TW202344670A - Microprocessing treatment agent and microprocessing treatment method - Google Patents

Abstract

Provided are: a microprocessing treatment agent with which it is possible, in a laminated film including at least a silicon oxide film and a silicon nitride film, to satisfactorily perform selective microprocessing of the silicon nitride film while suppressing microprocessing of the silicon oxide film; and a microprocessing treatment method. This microprocessing treatment agent includes at least a compound represented by chemical formula (1), an inorganic phosphoric acid, a hexafluorosilicic acid compound, and water, said agent selectively microprocessing the silicon nitride film in relation to the silicon oxide film. (X is any one of H, Si, and functional groups represented by chemical formulas (2) to (4). R1 to R3 each independently represent any one of H, F, Cl, Br, I, alkyl groups, alkenyl groups, alkynyl groups, hydroxyalkyl groups, alkoxy groups, aminoalkoxy groups, phosphate groups, sulfate groups, nitrile groups, carboxyl groups, or acetoxy groups. n ranges from 1 to 4.).

Description

Microprocessing agent, and microprocessing method

The present invention relates to micro-processing agents and micro-processing methods used in micro-processing including etching and cleaning processes in the manufacture of semiconductor devices, liquid crystal display devices, micro electro mechanical systems (MEMS) devices, etc., especially It is a microprocessing agent and a microprocessing method used for microprocessing of a laminated film containing at least a silicon oxide film and a silicon nitride film.

In the manufacturing process of semiconductor devices, there is a step of patterning the silicon oxide film, silicon nitride film, silicon alloy, polycrystalline silicon film and metal film on the surface of the wafer into a target shape and etching it. The etching method is roughly divided into dry etching and wet etching.

Dry etching, also called anisotropic etching, uses reactive gases to remove target films on the wafer. Since dry etching is performed only in the direction perpendicular to the film surface of the target film, fine processing can be performed. But on the other hand, dry etching equipment is expensive and basically requires a batch process in which the reactor is kept in a vacuum state and the wafers are processed one by one. Therefore, it has the disadvantages of high manufacturing cost and low throughput.

Wet etching, also called isotropic etching, uses a liquid chemical solution to remove the target film. Since the wet etching method can process a large number of wafers at one time, it has the advantages of reducing costs and increasing throughput. But on the other hand, in the wet etching method, since the etching also reaches the lower part of the pattern, there is a disadvantage that the processing size is larger than the size of the pattern formed.

An example of a semiconductor device using wet etching in the manufacturing process is a 3D-NAND non-volatile memory. Conventional NAND-type non-volatile memories can be increased in capacity through miniaturization because they are planar, but this results in reduced electrical reliability, and miniaturization has reached its limit. Therefore, by overlapping the memory cells in the vertical direction, the capacity can be increased without reducing the size of the memory cells, which is the 3D-NAND type non-volatile memory.

The memory cells of 3D-NAND non-volatile memory are formed by alternately stacking silicon nitride films and silicon oxide films. Then, the alternately laminated silicon nitride film and silicon oxide film are dry etched to form micropores. The hole cross-section observation has a high aspect ratio with an etching width of several hundred nanometers and an etching depth of several microns. Therefore, when forming a recessed structure in the silicon nitride film in the hole, a wet etching method is used in order to etch only the silicon nitride film.

In addition, in the transistors of semiconductor devices such as logic and memory, the STI (Shallow Trench Isolation) process is also used to form an insulating film (silicon oxide film) embedded in order to electrically insulate between devices. Etching. Specifically, in the STI process, after the embedded insulating film is planarized by CMP (Chemical Mechanical Polishing) polishing, a wet etching method is applied in the step of selectively removing the silicon nitride film by leaving the silicon oxide film. .

In order to form a recessed structure in the aforementioned 3D-NAND non-volatile memory, or to use element separation in the STI process in a transistor, it is necessary to suppress the etching of the silicon oxide film as much as possible while selectively etching the silicon nitride film well.

Here, an example of a wet etching method for selectively etching a silicon nitride film is a method using high-temperature phosphoric acid as an etching liquid. However, in this wet etching method, the silicon oxide film is etched to some extent, and as a result, it may be difficult to finely process it into a desired shape.

Regarding this problem, for example, Patent Document 1 discloses an etching liquid containing a phosphoric acid solution, a silicon-containing compound (silicon oxide or polysiloxane), and a solvent. Furthermore, Patent Document 2 discloses an etching composition that further contains phosphoric acid in a compound and/or mixture of silicon and fluorine with an F/Si atomic ratio of less than 6.0. However, the etching liquid of Patent Document 1 or the etching composition of Patent Document 2 has a problem of generating precipitates derived from silicon on the silicon oxide film.

