TW201802231A - Etching solution for silicon nitride - Google Patents

Abstract

The present invention relates to an etching solution for a silicon substrate, and more specifically, to an etching solution which provides a passivation effect on a silicon oxide film when a silicon nitride film is etched, thereby increasing the selectivity to the silicon nitride film compared to the silicon oxide film; and at the same time, does not use any additional silicon additive in the etching solution to prevent the generation of silicon-based particles.

Description

Silicon Nitride Film Etching Solution

The present invention relates to a silicon nitride film etching solution capable of suppressing generation of silicon-based particles when silicon nitride film etching occurs.

Generally, a conventional wet etching method is an etching method using a silicon nitride film on a silicon wafer, using phosphoric acid as an etching solution. When only pure phosphoric acid is used for the etching of the silicon nitride film, a problem may occur in that not only the silicon nitride film but also the silicon oxide film is etched with the miniaturization of the device, thereby causing various defects and patterns. Abnormal, so it is necessary to further reduce the etching rate of the silicon oxide film.

On the other hand, in order to further increase the etching rate of the silicon nitride film, attempts have been made to use a compound containing fluorine as an additive. However, fluorine has the disadvantage of increasing the etching rate of the silicon oxide film.

Therefore, recently, in order to increase the etching rate of a silicon nitride film and decrease the etching rate of a silicon oxide film, phosphoric acid is used together with a silicon additive. Silane compounds that are mainly used as silicon additives have low solubility in etching solutions that basically contain phosphoric acid. Therefore, in order to increase the solubility of the silane compounds in the etching solution, a silane in which silicon atoms are combined with a hydrophilic functional group (for example, a hydroxyl group) is used. Compound.

In this way, when a silane in which a hydrophilic functional group is combined with a silicon atom is used When the compound is used as a silicon additive, proper solubility of the silane compound in the etching solution is ensured. However, in order to increase the etching selection ratio of the silicon nitride film, when the concentration of the silane compound in the etching solution is increased, not only the etching speed of the silicon oxide film is changed, but also the etching speed of the silicon nitride film is changed, thereby producing The problem of reduced productivity.

In addition, by using a silane compound as a silicon additive, the increased silicon concentration in the etching solution can act as a source (nucleus or seed) of silicon-based particles, and cause a substrate failure during etching or a cleaning process after etching. the reason.

An object of the present invention is to provide a silicon nitride film etching solution capable of improving a selectivity ratio of a silicon nitride film to a silicon nitride film based on the use of a silicon additive based on a silicon additive.

Another object of the present invention is to provide a silicon nitride film etching solution capable of compensating for a decrease in the etching rate due to the use of a silicon additive in accordance with the use of a fluorine-containing compound.

In order to solve the above technical problems, according to an embodiment of the present invention, a silicon nitride film etching solution is provided, including: an aqueous solution containing at least one of an inorganic acid and an organic acid; and a first silane compound containing 1 to 6 silicon An atom containing at least one silicon atom combined with three or more hydrophilic functional groups; a second silane compound containing 1 to 6 silicon atoms; the number of hydrophilic functional groups combined with one silicon atom is at most two; And fluorinated compounds.

The hydrophilic functional group may be a functional group capable of being substituted by a hydroxyl group or a hydroxyl group under a pH condition of the silicon nitride film etching solution.

Furthermore, according to another embodiment of the present invention, a post-etching cleaning solution is provided. After the silicon substrate is etched with an etching solution containing a silicon additive, the silicon-based particles can be reduced or suppressed during cleaning.

The silicon nitride film etching solution of the present invention has the advantage that the selection ratio of the silicon nitride film with respect to the silicon oxide film can be increased according to the use of silicon additives of the silane compound type, and can further include fluorine Compound that compensates for the decreased etch rate with the use of silicon additives.

In addition, according to the use of dissimilar silane compounds having different numbers of hydrophilic functional groups combined with silicon atoms, the silicon nitride film etching solution of the present invention can prevent the etching rate of the silicon oxide film from being increased due to excessive fluorine existing in the etching solution. .

In addition, the silicon nitride film etching solution of the present invention can effectively suppress the generation of silicon-based particles, and thus can prevent the failure or failure of the silicon substrate that occurs with the generation of silicon-based particles when cleaning during or after etching. Failure of etching and cleaning equipment.

In particular, according to the present invention, when an etched silicon substrate is cleaned, a silane compound represented by Chemical Formula 3 replaces a hydroxy group of a silicon particle containing a hydroxy group present in a cleaning solution with a siloxane group in a form that cannot be polymerized. This prevents the silicon-based particles from growing and precipitating.

According to an embodiment of the present invention, a silicon nitride film etching solution may be provided, including: an aqueous solution (hereinafter, referred to as an aqueous solution of an acid), at least one acid selected from an inorganic acid or an organic acid; a first silane compound, including 1 2 to 6 silicon atoms, including at least one silicon atom combined with three or more hydrophilic functional groups; a second silane compound, containing 1 to 6 silicon atoms, and the number of hydrophilic functional groups combined with one silicon atom Up to two; and fluorinated compounds.

The inorganic acid may be at least one selected from the group consisting of sulfuric acid, nitric acid, phosphoric acid, silicic acid, hydrofluoric acid, boric acid, hydrochloric acid, and perchloric acid. In addition to the above-mentioned inorganic acids, anhydrous phosphoric acid, pyrophosphoric acid, or polyphosphoric acid can be used.

The organic acid may be at least one selected from the group consisting of acetic acid, citric acid, formic acid, gluconic acid, lactic acid, oxalic acid, tartaric acid, and bicarbonate. In addition to the above organic acids, organic acids such as propionic acid, butyric acid, palmitic acid, stearic acid, oleic acid, malonic acid, succinic acid, maleic acid, glycolic acid, and glutaric acid can be used. , Adipic acid, sulfosuccinic acid, valeric acid, hexanoic acid, caprylic acid, capric acid, lauric acid, myristic acid, lactic acid, malic acid, citric acid, tartaric acid, benzoic acid, salicylic acid, p-toluenesulfonic acid, Naphthoic acid, niacin, toluic acid, anisic acid, cumic acid, and phthalic acid. If necessary, an aqueous solution of an acid containing a mixed acid of an inorganic acid and an organic acid can also be used.

