KR102507051B1 - Etching solution for silicon nitride layer - Google Patents

Abstract

The present invention includes an aqueous solution of an inorganic acid, a first silane compound having three or more hydrophilic functional groups independently bonded to a silicon atom, a second silane compound having one or two hydrophilic functional groups independently bonded to a silicon atom, and a fluorine-containing compound. As a silicon nitride film etching solution, heterogeneous silane compounds with different numbers of hydrophilic functional groups bound to silicon atoms are used to prevent an increase in the etching rate of the silicon oxide film due to excess fluorine present in the etching solution, and at the same time to prevent silicon-based particles from being etched. production can be inhibited.

Description

Silicon nitride film etching solution {ETCHING SOLUTION FOR SILICON NITRIDE LAYER}

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

Currently, there are various methods of etching a silicon nitride film and a silicon oxide film, and 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, and etching of a silicon nitride film by phosphoric acid proceeds through the following chemical reaction.

4H ₃ PO ₄ + 3Si ₃ N ₄ + 27H ₂ O 4 (NH ₄ ) ₃ PO ₄ + 9H ₂ SiO ₃

If only pure phosphoric acid is used for etching 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. There is a need.

On the other hand, there has been an attempt to use a compound containing fluorine as an additive to further increase the etching rate of a silicon nitride film, but fluorine has a disadvantage in that it also increases the etching rate of a silicon oxide film.

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.

However, since the silane compound mainly used as a silicon additive basically has low solubility in an etching solution containing phosphoric acid, a hydrophilic functional group (eg, a hydroxyl group) is added to the silicon atom to increase the solubility of the silane compound in the etching solution. ) is used in the form of a bonded silane compound.

When a silane compound in which a hydrophilic functional group is bonded to a silicon atom is used as a silicon additive, appropriate solubility of the silane compound in an etching solution may be secured, but several problems may occur.

First, when the concentration of the silane compound in the etching solution is increased in order to increase the selectivity of the silicon nitride film to the silicon oxide film, the etching rate of the silicon nitride film is rather reduced depending on the increased silicon concentration in the etching solution. .

That is, as the silicon additive is used, the concentration of silicon in the etching solution is increased to adjust the etching rate according to the principle of Le Chatelier chemical equilibrium. In addition, the etching rate for the silicon nitride film is lowered, resulting in a decrease in productivity.

Second, the increased concentration of silicon in the etching solution due to the use of a silane compound as a silicon additive can act as a source (nucleus or seed) of silicon-based particles, and silicon-based particles generated during etching or post-etching cleaning of the etched and cleaned substrate It acts as the biggest cause of defects in

For example, a hydrophilic functional group bonded to a silicon atom may be substituted with a hydroxyl group to form a silicon-hydroxyl group (-Si-OH) by meeting H ₂ O during etching or washing, and the silicon-hydroxyl group may be polymerized. As a result, silicon atoms and oxygen atoms are alternately bonded to form a siloxane (-Si-O-Si-) group forming a random chain structure.

As a result, the silane compound containing the siloxane group grows and precipitates as silicon-based particles in which the siloxane group is repeatedly polymerized, and the silicon-based particles remain on the silicon substrate to cause defects in devices implemented on the substrate or equipment used in etching or cleaning processes. (e.g. filters) and may cause equipment failure.

Therefore, there is an urgent need to develop a silicon nitride film etching solution capable of suppressing the generation of silicon-based particles during etching or cleaning after etching.

An object of the present invention is to provide a silicon nitride film etching solution capable of increasing the selectivity of a silicon nitride film to a silicon oxide film by using a silane compound-based silicon additive.

In addition, an object of the present invention is to provide a silicon nitride film etching solution capable of compensating for an etching rate that is lowered due to the use of a silicon additive as a result of the use of a fluorine-containing compound.

In addition, the present invention prevents the increase in the etching rate of the silicon oxide film due to excessive fluorine present in the etching solution by using heterogeneous silane compounds having different numbers of hydrophilic functional groups bonded to silicon atoms, and at the same time generates silicon-based particles. It is an object of the present invention to provide a silicon nitride film etching solution capable of suppressing.

In order to solve the above technical problem, according to one aspect of the present invention, a first silane compound containing an inorganic acid solution, 1 to 6 silicon atoms, and including at least one silicon atom to which three or more hydrophilic functional groups are bonded. , A silicon nitride film etching solution including a second silane compound containing 1 to 6 silicon atoms and having a maximum of two hydrophilic functional groups bonded to one silicon atom and a fluorine-containing compound may be provided.

