JPH11121711A - Manufacture of capacitor, manufacture of semiconductor device capacitor and semiconductor device capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a capacitor in a specific capacity by a method wherein the first metallic films having ruthenium is exposed to oxygen plasma to form a dielectric on the first metallic films further to form the second metallic film having ruthenium on the dielectric. SOLUTION: A titanium film is formed on a silicon oxide film 2 so as to form the first metallic films 5a having a metal containing ruthenium. The first metallic films 5a are treated by oxygen plasma. Next, after depositing a high dielectric film 7, the second metallic film 8 is formed. In such a constitution, the irregularities are formed on the surface of the first metallic films 5a due to the growth by the rearrangement caused by the exposition of the first metallic films 5a to the oxygen plasma. Accordingly, the surface area of the first metallic films 5a and the second metallic film 8 opposing to the former films 5a is increased. Thus, even if the height h of the first metallic films 5a is lowered the surface area similar to the conventional one can be secured, thereby enabling the capacitor in a specific capacity to be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a capacitor, a method for manufacturing a capacitor for a semiconductor device, and a capacitor for a semiconductor device.

[0002]

2. Description of the Related Art A capacitor used in a semiconductor device is formed, for example, by using ruthenium as an electrode and providing a high dielectric substance between the electrodes, using polysilicon as an electrode, and forming a silicon oxide film and a silicon nitride between the electrodes. There is a structure provided with a film. When ruthenium is used as an electrode and a high dielectric is provided between the electrodes to form a capacitor,
Since a high-dielectric material is used, a desired capacitance of the capacitor can be obtained even if the surface area of ruthenium serving as an electrode is reduced.
It is desirable to form a capacitor by using ruthenium as an electrode and providing a high dielectric substance between the electrodes.

FIG. 3 is a view for explaining the structure of a capacitor of a conventional semiconductor device. In the figure, 1 is a substrate such as Si, 2 is a silicon oxide film, 3 is a silicon oxide film 2
, 4 is a conductive member embedded in the hole 3, 5 is a first metal film, 7 is a high dielectric film, and 8 is a second metal film.

The first metal film 5 and the second metal film 8 are made of, for example, ruthenium (element symbol: Ru). High dielectric film 7
Uses, for example, a multi-component oxide film having a high dielectric substance. In this example, a strontium barium titanate film (hereinafter referred to as BST) is used.
This will be described by way of example using a film. Conductive member 4
Is embedded in the hole 3 and the conductive member 4 is electrically connected to the substrate 1 and the first metal film 5.
And the first metal film are electrically connected.

Next, a method of manufacturing the capacitor of the conventional semiconductor device shown in FIG. 3 will be described. First, a silicon oxide film 2 is formed on a substrate 1 by a CVD method or a thermal oxidation method. Next, a mask is formed on the silicon oxide film 2 by a photolithography technique. The hole 3 is formed in the portion, and the substrate 1 is exposed from the portion where the hole 3 is formed.

Next, a conductive member 4 is buried in the hole 3 and the substrate 1 and the conductive member 4 are electrically connected. Next, after depositing a metal film having ruthenium such as a sputtering method so as to be electrically connected to the conductive member 4, a predetermined metal film is removed by a dry etching method or the like to form a first metal film. Next, after depositing the high dielectric film 7 by a CVD method or the like, a second metal film is formed by a sputtering method or a CVD method. Through the steps described above, the capacitor of the semiconductor device is formed.

When a capacitor is formed by using the above-described BST film for the high dielectric film 7 and ruthenium as the material of the electrode, the dielectric constant is higher than when a silicon oxide film and a silicon nitride film are used as a dielectric film. However, when a BST film is used, a capacitor becomes extremely high. Therefore, when a capacitor is formed using a metal containing ruthenium as an electrode material and a BST film as a dielectric film, a desired capacitance can be obtained even if the surface area is reduced to some extent. Can be obtained. Therefore, when a semiconductor device such as a dynamic random access memory (DRAM) is formed using this capacitor, the device can be made thinner and finer.

