JPH11265978A - Manufacture of semiconductor device and semiconductor device using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the capacitance of a capacitor without changing the occupying area of the capacitor on a semiconductor substrate. SOLUTION: A polycrystal silicon film 2 formed on a semiconductor substrate 1 is etched into a head-mounting shaped conical form with a circular resist pattern 3 as a mask, and a lower electrode 2a is formed. A silicon oxide film 4 and a polycrystal silicon film 5 are formed so as to cover the lower electrode 2a, and a capacitor 10 is formed. At this time, e.g. the polycrystal silicon film 2 of the capacitor 10 is formed thicker. Etching is performed by using the above described resist pattern 3, and so on. When the tilt angle is made large with the bottom area of the lower electrode 22 being intact by this way, the area of the slant surface of the lower electrode 2a is increased accompanied by the change in slant angle. That is to say, the surface area of the silicon oxide film 4 becomes also large. Since the bottom area is same, the capacitance of the capacitor 10 is increased with the occupying area of the lower electrode 2a on the semiconductor substrate 1 being same.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device and a semiconductor device using the same, and more particularly, to a capacitor capable of obtaining a larger capacitance without changing the area occupied on a substrate.

[0002]

2. Description of the Related Art Conventionally, when a capacitor is formed on a semiconductor substrate, for example, as shown in FIG. 4, a polycrystalline silicon film 11 is formed on a semiconductor substrate 1 and a silicon oxide film 12 is formed thereon. After that, the polycrystalline silicon film 13 is formed again, and this is formed by etching or the like.

[0003]

However, in the above-mentioned conventional semiconductor device, as shown in FIG. 4, the capacitor has a rectangular parallelepiped shape, and the capacitance of the capacitor is increased without changing the thickness of the silicon oxide film 12. In this case, since the capacitance of the capacitor is determined by the plane area of the silicon oxide film 12, the area occupied by the capacitor on the semiconductor substrate 1 increases, which hinders miniaturization and high integration of the semiconductor device. . Therefore, a semiconductor device capable of increasing the capacitance of a capacitor without increasing the occupied area and a method for manufacturing the same have been desired.

Therefore, the present invention has been made in view of the above-mentioned conventional unsolved problem, and it is possible to increase the capacitance of a capacitor without changing the area occupied by the capacitor on a semiconductor substrate. It is an object to provide a semiconductor device and a method for manufacturing the same.

[0005]

In order to achieve the above object, a method of manufacturing a semiconductor device according to claim 1 of the present invention comprises:
A method for manufacturing a semiconductor device in which a capacitor is formed on a substrate, comprising: forming a film for forming an electrode on the substrate;
This is etched to form a truncated cone-shaped electrode nucleus, an insulating film is formed so as to cover the entire surface of the electrode nucleus, and further, an electrode film is formed so as to cover the entire surface of the insulating film. It is characterized by forming a film.

According to the first aspect of the present invention, after a film for forming an electrode is formed on a substrate, it is etched into a truncated cone shape, that is, the upper portion of the cone shape is cut along a plane parallel to the bottom surface. Then, the upper surface is removed and the upper surface is etched into a flat shape, thereby forming a truncated cone-shaped electrode core. Then, an insulating film is formed so as to cover the entire surface of the electrode nucleus, and further, the entire surface of a truncated cone having a laminated structure of the electrode nucleus and the insulating film, ie, the upper surface and the inclined surface of the insulating film The electrode film is formed so as to cover the substrate, thereby forming a truncated cone-shaped capacitor.

To change the capacitance of this capacitor,
The plane area of the insulating film may be changed, that is, when forming a film for forming an electrode to be a core for an electrode later, the film thickness may be adjusted or the film for forming an electrode may be formed into a truncated shape. By adjusting the shape of the resist at the time of etching into a cone shape, the inclination of the inclined surface of the electrode core having a truncated cone shape may be changed, and the plane area of the inclined surface may be changed. At this time, since the bottom area, that is, the occupied area of the capacitor on the substrate is the same, the capacitance of the capacitor is changed with the occupied area being the same.

