JPH0878397A - Method for etching film containing high-meltingpoint metal and production of thin-film capacitor - Google Patents

Abstract

PURPOSE: To etch the lower electrode of a thin-film capacitor to make it tapered. CONSTITUTION: The surface of a silicon substrate 1 is oxidized to obtain a silicon oxide film 2 and a lower platinum electrode film 3 is formed thereon, then a photo-resist pattern 5 is further formed as an etching mask thereon. In addition, an etching is applied there to by using a chlorine gas as an etching gas. At that time, a reaction product resulted from etching is adhered to the side wall of the pattern 5, forming a side-wall film 9. The thickness of the film 9 increases as the etching progresses. On the other hand, since the pattern 5 is etched from the square part of its upper end in a tapered shape, the film 9 is shifted to the lower part of the pattern 5 with the progress of etching and the thickness thereof increases furthermore. As a result, the film 3 is tapered in a manner to have a taper angle 4 through etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for etching a refractory metal-containing film and a method for manufacturing a thin film capacitor for a semiconductor device using the refractory metal-containing film.

[0002]

2. Description of the Related Art The background of the present invention is exemplified by a semiconductor device using a multi-element oxide film having a high dielectric constant (hereinafter referred to as a multi-element oxide high dielectric constant film) as a dielectric of a thin film capacitor element. explain.

In the above semiconductor device, platinum, which is one of the refractory metal-containing films, is used as the electrode material of the thin film capacitor. In the case of a semiconductor device having a fine structure such as DRAM, at least the capacitor is used. It is necessary to perform fine processing on one side of the platinum electrode (hereinafter, the electrode on the side to be finely processed is referred to as a lower electrode). Therefore, dry etching using reactive gas plasma (an anisotropic method such as reactive ion etching) is required. Etching of the platinum film is performed. In this case, since the vapor pressure of the reaction product of platinum etching is low, it is necessary to utilize the effect of sputtering by ions, and as a result, the etching shape of the platinum film becomes vertical.

After etching the platinum electrode, a multi-element oxide high dielectric constant film which is a dielectric of the capacitor is formed on the platinum electrode. Since this multi-element oxide high dielectric constant film is currently formed by the sputter deposition method, the coverage at the step portion of the platinum electrode end caused by etching is poor, and the multi-element oxide film on the side surface of the platinum electrode is poorer than that on the platinum electrode upper surface. The film thickness of the high dielectric constant film becomes extremely thin. This state is shown in the sectional view of FIG. In the figure, 3P is the lower electrode of the platinum electrode, 7
P is a multi-element oxide high dielectric constant film, and 8P is an upper electrode of a platinum electrode.

As a new deposition method replacing the sputter deposition method, a deposition method of a multi-element oxide high dielectric constant film by CVD can be considered, but even in this case, there is a tendency that the side surface of the platinum electrode 3P becomes thin ( (See FIG. 17).

After the deposition of the multi-component oxide high dielectric constant film 7P, the upper platinum electrode 8 which is the other electrode of the capacitor is formed.
As P, a platinum film is formed on the multi-element oxide high dielectric constant film 7P (see FIG. 16).

In the fine thin film capacitor formed as described above, the capacitance of the capacitor is small because it is fine, but the capacitance of the capacitor is reduced by thinning the multi-element oxide high dielectric constant film that is a dielectric. Reserved. However, when the film thickness of this multi-element oxide high dielectric constant film becomes thin, the film thickness cannot be extremely thinned because the leak current flowing through the film increases, and as a result,
The film thickness of the multi-element oxide high-dielectric constant film can be reduced with a film thickness that can obtain the minimum required capacitance of the capacitor.

[0008]

The above-described conventional method for forming a fine thin film capacitor using a multi-element oxide high dielectric constant film and a platinum film has the following problems.

A multi-element oxide high dielectric constant film having a thickness determined so as to obtain a desired capacitance of a capacitor is formed on a platinum electrode (lower electrode) whose electrode end is vertically etched. Due to the poor coverage of the multi-element oxide high dielectric constant film at the stepped portion at the electrode end, the film thickness becomes thinner than the determined film thickness on the side surface of the electrode. Current leakage will occur in this thinned portion, and the entire capacitor will leak more current than is expected from the thickness of the predetermined multi-element oxide high dielectric constant film. become. Therefore, in order to prevent this, it is necessary to increase the film thickness of the multi-element oxide high dielectric constant film, and as a result, there arises a problem that the desired capacitance of the capacitor cannot be obtained.

As a method for avoiding the above problem, after forming the lower platinum electrode, an insulating film such as a silicon oxide film is formed on the entire surface, and the entire surface is etched by anisotropic etching to obtain the lower platinum. A method has been proposed in which a spacer made of an insulating film is formed on the side surface of an electrode to prevent current leakage due to local thinning on the side surface of the electrode.