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, perchloric acid, anhydrous phosphoric acid, pyrophosphoric acid, and polyphosphoric acid.

The hydrophilic functional group may be a hydroxyl group or a functional group substitutable with a hydroxyl group under the pH condition of an aqueous inorganic acid solution, and the functional group substitutable with a hydroxyl group under the pH condition of an aqueous inorganic acid solution may be an amino group, a halogen group, a sulfone group, a phosphonic group, a phosphonic group, and a phosphonic group. It may be selected from a foric group, a thiol group, an alkoxy group, an amide group, an ester group, an acid anhydride group, an acyl halide group, a cyano group, a carboxyl group and an azole group.

In one embodiment, the first silane compound may be represented by Formula 1 or Formula 2 below.

[Formula 1]

(Where, 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 including 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.)

[Formula 2]

(Where, 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 including 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; n is an integer from 1 to 5.)

In one embodiment, the second silane compound may be represented by Formula 3 or Formula 4 below.

[Formula 3]

(Where, R ₁₁ to R ₁₄ are each independently a hydrophilic functional group, or hydrogen, C ₁ -C ₁₀ alkyl, C ₆ -C ₁₂ cycloalkyl, C ₂ -C ₁₀ heteroalkyl including 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, silyloxy and siloxane.)

[Formula 4]

(Where, R ₁₅ to R ₂₀ are each independently a hydrophilic functional group, or hydrogen, C ₁ -C ₁₀ alkyl, C ₆ -C ₁₂ cycloalkyl, C ₂ -C ₁₀ heteroalkyl including 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, silyloxy and siloxane; n is an integer from 1 to 5.)

In one embodiment, the fluorine-containing compound is at least one selected from hydrogen fluoride, ammonium fluoride and ammonium hydrogen fluoride. In another embodiment, the fluorine-containing compound may be a compound in which an organic cation and a fluorine anion are ionically bonded.

The silicon nitride film etching solution according to the present invention can increase the selectivity of the silicon oxide film to the silicon nitride film by using a silane compound-based silicon additive, and further includes a fluorine-containing compound to prevent etching that is deteriorated according to the use of the silicon additive. It has the advantage that it is possible to compensate for the speed.

In addition, since the silicon nitride film etching solution according to the present invention uses heterogeneous silane compounds having different numbers of hydrophilic functional groups bound to silicon atoms, it is possible to prevent an increase in the etching rate of the silicon oxide film due to excess fluorine present in the etching solution. can

In addition, since the silicon nitride film etching solution according to the present invention can effectively suppress the generation of silicon-based particles, it prevents defects of the silicon substrate or failure of the etching and cleaning apparatus caused by the generation of silicon-based particles during etching or cleaning after etching. can do.

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 nitride film etching solution according to the present invention will be described in detail.

According to one aspect of the present invention, an aqueous solution of an inorganic acid, a first silane compound containing 1 to 6 silicon atoms, and including at least one silicon atom to which three or more hydrophilic functional groups are bonded, 1 to 6 silicon atoms And, a silicon nitride film etching solution including a second silane compound having a maximum of two hydrophilic functional groups bonded to one silicon atom and a fluorine-containing compound may be provided.

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 nitride film 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 nitride film 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 nitride film etching solution, the etching rate of the silicon nitride film is excessively increased 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 nitride film etching solution according to an embodiment of the present invention includes a first silane compound represented by Formula 1 or Formula 2 below to increase the selectivity of the silicon nitride film to the silicon oxide film.

As represented by Formula 1 below, the first silane compound herein may be defined as a compound in which functional groups of R ₁ to R ₄ are bonded to one silicon atom. Here, at least three of R ₁ to R ₄ are hydrophilic functional groups.

[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.

In addition, as represented by Formula 2 below, the first silane compound 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.

That is, the first silane compound includes 1 to 6 silicon atoms, but includes at least one silicon atom to which three or more hydrophilic functional groups are bonded, thereby ensuring sufficient solubility in the silicon nitride film etching solution containing an inorganic acid aqueous solution. it is possible

In addition, since the first silane compound includes at least one silicon atom to which three or more hydrophilic functional groups are bonded, it is possible to form a relatively strong hydrophilic interaction with the silicon substrate, particularly the silicon oxide layer.

