KR102546609B1 - Etching solution for silicon substrate - Google Patents

Abstract

The present invention relates to a silicon substrate etching solution, and more particularly, to a silicon substrate etching solution capable of suppressing generation of silicon-based particles during etching of a silicon nitride film.

Description

Silicon substrate etching solution {ETCHING SOLUTION FOR SILICON SUBSTRATE}

The present invention relates to a silicon substrate etching solution, and more particularly, to a silicon substrate etching solution capable of suppressing generation of silicon-based particles during etching of a silicon nitride film.

Currently, there are various methods of etching the silicon nitride film and the silicon oxide film, but dry etching and wet etching are the most commonly used methods.

The dry etching method is an etching method using a gas and has the advantage of being superior to the wet etching method in isotropy, but the wet etching method is widely used in that the productivity is much lower than the wet etching method and is expensive.

In general, as a wet etching method, a method using phosphoric acid as an etching solution is well known. At this time, when only pure phosphoric acid is used to etch the silicon nitride film, as the device is miniaturized, not only the silicon nitride film but also the silicon oxide film is etched, which may cause problems such as occurrence of various defects and pattern abnormalities. need to be further lowered.

Accordingly, recently, a silicon additive is used along with phosphoric acid to increase the etching rate of the silicon nitride layer and lower the etching rate of the silicon oxide layer.

An object of the present invention is to provide a silicon substrate etching solution capable of suppressing the generation of silicon-based particles in the silicon etching solution.

In order to solve the above-described technical problem, according to one aspect of the present invention, an inorganic acid aqueous solution, a silicon additive represented by Formula 1 or Formula 2 below, and an imidazolium phosphate represented by Formula 3 below are used to etch a silicon substrate. solution is provided.

[Formula 1]

[Formula 2]

[Formula 3]

Here, R ₁ to R ₄ are each independently 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 Al kenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl and hydroxy, amino, halogen, sulfone, phosphonic, phosphoric, cy is a functional group selected from ol, alkoxy, amide, ester, acid anhydride, acyl halide, cyano, carboxyl and azole, and R ₅ to R ₁₀ are each independently hydrogen, C ₁ -C ₁₀ alkyl, C ₆ -C ₁₂ cyclo alkyl, 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 and a functional group selected from hydroxy, amino, halogen, sulfone, phosphonic, phosphoric, thiol, alkoxy, amide, ester, acid anhydride, acyl halide, cyano, carboxyl and azole; n is an integer of 1 to 5, R ₁₁ to R ₁₄ are each independently 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 and aralkyl.

According to the present invention, it is possible to suppress generation of silicon-based particles during storage of the etching solution or etching using the etching solution due to an electrostatic interaction between the imidazolium phosphate and the silicon additive in the silicon substrate etching solution.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the following examples. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various forms different from each other, only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention pertains. It is provided to completely inform the person who has the scope of the invention, and the present invention is only defined by the scope of the claims.

Hereinafter, a silicon substrate etching solution according to the present invention will be described in detail.

According to one aspect of the present invention, a silicon substrate etching solution containing an aqueous inorganic acid solution and a silicon additive is provided.

The silicon substrate to be etched by the silicon substrate etching solution according to the present invention preferably includes at least a silicon oxide film (SiO _x ), and includes a silicon oxide film and a silicon nitride film (Si _x N _y , SI _x O _y N _z ) at the same time. can also. In the case of a silicon substrate including a silicon oxide layer and a silicon nitride layer, the silicon oxide layer and the silicon nitride layer may be alternately stacked or stacked in different regions.

Here, the silicon oxide film is a SOD (Spin On Dielectric) film, HDP (High Density Plasma) film, thermal oxide film, BPSG (Borophosphate Silicate Glass) film, PSG (Phospho Silicate Glass) film depending on the use and material type. , BSG (Boro Silicate Glass) film, PSZ (Polysilazane) film, FSG (Fluorinated Silicate Glass) film, LP-TEOS (Low Pressure Tetra Ethyl Ortho Silicate) film, PETEOS (Plasma Enhanced Tetra Ethyl Ortho Silicate) film, HTO (High Temperature Oxide) film, MTO (Medium Temperature Oxide) film, USG (Undopped Silicate Glass) film, SOG (Spin On Glass) film, APL (Advanced Planarization Layer) film, ALD (Atomic Layer Deposition) film, PE-oxide film (Plasma Enhanced oxide) or O ₃ -TEOS (O ₃ -Tetra Ethyl Ortho Silicate).