According to a second aspect of the present invention, there is provided a semiconductor device having a capacitor formed on a substrate, wherein the capacitor is formed in a truncated cone shape, and the center of the cone shape is formed. An electrode nucleus formed in contact with the substrate in the portion, an electrode film formed on the outer periphery of the cone,
It is characterized by having a laminated structure of an insulating film formed between the electrode nucleus and the electrode film and separating the electrode nucleus and the electrode film.

According to the second aspect of the present invention, a truncated cone-shaped capacitor is formed on a substrate.
An electrode nucleus is formed in contact with the substrate at the center of the cone on the frustum, an electrode film is formed on the outer periphery of the cone, and these are separated between the electrode nucleus and the electrode film. Thus, an insulating film is formed.

Here, in order to change the capacitance of the capacitor, the plane area of the insulating film may be changed. In this case, the area of the inclined surface of the insulating film formed in the shape of a truncated cone is changed. It should be done. For this purpose, the inclination of the inclined surface may be changed, so that the capacitance can be changed while keeping the bottom area, that is, the area occupied by the capacitor on the substrate.

[0011]

Embodiments of the present invention will be described below with reference to embodiments. First, as shown in FIG. 1A, a polycrystalline silicon film 2 having a film thickness L is formed on a silicon substrate 1, a resist is applied on the polycrystalline silicon film 2, and a diameter for forming a lower electrode is formed. An R circular resist pattern 3 is formed.

Next, as shown in FIG. 1B, using the resist pattern 3 as a mask, the polycrystalline silicon film 2 is taper-etched, and as the distance from the position corresponding to the end of the resist pattern 3 increases, Etching is performed so that the film thickness becomes thin, and the diameter of the upper surface is R, the diameter of the bottom surface is L, the height is H, and the inclination angle of the inclined surface is θ. Lower electrode (core for electrode) 2a
To form This taper etching is performed, for example, by using SF ₆
/ C ₂ HCl ₂ F ₃ mixed gas of 10-19 / 51-
This is performed under the conditions of 60 [SCCM] flow, 10 [mTorr], and RF power of 180 [W].

Next, the resist pattern 3 is removed, and FIG.
As shown in (c), a silicon oxide film (insulating film) 4 is formed on the entire surface of the lower electrode 2a, that is, on the entire upper plane and the inclined surface. This silicon oxide film 4 is, for example,
Oxidation is performed in a dry O ₂ atmosphere at 1050 ° C. for 15 seconds to form a film of 250 ° C.

Further, a polycrystalline silicon film (electrode film) 5 as an upper electrode is formed on the entire surface of the silicon oxide film 4, that is, on the upper flat surface and the entire inclined surface. This polycrystalline silicon film 5 is formed by, for example, a decompression CV of monosilane.
According to Method D, under conditions of 640 ° C. and 15 Pa,
500 [５００] is formed.

Thus, as shown in FIG. 1C, a laminated structure of the lower electrode 2a made of polycrystalline silicon, the silicon oxide film 4, and the polycrystalline silicon film 5 as the upper electrode is formed. A truncated conical capacitor 10 is formed.

Here, the capacitor 10 shown in FIG.
In the case where the capacitance is increased, when forming the polycrystalline silicon film 2 to be the lower electrode 2a later (FIG. 1A), the film thickness H 'is increased (H'> H). ),
Tapered etching is performed so that the diameter R of the circular resist pattern 3 is the same, and the bottom area of the frustoconical shape serving as the lower electrode 2a is constant, that is, the diameter of the bottom surface is L. Do.

Then, in the same manner as above, a silicon oxide film 4 and a polycrystalline silicon film 5 are formed. This allows
As shown in FIG. 2, a truncated cone-shaped capacitor 10 'is formed in the same manner as described above.
a ′ has the same top surface diameter R and bottom surface diameter L as compared to the lower electrode 2a shown in FIG.
Is higher (H ′> H), and the inclination angle θ ′ of the inclined surface is larger (θ ′> θ), resulting in a truncated cone. Therefore, the surface area of the silicon oxide film 4 'formed on the surface of the lower electrode 2a' is smaller than that of the silicon oxide film 4 shown in FIG.
The diameter R of the bottom surface of the lower electrode 2a 'is formed to be the same, so that the silicon oxide film 4' and the silicon oxide film 4 'laminated on the lower electrode 2a' This means that the capacitor 10 'having a larger capacitance has been formed with the same occupied area on the semiconductor substrate 1 after the formation of the crystalline silicon film 5'.