Patent Document 3 discloses an etching composition containing silicon nitride including a phosphorus compound, a boron compound and/or a fluoride thereof, and water. According to Patent Document 3, the etching composition can suppress damage to the silicon oxide film and suppress the generation of precipitates. However, the etching composition of Patent Document 3 has a problem that it cannot sufficiently suppress damage to the silicon oxide film and cannot obtain sufficient selective etching characteristics. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Publication No. 2000-58500 [Patent Document 2] Japanese Patent Application Publication No. 2007-12640 [Patent Document 3] Japanese Patent Application Publication No. 2009-21538

[Problem to be solved by the invention]

The present invention was completed in view of the above-mentioned problems, and an object thereof is to provide a laminated film including at least a silicon oxide film and a silicon nitride film, while suppressing microprocessing of the silicon oxide film and enabling good processing of the silicon nitride film. Micromachining treatment agent and micromachining treatment method for selective micromachining. [Means used to solve problems]

In order to solve the above problems, the microprocessing agent of the present invention is characterized by being a microprocessing agent used for microprocessing of a laminated film containing at least a silicon oxide film and a silicon nitride film, and the microprocessing agent contains at least the following chemical formula (1): compound, an inorganic phosphoric acid, a hexafluorosilicic acid compound and water, and the aforementioned silicon nitride film is selectively finely processed relative to the aforementioned silicon oxide film,

(X is a hydrogen atom, a silicon atom or any of the functional groups represented by the aforementioned chemical formulas (2) to (4). R ¹ , R ² and R ³ in the aforementioned chemical formulas (2) to (4) each represent independently Hydrogen atom, fluorine atom, chlorine atom, bromine atom, iodine atom, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, hydroxyalkane with 1 to 20 carbon atoms Any of a group, an alkoxy group with 1 to 20 carbon atoms, an amino alkoxy group with 1 to 20 carbon atoms, a phosphate group, a sulfate group, a nitrile group, a carboxyl group or an acetyloxy group, n represents 1 to 4 integer).

According to the above structure, by containing the hexafluorosilicic acid compound, microprocessing of the silicon oxide film can be suppressed, and selective microprocessing of the silicon nitride film can be improved. Furthermore, for example, compared with conventional microfabrication treatment agents containing silicon oxide or polysiloxane, the etching rate of the silicon nitride film can be increased. In addition, by containing the compound represented by the chemical formula (1), the precipitation (generation) of silicon compounds (such as silicon oxide, etc.) derived from hexafluorosilicic acid can be reduced or prevented. Thereby, it is possible to prevent or reduce the adhesion of the silicon compound to the surface of the silicon oxide film and the growth of the silicon oxide film.

In the above-mentioned composition, it is preferable that the content of the compound represented by the above-mentioned chemical formula (1) is 0.001 mass % or more and 0.1 mass % or less based on the total mass of the above-mentioned microprocessing treatment agent. By setting the content of the compound represented by the aforementioned chemical formula (1) to 0.001% by mass or more, the precipitation (generation) of the silicon compound (such as silicon oxide, etc.) derived from hexafluorosilicic acid can be further reduced or prevented, thereby preventing or reducing the amount of the compound represented by the chemical formula (1). Silicon compounds adhere to the surface of the silicon oxide film. As a result, the growth of the silicon oxide film can be further reduced or prevented. On the other hand, by setting the content of the compound represented by the aforementioned chemical formula (1) to 0.1% by mass or less, the etching rate suppression of the silicon oxide film can be maintained satisfactorily.

In the above-described composition, the content of the inorganic phosphoric acid is preferably 50 mass% or more and 90 mass% or less based on the total mass of the fine processing agent. By making the content of inorganic phosphoric acid fall within this numerical range, the etching rate of the silicon nitride film can be well maintained.

Furthermore, in the above-mentioned composition, it is preferable that the content of the hexafluorosilicic acid compound is 0.01 mass % or more and 0.3 mass % or less based on the total mass of the fine processing agent. By setting the content of the hexafluorosilicic acid compound to 0.01% by mass or more, the inhibitory effect on the etching rate of the silicon oxide film can be maintained, thereby enabling the silicon nitride film to have a good etching rate. On the other hand, by setting the content of the hexafluorosilicic acid compound to 0.3% by mass or less, the etching rate suppression of the silicon oxide film can be maintained satisfactorily.

