JP2012033561A - Etchant for silicon nitride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etchant by which etching of silicon nitride is highly selectively performed without generating deposits after etching, in a step of removing silicon nitride from an electronic substrate having both a silicon dioxide layer and a silicon nitride layer.SOLUTION: The etchant for silicon nitride is used which contains, as essential components, a quaternary alkyl ammonium salt having a specific chemical structural formula, a basic compound, and an inorganic acid and/or an organic acid.

Description

The present invention relates to an etching solution for etching silicon nitride used for an insulating film of an electronic substrate such as a semiconductor device, a flat panel display, or a microelectromechanical system (MEMS), and a method of manufacturing an electronic substrate using the same.
More specifically, the present invention relates to an etching solution having an advantage that only silicon nitride can be removed with high selectivity in an electronic substrate having both silicon nitride and silicon dioxide.

Silicon nitride is a very important compound as a ceramic material and a semiconductor material, and is a compound that is chemically stable and has high corrosion resistance to acids other than hydrofluoric acid. Conventionally, as a method of etching silicon nitride, a method of etching using phosphoric acid at a high temperature of 150 ° C. or higher is known.

Although this method is most widely used, silicon nitride is not etched unless it is at a high temperature of 150 ° C. or higher. On the other hand, the temperature distribution of the etching solution tends to be non-uniform at 150 ° C. or higher. There was a problem that variations occurred.
In addition, etching using phosphoric acid has a problem that silicon nitride once dissolved is precipitated in phosphoric acid, and dust deposited on the electronic substrate adheres to cause a short circuit between adjacent cells.

On the other hand, as a method for etching silicon nitride at 100 ° C. or lower, a method using a fluorine-containing compound such as hydrofluoric acid or a salt thereof is known.
For example, a method of simultaneously etching silicon dioxide and silicon nitride with an etchant composed of hydrofluoric acid, ammonia, and a hydrophilic surfactant having an oxyethylene chain is disclosed (Patent Document 1).
However, in the method of Patent Document 1 using hydrofluoric acid, the etching rate ratio of silicon nitride to silicon dioxide is 0.1 or less, and silicon nitride can be etched when a fluorine-containing compound is used. There is a problem that even silicon dioxide, which is a peripheral semiconductor material that is not desired to be etched, is etched.
In addition, attempts have been made to control the etching rate of silicon dioxide and silicon nitride by selecting a solvent, but the etching rate ratio of silicon nitride to silicon dioxide was only about 1.2 (Patent Document 2). )

As another method for increasing the etching rate of silicon nitride, a method using an oxidizing solution such as hydrogen peroxide and dilute hydrofluoric acid (Patent Document 3) is known.
However, with the technique of Patent Document 3, it is still difficult to remove only silicon nitride with high selectivity.

Japanese Patent Application Laid-Open No. 7-21711 JP-A-11-112442 JP 2001-44167 A

It is an object of the present invention to provide an etchant that highly selectively etches silicon nitride and does not generate precipitates after etching in the step of removing silicon nitride from an electronic substrate having both silicon dioxide and silicon nitride. And

The inventors of the present invention have reached the present invention as a result of studies to achieve the above object.
That is, the present invention is an etching solution for the process of selectively removing silicon nitride from an electronic substrate having silicon nitride and silicon dioxide at the same time, comprising a compound (A) represented by the following general formula (1), ammonia And at least one basic compound (B) selected from the group consisting of an amine, a tetraalkylammonium hydroxide and a nitrogen-containing heterocyclic compound, and an inorganic acid (C1) and / or an organic acid (C2) as essential components An etching solution for silicon nitride; and a method of selectively removing silicon nitride from the surface of the electronic substrate having silicon nitride and silicon dioxide simultaneously using the etching solution. .

[Wherein, R ¹ is an aliphatic hydrocarbon group having 8 to 24 carbon atoms; R ^{2 to} R ⁴ are each independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 24 carbon atoms or a benzyl group; An integer of ^˜4 ; X ^f− represents a f-valent anion. ]

The present invention provides an effect that silicon nitride can be etched with high selectivity in the step of removing silicon nitride from an electronic substrate having silicon dioxide and silicon nitride at the same time, and precipitates are not generated after etching.

