JP2023109710A - Microprocessing treatment agent and microprocessing treatment method - Google Patents

Abstract

To provide: a microprocessing treatment agent and a microprocessing treatment method which make it possible to satisfactorily perform, in a laminated film at least including a silicon oxide film and a silicon nitride film, selective microprocessing of the silicon nitride film while inhibiting microprocessing of the silicon oxide film.SOLUTION: The microprocessing treatment agent at least includes a compound represented by a prescribed chemical formula, an inorganic phosphoric acid, a hexafluorosilicic acid compound, and water.SELECTED DRAWING: None

Description

The present invention relates to a microfabrication treatment agent and a microfabrication treatment method used for microfabrication, including etching and cleaning, in the manufacture of semiconductor devices, liquid crystal display devices, microelectromechanical systems (MEMS) devices, and the like. More specifically, the present invention relates to a microfabrication agent and a microfabrication method used for microfabrication of a laminated film containing at least a silicon oxide film and a silicon nitride film.

2. Description of the Related Art In the manufacturing process of semiconductor devices, there is a step of patterning a silicon oxide film, a silicon nitride film, a silicon alloy, a polysilicon film, a metal film, etc. formed on a wafer surface into a desired shape and etching the film. The etching method is roughly classified into a dry etching method and a wet etching method.

Dry etching methods, also called anisotropic etching, use reactive gases to remove the target film on the wafer. Since the dry etching method proceeds only in the direction perpendicular to the film surface of the target film, fine processing is possible. On the other hand, the dry etching apparatus is expensive and basically processes wafers one by one in a batch process with the inside of the reaction apparatus kept in a vacuum state, which has the disadvantages of high manufacturing cost and low throughput.

The wet etching method is also called isotropic etching, and removes a target film using a liquid chemical solution. Since the wet etching method can process a large number of wafers at once, it has the advantage of being able to reduce costs and improve throughput. On the other hand, the wet etching method has a demerit that etching extends to the lower portion of the pattern, resulting in a processing dimension larger than the size of the formed pattern.

Semiconductor devices to which the wet etching method is applied in the manufacturing process include, for example, 3D-NAND type nonvolatile memories. Conventional NAND-type nonvolatile memories are planar and have increased in capacity through miniaturization. Therefore, the 3D-NAND type nonvolatile memory increases the capacity without reducing the size of the memory cells by stacking the memory cells in the vertical direction.

A memory cell portion of a 3D-NAND nonvolatile memory is formed by alternately stacking silicon nitride films and silicon oxide films. A fine hole is formed in the alternately laminated silicon nitride film and silicon oxide film by dry etching. This hole has a high aspect ratio with an etching width of several hundred nanometers and an etching depth of several micrometers in a cross-sectional view. A wet etching method is applied to etch only the silicon nitride film when forming the recess structure in the silicon nitride film in the hole.

Wet etching is also used in the STI (Shallow Trench Isolation) process, which forms a buried insulating film (silicon oxide film) to electrically insulate (separate) between elements in transistors of semiconductor elements such as logic and memory. Law applies. Specifically, in the STI process, after planarizing the buried insulating film by CMP (Chemical Mechanical Polishing), the wet etching method is used in the process of selectively removing the silicon nitride film while leaving the silicon oxide film. Applies.

For the formation of the recess structure in the 3D-NAND nonvolatile memory and the element isolation using the STI process in the transistor, the etching of the silicon oxide film is suppressed as much as possible, and the silicon nitride film is formed satisfactorily. Selective etching is required.

Here, as a wet etching method for selectively etching the silicon nitride film, there is a method using high-temperature phosphoric acid as an etchant. However, with this wet etching method, the silicon oxide film is somewhat etched, and as a result, it may be difficult to microfabricate into a desired shape.

To address such problems, for example, Patent Document 1 discloses an etching solution containing a phosphoric acid solution, a silicon-containing compound (silica or polysiloxane), and a solvent. Patent Document 2 discloses an etching composition comprising a compound and/or mixture of silicon and fluorine having an F/Si atomic ratio of less than 6.0 and phosphoric acid. However, the etching solution of Patent Document 1 and the etching composition of Patent Document 2 have a problem that silicon-derived precipitates are generated on the silicon oxide film.

Patent Document 3 discloses a silicon nitride etching composition comprising a phosphorus compound, a boron compound and/or their fluorides, and water. According to this Patent Document 3, the etching composition can suppress damage to a silicon oxide film and suppress generation of precipitates. However, the etching composition of Patent Document 3 cannot sufficiently suppress damage to a silicon oxide film, and has a problem that sufficient selective etching characteristics cannot be obtained.