The first silane compound attached to the surface of the silicon oxide layer through a strong hydrophilic interaction may serve to prevent the silicon oxide layer from being etched by an inorganic acid or a fluorine-containing compound.

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 the present application, the pH condition of the inorganic acid aqueous solution means 4 or less. When the pH condition of the inorganic acid aqueous solution exceeds 4, the stability of the first silane compound present in the silicon nitride film etching solution is deteriorated due to the relatively high pH, which may act as a source of silicon-based particles.

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 ).

A hydrocarbon ring (cycloalkyl) or a hydrocarbon ring containing a hetero atom (heterocycloalkyl) herein may be understood as a cyclic structure of alkyl or heteroalkyl, respectively, unless otherwise defined.

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

Non-limiting examples of hydrocarbon rings 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, a hydrocarbon ring or a hydrocarbon ring including a hetero atom may have a form in which a hydrocarbon ring, a hydrocarbon ring including a hetero atom, an aryl, or a hetero aryl are conjugated or covalently bonded thereto.

In the present application, silyloxy is a functional group in which silyl is substituted for oxygen, and is a generic term for -O-Si(R) ₃ .

The above-described first silane compound is preferably present in an amount of 100 to 10,000 ppm in the silicon nitride film etching solution.

When the amount of the first silane compound in the silicon nitride film etching solution is less than 100 ppm, the effect of increasing the selectivity of the silicon nitride film to the silicon oxide film may be insignificant. On the other hand, when the amount of the first silane compound in the silicon nitride film etching solution exceeds 10,000 ppm, the etching rate of the silicon nitride film may be lowered according to the increased silicon concentration in the silicon nitride film etching solution, and the first silane compound itself may be a silicon based compound. It can act as a source of particles.

The silicon nitride film etching solution according to an embodiment of the present invention includes a fluorine-containing compound to compensate for the etching rate of the silicon nitride film, which is reduced by including the first silane compound as a silicon additive, and to improve the efficiency of the overall etching process. can include more.

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 nitride film 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.

However, when there is an excessive amount of fluorine or fluorine ions remaining in the etching solution as an excessive amount of fluorine-containing compounds are included in the etching solution for the silicon nitride film, the etching rate for the silicon nitride film as well as the silicon oxide film may increase. .

Accordingly, according to the present invention, by additionally including a second silane compound represented by Chemical Formula 3 or Chemical Formula 4 in the silicon nitride film etching solution, the problem of increasing the etching rate of the silicon oxide film caused by the fluorine-containing compound is suppressed. possible.

As represented by Formula 3 below, the second silane compound herein may be defined as a compound in which functional groups of R ₁₁ to R ₁₄ are bonded to one silicon atom. Here, one or two hydrophilic functional groups are selected from among R ₁₁ to R ₁₄ .

[Formula 3]

Here, R ₁₁ to R ₁₄ 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.

In addition, as represented by Formula 4 below, the second silane compound herein may be defined as a silane compound in which at least two silicon atoms are continuously bonded.

[Formula 4]

Here, R ₁₅ to R ₂₀ 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.

That is, the second silane compound includes 1 to 6 silicon atoms, but includes a hydrophilic functional group bonded to the silicon atoms, thereby having a form capable of securing an appropriate level of solubility into a silicon nitride film etching solution containing an inorganic acid solution. .

Accordingly, the second silane compound present in an appropriately dissolved state in the silicon nitride film etching solution properly reacts with the fluorine-containing compound present in excess compared to the first silane compound, thereby preventing an increase in the etching rate of the silicon oxide film. .

In addition, since the second silane compound has a smaller number of hydrophilic functional groups than the first silane compound, the possibility of acting as a nucleus of silicon-based particles can be minimized.

In particular, as the second silane compound has a maximum of two hydrophilic functional groups to ensure solubility in a silicon nitride film etching solution, it may have a maximum of two silicon-hydroxyl groups (-Si-OH) under the pH condition of an inorganic acid aqueous solution.

Here, the meaning that the second silane compound has a maximum of two hydrophilic functional groups means that the maximum number of hydrophilic functional groups bonded to one silicon atom is two. In addition, it is preferable that the second silane compound has at least one hydrophilic functional group in order to secure solubility in the silicon nitride film etching solution.

