KR20180106144A - Etchant composition for etching nitride layer and methods of forming nitride pattern - Google Patents

Abstract

An etchant composition for etching a nitride layer according to the present invention contains: phosphorus acid; a phosphorus containing silane compound containing one silicon (Si) atom and one phosphorus (P) atom per molecule; and the remainder consisting of water. A silicon nitride film can be etched at a high selectivity ratio without damaging a silicon oxide film and a polysilicon film by using the etchant composition for etching a nitride layer of the present invention.

Description

TECHNICAL FIELD [0001] The present invention relates to a nitride film etching composition, and a pattern forming method using the same. BACKGROUND ART < RTI ID = 0.0 >

The present invention relates to a nitride film etching composition and a pattern forming method using the same. More particularly, the present invention relates to a nitride film etching composition containing an acid solution and a pattern forming method using the same.

For example, in manufacturing a semiconductor device, various insulating films such as a silicon oxide film and a silicon nitride film may be stacked on a substrate. A selective etching process of the silicon nitride film may be required depending on the necessity of forming various patterns included in the semiconductor device.

In addition to the insulating film, a semiconductor film and a metal film may be formed on the substrate. The semiconductor film or substrate may comprise a semiconductor material such as, for example, polysilicon. Therefore, when the nitride film such as the silicon nitride film is etched, the semiconductor film may be damaged.

For example, Korean Patent Laid-Open No. 10-2005-0003163 discloses a nitrided-film etchant for semiconductor devices including phosphoric acid and hydrofluoric acid. However, when hydrofluoric acid is included in the etching solution, the silicon oxide film is also removed, so that it is difficult to secure a sufficient etch selectivity ratio of the nitride film to the oxide film.

Accordingly, researches are being conducted on etchants that can improve the etching selectivity of the nitride film to the silicon oxide film. However, an etchant having a sufficient etch selectivity to the substrate or the semiconductor film together with the silicon oxide film is not sufficiently developed at present.

Korean Unexamined Patent Application Publication No. 10-2005-0003163 (Oct. 10, 2005)

An object of the present invention is to provide a nitride-based etching composition having an improved etch selectivity to a silicon nitride film.

An object of the present invention is to provide a pattern forming method using a nitride film etching composition having an improved silicon nitride film etching selectivity.

1. Phosphoric acid; Phosphorus-containing silane-based compounds containing one silicon (Si) atom and one phosphorus (P) atom per molecule; And an excess of water.

2. The nitride-based etching composition according to 1 above, wherein the phosphorus-containing silane-based compound comprises a compound represented by the following formula (1)

[Chemical Formula 1]

(Wherein R ₁ is a single bond or an alkyl group having 1 to 10 carbon atoms,

R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms.

3. The method of claim 2, wherein the phosphorus containing silane compound is at least one selected from the group consisting of (2-dimethylphosphatoethyl) trihydroxysilane, (2-dimethylphosphatoethyl) (2-diethylphosphatoethyl) triethoxysilane, (2-diethylphosphatoethyl) trimethoxysilane and (2-diethylphosphatoethyl) trihydroxysilane. Gt; etch < / RTI > composition.

4. The composition of claim 1, wherein,

70 to 99 wt% phosphoric acid; 0.01 to 1% by weight of the phosphorus containing silane compound; And an excess of water.

5. The nitriding film etching composition according to item 1, wherein the silane compound other than the phosphorus-containing silane compound is not contained.

6. forming an oxide film and a polysilicon film on a substrate;

Forming a nitride film in contact with at least one of the oxide film or the polysilicon film; And

A method for pattern formation comprising the step of etching the nitride film using the nitride film etching composition according to any one of claims 1 to 5.

7. The pattern formation method according to 6 above, wherein said oxide film comprises silicon oxide, and said nitride film comprises silicon nitride.

As described above, according to the embodiments of the present invention, the nitride film etching composition can include phosphoric acid and phosphorus (P) -containing silane-based compounds. The phosphorus-containing silane-based compound promotes, for example, the etching rate for the silicon nitride film and suppresses the etching rate for the oxide film such as the silicon oxide film. Further, for example, a semiconductor substrate or a semiconductor film including polysilicon can be protected, and damage to the semiconductor structure can be suppressed.

In addition, since the phosphorus-containing silane compound has a high solubility in the phosphoric acid solution, it is possible to prevent the problem of adverse adsorption of the etching residue on the semiconductor substrate or the oxide film.

