TWI858437B - Silicon nitride film etching composition and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a silicon nitride film etching composition and a preparation method thereof. The silicon nitride film etching composition according to the present invention may contain phosphoric acid, hydrogen fluoride, silicate ions and water. The silicon nitride film etching composition of the present invention can provide excellent effects of maintaining excellent etching selectivity ratio, high etching rate of silicon nitride film, and suppressing generation of particles after the etching process.

Description

Silicon nitride film etching composition and preparation method thereof

The present invention relates to an etching composition, and more particularly to a wet etching composition for selectively etching a silicon nitride film.

Silicon nitride (Si ₃ N ₄ ) is a physically and chemically stable thin film in semiconductor manufacturing processes and is widely used as an insulating film, dielectric film, protective film, etch stop film, etc. in semiconductor devices. In particular, in flash memory devices, silicon oxide film (SiO ₂ ) and silicon nitride film (SiN _x ) have a structure in which a single layer or more layers are alternately stacked. However, with the miniaturization and high integration of semiconductor devices, in order to solve the interference phenomenon between devices, etching compositions that can improve the etching selectivity of each film are currently being developed.

In the wet etching process for removing the silicon nitride film, an etching solution prepared by heating a phosphoric acid aqueous solution to 157 to 165°C is generally widely used. The etching rate of the silicon nitride film is about 20 to 50 times faster than that of the silicon oxide film. Therefore, when pure phosphoric acid is used as the etching solution, the silicon oxide film is weakly etched, resulting in micro-pattern defects, and the etching selectivity (nitride film/oxide film) is about 25 to 50:1, which is very low.

In order to prevent the reduction of etching selectivity, silicon compounds and the like are used as additives in phosphoric acid, but a large number of particles are generated on the wafer after the etching process, which has the problem of reducing the reliability of semiconductor devices. In addition, when an etching solution containing inorganic acids such as fluoric acid, sulfuric acid, and nitric acid is used as another method to ensure etching selectivity, there is a problem that the etching selectivity decreases over time.

Therefore, it is necessary to develop an etching composition that can increase the etching speed of silicon nitride films, improve the etching selectivity, and minimize the generation of particles during the etching process.

The technical problem to be solved by the present invention is to provide a silicon nitride film etching composition with excellent etching selectivity and minimizing the generation of particles during the etching process.

The technical problems to be solved by the present invention are not limited to the technical problems described above. Technical personnel in this field can clearly understand other technical problems not described below.

In order to solve the above technical problems, the silicon nitride film etching composition of the present invention may include phosphoric acid, hydrogen fluoride, silicate ions and water.

Based on 100 mol parts of phosphoric acid, it may contain 0.5 to 1.7 mol parts of hydrogen fluoride, 0.1 to 0.3 mol parts of silicate ions, and 90 to 100 mol parts of water.

The silicate ion may be at least one selected from SiO ₃ ^2- and SiO ₄ ^4- . Specifically, the silicate ion may be SiO ₃ ^2- , but is not limited thereto.

The silicate ions may be formed by ionization of an organic silicon compound represented by the following chemical formula 1.

In the chemical formula 1, _R1 to _R3 are each independently hydrogen, C1 to C3 alkyl, acetyl or vinyl, and _R4 is hydrogen, C1 to C3 alkyl, vinyl, C1 to C3 alkoxy, acetyloxy or vinyloxy.

The organic silicon compound may be at least one selected from tetramethyl orthosilicate, tetraethyl orthosilicate (TEOS), isopropyl orthosilicate, triacetoxymethylsilane and triacetoxyvinylsilane. Specifically, the organic silicon compound may be tetraethyl orthosilicate (TEOS), but is not limited thereto.

Next, in order to solve the above technical problems, the present invention can provide a method for preparing a silicon nitride film etching composition, comprising: a step of mixing an organic silicon compound and a hydrogen fluoride aqueous solution to prepare a mixed solution; a step of adding the mixed solution to a phosphoric acid aqueous solution; and a step of heating the phosphoric acid aqueous solution to which the mixed solution is added.

The temperature for heating the phosphoric acid aqueous solution to which the mixed solution is added may be 50 to 100°C.

The silicon nitride film etching composition may contain silicate ions formed by ionization of the organic silicon compound.

