining a first embodiment of the manufacturing method of the present invention, and FIGS. 2 (a) to 2 (g) show the present invention. Sectional views of a semiconductor chip shown in the order of steps for explaining the embodiment of FIG. 2 of the manufacturing method shown in FIG. 2. FIGS. 3 (a) to (d) are shown in the order of steps for explaining an example of the conventional manufacturing method. FIG. 4 is a cross-sectional view of a semiconductor chip that has been damaged. 1 .... Semiconductor substrate, 2, 2a, 2b, 2c ... Oxide film, 3,3
a, 3b, 3c: nitride film, 4, 4a, 4b, 4c, 4d: capacitance electrode, 5, 5a, 5b, 5c, 5d, 5e, 5f, 5g: insulating film, 6,
6a, 6b: gate oxide film, 7, 7a, 7b: word line, 8
... CVD oxide film, 9 insulating film, 11 polycrystalline silicon layer, 12 field oxide film.

Claims (1)

(57) [Claims] A step of forming a capacitance insulating film including a nitride film on a semiconductor substrate; a step of forming a polycrystalline silicon layer on the capacitance insulating film; and a thermal oxidation on the polycrystalline silicon layer by thermal oxidation. Forming a capacitor electrode by selectively removing the insulating film, the polycrystalline silicon layer, and the insulating film by a photoetching method, and exposing the semiconductor substrate; and forming a side surface of the capacitor electrode. And a step of oxidizing the exposed semiconductor substrate, a step of forming an oxide film on the entire surface by a CVD method, and a step of selectively removing the oxide film on the semiconductor substrate by a photoetching method to expose the semiconductor substrate. And a step of forming a gate insulating film on the semiconductor substrate by a thermal oxidation method.