In the above structure, it is preferable that the microprocessing agent has an etching rate of 1 nm/min or more for the silicon nitride film at 180° C. or lower. This can suppress the microfabrication process from taking a long time and suppress a decrease in processing (production) efficiency.

In the aforementioned composition, the aforementioned silicon oxide film can be a natural oxide film, a chemical oxidation film, a silicon thermal oxidation film, an undoped silicate glass film, a phosphorus-doped silicate glass film, a boron-doped silicate glass film, Any of phosphorus and boron doped silicate glass films, TEOS films, fluorine-containing silicon oxide films, carbon-containing silicon oxide films, nitrogen-containing silicon oxide films, SOG films or SOD films.

In the above structure, the silicon nitride film is any one 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 micromachining method for a laminated film including at least a silicon oxide film and a silicon nitride film, and uses at least a compound represented by the following chemical formula (1) and inorganic phosphoric acid , a microprocessing treatment agent of a hexafluorosilicic acid compound and water, which selectively microprocesses the aforementioned silicon nitride film relative to the aforementioned silicon oxide film,

(X is a hydrogen atom, a silicon atom or any of the functional groups represented by the aforementioned chemical formulas (2) to (4). In the aforementioned chemical formulas (2) to (4), R ¹ , R ² and R ³ each independently represent hydrogen. Atom, fluorine atom, chlorine atom, bromine atom, iodine atom, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, hydroxyalkyl group with 1 to 20 carbon atoms , any one of an alkoxy group with 1 to 20 carbon atoms, an amino alkoxy group with 1 to 20 carbon atoms, a phosphate group, a sulfate group, a nitrile group, a carboxyl group or an acetyloxy group, n represents 1 to 4 an integer).

According to the above configuration, using the microprocessing treatment agent for a laminated film including at least a silicon oxide film and a silicon nitride film can suppress microprocessing of the silicon oxide film, and at the same time, the silicon nitride film can be favorably selectively microprocessed. Furthermore, since the precipitation (generation) of a silicon compound (such as silicon oxide, etc.) derived from the hexafluorosilicic acid compound can be reduced or prevented, the silicon compound can also be reduced or prevented from adhering to the silicon oxide film to cause the silicon oxide film to grow. As a result, with the above structure, the fineness of the silicon oxide film can be suppressed in semiconductor manufacturing processes such as the formation of recessed structures in 3D-NAND non-volatile memories or the formation of element isolation using the STI process in transistors. By selectively fine-machining the silicon nitride film while processing, yield improvement can be achieved.

In the above-described structure, the content of the compound represented by the chemical formula (1) is preferably 0.001 mass% or more and 0.1 mass% or less based on the total mass of the fine processing agent. By setting the content of the compound represented by the aforementioned chemical formula (1) to 0.001% by mass or more, the precipitation (generation) of the silicon compound derived from hexafluorosilicic acid can be further reduced or prevented, and the adhesion of the silicon compound to silicon oxide can be prevented or reduced. membrane surface. As a result, the growth of the silicon oxide film can be further reduced or prevented. On the other hand, by setting the content of the compound represented by the aforementioned chemical formula (1) to 0.1% by mass or less, the etching rate suppression of the silicon oxide film can be maintained satisfactorily.

In the above-described composition, the content of the inorganic phosphoric acid is preferably 50 mass% or more and 90 mass% or less based on the total mass of the fine processing agent. By making the content of inorganic phosphoric acid fall within this numerical range, the etching rate of the silicon nitride film can be well maintained.

Furthermore, in the above-mentioned composition, it is preferable that the content of the hexafluorosilicic acid compound is 0.01 mass % or more and 0.3 mass % or less based on the total mass of the fine processing agent. By setting the content of the hexafluorosilicic acid compound to 0.01% by mass or more, the inhibitory effect on the etching rate of the silicon oxide film can be maintained, thereby enabling the silicon nitride film to have a good etching rate. On the other hand, by setting the content of the hexafluorosilicic acid compound to 0.3% by mass or less, the etching rate suppression of the silicon oxide film can be maintained satisfactorily.

In the above-described structure, it is preferable that the microprocessing agent has a temperature of 180°C or lower. This can suppress the evaporation of the microprocessing agent and prevent the composition of the microprocessing agent from changing. It also prevents the etching rate from being difficult to control due to evaporation of the microprocessing agent.