[0008]

As the degree of integration of a semiconductor device increases, miniaturization of elements for higher integration is progressing. As the degree of integration increases, the area provided for forming a capacitor has become extremely small. When miniaturizing a capacitance element such as a capacitor, it is necessary to reduce the height of an electrode serving as a constituent element as much as possible and to reduce the thickness of the capacitor as much as possible. By reducing the thickness of the capacitor, it is possible to reduce inconvenience caused by a step due to the thickness of the capacitor when forming a film formed above the capacitor. The capacitance of a capacitor is proportional to the surface area of the electrodes and inversely proportional to the distance between the electrodes. Therefore, when the degree of integration of the semiconductor device having the above structure increases, it is necessary to reduce the distance between the electrodes of the capacitor or increase the surface area of the capacitor.

In a conventional capacitor of a semiconductor device, when the surface area of the capacitor is increased, it is necessary to increase the height of the electrode (or the thickness of the capacitor). Not preferred. On the other hand, when the thickness of the BST film 7 is reduced, the withstand voltage of the BST film 7 with respect to the voltage applied to the capacitor decreases, which is not preferable.

In the conventional method for manufacturing a capacitor of a semiconductor device, since the surface of the electrode is flat, when the thickness of the BST film is made approximately the same as the conventional one, the height of the electrode is increased to obtain a desired capacitance. Could not be less than the value. The present invention has been made to solve the above problems,
A method for manufacturing a capacitor capable of obtaining a capacitor having a desired capacitance even when the thickness of the BST film is substantially the same as the conventional one and the height of the electrode is smaller than the value which has been conventionally regarded as a limit, A method for manufacturing a capacitor and a method for obtaining a capacitor of a semiconductor device manufactured by the method.

[0011]

According to the present invention, there is provided a method for manufacturing a capacitor, comprising the steps of: (a) exposing the surface of a first metal film containing ruthenium to oxygen plasma; and (b) forming a surface on the first metal film. (C) forming a second metal film having ruthenium on the dielectric;

[0012] A method of manufacturing a capacitor according to the present invention includes:
In the step of exposing the surface of the first metal film to oxygen plasma, the pressure of the oxygen plasma is set to 0.1 (Torr) to 10 (Torr).
(Torr).

[0013] The method of manufacturing a capacitor according to the present invention comprises:
In the step of exposing the surface of the first metal film to oxygen plasma, the temperature of the first metal film was adjusted from room temperature to 400 (° C.).

[0014] A method of manufacturing a capacitor according to the present invention comprises:
Ruthenium was changed to ruthenium dioxide.

The method of manufacturing a capacitor of a semiconductor device according to the present invention includes: (a) a step of forming a conductive member on a substrate; and (b) a first step of forming ruthenium on the conductive member.
(C) exposing the surface of the first metal film to oxygen plasma; (d) forming a dielectric on the first metal film; and (e) forming a dielectric on the first metal film. Forming a second metal film containing ruthenium.

In the method of manufacturing a capacitor of a semiconductor device according to the present invention, in the step of exposing the surface of the first metal film to oxygen plasma, the oxygen plasma is subjected to a pressure of 0.1 (To).
rr) to 10 (Torr).

In the method of manufacturing a capacitor of a semiconductor device according to the present invention, in the step of exposing the surface of the first metal film to oxygen plasma, the temperature of the first metal film is changed from room temperature to 400 (° C.). I made it.

In the method for manufacturing a capacitor of a semiconductor device according to the present invention, ruthenium is replaced by ruthenium dioxide.