The nitride film etching composition according to embodiments of the present invention can be effectively utilized for manufacturing a semiconductor device such as a memory device including, for example, a polysilicon channel.

1 to 3 are sectional views for explaining a pattern forming method according to exemplary embodiments.

The nitride film etching composition according to embodiments of the present invention can be used, for example, for selective etching of a silicon nitride film applied to a semiconductor device or a display device. For example, the nitride film etching composition may be supplied on a structure containing an oxide film, a semiconductor film, and a silicon nitride film at the same time so as to etch only the silicon nitride film with a high selectivity ratio without substantially damaging the oxide film and the semiconductor film.

Hereinafter, embodiments of the present invention will be described in detail. However, this is a preferable example, and the spirit and scope of the present invention are not necessarily limited thereto. In the case where an isomer of the compound represented by the formula used in the present application is present, the compound represented by the formula means a representative formula including the isomer thereof.

≪ Nitride film etching composition >

The nitride film etching composition according to embodiments of the present invention may include phosphoric acid, phosphorus (P) -containing silane compound, and excess water.

Phosphoric acid can be represented, for example, by the formula H ₃ PO ₄ and can act as a major etch component for nitride etch. According to exemplary embodiments, the nitride etch composition may comprise from about 70 to about 99 weight percent phosphoric acid, expressed as percent by weight of the total weight of the composition.

If the content of phosphoric acid is less than about 70 wt%, the overall nitride film etching rate may be lowered. When the content of phosphoric acid is more than about 99 wt%, the etch rate of the oxide film, the semiconductor film, or the metal film as well as the nitride film increases, and the etching selectivity to the nitride film can be reduced.

In some embodiments, phosphoric acid may be included at about 80 to 90 weight percent, taking into account the etch efficiency and etch selectivity of the nitride film.

The phosphorus containing silane-based compound may be included as an etch control agent for suppressing etching damage of a semiconductor film including a silicon oxide film and polysilicon. For example, the surface of the silicon oxide film and the semiconductor film can be passivated by the phosphorus containing silane compound to protect them from etching damage. Therefore, when performing the wet etching process using the nitride film etching composition, the etching selectivity to the silicon nitride film can be remarkably improved.

According to exemplary embodiments, the phosphorus containing silane-based compound may comprise a compound containing one silicon atom and one phosphorus atom per molecule. In some embodiments, the phosphorus containing silane-based compound may comprise a compound represented by the following formula (1).

[Chemical Formula 1]

In the formula (1), R ₁ may be a single bond or an alkyl group having 1 to 10 carbon atoms. As used herein, "single bond" means that silicon atoms (Si) and phosphorus (P) atoms are bonded directly.

R ₂ , R ₃ , R ₄ , R ₅ and R ₆ may each independently be hydrogen or an alkyl group having 1 to 5 carbon atoms.

(2-dimethylphosphatoethyl) trihydroxy silane, (2-dimethylphosphatoethyl) trimethoxysilane, (2-dimethylphosphatoethyl) triethoxysilane, (2- Diethylphosphatoethyl) triethoxysilane, (2-diethylphosphatoethyl) trimethoxysilane, and (2-diethylphosphatoethyl) trihydroxysilane. These may be used alone or in combination of two or more.

In accordance with exemplary embodiments, the phosphorus containing silane-based compound may have a lone electron pair that is richer than other silane compounds, including, for example, a sulfur (S) derived group such as sulfate or a nitrogen (N) derived group such as an amine . Therefore, it is possible to effectively prevent other nucleophiles from approaching the silicon oxide film and / or the semiconductor film by repulsion.

Referring to Formula 1, three hydroxy groups or alkoxy groups may be arranged around a silicon atom. The hydroxy group or the alkoxy group may function as an adsorption hand which is adsorbed on a silicon oxide film or a semiconductor film. Therefore, the passivation of the silicon oxide film or the semiconductor film can be formed by the phosphorus containing silane compound.

Also, one phosphate-derived group may be arranged with R ₁ as a boundary, and the phosphate-derived group may be exposed to the outside to block the nucleophile approaching the silicon oxide film and / or the semiconductor film.

As described above, the passivation through the adsorption of the silicon oxide film and / or the semiconductor film and the blocking of the nucleophile are simultaneously realized by the structure according to the chemical formula (1), so that highly selective non-etching of only the silicon nitride film can be realized.

Further, since the phosphorus-containing silane-based compound contains a phosphate-derived group, it can have stronger affinity for the phosphoric acid solution. Thus, the solubility in the composition can be improved to reduce the generation of particles or etching by-products.