The silicate ion may be at least one selected from SiO ₃ ^2- and SiO ₄ ^4- . Specifically, the silicate ion may be SiO ₃ ^2- , but is not limited thereto.

And in order to solve the above technical problems, the present invention may include a process of wet etching a silicon nitride film using the silicon nitride film etching composition.

When the silicon nitride film etching composition is used, the etching rate of the silicon nitride film can reach above 16.6nm/min.

When the silicon nitride film etching composition is used, the etching selectivity of the silicon nitride film relative to the silicon oxide film can reach ∞.

According to the above-mentioned present invention, the silicon nitride film etching composition of the present invention comprising phosphoric acid, hydrogen fluoride, silicate ions and water has an etching selectivity of ∞, maintains excellent, has a high etching speed for the silicon nitride film, and has excellent effects of suppressing the generation of particles during the etching process.

FIG1 is a flow chart showing a method for preparing a silicon nitride film etching composition according to an embodiment of the present invention; FIG2 is a curve diagram showing the UV/vis absorbance of a silicon nitride film etching composition and a mixture of ammonium molybdate according to an experimental example of the present invention; FIG3 is a curve diagram showing the maximum UV/vis absorbance and its trend curve related to the concentration of a silicon nitride film etching composition and a mixture of ammonium molybdate according to an experimental example of the present invention.

The following is a more detailed description of the preferred embodiments of the present invention with reference to the attached figures. However, the purpose is not to limit the present invention to a specific disclosure method, and it should be understood to include all changes, equivalents and substitutes included in the idea and technical scope of the present invention. On the contrary, the embodiments introduced here are provided to make the disclosed content sufficient and complete, and to fully convey the idea of the present invention to technical personnel in this field.

In the absence of other different definitions, all terms used in the text, including technical or scientific terms, have the same meaning as the general understanding of ordinary technicians in the technical field to which the invention belongs. Terms defined in commonly used dictionaries should be interpreted as meanings consistent with the context of the relevant technology, and should not be interpreted as ideal or overly formal meanings without clear definitions in this application. For example, the terms "oxide film" and "nitride film" used in the present invention can be understood as "silicon oxide film" and "silicon nitride film", respectively.

In addition, if there is no other definition in the content, the singular expression should be understood to include the plural expression. Moreover, the terms such as "including" or "having" are intended to specify the existence of the features, numbers, steps, constituent elements or their combinations described in the specification, and do not pre-exclude the existence or additional possibility of one or more other features, numbers, steps, constituent elements or their combinations.

Furthermore, in the following description of the present invention, if it is judged that the specific description of the relevant known functions or structures may confuse the main purpose of the present invention, the detailed description will be omitted.

Silicon nitride film etching composition

The silicon nitride film etching composition of the present invention may include phosphoric acid, hydrogen fluoride, silicate ions and water. In particular, the etching composition of the present invention may include silicate ions as a silicon oxide film etching inhibitor. Furthermore, the etching composition of the present invention may include hydrogen fluoride as an etching rate enhancer.

The silicate ions contained in the etching composition of the present invention can act as a silicon oxide film etching inhibitor to inhibit the etching of the silicon oxide film.

Furthermore, the silicate ions contained in the etching composition of the present invention not only improve the etching selectivity of the silicon nitride film, but also play an effective role in suppressing the particles generated during the etching process. The wet etching method using silicon compounds used in the past has the disadvantage of forming a large number of foreign bodies on the wafer surface. This is because when etching the silicon nitride film and/or silicon oxide film using an etching process, especially a wet etching process, the extremely small particles generated on the wafer substrate act as growth nuclei and grow into large-sized particles. In contrast, the silicate ions contained in the etching composition of the present invention do not act as growth nuclei, so they have the effect of suppressing the growth of the foreign bodies in the etching process.

The silicate ion is a single and/or double bond between a silicon atom and an oxygen atom, i.e., a divalent or tetravalent anion having at least three Si-O and/or Si=O bonds, and can be, for example, at least any one selected from metasilicate ions (SiO ₃ ^2- ), orthosilicate ions (SiO ₄ ^4- ), and combinations thereof. In a specific example, the silicate ion can be metasilicate ions (SiO ₃ ^2- ), but is not limited thereto.