Accordingly, when one silicon atom constituting the second silane compound is used, one or two hydrophilic functional groups among four functional groups bonded to the silicon atom are preferred. In addition, when the number of silicon atoms constituting the second silane compound is two or more, it is preferable to include at least one silicon atom bonded to at least one and at most two hydrophilic functional groups.

At this time, when the hydrophilic functional group of the second silane compound is substituted with a silicon-hydroxy group (-Si-OH) under the pH condition of the inorganic acid aqueous solution, the second silane compound has a silicon-hydroxy group (-Si-OH) Through polymerization with the first silane compound or the second silane compound to grow into a silicone dimer, silicone oligomer or silicone oil having a regular one-dimensional or two-dimensional arrangement, the generation of silicon-based particles by random growth has not been previously demonstrated it is possible to prevent

The above-described second silane compound is preferably present in an amount of 100 to 30,000 ppm in the silicon nitride film etching solution.

When the second silane compound in the silicon nitride film etching solution is present in an amount of less than 100 ppm, it is difficult to suppress etching of the silicon oxide film by the fluorine-containing compound present in excess, as well as the generation of silicon-based particles caused by the first silane compound. It can be difficult to contain.

As described above, the silicon nitride film etching solution according to the present invention has the advantage of maintaining a high selectivity of the silicon nitride film to the silicon oxide film and controlling the generation of silicon-based particles during etching or cleaning after etching.

Accordingly, when the silicon nitride film is etched at 165° C. for 1 minute with the silicon nitride film etching solution according to the present invention, the average diameter of the generated silicon-based particles may be 0.1 μm or less.

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.

Example

Table 1 below shows the composition of the silicon nitride film etching solution according to the embodiment.

division First silane compound (ppm) Second silane compound (ppm) Fluorine-Containing Compounds (ppm) Example 1 500 300 300 Example 2 1,000 800 500 Example 3 2,000 2,000 2,000 Example 4 4,000 1,500 2,500 Example 5 5,000 4,000 5,500 Example 6 8,000 5,000 3,000 Example 7 10,000 8,000 2,000 Example 8 10,000 22,000 1,000

The silicon nitride film etching solutions according to Examples 1 to 8 include 85% by weight of phosphoric acid and the balance of water, and the first silane compound, the second silane compound, and the fluorine-containing compound are included in ppm units shown in Table 1. do.

Example 1 used tetrahydroxysilane as the first silane compound, trimethylhydroxysilane as the second silane compound, and hydrogen fluoride as the fluorine-containing compound.

Example 2 used tetrahydroxysilane as the first silane compound, trimethylhydroxysilane as the second silane compound, and ammonium bifluoride as the fluorine-containing compound.

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

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

Example 5 used hexahydroxydisiloxane as the first silane compound, 1,3-disiloxanediol as the second silane compound, and ammonium fluoride as the fluorine-containing compound.

Example 6 used trimethoxyhydroxysilane as the first silane compound, trimethylhydroxysilane as the second silane compound, and hydrogen fluoride as the fluorine-containing compound.

Example 7 used butyltrihydroxysilane as the first silane compound, trimethylhydroxysilane as the second silane compound, and hydrogen fluoride as the fluorine-containing compound.

Example 8 used tetrahydroxysilane as the first silane compound, chlorotrimethylsilane as the second silane compound, and hydrogen fluoride as the fluorine-containing compound.

comparative example

Table 2 below shows the composition of the silicon nitride film etching solution according to the comparative example.

division First silane compound (ppm) Fluorine-Containing Compounds (ppm) Comparative Example 1 500 400 Comparative Example 2 500 500 Comparative Example 3 500 700 Comparative Example 4 500 500

Silicon nitride film etching solutions according to Comparative Examples 1 to 4 include phosphoric acid of 85% by weight and the remaining amount of water, and the first silane compound and the fluorine-containing compound are included in ppm units shown in Table 1.

Comparative Example 1 used tetrahydroxysilane as the first silane compound and hydrogen fluoride as the fluorine-containing compound.

Comparative Example 2 used tetrahydroxysilane as the first silane compound and ammonium bifluoride as the fluorine-containing compound.

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

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

Experimental example

After boiling for 0.5h, 1h, and 2h at each temperature (145 ° C, 157 ° C, 165 ° C) using the silicon nitride film etching solution having the composition according to each Example and Comparative Example, the silicon nitride film and the silicon oxide film are etched for 1 minute did The silicon oxide film is a thermally grown oxide film and exhibits an etching rate of 2 Å/min in a 165° C. pure phosphoric acid solution.