However, even in this method, the following problems occur. In other words, due to the controllability problem when forming the spacer, the upper end of the spacer falls below the platinum electrode end, and there is a steep step due to vertical processing of the platinum electrode in this part, and the material of the platinum film and the insulating film. Discontinuity surface occurs. This state is shown in the sectional view of FIG. In the figure, 6P is a spacer. When the multi-element oxide high-dielectric-constant film 7P is formed on such a step portion, the film quality becomes abnormal at this portion, and current leakage occurs.
Therefore, this method also has a problem that a thin film capacitor having desired performance cannot be obtained.

The present invention has been made in view of the above problems, and prevents leakage of current generated on the side surface of a refractory metal-containing film as a lower electrode of a thin film capacitor,
It is intended to realize a high-performance thin film capacitor, and a new etching method for a refractory metal-containing film for that purpose and a method for manufacturing a thin film capacitor using the etching method are provided.

[0013]

The invention according to claim 1 is
A method of etching a refractory metal-containing film formed on an underlayer using a photoresist pattern formed on the refractory metal-containing film as a mask, wherein chlorine gas is introduced as a reaction gas for the etching, The refractory metal-containing film is etched.

According to a second aspect of the present invention, in the method for etching a refractory metal-containing film according to the first aspect, instead of the chlorine gas, a mixed gas of a rare gas and the chlorine gas is used as a reaction gas for the etching. I am using.

According to a third aspect of the present invention, in the method for etching a refractory metal-containing film according to the second aspect, Ar gas,
A gas containing at least one of Kr gas and Xe gas is used as the rare gas.

According to a fourth aspect of the present invention, in the method for etching a refractory metal-containing film according to the first aspect, a mixed gas of a rare gas and a halogen compound gas is used as a reaction gas for the etching instead of the chlorine gas. I am using.

The invention according to claim 5 is the method for etching a refractory metal-containing film according to claim 4, wherein Ar gas,
A gas containing at least one of Kr gas and Xe gas is used as the rare gas, while CF4 gas and CHF3 are used.
Gas, SF6 gas, NF3 gas, HCl gas and HBr
A gas containing at least one of the gases is used as the halogen compound gas.

According to a sixth aspect of the present invention, there is provided a method of etching a refractory metal-containing film formed on an underlayer using a photoresist pattern formed on the refractory metal-containing film as a mask. The film is etched into a vertical shape, the photoresist pattern is removed after the etching, and the refractory metal-containing film is etched again using a rare gas as an etching gas after the removal.

The invention according to claim 7 is the method for etching a refractory metal-containing film according to claim 6, wherein Ar gas,
A gas containing at least one of Kr gas and Xe gas is used as the rare gas.

The invention according to claim 8 is the method for etching a refractory metal-containing film according to any one of claims 1 to 7, wherein the refractory metal-containing film comprises a refractory metal and a refractory metal compound. It contains either one.

The invention according to claim 9 is the method for etching a refractory metal-containing film according to claim 8, wherein the refractory metal is platinum, palladium, iridium, gold, ruthenium, rhenium, osmium or rhodium. It is a metal containing at least one kind, and the refractory metal compound is one of silicide and oxide of the refractory metal.

A tenth aspect of the present invention is the method for etching a refractory metal-containing film according to any one of the first to fifth aspects, wherein the sidewall of the photoresist pattern is formed on the sidewall of the photoresist pattern after the etching. The photoresist pattern is removed together with the attached sidewall adhesion film.

The invention according to claim 11 is a method of manufacturing a thin film capacitor using the etching method according to claim 6 or 10, wherein the high melting point is obtained by the etching method according to claim 6 or 10. A step of etching the metal-containing film into a taper shape, and forming a multi-element oxide high dielectric constant film on the taper-shaped high-melting point metal-containing film, and further forming a multi-element oxide high dielectric constant film And a step of forming another refractory metal-containing film.

The invention according to claim 12 is the method of manufacturing a thin film capacitor according to claim 11, wherein an insulating film is formed on the tapered side surface of the refractory metal-containing film after etching the refractory metal-containing film. After forming a spacer made of, the multi-element oxide high dielectric constant film is formed.

[0025]

[Action]

(Invention of Claim 1) When etching is performed with chlorine gas, the reaction product of the etching adheres to the side wall of the photoresist pattern to form an inclined side wall adhering film. Moreover, the photoresist pattern is etched in a taper shape from the upper corner portion. Along with the change in the shape of the photoresist pattern, the formation position of the side wall adhesion film moves to the lower part of the photoresist pattern, and in the lower part, the thickness of the side wall adhesion film is further increased by etching. As a result, the sidewall adhesion film is
It functions as an etching mask inclined at a smooth angle with respect to the sidewall of the photoresist pattern.