Among them, the inorganic acid and the organic acid can exist in an aqueous solution in the form of a salt, and preferably, the salt is in the form of an ammonium salt.

The acid aqueous solution is a component that prevents the silane compounds in various forms existing in the etching solution from becoming silicon-based particles by maintaining the pH of the etching solution.

According to an embodiment, preferably, the aqueous solution of 60 to 90 parts by weight of the acid is contained with respect to 100 parts by weight of the silicon nitride film etching solution.

When the content of the acidic aqueous solution is less than 60 parts by weight with respect to 100 parts by weight of the silicon nitride film etching solution, the etching rate of the silicon nitride film can be reduced, so that the silicon nitride film is not sufficiently etched or etched. There is a concern that the process efficiency of the silicon nitride film will decrease.

On the contrary, when the content of the acidic aqueous solution is more than 90 parts by weight relative to 100 parts by weight of the silicon nitride film etching solution, not only the etching rate of the silicon nitride film is excessively increased, but also as the etching proceeds rapidly to oxidation Silicon film can reduce the selection ratio of silicon nitride film relative to silicon oxide film. In addition, as the silicon oxide film is etched, the silicon substrate may be defective.

According to an embodiment of the present invention, in order to improve the nitridation with respect to the silicon oxide film, In the selection ratio of the silicon film, the silicon nitride film etching solution includes a first silane compound represented by the following Chemical Formula 1 or Chemical Formula 2.

As shown in the following Chemical Formula 1, in the present invention, the first silane compound may be defined as a compound in which one silicon atom is combined with a functional group of R ₁ to R ₄ . Among them, at least three of R ₁ to R ₄ are hydrophilic functional groups.

其中，R₁至R₄分別獨立地選自親水性官能團或氫、C₁-C₁₀烷基、C₆-C₁₂環烷基、包含至少一個雜原子的C₂-C₁₀雜烷基、C₂-C₁₀烯基、C₂-C₁₀炔基、C₁-C₁₀鹵代烷基、C₁-C₁₀氨基烷基、芳基、雜芳基、芳烷基、矽氧基及矽氧烷的官能團。

Wherein R ₁ to R ₄ are each independently selected from a hydrophilic functional group or hydrogen, a C ₁ -C ₁₀ alkyl group, a C ₆ -C ₁₂ cycloalkyl group, a C ₂ -C ₁₀ heteroalkyl group containing at least one hetero atom, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl, siloxy and siloxy Functional group.

And, as shown in the following Chemical Formula 2, in the present invention, the first silane compound may be defined as a silane compound continuously bonded to at least two silicon atoms.

其中，R₅至R₁₀分別獨立地選自親水性官能團或氫、C₁-C₁₀烷基、C₆-C₁₂環烷基、包含至少一個雜原子的C₂-C₁₀雜烷基、C₂-C₁₀烯基、C₂-C₁₀炔基、C₁-C₁₀鹵代烷基、C₁-C₁₀氨基烷基、芳基、雜芳基、芳烷基、矽氧基及矽氧烷中的官能團，n為1至5的整數。

Wherein R ₅ to R ₁₀ are each independently selected from a hydrophilic functional group or hydrogen, a C ₁ -C ₁₀ alkyl group, a C ₆ -C ₁₂ cycloalkyl group, a C ₂ -C ₁₀ heteroalkyl group containing at least one hetero atom, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl, siloxy and siloxy The functional group in the alkane, n is an integer of 1 to 5.

That is, the first silane compound contains one to six silicon atoms, including three or more silicon atoms. At least one silicon atom combined with a hydrophilic functional group, thereby ensuring sufficient solubility in a silicon nitride film etching solution containing an aqueous solution of an acid, and forming a relatively strong hydrophilicity with a silicon substrate, especially with a silicon oxide film interaction.

By the strong hydrophilic interaction, the first silane compound attached to the surface of the silicon oxide film can prevent the inorganic acid or fluorine-containing compound from being etched from the silicon oxide film.

The hydrophilic functional group bonded to the silicon atom refers to a functional group capable of being substituted by a hydroxyl group or under the pH condition of an aqueous solution of an acid.

Among them, non-limiting examples of functional groups which may be substituted by a hydroxyl group under the pH condition of an aqueous acid solution are amino, halo, sulfonic, phosphonic, phosphoric, thiol, alkoxy, amido, The ester group, acid anhydride group, fluorenyl halide group, cyano group, carboxyl group, and azole group are not limited to the above functional groups, and it should be understood that, under the pH conditions of an acidic aqueous solution, any functional group that may be substituted by a hydroxyl group is also included.

In the present invention, the pH condition of the aqueous acid solution is 4 or less. When the pH condition of the aqueous acid solution is greater than 4, the stability of the first silane compound present in the silicon nitride film etching solution is lowered due to a relatively high pH, and there is a concern that it acts as a source of silicon-based particles.

In the present invention, halogen means fluorine (-F), chlorine (-Cl), bromine (-Br), or iodine (-I), and haloalkyl means an alkyl substituted with the above-mentioned halogen. For example, a halomethyl group is a methyl group (-CH ₂ X, -CHX _2- , or -CX ₃ ) in which at least one of the hydrogens of the methyl group is replaced by a halogen.

Also, in the present invention, alkoxy refers to both -O- (alk) yl and -O- (non-substituted cycloalkane) groups, and has one or more ether groups and 1 to 10 carbon atoms. Linear or branched hydrocarbons.

Specifically, including methoxy, ethoxy, propoxy, isopropoxy, n-butoxy Base, tert-butoxy, sec-butoxy, n-pentyloxy, n-hexyloxy, 1,2-dimethylbutoxy, cyclopropoxy, cyclobutoxy, cyclopentyloxy, cyclohexyloxy But not limited to this.

