JPH11340214A - Manufacturing for semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a dielectric film as a capacitive element in a semiconductor device from erosion caused by an etching gas in a productive process. SOLUTION: An upper electrode platinum film 3 and a dielectric film 2 are dry-etched by a chlorine-containing etching gas. At this time, a large number of chloride atoms, ions or radicals decomposed from an etching gas are stuck to a sidewall part of the upper electrode platinum film 3 and the dielectric film 2 and a surface 7 of an exposed lower electrode platinum film 1. Then, the plasma obtained by discharging fluorine or a fluorine-based gas which tends not to be reactive with water is cast to a substrate 4, so that the attached chlorine atoms are replaced by the fluorine atoms. Thereafter, the lower electrode platinum film is selectively dry-etched and patterned into a capacitive element electrode into a given shape. Instead of irradiation of plasma obtained through the use of a fluorine-containing gas, a substrate 4 needs only to be heated to remove the chlorine atoms.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor for finely processing a dielectric film of a capacitive element having a high dielectric film or a ferroelectric film as a capacitive insulating film built in a chip of a semiconductor integrated circuit by dry etching. The present invention relates to a device manufacturing method.

[0002]

2. Description of the Related Art In recent years, as semiconductor devices have been miniaturized,
A microcomputer with a built-in capacitive element that uses a high-dielectric film as a capacitive insulating film, which is effective in reducing unnecessary radiation that is electromagnetic wave noise, and a ferroelectric non-volatile RAM that can operate at low voltage and that can write and read at high speed Development is active. Etching of these high dielectric films or ferroelectric films has been performed by wet etching which is isotropic etching or ion milling without selectivity. However, since these methods cannot realize high processing accuracy and high etching selectivity, research and development of dry etching technology have been actively conducted in recent years. An etching gas used for dry etching of a high-dielectric film or a ferroelectric film is mainly halogen represented by chlorine or a compound thereof, and chlorine alone, hydrogen chloride, carbon chloride, and the like have been reported.

Hereinafter, a conventional method for manufacturing a semiconductor device will be described with reference to the drawings.

FIGS. 4A to 4D are process sectional views showing a conventional method of manufacturing a semiconductor device. First, as shown in FIG. 4A, a platinum film 1 for a lower electrode and a high dielectric film are formed. Alternatively, a ferroelectric film (hereinafter, referred to as a dielectric film) 2 and a platinum film 3 for an upper electrode are formed on a substrate 4 on which a silicon oxide film is deposited. Next, the platinum film 3 for the upper electrode and the dielectric film 2 are dry-etched using the photoresist film 5 as a mask and using an etching gas containing chlorine as shown in FIG. Finally, the lower electrode platinum film 1 is dry-etched to form a capacitor.

[0005]

However, in the above-mentioned conventional manufacturing method, the etched platinum film 3 for the upper electrode, the side wall 6 of the dielectric film 2 and the surface 7 of the platinum film 1 for the lower electrode exposed by dry etching. A large amount of chlorine atoms, ions or radicals generated by the decomposition of the etching gas by the discharge adhere to these chlorine atoms,
Ions or radicals easily react with moisture to form an acidic aqueous solution, that is, hydrochloric acid, and the dielectric film made of oxide reacts violently with hydrochloric acid and is eroded.

For this reason, the dielectric film 2 on the side wall 6 exposed to hydrochloric acid is dissolved in hydrochloric acid as shown in FIG. As shown in the figure, there has been a problem that the material is changed to another material 9 different from a dielectric material and loses its function as a capacitive insulating film, and short-circuiting of a capacitive element and an increase in leakage current occur frequently. In addition, the adsorption of moisture always occurs during operations such as exposing the substrate to the atmosphere and washing with water in the manufacturing process of the semiconductor device, and cannot be avoided.

[0007] Such inconvenience is recognized even when bromine or iodine is used as an etching gas.

The present invention has been made to solve the above-mentioned conventional problems, and can reduce the amount of chlorine, bromine or iodine remaining on a side wall portion of a dielectric film or a portion exposed by etching.
Accordingly, it is an object of the present invention to provide a method of manufacturing a semiconductor device capable of suppressing occurrence of erosion of a dielectric film and short-circuit of a capacitor.

[0009]

To achieve the above object, the present invention provides an insulating film, a platinum film for a lower electrode, a dielectric film, and a platinum film for an upper electrode on a substrate on which circuit elements, wirings and the like are formed. And selectively dry-etching the platinum film for the upper electrode and the dielectric film using an etching gas containing at least one of chlorine, bromine and iodine, and plasma generated by discharging the gas containing fluorine. Is irradiated.

Further, the substrate is heated after dry etching the platinum film for the upper electrode and the dielectric film.

Therefore, according to the present invention, after dry etching of the platinum film for the upper electrode and the dielectric film, a plasma generated by discharging a gas containing fluorine which does not react with moisture is irradiated to irradiate the side wall and the like. Replacing at least one of chlorine, bromine and iodine remaining in
Alternatively, since at least one of chlorine, bromine and iodine is desorbed by heating, erosion and deterioration of the dielectric film on the side wall can be suppressed, and as a result, a short circuit of the capacitive element and an increase in leakage current can be eliminated. it can.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG.

FIGS. 1A to 1C are views showing a process of forming a capacitor in a method of manufacturing a semiconductor device according to a first embodiment of the present invention.

First, as shown in FIG. 1A, the platinum film 3 for the upper electrode and the dielectric film 2 are dry-etched with an etching gas containing chlorine. At this time, chlorine atoms and ions generated by the decomposition of the etching gas by the discharge are formed on the side walls 6 of the upper electrode platinum film 3 and the dielectric film 2 and the surface 7 of the lower electrode platinum film 1 exposed by the etching. Or, radicals and the like adhere in large quantities.

Next, the substrate 4 on which a large amount of chlorine atoms, ions, radicals, etc. adhered by the dry etching.
Is irradiated with plasma generated by discharging fluorine or a gas containing the same, and the attached chlorine atoms and the like are replaced by fluorine atoms.

In this case, since chlorine is not in a state of being strongly bonded to the platinum or the dielectric of the side wall portion 6, it can be easily removed by irradiating active fluorine plasma. That is, when the plasma generated by discharging the gas containing fluorine after the platinum film 3 for the upper electrode and the dielectric film 2 are dry-etched is irradiated, chlorine is easily replaced by fluorine as shown in FIG. Then, as shown in FIG. 1C, the surfaces of the side wall 6 and the platinum film 1 for the lower electrode are covered with fluorine which does not easily react with moisture.

Then, the platinum film 1 for the lower electrode is selectively dry-etched to form electrodes of the capacitor in a predetermined pattern.

Next, a second embodiment of the present invention will be described.
This will be described with reference to FIG.

FIGS. 2A and 2B show a process of removing chlorine atoms and the like attached to the side wall 6 by heat treatment after dry etching as a second embodiment of the present invention.

As shown in FIG. 2A, the platinum film 3 for the upper electrode and the dielectric film 2 are dry-etched in the same manner as in the first embodiment, and then the side wall 6 and the surface of the platinum film 1 for the lower electrode are formed. As shown in FIG. 2 (b), the substrate 4 having a large amount of chlorine atoms, ions or radicals attached to the substrate 7 is subjected to a heat treatment to remove the attached chlorine atoms and the like. In this heat treatment, the chlorine is not strongly bonded to the platinum or the dielectric of the side wall portion 6 as described in the first embodiment, so that the substrate is easily desorbed by applying heat energy to the substrate 4.

Then, the platinum film 1 for the lower electrode is selectively dry-etched to form electrodes of the capacitor in a predetermined pattern.

In this heat treatment, as described in the first embodiment, since chlorine is not strongly bonded to platinum or the dielectric on the side wall portion 6, it is easily desorbed by applying heat energy to the substrate 4. I do.