(Invention of Claim 2) Part of the refractory metal-containing film removed during the etching with the rare gas adheres to the vertical sidewall of the photoresist pattern to form a sidewall adhesion film. In addition, the reaction product of the etching by chlorine gas also adheres to the sidewall of the photoresist pattern, and the film of the reaction product also constitutes the above-mentioned sidewall film. At the same time, by etching with chlorine gas, the photoresist pattern is etched in a taper shape from the upper corner portion. As a result, the formation position of the side wall adhering film moves to the lower part of the photoresist pattern, and further etching in the lower part increases the thickness of the side wall adhering film and also increases its inclination angle. As a result, the sidewall adhesion film functions as an etching mask inclined at a smooth angle with respect to the sidewall of the photoresist pattern. At that time, depending on the mixing amount of chlorine gas,
The shape change of the photoresist pattern also changes, and the inclination of the sidewall adhesion film changes accordingly.

(Invention of Claim 3) Ar gas, Kr
Gas and a gas containing at least one of Xe gas,
It functions as a reaction gas for etching.

(Invention of Claim 4) A part of the refractory metal-containing film removed during the etching with the rare gas adheres to the vertical sidewall of the photoresist pattern to form a sidewall adhesion film. At the same time, the photoresist pattern is also etched from the upper corners of the photoresist pattern. Moreover, the etching rate of the photoresist pattern increases under the influence of the halogen compound gas,
The product produced by this etching is taken into the above-mentioned side wall adhesion film already produced by the rare gas. Therefore, the sidewall adhesion film moves to the lower portion of the photoresist pattern while increasing its thickness as the etching progresses, and further increases the thickness at the lower portion. As a result, the sidewall adhesion film functions as an etching mask having a shape inclined with respect to the sidewall of the photoresist pattern.

(Invention of Claim 5) Ar gas, Kr
The gas containing at least one of the gases and Xe gas functions as a rare gas, while CF4 gas, CHF3 gas,
A gas containing at least one of SF6 gas, NF3 gas, HCl gas, and HBr gas functions as a halogen compound gas.

(Invention of Claim 6) After the photoresist pattern is removed, the refractory metal-containing film is formed in a shape vertical to the base. If the refractory metal-containing film is further etched with a rare gas in this state, the etching rate at the corners of the refractory metal-containing film becomes particularly faster than at other parts, so the corners at the top of the refractory metal-containing film are Portions are selectively etched. As a result, the end portion of the refractory metal-containing film has a tapered shape.

(Invention of Claim 7) Ar gas, Kr
Gas and a gas containing at least one of Xe gas,
Functions as a rare gas.

Etching method.

(Invention of Claim 8) A refractory metal-containing film containing either a refractory metal or a refractory metal compound is taper-etched.

(Invention of Claim 9) Any of refractory metal containing at least one of platinum, palladium, iridium, gold, ruthenium, rhenium, osmium and rhodium, or silicide or oxide of refractory metal. The refractory metal compound, which is on the other hand, is taper-etched.

(Invention of Claim 10) By removing the photoresist pattern, a smoothly inclined refractory metal-containing film is formed on the base.

(Invention of Claim 11) A multi-element oxide high dielectric constant film having a uniform film thickness is formed on a refractory metal-containing film that is etched into a tapered shape, and the multi-element oxide high dielectric constant film is formed. Another refractory metal-containing film is formed on the index film to have a uniform film thickness.

(Invention of Claim 12) A spacer is formed at an end of a refractory metal-containing film etched into a taper shape, and a multi-layered film having a uniform film thickness is formed on the refractory metal-containing film and the spacer. A high-dielectric-constant oxide film is formed, and another refractory metal-containing film having a uniform thickness is formed on the multi-element high-dielectric oxide film.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The essence of the problem occurring in the prior art is the generation of a sharp step due to the vertical etching of the lower platinum electrode end. Therefore, the present invention provides an etching method for etching the electrode end of the lower refractory metal-containing film (platinum film) into a gently tapered shape instead of a vertical shape. The effect of etching the lower electrode made of the high melting point metal-containing film into a tapered shape is as follows.

