KR20200072028A - Etching solution for silicon substrate and method for preparing semiconductor device using the same - Google Patents

Abstract

The present invention relates to a silicon substrate etching solution and, more specifically, to a silicon substrate etching solution capable of improving etching selectivity of a silicon nitride film compared to a silicon oxide film when etching the silicon nitride film by adjusting the concentration of a silane compound (eg, silicic acid) in the silicon substrate etching solution.

Description

Silicon substrate etching solution and manufacturing method of semiconductor device using the same{ETCHING SOLUTION FOR SILICON SUBSTRATE AND METHOD FOR PREPARING SEMICONDUCTOR DEVICE USING THE SAME}

The present invention relates to a method for manufacturing a semiconductor device using the silicon substrate etching solution, and more specifically, by controlling the concentration of a silane compound (eg, silicic acid) in the silicon substrate etching solution, compared to a silicon oxide film when etching the silicon nitride film A silicon substrate etching solution capable of improving an etch selectivity to a silicon nitride film and a method of manufacturing a semiconductor device including an etching process performed using the same.

At present, there are various methods of etching the silicon nitride film and the silicon oxide film, and the dry etching method and the wet etching method are mainly used.

The dry etching method is an etching method using a gas, and has an advantage in that isotropy is superior to the wet etching method, but the wet etching method is widely used because it is much less expensive and more expensive than the wet etching method.

In general, a method of using phosphoric acid as an etching solution is well known as a wet etching method. At this time, if only pure phosphoric acid is used for etching the silicon nitride film, problems such as various defects and pattern abnormalities may occur due to the etching of the silicon nitride film as well as the silicon nitride film as the device becomes fine, so the etching rate of the silicon oxide film is etched. Needs to be lowered further.

The present invention is to increase the concentration of the silane compound (for example, silicic acid) in the silicon substrate etching solution to lower the etching rate for the silicon oxide film to improve the etching selectivity for the silicon nitride film compared to the silicon oxide film silicon substrate etching solution It aims to provide.

In addition, an object of the present invention is to provide a silicon substrate etching solution capable of preventing the silicon oxide film from being reduced to an etching rate with respect to the silicon nitride film or from forming silicon-based particles.

In addition, an object of the present invention is to provide a method of manufacturing a semiconductor device including an etching process performed using the above-described silicon substrate etching solution.

In order to solve the above technical problem, according to an aspect of the present invention, a silicon substrate etching solution including an aqueous phosphoric acid solution and a silicone additive represented by Formula 1 below is provided.

[Formula 1]

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 including 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 All, alkoxy, amide, ester, acid anhydride, acyl halide, cyano, carboxyl and azole, and at least one of R ₁ to R ₄ is heteroaryl.

The solubility of the silicone additive used in the silicon substrate etching solution according to one aspect of the present invention in an aqueous solution of 85% phosphoric acid at 25°C and 1 bar is preferably 100 ppm or more.

In addition, according to another aspect of the present invention, a method of manufacturing a semiconductor device including an etching process performed using the above-described silicon substrate etching solution is provided.

The silicon additive used in the present invention can lower the etching rate for the silicon oxide film by increasing the concentration of the silane compound (eg, silicic acid) in the silicon substrate etching solution under the etching conditions of the silicon substrate.

At this time, the silicone additive used herein can secure a sufficient solubility in the silicon substrate etching solution by including a hydrophilic heteroaryl group bonded to a silicon atom.

Advantages and features of the present invention, and a method of achieving them will be clarified with reference to embodiments described below. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only the present embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains. It is provided to completely inform the person having the scope of the invention, and the present invention is only defined by the scope of the claims.

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

According to an aspect of the present invention, a silicon substrate etching solution is provided that includes an aqueous phosphoric acid solution and a silicone additive represented by Formula 1 below.