According to exemplary embodiments, the nitride etch composition may comprise about 0.01 to 1% by weight of the phosphorus containing silane-based compound in the total weight of the composition.

When the content of the phosphorus-containing silane compound is less than about 0.01% by weight, sufficient silicon oxide film and damage prevention effect of the semiconductor film may not be realized. If the content of the phosphorus-containing silane compound exceeds about 1% by weight, etching by-products or particles may be generated, and the nitride film etching efficiency may be somewhat lowered.

In some embodiments, the content of the phosphorus containing silane-based compound may be adjusted to about 0.1 to 0.5% by weight in consideration of the nitride film etching selectivity enhancement and the etching efficiency. In one embodiment, the content of the phosphorus containing silane-based compound may be adjusted to about 0.3 to 0.5 wt%.

The excess water included in the nitride film etching composition may include, for example, distilled water or deionized water (DIW).

In some embodiments, the nitride etch composition may further comprise an additive such as the etch enhancer. The etch enhancer may include, for example, a sulfuric acid-based compound or an acid ammonium-based compound. The etch enhancer may be added to improve the overall etch rate of the nitride etch composition and may be added in such a small amount as not to lower the etch selectivity to the nitride layer.

Examples of the sulfuric acid-based compounds include sulfuric acid or methanesulfonic acid. Examples of the ammonium ammonium compounds include ammonium sulfate, ammonium persulfate, ammonium acetate, ammonium phosphate, and the like. These may be used alone or in combination of two or more.

Further, additional components such as a surfactant and a corrosion inhibitor may be further contained within the range not to impair the function of the phosphorus-containing silane compound. remind

In some embodiments, a fluorine-based (e.g., fluorine-containing silane-based) compound may be excluded from the nitriding film etching composition for the protection of the silicon oxide film and the semiconductor film.

In one embodiment, the composition for etching a nitride film contains only the phosphorus-containing silane-based compound described above as the silane-based compound, and may not include other silane compounds (for example oxime silane, silyl sulfate, TEOS, etc.) . The other silane compounds compete with the phosphorus-containing silane-based compound to deteriorate the protection of the semiconductor film and may cause generation of particles due to a decrease in solubility.

As described above, the nitride-based etching composition according to the exemplary embodiments of the present invention may contain phosphorus-containing silane-based compounds together with phosphoric acid. The phosphorus-containing silane compound can selectively increase the etching rate of the nitride film with good solubility. Therefore, a highly reliable wet etching process in which generation of etch residue is suppressed while preventing damage to the semiconductor film and the silicon oxide film can be realized.

≪ Pattern formation method >

1 to 3 are sectional views for explaining a pattern forming method according to exemplary embodiments. The pattern forming method is used to mean a method of forming a nitride film pattern and a method of forming a predetermined structure by removing a nitride film.

Referring to FIG. 1, an oxide film 110, a polysilicon film 120, and a nitride film 130 may be formed on a substrate 100.

The substrate 100 may comprise a semiconductor material such as monocrystalline silicon, monocrystalline germanium, or may be formed to include polysilicon.

According to exemplary embodiments, the oxide film 110 may be formed to include silicon oxide. The oxide film 110 and the polysilicon film 120 may be formed through a chemical vapor deposition (CVD) process, a sputtering process, a physical vapor deposition (PVD) process, an atomic layer deposition (ALD) process,

In FIG. 1, the polysilicon film 120 is formed on the oxide film 110, but the formation order and the position are not particularly limited. For example, the nitride film 130 may be formed so as to contact at least one of the oxide film 110 and the polysilicon film 120.

The nitride film 130 may be formed on the oxide film 110 and the polysilicon film 120. [ According to exemplary embodiments, the nitride film 130 may be formed by a CVD process, a PVD process, a sputtering process, an ALD process, or the like so as to include silicon nitride.

In some embodiments, the nitride layer 130 may be formed to cover the polysilicon layer 120 and the oxide layer 110, as shown in FIG. In some embodiments, the nitride film 130 may be formed to partially cover the polysilicon film 120 and the oxide film 110.

Referring to FIGS. 2 and 3, the nitride film 130 can be at least partially removed. According to exemplary embodiments, the nitride film 130 may be removed using the above-described nitride film etching composition.

As described above, the nitride film etching composition includes phosphoric acid and a phosphorus-containing silane compound, the oxide film 110 containing silicon oxide by the phosphorus containing silane compound, the substrate 100 including the semiconductor material, The damage of the polysilicon film 120 can be suppressed.