Here, the inorganic acid aqueous solution may be an aqueous solution containing at least one inorganic acid selected from sulfuric acid, nitric acid, phosphoric acid, silicic acid, hydrofluoric acid, boric acid, hydrochloric acid, and perchloric acid. In addition, phosphoric anhydride, pyrophosphoric acid, or polyphosphoric acid may be used other than the above-mentioned inorganic acids.

The inorganic acid aqueous solution is a component that maintains the pH of the etching solution and suppresses the transformation of various types of silane compounds present in the etching solution into silicon-based particles.

In one embodiment, the inorganic acid aqueous solution is preferably included in an amount of 60 to 90 parts by weight based on 100 parts by weight of the silicon substrate etching solution.

If the content of the inorganic acid solution is less than 60 parts by weight with respect to 100 parts by weight of the silicon substrate etching solution, the etching rate of the silicon nitride film is lowered so that the silicon nitride film is not sufficiently etched or the silicon nitride film etching process efficiency is reduced. There is a concern.

On the other hand, when the content of the aqueous inorganic acid solution exceeds 90 parts by weight with respect to 100 parts by weight of the silicon substrate etching solution, the etching rate of the silicon nitride film excessively increases and even the silicon oxide film is etched quickly. The selectivity may be lowered, and defects of the silicon substrate may be caused due to etching of the silicon oxide film.

A silicon substrate etching solution according to an embodiment of the present invention may include a silicon additive represented by Formula 1 or Formula 2 below to increase a selectivity of a silicon nitride film to a silicon oxide film.

[Formula 1]

Here, R ₁ to R ₄ are each independently a hydrophilic functional group, 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, silyloxy and siloxane.

At this time, in order to suppress the growth of silicon-based particles from the silicone additive by the electrostatic interaction between the silicone additive represented by chemical room 1 and imidazolium phosphate to be described later, at least one of R ₁ to R ₄ is a polar functional group. desirable. Here, the polar functional group that at least one of R ₁ to R ₄ may have refers to a functional group having polarity among the above functional groups, and includes heteroalkyl, haloalkyl, aminoalkyl, and heteroaryl including a hydrophilic functional group or a hetero atom. , silyloxy and siloxanes, and the like.

The partial negative charge (δ ^- ) represented by the polar functional group of the silicone additive can be hindered by electrostatic interaction with the positive charge represented by the nitrogen atom of the imidazolium moiety of imidazolium phosphate. Accordingly, it is possible to suppress the growth of silicon-based particles by suppressing the formation of Si-O-Si bonds of the silicon additive.

In addition, as represented by Formula 2 below, the silicone additive herein may be defined as a silane compound in which at least two silicon atoms are continuously bonded.

[Formula 2]

Here, R ₅ to R ₁₀ are each independently a hydrophilic functional group, 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, silyloxy and a functional group selected from siloxane, n is It is an integer from 1 to 5.

At this time, in order to suppress the growth of silicon-based particles from the silicone additive by the electrostatic interaction between the silicone additive represented by chemical room 2 and imidazolium phosphate to be described later, at least one of R ₅ to R ₁₀ is a polar functional group. desirable. Here, the polar functional group that at least one of R ₅ to R ₁₀ may have refers to a functional group having polarity among the above functional groups, and includes heteroalkyl, haloalkyl, aminoalkyl, and heteroaryl including a hydrophilic functional group or a hetero atom. , silyloxy and siloxanes, and the like.

The partial negative charge (δ ^- ) represented by the polar functional group of the silicone additive can be hindered by electrostatic interaction with the positive charge represented by the nitrogen atom of the imidazolium moiety of imidazolium phosphate. Accordingly, it is possible to suppress the growth of silicon-based particles by suppressing the formation of Si-O-Si bonds of the silicon additive.

The hydrophilic functional group bonded to the silicon atom means a hydroxyl group or a functional group that can be substituted with a hydroxyl group under the pH condition of an inorganic acid aqueous solution.

Here, non-limiting examples of the functional group that can be substituted with a hydroxyl group under the pH condition of the inorganic acid aqueous solution include an amino group, a halogen group, a sulfonic group, a phosphonic group, a phosphoric group, a thiol group, an alkoxy group, an amide group, an ester group, and an acid anhydride. group, an acyl halide group, a cyano group, a carboxyl group, and an azole group, and it is not necessarily limited to the above-mentioned functional group, and it should be understood that it includes any functional group substitutable with a hydroxyl group under the pH condition of an aqueous inorganic acid solution.