When R _a (wherein a is an integer selected from 1 to 4) is an alkenyl or alkynyl group, it may be an sp ² -hybridized carbon of an alkenyl group or an sp-hybridized carbon of an alkynyl group or directly The sp ² -hybridized carbon of an alkenyl group or the sp ³ -hybridized carbon of an alkyl group combined with the sp ² -hybridized carbon of an alkynyl group is indirectly bonded.

In the present invention, the C _a -C _b functional group refers to a functional group having a to b carbon atoms. For example, a C _a -C _b alkyl group has a carbon atom of a to b, and includes a saturated aliphatic group such as a linear alkyl group and a branched alkyl group. The linear or branched alkyl group has 10 or less in the main chain (for example, C ₁ -C ₁₀ straight chain, C ₃ -C ₁₀ branched chain), preferably 4 or less, more preferably Ground has 3 or less carbon atoms.

Specifically, the alkyl group may be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pent-1-yl, pent-2-yl, pentyl -3-yl, 3-methylbut-1-yl, 3-methylbut-2-yl, 2-methylbut-2-yl, 2,2,2-trimethylether-1-yl, N-hexyl, n-heptyl and n-octyl.

In the present invention, unless defined differently, aryl refers to a monocyclic or fused ring or an unsaturated aromatic ring containing multiple rings (preferably 1 to 4 rings) connected by covalent bonds. Non-limiting examples of aryl include phenyl, biphenyl, terphenyl, m-terphenyl, p-terphenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2 -Anthracene, 9-anthracenyl, 1-phenanthrenyl, 2-phenanthryl, 3-phenanthryl, 4-phenanthryl, 9-phenanthryl, 1-fluorenyl, 2-fluorenyl, and 4-fluorene Base etc.

In the present invention, a heteroaryl group refers to a functional group in which one or more carbon atoms in the aryl group defined above are substituted with non-carbon atoms, for example, nitrogen, oxygen, or sulfur.

Non-limiting examples of heteroaryl include furyl, tetrahydrofuranyl, pyrrolyl, pyrrolidinyl, thienyl, tetrahydrothienyl, and oxazolyl ), Isoxazolyl, triazolyl, thiazolyl, isothiazolyl, pyrazolyl, pyrazolidinyl, oxadiazolyl oxadiazolyl, thiadiazolyl, imidazolyl, imidazolinyl, pyridyl, pyridazinyl, triazinyl, piperidinyl , Morpholinyl, thiomorpholinyl, pyrazinyl, piperazinyl, pyrimidinyl, naphthyridinyl, benzofuranyl, phenylamidine Thienyl, indolyl, indolyl, indolazinyl, indazolyl, quinazinyl, quinolinyl, isoquinolinyl, cinnolinyl, phthalazinyl (phthalazinyl), quinazolinyl, quinoxaline, pteridinyl, quinuclidinyl, fluorene Group, acridinyl group, phenazine group, a phenothiazine group (phenothizinyl), phenazine group, purinyl, imidazolyl phenyl Bing (benzimidazolyl) benzene and the like, and Bing thiazolyl fused analogues of these.

In the present invention, as a functional group in a form in which the aryl group is substituted with the carbon of the alkyl group, the aralkyl group is a general term of-(CH ₂ ) _n Ar. Examples of the aralkyl group include benzoin (-CH ₂ C ₆ H ₅ ), phenethyl (-CH ₂ CH ₂ C ₆ H ₅ ), and the like.

In the present invention, unless a different definition is made, a cycloalkyl group or a heterocycloalkyl group containing a hetero atom may be understood as a cyclic structure of an alkyl group or a heteroalkyl group, respectively.

Non-limiting examples of cycloalkyl include cyclopentyl, cyclohexyl, 1-cyclohexenyl, 3-cyclohexenyl, and cycloheptyl.

Non-limiting examples of heteroalkyl-containing cycloalkyl groups are 1- (1,2,5,6-tetrahydropyridyl), 1-piperidinyl, 2-piperidinyl, 3-piperidinyl, 4 -Morpholinyl, 3-morpholinyl, tetrahydrofuran-2-yl, tetrahydrofuran-3-yl, tetrahydrothiophen-2-yl, tetrahydrothiophen-3-yl, 1-piperazinyl and 2-piperazinyl Wait.

Also, a cycloalkyl group or a cycloalkyl group containing a hetero atom may have a form bonded to a cycloalkyl group, a cycloalkyl group containing a hetero atom, a fused aryl group, or a heteroaryl group or connected by a covalent bond.

In the present invention, as the functional group in a form where the silyl group is substituted with oxygen, the siloxy group is a general term for -O-Si (R) ₃ .

Preferably, the first silane compound is present in the silicon nitride film etching solution at 100 ppm to 10000 ppm.

In the silicon nitride film etching solution, when the first silane compound is less than 100 ppm, the effect of increasing the selectivity of the silicon nitride film relative to the silicon oxide film may be imperfect. Conversely, when the first silane compound is larger than 10000 ppm in the silicon nitride film etching solution, as the silicon concentration in the silicon nitride film etching solution increases, the problem of a decrease in the etching rate of the silicon nitride film may occur. The first silane compound itself can act as a source of silicon-based particles.

According to an embodiment of the present invention, the silicon nitride film etching solution not only compensates for the etching speed of the silicon nitride film that is reduced by containing the first silane compound as a silicon additive, but also improves the efficiency of the entire etching process. Contains fluorinated compounds.

In the present invention, the fluorine-containing compound refers to a compound in any form in which all fluorine ions can be dissociated.

According to an embodiment, the fluorine-containing compound is at least one selected from hydrofluoric acid, ammonium fluoride, ammonium difluoride, and ammonium hydrogen fluoride.

Furthermore, according to another embodiment, the fluorine-containing compound may be a compound in a form in which an organic cation and a fluorine-based anion are combined.