In particular, the content of the silicate ions contained in the etching composition of the present invention may be 0.1 to 0.3 mol parts based on 100 mol parts of phosphoric acid. When the silicate ions contained in the etching composition of the present invention are within the above content range, the etching composition of the present invention can effectively inhibit the etching of the silicon oxide film and can significantly reduce the foreign matter generated in the etching process, especially the wet etching process. When the amount of the silicate ions is less than 0.2 mol parts, the etching energy of the nitride film and/or the oxide film can be reduced, and when it exceeds 0.3 mol parts, the etching energy of the oxide film is increased, thereby reducing the etching selectivity. However, the content of the silicate ions is not limited to the range described above and can be appropriately adjusted according to the required etching properties.

The silicate ions may be generated from an organic silicon compound. Specifically, the silicate ions may be formed by ionization of the organic silicon compound in the presence of hydrogen fluoride.

The organic silicon compound can be represented by the following chemical formula 1.

In the chemical formula 1, _R1 to _R3 can be independently hydrogen, C1 to C3 alkyl, acetyl or vinyl, and _R4 can be hydrogen, C1 to C3 alkyl, vinyl, C1 to C3 alkoxyacetyloxy or vinyloxy.

Specifically, the organic silicon compound may be at least one selected from tetramethyl orthosilicate, tetraethyl orthosilicate (TEOS), isopropyl orthosilicate, triacetoxymethylsilane and triacetoxyvinylsilane. More specifically, the organic silicon compound may be tetraethyl orthosilicate (TEOS).

The organosilicon compound can break the covalent bonds in the molecule to form silicate ions by externally applied energy, such as heat energy, physical energy and/or chemical energy, in the presence of hydrogen fluoride. Specifically, the energy applied to the organosilicon compound can be sufficient to break or ionize the covalent bonds between carbon and oxygen (C-O) and/or the covalent bonds between silicon and carbon (Si-C) in the molecule of the organosilicon compound, such as heat energy, light energy, kinetic energy, etc. More specifically, the external energy can be supplied by heating, ultrasonic treatment, microwave treatment, etc. to ionize the organosilicon compound, but it is not limited thereto.

Furthermore, the etching composition of the present invention may include the silicate ions used as the etching inhibitor of the silicon oxide film and hydrogen fluoride used as the etching rate enhancer. The hydrogen fluoride, as an inorganic acid, can enhance the etching rate of the silicon oxide film and the silicon nitride film.

Regarding the content of hydrogen fluoride contained in the etching composition of the present invention as a nitride film etching rate enhancer in order to ensure an excellent etching rate of the silicon nitride film, 0.5 to 1.7 mol parts can be contained based on 100 mol parts of phosphoric acid. If the amount of hydrogen fluoride is less than 0.9 mol parts, the addition effect on etching energy cannot be obtained at all. If the amount exceeds 1.2 mol parts, the etching rate of the oxide film increases, resulting in a decrease in etching selectivity, or silicon particles condense and adhere to the wafer.

Method for preparing etching composition

FIG1 is a flow chart showing a method for preparing a silicon nitride film etching composition according to an embodiment of the present invention.

Referring to FIG. 1 , the method for preparing the silicon nitride film etching composition of the present invention may include the steps of mixing an organic silicon compound and a hydrogen fluoride aqueous solution to prepare a mixed solution; adding the mixed solution to a phosphoric acid aqueous solution; and heating the phosphoric acid aqueous solution to which the mixed solution is added.

First, an organic silicon compound and a hydrogen fluoride aqueous solution may be mixed to prepare a mixed solution. The mixed solution may be a homogeneous mixture formed by uniformly mixing an organic silicon compound and a hydrogen fluoride aqueous solution at room temperature.

In order to improve the miscibility of the mixed solution, or to ionize the organic silicon compound in the mixed solution, the organic silicon compound and the aqueous hydrogen fluoride solution may be mixed by mixing, stirring, heating, ultrasonication, microwave, and a combination thereof. For example, the mixed solution may be heated to a temperature of 50 to 200°C and/or treated with a microwave of 100 to 2000W, but is not limited thereto.