The etching solution for silicon nitride of the present invention is an etching solution for the step of selectively removing silicon nitride from an electronic substrate having both silicon nitride and silicon dioxide.
And it is the etching liquid for silicon nitride which has three components of a nitrogen-containing compound which has a specific chemical structure, a basic compound, and an acid as an essential component.
The basic compound is ammonia, amine, tetraalkylammonium hydroxide, nitrogen-containing heterocyclic compound, and the acid may be an inorganic acid or an organic acid.

In the present invention, examples of the electronic substrate having both silicon nitride and silicon dioxide to be etched include those used for semiconductors and flat panel displays. Examples of silicon nitride include low pressure chemical vapor deposition (LPCVD) and plasma. Examples thereof include those formed by chemical vapor deposition (PECVD) and atomic layer deposition (ALD). The silicon nitride may contain silicon dioxide. Examples of silicon dioxide include those formed by thermal oxidation, LPCVD, PECVD, and ALD.

In the present invention, examples of the silicon nitride etching method include immersion etching and single wafer etching.

  The etching solution of the present invention is usually used in the range of 25 to 150 ° C, preferably 50 to 100 ° C. If it is room temperature or more, it is preferable at the point of an etching rate, and if it is 150 degrees C or less, it is preferable at the point which does not produce a variation in an etching rate.

  The compound (A) represented by the following general formula (1), which is the first essential component of the present invention, has an action of imparting an etching rate ratio between silicon nitride and silicon dioxide. Examples of the compound (A) represented by the general formula (1) include quaternary ammonium salts (A1) and alkylamine salts (A2) having an alkyl group having 8 to 24 carbon atoms in the molecule. Can be mentioned.

[Wherein, R ¹ is an aliphatic hydrocarbon group having 8 to 24 carbon atoms; R ^{2 to} R ⁴ are each independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 24 carbon atoms or a benzyl group; An integer of ^˜4 ; X ^f− represents a f-valent anion. ]

R ¹ in the general formula (1) is an aliphatic hydrocarbon group having 8 to 24 carbon atoms, and represents a linear or branched alkyl group or alkenyl group.

Examples of the linear alkyl group include n-octyl group, n-nonyl group, n-decyl group, lauryl group, myristyl group, cetyl group, stearyl group, and behenyl group.
Examples of the linear alkenyl group include an oleyl group.
Examples of the branched alkyl group include 2-ethylhexyl group, isodecyl group, isododecyl group, and isooctadecyl group.

R ¹ is preferably an aliphatic hydrocarbon group having 8 to 24 carbon atoms, more preferably an aliphatic hydrocarbon group having 9 to 22 aliphatic carbon atoms, and particularly preferably an aliphatic hydrocarbon group having 10 to 18 carbon atoms. It is a hydrogen group. If the number of carbon atoms is 8 or more, it is preferable in terms of the etching rate ratio of silicon nitride and silicon dioxide.

In the general formula (1), R ^{2 to} R ⁴ are a hydrogen atom, an aliphatic hydrocarbon group having 1 to 24 carbon atoms or a benzyl group, and the aliphatic hydrocarbon group having 1 to 24 carbon atoms is linear or branched. Examples thereof include an alkyl group and an alkenyl group.

Examples of the aliphatic hydrocarbon group having 1 to 24 carbon atoms are the same as those exemplified for R ¹ .

Among these, R ^{2 to} R ⁴ are preferably an aliphatic hydrocarbon group having 1 to 24 carbon atoms, more preferably an aliphatic hydrocarbon group having 1 to 22 carbon atoms, and particularly preferably 1 carbon atom. ˜18 aliphatic hydrocarbon groups.

Specific examples of the quaternary ammonium (A1) in the general formula (1) include the following.
One having a long chain alkyl group (trimethyllauryl ammonium, trimethyl myristyl ammonium, trimethyl cetyl ammonium, trimethyl stearyl ammonium, trimethyl behenyl ammonium, trimethyl-2-ethylhexyl ammonium, dimethyl ethyl lauryl ammonium, dimethyl ethyl myristyl ammonium, dimethyl ethyl cetyl Ammonium, dimethylethyl stearyl ammonium, dimethyl ethyl-2-ethylhexyl ammonium, methyl diethyl lauryl ammonium, methyl diethyl myristyl ammonium, methyl diethyl cetyl ammonium, methyl diethyl stearyl ammonium, methyl diethyl-2-ethylhexyl ammonium, dimethyl n-decylbenzyl ammonium Dimethyl lauryl benzyl ammonium, dimethyl myristyl benzyl ammonium, dimethyl stearyl benzyl ammonium, dimethyl oleyl benzyl ammonium);
Having two long chain alkyl groups (dimethyldi n-octyl ammonium, dimethyl di n-decyl ammonium, dimethyl dilauryl ammonium, dimethyl distearyl ammonium, etc.); and having one long chain alkenyl group (8 to 22 carbon atoms) (Trimethyloleylammonium, dimethylethyloleylammonium, methyldiethyloleylammonium, etc.).