Japanese Patent Application Laid-Open No. 2000-58500 Japanese Patent Application Laid-Open No. 2007-12640 Japanese Patent Application Laid-Open No. 2009-21538

The present invention has been made in view of the above problems, and an object thereof is to provide a laminated film containing at least a silicon oxide film and a silicon nitride film, while suppressing microfabrication of the silicon oxide film. It is an object of the present invention to provide a fine processing agent and a fine processing method, which can satisfactorily carry out effective fine processing.

In order to solve the above problems, the microfabrication agent of the present invention is a microfabrication agent used for microfabrication of a laminated film containing at least a silicon oxide film and a silicon nitride film, and is represented by the following chemical formula (1): The silicon nitride film is selectively microfabricated with respect to the silicon oxide film, including at least the represented compound, inorganic phosphoric acid, a hexafluorosilicic acid compound, and water.

（Ｘは、水素原子、ケイ素原子又は前記化学式（２）～（４）で表される官能基の何れかを表す。前記化学式（２）～（４）に於けるＲ^１、Ｒ^２及びＲ^３は、それぞれ独立して、水素原子、フッ素原子、塩素原子、臭素原子、ヨウ素原子、炭素数が１～２０のアルキル基、炭素数が２～２０のアルケニル基、炭素数が２～２０のアルキニル基、炭素数が１～２０のヒドロキシアルキル基、炭素数が１～２０のアルコキシ基、炭素数が１～２０のアミノアルコキシ基、ホスフェート基、サルフェート基、ニトリル基、カルボキシル基又はアセトキシ基の何れかを表す。ｎは１～４の整数を表す。）

(X represents either a hydrogen atom, a silicon atom, or a functional group represented by the chemical formulas (2) to (4). R ¹ , R ² and R in the chemical formulas (2) to (4) ³ each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group, a hydroxyalkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aminoalkoxy group having 1 to 20 carbon atoms, a phosphate group, a sulfate group, a nitrile group, a carboxyl group or an acetoxy group; represents any. n represents an integer of 1 to 4.)

According to the above configuration, by containing the hexafluorosilicic acid compound, it is possible to suppress microfabrication of the silicon oxide film and improve selective microfabrication of the silicon nitride film. In addition, for example, the etching rate of silicon nitride films can be improved compared to conventional microfabrication agents containing silica or polysiloxane. Furthermore, by containing the compound represented by the chemical formula (1), it is possible to reduce or prevent the deposition (generation) of a silicon compound derived from the hexafluorosilicic acid compound (for example, silicon oxide). This can reduce or prevent the silicon compound from adhering to the surface of the silicon oxide film and causing the silicon oxide film to grow.

In the above configuration, the content of the compound represented by the chemical formula (1) is preferably 0.001% by mass or more and 0.1% by mass or less with respect to the total mass of the fine processing agent. . By setting the content of the compound represented by the chemical formula (1) to 0.001% by mass or more, the deposition (generation) of the silicon compound derived from the hexafluorosilicate compound is further reduced or prevented, and the silicon oxide film is formed. can reduce or prevent the silicon compound from adhering to the As a result, it is possible to further reduce or prevent the growth of the silicon oxide film. On the other hand, by setting the content of the compound represented by the chemical formula (1) to 0.1% by mass or less, the etching rate of the silicon oxide film can be kept well suppressed.

Moreover, in the above configuration, the content of the inorganic phosphoric acid is preferably 50% by mass or more and 90% by mass or less with respect to the total mass of the fine processing agent. By setting the content of inorganic phosphoric acid within this numerical range, the etching rate for the silicon nitride film can be favorably maintained.

Furthermore, in the above configuration, the content of the hexafluorosilicic acid compound is preferably 0.01% by mass or more and 0.3% by mass or less with respect to the total mass of the fine processing agent. By setting the content of the hexafluorosilicate compound to 0.01% by mass or more, the effect of suppressing the etching rate of the silicon oxide film can be maintained, thereby improving the etching rate of the silicon nitride film. can. On the other hand, by setting the content of the hexafluorosilicic acid compound to 0.3% by mass or less, the suppression of the etching rate of the silicon oxide film can be maintained satisfactorily.

In the above configuration, the fine processing agent preferably has an etch rate of 1 nm/min or more at 180° C. or less with respect to the silicon nitride film. As a result, it is possible to prevent the microfabrication process from taking a long time, and to prevent a decrease in processing (production) efficiency.

In the above structure, the silicon oxide film includes a natural oxide film, a chemical oxide film, a silicon thermal oxide film, a non-doped silicate glass film, a phosphorus doped silicate glass film, a boron doped silicate glass film, a phosphorous boron doped silicate glass film, Any one of a TEOS film, a fluorine-containing silicon oxide film, a carbon-containing silicon oxide film, a nitrogen-containing silicon oxide film, an SOG film, or an SOD film may be used.