In the prepared mixed solution, the organic silicon compound can be ionized to generate silicate ions. The organic silicon compound can be ionized in the presence of an aqueous hydrogen fluoride solution, i.e., fluoric acid, and can react with highly reactive fluorine ions contained in the fluoric acid to generate silicate ions. Furthermore, the organic silicon compound can be ionized by energy applied from the outside, such as thermal energy, kinetic energy, etc. The ionization process of the organic silicon compound may specifically refer to the reaction with fluorine ions and/or the breaking of the covalent bonds between carbon-oxygen bonds (C-O) and/or covalent bonds between silicon-carbon (Si-C) in the organic silicon compound by externally applied energy to form single and/or double bonds between silicon atoms and oxygen atoms, i.e., divalent or tetravalent anions with at least three Si-O and/or Si=O bonds, i.e., silicate ions.

The silicate ion is a single and/or double bond between a silicon atom and an oxygen atom, i.e., a divalent or tetravalent anion having at least three Si-O and/or Si=O bonds, and can be, for example, at least one selected from metasilicate ions (SiO ₃ ^2- ), orthosilicate ions (SiO ₄ ^4- ), and combinations thereof. In a specific example, the silicate ion can be metasilicate ions (SiO ₃ ^2- ), but is not limited thereto.

The organic silicon compound can be represented by the following chemical formula 1.

In the chemical formula 1, _R1 to _R3 are independently hydrogen, C1-3 alkyl, acetyl or vinyl, and _R4 is hydrogen, C1-3 alkyl, vinyl, C1-3 alkoxy, acetyloxy or vinyloxy.

Specifically, the organic silicon compound may be at least one selected from tetramethyl orthosilicate, tetraethyl orthosilicate (TEOS), isopropyl orthosilicate, triacetoxymethylsilane and triacetoxyvinylsilane. In a specific example, the organic silicon compound may be tetraethyl orthosilicate (TEOS), but is not limited thereto.

The hydrogen fluoride aqueous solution may be selected in a concentration range of 10 to 100 wt%, more specifically, in a concentration range of 40 to 60 wt%. In one example, the hydrogen fluoride aqueous solution may be a 50 wt% aqueous solution, but is not limited thereto.

The organic silicon compound and the aqueous hydrogen fluoride solution can be mixed at a quality ratio of 1:1 to 1:5 at room temperature. The mixing ratio of the organic silicon compound and the aqueous hydrogen fluoride solution can be provided in the amount of hydrogen fluoride required for the organic silicon compound to ionize and generate a sufficient amount of silicate ions, for example, the aqueous hydrogen fluoride solution can be equal to and/or in excess of the organic silicon compound. If the amount of the organic silicon compound is more than the aqueous hydrogen fluoride solution, the residual compounds in the organic silicon compound that are not ionized may cause the problem of foreign matter being left on the wafer during the etching process. More specifically, the mixing ratio of the organic silicon compound and the aqueous hydrogen fluoride solution can be used at a quality ratio of 1:1 to 1:2. In a specific example, a quality ratio of 1:1 can be used, but it is not limited to this.

Afterwards, the mixed solution can be added to the phosphoric acid aqueous solution. The mixed solution and the phosphoric acid aqueous solution can be mixed at room temperature at a mass ratio of 0.1:100 to 1:100. The silicate ions and hydrogen fluoride in the mixed solution can be added to the phosphoric acid as the main etching material in the wet etching process as an additive. The silicate ions have the effect of inhibiting the etching of the silicon oxide film, and the hydrogen fluoride can be an additive with the effect of increasing the etching rate. When the silicate ions and the hydrogen fluoride are included in the phosphoric acid aqueous solution at a mass ratio within the range, it has the characteristics of effectively improving the etching selectivity while being able to inhibit the formation of particles. Specifically, the mixing ratio of the mixed solution and the phosphoric acid aqueous solution can be used at a mass ratio of 0.4:100 to 0.9:100, and in a specific example can be used at a mass ratio of 0.8:100, but is not limited thereto.

After the mixed solution is added to the phosphoric acid aqueous solution, in order to ionize the organic silicon compound in the solution, a physical mixing method such as mixing, stirring, heating, ultrasonication, microwave, and a combination thereof may be further used during the addition. For example, the solution may be heated to a temperature of 50 to 200°C, and may also be treated with a microwave of 100 to 2000W, but is not limited thereto.