In addition, the silicon substrate etching solution according to another embodiment of the present invention may include a silicon additive represented by Chemical Formula 1 and a silicon additive represented by Chemical Formula 2 at the same time.

Halogen herein means fluoro (-F), chloro (-Cl), bromo (-Br) or iodo (-I), and haloalkyl means an alkyl substituted with the aforementioned halogen. For example, halomethyl means methyl in which at least one of the hydrogens of methyl is replaced with a halogen (-CH ₂ X, -CHX ₂ or -CX ₃ ).

In addition, alkoxy here refers to both an -O-(alkyl) group and an -O-(unsubstituted cycloalkyl) group, and is a straight-chain or branched hydrocarbon having at least one ether group and 1 to 10 carbon atoms.

Specifically, methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, tert-butoxy, sec-butoxy, n-pentoxy, n-hexoxy, 1,2-dimethylbutoxy, cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, and the like.

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

A C _a -C _b functional group herein means a functional group having a to b carbon atoms. For example, C _a -C _b alkyl refers to a saturated aliphatic group having from a to b carbon atoms, including straight chain alkyl and branched alkyl and the like. A straight chain or branched alkyl has no more than 10 (eg C ₁ -C ₁₀ straight chain, C ₃ -C ₁₀ branched), preferably no more than 4, more preferably no more than 3 carbon atoms in its main chain. have

Specifically, alkyl is methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, i-butyl, t-butyl, pent-1-yl, pent-2-yl, pent-3-yl , 3-methylbut-1-yl, 3-methylbut-2-yl, 2-methylbut-2-yl, 2,2,2-trimethyleth-1-yl, n-hexyl, n-heptyl and n -may be octyl.

As used herein, unless otherwise defined, aryl refers to an unsaturated aromatic ring comprising a single ring or multiple rings (preferably 1 to 4 rings) linked to each other by conjugated or covalent bonds. Non-limiting examples of aryl include phenyl, biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2- Anthryl, 9-anthryl, 1-phenanthrenyl, 2-phenanthrenyl, 3-phenanthrenyl, 4--phenanthrenyl, 9-phenanthrenyl, 1-pyrenyl, 2- pyrenyl and 4-pyrenyl; and the like.

As used herein, heteroaryl refers to a functional group in which one or more carbon atoms in the aryl defined above are substituted with a non-carbon atom such as nitrogen, oxygen or sulfur.

Non-limiting examples of heteroaryl include furyl, tetrahydrofuryl, pyrrolyl, pyrrolidinyl, thienyl, tetrahydrothienyl, oxazolyl , isoxazolyl, triazolyl, thiazolyl, isothiazolyl, pyrazolyl, pyrazolidinyl, oxadiazolyl, thiadiazolyl (thiadiazolyl), imidazolyl, imidazolinyl, pyridyl, pyridaziyl, triazinyl, piperidinyl, morpholinyl ), thiomorpholinyl, pyrazinyl, piperainyl, pyrimidinyl, naphthyridinyl, benzofuranyl, benzothienyl, indolyl , indolinyl, indolizinil, indazolyl, quinolinyl, quinolinyl, isoquinolinyl, cinolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, teridinyl, quinuclidinyl, carbazolyl, acridinyl, phenazinyl, phenothizinyl, phenoxazinyl, purinyl, benzimidazolyl and benzothiazolyl; and the like; There are conjugated analogues.

In the present application, aralkyl is a functional group in which aryl is substituted on the carbon of alkyl, and is a general term for -(CH ₂ ) _n Ar. Examples of aralkyl include benzyl (-CH ₂ C ₆ H ₅ ) or phenethyl (-CH ₂ CH ₂ C ₆ H ₅ ).

Cycloalkyl (cycloalkyl) or cycloalkyl containing a heteroatom (heterocycloalkyl) herein will be understood as a cyclic structure of alkyl or heteroalkyl, respectively, unless otherwise defined.

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

Non-limiting examples of cycloalkyls containing heteroatoms include 1-(1,2,5,6-tetrahydropyridyl), 1-piperidinyl, 2-piperidinyl, 3-piperidinyl, 4- Morpholinil, 3-morpholinyl, tetrahydrofuran-2-yl, tetrahydrofuran-3-yl, tetrahydrothien-2-yl, tetrahydrothien-3-yl, 1-piperazinyl and 2 - Piperazinil, etc.

In addition, cycloalkyl or cycloalkyl containing a hetero atom may have a form in which a cycloalkyl, a cycloalkyl containing a hetero atom, an aryl, or a hetero aryl are conjugated or covalently bonded thereto.

The aforementioned silicon additive is preferably present in an amount of 100 to 10,000 ppm in the silicon substrate etching solution.

When the amount of the silicon additive in the silicon substrate etching solution is less than 100 ppm, the effect of increasing the selectivity of the silicon nitride layer to the silicon oxide layer may be insignificant. On the other hand, if the silicon additive in the silicon substrate etching solution exceeds 10,000 ppm, the etching rate of the silicon nitride film may decrease depending on the increased silicon concentration in the silicon substrate etching solution, and the silicon additive itself may act as a source of silicon-based particles. can work

In addition, the silicon substrate etching solution according to an embodiment of the present invention may include imidazolium phosphate represented by Chemical Formula 3 below.

[Formula 3]

Here, R ₁₁ to R ₁₄ are each independently 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 al kenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl and aralkyl.

In the present application, it has been described that the positively charged moiety of the salt that inhibits the growth of silicon-based particles through electrostatic interaction with the silicone additive is imidazolium, but other than imidazolium, the portion represented by the polar functional group of the silicone additive It will be understood that any moiety having a positive charge capable of electrostatic interaction with a negative charge may be used. Such positively charged moieties include thiophene, oxazole, thiazole, and the like.

In the present application, it has been described that the salt that inhibits the growth of silicon-based particles through electrostatic interaction with the silicon additive is a phosphate whose negatively charged moiety is phosphoric acid, but phosphoric acid is a negatively charged moiety of the salt. In addition, it will be understood that nitric acid and sulfuric acid are used, so that salts in the form of nitrate or sulfate may also be used.

The above-described imidazolium phosphate is preferably present in an amount of 100 to 20,000 ppm in the silicon substrate etching solution.

When imidazolium phosphate is present in an amount of less than 100 ppm in the silicon substrate etching solution, it is likely that it is difficult to induce sufficient electrostatic interaction with the silicon additive. Accordingly, even if imidazolium phosphate is present in the silicon substrate etching solution, growth of silicon-based particles cannot be effectively prevented.

Imidazolium phosphate can decompose into nitrogen oxides and ammonia at high temperatures, and these decomposition products can cause bubbling as they are released into the gaseous phase. If the imidazolium phosphate in the silicon substrate etching solution is present in excess of 20,000 ppm, the possibility of causing safety problems may increase due to a bubbling phenomenon under etching conditions (160 ° C. or higher).

As the imidazolium phosphate in the silicon substrate etching solution is present within the above-described content range, the pH of the silicon substrate etching solution at 25 ° C is 3 to 6.5, and the pH of the silicon substrate etching solution is maintained at 1 to 6.5 at 165 ° C. Generation of silicon-based particles in the substrate etching solution may be suppressed.

Weakly basic imidazolium phosphate increases the pH as it is added to the silicon substrate etching solution, and accordingly, the pH of the silicon substrate etching solution is relatively close to neutral (pH ≒ 7) under room temperature (≒ 25 ℃) conditions, resulting in silicon-based particles It is possible to inhibit the growth of

On the other hand, as a part of the imidazolium phosphate is decomposed under high temperature (≒ 165° C.) etching conditions, the pH of the silicon substrate etching solution may return to a state suitable for the etching conditions. At this time, imidazolium phosphate can be decomposed into a gaseous nitrogen mixture (nitrogen oxide and ammonia) and phosphoric acid.

The silicon substrate etching solution according to an embodiment of the present invention may further include a fluorine-containing compound in order to compensate for the etching rate of the silicon nitride film, which is reduced due to the use of the silicon additive, and to improve the efficiency of the overall etching process. .

A fluorine-containing compound herein refers to any type of compound capable of dissociating fluorine ions.

In one embodiment, the fluorine-containing compound is at least one selected from hydrogen fluoride, ammonium fluoride, ammonium bifluoride and ammonium bifluoride.

Also, in another embodiment, the fluorine-containing compound may be a compound in which an organic cation and a fluorine anion are ionically bonded.