Further, in the above configuration, the silicon nitride film may be any of a silicon nitride film, an oxygen-containing silicon nitride film, or a carbon-containing silicon nitride film.

In order to solve the above problems, the microfabrication method of the present invention is a microfabrication method for a laminated film containing at least a silicon oxide film and a silicon nitride film, wherein the compound represented by the following chemical formula (1) and a microfabrication agent containing at least inorganic phosphoric acid, a hexafluorosilicic acid compound, and water to selectively microfabricate the silicon nitride film with respect to the silicon oxide film. .

（Ｘは、水素原子、ケイ素原子又は前記化学式（２）～（４）で表される官能基の何れかを表す。前記化学式（２）～（４）に於けるＲ^１、Ｒ^２及びＲ^３は、それぞれ独立して、水素原子、フッ素原子、塩素原子、臭素原子、ヨウ素原子、炭素数が１～２０のアルキル基、炭素数が２～２０のアルケニル基、炭素数が２～２０のアルキニル基、炭素数が１～２０のヒドロキシアルキル基、炭素数が１～２０のアルコキシ基、炭素数が１～２０のアミノアルコキシ基、ホスフェート基、サルフェート基、ニトリル基、カルボキシル基又はアセトキシ基の何れかを表す。ｎは１～４の整数を表す。）

(X represents either a hydrogen atom, a silicon atom, or a functional group represented by the chemical formulas (2) to (4). R ¹ , R ² and R in the chemical formulas (2) to (4) ³ each independently represents a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group, a hydroxyalkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aminoalkoxy group having 1 to 20 carbon atoms, a phosphate group, a sulfate group, a nitrile group, a carboxyl group or an acetoxy group; represents any. n represents an integer of 1 to 4.)

According to the above configuration, the silicon nitride film is selectively fine-processed while suppressing the fine-processing of the silicon oxide film by using the above-described fine-processing agent for the laminated film including at least the silicon oxide film and the silicon nitride film. can be performed well. In addition, since the deposition (generation) of a silicon compound (for example, silicon oxide, etc.) derived from the hexafluorosilicate compound is reduced or prevented, the silicon compound adheres to the silicon oxide film and the silicon oxide film grows. can also be reduced or prevented. As a result, with the above configuration, for example, in semiconductor manufacturing processes such as the formation of recess structures in 3D-NAND nonvolatile memories and the formation of element isolation using the STI process in transistors, silicon oxidation The silicon nitride film can be selectively microfabricated while suppressing microfabrication of the film, and the yield can be improved.

In the above configuration, the content of the compound represented by the chemical formula (1) is preferably 0.001% by mass or more and 0.1% by mass or less with respect to the total mass of the fine processing agent. . By setting the content of the compound represented by the chemical formula (1) to 0.001% by mass or more, the deposition (generation) of the silicon compound derived from the hexafluorosilicate compound is further reduced or prevented, and the silicon oxide film is formed. can reduce or prevent the silicon compound from adhering to the As a result, it is possible to further reduce or prevent the growth of the silicon oxide film. On the other hand, by setting the content of the compound represented by the chemical formula (1) to 0.1% by mass or less, the etching rate of the silicon oxide film can be kept well suppressed.

Moreover, in the above configuration, the content of the inorganic phosphoric acid is preferably 50% by mass or more and 90% by mass or less with respect to the total mass of the fine processing agent. By setting the content of inorganic phosphoric acid within this numerical range, the etching rate for the silicon nitride film can be favorably maintained.

Furthermore, in the above configuration, the content of the hexafluorosilicic acid compound is preferably 0.01% by mass or more and 0.3% by mass or less with respect to the total mass of the fine processing agent. By setting the content of the hexafluorosilicate compound to 0.01% by mass or more, the effect of suppressing the etching rate of the silicon oxide film can be maintained, thereby improving the etching rate of the silicon nitride film. can. On the other hand, by setting the content of the hexafluorosilicic acid compound to 0.3% by mass or less, the suppression of the etching rate of the silicon oxide film can be maintained satisfactorily.

In the above configuration, the fine processing agent preferably has a temperature of 180° C. or less. As a result, evaporation of the fine processing agent can be suppressed, and a change in the composition of the fine processing agent can be prevented. In addition, it is possible to prevent difficulty in controlling the etch rate due to evaporation of the fine processing agent.

In the above structure, the silicon oxide film includes a natural oxide film, a chemical oxide film, a silicon thermal oxide film, a non-doped silicate glass film, a phosphorus doped silicate glass film, a boron doped silicate glass film, a phosphorous boron doped silicate glass film, Any one of a TEOS film, a fluorine-containing silicon oxide film, a carbon-containing silicon oxide film, a nitrogen-containing silicon oxide film, an SOG film, or an SOD film may be used.

Further, in the above configuration, the silicon nitride film may be any of a silicon nitride film, an oxygen-containing silicon nitride film, or a carbon-containing silicon nitride film.