For example, the fluorine-containing compound may be a compound in which an alkylammonium is bonded to a fluorine-based anion ion. Among them, alkyl ammonium, as an ammonium having at least one alkyl group, may have up to four alkyl groups. The definition of an alkyl group is as described above.

According to yet another embodiment, the fluorine-containing compound may be selected from the group consisting of alkylpyrrole, alkylimidazole, alkylpyrazole, alkyloxazole, alkylthiazole, alkylpyridine, alkylpyrimidine, alkylpyridine, and alkylpyridine. Organic cations in azine, alkylpyrrolidine, alkylphosphorus, alkylmorpholine and alkylpiperidine and selected from fluorophosphate, fluoroalkyl-fluorophosphate, fluoroborate and fluoroalkyl-fluoroborate An ionic liquid in which a fluorine-based anion is ion-bonded.

In the silicon nitride film etching solution, as a fluorine-containing compound, the fluorine-containing compound provided in the form of an ionic liquid has a higher boiling point and a decomposition temperature than a conventionally used hydrofluoric acid or ammonium fluoride. This has the advantage that in the etching step performed at a high temperature, there is little concern that the composition of the etching solution changes with decomposition.

However, as the silicon nitride film etching solution contains an excessive amount of fluorine-containing compounds, when excess fluorine or fluoride ions remain in the etching solution, not only can the etching rate of the silicon nitride film be increased, but also the silicon oxide film can be increased. The problem of the etching rate of the film.

Therefore, according to the present invention, the silicon nitride film etching solution additionally contains a second silane compound represented by the following Chemical Formula 3 or Chemical Formula 4, so that an increase in the etching rate of the silicon oxide film due to a fluorine-containing compound can be suppressed. The problem.

As shown in the following Chemical Formula 3, in the present invention, the second silane compound may be defined as a compound in which one silicon atom is combined with a functional group of R ₁₁ to R ₁₄ . Among them, one or two hydrophilic functional groups in R ₁₁ to R ₁₄ .

其中，R₁₁至R₁₄分別獨立地選自親水性官能團或氫、C₁-C₁₀烷基、C₆-C₁₂環烷基、包含至少一個雜原子的C₂-C₁₀雜烷基、C₂-C₁₀烯基、C₂-C₁₀炔基、C₁-C₁₀鹵代烷基、C₁-C₁₀氨基烷基、芳基、雜芳基、芳烷基、矽氧基及矽氧烷的官能團。

Wherein R ₁₁ to R ₁₄ are each independently selected from a hydrophilic functional group or hydrogen, a C ₁ -C ₁₀ alkyl group, a C ₆ -C ₁₂ cycloalkyl group, a C ₂ -C ₁₀ heteroalkyl group containing at least one hetero atom, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl, siloxy and siloxy Functional group.

And, as shown in the following Chemical Formula 4, in the present invention, the second silane compound may be defined as a silane compound continuously bonded to at least two silicon atoms.

其中，R₁₅至R₂₀分別獨立地選自親水性官能團或氫、C₁-C₁₀烷基、C₆-C₁₂環烷基、包含至少一個雜原子的C₂-C₁₀雜烷基、C₂-C₁₀烯基、C₂-C₁₀炔基、C₁-C₁₀鹵代烷基、C₁-C₁₀氨基烷基、芳基、雜芳基、芳烷基、矽氧基及矽氧烷的官能團，n為1至5的整數。

Wherein R ₁₅ to R ₂₀ are each independently selected from a hydrophilic functional group or hydrogen, a C ₁ -C ₁₀ alkyl group, a C ₆ -C ₁₂ cycloalkyl group, a C ₂ -C ₁₀ heteroalkyl group containing at least one hetero atom, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl, siloxy and siloxy Functional group of alkane, n is an integer of 1 to 5.

That is, the second silane compound contains one to six silicon atoms and contains a hydrophilic functional group bonded to the silicon atom, and thus has a form that can ensure an appropriate level of solubility in a silicon nitride film etching solution containing an acid-containing aqueous solution. .

Accordingly, the second silane compound existing in a state where it is appropriately dissolved in the silicon nitride film etching solution is appropriately developed with respect to the first silane compound and the fluorine-containing compound which is excessively present. This prevents the increase in the etching rate of the silicon oxide film.

In addition, the possibility that the second silane compound has a small number of hydrophilic functional groups relative to the first silane compound and functions as a core of the silicon-based particles can be minimized.

In particular, in order to ensure the solubility in the silicon nitride film etching solution, the second silane compound has at most two hydrophilic functional groups, and the second silane compound may have at most two silicon-hydroxyl groups under the pH condition of the acid aqueous solution. -Si-OH).

Among them, the second silane compound has at most two hydrophilic functional groups, which means that the number of hydrophilic functional groups bound to one silicon atom is two at most. In addition, in order to ensure the solubility in the silicon nitride film etching solution, it is preferable that the second silane compound has at least one hydrophilic functional group.

In addition, when there is only one silicon atom constituting the second silane compound, among the four functional groups bonded to the silicon atom, the hydrophilic functional group is one or two. And, preferably, when there are two or more silicon atoms constituting the second silane compound, at least one silicon atom combined with at least one and at least two hydrophilic functional groups is included.

Here, when the hydrophilic functional group in the second silane compound is replaced by a silicon-hydroxy group (-Si-OH) under the pH condition of the acidic aqueous solution, the second silane compound and the silicon hydroxy group (-Si-OH) and The first silane compound or the second silane compound is polymerized to grow into a silicon dimer, a silicon oligomer, or a silicone oil having a regular mono- or binary arrangement, thereby preventing the generation of silicon-based particles due to random growth in advance.

Preferably, in the silicon nitride film etching solution, the second silane compound is present at 100 ppm to 30,000 ppm.

When the second silane compound in the silicon nitride film etching solution is less than 100 ppm, Not only is it difficult to suppress the etching of the silicon oxide film due to the excessive presence of fluorine-containing compounds, but it is also difficult to suppress the generation of silicon-based particles due to the first silane compound.