In the aforementioned composition, the aforementioned silicon oxide film can be a natural oxide film, a chemical oxidation film, a silicon thermal oxidation film, an undoped silicate glass film, a phosphorus-doped silicate glass film, a boron-doped silicate glass film, Any of phosphorus and boron doped silicate glass films, TEOS films, fluorine-containing silicon oxide films, carbon-containing silicon oxide films, nitrogen-containing silicon oxide films, SOG films or SOD films.

In the above structure, the silicon nitride film is any one of a silicon nitride film, an oxygen-containing silicon nitride film, or a carbon-containing silicon nitride film. [Effects of the invention]

The present invention exhibits the following effects by the means described above. That is, according to the present invention, in a laminated film including at least a silicon oxide film and a silicon nitride film, microfabrication of the silicon oxide film and film growth of the silicon oxide film can be prevented, and at the same time, selective processing of the silicon nitride film can be performed. Microprocessing agent and microprocessing method for microprocessing.

(Micro processing agent)

A microprocessing agent according to an embodiment of the present invention will be described below. The microprocessing treatment agent of this embodiment contains at least a compound represented by the following chemical formula (1), an inorganic phosphoric acid, a hexafluorosilicic acid compound, and water. The microprocessing treatment agent of this embodiment is suitable for use in a laminated film including at least a silicon oxide film and a silicon nitride film, and selectively microprocesses the silicon nitride film relative to the silicon oxide film.

In addition, in this specification, the so-called "microprocessing" means etching processing to finely process the surface of the laminated film, cleaning processing of the surface of the laminated film, etc. When the laminated film is etched, the microprocessing agent of this embodiment functions as an etching liquid. Furthermore, when cleaning is performed on the laminated film, the microprocessing treatment agent of this embodiment functions as a cleaning liquid.

By containing the compound represented by the chemical formula (1), the microprocessing agent of this embodiment can reduce or prevent the precipitation (generation) of a silicon compound (eg, silicon oxide, etc.) derived from a hexafluorosilicic acid compound. As a result, the silicon compound can be prevented from adhering to the silicon oxide film, and the growth of the silicon oxide film can be reduced or prevented.

In the chemical formula (1), X is a hydrogen atom, a silicon atom or a functional group represented by any one of the aforementioned chemical formulas (2) to (4). In the aforementioned chemical formulas (2) to (4), R ¹ , R ² and R ³ 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, a hydroxyalkyl group, an alkyl group, or an alkyl group. Any one of oxygen group, amino alkoxy group, phosphate group, sulfate group, nitrile group, carboxyl group or acetyloxy group. When X is a silicon atom, n=4, when X is a hydrogen atom or a functional group represented by chemical formula (2), n=1, when X is a functional group represented by chemical formula (3), n=2, and When using the functional group represented by chemical formula (4), n=3.

The alkyl groups in the aforementioned R ¹ , R ² and R ³ may be independently linear or branched. The carbon number of the alkyl group is 1 to 20, preferably 1 to 8, more preferably 1 to 4. Specific examples of the alkyl group include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tetradecyl, etc. Alkyl, cetyl and eicosanyl. Among these alkyl groups, from the viewpoint of good solubility in water, methyl, ethyl, propyl, butyl, etc. are preferred.

When a carbon number range is expressed in this specification, the range means the carbon number including all integers included in the range. Therefore, for example, an alkyl group with "carbon number 1 to 3" means all alkyl groups with carbon numbers 1, 2, and 3, that is, methyl, ethyl, and propyl.

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

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

The hydroxyalkyl groups of the aforementioned R ¹ , R ² and R ³ may be independently linear or branched. The carbon number of the hydroxyalkyl group is 1 to 20, preferably 1 to 8, more preferably 1 to 4. Specific examples of the hydroxyalkyl group include hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, hydroxypentyl, hydroxyhexyl, hydroxyheptyl, hydroxyoctyl, hydroxynonyl, hydroxydecyl, and hydroxyl. Undecyl, hydroxydodecyl, hydroxytridecyl, hydroxytetradecyl, hydroxypentadecyl, hydroxyhexadecyl, hydroxyheptadecyl, hydroxyoctadecyl, hydroxyninedecyl Alkyl and hydroxyeicosanyl, etc. Among these hydroxyalkyl groups, from the viewpoint of solubility in water, hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, etc. are preferred.

The alkoxy groups of the aforementioned R ¹ , R ² and R ³ may be independently linear or branched. The number of carbon atoms in the alkoxy group is 1 to 20, preferably 1 to 8, more preferably 1 to 4. Specific examples of the alkoxy group include methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, tert-butoxy, pentyloxy, and hexyloxy, Heptyloxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy and lauryloxy, etc. Among these alkoxy groups, from the viewpoint of solubility in water, methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy and tert-butoxy are preferred. wait.