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

Here, the silicon oxide film is a SOD (Spin On Dielectric) film, a HDP (High Density Plasma) film, a thermal oxide film, a BPSG (Borophosphate Silicate Glass) film, a PSG (Phospho Silicate Glass) film, depending on the purpose and type of material. , BSG (Boro Silicate Glass) membrane, PSZ (Polysilazane) membrane, FSG (Fluorinated Silicate Glass) membrane, LP-TEOS (Low Pressure Tetra Ethyl Ortho Silicate) membrane, PETEOS (Plasma Enhanced Tetra Ethyl Ortho Silicate) membrane, HTO (High Temperature Oxide (MTO) 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 aqueous phosphoric acid solution is a component that inhibits the change of various types of silane compounds present in the etching solution into silicon-based particles by etching the silicon nitride film and maintaining the pH of the etching solution.

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

When the content of the phosphoric acid aqueous solution is less than 60 parts by weight based on 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 process efficiency of etching the silicon nitride film may be deteriorated.

On the other hand, when the content of the phosphoric acid aqueous 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 is not only excessively increased, but also the silicon oxide film is rapidly etched, so that the silicon nitride film is compared to the silicon nitride film. The selectivity may be lowered, and defects in the silicon substrate due to etching of the silicon oxide film may be caused.

The silicon substrate etching solution according to an embodiment of the present invention may include a silicon additive represented by the following Chemical Formula 1 to increase the selectivity for the silicon nitride film compared to the silicon oxide film.

[Formula 1]

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 including 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 hydrophilic functional groups.

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

In addition, alkoxy as used herein means both an -O-(alkyl) group and an -O-(unsubstituted cycloalkyl) group, which is a straight chain or ground hydrocarbon having one or more ether groups 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, but is not limited thereto.

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

C _a -C _b functional group as used herein refers to a functional group having a to b carbon atoms. For example, C _a -C _b alkyl means a saturated aliphatic group including straight-chain alkyl and pulverized alkyl having a to b carbon atoms. The straight chain or pulverized alkyl has 10 or fewer carbon atoms in its main chain (eg, C ₁ -C ₁₀ straight chain, C ₃ -C ₁₀ pulverized), preferably 4 or less, more preferably 3 or less carbon atoms 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 -It can be octyl.

Aryl herein refers to an unsaturated aromatic ring comprising a single ring or multiple rings (preferably 1 to 4 rings) joined or covalently bonded to each other, unless otherwise defined. Non-limiting examples of aryl include phenyl, biphenyl, o-terphenyl, m-terphenyl, p-terphenyl, 1-naphthyl, 2-naphthyl, 1-anthryl, 2- Antryl, 9-anthryl, 1-phenanthrenyl, 2-phenanthrenyl, 3--phenanthrenyl, 4--phenanthrenyl, 9-phenanthrenyl, 1-pyrenyl, 2- Pyrenyl and 4-pyrrenyl.

Aralkyl is a functional group in the form of aryl in which aryl is substituted with carbon, and is a general term for -(CH ₂ ) _n Ar. Examples of aralkyl are benzyl (-CH ₂ C ₆ H ₅ ) or phenethyl (-CH ₂ CH ₂ C ₆ H ₅ ).

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

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

Non-limiting examples of cycloalkyl containing heteroatoms include 1-(1,2,5,6-tetrahydropyridyl), 1-piperidinyl, 2-piperidinyl, 3-piperidinyl, 4- Morpholinyl, 3-morpholinyl, tetrahydrofuran-2-yl, tetrahydrofuran-3-yl, tetrahydrothien-2-yl, tetrahydrothien-3-yl, 1-piperazinyl and 2 -Piperazinyl and others.

In addition, cycloalkyl containing cycloalkyl or hetero atom may have a form in which cycloalkyl, cycloalkyl containing hetero atom, aryl or heteroaryl is conjugated or covalently linked.

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

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

At this time, according to an embodiment of the present invention, at least one of R ₁ to R ₄ , preferably at least two may be heteroaryl. When two of R ₁ to R ₄ are heteroaryl, the two heteroaryls may be the same or different from each other.

In one embodiment, the heteroaryl attached to the silicon atom may be a hydrophilic heteroaryl functional group having an N-oxide group. When two of R ₁ to R ₄ are heteroaryl, both heteroaryls may have an N-oxide group or only one heteroaryl of the two heteroaryls may have an N-oxide group. When three of R ₁ to R ₄ are heteroaryl, all three heteroaryls may have an N-oxide group or only one or two heteroaryls of the three heteroaryls may have an N-oxide group.