As described above, the silicon nitride film etching solution of the present invention has the advantage that it can maintain a high selection ratio of the silicon nitride film relative to the silicon oxide film, and at the same time can be controlled during etching or cleaning after etching. , The generation of silicon particles.

Therefore, when the silicon nitride film etching solution of the present invention etches the silicon nitride film at a temperature of 165 ° C. for 1 minute, the average diameter of the silicon-based particles generated may be 0.1 μm or less.

According to another embodiment of the present invention, a post-etch cleaning solution is provided. After the silicon substrate (wafer) is etched with an etching solution containing a silicon additive, the generation of silicon-based particles can be reduced or controlled during cleaning.

More specifically, the post-etching cleaning solution according to the embodiment of the present invention may include an aqueous solution of an acid and a second silane compound as shown in Chemical Formula 3 or Chemical Formula 4. Among them, unless different definitions are made, the definitions of the acid aqueous solution and the second silane compound are as defined in the silicon nitride film etching solution.

Among them, the aqueous acid solution is a component that not only removes nano-sized silicon-based particles generated during etching, but also maintains the pH of the cleaning solution to suppress the silane compound present in the cleaning solution from becoming silicon-based particles.

In addition, after the etching of the silicon substrate with an etching solution containing a silicon additive in an aqueous acid solution, the acid in the aqueous acid solution serves to dissolve various pollution sources (including nano-sized silicon-based particles) existing on the silicon substrate or clean the silicon substrate. The role of dispersion in the cleaning solution. Accordingly, after performing primary cleaning of the silicon substrate using the cleaning solution, and when performing secondary cleaning using deionized water or the like, various sources of pollution can be easily removed from the silicon substrate.

According to an embodiment, preferably, the aqueous solution contains 60 to 95 parts by weight of the acid relative to 100 parts by weight of the cleaning solution.

When the content of the aqueous acid solution is less than 60 parts by weight relative to 100 parts by weight of the cleaning solution, silicon-based particles are generated from the silicon-based additive used in the etching solution remaining on the silicon substrate after etching due to the increase in the pH of the cleaning solution. Therefore, there is a concern that the efficiency of the cleaning process can be reduced.

On the contrary, when the content of the aqueous acid solution is more than 95 parts by weight relative to 100 parts by weight of the cleaning solution, the viscosity of the aqueous acid solution is too high, and there is a concern that the fluidity of the cleaning solution may be reduced. When the fluidity of the acid aqueous solution is decreased, the efficiency of the cleaning process may be reduced or the surface of the silicon substrate may be damaged. For example, the surface damage of a silicon substrate includes pattern defects caused by etching of a silicon oxide film.

And, preferably, the content of water in the acid aqueous solution is 40% by weight or less, and particularly, it is preferably in the range of 5 to 15% by weight.

When the content of water in the aqueous acid solution is more than 40% by weight, there is a concern that silicon-based particles are generated from a silicon-based additive used in an etching solution remaining on a silicon substrate after etching due to an increase in the pH of the cleaning solution. On the contrary, when the content of water in the acid aqueous solution is less than 5 weight percent, not only the fluidity of the cleaning solution may be reduced, but also there may be a concern that the final silicon substrate is over-etched due to the etching of the silicon substrate by the cleaning solution.

Moreover, it is preferable that the pH of the aqueous solution of the acid containing an inorganic acid and / or an organic acid is 4 or less.

When the pH of the aqueous acid solution is greater than 4, there may be a concern that silicon-based particles may be generated from a silicon additive for an etching solution remaining on a silicon substrate due to excessive water and high pH contained in the cleaning solution.

By the form in which the second silane compound represented by Chemical Formula 3 or Chemical Formula 4 combines one silicon atom with at least one and at least two hydrophilic functional groups, the solubility in a cleaning solution containing an acid-containing aqueous solution can be sufficiently ensured.

In addition, since the second silane compound represented by Chemical Formula 3 or Chemical Formula 4 has at most two hydrophilic functional groups, it is unlikely that the silane compound itself functions as a source of silicon-based particles during cleaning.

At the pH of an acidic aqueous solution, a silicon compound having a maximum of two silicon-hydroxy (-Si-OH) second silane compounds and a plurality of nanometer-sized silicon-based particles present on a silicon substrate after the etching- Hydroxyl (-Si-OH) polymerizes to produce a silicon-siloxane compound.

At this time, unlike the second silane compound represented by the above Chemical Formula 3 or Chemical Formula 4, when the number of the hydrophilic functional groups bonded to the silicon atom constituting the silane compound is 3 or more (for example, the first silane compound), In the case where a silane compound having a silicon-hydroxyl group is polymerized with a plurality of nano-sized silicon-based particles, random growth can be formed due to the relatively large number of polymerizable functional groups. As a result, there may be a concern that micron-sized silicon-based particles are generated.

Therefore, as shown in Chemical Formula 3 or Chemical Formula 4, when the second silane compound used in the cleaning solution of various embodiments of the present invention is cleaned after the etching of the silicon substrate, it will interact with the silicon particles present in the cleaning solution. The bonded hydroxyl group is replaced with a siloxane that is no longer polymerizable. This prevents the silicon-based particles from growing and precipitating in a micron size.

Among them, preferably, the cleaning solution contains 100 ppm to 5000 ppm of the second silane compound.

When the second silane compound in the cleaning solution is less than 100 ppm, after the silicon substrate is etched with an etching solution containing a silicon additive, the nanometer size is suppressed in the cleaning process performed. The effect of small silicon particles growing to micron size may be insufficient.

On the contrary, when the second silane compound in the cleaning solution is more than 5000 ppm, there is a problem that the silane compound is difficult to be sufficiently dissolved in the cleaning solution.

As described above, after a silicon substrate is etched with an etching solution containing a silicon additive, the silane compound present in the cleaning solution can suppress the mechanism of the growth of silicon-based particles during cleaning. In addition, the use of the cleaning solution of the present invention can prevent the growth and precipitation of silicon-based particles during cleaning of the silicon substrate after etching.