A capacitor of a semiconductor device according to the present invention includes a substrate, a conductive member formed on the substrate, a first metal film having ruthenium or ruthenium dioxide formed on the conductive member, In a capacitor of a semiconductor device including a dielectric formed on one metal film and a second metal film having ruthenium or ruthenium dioxide formed on the dielectric, a surface of the first metal film Is characterized by being rearranged.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. FIG. 1 is a diagram for explaining a method for manufacturing a capacitor of the semiconductor device of the first embodiment. In the drawings, the same reference numerals as those in the related art are the same as or equivalent to those in the related art. In the figure, 5
a is a first metal film, and 7a is a high dielectric film. The material of the first metal film 5a is made of ruthenium. h is the height of the first metal film 5a. Asperities are formed on the surface of the first metal film 5a by the oxygen plasma treatment.
As the high dielectric film 7a, for example, a multi-component oxide film having a high dielectric is used. Here, an example using a BST film will be described.

A method for manufacturing the capacitor of the semiconductor device according to the first embodiment will be described. First, a titanium film as an adhesion layer is formed on a silicon oxide film by a sputtering method, and a first metal film 5a having a metal containing ruthenium is formed thereon by a sputtering method. The conditions for forming the first metal film 5a are as follows.

Gas pressure: 3 (mTorr) Discharge power: 400 (W) Film forming temperature: 350 (° C.) Ruthenium thick film: 200 (nm) Adhesion layer Titanium thick film: 10 (nm)

Next, the surface of the first metal film 5a is treated with oxygen plasma. The conditions of the oxygen plasma treatment are as follows.

Oxygen plasma pressure: 1 (Torr) Discharge power: 400 (W) Discharge power frequency: 13.56 (MHz) Oxygen plasma processing time: 30 (min) Temperature of sample during processing: 150 (° C.) to 200
(℃) Method of supporting sample during processing: Hold in plasma with quartz jig

The surface of the first metal film 5a made of ruthenium is roughened by the oxygen plasma treatment. The mechanism by which the surface of ruthenium is roughened by low-temperature oxygen plasma treatment is considered as follows. As an oxide of Ru,
RuO2, RuO3, RuO4 and the like. RuO2 is fairly stable to temperature and remains in a solid state,
4 is reported to be in a liquid state at about 26 ° C. and change to a gas state at about 108 ° C.

However, RuO4 is easily decomposed, and RuO4
It is easy to change to 2 etc. In the method of exposing the surface of ruthenium to oxygen plasma described in this embodiment, the surface of ruthenium is oxidized by active oxygen such as oxygen atoms generated by the plasma, and RuOx (x = 1 to 4) is formed.
Further, by contact with the plasma, the first metal film 5a is formed.
The temperature of the sample itself which has formed
About. When RuO4 is generated efficiently, ruthenium is etched, but under the conditions of the oxygen plasma treatment described in this embodiment, ruthenium is not etched, and thus Ru is efficiently removed from the surface as RuO4. It is considered that they are not in the state of separating.

As described above, when the oxygen plasma treatment in the embodiment is performed, RuO 3 and RuO 4 are generated on the surface of ruthenium by active oxygen, so that the oxides of these ruthenium are removed from the surface of ruthenium. Is released, but due to its instability Ru soon
It is considered that a reaction returning to a stable state such as O2 occurs, and through this reaction, rearrangement occurs on the surface as Ru atoms become RuO2. FIG. 2 is a photograph showing a state when the surface of the first metal film 5a is observed with an electron microscope. FIG. 2A is a photographic view showing a state in which the surface of the first metal film 5a is observed with an electron microscope before the first metal film 5a is subjected to the oxygen plasma treatment, and FIG. Of the first metal film 5a after oxygen plasma treatment
FIG. 4 is a photograph showing a state when the surface of the metal film 5a of FIG.

The sample used in the present embodiment has a crystal structure, and RuO2 can also have a crystal structure. Therefore, in the rearrangement of RuO2, the sample is easily rearranged depending on the ruthenium crystal. Is present, and at that point, growth by RuO2 rearrangement occurs selectively, so that it is considered that irregularities occur on the surface of ruthenium. Next, after depositing the high dielectric film 7 by a CVD method or the like, a second metal film is formed by a sputtering method or a CVD method. Through the steps described above, the capacitor of the semiconductor device is formed.