Specific examples of the alkylamine (A2) in the general formula (1) include n-octylamine, n-nonylamine, n-decylamine, laurylamine, n-myristylamine, cetylamine, stearylamine and the like.

In the general formula (1), X ^f− represents an f-valent anion, and specific examples include hydroxide, fluoride ion, hexafluorosilicate ion, hexafluorophosphate ion, tetrafluorosilicate ion, chloride ion. , Bromide ions, iodide ions, sulfate ions, phosphate ions, nitrate ions, acetate ions, trifluoroacetic acid ions, formate ions, oxalate ions, carbonate ions, methyl carbonate ions, and the like.

  Of the compound (A) represented by the general formula (1), cations such as trimethyl stearyl ammonium ion, trimethyl behenyl ammonium ion, and dimethyl distearyl ammonium ion are preferable from the viewpoint of the etching rate ratio between silicon nitride and silicon dioxide. Examples include salts of combinations of components and anions such as fluoride ions, hexafluorosilicate ions, hexafluorophosphate ions, tetrafluorosilicate ions, chloride ions, acetate ions, and methyl carbonate ions.

  The compound (A) represented by the general formula (1) can be used alone or in combination of two or more.

  The content of the compound (A) represented by the general formula (1) is preferably from 0.0001 to 10% by weight, more preferably from the viewpoint of selectivity and foaming, based on the total weight of the etching solution. 001 to 1% by weight, particularly preferably 0.005 to 0.5% by weight.

The basic compound (B), which is the second essential component of the present invention, acts as an etching agent and a pH adjuster.
The basic compound (B) of the present invention is ammonia, an amine or a tetraalkylammonium hydroxide, and a nitrogen-containing heterocyclic compound.

  Examples of the amine include aliphatic amine, alkanol amine, alkylene diamine, polyalkylene polyamine, aromatic amine, alicyclic amine, and guanidine.

Aliphatic amines include methylamine, ethylamine, propylamine, isopropylamine, butylamine, hexylamine, dimethylamine, ethylmethylamine, propylmethylamine, butylmethylamine, diethylamine, propylethylamine, diisopropylamine, trimethylamine, ethyldimethylamine , Diethylmethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine and the like.

  Examples of the alkanolamine include monoethanolamine, diethanolamine, triethanolamine, dimethylaminoethanol, diethylaminoethanol, 2-amino-2-methyl-1-propanol, N- (aminoethyl) ethanolamine, N, N-dimethyl-2. -Aminoethanol, 2- (2-aminoethoxy) ethanol, etc. are mentioned.

  Examples of the alkylene diamine include ethylene diamine, propylene diamine, trimethylene diamine, tetramethylene diamine, and hexamethylene diamine.

  Examples of the polyalkylene polyamine include diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethyleneheptamine, iminobispropylamine, bis (hexamethylene) triamine, and pentaethylenehexamine.

Examples of the aromatic amine include aniline, phenylenediamine, tolylenediamine, xylylenediamine, methylenedianiline, diphenyl ether diamine, naphthalene diamine, anthracene diamine and the like.

Examples of the alicyclic amine include isophoronediamine, cyclohexylenediamine, piperazine, N-aminoethylpiperazine, 1,4-diaminoethylpiperazine and the like.

  Examples of the tetraalkylammonium hydroxide include tetramethylammonium hydroxide, tetraethylammonium hydroxide, and choline.

  Examples of the nitrogen-containing heterocyclic compound include pyrrole, imidazole, pyrazole, oxazole, thiazole, pyridine, pyrimidine, pyridazine, pyrazine, bipyridine, phenanthroline and the like.

Of the basic compounds (B), preferred from the viewpoint of the etching rate of silicon nitride are ammonia, amine, tetraalkylammonium hydroxide, and nitrogen-containing heterocyclic compounds, and more preferred are ammonia and tetraalkylammonium hydroxide. is there.
It is.

  The basic compound (B) can be used alone or in combination of two or more.