ADVANTAGE OF THE INVENTION This invention has an effect as described below by the means demonstrated above.
That is, according to the present invention, in a laminated film containing at least a silicon oxide film and a silicon nitride film, selective microfabrication is performed on the silicon nitride film while preventing microfabrication of the silicon oxide film and film growth of the silicon oxide film. It is possible to provide a fine processing agent and a fine processing method that can be processed.

(fine processing agent)
A fine processing agent according to one embodiment of the present invention will be described below.
The fine processing agent according to the present embodiment contains at least a compound represented by the following chemical formula (1), inorganic phosphoric acid, a hexafluorosilicic acid compound, and water. The microfabrication agent of the present embodiment is suitable for selective microfabrication of a silicon nitride film with respect to a silicon oxide film in a laminated film containing at least a silicon oxide film and a silicon nitride film.

In this specification, the term "microfabrication" includes etching treatment for microfabrication of the surface of the laminated film, cleaning treatment of the surface of the laminated film, and the like. When the laminated film is etched, the fine processing agent of the present embodiment functions as an etchant. Further, when cleaning the laminated film, the fine processing agent of the present embodiment functions as a cleaning liquid.

By containing the compound represented by the chemical formula (1), the fine processing agent of the present embodiment prevents the precipitation (generation) of a silicon compound (for example, silicon oxide) derived from a hexafluorosilicic acid compound. can be reduced or prevented. As a result, it is possible to prevent the silicon compound from adhering to the silicon oxide film and to reduce or prevent the film growth of the silicon oxide film.

In chemical formula (1), X is a hydrogen atom, a silicon atom, or a functional group represented by any one of chemical formulas (2) to (4). R ¹ , R ² and R ³ in chemical formulas (2) to (4) each independently represent a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group, an alkenyl group, an alkynyl group, It represents any one of a hydroxyalkyl group, an alkoxy group, an aminoalkoxy group, a phosphate group, a sulfate group, a nitrile group, a carboxyl group and an acetoxy group. When X is a silicon atom, n=4, and when X is a hydrogen atom or a functional group represented by chemical formula (2), n=1, and X is represented by chemical formula (3). When X is a functional group represented by the chemical formula (4), n=3.

The alkyl groups for R ¹ , R ² and R ³ may each independently be linear or branched. The number of carbon atoms in the alkyl group is 1-20, preferably 1-8, more preferably 1-4. Specific examples of alkyl groups include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, and hexadecyl groups. group, eicosyl group, and the like. Among these alkyl groups, a methyl group, an ethyl group, a propyl group, a butyl group, and the like are preferable from the viewpoint of improving the solubility in water.

In this specification, when a range of carbon number is expressed, the range means to include all integer carbon numbers included in the range. Thus, for example, an "alkyl group having 1 to 3 carbon atoms" means all alkyl groups having 1, 2 and 3 carbon atoms, ie methyl, ethyl and propyl groups.

The alkenyl groups for R ¹ , R ² and R ³ may each independently be linear or branched. The number of carbon atoms in the alkenyl group is 2-20, preferably 2-8, more preferably 2-4. Specific examples of alkenyl groups include vinyl, allyl, 1-propenyl, 2-propenyl, 2-butenyl, 3-butenyl, 3-pentenyl, 4-pentenyl, and 1-hexenyl groups. , 5-hexenyl group, and 7-octenyl group. Among these alkenyl groups, vinyl group, 1-propenyl group, 2-propenyl group, 2-butenyl group, 3-butenyl group and the like are preferable from the viewpoint of improving solubility in water.

The alkynyl groups for R ¹ , R ² and R ³ may each independently be linear or branched. The alkynyl group has 2 to 20 carbon atoms, preferably 2 to 8 carbon atoms, more preferably 2 to 4 carbon atoms. Specific examples of alkynyl groups include ethynyl, 1-propynyl, 2-propynyl, 2-butynyl, 3-butynyl, 3-pentynyl, 4-pentynyl, 1-hexynyl, and 5 -hexynyl group and the like. Among these alkynyl groups, ethynyl group, 1-propynyl group, 2-propynyl group, 2-butynyl group, 3-butynyl group and the like are preferable from the viewpoint of improving solubility in water.

The hydroxyalkyl groups for R ¹ , R ² and R ³ may each independently be linear or branched. The hydroxyalkyl group has 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. Specific examples of hydroxyalkyl groups include hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, hydroxypentyl, hydroxyhexyl, hydroxyheptyl, hydroxyoctyl, hydroxynonyl, and hydroxydecyl groups. , hydroxyundecyl group, hydroxydodecyl group, hydroxytridecyl group, hydroxytetradecyl group, hydroxypentadecyl group, hydroxyhexadecyl group, hydroxyheptadecyl group, hydroxyoctadecyl group, hydroxynonadecyl group, hydroxyeicosyl group, etc. is mentioned. Among these hydroxyalkyl groups, a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a hydroxybutyl group, and the like are preferable from the viewpoint of improving the solubility in water.