As described above, in this embodiment,
Since there is a step of exposing the first metal film 5a to oxygen plasma, growth by rearrangement occurs on the surface of the first metal film 5a, so that irregularities are formed on the surface. By forming irregularities on the surface of the first metal film 5a, the surface area of the first metal film 5a and the surface area of the second metal film 8 facing the first metal film 5a become larger than before. Therefore, even if the height h of the first metal film is made smaller than before, it is possible to obtain the same surface area as before. Therefore, since the step of the capacitor can be made smaller than before, it is possible to reduce the inconvenience of the manufacturing process due to the step caused by the thickness of the capacitor in the step of depositing a film above this capacitor. Becomes

In this embodiment, in the oxygen plasma treatment, the pressure of the oxygen plasma is set to 1 (Torr), but it is not necessary to limit to this value, and the pressure is set to 0.1 (Torr).
It was found that when the pressure was set to 10 to 10 (Torr), the rearrangement of the surface of ruthenium as the first metal film progressed, and irregularities were formed on the surface.

In this embodiment, the temperature of the sample is set at 150 (° C.) to 200 (° C.) in the oxygen plasma treatment.
However, the present invention is not limited to this. Even in the range of room temperature to 400 (° C.), the rearrangement of the surface of the ruthenium as the first metal film proceeds, and irregularities are formed on the surface. I understand.

In this embodiment, the first metal film 5
a, the material of the second metal film 8 is ruthenium; however, the material is not limited thereto, and the first metal film 5a and the second metal film 8 contain ruthenium dioxide and ruthenium. Even if a metal or a metal containing ruthenium dioxide is used, recrystallization proceeds on the surface of the first metal film, and irregularities are formed on the surface. In this embodiment, a method for manufacturing a capacitor of a semiconductor device has been described. However, the present invention can be applied to a method for manufacturing a capacitor.

[0033]

According to the method of manufacturing a capacitor according to the present invention, since the step of exposing the surface of the first metal film to oxygen plasma is provided, the step of the capacitor can be made smaller than before. Therefore, in the step of depositing a film above the capacitor, it is possible to reduce the inconvenience of the manufacturing process due to the step of the capacitor.

According to the method of manufacturing a capacitor according to the present invention, in the step of exposing the surface of the first metal film to oxygen plasma, the pressure of the oxygen plasma is set to 0.1 (Torr) to 1 (Torr).
0 (Torr), rearrangement occurs on the surface of the first metal film, and irregularities are formed. Therefore, in the step of depositing the film above the capacitor, the manufacturing process is caused by the step of the capacitor. Inconvenience of the process can be reduced.

According to the method of manufacturing a capacitor according to the present invention, in the step of exposing the surface of the first metal film to oxygen plasma, the temperature of the first metal film is changed from room temperature to 400 (° C.). Since the rearrangement occurs on the surface of the first metal film and the unevenness is formed, it is possible to reduce the inconvenience of the manufacturing process due to the step of the capacitor in the step of depositing the film above the capacitor. Becomes

According to the method of manufacturing a capacitor according to the present invention, even if the first metal film is made of ruthenium dioxide, a metal containing ruthenium, or a metal containing ruthenium dioxide, the surface of the first metal film is exposed to oxygen plasma. Thereby, since irregularities can be formed on the surface, in the step of depositing a film above the capacitor, it is possible to reduce the inconvenience of the manufacturing process due to the step of the capacitor.

According to the method of manufacturing a capacitor of a semiconductor device according to the present invention, since the step of exposing the surface of the first metal film made of ruthenium to oxygen plasma is included, the thickness of the capacitor can be made smaller than before. Therefore, in the process of depositing a film above the capacitor, it is possible to reduce the inconvenience of the manufacturing process due to the step caused by the thickness of the capacitor.

According to the method of manufacturing a capacitor of a semiconductor device according to the present invention, in the step of exposing the surface of the first metal film to oxygen plasma, the pressure of oxygen plasma is reduced to 0.1.
(Torr) to 10 (Torr), rearrangement occurs on the surface of the first metal film, and unevenness is formed. In the step of depositing the film above the capacitor, the step is caused by the step of the capacitor. The inconvenience of the manufacturing process can be reduced.