The aforementioned aminoalkoxy groups of R ¹ , R ² and R ³ may be independently linear or branched. The number of carbon atoms in the amino alkoxy group is 1 to 20, preferably 1 to 8, and more preferably 1 to 4. Specific examples of the amino alkoxy group include, for example, amino methoxy group, amino ethoxy group, amino propoxy group, amino butoxy group, amino pentoxy group, amino hexyloxy group, and amino group. Heptyloxy, aminooctyloxy, aminononyloxy, aminodecyloxy and aminolauryloxy, etc. Among these amino alkoxy groups, from the viewpoint of good solubility in water, amino methoxy group, amino ethoxy group, amino propoxy group, amino butoxy group, etc. are preferred.

Specific examples of the sulfate ester group of R ¹ , R ² and R ³ include -SO ₄ group, -OS(=O) ₂ OCH ₃ group, -SO(=O) ₂ OCH ₂ CH ₃ group, etc. . Among these sulfate ester groups, from the viewpoint of solubility in water, -SO ₄ groups and the like are preferred.

The content of the compound represented by chemical formula (1) is preferably in the range of 0.001 mass % or more and 0.1 mass % or less, and more preferably in the range of 0.005 mass % or more and 0.05 mass % or less, based on the total mass of the microprocessing agent. . By setting the content of the compound represented by the chemical formula (1) to 0.001% by mass or more, the precipitation (generation) of the silicon compound derived from the hexafluorosilicic acid compound can be reduced or prevented from adhering to the silicon oxide film. As a result, the growth of the silicon oxide film can be further reduced or prevented. 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 favorably suppressed.

In this embodiment, inorganic phosphoric acid is contained in the microprocessing agent in order to prevent the etching rate of the silicon nitride film from decreasing.

The inorganic phosphoric acid is not particularly limited, and examples thereof include phosphoric acid (orthophosphoric acid, H ₃ PO ₄ ), diphosphoric acid (pyrophosphoric acid, H ₄ P ₂ O ₇ ), and tripolyphosphate (tripolyphosphate, H ₅ P ₃ O ₁₀ ), metaphosphate (HPO ₃ ), hexametaphosphate, etc. These inorganic phosphoric acids may be used individually by 1 type, or may be used in combination of 2 or more types. Among these inorganic phosphoric acids, phosphoric acid (orthophosphoric acid, H ₃ PO ₄ ) is preferred from the viewpoint of easy availability.

The content of inorganic phosphoric acid is preferably in the range of 50 mass % or more and 90 mass % or less, and more preferably in the range of 55 mass % or more and 85 mass % or less based on the total mass of the microprocessing agent. By setting the content of inorganic phosphoric acid to this value range, the etching rate of the silicon nitride film can be well maintained.

In this embodiment, the hexafluorosilicic acid compound can inhibit microprocessing of the silicon oxide film and improve selective microprocessing of the silicon nitride film. And compared with previous microfabrication treatment agents containing, for example, silicon oxide or polysiloxane, the hexafluorosilicic acid compound can also increase the etching rate of the silicon nitride film.

Here, in this specification, "hexafluorosilicic acid compound" means a general term for hexafluorosilicic acid and its salts (for example, ammonium salts, etc.). Specific examples of the hexafluorosilicic acid compound in this embodiment preferably include at least one of hexafluorosilicic acid (H ₂ SiF ₆ ) and ammonium hexafluorosilicate ((NH ₄ ) ₂ SiF ₆ ).

The content of the hexafluorosilicic acid compound is preferably in the range of 0.01 mass % or more and 0.3 mass % or less, and more preferably in the range of 0.05 mass % or more and 0.15 mass % or less based on the total mass of the microprocessing agent. By setting the content of the hexafluorosilicic acid compound to 0.01% by mass or more, the etching rate suppressing effect of the silicon oxide film can be maintained well, and as a result, the etching rate of the silicon nitride film can be improved. On the other hand, by setting the content of the hexafluorosilicic acid compound to 0.3% by mass or less, the etching rate suppressing effect on the silicon oxide film can be well maintained.

The water contained in the microprocessing treatment agent of this embodiment is not particularly limited, but pure water, ultrapure water, etc. are preferred.