The content of the basic compound (B) is preferably 0.001 to 50% by weight, more preferably 0.01 to 30% by weight, based on the total weight of the etching solution, from the viewpoint of the etching rate of silicon nitride. Particularly preferred is 0.1 to 10% by weight.
If the content is 0.001% by weight or more, it is preferable in terms of the etching rate ratio between silicon nitride and silicon dioxide, and if it is 50% by weight or less, it is preferable in terms of the etching rate of silicon nitride.

The inorganic acid (C1) and / or organic acid (C2), which is the third essential component of the present invention, acts as an etching agent and a pH adjuster.
Examples of the inorganic acid (C1) include hydrofluoric acid, hexafluorosilicic acid, hexafluorophosphoric acid, tetrafluorosilicic acid, silicic acid, boric acid, hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, phosphoric acid and the like. .
Of these inorganic acids, inorganic acids containing fluorine atoms are preferred, and hydrofluoric acid, hexafluorosilicic acid, hexafluorophosphoric acid and tetrafluorosilicic acid are particularly preferred.

Examples of the organic acid (C2) include carboxylic acid, organic phosphonic acid, and organic sulfonic acid.

Carboxylic acids include monocarboxylic acids such as formic acid and acetic acid, trifluoroacetic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, fumaric acid, phthalic acid, trimellitic acid, trimethyl Carbaryllic acid, hydroxybutyric acid, lactic acid, salicylic acid, malic acid, gallic acid, ascorbic acid, tartaric acid, citric acid, aspartic acid, glutamic acid, ethylenediaminetetraacetic acid, trans-1,2-cyclohexanediaminetetraacetic acid, nitrilotriacetic acid, diethylenetriaminepenta Examples include acetic acid and N- (2-hydroxyethyl) ethylenediamine-N, N ′, N′-triacetic acid.

  Examples of the organic phosphonic acid include methylphosphonic acid, ethylphosphonic acid, propylphosphonic acid, methylenebisphosphonic acid, ethylenediaminetetramethylenephosphonic acid, ethylenediaminedimethylenephosphonic acid, nitrilotrismethylenephosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid Etc.

  Examples of the organic sulfonic acid include benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, methanedisulfonic acid, 1,2-ethanedisulfonic acid, and the like.

  Of the inorganic acids (C1) and / or organic acids (C2), inorganic acids (C1) and organic phosphonic acids are preferred from the viewpoint of the etching rate of silicon nitride, and inorganic acids (C1) are particularly preferred. Are hydrofluoric acid, hexafluorosilicic acid, hexafluorophosphoric acid and tetrafluorosilicic acid.

  The inorganic acid (C1) and / or the organic acid (C2) can be used alone or in combination of two or more.

The content of the inorganic acid (C1) and / or the organic acid (C2) is preferably 0.001 to 50% by weight, more preferably 0, based on the total weight of the etching solution from the viewpoint of the etching rate of silicon nitride. 0.01 to 30% by weight, particularly preferably 0.1 to 10% by weight. If it is 0.001% by weight or more, it is preferable in terms of the etching rate of silicon nitride, and if it is 50% or less, it is preferable in terms of the etching rate ratio between silicon nitride and silicon dioxide.

  The etching solution of the present invention may further contain water and / or a water-miscible organic solvent for the purpose of improving the etching rate of silicon nitride and improving the etching rate ratio of silicon nitride and silicon dioxide. Examples of the water miscible organic solvent include alcohol, glycol ether, ether, ester, ketone, carbonate, amide and the like.

As alcohol, methanol, ethanol, isopropanol, n-propanol, n-hexanol, n-octanol, 2-ethylhexanol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexane Examples include diol, tetrahydrofurfuryl alcohol, glycerin and the like.

Examples of the glycol ether include propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether propionate, ethylene glycol monobutyl ether, and ethylene glycol monobutyl ether acetate.

Examples of the ether include diethyl ether, disopropyl ether, dibutyl ether, tetrahydrofuran, 1,4-dioxane and the like.

Examples of the ester include ethyl lactate, methyl 3-methoxypropionate, methyl acetate, ethyl acetate, propyl acetate, and γ-butyrolactone.

Examples of the ketone include acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclopentanone, and cyclohexanone.

Examples of the carbonate include dimethyl carbonate, diethyl carbonate, ethylene carbonate, and propylene carbonate.