Here, heteroaryl is pyrroyl, pyridyl, oxazolyl, isooxazolyl, triazolyl, thiazolyl, isothiazolyl, pyrazolyl, pyrazolidinyl, oxadiazolyl, thiadiazolyl, imidazolyl, imidazoli Neil, pyridazinyl, triazinyl, piperidinyl, pyrazinyl or pyrimidinyl, but is not limited thereto.

That is, heteroaryl may be defined herein as an aromatic ring containing nitrogen as a hetero atom so as to have an N-oxide group in the ring.

In addition to the examples of heteroaryl described above, heteroaryl may also include heteroaryl in the form of a non-aromatic or aromatic ring conjugated to heteroaryl having an N-oxide group.

For example, heteroaryl in the form of an aromatic ring conjugated to heteroaryl is indolyl, isoindolyl, benzimidazolyl, purinyl, indazolyl, benzooxazolyl, benzoisooxazolyl, benzothiazolyl, qui Nolinyl, isoquinolinyl, quinoxalinyl, acridinyl, sinolinyl, quinazolinyl and phthalazinyl, and the like.

In addition, a heteroaryl having an N-oxide group and a heteroaryl not having an N-oxide group may be simultaneously present in a silicon atom of the silicone additive represented by Chemical Formula 1.

In this case, heteroaryl having no N-oxide group is a functional group in which one or more carbon atoms in aryl are substituted with non-carbon atoms such as nitrogen, oxygen, or sulfur, such as furyl, tetrahydrofuryl, pyrrolyl, pyrrolidinyl, thienyl, Tetrahydrothienyl, oxazolyl, isooxazolyl, triazolyl, thiazolyl, isothiazolyl, pyrazolyl, pyrazolidinyl, oxadiazolyl, thiadiazolyl, imidazolyl, imidazolinyl, pyridyl, pyridyl Dodyl, triazinyl, pyrazinyl, piperazinyl, pyrimidinyl, naphthyridinyl, benzofuranyl, benzothienyl, indolyl, indolinyl, indolinyl, indazolyl, quinolinyl, quinolinyl, Isoquinolinyl, sinolinyl, phthalazinyl, quinazolinyl, quinoxalinyl, pteridinyl, quinuclidinyl, carbazoyl, acridinyl, phenazinyl, phenothizinyl, phenoxazinyl, purinyl, Benzimidazyl and benzothiazolyl and the like, and analogs to which they are conjugated.

That is, the silicon additive used in the silicon substrate etching solution according to an aspect of the present invention includes at least one heteroaryl bonded to a silicon atom, and at least one of the heteroaryls may be a hydrophilic heteroaryl having an N-oxide group. .

Accordingly, the solubility of the silicone additive used in the present invention in an aqueous solution of 85% phosphoric acid at 25°C and 1 bar may be 100 ppm or more. The unit of solubility herein is expressed in ppm, and the solubility of the silicon additive present in the silicon substrate etching solution may vary depending on the type of functional group present in the silicon additive. That is, when a large number of hydrophilic functional groups are present in the silicon additive, most of the silicon additives can be dissolved in the silicon substrate etching solution, but when no hydrophilic functional groups are present in the silicon additive, the amount of the silicon additive dissolved in the silicon substrate etching solution is extremely Will be less.

For example, when the solubility of the silicone additive in the 85% phosphoric acid aqueous solution at 25° C. and 1 bar is less than 100 ppm, it is difficult for the silane compound (eg, silic acid) to exist in a sufficient concentration in the etching solution of the silicon substrate under the etching conditions. Therefore, the etching rate for the silicon oxide film cannot be sufficiently lowered.

At this time, the heteroaryl group bonded to the silicon atom is stably maintained at room temperature with the silicon atom, thereby preventing the concentration of the silane compound (for example, silicic acid) in the etching solution of the silicon substrate from rapidly increasing. In addition, it is possible to prevent the etching rate of the silicon nitride film from being lowered.