As a result, silicon substrate and / or equipment defects caused by silicon-based particles can be reduced in the end.

In addition, by using the cleaning solution of the present invention, even if an etching solution containing a silicon additive is used to etch a silicon substrate, the generation of silicon-based particles can be reduced or suppressed during cleaning, and the composition of the etching solution can be more easily designed. That is, there is no need to use other expensive additives as a substitute for the silicon additive.

According to another embodiment of the present invention, after a silicon substrate is etched with an etching solution containing a silicon additive, a method for cleaning the substrate after etching can reduce or suppress generation of silicon-based particles during cleaning.

More specifically, the method for cleaning an etched substrate according to an embodiment of the present invention includes: a step of once cleaning a substrate with a cleaning solution etched by an etching solution containing a silicon additive; and a second cleaning of the substrate subjected to the first cleaning with water. step.

The substrate cleaning method of the embodiment of the present invention is based on the premise that the silicon substrate is etched with an etching solution containing a silicon additive.

According to the present invention, the etched substrate is cleaned once with an aqueous solution of an acid containing a second silane compound, thereby replacing the silicon-hydroxy group with a siloxane that cannot be repolymerized, which can prevent silicon-based particles from growing and precipitating in micron sizes .

Among them, preferably, when the etched substrate is cleaned once, the temperature of the cleaning solution is 70 ° C to 160 ° C.

Generally, the temperature of the etching solution used for etching is 150 ° C or higher. Therefore, when the temperature of the cleaning solution is less than 70 ° C during one cleaning, the silicon substrate may be damaged due to a rapid temperature change of the silicon substrate. In addition, when the temperature of the cleaning solution is greater than 160 ° C during one cleaning, the silicon substrate may be damaged due to excessive heat.

Then, a plurality of sources of contamination are removed from the silicon substrate according to a second cleaning of the substrate that is once cleaned with water (for example, deionized water).

Among them, preferably, the temperature of the water during the second cleaning of the substrate cleaned once is 25 ° C to 80 ° C.

Hereinafter, specific examples of the present invention will be described. However, a plurality of examples described below are only for specifically exemplifying or explaining the present invention, and the present invention should not be limited thereto.

Experimental Example 1: Silicon Nitride Film Etching Solution

Examples

In Table 1 below, the composition of the silicon nitride film etching solution of the example is shown.

The silicon nitride film etching solution according to Examples 1 to 8 contains 85 weight percent phosphoric acid and the remaining water. The first silane compound, the second silane compound, and the fluorine-containing compound described in Table 1 are included in ppm units.

In Example 1, tetrahydroxysilane was used as the first silane compound, trimethylhydroxysilane was used as the second silane compound, and hydrofluoric acid was used as the fluorine-containing compound.

In Example 2, tetrahydroxysilane was used as the first silane compound, trimethylhydroxysilane was used as the second silane compound, and ammonium hydrogen fluoride was used as the fluorine-containing compound.

In Example 3, tetrahydroxysilane was used as the first silane compound, chlorotrimethylsilane was used as the second silane compound, and ammonium fluoride was used as the fluorine-containing compound.

In Example 4, 3-aminopropyltrihydroxysilane was used as the first silane compound, dichlorodimethylsilane was used as the second silane compound, and ammonium fluoride was used as the fluorine-containing compound.

In Example 5, hexahydroxydisilazane was used as the first silane compound, 1,3-disilazanediol was used as the second silane compound, and ammonium fluoride was used as the fluorine-containing compound. .

In Example 6, trimethoxyhydroxysilane was used as the first silane compound, trimethylhydroxysilane was used as the second silane compound, and hydrofluoric acid was used as the fluorine-containing compound.

In Example 7, as the first silane compound, butyltrihydroxysilicon was used. As the second silane compound, trimethylhydroxysilane was used, and as the fluorine-containing compound, hydrofluoric acid was used.

In Example 8, tetrahydroxysilane was used as the first silane compound, chlorotrimethylsilane was used as the second silane compound, and hydrofluoric acid was used as the fluorine-containing compound.

Comparative example

In Table 2 below, the composition of the silicon nitride film etching solution according to the comparative example is shown.

The silicon nitride film etching solutions according to Comparative Examples 1 to 4 contained 85 weight percent phosphoric acid and the remaining water, and the first silane compound and fluorine-containing compound described in Table 1 were included in ppm units.

In Comparative Example 1, tetrahydroxysilane was used as the first silane compound, and hydrofluoric acid was used as the fluorine-containing compound.

In Comparative Example 2, tetrahydroxysilane was used as the first silane compound, and ammonium hydrogen fluoride was used as the fluorine-containing compound.

In Comparative Example 3, tetrahydroxysilane was used as the first silane compound, chlorotrimethylsilane was used as the second silane compound, and fluorine was used as the fluorine-containing compound. Of ammonium.

In Comparative Example 4, 3-aminopropyltrihydroxysilane was used as the first silane compound, and ammonium fluoride was used as the fluorine-containing compound.

Experimental results

The silicon nitride film etching solution having the composition of each example and comparative example was used, and the silicon nitride film and the silicon nitride film were heated at each temperature (145 ° C, 157 ° C, 165 ° C) for 0.5 hours, 1 hour, and 2 hours. The silicon oxide film was etched for 1 minute. The silicon oxide film is an oxide film grown by heat, and shows an etching rate of 2 Å / min in a pure phosphoric acid solution at 165 ° C.

Before putting the etching solution, the silicon nitride film and the silicon oxide film were subjected to a planarization operation. The planarization operation diluted 50% by weight of hydrofluoric acid to 200: 1 into hydrofluoric acid, and then diluted the hydrofluoric acid in The immersion was performed for 30 seconds.

After the etching at each etching temperature and each etching time is completed, the etching solution is analyzed with a particle size analyzer to measure the average diameter of the silicon-based particles present in the etching solution.