In the case of depositing a multi-element oxide high dielectric constant film on the lower electrode of the refractory metal-containing film which is etched in a tapered shape by the sputter deposition or the CVD method,
The difference in film thickness between the lower electrode of the refractory metal-containing film and the side surface of the lower electrode is reduced as compared with the case of the conventional technique in which the lower electrode is etched into a vertical shape. This makes it possible to use thinner multi-element oxide high-k films as the whole thin film capacitor, and as a result, it is possible to form a thin film capacitor with less leakage current and larger capacitance than the conventional method. Becomes

A cross-sectional view of a thin film capacitor formed according to the present invention is shown in FIG. In the figure, 3 and 8 are the lower electrode and the upper electrode of the refractory metal containing film, respectively, and the platinum film is used in each of the following examples. Therefore, in the following examples, 3 is referred to as a lower platinum electrode film (or simply platinum film), and 8 is referred to as an upper platinum electrode film. Reference numeral 7 denotes a multi-element oxide high dielectric constant film, for example, a barium-strontium-titanium oxide film (so-called BST film) or a strontium-titanium oxide film (STO film).

Further, in the method of forming the spacer made of the insulating film on the side surface of the lower electrode of the refractory metal containing film, the lower electrode is etched into a taper shape so that the space between the lower electrode end and the spacer upper end is formed. The step and the steepness thereof can be reduced as compared with the case of the conventional technique in which the lower electrode is vertically etched.
Therefore, it is possible to prevent the film quality abnormality of the multi-element oxide high dielectric constant film at that portion, and reduce the current leakage of the entire thin film capacitor. The structure of the thin film capacitor in this case is shown in the sectional view of FIG. In the figure, 6 is a spacer.

Examples of the method for etching a refractory metal-containing film and the method for manufacturing a thin film capacitor using the same according to the present invention will be described below using a platinum film as the refractory metal-containing film as an example.

First, an example of an etching apparatus used in each embodiment of the present invention is shown in the vertical sectional view of FIG. In the etching processing chamber 10, a reaction gas inlet 11, an exhaust port 12 connected to a vacuum pump for exhausting the reaction gas from the etching processing chamber 10, a cathode electrode 13 for applying RF power for discharging, and An anode electrode 14 that is electrically grounded is provided. Further, outside the etching processing chamber 10, there is provided an electromagnetic coil 15 capable of applying a magnetic field to the discharge region in order to enhance discharge.

First, the sample 16 to be etched is placed on the cathode electrode 13, and the etching processing chamber 10 is evacuated to a vacuum through the exhaust port 12. While continuing the exhaust, the etching gas is introduced from the gas inlet 11 and the etching processing chamber 10 is maintained at a predetermined pressure. Therefore, RF power and a magnetic field are applied to the cathode electrode 13 by an electromagnetic coil to start discharge in the etching processing chamber 10 and the sample 6 is etched.

The above-described etching apparatus is an example of the etching apparatus used in each of the embodiments of the present invention, and the present invention can be implemented by etching apparatuses of other types.

An example of the etching sample 16 used in each embodiment of the present invention is shown in the sectional view of FIG. In the figure, the silicon oxide film 2 is formed by oxidizing the surface of the silicon substrate 1.
Then, the platinum film 3 is formed by the sputter deposition method. A mask for etching processing is formed by transferring a pattern to an organic photoresist film. In the same figure, a photoresist pattern 5 formed perpendicular to the platinum film 3 after pattern transfer is shown. The sample 16 described above is an example of the sample used in this etching, and the present invention can be implemented even when the base of the platinum film 3 is other than the silicon oxide film 2. For example, an insulating film such as a silicon nitride film may be used as a base, and further, a film in which a barrier metal (barrier layer) is formed on these insulating films may be used as a base.

Each embodiment of the present invention will be described below in sequence. In each drawing referred to in the description of each embodiment, the same reference numeral or the same reference numeral with an alphabet indicates the same thing.

Example 1 When chlorine gas is used as a reaction gas for etching, the platinum film is etched into a tapered shape. The progress of this etching is shown in FIGS.

When the platinum film 3 is etched with chlorine gas (FIG. 5), since the vapor pressure of the reaction product of the etching is extremely low, the reaction product is regenerated on the sidewall of the photoresist pattern 5 which is the etching mask. Adhere to form the side wall adhering film 9 (FIG. 6). The thickness of the side wall adhesion film 9 increases with the progress of etching (FIG. 7).

On the other hand, when the etching gas is chlorine, the photoresist pattern 5 is etched in a taper shape from the upper corner portion (FIGS. 6 and 7). Then, due to the change in shape of the photoresist pattern 5 during etching, the formation position of the sidewall adhesion film 9 moves to the lower part of the photoresist pattern 5 (FIG. 7). In the lower part of the photoresist pattern 5, the thickness of the side wall adhesion film 9 increases as the etching progresses, but the side wall adhesion film 9 also acts as an etching mask for the platinum film 3 (FIGS. 6 to 7). ) As a result, the platinum film 3 is etched into a taper shape having a taper angle 4 (FIG. 8).