The silicon nitride film and the silicon oxide film were planarized before being put into the etching solution, and the planarization was performed by immersing in diluted hydrofluoric acid for 30 seconds after hydrogen fluoride diluted with 50% by mass hydrofluoric acid at a ratio of 200:1.

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

For the etching rate, the average etching amount per minute was calculated with an ellipsometer after etching at 165° C. for 5 minutes.

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

Example 1 0.5h 1h 2h 165℃ <0.01 μm <0.01 μm <0.01 μm Etch amount per minute at 165℃ (Å) 1.4 1.3 1.4 157℃ <0.01 μm <0.01 μm <0.01 μm 145℃ <0.01 μm <0.01 μm <0.01 μm

Example 2 0.5h 1h 2h 165℃ <0.01 μm <0.01 μm <0.01 μm Etch amount per minute at 165℃ (Å) 1.7 1.7 1.8 157℃ <0.01 μm <0.01 μm <0.01 μm 145℃ <0.01 μm <0.01 μm <0.01 μm

Example 3 0.5h 1h 2h 165℃ <0.01 μm <0.01 μm <0.01 μm Etch amount per minute at 165℃ (Å) 2.0 2.1 1.9 157℃ <0.01 μm <0.01 μm <0.01 μm 145℃ <0.01 μm <0.01 μm <0.01 μm

Example 4 0.5h 1h 2h 165℃ <0.01 μm <0.01 μm <0.01 μm Etch amount per minute at 165℃ (Å) 1.8 1.8 1.7 157℃ <0.01 μm <0.01 μm <0.01 μm 145℃ <0.01 μm <0.01 μm <0.01 μm

Example 5 0.5h 1h 2h 165℃ <0.01 μm <0.01 μm <0.01 μm Etch amount per minute at 165℃ (Å) 1.9 1.8 1.8 157℃ <0.01 μm <0.01 μm <0.01 μm 145℃ <0.01 μm <0.01 μm <0.01 μm

Example 6 0.5h 1h 2h 165℃ <0.01 μm <0.01 μm <0.01 μm Etch amount per minute at 165℃ (Å) 1.7 1.7 1.8 157℃ <0.01 μm <0.01 μm <0.01 μm 145℃ <0.01 μm <0.01 μm <0.01 μm

Example 7 0.5h 1h 2h 165℃ <0.01 μm <0.01 μm <0.01 μm Etch amount per minute at 165℃ (Å) 1.9 2.0 2.0 157℃ <0.01 μm <0.01 μm <0.01 μm 145℃ <0.01 μm <0.01 μm <0.01 μm

Example 8 0.5h 1h 2h 165℃ <0.01 μm <0.01 μm <0.01 μm Etch amount per minute at 165℃ (Å) 1.8 1.8 1.8 157℃ <0.01 μm <0.01 μm <0.01 μm 145℃ <0.01 μm <0.01 μm <0.01 μm

As a result of particle size analysis of the silicon nitride film etching solution having the composition according to Examples 1 to 8, it was confirmed that no silicon-based particles were present in the etching solution or that the diameter was 0.01 μm or less, which was extremely fine.

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

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

On the other hand, as a result of particle size analysis of the silicon nitride film etching solutions having the compositions according to Comparative Examples 1 to 4, it was confirmed that silicon-based particles having a diameter of 20 μm or more were present in the etching solution as shown in Tables 11 to 14 below. .

In addition, it can be confirmed that the etch rate per minute of the silicon oxide film is increased by the fluorine-containing compound.

Comparative Example 1 0.5h 1h 2h 165℃ 32.7 μm 33.8 μm 32.9 μm Etch amount per minute at 165℃ (Å) 4.7 4.5 4.2 157℃ 26.8 μm 29.4 μm 29.7 μm 145℃ 23.5 μm 24.3 μm 24.5 μm

Comparative Example 2 0.5h 1h 2h 165℃ 53.7 μm 55.4 μm 54.8 μm Etch amount per minute at 165℃ (Å) 5.2 5.1 4.8 157℃ 48.3 μm 47.7 μm 49.3 μm 145℃ 41.3 μm 42.2 μm 44.4 μm

Comparative Example 3 0.5h 1h 2h 165℃ 44.8 μm 45.7 μm 48.1 μm Etch amount per minute at 165℃ (Å) 7.8 7.4 7.3 157℃ 39.8 μm 41.1 μm 41.5 μm 145℃ 38.1 μm 38.8 μm 40.6 μm