It is preferable that the above-described silicon additive is present at 100 to 10,000 ppm in the silicon substrate etching solution. Here, the content of the silicon additive is the amount of the silicon additive dissolved in the silicon substrate etching solution, expressed in units of ppm. For example, the presence of the silicone additive in the silicon substrate etching solution at 100 ppm will mean that the dissolved silicone additive in the silicon substrate etching solution is 100 ppm.

When the silicon additive in the silicon substrate etching solution is less than 100 ppm, the concentration of the silane compound (for example, silicic acid) in the silicon substrate etching solution is excessively low under the etching conditions, thereby increasing the selectivity to the silicon nitride film compared to the silicon oxide film. The effect may be incomplete.

On the other hand, when the silicon additive in the silicon substrate etching solution exceeds 10,000 ppm, the amount of the silane compound (e.g., silicic acid) in the silicon substrate etching solution is excessively increased under etching conditions to etch the silicon nitride film as well as the silicon oxide film. Problems that slow down to speed can occur. In addition, the silane compound in the etch solution can act as a source of silicon-based particles by itself.

The silicon substrate etching solution according to an embodiment of the present invention may further include a fluorine-containing compound to compensate for the etching rate of the silicon nitride film that is lowered by using a silicon additive and to improve the efficiency of the overall etching process. .

Fluorine-containing compounds herein refer 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 hydrogen fluoride.

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

For example, the fluorine-containing compound may be a compound in which an alkylammonium and a fluorine anion are ion-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 alkylpyrrolium, alkylimidazolium, alkylpyrazolium, alkyloxazolium, alkylthiazolium, alkylpyridinium, alkylpyrimidinium, alkylpyridazinium, alkylpyra Organic cations and fluorophosphates, fluoroalkyl-fluorophosphates, fluoroborates and fluoroalkyl-fluores selected from zinium, alkylpyrrolidinium, alkylphosphonium, alkylmorpholinium, and alkylpiperidinium The fluorine-based anion selected from roborate may be an ionic liquid in an ion-bonded form.

A fluorine-containing compound provided in an ionic liquid form as compared to hydrogen fluoride or ammonium fluoride commonly used as a fluorine-containing compound in a silicon substrate etching solution has a high boiling point and decomposition temperature, and decomposes during an etching process performed at a high temperature Accordingly, there is an advantage that there is little fear of changing the composition of the etching solution.

According to another aspect of the present invention, a method of manufacturing a semiconductor device including an etching process performed using the above-described silicon substrate etching solution is provided.

According to the present manufacturing method, it is possible to manufacture a semiconductor device by performing a selective etching process on the silicon nitride film using the etching solution described above on a silicon substrate including at least a silicon nitride film (SI _x O _y N _z ).

The silicon substrate used in the manufacture of the semiconductor device may include a silicon nitride film (SI _x O _y N _z ), or a silicon oxide film and a silicon nitride film (Si _x N _y , SI _x O _y N _z ) at the same time. Also. In the case of a silicon substrate including both a silicon oxide film and a silicon nitride film, the silicon oxide film and the silicon nitride film may be alternately stacked or stacked in different regions.

The method of manufacturing a semiconductor device according to the present invention requires selective removal of a silicon nitride film without loss of a silicon oxide film during a device separation process of a flash memory device, a device separation process of a DRAM device, or a diode formation process in a phase change memory device. It may be performed by using the silicon substrate etching solution described above in the process step.

Hereinafter, specific embodiments of the present invention are presented. However, the examples described below are only for specifically illustrating or explaining the present invention, and the present invention is not limited thereto.

Composition of silicon substrate etching solution

Example 1

Phosphoric acid 85% by weight, a silicon additive represented by the following formula (2) 1,000 ppm and the remaining amount of water were mixed to prepare a silicon substrate etching solution.

[Formula 2]

Example 2

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that the silicone additive represented by Chemical Formula 3 below was used.

[Formula 3]

Example 3

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that the silicone additive represented by Chemical Formula 4 below was used.