After the platinum film 3 has been etched, the photoresist pattern 5 is removed by ashing and the side wall adhesion film 9 is removed. A mechanical treatment can be used as a method for removing the sidewall adhesion film 9. For example,
A so-called brush scrubber method of rotating the brush to remove the film 9 can be used. Thereby, the platinum electrode 3 (lower electrode) etched in a tapered shape is obtained. Table 1 below shows an example of the discharge conditions and the taper angle 4 when this taper etching is obtained.

[0052]

[Table 1]

After that, the multi-element oxide high dielectric constant film 7 and the upper electrode 8 of the platinum film are formed by the sputtering method to form a thin film capacitor. Both films 7 and 8 are smoothly formed in a tapered shape along the tapered shape of the lower electrode 3.

(Embodiment 2) Here, a case will be described where etching is performed using a mixed gas of a rare gas and chlorine gas as a reaction gas for etching. Also in this case, the platinum film is etched in a taper shape, and the angle of the taper shape of the etched platinum film can be changed depending on the concentration of chlorine mixed. In the second embodiment, the progress of etching caused by the difference in the mixing ratio is shown in the sectional views of FIGS.

When only a rare gas is used as the etching gas, the platinum film 3A is etched by sputtering, and thus the platinum film 3A that has been sputter-removed is reproduced on the vertical side surface of the photoresist pattern 5A which is the etching mask. It adheres to form a redeposition film 9A. Since the redeposition film 9A increases in thickness as the platinum film 3A is etched, the etching shape of the etched platinum film 3A is not a perfect vertical shape but a shape having a slight taper angle.

When chlorine gas is mixed in the etching with the rare gas, the photoresist pattern 5A is changed in shape into a taper shape during the etching with chlorine gas by the mechanism described in the first embodiment, and the photoresist pattern 5A is changed. The deposition position of the side wall deposits 9A of the platinum film 3 moves to the lower side wall of the photoresist pattern 5A.
A is etched into a taper shape.

When the amount of chlorine gas mixed is changed, the degree of shape change of the photoresist pattern 5A during etching is changed, and as a result, the taper angle 4A of the platinum film 3A to be etched is changed. To do. That is, the taper angle 4A of the platinum film 3A to be etched can be changed by changing the amount of chlorine gas mixed with the rare gas. This point
This is a feature of the etching method in the second embodiment.

Specifically, when the chlorine gas to be mixed is small, the taper angle 4A is large (FIG. 9), and conversely, when the chlorine gas to be mixed is large, the taper angle 4A is small (FIG. 10).

Taking as an example of the conditions that can realize the above etching, using Ar as a rare gas, the discharge conditions and the resulting taper angle 4A of etching are shown in Tables 2 and 3 below. Becomes

[0060]

[Table 2]

[0061]

[Table 3]

Here, Table 3 shows the relationship between the mixing amount of chlorine gas and the taper angle 4A of the platinum film 3A.

When the taper etching of the lower platinum electrode film 3A is completed, the photoresist pattern 5A and the side wall deposits 9A are removed, and the lower platinum electrode film 3A is then removed.
The multi-element oxide high dielectric constant film 7 and the upper platinum electrode film 8 are deposited in this order on the both films 7 and 8 to form a thin film capacitor.

Example 3 In Example 3, etching is performed using a mixed gas of a rare gas and a halogen compound gas as a reaction gas for etching. Also in this case, the platinum film is etched in a taper shape, and the angle of the taper shape of the platinum film to be etched can be changed depending on the kind and concentration of the mixed halogen compound gas. The progress of the etching in the third embodiment is
It is shown in the sectional views of FIGS.

Here, when only a rare gas is used as the etching gas, the etching shape of the etched platinum film 3B is not a perfect vertical shape but is slightly tapered due to the mechanism described in the second embodiment. The shape has an angle 4B (FIG. 11).

Therefore, when a halogen compound gas is mixed in the etching with the rare gas, the etching rate of the photoresist pattern 5B as the etching mask is increased due to the influence of the halogen compound gas, and the product of the etching is the platinum film 3B. Are taken into the adhering film 9B on the side wall of the photoresist pattern 5B generated by the above etching, and the film thickness of the side wall adhering film 9B is increased. As a result, when the halogen compound gas is mixed, the taper shape of the platinum film 3B to be etched becomes stronger and the taper angle 4B becomes smaller than that when etching is performed using only the rare gas (FIG. 12). Further, since the etching rate of the photoresist pattern 5B also changes depending on the kind of the halogen compound gas mixed, the platinum film 3B to be etched is
The angle 4B of the taper shape also changes.