The etching rate was 165 ° C. After 5 minutes of etching, the average etching amount per minute was calculated with an ellipsometer.

The measurement results are shown in Tables 3 to 14 below.

Table 4

As a result of performing particle size analysis on the silicon nitride film etching solution having the composition of Examples 1 to 8, it was confirmed that silicon-based particles were not present in the etching solution or that the diameter thereof was particularly fine 0.01 μm or less.

In particular, it was confirmed that even if the silicon nitride film etching solution is heated at a high temperature for a long time, silicon-based particles are hardly generated.

In addition, as a result of measuring the etching amount per minute at 165 ° C., it was confirmed that the etching rate similar to that of pure phosphoric acid was shown even when a fluorine-containing compound was added to the etching solution.

In contrast, the particle size analysis results of the silicon nitride film etching solutions having the compositions of Comparative Examples 1 to 4 were confirmed. In silicon-based particles having a diameter of 20 μm or more.

In addition, it was confirmed that the etching amount per minute of the silicon oxide film was increased by the fluorine-containing compound.

Experimental example 2: cleaning solution after etching

Experimental result 1

Before putting a silicon substrate containing a silicon nitride film into an etching solution, 50% by weight of hydrofluoric acid was immersed in a solution that was diluted by 200: 1 for 30 seconds to perform a planarization operation.

Then, the planarized silicon substrate was etched with an 80% phosphoric acid aqueous solution containing 500 ppm of tetrahydroxysilane and 500 ppm of ammonium fluoride (NH4F) for 5 minutes, and then cleaned at 80 ° C. having the composition of each example and comparative example. After the solution was washed once for 10 seconds, it was washed twice with deionized water at 80 ° C for 30 seconds.

The cleaning solution after the first cleaning and the deionized water after the second cleaning are separately extracted, and the average diameter of the silicon-based particles in the cleaning solution and the deionized water is measured by a particle size analyzer.

Table 15 below shows the measurement results of the composition of the cleaning solutions of Example 9 and Example 10 and Comparative Examples 5 to 7 and the average diameters of the silicon-based particles present in the cleaning solution after cleaning and the deionized water.

Experimental result 2

Before putting a silicon substrate containing a silicon nitride film into an etching solution, 50% by weight of hydrofluoric acid was immersed in a solution that was diluted by 200: 1 for 30 seconds to perform a planarization operation.

Then, the planarized silicon substrate was etched with an 80% phosphoric acid aqueous solution containing 500 ppm of 3-aminopropylsilantriol and 500 ppm of ammonium fluoride for 5 minutes, and then the respective examples and comparative examples were used. The composition was cleaned at 80 ° C for 10 seconds, and then washed twice with deionized water at 80 ° C for 30 seconds.

The cleaning solution after the first cleaning and the deionized water after the second cleaning are separately extracted, and the average diameter of the silicon-based particles in the cleaning solution and the deionized water is measured by a particle size analyzer.

Table 16 below shows the composition of the cleaning solutions of Examples 11 to 13 and Comparative Examples 8 to 10, the measurement results of the average diameters of the silicon-based particles present in the cleaning solution after cleaning, and the deionized water.

Experimental result 3

Before putting a silicon substrate containing a silicon nitride film into an etching solution, 50% by weight of hydrofluoric acid was immersed in a solution that was diluted by 200: 1 for 30 seconds to perform a planarization operation.

Then, the planarized silicon substrate was etched with an 80% phosphoric acid aqueous solution containing 500 ppm of 3-aminopropylsilanetriol and 500 ppm of ammonium fluoride for 5 minutes, and then 80 ° C. having a composition of each example and comparative example was used. After performing a primary cleaning for 10 seconds, the secondary cleaning was performed for 30 seconds with deionized water at 80 ° C.

The cleaning solution after the first cleaning and the deionized water after the second cleaning are separately extracted, and the average diameter of the silicon-based particles in the cleaning solution and the deionized water is measured by a particle size analyzer.

Table 17 below shows the composition of the cleaning solutions of Example 14 and Comparative Example 11, the measurement results of the average diameter of the silicon-based particles present in the cleaning solution after the cleaning, and the deionized water. fruit.

Experimental result 4

Before putting a silicon substrate containing a silicon nitride film into an etching solution, 50% by weight of hydrofluoric acid was immersed in a solution that was diluted by 200: 1 for 30 seconds to perform a planarization operation.

Then, the planarized silicon substrate was etched with an 80% phosphoric acid aqueous solution containing 500 ppm of tetrahydroxysilane and 500 ppm of ammonium fluoride for 5 minutes, and then a cleaning solution at 80 ° C. having a composition of each example and comparative example was used. After the primary washing for 10 seconds, the secondary washing was performed for 30 seconds with deionized water at 80 ° C.

The cleaning solution after the first cleaning and the deionized water after the second cleaning are separately extracted, and the average diameter of the silicon-based particles in the cleaning solution and the deionized water is measured by a particle size analyzer.

Table 18 below shows the measurement results of the composition of the cleaning solution of Example 15 and Example 16 and Comparative Example 12, the average diameter of the silicon-based particles present in the cleaning solution after the cleaning, and the deionized water.

Experimental result 5

Before putting a silicon substrate containing a silicon nitride film into an etching solution, 50% by weight of hydrofluoric acid was immersed in a solution that was diluted by 200: 1 for 30 seconds to perform a planarization operation.

Then, the flattened silicon substrate was etched with 500 ppm of tetrahydroxysilane and 500 ppm of an 80% phosphoric acid aqueous solution of ammonium fluoride for 5 minutes, and then the cleaning solution was used at various temperatures having the composition of each example and comparative example. After a 10-second wash, a second wash was performed for 30 seconds with deionized water at various temperatures.

The cleaning solution after the first cleaning and the deionized water after the second cleaning are separately extracted, and the average diameter of the silicon-based particles in the cleaning solution and the deionized water is measured by a particle size analyzer.