Examples of the amide include N, N-dimethylacetamide, N, N-dimethylformamide and the like.

  From the viewpoint of the etching rate of silicon nitride and the etching rate ratio of silicon nitride and silicon dioxide, the solvent is preferably water, alcohol, glycol ether, carbonate, or a mixed solvent of at least two of these, more preferably water. Alcohol, glycol ether and carbonate.

  The etching solution of the present invention may contain a corrosion inhibitor such as triazoles, imidazoles, thiol compounds, sugar alcohols and the like as needed for the purpose of protecting the wiring metal.

Examples of triazoles include benzotriazole, o-tolyltriazole, m-tolyltriazole, p-tolyltriazole, carboxybenzotriazole, 1-hydroxybenzotriazole, nitrobenzotriazole, dihydroxypropylbenzotriazole and the like.
Examples of imidazoles include imidazole, benzimidazole, benzimidazole carboxylic acid, imidazole-2-carboxylic acid, imidazole-4-carboxylic acid, imidazole-2-carboxaldehyde, imidazole-4-carboxaldehyde, and 4-imidazole dithiocarboxylic acid. Is mentioned.
Examples of the thiol compound include thiourea, mercaptothiazole, mercaptoethanol, thioglycerol, and the like.
Examples of the sugar alcohol include erythritol, threitol, arabinitol, xylitol, ribitol, mannitol, sorbitol, and multitoinositol.

In the etching solution of the present invention, an antioxidant may be added as necessary for the purpose of protecting the wiring metal.
Examples of the antioxidant include catechin, tocopherol, catechol, methyl catechol, ethyl catechol, tert-butyl catechol, phenols such as gallic acid, methyl gallate, propyl gallate, 3-hydroxyflavone, ascorbic acid and the like.

  The etching solution of the present invention has a pH of 4.0 to 10.0 at 25 ° C., more preferably 5.0 to 9.0, particularly preferably 6.0 to 8.0. A pH of 4.0 or higher is preferable in terms of the etching rate ratio of silicon nitride and silicon dioxide, and a pH of 10.0 or lower is preferable in terms of the etching rate of silicon nitride. The pH can be measured according to JISK0400-12-10 by using the etching solution as a sample without diluting.

Etching solution of the present invention is the ratio of the etch rate of silicon nitride (V _SiN) and the etching rate of silicon dioxide _{(V SiO2) (V SiN)} / (V SiO2) is 10 or more. The etching rate can be calculated using an optical interference type film thickness measuring device.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

<Examples 1-7 and Comparative Examples 1-7>
The compound (A), basic compound (B), inorganic acid (C1), organic acid (C2) and solvent described in Table 1 are mixed in a polypropylene container and compared with the etching solution of the present invention. An etchant for was obtained. The pH of the etching solution was measured by the above method using a pH meter (manufactured by Toa Denpa Kogyo Co., Ltd., HM-30V).

In addition, the symbol in a table | surface represents the following compounds.
(A-1): Dimethyl distearyl ammonium chloride (A-2): Trimethyl behenyl ammonium chloride (A-3): Dimethyl distearyl ammonium acetate (B-1): 28% Ammonia water (B-2): 25% Tetramethylammonium hydroxide (TMAH) aqueous solution (B-3): ethylenediamine (C1-1): 50% hydrofluoric acid aqueous solution (C1-2): 90% phosphoric acid aqueous solution (C2-1): 60% 1 -Hydroxyethylidene-1,1-diphosphonic acid aqueous solution

As a performance evaluation, the following methods were used to determine the etching rate, the rate ratio, and the presence or absence of precipitates.

<Measurement of etching rate of silicon nitride and silicon dioxide and ratio thereof>
As a test piece for measuring the etching rate of silicon nitride, a test piece for measuring the etching rate of silicon dioxide using a 15 mm square silicon wafer (a) in which silicon nitride is formed to a thickness of 400 nm by LPCVD is used. In this example, a 15 mm square silicon wafer (b) on which silicon dioxide was deposited to a thickness of 100 nm by thermal oxidation was used.
(1) The film thickness before etching was calculated in advance from the measured value of the wavelength of incident light and the refractive index of each film using an optical interference type film thickness measuring device (Nanospec M6100A manufactured by Nanometrics).
(2) The above test pieces (a) and (b) are placed in a polypropylene sealed container containing the etching solutions prepared in Examples 1 to 7 and Comparative Examples 1 to 6 that have been temperature-controlled in advance at 80 ° C. for 30 minutes. Soaked.
Further, only the etching solution prepared in Comparative Example 7 was preliminarily adjusted to 160 ° C. and placed in a Teflon (registered trademark) sealed container, and the test pieces (a) and (b) were immersed for 30 minutes. .
(3) Each test piece (a) and (b) was taken out, washed with water, dried, and then the film thicknesses of silicon nitride and silicon dioxide were calculated with an optical interference film thickness measuring device.
(4) The etching rate of silicon nitride per minute (V _SiN ; nm / min) and the etching rate of silicon dioxide (V _SiO2 ; nm / min) were calculated from the change in film thickness before and after etching.
In Comparative Example 6, no decrease in thickness was observed.