As an example of the conditions under which the above etching can be realized, Ar is used as a rare gas, and HBr, CF4, and SF6 are used as halogen compound gases, respectively. The discharge conditions and the etching taper obtained at that time are taken as examples. The angle 4B is shown in the following Tables 4 and 5 (relationship between kinds of halogen compound gas to be mixed and taper angle of platinum film).

[0068]

[Table 4]

[0069]

[Table 5]

After that, a thin film capacitor is formed through the same process as in the first and second embodiments.

Example 4 The progress of etching in Example 4 is shown in FIGS. 13 to 15.

First, the platinum film 3C is etched into a vertical shape by the same method as the conventional technique (FIG. 13). That is, A
The platinum film 3C is vertically etched by anisotropic etching such as etching with an inert gas such as r.
Then, after removing the photoresist pattern 5C which is the etching mask (FIG. 14), etching is performed using a rare gas. As a result, the etching shape of the platinum film 3C can be changed from the vertical shape to the tapered shape (FIG. 15).

In etching using a rare gas, the platinum film is etched by sputtering, and the etching rate by this sputtering is particularly high at the corners of the surface to be etched. When the etching having the above properties is applied to the vertically-etched platinum film 3C after removing the photoresist pattern 5C, the corners at the upper end of the vertical shape are selectively etched and 45 degrees to 60 degrees. It changes into a tapered shape having an angle of degrees (FIG. 14 → FIG. 15).

Table 6 below shows an example of the discharge conditions and the taper angle when such etching is obtained, using Ar as the rare gas as an example.

[0075]

[Table 6]

Thereafter, the platinum film 3C having a tapered shape is formed.
A multi-component oxide high-dielectric constant film 7 is deposited thereon, and an upper platinum electrode film 8 is further deposited on the multi-component oxide high-dielectric constant film 7. As a result, both films 7 and 8 are deposited with a uniform film thickness (FIG. 1), and a thin film capacitor capable of suppressing the generation of leak current is formed.

(Modification 1) In Examples 2 to 4,
Although Ar gas was used as the rare gas, the present invention is not limited to this. That is, as a modification of these examples, it is possible to apply Kr gas or Xe gas as a rare gas instead of Ar gas, and further, at least two kinds of Ar gas, Kr gas and Xe gas may be used. It is also possible to apply the mixed gas containing it as a rare gas. In this case, the same effect can be obtained.

(Modification 2) In Example 3, HBr gas, CF4 gas, or SF is used as the halogen compound gas.
Although any of the six gases was used, the present invention is not limited to these gases. That is, instead of applying these gases, CHF3 gas, NF3 gas, HCl
The gas can also be applied as the halogen compound gas. Furthermore, the above CF4 gas, CHF3 gas, S
A mixed gas containing at least two of F6 gas, NF3 gas, HCl gas, and HBr gas may be used as the halogen compound gas. Similar effects can be obtained in these cases as well.

(Modification 3) In each of Examples 1 to 4, the platinum film was used as the refractory metal-containing film, but the present invention is not limited to the platinum film. That is, instead of the platinum film, a film containing any one refractory metal of palladium, iridium, gold, ruthenium, rhenium, osmium, or rhodium can be used as the refractory metal-containing film. Further, a refractory metal film containing at least two kinds of platinum, palladium, iridium, gold, ruthenium, rhenium, osmium and rhodium can also be used. Also in these modified examples, the first embodiment
-The effect obtained in Example 4 can be exhibited.

(Modification 4) In each of Examples 1 to 4 and Modification 3, a film containing a refractory metal was used as the refractory metal-containing film. A refractory metal compound composed of either a metal silicide or an oxide may be used as the refractory metal-containing film. Similar effects can be obtained in these cases as well.

(Modification 5) In each of Examples 1 to 4 and Modifications 1 to 4, the thin film capacitor shown in FIG. 1 was manufactured after taper etching. However, the taper etching method disclosed in each of Examples 1 to 4 and Modifications 1 to 4 can be applied to the manufacture of the thin film capacitor shown in FIG.

By the etching method and the method of forming a thin film capacitor using the etching method shown in each of the above embodiments and modifications, the capacitor has a larger capacitance and a smaller leak current than the conventional etching method. It is possible to form a thin film capacitor. As a result, it is possible to further promote the thinning of the thin film capacitor, and it is possible to contribute to downsizing or higher performance of the semiconductor device.