Table 19 below shows the measurement results of the composition of the cleaning solutions of Example 17 and Example 18, Comparative Example 13 and Comparative Example 14, the cleaning solution after cleaning, and the average diameter of the silicon-based particles present in the deionized water.

As mentioned above, an embodiment of the present invention has been described. As long as a person of ordinary skill in the technical field to which the present invention pertains may not exceed the gist of the present invention described in the scope of protection of the invention, with the addition, modification, Various modifications and changes to the present invention such as deletion or addition are also included in the scope of patent application of the present invention.

Claims (15)

A silicon nitride film etching solution includes: an aqueous solution containing at least one of an inorganic acid and an organic acid; a first silane compound containing 1 to 6 silicon atoms, and a combination with more than three hydrophilic functional groups At least one silicon atom; a second silane compound containing 1 to 6 silicon atoms; the number of hydrophilic functional groups combined with one silicon atom is at most two; and a fluorine-containing compound. The silicon nitride film etching solution according to claim 1, wherein the inorganic acid is selected from the group consisting of sulfuric acid, nitric acid, phosphoric acid, silicic acid, hydrofluoric acid, boric acid, hydrochloric acid, perchloric acid, anhydrous phosphoric acid, pyrophosphoric acid, and polymer. At least one of phosphoric acid. The silicon nitride film etching solution according to claim 1, wherein the organic acid is at least one selected from the group consisting of acetic acid, citric acid, formic acid, gluconic acid, lactic acid, oxalic acid, tartaric acid, and bicarbonate. The silicon nitride film etching solution according to claim 1, wherein the hydrophilic functional group is a functional group capable of being substituted by a hydroxyl group or under a pH condition of the silicon nitride film etching solution. The silicon nitride film etching solution according to claim 4, wherein the functional group capable of being substituted by a hydroxyl group under the pH condition of the silicon nitride film etching solution is selected from the group consisting of an amino group, a halogen group, a sulfonic acid group, a phosphonic acid group, and a phosphoric acid group. , Thiol group, alkoxy group, amido group, ester group, acid anhydride group, fluorenyl halide group, cyano group, carboxyl group and azole group. The silicon nitride film etching solution according to claim 1, wherein the first silane compound is a silicon nitride film etching solution represented by the following Chemical Formula 1 or Chemical Formula 2: [Chemical Formula 1]

Wherein R ₁ to R ₄ are each independently selected from a hydrophilic functional group or hydrogen, a C ₁ -C ₁₀ alkyl group, a C ₆ -C ₁₂ cycloalkyl group, a C ₂ -C ₁₀ heteroalkyl group containing at least one hetero atom, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl, siloxy and siloxy Functional groups in alkanes;

Wherein R ₅ to R ₁₀ are each independently selected from a hydrophilic functional group or hydrogen, a C ₁ -C ₁₀ alkyl group, a C ₆ -C ₁₂ cycloalkyl group, a C ₂ -C ₁₀ heteroalkyl group containing at least one hetero atom, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl, siloxy and siloxy The functional group in the alkane, n is an integer of 1 to 5. The silicon nitride film etching solution according to claim 6, wherein the hydrophilic functional group is selected from the group consisting of a hydroxyl group, an amino group, a halogen group, a sulfonic acid group, a phosphonic acid group, a phosphoric acid group, a thiol group, an alkoxy group, and a fluorenyl group. , Ester group, acid anhydride group, fluorenyl halide group, cyano group, carboxyl group and azole group. The silicon nitride film etching solution according to claim 1, wherein the silicon nitride film etching solution comprises 100 ppm to 10000 ppm of the first silane compound. The silicon nitride film etching solution according to claim 1, wherein the second silane compound is a silicon nitride film etching solution represented by the following Chemical Formulas 3 and 4:

R ₁₁ to R ₁₄ are each independently selected from hydrophilic functional groups or hydrogen, C ₁ -C ₁₀ alkyl, C ₆ -C ₁₂ cycloalkyl, C ₂ -C ₁₀ heteroalkyl containing at least one heteroatom, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl, siloxy, and siloxane Functional group

R ₁₅ to R ₂₀ are each independently selected from hydrophilic functional groups or hydrogen, C ₁ -C ₁₀ alkyl, C ₆ -C ₁₂ cycloalkyl, C ₂ -C ₁₀ heteroalkyl containing at least one hetero atom, C ₂ -C ₁₀ alkenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl, siloxy and siloxane In the functional group, n is an integer of 1 to 5. The silicon nitride film etching solution according to claim 9, wherein the hydrophilic functional group is selected from the group consisting of a hydroxyl group, an amino group, a halogen group, a sulfonic acid group, a phosphonic acid group, a phosphoric acid group, a thiol group, an alkoxy group, and an amido group. , Ester group, acid anhydride group, fluorenyl halide group, cyano group, carboxyl group and azole group. The silicon nitride film etching solution according to claim 1, wherein the silicon nitride film etching solution comprises 100 ppm to 30,000 ppm of the second silane compound. The silicon nitride film etching solution according to claim 1, wherein the fluorine-containing compound is selected from the group consisting of fluorinated At least one of hydrogen, ammonium fluoride, ammonium difluoride, and ammonium bifluoride. The silicon nitride film etching solution according to claim 1, wherein the fluorine-containing compound is a compound having a form in which organic cations and fluorine-based anions are ion-bonded. The silicon nitride film etching solution according to claim 13, wherein the organic cation is selected from the group consisting of alkylammonium, alkylpyrrole, alkylimidazole, alkylpyrazole, alkyloxazole, alkylthiazole, alkylpyridine, Alkylpyrimidine, alkylpyridazine, alkylpyrazine, alkylpyrrolidine, alkylphosphorus, alkylmorpholine and alkylpiperidine. The silicon nitride film etching solution according to claim 13, wherein the fluorine-based anion is selected from the group consisting of fluoride, fluorophosphate, fluoroalkyl-fluorophosphate, fluoroborate, and fluoroalkyl-fluoroborate.