[Formula 4]

Example 4

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that the silicone additive represented by Chemical Formula 5 below was used.

[Formula 5]

Example 5

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that the silicone additive represented by Chemical Formula 6 below was used.

[Formula 6]

Example 6

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that the silicone additive represented by Chemical Formula 7 below was used.

[Formula 7]

Comparative Example 1

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that no silicone additive was used.

Comparative Example 2

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that the silicone additive represented by Chemical Formula 8 below was used.

[Formula 8]

Comparative Example 3

A silicon substrate etching solution was prepared in the same manner as in Example 1, except that the silicone additive represented by Chemical Formula 9 below was used.

[Formula 8]

Experimental Example 1

In order to measure the solubility of the silicone additive in the silicon substrate etching solution having a composition according to each example and comparative example, it was measured by ICP at 25°C and 1 bar. The measurement results are shown in Table 1 below.

division Content of dissolved silicone additive in etching solution
(ppm) Example 1 1000 Example 2 997 Example 3 998 Example 4 1000 Example 5 1000 Example 6 999 Comparative Example 1 - Comparative Example 2 1000 Comparative Example 3 25

Referring to the results of Table 1, unlike Comparative Example 3, the silicone additives used in Examples 1 to 6 include a hydrophilic heteroaryl group bonded to a silicon atom to ensure sufficient solubility in the silicon substrate etching solution. It can be seen that the etch rate for the silicon oxide film can be lowered by increasing the concentration of the silane compound (eg, silicic acid) in the silicon substrate etching solution.

Experimental Example 2

After etching the silicon substrate etching solution having a composition according to each of Examples and Comparative Examples to 165° C., a 500 oxide thick silicon oxide layer and a silicon nitride film were immersed in a heated etching solution for 3 minutes to etch. At this time, the pH of the etching solution heated to 165 ℃ was measured in the range of 2.0 ~ 2.5.

The thickness of the silicon oxide film and the silicon nitride film before and after etching was measured using an ellipsometry (Nano-View, SE MG-1000; Ellipsometery), and the measurement result is an average value of five measurement results. The etching rate is a value calculated by dividing the thickness difference between the silicon oxide film and the silicon nitride film before and after etching by the etching time (3 minutes).

In addition, after the etching was completed, the etching solution was analyzed by a particle size analyzer to measure the average diameter of silicon-based particles present in the etching solution.

The measured etching rate and the average diameter of the silicon-based particles in the etching solution are shown in Table 2 below.

division Silicone particle
Average diameter (μm) Silicon oxide film
Etching speed (Å/min) Silicon nitride film
Etching speed (Å/min) Example 1 <0.01 0.41 91.12 Example 2 <0.01 0.05 89.77 Example 3 <0.01 0.37 92.07 Example 4 <0.01 0.40 92.11 Example 5 <0.01 0.38 91.74 Example 6 <0.01 0.32 92.11 Comparative Example 1 - 5.79 92.19 Comparative Example 2 3.0> 2.79 91.03 Comparative Example 3 <0.01 5.47 93.33

Referring to the results of Table 1, compared to the case where a separate silicone additive is not used as in Comparative Example 1, a silicon oxide film is used when a silane compound capable of increasing the silicon concentration in the etching solution is used as a silicone additive as in Comparative Example 2 As a result, it is possible to improve the etch selectivity for the silicon nitride film compared to the silicon oxide film by lowering the etch rate for. However, when using a silane compound in which an ethoxy group is bonded to a silicon atom as a silicon additive as in Comparative Example 2, it can be confirmed that silicon-based particles have grown.

On the other hand, in the case of the silicon additive used in Comparative Example 3 can not be sufficiently dissolved into the silicon substrate etching solution, it can be seen that the effect of improving the etching selectivity to the silicon nitride film is negligible.

Experimental Example 3

The silicon substrate etching solution having the composition according to each of the Examples and Comparative Examples was heated at 165°C for 0.5 hours, 1 hour, and 2 hours, respectively, and then a 500 Å thick silicon oxide layer and a silicon nitride film were heated and etched. The solution was etched by immersion for 3 minutes. At this time, the pH of the etching solution heated to 165 ℃ was measured in the range of 2.0 ~ 2.5.