The alkoxy groups in R ¹ , R ² and R ³ may each independently be linear or branched. The number of carbon atoms in the alkoxy group is 1-20, preferably 1-8, more preferably 1-4. Specific examples of alkoxy groups include methoxy, ethoxy, propyloxy, isopropyloxy, butyloxy, isobutyloxy, tert-butyloxy, pentyloxy, hexyloxy, heptyloxy, and octyloxy groups. group, 2-ethylhexyloxy group, nonyloxy group, decyloxy group, and lauryloxy group. Among these alkoxy groups, methoxy group, ethoxy group, propyloxy group, isopropyloxy group, butyloxy group, isobutyloxy group, tert-butyloxy group and the like are preferable from the viewpoint of improving solubility in water.

The aminoalkoxy groups for R ¹ , R ² and R ³ may be linear or branched. The aminoalkoxy group has 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms. Specific examples of the aminoalkoxy group include, for example, aminomethoxy group, aminoethoxy group, aminopropyloxy group, aminobutyloxy group, aminopentyloxy group, aminohexyloxy group, aminoheptyloxy group, aminooctyloxy group, amino nonyloxy group, aminodecyloxy group, aminolauryloxy group and the like. Among these aminoalkoxy groups, an aminomethoxy group, an aminoethoxy group, an aminopropyloxy group, an aminobutyloxy group, and the like are preferable from the viewpoint of improving the solubility in water.

Specific examples of sulfate groups for R ¹ , R ² and R ³ include -SO ₄ group, -OS(=O) ₂ OCH ₃ group, and -SO(=O) ₂ OCH ₂ CH ₃ and the like. Of these sulfate groups, the —SO ₄ group and the like are preferable from the viewpoint of improving the solubility in water.

The content of the compound represented by the chemical formula (1) is preferably in the range of 0.001% by mass or more and 0.1% by mass or less with respect to the total mass of the fine processing agent, and is 0.005% by mass or more. , 0.05% by mass or less is more preferable. By setting the content of the compound represented by the chemical formula (1) to 0.001% by mass or more, deposition (generation) of the silicon compound derived from the hexafluorosilicate compound and adhesion to the silicon oxide film can be reduced or can be prevented. As a result, it is possible to further reduce or prevent the growth of the silicon oxide film. On the other hand, by setting the content of the compound represented by the chemical formula (1) to 0.1% by mass or less, the etching rate of the silicon oxide film can be further suppressed.

In this embodiment, the inorganic phosphoric acid is contained in the fine processing agent to prevent the etching rate for the silicon nitride film from becoming small.

_{The inorganic} phosphoric _{acid is} not _{particularly limited .} O ₁₀ ), metaphosphoric acid (HPO ₃ ), hexametaphosphoric acid and the like. These inorganic phosphoric acids can be used alone or in combination of two or more. Among these inorganic phosphoric acids, phosphoric acid (orthophosphoric acid, H ₃ PO ₄ ) is preferable from the viewpoint of availability.

The content of inorganic phosphoric acid is preferably in the range of 50% by mass or more and 90% by mass or less, more preferably in the range of 55% by mass or more and 85% by mass or less with respect to the total mass of the fine processing agent. be. By setting the content of inorganic phosphoric acid within this numerical range, the etching rate of the silicon nitride film can be favorably maintained.

In the present embodiment, the hexafluorosilicic acid compound suppresses microfabrication of the silicon oxide film and makes it possible to improve selective microfabrication of the silicon nitride film. Hexafluorosilicic acid compounds can also improve the etch rate of silicon nitride films compared to conventional microfabrication treatments including, for example, silica or polysiloxane.

Here, the term "hexafluorosilicic acid compound" as used herein means a generic term for hexafluorosilicic acid and salts thereof (eg, ammonium salts, etc.). Specifically, the hexafluorosilicic acid compound of the present embodiment contains at least one of hexafluorosilicic acid (H ₂ SiF ₆ ) and ammonium hexafluorosilicate ((NH ₄ ) ₂ SiF ₆ ). is preferred.

The content of the hexafluorosilicic acid compound is preferably in the range of 0.01% by mass or more and 0.3% by mass or less with respect to the total mass of the fine processing agent, and 0.05% by mass or more and 0.15% by mass. A range of mass % or less is more preferable. By setting the content of the hexafluorosilicate compound to 0.01% by mass or more, the effect of suppressing the etching rate of the silicon oxide film can be maintained satisfactorily, and as a result, the etching rate of the silicon nitride film can be improved. can. On the other hand, by setting the content of the hexafluorosilicic acid compound to 0.3% by mass or less, the effect of suppressing the etching rate of the silicon oxide film can be maintained satisfactorily.