<Presence / absence of precipitates>
The presence or absence of precipitates on the test pieces (a) and (b) was confirmed with a scanning electron microscope (S-4800 manufactured by Hitachi High-Tech).
The results are shown in Table 1.

The judgment criteria in Table 1 are as follows: None: No precipitates are observed in any of test pieces (a) and (b) Yes: Precipitates in any of test pieces (a) and (b) Is accepted

In Comparative Example 6 in which 90% phosphoric acid aqueous solution itself was used as an etching solution at 80 ° C., neither silicon nitride nor silicon dioxide was etched.
On the other hand, in Comparative Example 7, which was performed at 160 ° C. with the temperature raised in order to perform etching reliably, generation of precipitates was observed on the test pieces (a) and (b).

As can be seen from Table 1, in Examples 1 to 7, the etching rate ratio (V _SiN ) / (V _SiO2 ) between silicon nitride and silicon dioxide is high, and it can be seen that silicon nitride can be etched with high selectivity.
On the other hand, Comparative Example 1, Comparative Example 2 and Comparative Example 4 which do not contain the compound (A) of the present invention have a low etching rate ratio (V _SiN ) / (V _SiO2 ) between silicon nitride and silicon dioxide and are highly selective. It is hard to say that silicon nitride is being etched.
Further, Comparative Example 3 containing no basic compound (B) has a low etching rate ratio between silicon nitride and silicon dioxide, and it cannot be said that silicon nitride is etched with high selectivity.
For Comparative Example 5 containing neither inorganic acid (C1) nor organic acid (C2), the etching rate of silicon nitride is insufficient.
In Comparative Example 6 evaluated only with phosphoric acid at 80 ° C., no etching was observed. On the other hand, in Comparative Example 7 where only the phosphoric acid was evaluated at 160 ° C. by raising the temperature in order to increase the etching rate, precipitates are generated on the wafer, so it is necessary to remove them.

Since the etching solution for silicon nitride of the present invention is excellent in that it can highly selectively etch silicon nitride with respect to an article having silicon nitride and silicon dioxide at the same time, an electronic substrate, a flat panel display, It is useful as a chemical for process when manufacturing MEMS and semiconductor devices.

Claims (6)

An etching solution for the process of selectively removing silicon nitride from an electronic substrate having both silicon nitride and silicon dioxide, which is a compound (A) represented by the following general formula (1), ammonia, amine, tetraalkylammonium An essential component is at least one basic compound (B) selected from the group consisting of a hydroxide and a nitrogen-containing heterocyclic compound, and an inorganic acid (C1) and / or an organic acid (C2). Etching solution for silicon nitride.

[Wherein, R ¹ is an aliphatic hydrocarbon group having 8 to 24 carbon atoms; R ^{2 to} R ⁴ are each independently a hydrogen atom, an aliphatic hydrocarbon group having 1 to 24 carbon atoms or a benzyl group; An integer of ^˜4 ; X ^f− represents a f-valent anion. ]   The etching solution according to claim 1, wherein the inorganic acid (C1) is an acid containing a fluorine atom.   The etching solution according to claim 1 or 2, further comprising water and / or a water-miscible organic solvent.   The etching solution according to any one of claims 1 to 3, which has a pH of 4.0 to 10.0. Etchant of claims 1 to 4, wherein any ratio of the etch rate of silicon nitride (V _SiN) and the etching rate of silicon dioxide _{(V SiO2) (V SiN)} / (V SiO2) is 10 or more. A method for producing an electronic substrate comprising the step of selectively removing silicon nitride from an electronic substrate having silicon nitride and silicon dioxide simultaneously using the etching solution according to claim 1.