The content of water is preferably in the range of 5 mass % or more and 50 mass % or less, and more preferably in the range of 10 mass % or more and 40 mass % or less based on the total mass of the microprocessing agent.

Except for the case where the microprocessing treatment agent of this embodiment is composed only of the compound represented by the chemical formula (1), an inorganic phosphoric acid, a hexafluorosilicic acid compound, and water, the microprocessing agent may also be used as long as the effect of the present invention is not inhibited. Other additives can be added. Examples of other additives include conventional surfactants.

The method of producing the microprocessing treatment agent of this embodiment is not particularly limited, and various methods can be used. For example, the microprocessing agent of this embodiment can be produced by adding the compound represented by the chemical formula (1), the hexafluorosilicic acid compound, and the inorganic phosphoric acid to water in any order or simultaneously.

Depending on the purity of the required microprocessing agent, at least one of the compound represented by the chemical formula (1), inorganic phosphoric acid, hexafluorosilicic acid, and water can be purified by distillation, ion exchange resin, ion exchange membrane, or electrolysis. It can be purified by dialysis, filtration, etc., and it can also be purified by circulating filtration of the microprocessing agent.

As described above, the microfabrication treatment agent of this embodiment can suppress the microfabrication of the silicon oxide film in a laminated film including at least a silicon oxide film and a silicon nitride film, and can also selectively microfabricate the silicon nitride film favorably. processing. Furthermore, it is possible to reduce or prevent the silicon compound derived from the hexafluorosilicic acid compound contained in the microprocessing agent from precipitating (generating) to adhere to the silicon oxide film and grow the film. Therefore, the microprocessing treatment agent of this embodiment is suitable for microprocessing such as wet etching in the manufacturing process of semiconductor elements, liquid crystal display elements, microelectromechanical devices, etc., which are progressing in high integration and miniaturization.

(Micro processing method) Next, a microprocessing method using the microprocessing agent of this embodiment will be described below. The micromachining method of this embodiment is suitable for micromachining a laminated film including at least a silicon oxide film and a silicon nitride film.

The microfabrication treatment agent of this embodiment can be used in various wet etching methods. As the wet etching method, there are batch type, single-wafer type, etc., and the microfabrication treatment agent of the present invention can be used in any method. In the case of the batch wet etching method, a large number of wafers can be wet-etched at one time, so it is excellent in terms of throughput. In the case of a single-chip wet etching method, cross-contamination problems in the etching tank can be reduced or prevented.

Examples of methods for bringing the microprocessing treatment agent into contact with the laminated film include dipping and spraying. Among these contact methods, the immersion method is preferable because it can reduce or suppress the composition change caused by the evaporation of the microprocessing agent in the step.

When using a microprocessing agent as the etching liquid, the etching temperature (i.e., the liquid temperature of the microprocessing agent) is preferably below 180°C, more preferably between 100°C and below 160°C, and more preferably between 105°C and 150°C. below, particularly preferably above 115°C and below 140°C. By setting the etching temperature to 180° C. or lower, evaporation of the microprocessing agent can be suppressed and changes in the composition of the microprocessing agent can be prevented. In addition, it can prevent the etching rate from being difficult to control due to evaporation of the microprocessing agent.

When using the microprocessing treatment agent of this embodiment as an etching liquid, the etching temperature is, for example, 180°C or lower, preferably 100°C or higher and 160°C or lower, more preferably 105°C or higher and 150°C or lower, particularly preferably 115°C or higher, The etching rate of the silicon nitride film below 140°C is preferably 1 nm/min or more, more preferably 2 nm/min or more, more preferably 3 nm/min or more, particularly preferably 4 nm/min or more. By setting the etching rate to 1 nm/min or more, it is possible to prevent microprocessing such as etching from becoming longer, thereby suppressing a decrease in processing (production) efficiency.

Furthermore, when using the micromachining treatment agent of this embodiment as an etching liquid, the etching temperature is, for example, 180°C or lower, preferably 100°C or higher and 160°C or lower, more preferably 105°C or higher and 150°C or lower, particularly preferably 115°C or higher, The etching rate of the silicon oxide film below 140°C is preferably above 0 nm/min and less than 0.1 nm/min. By setting the etching rate to 0 nm/min or more, the growth of the silicon oxide film can be prevented. On the other hand, by setting the etching rate to less than 0.1 nm/min, microprocessing such as etching of the silicon oxide film can be suppressed, and selective microprocessing 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). Specific examples include natural oxide film, chemical oxidation film, silicon thermal oxidation film, undoped silicate glass film, phosphorus-doped silicate glass film, boron-doped silicate glass film, phosphorus-boron-doped silicate glass film, and phosphorus-boron doped silicate glass film. Heterosilicate glass film, TEOS (Tetraethyl Orthosilicate: tetraethyl silicate) film, fluorine-containing silicon oxide film, carbon-containing silicon oxide film, nitrogen-containing silicon oxide film, SOG (Spin on glass: spin-on glass) film Or SOD (Spin on dielectroric: spin-on dielectric material) film, etc.