The water contained in the fine processing agent of the present embodiment is not particularly limited, but pure water, ultrapure water, and the like are preferable.

The content of water is preferably in the range of 5% by mass or more and 50% by mass or less, more preferably in the range of 10% by mass or more and 40% by mass or less with respect to the total mass of the fine processing agent.

The fine processing agent of the present embodiment consists of only the compound represented by the chemical formula (1), the inorganic phosphoric acid, the hexafluorosilicic acid compound, and water. It is also possible to add other additives. Other additives include, for example, known surfactants.

The method for producing the fine processing agent according to the present embodiment is not particularly limited, and various methods can be adopted. For example, the compound represented by Chemical Formula (1), the hexafluorosilicic acid compound, and the inorganic phosphoric acid can be added to water in any order or simultaneously to produce the fine processing agent of the present embodiment.

Depending on the desired purity of the microfabrication treatment agent, at least one of the compound represented by the chemical formula (1), inorganic phosphoric acid, hexafluorosilicic acid compound and water may be distilled, purified using an ion exchange resin, or purified using an ion exchange membrane. , electrodialysis, filtration, or the like, or circulating filtration of a fine processing agent, or the like.

As described above, the microfabrication treatment agent according to the present embodiment suppresses microfabrication of the silicon oxide film and is selective to the silicon nitride film in the laminated film including at least the silicon oxide film and the silicon nitride film. fine processing can be carried out satisfactorily. In addition, fine processing can be performed while reducing or preventing the deposition (generation) of the silicon compound derived from the hexafluorosilicic acid compound contained in the fine processing agent and adhering to the silicon oxide film to grow the film. Therefore, the microfabrication agent of the present embodiment is suitable for microfabrication such as wet etching in the manufacturing process of semiconductor devices, liquid crystal display devices, microelectronic devices, etc., which are becoming more highly integrated and miniaturized.

(Microfabrication method)
Next, a fine processing method using the fine processing agent of the present embodiment will be described below.
The microfabrication method of this embodiment is suitable for performing microfabrication on a laminated film including at least a silicon oxide film and a silicon nitride film.

The fine processing agent of this embodiment is employed in various wet etching methods. Wet etching methods include a batch type and a single wafer type, and the fine processing agent of the present invention can be employed in any of these methods. The batch-type wet etching method is superior in terms of throughput because a large number of wafers can be wet-etched at once. In the case of a single-wafer wet etching method, the problem of cross-contamination in the etching bath can be reduced or prevented.

Methods for bringing the fine processing agent into contact with the laminated film include an immersion method and a spray method. Of these contact methods, the immersion method is preferable because it can reduce or suppress composition changes due to evaporation of the fine processing agent during the process.

When the microfabrication agent is used as an etchant, the etching temperature (that is, the liquid temperature of the microfabrication agent) is preferably 180° C. or lower, more preferably 100° C. or higher and 160° C. or lower. °C or higher and 150 °C or lower, and particularly preferably 115 °C or higher and 140 °C or lower. By setting the etching temperature to 180° C. or lower, evaporation of the fine processing agent can be suppressed, and composition change of the fine processing agent can be prevented. In addition, it is possible to prevent difficulty in controlling the etch rate due to evaporation of the fine processing agent.

When using the fine processing agent of the present embodiment as an etching solution, for example, the etching temperature is 180° C. or less, preferably 100° C. or more and 160° C. or less, more preferably 105° C. or more and 150° C. or less, particularly preferably The etch rate for the silicon nitride film at 115° C. or higher and 140° C. or lower is preferably 1 nm/min or more, more preferably 2 nm/min or more, further preferably 3 nm/min or more, 4 nm/min or more is particularly preferable. By setting the etch rate to 1 nm/min or more, it is possible to prevent the microfabrication process such as etching from becoming long, and to suppress the decrease in processing (production) efficiency.

Furthermore, when using the fine processing agent of the present embodiment as an etching solution, for example, the etching temperature is 180° C. or less, preferably 100° C. or more and 160° C. or less, more preferably 105° C. or more and 150° C. or less, particularly preferably The etching rate for the silicon oxide film at 115° C. or higher and 140° C. or lower is preferably 0 nm/minute or more and less than 0.1 nm/minute. By setting the etch rate to 0 nm/min or more, the film growth of the silicon oxide film can be prevented. On the other hand, by setting the etch rate to less than 0.1 nm/min, microfabrication such as etching of the silicon oxide film can be suppressed, and selective microfabrication of the silicon nitride film can be further improved.