The concentration of the phosphoric acid (H ₃ PO ₄ ) aqueous solution may be in the range of 1 to 99 wt %, specifically, in the range of 50 to 90 wt %. In a specific example, the concentration of the phosphoric acid (H ₃ PO ₄ ) aqueous solution may be 85 wt %, but is not limited thereto.

When the silicate anion is included in the etching composition, its solubility is not limited to 85% of a phosphoric acid (H ₃ PO ₄ ) aqueous solution, and other functional additives may be further added.

Afterwards, the phosphoric acid aqueous solution to which the mixed solution is added may be heated. Furthermore, in order to simultaneously perform a wet etching process, a wafer having a nitride film and/or an oxide film formed thereon may be immersed in the mixed solution and heated.

The heating temperature may be 50°C to 100°C, and the heating temperature may be a temperature that provides enough energy to break and ionize the covalent bonds between O-C or Si-C in the organic silicon compound molecules. In a specific example, the mixed solution may be heated to a temperature of 80°C, but is not limited thereto.

The organic silicon compound contained in the mixed solution can obtain thermal energy to ionize and form silicate ions in the above-mentioned heating temperature range. Specifically, the silicate ions can be formed by heating the mixed solution containing the organic silicon compound to a temperature of 50 to 100°C, and can be single and/or double bonds of silicon atoms and oxygen atoms, that is, divalent or tetravalent anions with at least three Si-O and/or Si=O bonds.

In particular, in a specific example, the content of hydrogen fluoride contained in the etching composition of the present invention as a nitride film etching rate enhancer in order to ensure an excellent etching rate of the silicon nitride film is preferably 0.5 to 1.7 mol parts based on 100 mol parts of phosphoric acid. If the amount of hydrogen fluoride is less than 0.9 mol parts, the addition effect on etching energy cannot be obtained at all. If the amount exceeds 1.2 mol parts, the etching rate of the oxide film increases, the etching selectivity decreases, or the silicon atoms condense and adhere to the wafer.

Furthermore, in order to maintain an excellent etching selectivity, the content of silicate ions included in the etching composition of the present invention as an oxide film etching inhibitor is preferably 0.1 to 0.3 mol parts based on 100 mol parts of phosphoric acid. The amount of silicate ions is 0.2 mol parts, so if it is included too little, the etching energy of the nitride film and/or the oxide film can be reduced, and if it exceeds 0.3 mol parts, the etching energy of the oxide film is increased, thereby reducing the etching selectivity.

<Experimental example: Analysis of silicate ion concentration>

FIG. 2 is a graph showing the UV/vis absorbance of a silicon nitride film etching composition and a mixture of ammonium molybdate according to an experimental example of the present invention. And FIG. 3 is a graph showing the maximum UV/vis absorbance and its trend related to the concentration of a silicon nitride film etching composition and a mixture of ammonium molybdate according to an experimental example of the present invention.

Referring to Figures 2 and 3, a colorimetric determination method was used to quantitatively analyze the concentration of silicate ions in the silicon nitride film etching composition of the present invention. The silicon nitride film etching composition prepared by the method of the embodiment and ammonium molybdate were mixed and reacted to prepare a mixture having a silicate concentration of 10, 25, and 50 ppm. Afterwards, the absorbance of the mixture was measured using a UV/vis spectrophotometer, and the maximum absorbance of the mixture at a concentration of 10, 25, and 50 ppm was measured respectively. The concentration of silicate ions contained in the silicon nitride film etching composition of the present invention was calculated by this.

<Preparation Examples 1-5: Preparation of Silicon Nitride Film Etching Composition Containing Silicate Ions>

First, 2.0 g of 50 wt% fluoric acid aqueous solution and 2.0 g of tetraethyl orthosilicate (TEOS) were mixed at room temperature to prepare a mixed solution. Afterwards, the mixed solution was added to 500 g of 85 wt% phosphoric acid aqueous solution to prepare a silicon nitride film etching composition containing silicate ions (Preparation Example 1). Preparation Examples 2 to 5 also prepared etching compositions using 50 wt% fluoric acid aqueous solution and other amounts of TEOS in the same manner as Preparation Example 1. Table 1 summarizes the compositions of the etching compositions contained in Preparation Examples 1 to 5 of the present invention.