Among the aforementioned silicon oxide films, the so-called natural oxide film is a silicon oxide film formed on silicon during exposure to the atmosphere at room temperature. And the chemical oxidation film is a film formed on silicon during cleaning with sulfuric acid/hydrogen peroxide water, for example. Silicon thermal oxidation film is a film formed at a high temperature of 800~1000℃ by supplying water vapor or oxygen. About undoped silicate glass membrane, phosphorus-doped silicate glass membrane, boron-doped silicate glass membrane, phosphorus-boron doped silicate glass membrane, TEOS membrane, fluorine-containing silicon oxide membrane, carbon-containing oxidation The silicon film and the nitrogen-containing silicon oxide film are formed by supplying raw material gases such as silane and depositing the silicon oxide film through the CVD (Chemical vapor deposition) method. SOG film and SOD film can be formed by coating using a spin coater or the like.

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.

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

Examples of the aforementioned CVD methods include PECVD (Plasma enhanced chemical vapor deposition), ALD (Atomic layer deposition), MOCVD (organic metal vapor deposition), and catalyst-CVD (catalyst-CVD). Film formation methods such as media chemical vapor deposition), thermal CVD, epitaxial CVD, etc. Examples of the aforementioned PVD method include film-forming methods such as vacuum evaporation, ion plating, ion beam deposition, and sputtering. [Example]

Below, preferred embodiments of the present invention will be illustrated in detail. However, the materials, compounding amounts, etc. described in this example are not limited to the scope of the present invention unless otherwise specified.

(Examples 1 to 5) Phosphoric acid (H ₃ PO ₄ ), hexafluorosilicic acid, the compound represented by the above chemical formula (1), and water were mixed and stirred so as to achieve the mixing ratio shown in Table 1. The temperature of this mixed liquid was adjusted so that the liquid temperature would be the temperature shown in Table 1, and the etching liquid (micromachining agent) of each Example was prepared. As the compound represented by the chemical formula (1), either the compound A represented by the following chemical formula (5) or the compound B represented by the chemical formula (6) is 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 each of these mixed liquids was adjusted so that the liquid temperature would be the temperature shown in Table 1, and the etching liquid (micromachining treatment agent) of each comparative example was prepared.

(Etching 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 Japan Nanometrics Co., Ltd.).

Next, the silicon oxide film and the silicon nitride film were etched using the etching solutions of Examples 1 to 5 and Comparative Examples 1 to 3 at the etching temperatures shown in Table 1. According to the film thickness of the silicon oxide film and the silicon nitride film after etching, the determination of three different etching times was repeated, and the etching rate was calculated. The results are shown in Table 1. Moreover, etching is performed by immersing a silicon oxide film and a silicon nitride film in each etching liquid.

Next, the etching rate selectivity ratio (silicon nitride film/silicon oxide film) was also calculated and evaluated. The results are shown in Table 1.

(result) From the results in Table 1, it can be understood that the etching solutions of Comparative Examples 1 to 3 confirmed that the etching rate of the silicon oxide film was negative, and silicon oxide derived from hexafluorosilicic acid precipitated and adhered to the silicon oxide film, and the film grew. On the other hand, the etching solutions of Examples 1 to 5 suppressed the precipitation of silicon oxide, and the etching rate of the silicon oxide film did not reach 0.1 nm/min. In addition, the etching rate selectivity ratio (silicon nitride film/silicon oxide film) of the silicon nitride film relative to the silicon oxide film also shows a good value, which can improve the etching rate selectivity of the silicon nitride film relative to the silicon oxide film. eclipse.