Therefore, when the lower electrode 2a is formed, by adjusting its shape, the occupied area on the semiconductor substrate 1 is constant, but the capacitors 10 having different capacities can be formed. Miniaturization,
The capacity can be increased without hindering high integration.

In the above embodiment, when forming the polycrystalline silicon film 2 to be the lower electrode 2a later,
Although the case where the capacitance is increased by adjusting the film thickness has been described, for example, the diameter of the circular resist pattern 3 is adjusted to change the inclination angle θ of the inclined surface of the lower electrode 2a. In this case,
The capacitance can be increased without changing the height of the capacitor 10.

In the above embodiment, the case where the circular resist pattern 3 is formed and the tapered etching is performed to form the frustum-shaped conical lower electrode 2a has been described. For example, as shown in FIG. 3, by forming a rectangular resist pattern 3 and performing taper etching, a truncated quadrangular pyramid-shaped lower electrode 2a may be formed. Since the surface area of the silicon oxide film 4 can be changed by changing the inclination angle of the truncated quadrangular pyramid-shaped inclined surface, the same operation and effect as described above can be obtained. Further, the present invention is not limited to the truncated quadrangular pyramid, but may be formed by forming a polygonal resist pattern 3 to form a truncated polygonal pyramid. Can be obtained.

In the above-described embodiment, the case where a capacitor having a three-layer structure of a polycrystalline silicon film, a silicon oxide film, and a polycrystalline silicon film is described. However, the present invention is not limited to this. The present invention can be applied to a case where a capacitor having a three-layer structure of a film and a metal is formed.

[0022]

As described above, according to the first aspect of the present invention,
According to the method for manufacturing a semiconductor device according to the above, after forming a film for forming an electrode, the film is etched into a truncated cone shape to form a core for the electrode, and covers the entire surface of the core for the electrode. Since the electrode film is formed so as to cover the entire surface of the insulating film, when forming the electrode nucleus, the truncated cone-shaped cone is formed with the bottom area as it is. By adjusting the angle of inclination of the inclined surface, the surface area of the insulating film formed on the electrode core can be changed,
The capacitance of the capacitor can be changed while keeping the area occupied by the capacitor on the substrate constant.

Further, according to the semiconductor device of the present invention, a capacitor is formed in a truncated cone shape, and this capacitor is provided at the center of the cone shape with an electrode core and the cone shape. An electrode film was formed on the outer periphery, and between the electrode nucleus and the electrode film, a laminated structure was formed with an insulating film separating the electrode nucleus and the electrode film. The area of the insulating film can be changed by changing the inclination angle of the inclined surface while keeping the bottom area of the body shape constant, so that the capacitance can be changed while keeping the occupied area on the semiconductor substrate constant.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a part of a manufacturing process of a semiconductor device according to the present invention.

FIG. 2 is an explanatory diagram for explaining the operation of the present invention;

FIG. 3 is an explanatory diagram showing another example of the present invention.

FIG. 4 is a cross-sectional view showing a part of a manufacturing process of a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Polycrystalline silicon film 2a Lower electrode 3 Resist pattern 4 Silicon oxide film 5 Polycrystalline silicon film

Claims (2)

[Claims] 1. A method of manufacturing a semiconductor device in which a capacitor is formed on a substrate, wherein a film for forming an electrode is formed on the substrate and then etched to form a frustum-shaped cone-shaped electrode. Forming a nucleus, forming an insulating film so as to cover the entire surface of the electrode nucleus, and further forming an electrode film so as to cover the entire surface of the insulating film. . 2. A semiconductor device having a capacitor formed on a substrate, wherein the capacitor is formed in a truncated cone shape, and an electrode is formed at the center of the cone shape in contact with the substrate. Laminated structure of a core for electrode, an electrode film formed on the outer periphery of the cone, and an insulating film formed between the electrode core and the electrode film and separating the electrode core and the electrode film. A semiconductor device, characterized in that: