JP2000004010A - Manufacture of capacitor elements - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing capacitor elements, whereby an etching space without sidewall residues is realized to manufacture capacitor elements superior in reliability at high yield in dry etching of a capacitive insulation film and electrode material for forming the capacitor elements, with a capacitive insulation film using a high dielectric or ferroelectric. SOLUTION: Capacitor element electrodes or capacitive insulation film 2 and mask 3 are formed on a support substrate 1, the capacitor element electrodes or the capacitive insulation film 2 is dry-etched and are cleaned to remove reaction products deposited to the sidewalls of the mask 3 after etching without exposing to the open air, and the mask 3 is removed. The atmosphere for the cleaning is an inert gas such as H, Ar, He, etc., and the soln. for the cleaning is pref. a soln. contg. at least one selected from among water, hydrochloric acid, nitric acid, fluoric acid and org. solvents.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electric capacitor using a dielectric or ferroelectric having a high dielectric constant as a capacitor insulating film.

[0002]

2. Description of the Related Art In recent years, the speed of microcomputers and the like has been increased,
As the trend toward lower power consumption is promoted, consumer electronic devices are becoming more sophisticated, and semiconductor devices used are also being miniaturized. As a result, unnecessary radiation, which is electromagnetic wave noise generated from electronic equipment, has become a major problem. As a measure to reduce this unnecessary radiation, a dielectric having a high dielectric constant (hereinafter simply referred to as a high dielectric) is used as a capacitive insulating film. Attention has been paid to a technology for incorporating a large-capacity capacitive element in a semiconductor integrated circuit device or the like. Also, with the high integration of dynamic RAMs (DRAMs), techniques for using a high dielectric as a capacitor insulating film instead of the conventional silicon oxide or nitride have been widely studied. Furthermore, a non-conventional low-operating voltage and non-volatile
Research and development on ferroelectric films having spontaneous polarization characteristics have been actively conducted with the aim of commercializing M.

Hereinafter, a conventional method for manufacturing a semiconductor device will be described with reference to the drawings. 6 (a) to 6 (c)
Is a process cross-sectional view showing a conventional method of manufacturing a capacitive element,
1 is a supporting substrate of a semiconductor or the like, 2 is a capacitor element electrode or a capacitive insulating film made of a high dielectric or ferroelectric, 3 is a mask made of a photo-curable resin, etc., 4 is a side wall of the mask 3 as a result of dry etching. It is a reaction product attached to. First, a capacitor element electrode or a capacitor insulating film 2 is formed on a supporting substrate 1 by a sputtering method or an organic metal deposition method, and a mask 3 is formed for processing into a desired shape. To
Next, as shown in FIG. 6B, the electrode for the capacitor or the capacitor insulating film 2 is dry-etched. Finally, the mask is removed as shown in FIG.

[0004]

However, in the above-mentioned conventional manufacturing method, the reaction product 4 adhered to the side wall of the mask 3 when the electrode for the capacitive element or the capacitive insulating film 2 is dry-etched remains after the mask is removed. For this reason, there has been a problem that a coverage failure of a thin film formed on the capacitor element after the dry etching occurs and normal characteristics cannot be obtained.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method of manufacturing a capacitive element capable of obtaining normal characteristics of a capacitive element because there is no reaction product attached to a mask side wall. I do.

[0006]

In order to achieve the above object, a first method of manufacturing a capacitor according to the present invention is directed to a method of manufacturing a capacitor using a dielectric or ferroelectric having a high dielectric constant as a capacitor insulating film. In the formation, a step of patterning a mask material, a step of dry-etching an electrode material or a dielectric material constituting the capacitive element, a step of performing cleaning without exposing to air after the dry etching, Removing step. With this configuration, an etched shape in which a reaction product does not adhere even after dry etching of the capacitor electrode or the capacitor insulating film can be realized, and thus normal characteristics of the capacitor can be obtained.

In the above, the dielectric having a high dielectric constant includes strontium titanate (SrTiO ₃ ), barium strontium titanate (Ba _x Sr _{1 -x} TiO ₃ , where 0 <x <1), tantalum oxide ( Ta ₂ O ₅ ). Ferroelectrics are lead zirconium titanate (P
bZr _1-x Ti _x O ₃ , where 0 <x <1), and bismuth strontium tantalate (SrBi ₂ Ta ₂ O ₉ ).

Next, a second method of manufacturing a capacitive element according to the present invention provides a method of forming a capacitive element using a dielectric or ferroelectric having a high dielectric constant as a capacitive insulating film by using a mask material of 5 °.
Patterning so as to have a taper angle of not less than 80 °, a step of dry-etching an electrode material or a dielectric material constituting the capacitive element, and a step of removing the mask material. . With this configuration, reaction products adhering to the mask side wall during dry etching of the capacitor element electrode or the capacitor insulating film can be physically removed by ion bombardment during dry etching, realizing an etched shape without reaction product adhesion. Therefore, normal characteristics of the capacitor can be obtained.

Next, a third method of manufacturing a capacitive element according to the present invention includes a step of patterning a mask material in forming a capacitive element using a dielectric or ferroelectric having a high dielectric constant as a capacitive insulating film; A step of dry-etching an electrode material or a dielectric material constituting the capacitor at a substrate temperature of 100 ° C. or more and 400 ° C. or less; and a step of removing the mask material. With this configuration, the reaction product at the time of dry etching of the capacitor element electrode or the capacitor insulating film can be exhausted in a highly volatile state,
Since an etched shape without the attachment of reaction products can be realized, normal characteristics of the capacitor can be obtained.

In the first to third capacitive element manufacturing methods of the present invention, the electrode material constituting the capacitive element is platinum, palladium, ruthenium, ruthenium oxide, iridium, iridium oxide, titanium, titanium oxide and nitride. It is preferable that the material contains at least one selected from titanium.

In the first to third methods of manufacturing a capacitor according to the present invention, the mask material is at least one selected from the group consisting of photoresist, silicon oxide, titanium, titanium oxide, titanium nitride, tantalum and tungsten. Preferably, it is a material containing.

In the first method of manufacturing a capacitive element according to the present invention, it is preferable that the cleaning atmosphere is at least one inert gas atmosphere selected from nitrogen, argon and helium. This prevents the reaction product from becoming a stable substance that is difficult to remove due to oxidation.

[0013] In the first method of manufacturing a capacitive element of the present invention, the solution used for cleaning may be a solution containing at least one selected from water, hydrochloric acid, nitric acid, hydrofluoric acid and an organic solvent. preferable. Thereby, the reaction product can be removed chemically.

[0014]

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIGS. 1A to 1D are process sectional views of a method of manufacturing a capacitor according to a first embodiment of the present invention. First, as shown in FIG. 1A, a capacitor element electrode or a capacitor insulating film 2 is formed on a supporting substrate 1 such as a compound semiconductor such as Si or GaAs or a glass substrate by a sputtering method or an organic metal deposition method. Thus, a mask 3 for processing into a desired shape was formed. Next, as shown in FIG. 1B, the electrode for the capacitor element or the capacitor insulating film 2 was dry-etched. At this time, the reaction product 4 adhered to the side wall of the mask 3. Next, as shown in FIG. 1C, the etched support substrate 1 is washed in a nitrogen atmosphere without being exposed to the air.
The reaction product 4 attached to the side wall of the mask 3 was removed. Finally, as shown in FIG. 1D, the mask 3 was removed.

As described above, according to the above-described embodiment, by cleaning the electrode for the capacitor element or the capacitor insulating film 2 without being exposed to oxygen after the dry etching, the reaction product 4 is oxidized and is difficult to remove. The reaction product 4 adhering to the side wall of the mask 3 could be easily removed without becoming.

For example, when platinum is used as the electrode for the capacitive element, the gas used in the dry etching mainly contains chlorine, so that the reaction product is platinum dichloride or platinum tetrachloride. Platinum dichloride dissolves in hydrochloric acid. Also, 4
Platinum chloride dissolves in water, ethanol or acetone. As described above, if a mixture of hydrochloric acid and water is used as the cleaning agent, the reaction product 4 attached to the side wall of the mask 3 can be completely removed. When platinum dichloride or platinum tetrachloride is oxidized, platinum chloride oxide is formed. Since it is chemically very stable and difficult to remove, it is essential to clean it without exposing it to the atmosphere.

Further, for example, SrBi ₂
When Ta ₂ O ₉ is used, the gas used in the dry etching mainly contains chlorine or fluorine, so that the reaction product 4 is BiCl _x and SrCl _x , TaCl _x , or B
iF _x, SrF _x , and TaF _x . These dissolve in a mixture of hydrofluoric acid and nitric acid. As described above, if a mixed solution of hydrofluoric acid and nitric acid is used, the reaction product 4 attached to the side wall of the mask 3 can be completely removed.

The thickness of the capacitor electrode or capacitor insulating film 2 obtained as described above was 0.2 to 0.4 μm. Note that, in this embodiment, as the capacitor element electrode,
Although platinum was used, a similar effect can be obtained with a material containing at least palladium, ruthenium, ruthenium oxide, iridium, iridium oxide, titanium, titanium oxide, or titanium nitride.

In this embodiment, a mixture of hydrochloric acid and water and a mixture of hydrofluoric acid and nitric acid are used as the cleaning agent.
Various selections can be made according to the electrode material for the capacitor element or the capacitor insulating film. For example, a material containing at least 80 ° C. water or an organic solvent can be used.

In this embodiment, nitrogen is used as the atmosphere during cleaning. However, an equivalent effect can be obtained with an inert gas such as argon or helium.

(Embodiment 2) Next, a second embodiment of the present invention will be described with reference to the drawings. FIG.
(A)-(c) is process sectional drawing of the manufacturing method of the capacitive element in the 2nd Embodiment of this invention. First, FIG.
As shown in FIG. 5, a capacitor element electrode or a capacitor insulating film 2 is formed on a support substrate 1 in the same manner as in the first embodiment, and then a mask 3 for processing into a desired shape is formed at 75 °.
A photoresist having a taper angle θ was formed.
Next, as shown in FIG. 2B, the electrode for the capacitor element or the capacitor insulating film 2 was dry-etched. At this time, the reaction product 4 attached to the side wall of the mask 3 was sputter-etched by the collision of the ions 5 during the dry etching. Finally, as shown in FIG. 2C, the mask 3 was removed.

As described above, according to the above embodiment, 75
Because of the mask shape having a taper angle of 0 °, the mask side wall is always exposed to ion bombardment during dry etching, and as a result, the reaction product 4 attached to the side wall is sputter-etched, An etching shape without a reaction generating portion (hereinafter, referred to as a residue) remaining after adhering to the substrate was realized.

FIG. 3 shows the relationship between the taper angle θ when a photoresist is used as the mask 3 and the ratio of the reaction product 4 adhering to the side wall of the mask 3 (side wall adhering rate). It was confirmed that a shape without residue can be realized if the taper angle θ is 80 ° or less. Also,
If the taper angle θ is less than 5 °, both ends of the mask will not function as a mask. Therefore, the taper angle θ is preferably 5 ° or more and 80 ° or less.

According to the present embodiment, a photoresist is used as the material of the mask 3, but a similar effect can be obtained by using a material containing at least silicon oxide, tantalum, titanium, titanium oxide, titanium nitride or tungsten. .

(Embodiment 3) Next, a third embodiment of the present invention will be described with reference to the drawings. FIG.
(A)-(c) is process sectional drawing of the manufacturing method of the capacitive element in the 3rd Embodiment of this invention. First, FIG.
As shown in FIG. 5, an electrode for a capacitor or a capacitor insulating film 2 was formed on a support substrate 1 in the same manner as in the first embodiment, and then a mask 3 for processing into a desired shape was formed.
Next, as shown in FIG. 4B, the electrode for the capacitor element or the capacitor insulating film 2 was dry-etched while the temperature of the supporting substrate 1 (hereinafter, referred to as substrate temperature) was kept at 120 ° C.
At this time, since the substrate temperature was maintained at 120 ° C., the reaction product 4 was rich in volatility, and as a result, was exhausted without adhering to the side wall of the mask 3. Finally, as shown in FIG. 4C, the mask 3 was removed.

As described above, according to the above embodiment, since dry etching is performed while the substrate temperature is kept at 120 ° C., even a material having low volatility at room temperature can be easily volatilized. As a result, the reaction product 4 becomes the mask 3
The gas is exhausted without adhering to the side wall of the substrate, and an etched shape having no residue can be realized.

FIG. 5 shows the relationship between the substrate temperature and the rate of occurrence of the side wall adhesion rate, and it was confirmed that if the substrate temperature was 100 ° C. or higher, a shape with no residue could be realized. On the other hand, when the substrate temperature exceeds 400 ° C., the characteristics of the capacitor are likely to deteriorate. Therefore, the substrate temperature is 100 ° C. or more and 400 ° C.
The following is preferred.

[0029]

As described above, according to the present invention, cleaning is performed without being exposed to air immediately after etching, or a taper angle of 5 ° or more and 80 ° or less is applied to a mask material.
Alternatively, it is possible to provide a method for manufacturing a capacitive element having excellent reliability that realizes a highly accurate etched shape that does not remain on a mask side wall by performing dry etching while maintaining a substrate temperature at 100 ° C. or higher and 400 ° C. or lower. It becomes possible.

[Brief description of the drawings]

FIGS. 1A to 1D are process diagrams in a method for manufacturing a capacitive element according to a first embodiment of the present invention.

FIGS. 2A to 2C are process diagrams in a method for manufacturing a capacitor according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a taper angle of a photoresist and a rate of occurrence of side wall adhesion according to a second embodiment of the present invention.

FIGS. 4A to 4C are process diagrams in a method for manufacturing a capacitor according to a third embodiment of the present invention.

FIG. 5 is a diagram illustrating a relationship between a substrate temperature and a side wall adhesion occurrence rate according to a third embodiment of the present invention.

6 (a) to 6 (c) are process diagrams in a conventional method for manufacturing a capacitive element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support substrate 2 Electrode or capacitive insulating film for capacitive elements 3 Mask 4 Reaction product

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Claims (7)

[Claims] In forming a capacitor using a dielectric or a ferroelectric having a high dielectric constant as a capacitor insulating film, a step of patterning a mask material and a step of drying an electrode material or a dielectric material forming the capacitor are performed. A method for manufacturing a capacitive element, comprising: a step of performing etching; a step of performing cleaning without exposing to air after the dry etching; and a step of removing the mask material. 2. A step of patterning a mask material so as to have a taper angle of not less than 5 ° and not more than 80 ° in forming a capacitive element using a dielectric or a ferroelectric having a high dielectric constant as a capacitive insulating film; A method for manufacturing a capacitive element, comprising: a step of dry-etching an electrode material or a dielectric material forming a capacitive element; and a step of removing the mask material. 3. A step of patterning a mask material in forming a capacitive element using a dielectric or ferroelectric having a high dielectric constant as a capacitive insulating film, and using an electrode material or a dielectric material constituting the capacitive element by 100%. A method for manufacturing a capacitive element, comprising: a step of performing dry etching at a substrate temperature of not less than 400C and a temperature of not more than 400C; and a step of removing the mask material. 4. An electrode material constituting a capacitive element is platinum,
The method for manufacturing a capacitive element according to any one of claims 1 to 3, wherein the material includes at least one selected from palladium, ruthenium, ruthenium oxide, iridium, iridium oxide, titanium, titanium oxide, and titanium nitride. 5. The capacitive element according to claim 1, wherein the mask material is a material containing at least one selected from photoresist, silicon oxide, titanium, titanium oxide, titanium nitride, tantalum and tungsten. Manufacturing method. 6. The method according to claim 1, wherein the atmosphere in which the cleaning is performed is at least one inert gas atmosphere selected from nitrogen, argon, and helium. 7. The solution used for washing is water, hydrochloric acid, nitric acid,
The method according to claim 1, wherein the solution is a solution containing at least one selected from hydrofluoric acid and an organic solvent.