Here, the silicon oxide film is not particularly limited as long as it contains silicon (Si) and oxygen (O). Specifically, for example, a natural oxide film, a chemical oxide film, a silicon thermal oxide film, a non-doped silicate glass film, a phosphorus-doped silicate glass film, a boron-doped silicate glass film, a phosphorus boron-doped silicate glass film, and a TEOS (Tetraethyl Orthosilicate) film. , a fluorine-containing silicon oxide film, a carbon-containing silicon oxide film, a nitrogen-containing silicon oxide film, an SOG (Spin on glass) film, an SOD (Spin on dielectric) film, and the like.

In the silicon oxide film, the natural oxide film is a silicon oxide film formed on silicon during exposure to air at room temperature. A chemical oxide film is a film formed on silicon during cleaning with sulfuric acid/hydrogen peroxide water, for example. A silicon thermal oxide film is a film formed at a high temperature of 800 to 1000° C. by supplying water vapor or oxygen gas. In the non-doped silicate glass film, the phosphorus-doped silicate glass film, the boron-doped silicate glass film, the phosphorus boron-doped silicate glass film, the TEOS film, the fluorine-containing silicon oxide film, the carbon-containing silicon oxide film, and the nitrogen-containing silicon oxide film, A raw material gas such as silane can be supplied, and a silicon oxide film can be deposited by a CVD (Chemical Vapor Deposition) method. The SOG film and SOD film can be formed by a coating method such as a spin coater.

The silicon nitride film is not particularly limited as long as it contains silicon (Si) and nitrogen (N). Specific examples include a silicon nitride film, an oxygen-containing silicon nitride film, a carbon-containing silicon nitride film, and the like.

A method for forming the silicon nitride film is not particularly limited, and examples thereof include a CVD method and a PVD (Physical Vapor Deposition) method using silane gas, ammonia gas, and other raw material gases.

The CVD methods include PECVD (Plasma enhanced Chemical vapor deposition), ALD (Atomic layer deposition), MOCVD (Metalorganic Vapor Deposition), Cat-CVD (Catalytic Chemical Vapor Deposition), Thermal CVD. , and epitaxial CVD. Examples of the PVD method include film formation methods such as vacuum deposition, ion plating, ion beam deposition, and sputtering.

Preferred embodiments of the present invention will be described in detail below. However, unless otherwise specified, the materials and compounding amounts described in the examples are not intended to limit the scope of the present invention.

(Examples 1 to 5)
Phosphoric acid (H ₃ PO ₄ ), hexafluorosilicic acid, the compound represented by the above-described chemical formula (1), and water were mixed and stirred so that the mixing ratio shown in Table 1 was obtained. The liquid temperature of this mixed solution was adjusted to the temperature shown in Table 1 to prepare an etchant (fine processing agent) according to each example. As the compound represented by chemical formula (1), either compound A represented by chemical formula (5) or compound B represented by chemical formula (6) was used.

(Comparative Examples 1 to 3)
Phosphoric acid (H ₃ PO ₄ ), hexafluorosilicic acid, and water were mixed and stirred so as to have a mixing ratio shown in Table 1. The temperature of the mixed solution was controlled so as to be the temperature shown in Table 1, and an etchant (fine processing agent) according to each comparative example was prepared.

(Etch rate of silicon nitride film and silicon oxide film)
The film thickness of the silicon nitride film and the silicon oxide film before etching was measured using an optical film thickness measuring device (Nanospec M6100, manufactured by Nanometrics Japan Co., Ltd.).

Next, using the etchants according to Examples 1 to 5 and Comparative Examples 1 to 3, the silicon oxide film and the silicon nitride film were etched at each etching temperature shown in Table 1. The film thicknesses of the silicon oxide film and the silicon nitride film after etching were repeatedly measured at three different etching times to calculate the etch rate. Table 1 shows the results. The etching was performed by immersing the silicon oxide film and the silicon nitride film in each etchant.

Subsequently, the etch rate selectivity (silicon nitride film/silicon oxide film) was also calculated and evaluated. Table 1 shows the results.

(result)
As can be seen from the results in Table 1, the etching solutions of Comparative Examples 1 to 3 had a negative etching rate for the silicon oxide film, and the silicon oxide derived from hexafluorosilicic acid precipitated and adhered to the silicon oxide film. , it was confirmed that the film was growing. On the other hand, in the etching solutions of Examples 1 to 5, the precipitation of silicon oxide was suppressed, and the etch rate of the silicon oxide film could be suppressed to less than 0.1 nm/min. Furthermore, the etch rate selection ratio (silicon nitride film/silicon oxide film) of the silicon nitride film with respect to the silicon oxide film also shows a good value, and both can improve the selective etching of the silicon nitride film with respect to the silicon oxide film. rice field.