The thickness of the silicon oxide film and the silicon nitride film before and after etching was measured using an ellipsometry (Nano-View, SE MG-1000; Ellipsometery), and the measurement result is an average value of five measurement results. The etching rate is a value calculated by dividing the thickness difference between the silicon oxide film and the silicon nitride film before and after etching by the etching time (3 minutes).

The etching rates measured using the silicon substrate etching solutions having different heating times are shown in Tables 3 to 5 below.

0.5 hour heating Silicon oxide film
Etching speed (Å/min) Silicon nitride film
Etching speed (Å/min) Example 1 0.41 91.20 Example 2 0.05 89.19 Example 3 0.37 92.10 Example 4 0.40 92.06 Example 5 0.38 91.14 Example 6 0.34 91.51 Comparative Example 1 5.79 92.72 Comparative Example 2 1.87 91.00 Comparative Example 3 4.59 93.05

1 hour heating Silicon oxide film
Etching speed (Å/min) Silicon nitride film
Etching speed (Å/min) Example 1 0.40 91.21 Example 2 0.03 89.18 Example 3 0.35 92.07 Example 4 0.34 92.09 Example 5 0.36 91.22 Example 6 0.32 91.63 Comparative Example 1 5.87 92.55 Comparative Example 2 1.29 91.11 Comparative Example 3 3.67 93.07

2 hours heating Silicon oxide film
Etching speed (Å/min) Silicon nitride film
Etching speed (Å/min) Example 1 0.34 91.20 Example 2 0.03 89.19 Example 3 0.34 92.10 Example 4 0.33 92.06 Example 5 0.35 91.14 Example 6 0.31 91.54 Comparative Example 1 5.79 92.72 Comparative Example 2 0.82 91.00 Comparative Example 3 3.51 93.05

As the heating time of the silicon substrate etching solution increases, the content of the silane compound (silic acid) in the silicon substrate etching solution gradually increases, and accordingly, the etching rate for the silicon oxide film gradually decreases, and the silicon nitride film is compared to the silicon nitride film. It can be seen that the etch selectivity is improved.

As described above, one embodiment of the present invention has been described, but those skilled in the art can add, change, delete, or add elements within the scope of the present invention described in the claims. It will be said that the present invention can be variously modified and changed by the like, and this is also included within the scope of the present invention.

Claims (8)

Aqueous phosphoric acid solution; And
A silicone additive represented by Formula 1 below;
Containing,
Silicon substrate etching solution:
[Formula 1]

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 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, Selected from alkoxy, amide, ester, acid anhydride, acyl halide, cyano, carboxyl and azole,
At least one of R ₁ to R ₄ is heteroaryl,
The solubility of the silicone additive in aqueous 85% phosphoric acid solution at 25° C. and 1 bar is 100 ppm or more.
According to claim 1,
The heteroaryl has an N-oxide group,
Silicon substrate etching solution.
According to claim 2,
The heteroaryl is pyrroyl, pyridyl, oxazolyl, isooxazolyl, triazolyl, thiazolyl, isothiazolyl, pyrazolyl, pyrazolidinyl, oxadiazolyl, thiadiazolyl, imidazolyl, imidazolinyl , Comprising pyridazinyl, triazinyl, piperidinyl, pyrazinyl and pyrimidinyl,
Silicon substrate etching solution.
According to claim 1,
The silicon additive in the silicon substrate etching solution is included in 100 to 10,000 ppm,
Silicon substrate etching solution.
According to claim 1,
The silicon substrate etching solution is to etch a single film made of a silicon oxide film or a multilayer film including a silicon oxide film and a silicon nitride film at the same time.
Silicon substrate etching solution.
According to claim 1,
The silicon substrate etching solution further comprises 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,
The silicon substrate etching solution further includes a fluorine-containing compound having an ion-bonded form of an organic cation and a fluorine anion,
Silicon substrate etching solution.
A method of manufacturing a semiconductor device including a “etching” process performed using the “silicon substrate etching solution” according to claim 1.