Comparative Example 4 0.5h 1h 2h 165℃ 35.3 μm 36.6 μm 37.0 µm Etch amount per minute at 165℃ (Å) 6.3 6.2 6.1 157℃ 33.1 μm 32.8 μm 34.3 μm 145℃ 29.1 μm 30.7 μm 31.5 μm

Although one embodiment of the present invention has been described above, 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 (14)

inorganic acid aqueous solution;
a first silane compound including 1 to 6 silicon atoms and including at least one silicon atom bonded to three or more hydrophilic functional groups;
a second silane compound containing 1 to 6 silicon atoms and having a maximum of two hydrophilic functional groups bonded to one silicon atom; and
Including; fluorine-containing compound,
The hydrophilic functional group is 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,
Under the pH condition of the inorganic acid aqueous solution, the functional group capable of being substituted with a hydroxyl group is an amino group, a halogen group, a sulfone group, a phosphonic group, a phosphoric group, a thiol group, an alkoxy group, an amide group, an ester group, an acid anhydride group, an acyl halide group, selected from cyano groups, carboxyl groups and azole groups;
Silicon nitride film etching solution.
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 nitride film etching solution.
delete delete According to claim 1,
The first silane compound is a silicon nitride film etching solution represented by Formula 1 or Formula 2 below:
[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 a functional group selected from siloxane, wherein the hydrophilic functional group is Selected from a hydroxy group, an amino group, a halogen group, a sulfone group, a phosphonic group, a phosphoric group, a thiol group, an alkoxy group, an amide group, an ester group, an acid anhydride group, an acyl halide group, a cyano group, a carboxyl group, and an azole group It is a functional group that becomes.)

[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, wherein the hydrophilic functional group is Selected from a hydroxyl group, an amino group, a halogen group, a sulfone group, a phosphonic group, a phosphoric group, a thiol group, an alkoxy group, an amide group, an ester group, an acid anhydride group, an acyl halide group, a cyano group, a carboxyl group, and an azole group It is a functional group that becomes
n is an integer from 1 to 5.)
delete According to claim 1,
The first silane compound in the silicon nitride film etching solution is contained in 100 to 10,000 ppm,
Silicon nitride film etching solution.
According to claim 1,
The second silane compound is a silicon nitride film etching solution represented by Formula 3 and Formula 4 below:
[Formula 3]

(here,
R ₁₁ to R ₁₄ 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, wherein the hydrophilic functional group is Selected from a hydroxyl group, an amino group, a halogen group, a sulfone group, a phosphonic group, a phosphoric group, a thiol group, an alkoxy group, an amide group, an ester group, an acid anhydride group, an acyl halide group, a cyano group, a carboxyl group, and an azole group It is a functional group that becomes.)

[Formula 4]

(here,
R ₁₅ to R ₂₀ 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, wherein the hydrophilic functional group is Selected from a hydroxyl group, an amino group, a halogen group, a sulfone group, a phosphonic group, a phosphoric group, a thiol group, an alkoxy group, an amide group, an ester group, an acid anhydride group, an acyl halide group, a cyano group, a carboxyl group, and an azole group is a functional group, and n is an integer from 1 to 5.)
delete According to claim 1,
The second silane compound in the silicon nitride film etching solution is included in 100 to 30,000 ppm,
Silicon nitride film etching solution.
According to claim 1,
The fluorine-containing compound is at least one selected from hydrogen fluoride, ammonium fluoride, ammonium bifluoride and ammonium hydrogen fluoride,
Silicon nitride film etching solution.
According to claim 1,
The fluorine-containing compound is a compound having an ionic bond of an organic cation and a fluorine anion,
Silicon nitride film etching solution.
According to claim 12,
The organic cations are alkylammonium, alkylpyrroleium, alkylimidazolium, alkylpyrazolium, alkyloxazolium, alkylthiazolium, alkylpyridinium, alkylpyrimidinium, alkylpyridazinium, alkylpyrazinium, alkyl selected from pyrrolidinium, alkylphosphonium, alkylmorpholinium and alkylpiperidinium;
Silicon nitride film etching solution.
According to claim 12,
The fluorine-based anion is selected from fluoride, fluorophosphate, fluoroalkyl-fluorophosphate, fluoroborate and fluoroalkyl-fluoroborate,
Silicon nitride film etching solution.