<Preparation Examples 6-8: Preparation of Silicon Nitride Film Etching Compositions Containing No Silicate Ions>

First, the etching composition of Preparation Example 6 adopts an 85wt% phosphoric acid aqueous solution. And, the etching composition of Preparation Example 7 is prepared by mixing 0.5g of solid metasilicic acid ( _{H2SiO3 )} and 2.5g of 35wt% hexafluorosilicic acid ( _H2SiF6 ) aqueous solution at room temperature to prepare a mixed solution, and adding it to 500g of 85wt% phosphoric acid aqueous solution. Thereafter, the etching composition of Preparation Example ₈ is prepared by mixing 0.5g of solid metasilicic acid ( _{H2SiO3 )} to 2.5g of 50wt% fluoric acid aqueous solution at room temperature to prepare a mixed solution, and then adding it to 500g of 85wt% phosphoric acid aqueous solution. Table 2 summarizes the compositions of the etching compositions included in Preparation Examples 6 to 8 of the present invention.

<Example: Experimental results on etching selectivity and particle generation corresponding to the composition of the etching composition>

In Table 3, E/R is an abbreviation of etching rate (Etchrate). In the etching process performed to measure the etching rate (E/R), the etching composition shown in Table 3 was used to wet-etch the etched object (silicon oxide film and/or silicon nitride film). In the wet etching process, the wafer formed with the nitride film and the oxide film was immersed in the etching composition of the present invention and heated to 80°C, and the etching rate and etching selectivity were measured over time. The formula for calculating the etching rate (E/R) is shown in the following formula 1.

[Formula 1] Etching rate (E/R) = {initial film thickness (nm) - film thickness after etching (nm)} / etching processing time (min)

The formula for calculating the etching selectivity is shown in the following formula 2.

[Formula 2] Etching selectivity = silicon nitride film etching rate (nm/min) / silicon oxide film etching rate (nm)

Regarding the detection of the presence of the aforementioned particles, the wafer substrate surface is observed using a scanning electron microscope (SEM), and particles with a size of 0.3nm or more found using a Zeta-Potential Analyzer (microscopic analysis) are identified as particles.

Referring to Table 3, the etching rates of the nitride film corresponding to the content of silicate ions (SiO ₃ ^2- ) contained in the etching composition can be compared through Examples 1 to 3. The etching compositions of Examples 1, 2 and 3 contain 0.221, 0.243 and 0.265 molar parts of silicate ions, respectively, and the etching rates of the nitride film using them are measured to be 20, 22.4 and 16.8 nm/min. That is, the etching rate of the oxide film of the etching composition of Example 2 containing 0.243 molar parts of silicate ions is 0 nm/min and the etching rate of the nitride film is 22.4 nm/min, and the etching selectivity is calculated to be ∞, showing the best results in the etching characteristics of the silicon nitride film. However, the etching speed of the oxide film of the etching compositions of Examples 1 to 3 was measured to be 0 nm/min. The etching composition of the present invention can reduce the etching speed of the oxide film but increase the etching speed of the nitride film, and the etching selectivity is maintained at ∞. Moreover, no particles were found on the substrate after etching. Therefore, the etching compositions of Examples 1 to 3 have the characteristics of selectively etching only the silicon nitride film when used for a semiconductor pattern including a silicon nitride film and a silicon oxide film, and the etching speed of the silicon nitride film does not decrease.

In addition, Comparative Example 1 is an etching composition that does not contain hydrogen fluoride and/or silicate ions, and only uses 85wt% phosphoric acid. The etching rates of the oxide film and the nitride film of the etching composition of Comparative Example 1 were measured to be 0.2 and 6nm/min, respectively, and the etching selectivity was calculated to be 30. The etching selectivity is significantly lower than that of the etching compositions of Examples 1 to 4. Therefore, compared with the etching composition containing only phosphoric acid, the etching composition containing phosphoric acid, hydrogen fluoride and silicate ions can obtain a significantly higher etching selectivity. However, after the etching process using the etching composition of Comparative Example 1, no particles on the substrate were detected.