According to the method of manufacturing a capacitor of a semiconductor device according to the present invention, in the step of exposing the surface of the first metal film to oxygen plasma, the temperature of the first metal film is changed from room temperature to 400 (° C.). As a result, rearrangement occurs on the surface of the first metal film, and irregularities are formed. In the process of depositing the film above the capacitor, the inconvenience of the manufacturing process due to the step of the capacitor is reduced. It is possible to do.

According to the method of manufacturing a capacitor of a semiconductor device according to the present invention, the first metal film is made of ruthenium dioxide, a metal containing ruthenium, or a metal containing ruthenium dioxide. By exposing the surface to oxygen plasma, rearrangement occurs on the surface of the first metal film, and irregularities can be formed on the surface of the first metal film. Therefore, a step of depositing a film above the capacitor In this case, it is possible to reduce the inconvenience of the manufacturing process caused by the step of the capacitor.

According to the capacitor of the semiconductor device according to the present invention, since the crystal structure of the surface of the first metal film is rearranged, irregularities are formed on the surface.
Since the surface area is larger than that having a smooth surface, the thickness of the first metal film can be reduced, so that the device can be made thinner.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method of manufacturing a capacitor of a semiconductor device according to a first embodiment;

FIG. 2 is a photograph of the surface of the first metal film taken with an electron microscope in the first embodiment.

FIG. 3 is a diagram illustrating a structure of a capacitor of the semiconductor device according to the first embodiment;

[Explanation of symbols]

 1: substrate 2: silicon oxide film 3: hole 4: conductive member 5, 5a: first metal film 7: high dielectric film 8: second metal film

Claims (9)

[Claims] 1. A method for manufacturing a capacitor, comprising: (a) exposing a surface of a ruthenium-containing first metal film to oxygen plasma; and (b) forming a dielectric on the first metal film. (C) a step of forming a second metal film containing ruthenium on the dielectric material. 2. In the step of exposing the surface of the first metal film to oxygen plasma, the pressure of the oxygen plasma is set to 0.1 (Torr).
The method according to claim 1, wherein r) to 10 (Torr). 3. The step of exposing the surface of the first metal film to oxygen plasma, wherein the temperature of the first metal film is from room temperature to 4 degrees.
2. The temperature is set to 00 (° C.).
3. The method for manufacturing a capacitor according to any one of 2. 4. The method according to claim 1, wherein the ruthenium is ruthenium dioxide. 5. A method for manufacturing a capacitor of a semiconductor device, comprising: (a) forming a conductive member on a substrate. (B) First having ruthenium on the conductive member
(C) exposing the surface of the first metal film to oxygen plasma; (d) forming a dielectric on the first metal film; and (e) forming a dielectric on the first metal film. Forming a second metal film containing ruthenium on the substrate. A method for manufacturing a capacitor of a semiconductor device, comprising: 6. The step of exposing the surface of the first metal film to oxygen plasma, wherein the pressure of the oxygen plasma is 0.1 (Torr).
6. The method for manufacturing a capacitor of a semiconductor device according to claim 5, wherein r) to 10 (Torr). 7. The step of exposing the surface of the first metal film to oxygen plasma, wherein the temperature of the first metal film is between room temperature and 4 ° C.
The temperature is set to 00 (° C.).
7. The method for manufacturing a capacitor of a semiconductor device according to any one of 6. 8. The method for manufacturing a capacitor of a semiconductor device according to claim 5, wherein the ruthenium is ruthenium dioxide. 9. A substrate, a conductive member formed on the substrate, a first metal film having ruthenium or ruthenium dioxide formed on the conductive member, and the first metal film And a second metal film having ruthenium or ruthenium dioxide formed on the dielectric. A capacitor of a semiconductor device, comprising: a crystal on a surface of the first metal film; A capacitor for a semiconductor device, wherein the structure is rearranged.