For example, the fluorine-containing compound may be a compound in which an alkylammonium and a fluorine-based anion are ionically bonded. Here, the alkylammonium is ammonium having at least one alkyl group and may have up to four alkyl groups. The definition of the alkyl group has been described above.

In another example, the fluorine-containing compound is an alkylpyrroleium, an alkylimidazolium, an alkylpyrazolium, an alkyloxazolium, an alkylthiazolium, an alkylpyridinium, an alkylpyrimidinium, an alkylpyridazinium, an alkylpyrazolium. An organic cation selected from zinium, alkylpyrrolidinium, alkylphosphonium, alkylmorphorinium and alkylpiperidinium, and fluorophosphate, fluoroalkyl-fluorophosphate, fluoroborate and fluoroalkyl-fluoro It may be an ionic liquid in which a fluorine-based anion selected from Roborate is ionically bonded.

Compared to hydrogen fluoride or ammonium fluoride, which are generally used as fluorine-containing compounds in silicon substrate etching solutions, fluorine-containing compounds provided in the form of ionic liquids have a higher boiling point and decomposition temperature, so they are decomposed during the etching process performed at high temperatures. There is an advantage in that there is little risk of changing the composition of the etching solution according to.

Hereinafter, specific embodiments of the present invention are presented. However, the embodiments described below are only intended to specifically illustrate or explain the present invention, and the present invention should not be limited thereto.

Composition of the silicon substrate etching solution

Example 1

A silicon substrate etching solution was prepared by mixing 85% by weight of phosphoric acid, 500 ppm of triethoxyhydroxysilane, 5,000 ppm of imidazolium phosphate represented by the following chemical formula, and the remaining amount of water.

Example 2

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that imidazolium phosphate represented by the following chemical formula was used.

Example 3

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that 500 ppm of ammonium fluoride was further included.

Comparative Example 1

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that imidazolium phosphate was not used.

Comparative Example 2

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that ammonium phosphate was used instead of imidazolium phosphate.

Experimental example

After heating the silicon substrate etching solution having the composition according to each Example and Comparative Example to 165 ° C., cooling it to room temperature (25 ° C.), and then etching the silicon substrate according to the pH and elapsed time before / after boiling of the silicon substrate etching solution The degree of generation of particles in the solution was measured.

The degree of generation of particles in the silicon substrate etching solution was analyzed by analyzing the etching solution with a particle size analyzer to measure the average diameter of silicon-based particles present in the etching solution.

The pH measurement results of the silicon substrate etching solution before and after the temperature increase are shown in Table 1 below, and the degree of particle generation in the silicon substrate etching solution is shown in Tables 2 and 3 below.

division Before temperature rise (165℃) After temperature rise (165℃) Example 1 5.02 2.31 Example 2 5.05 2.29 Example 3 5.11 2.31 Comparative Example 1 2.28 2.28 Comparative Example 2 5.07 2.28

Referring to the results of Table 1, the silicon substrate etching solution according to Examples 1 to 3 and Comparative Example 2 to which a nitrogen-containing salt of a weak base was added had a pH of about 5.0 at room temperature (25 ° C) before being heated to 165 ° C. It can be confirmed that the pH is indicated. That is, by maintaining the pH of the etching solution close to neutral during storage of the silicon substrate etching solution at room temperature, there is a high possibility of inhibiting the growth of silicon-based particles from the silicon additive. On the other hand, in the case of Comparative Example 1 in which the weak base additive was not added, there was no change in pH before/after heating, and thus, there is a high possibility that silicon-based particles may grow from the etching solution even during storage at room temperature.

Table 2 below shows the results of measuring the average diameter of particles present in the silicon substrate etching solution according to the time left at room temperature before the temperature was raised to 165 ° C.

division Elapsed time (hr) One 5 16 72 Example 1 < 0.1 µm < 0.1 µm < 0.1 µm < 0.1 µm Example 2 < 0.1 µm < 0.1 µm < 0.1 µm < 0.1 µm Example 3 < 0.1 µm < 0.1 µm < 0.1 µm < 0.1 µm Comparative Example 1 3.6 μm 4.1 μm 4.8 μm 5.5 μm Comparative Example 2 < 0.1 µm < 0.1 µm < 0.1 µm < 0.1 µm

Referring to the results of Table 2, the silicon substrate etching solutions according to Examples 1 to 3 and Comparative Example 2 to which a nitrogen-containing salt of a weak base was added had a pH of about 5.0 at room temperature (25° C.) before being heated to 165° C. According to the pH, it can be confirmed that the growth of silicon-based particles is inhibited. On the other hand, in the case of Comparative Example 1 in which the weak base additive was not added, as the pH was acidic even before the temperature was raised, it could be confirmed that silicon-based particles grew from the etching solution even during storage at room temperature.