Claims (17)

A microprocessing treatment agent used for microprocessing of a laminated film containing at least a silicon oxide film and a silicon nitride film, which contains at least a compound represented by the following chemical formula (1), inorganic phosphoric acid, hexafluoride a silicic acid compound, and water, and the silicon nitride film is selectively finely processed relative to the silicon oxide film, (X is a hydrogen atom, a silicon atom or any of the functional groups represented by the aforementioned chemical formulas (2) to (4). R ¹ , R ² and R ³ in the aforementioned chemical formulas (2) to (4) each represent independently Hydrogen atom, fluorine atom, chlorine atom, bromine atom, iodine atom, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, hydroxyalkane with 1 to 20 carbon atoms Any of a group, an alkoxy group with 1 to 20 carbon atoms, an amino alkoxy group with 1 to 20 carbon atoms, a phosphate group, a sulfate group, a nitrile group, a carboxyl group or an acetyloxy group, n represents 1 to 4 integer). The microprocessing agent of claim 1, wherein the content of the compound represented by the chemical formula (1) is 0.001 mass% or more and 0.1 mass% or less relative to the total mass of the microprocessing agent. The microprocessing agent according to claim 1, wherein the content of the inorganic phosphoric acid is 50 mass% or more and 90 mass% or less relative to the total mass of the microprocessing agent. The microfabrication treatment agent of claim 1, wherein the hexafluorosilicic acid compound includes at least one of hexafluorosilicic acid and ammonium hexafluorosilicate. The microprocessing agent of claim 1, wherein the content of the hexafluorosilicic acid compound is 0.01 mass% or more and 0.3 mass% or less relative to the total mass of the microprocessing agent. The microfabrication treatment agent of claim 1, wherein the microfabrication treatment agent has an etching rate of 1 nm/min or more for the silicon nitride film at 180° C. or below. Such as the microprocessing treatment agent of claim 1, wherein the aforementioned silicon oxide film is a natural oxide film, a chemical oxidation film, a silicon thermal oxide film, an undoped silicate glass film, a phosphorus-doped silicate glass film, or a boron-doped Any of silicate glass membrane, phosphorus-boron doped silicate glass membrane, TEOS membrane, fluorine-containing silicon oxide film, carbon-containing silicon oxide film, nitrogen-containing silicon oxide film, SOG film or SOD film. The microfabrication treatment agent of claim 1, wherein the silicon nitride film is any one of a silicon nitride film, an oxygen-containing silicon nitride film, or 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, using at least a compound represented by the following chemical formula (1), inorganic phosphoric acid, and hexafluorosilicic acid compound, and a water microprocessing treatment agent that selectively microprocesses the silicon nitride film relative to the silicon oxide film, (X is a hydrogen atom, a silicon atom or any of the functional groups represented by the aforementioned chemical formulas (2) to (4). In the aforementioned chemical formulas (2) to (4), R ¹ , R ² and R ³ each independently represent hydrogen. Atom, fluorine atom, chlorine atom, bromine atom, iodine atom, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, hydroxyalkyl group with 1 to 20 carbon atoms , any one of an alkoxy group with 1 to 20 carbon atoms, an amino alkoxy group with 1 to 20 carbon atoms, a phosphate group, a sulfate group, a nitrile group, a carboxyl group or an acetyloxy group, n represents 1 to 4 an integer). The microfabrication treatment method of Claim 9, wherein the content of the compound represented by the aforementioned chemical formula (1) is 0.001 mass% or more and 0.1 mass% or less relative to the total mass of the aforementioned microfabrication treatment agent. The microprocessing method of claim 9, wherein the content of the inorganic phosphoric acid is 50 mass% or more and 90 mass% or less relative to the total mass of the microprocessing agent. The microfabrication method of claim 9, wherein the hexafluorosilicic acid compound includes at least one of hexafluorosilicic acid and ammonium hexafluorosilicate. The microprocessing method of claim 9, wherein the content of the hexafluorosilicic acid compound is 0.01 mass% or more and 0.3 mass% or less relative to the total mass of the microprocessing agent. The microfabrication treatment method of claim 9, wherein the microfabrication treatment agent has an etching rate of 1 nm/min or more for the silicon nitride film at 180° C. or below. The micromachining method of claim 9, wherein the micromachining agent has a temperature of 180°C or lower. Such as the micro processing method of claim 9, wherein the aforementioned oxide silicon film is a natural oxide film, a chemical oxide film, a silicon thermal oxide film, an undoped silicate glass film, a phosphorus-doped silicate glass film, or a boron-doped film. Any of silicate glass membrane, phosphorus-boron doped silicate glass membrane, TEOS membrane, fluorine-containing silicon oxide film, carbon-containing silicon oxide film, nitrogen-containing silicon oxide film, SOG film or SOD film. The microfabrication method of claim 9, wherein the silicon nitride film is any one of a silicon nitride film, an oxygen-containing silicon nitride film, or a carbon-containing silicon nitride film.