FIG. 3 shows a change in the concentration of chlorine remaining on the substrate 4 of the semiconductor device obtained in the first and second embodiments. It should be noted that the values shown in FIG.
r, measured by irradiating fluorine plasma obtained by discharging under the condition of a load of RF power of 100 W for 30 seconds. In the second embodiment, the substrate is held in the same nitrogen atmosphere as the atmospheric pressure, It was measured by heating at a temperature of 180 ° C. for 60 seconds. In this figure, the ordinate represents the residual chlorine concentration, which is based on the residual chlorine concentration immediately after dry etching with an etching gas containing chlorine. The horizontal axis represents each processing in the first embodiment and the second embodiment.

As is apparent from FIG. 3, by irradiating a plasma generated by discharging a gas containing fluorine,
It can be seen that the residual chlorine concentration has been reduced to about 1/3.

Further, it can be seen that the residual chlorine concentration is similarly reduced to about 1/3 by heating the substrate 4, and the same effect as after the fluorine plasma irradiation shown in the first embodiment is obtained.

As described above, according to the above-described embodiment, an acidic corrosive aqueous solution is not formed even when moisture is adsorbed on the substrate, so that the dielectric film on the side wall is eroded or deteriorated. Therefore, it is possible to prevent a short circuit of the capacitor and an increase in leakage current.

Although chlorine is used as an etching gas in the above embodiment, an etching gas containing bromine or iodine or an etching gas containing a mixture of two or more of chlorine, bromine and iodine is used instead of chlorine. However, an effect equivalent to that of the above-described embodiment can be obtained.

Although nitrogen is used as the heating atmosphere in the second embodiment, the same effect can be obtained even when another inert gas is used or even in a vacuum. Further, the heating temperature is set to 180 ° C. However, the same effect can be obtained as long as the temperature is 150 ° C. or more and within a range that does not substantially change the characteristics of the semiconductor device.

[0029]

According to the present invention, an insulating film, a platinum film for a lower electrode, a dielectric film and a platinum film for an upper electrode are formed on a substrate on which circuit elements, wirings, etc. are formed. The film is selectively dry-etched using an etching gas containing at least one of chlorine, bromine and iodine, and then irradiated with plasma generated by discharging a gas containing fluorine. Since the substrate is heated after the dry etching, the erosion and deterioration of the side wall of the capacitive insulating film after the dry etching can be suppressed, and the short circuit of the capacitive element and the increase in leakage current can be eliminated. Things.

[Brief description of the drawings]

FIGS. 1A to 1C are process diagrams of forming a capacitive element in a method for manufacturing a semiconductor device according to a first embodiment of the present invention;

FIGS. 2A and 2B are process diagrams of forming a capacitive element in a method of manufacturing a semiconductor device according to a second embodiment; FIGS.

FIG. 3 is a characteristic diagram comparing the amounts of residual chlorine on a substrate in the first and second embodiments of the present invention and a conventional example.

FIGS. 4A and 4B are process diagrams of forming a capacitive element in a conventional method of manufacturing a semiconductor device; FIGS.
Is a cross-sectional view for explaining a problem in a conventional method of manufacturing a semiconductor device.

[Explanation of symbols]

 1 Platinum film for lower electrode 2 Dielectric film 3 Platinum film for upper electrode 4 Substrate

Claims (3)

[Claims] An insulating film, a platinum film for a lower electrode, a dielectric film, and a platinum film for an upper electrode are formed on a substrate on which circuit elements, wirings, and the like are formed, and the platinum film for the upper electrode and the dielectric film are formed. Is selectively dry-etched using an etching gas containing at least one of chlorine, bromine and iodine, and then irradiated with plasma which is generated by discharging fluorine which is less likely to react with moisture or a gas containing the same. Manufacturing method of a semiconductor device. 2. A surface obtained by irradiating plasma obtained by discharging fluorine or a gas containing the same, and irradiating side walls of the platinum film for the upper electrode and the dielectric film, and the surface of the platinum film for the lower electrode exposed by etching. 2. The method according to claim 1, wherein a decomposition product of the etching gas attached to the substrate is replaced with fluorine. 3. An insulating film, a platinum film for a lower electrode, a dielectric film and a platinum film for an upper electrode are formed on a substrate on which circuit elements, wirings and the like are formed, and the platinum film for the upper electrode and the dielectric film are formed. Selectively dry-etching the substrate with an etching gas containing at least one of chlorine, bromine and iodine, and then heating the substrate.