Table 3 below shows the results of measuring the average diameter of particles present in the silicon substrate etching solution according to the elapsed time after the temperature was raised to 165 °C.

division Elapsed time (hr) One 5 16 72 Example 1 < 0.1 µm < 0.1 µm < 0.1 µm < 0.1 µm Example 2 < 0.1 µm < 0.1 µm < 0.1 µm < 0.1 µm Example 3 0.15 μm 0.17 μm 0.18 μm 0.19 μm Comparative Example 1 5.5 μm 7 μm 9.2 μm > 10 µm Comparative Example 2 2.4 μm 3.1 μm 4.5 μm 4.8 μm

Referring to the results of Table 3, it can be confirmed that the growth of silicon-based particles is suppressed even after the temperature is raised to 165 ° C. can On the other hand, in the case of Comparative Example 1 in which the weak base additive was not added, after the temperature was raised, it was confirmed that the silicon-based particles grew more than before the temperature was raised.

In addition, in the case of Comparative Example 2 in which ammonium phosphate was added, as ammonium was all vaporized in the form of ammonia under high temperature conditions, the stabilizing effect of the silicon additive by ammonium disappeared, and thus it could be confirmed that silicon-based particles grew.

In the above, one embodiment of the present invention has been described, but those skilled in the art can add, change, delete, or add components within the scope not departing from the spirit of the present invention described in the claims. The present invention can be variously modified and changed by the like, and this will also be said to be included within the scope of the present invention.

Claims (8)

inorganic acid aqueous solution;
A silicone additive represented by Formula 1 or Formula 2 below; and
imidazolium phosphate represented by Formula 3 below;
including,
Silicon Substrate Etch Solution:
[Formula 1]

[Formula 2]

[Formula 3]

Here, R ₁ to R ₄ are each independently 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 Al kenyl, C ₂ -C ₁₀ alkynyl, C ₁ -C ₁₀ haloalkyl, C ₁ -C ₁₀ aminoalkyl, aryl, heteroaryl, aralkyl and hydroxy, amino, halogen, sulfone, phosphonic, phosphoric, cy selected from ol, alkoxy, amide, ester, acid anhydride, acyl halide, cyano, carboxyl and azole, wherein at least one of R ₁ to R ₄ is a polar functional group;
R ₅ to R ₁₀ are each independently 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 and hydroxy, amino, halogen, sulfone, phosphonic, phosphoric, thiol, It is selected from alkoxy, amide, ester, acid anhydride, acyl halide, cyano, carboxyl and azole, wherein at least one of R ₅ to R ₁₀ is a polar functional group, n is an integer from 1 to 5,
R ₁₁ to R ₁₄ are each independently 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 and aralkyl.
According to claim 1,
The inorganic acid aqueous solution is an aqueous solution containing at least one inorganic acid selected from sulfuric acid, nitric acid, phosphoric acid, silicic acid, hydrofluoric acid, boric acid, hydrochloric acid, perchloric acid, anhydrous phosphoric acid, pyrophosphoric acid and polyphosphoric acid,
Silicon substrate etching solution.
According to claim 1,
The silicon additive in the silicon substrate etching solution is contained in 100 to 10,000 ppm,
Silicon substrate etching solution.
According to claim 1,
The imidazolium phosphate in the silicon substrate etching solution is contained in 100 to 20,000 ppm,
Silicon substrate etching solution.
According to claim 1,
The pH of the silicon substrate etching solution at 25 ° C is 3 to 6.5,
Silicon substrate etching solution.
According to claim 1,
The pH of the silicon substrate etching solution at 165 ° C is 1 to 6.5,
Silicon substrate etching solution.
According to claim 1,
further comprising at least one fluorine-containing compound selected from hydrogen fluoride, ammonium fluoride, ammonium bifluoride and ammonium hydrogen fluoride;
Silicon substrate etching solution.
According to claim 1,
Further comprising a fluorine-containing compound having an ionically bonded form of an organic cation and a fluorine anion,
Silicon substrate etching solution.