[0083]

According to the invention of claim 1, the end portion of the refractory metal-containing film formed as the base can be etched into a tapered shape. This can reduce the steepness of the step at the end of the refractory metal-containing film, and when the refractory metal-containing film is used as the lower electrode of the thin film capacitor, it is formed on the refractory metal-containing film. It is possible to reduce the film thickness difference between the upper high-melting-point metal-containing film and the side surface of the end of the high-dielectric-constant film, so that a high-dielectric-constant film having a smaller film thickness can be used.

According to the second aspect of the present invention, not only the edge of the refractory metal-containing film can be etched into a tapered shape, but also the refractory metal etched by changing the amount of chlorine gas mixed with the rare gas. The taper angle of the contained film can be changed. That is, there is an effect that the taper angle of the end portion of the refractory metal-containing film can be controlled by the mixing amount of chlorine gas.

According to the third aspect of the invention, there is an effect that the end portions of the refractory metal-containing film can be etched into a taper shape by using various kinds of rare gases or mixed gases thereof.

According to the invention of claim 4, the end of the refractory metal-containing film can be etched into a tapered shape having a small taper angle, and the kind of halogen compound gas mixed with the rare gas and its The taper angle of the refractory metal-containing film to be etched can be changed by changing the concentration. That is, there is an effect that the taper angle of the end portion of the refractory metal-containing film can be controlled by the kind and concentration of the halogen compound gas.

According to the invention of claim 5, a combination of various kinds of rare gases or their mixed gases and various kinds of halogen compound gases or their mixed gases is used to contain the refractory metal. The edge of the film can be etched into a tapered shape, and the taper angle can be changed to various angles.

According to the invention of claim 6, there is an effect that the refractory metal-containing film formed in the vertical shape by the conventional technique can be further etched in a tapered shape at its end. Moreover, in the present invention, the taper etching is realized by using only the rare gas, so that the taper etching technology which is versatile and can effectively utilize the conventional technology can be provided.

According to the invention of claim 7, there is an effect that the end portion of the refractory metal-containing film can be etched into a taper shape by using various kinds of rare gases or mixed gas thereof.

According to the invention of claim 8, taper etching can be realized for a refractory metal-containing film containing either refractory metal or refractory metal compound.

According to the invention of claim 9, taper etching for various refractory metal-containing films can be realized.

According to the tenth aspect of the present invention, it is possible to obtain a refractory metal-containing film in which the end portions are smoothly etched in a taper shape, which is used as a lower portion for a thin film capacitor for preventing the generation of leak current. There is an effect that it can be used as an electrode.

According to the eleventh aspect of the present invention, the leak current generated at the side surface portion of the electrode made of the refractory metal-containing film can be remarkably reduced. Therefore, the determined refractory metal-containing film is obtained. It is possible to realize a thin film capacitor having a capacitance as expected from the film thickness of. As a result, the leak characteristic and the capacitance characteristic of the thin film capacitor can be improved.

In addition, by suppressing the leak current, it is possible to use a thinner multi-element oxide high dielectric constant film as compared with the prior art, and it is possible to realize a thin film capacitor having a larger capacitance value. Moreover, the fact that the film thickness of the multi-element oxide high dielectric constant film can be made thinner brings an advantage that a desired capacitance value can be realized even if the area of each film is reduced. Therefore, according to the present invention, it is possible to reduce the size and performance of the thin film capacitor.

According to the twelfth aspect of the present invention, it is possible to reduce the step and steepness between the electrode end made of the refractory metal-containing film and the upper end of the spacer, and at the same time, to improve the multi-element oxide high dielectric constant in that portion. Abnormality of the film quality of the rate film can be prevented, and as a result, the current leakage of the entire thin film capacitor can be significantly reduced. For this reason, it is possible to improve the leak characteristic and the capacitance characteristic of the thin film capacitor, and at the same time, it is possible to reduce the size and performance of the thin film capacitor.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a thin film capacitor in the case where a spacer of an insulating film is not used when the taper etching of the present invention is performed.

FIG. 2 is a cross-sectional view showing a structure of a thin film capacitor in the case of using a spacer of an insulating film when the taper etching of the present invention is performed.

FIG. 3 is a sectional view showing an example of an etching apparatus used in each embodiment of the present invention.

FIG. 4 is a cross-sectional view showing an example of an etching sample used in each example of the present invention.

FIG. 5 is a cross-sectional view showing the progress of etching in Example 1.

FIG. 6 is a cross-sectional view showing the progress of etching in Example 1.

FIG. 7 is a cross-sectional view showing the progress of etching in Example 1.

FIG. 8 is a cross-sectional view showing the progress of etching in Example 1.

FIG. 9 is a cross-sectional view showing the etching in the second embodiment when the chlorine gas mixed is small.

FIG. 10 is a cross-sectional view showing etching when a large amount of chlorine gas is mixed in the second embodiment.