In addition, Comparative Example 2 is an etching composition that does not contain hydrogen fluoride and/or silicate ions, but contains metasilicic acid (H ₂ SiO ₃ ) and a 35 wt % aqueous solution of hexafluorosilicic acid (H ₂ SiF ₆ ), and Comparative Example 3 is an etching composition that contains hydrogen fluoride and metasilicic acid (H ₂ SiO ₃ ). The etching compositions of Comparative Examples 2 and 3 do not contain hydrogen fluoride and silicate ions (SiO ₃ ^2- ), but contain fluorine and silicon elements. After the etching process was performed using the etching compositions of Comparative Examples 2 and 3, the etching rates of the oxide film and the nitride film were measured. The etching rate of the oxide film was 0 nm/min for both Comparative Examples 2 and 3, and the etching rate of the nitride film was 19-20 nm/min. That is, the etching rate using the etching compositions of Comparative Examples 2 and 3 showed a high etching rate similar to that of Examples 1 to 4, and the etching selectivity was excellently maintained at ∞. However, the etching compositions of Comparative Examples 2 and 3 had the problem of a large number of particles on the substrate after the etching process.

According to the above-mentioned present invention, it can be confirmed that the silicon nitride film etching composition of the present invention has excellent characteristics of maintaining the etching selectivity at ∞, not generating particles after the etching process, and having a high etching rate of the silicon nitride film. Therefore, the silicon nitride film etching composition of the present invention can simultaneously suppress the etching of the silicon oxide film and increase the etching rate of the silicon nitride film, and thus has the advantage that both the etching selectivity and production can be ensured.

The embodiments of the present invention disclosed in this specification and the attached drawings are only specific examples for the purpose of facilitating understanding, and are not intended to limit the scope of the present invention. The embodiments disclosed herein can also unexpectedly implement gas deformation examples based on the technical ideas of the present invention, which is obvious to ordinary technicians in the technical field to which the present invention belongs.

Claims (11)

A silicon nitride film etching composition, which comprises phosphoric acid, hydrogen fluoride, silicate ions and water, and contains 0.5 to 1.7 moles of hydrogen fluoride and 0.1 to 0.3 moles of silicate ions based on 100 moles of phosphoric acid. The silicon nitride film etching composition as described in claim 1, wherein: based on 100 mol parts of the phosphoric acid, it contains 90 to 100 mol parts of the water. The silicon nitride film etching composition as described in claim 1, wherein: the silicate ion is at least one selected from SiO ₃ ^2- and SiO ₄ ^4- . The silicon nitride film etching composition as claimed in claim 1, wherein: the silicate ions are formed by ionization of an organic silicon compound represented by the following chemical formula 1,

In the chemical formula 1, _R1 to _R3 are independently hydrogen, C1-3 alkyl, acetyl or vinyl, and _R4 is hydrogen, C1-3 alkyl, vinyl, C1-3 alkoxy, acetyloxy or vinyloxy. The silicon nitride film etching composition as described in claim 4, wherein: The organic silicon compound is at least one selected from tetramethyl orthosilicate, tetraethyl orthosilicate (TEOS), isopropyl orthosilicate, triacetoxymethylsilane and triacetoxyvinylsilane. A method for preparing a silicon nitride film etching composition as described in claim 1, comprising: a step of preparing a mixed solution by mixing an organic silicon compound and a hydrogen fluoride aqueous solution; a step of adding the mixed solution to a phosphoric acid aqueous solution; and a step of heating the phosphoric acid aqueous solution to which the mixed solution is added. The silicon nitride film etching composition as described in claim 6, wherein: the temperature at which the phosphoric acid aqueous solution to which the mixed solution is added is heated is 50 to 100°C. The silicon nitride film etching composition as described in claim 6, wherein: the silicon nitride film etching composition contains silicate ions formed by ionization of the organic silicon compound. The silicon nitride film etching composition as described in claim 8, wherein: the silicate ion is at least one selected from SiO ₃ ^2- and SiO ₄ ^4- . A silicon nitride film etching method, comprising: using the etching composition according to any one of claims 1 to 9 to wet-etch at least one selected from a silicon nitride film and a silicon oxide film. A silicon nitride film etching method, wherein: when using the etching composition described in any one of claims 1 to 9, the etching rate of the silicon nitride film reaches more than 16.6nm/min.