Claims (17)

A fine processing agent used for fine processing of a laminated film containing at least a silicon oxide film and a silicon nitride film,
a compound represented by the following chemical formula (1);
inorganic phosphoric acid;
A hexafluorosilicic acid compound,
including at least water;
A fine processing agent for selectively finely processing the silicon nitride film with respect to the silicon oxide film.

(X is a hydrogen atom, a silicon atom, or a functional group represented by the chemical formulas (2) to (4). R ¹ , R 2 and R ² in the chemical formulas (2) to (4) Each R ³ is independently a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms. alkynyl group, hydroxyalkyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, aminoalkoxy group having 1 to 20 carbon atoms, phosphate group, sulfate group, nitrile group, carboxyl group or acetoxy group represents any of n represents an integer of 1 to 4.) The fine processing agent according to claim 1, wherein the content of the compound represented by the chemical formula (1) is 0.001% by mass or more and 0.1% by mass or less with respect to the total mass of the fine processing agent. . 2. The fine processing agent according to claim 1, wherein the content of said inorganic phosphoric acid is 50% by mass or more and 90% by mass or less with respect to the total mass of said fine processing agent. 2. The fine processing agent according to claim 1, wherein the hexafluorosilicic acid compound contains at least one of hexafluorosilicic acid and ammonium hexafluorosilicate. The fine processing agent according to claim 1, wherein the content of the hexafluorosilicic acid compound is 0.01% by mass or more and 0.3% by mass or less with respect to the total mass of the fine processing agent. 2. The microfabrication agent according to claim 1, wherein said microfabrication agent has an etch rate of 1 nm/min or more at 180[deg.] C. or less with respect to said silicon nitride film. The silicon oxide film includes a natural oxide film, a chemical oxide film, a silicon thermal oxide film, a non-doped silicate glass film, a phosphorus-doped silicate glass film, a boron-doped silicate glass film, a phosphorus boron-doped silicate glass film, a TEOS film, and a fluorine-containing silicon oxide film. 2. The microfabrication agent according to claim 1, which is a film, a carbon-containing silicon oxide film, a nitrogen-containing silicon oxide film, an SOG film, or an SOD film. 2. The microfabrication agent according to claim 1, wherein the silicon nitride film is any one of a silicon nitride film, an oxygen-containing silicon nitride film, and a carbon-containing silicon nitride film. A microfabrication method for a laminated film containing at least a silicon oxide film and a silicon nitride film,
a compound represented by the following chemical formula (1);
inorganic phosphoric acid;
A hexafluorosilicic acid compound,
using a fine processing agent containing at least water,
A fine processing method for selectively finely processing the silicon nitride film with respect to the silicon oxide film.

(X is a hydrogen atom, a silicon atom, or a functional group represented by the chemical formulas (2) to (4). R ¹ , R 2 and R ² in the chemical formulas (2) to (4) Each R ³ is independently a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms. alkynyl group, hydroxyalkyl group having 1 to 20 carbon atoms, alkoxy group having 1 to 20 carbon atoms, aminoalkoxy group having 1 to 20 carbon atoms, phosphate group, sulfate group, nitrile group, carboxyl group or acetoxy group represents any of n represents an integer of 1 to 4.) 10. The fine processing method according to claim 9, wherein the content of the compound represented by the chemical formula (1) is 0.001% by mass or more and 0.1% by mass or less with respect to the total mass of the fine processing agent. . 10. The fine processing method according to claim 9, wherein the content of said inorganic phosphoric acid is 50% by mass or more and 90% by mass or less with respect to the total mass of said fine processing agent. 10. The microfabrication method according to claim 9, wherein the hexafluorosilicic acid compound contains at least one of hexafluorosilicic acid and ammonium hexafluorosilicate. 10. The fine processing method according to claim 9, wherein the content of said hexafluorosilicic acid compound is 0.01% by mass or more and 0.3% by mass or less with respect to the total mass of said fine processing agent. 10. The microfabrication method according to claim 9, wherein said microfabrication processing agent has an etch rate of 1 nm/min or more at 180[deg.] C. or less with respect to said silicon nitride film. 10. The microfabrication method of claim 9, wherein the microfabrication treatment agent has a temperature of 180[deg.]C or less. The silicon oxide film includes a natural oxide film, a chemical oxide film, a silicon thermal oxide film, a non-doped silicate glass film, a phosphorus-doped silicate glass film, a boron-doped silicate glass film, a phosphorus boron-doped silicate glass film, a TEOS film, and a fluorine-containing silicon oxide film. 10. The microfabrication method according to claim 9, wherein the substrate is any one of a film, a carbon-containing silicon oxide film, a nitrogen-containing silicon oxide film, an SOG film, and an SOD film. 10. The microfabrication method according to claim 9, wherein the silicon nitride film is one of a silicon nitride film, an oxygen-containing silicon nitride film, and a carbon-containing silicon nitride film.