FIG. 11 is a cross-sectional view showing etching when etching is performed only with a rare gas in Example 3.

FIG. 12 is a cross-sectional view showing etching when a halogen compound gas is mixed with a rare gas in Example 3.

FIG. 13 is a process drawing showing the etching flow in the fourth embodiment.

FIG. 14 is a process drawing showing the etching flow in the fourth embodiment.

FIG. 15 is a process drawing showing the etching flow in the fourth embodiment.

FIG. 16 is a cross-sectional view showing a structure of a thin film capacitor formed by a conventional method.

FIG. 17 is a cross-sectional view showing the structure of a thin film capacitor formed by another conventional method.

FIG. 18 is a cross-sectional view showing the structure of a thin film capacitor formed by another conventional method.

[Explanation of symbols]

1 silicon substrate, 2 silicon oxide film, 3, 3A, 3
B, 3C lower platinum electrode film, 4, 4A, 4B, 4C taper angle, 5, 5A, 5B, 5C photoresist pattern, 6 spacer, 7 multi-element oxide high dielectric constant film, 8 upper platinum electrode film, 9, 9A, 9B Side wall adhesion film, 10 Etching chamber, 11 Reactant gas inlet,
12 gas exhaust port, 13 cathode electrode, 14 anode electrode, 15 electromagnetic coil, 16 etching sample.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 27/04 C

Claims (12)

[Claims] 1. A method of etching a refractory metal-containing film formed as an underlayer using a photoresist pattern formed vertically on the refractory metal-containing film as a mask, wherein chlorine gas is used as a reaction gas for the etching. A method for etching a refractory metal-containing film, which comprises introducing and etching the refractory metal-containing film with the chlorine gas. 2. The method for etching a refractory metal-containing film according to claim 1, wherein a mixed gas of a rare gas and the chlorine gas is used as a reaction gas for the etching, instead of the chlorine gas. Method for etching refractory metal-containing film. 3. The refractory metal-containing film according to claim 2, wherein a gas containing at least one of Ar gas, Kr gas and Xe gas is used as the rare gas. Method for etching a contained film. 4. The method for etching a refractory metal-containing film according to claim 1, wherein a mixed gas of a rare gas and a halogen compound gas is used as a reaction gas for the etching, instead of the chlorine gas. Method for etching refractory metal-containing film. 5. The method for etching a refractory metal-containing film according to claim 4, wherein a gas containing at least one of Ar gas, Kr gas and Xe gas is used as the rare gas, while CF4 gas, CHF3 gas, A method of etching a refractory metal containing film, wherein a gas containing at least one of SF6 gas, NF3 gas, HCl gas and HBr gas is used as the halogen compound gas. 6. A method of etching a refractory metal-containing film formed as an underlayer using a photoresist pattern formed vertically on the refractory metal-containing film as a mask, wherein the refractory metal-containing film has a vertical shape. Etching, the photoresist pattern is removed after the etching, and the refractory metal-containing film is etched again using a rare gas as an etching gas after the removal. 7. The refractory metal-containing film etching method according to claim 6, wherein a gas containing at least one of Ar gas, Kr gas and Xe gas is used as the rare gas. Method for etching a contained film. 8. The method of etching a refractory metal-containing film according to claim 1, wherein the refractory metal-containing film contains either a refractory metal or a refractory metal compound. A method for etching a refractory metal-containing film, comprising: 9. The method for etching a refractory metal-containing film according to claim 8, wherein the refractory metal is platinum, palladium, iridium,
A metal containing at least one of gold, ruthenium, rhenium, osmium and rhodium, wherein the refractory metal compound is any one of a silicide and an oxide of the refractory metal. Method for etching refractory metal-containing film. 10. The method for etching a refractory metal-containing film according to claim 1, wherein after the etching, the refractory pattern is formed on a sidewall of the photoresist pattern together with a sidewall adhering film attached during the etching. A method of etching a refractory metal-containing film, which comprises removing the photoresist pattern. 11. A method of manufacturing a thin film capacitor using the etching method according to claim 6 or 10, wherein the refractory metal-containing film is tapered by the etching method according to claim 6 or 10. And a step of forming a multi-component oxide high dielectric constant film on the taper-shaped high melting point metal-containing film, and further including another refractory metal containing film on the multi-component oxide high dielectric constant film. A method of manufacturing a thin film capacitor, comprising: a step of forming a film. 12. The method of manufacturing a thin film capacitor according to claim 11, wherein after the refractory metal-containing film is etched, a spacer made of an insulating film is formed on the tapered side surface of the refractory metal-containing film. A method of manufacturing a thin film capacitor, comprising forming the multi-element oxide high dielectric constant film as described above.