Therefore, for example, only the nitride film 130 including silicon nitride is substantially etched, and a high selectivity etching process in which loss of silicon oxide and polysilicon is suppressed can be realized.

In some embodiments, the nitride film pattern 135 formed on the polysilicon film 120 from the nitride film 130 may be formed by the etching process as shown in FIG.

In some embodiments, as shown in FIG. 3, a nitride film pattern (for example, a spacer pattern) formed on the sidewalls of the polysilicon film 120 and the oxide film 110 from the nitride film 130 by the etching process 136 may be formed.

In some embodiments, the nitride film 130 may be entirely removed by the etching process.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. It will be apparent to those skilled in the art that various changes and modifications can be made to the embodiments within the spirit and scope of the appended claims.

Example  And Comparative Example

A nitride film etching composition having the composition and the content (% by weight) shown in Table 1 below was prepared.

division Phosphoric acid
(H ₃ PO ₄ ) Silane compound water
(DIW) A-1 A-2 A-3 A-4 A-5 Example 1 85 0.3 - - - - 14.7 Example 2 85 0.5 - - - - 14.5 Example 3 85 - 0.3 - - - 14.7 Example 4 85 - 0.5 - - - 14.5 Example 5 85 1.0 - - - - 14.0 Example 6 85 - 1.0 - - - 14.0 Comparative Example 1 85 - - - - - 15 Comparative Example 2 85 - - 0.3 - - 14.7 Comparative Example 3 85 - - - 0.3 - 14.7 Comparative Example 4 85 - - - - 0.3 14.7

The specific names of the silane-based compounds are as follows.

A-1: (2-dimethylphosphatoethyl) trihydroxysilane

A-2: (2-diethylphosphatoethyl) triethoxysilane

A-3: 3- (trihydroxysilyl) -1-propanesulfonic acid

A-4: 3-aminopropyl silanetriol

A-5: Preparation of N- (2-aminoethyl) -3-aminopropylsilanetriol

Experimental Example

(1) Measurement of etch rate (E / R) of silicon nitride film (SiN)

A silicon nitride film (SiN) 5000 Å thick wafer was cut into a size of ² × ² cm ² to prepare a sample. The sample was immersed in the compositions of the examples and comparative examples shown in Table 1 at a temperature of 160 ° C. for 3 minutes. Thereafter, the substrate was washed with deionized water (DIW) and dried, and the film thickness was measured by a scanning electron microscope (SEM), and the etching rate (Å / min) was measured.

(2) Silicon oxide film (SiO ₂ ) Etching rate measurement

A silicon oxide film (SiO ₂ ) 400 Å thick wafer was cut into a size of ² × ² cm ² to prepare a sample. The sample was immersed in the compositions of the examples and comparative examples shown in Table 1 at a temperature of 160 ° C. for 30 seconds. Thereafter, the substrate was cleaned with deionized water (DIW) and dried, and the film thickness was measured with an ellipsometer to measure the etching rate (Å / min).

(3) Evaluation of Polysilicon (Poly-Si) Damage.

Poly-Si 2100A thick wafers were cut into a size of 2x2 cm < ² > to prepare samples. The samples were immersed in the compositions of the examples and comparative examples shown in Table 1 at a temperature of 160 DEG C for 30 seconds. Thereafter, the substrate was cleaned with deionized water (DIW) and dried, and the film thickness was measured with an ellipsometer to measure the etching rate (Å / min).

Polysilicon damage was evaluated according to the following criteria.

◎: E / R less than 0.5 Å / min

?: E / R 0.5 to 1.0 A / min

X: E / R exceeding 1.0 Å / min

The measurement results are shown in Table 2 below.

division SiN E / R
(Å / min) SiO ₂ E / R
(Å / min) Etching
Selection ratio Poly-Si damage Example 1 78.7 1.2 65.6 ◎ Example 2 71.5 0.7 102.1 ◎ Example 3 76.1 1.3 58.5 ◎ Example 4 69.8 1.1 63.5 ◎ Example 5 62.5 0.9 69.4 ◎ Example 6 59.3 1.2 49.4 ◎ Comparative Example 1 61.2 2.1 29.1 X Comparative Example 2 57.1 1.9 30.1 △ Comparative Example 3 59.7 3.5 17.1 △ Comparative Example 4 55.7 2.7 20.6 △

Referring to Table 2, in the embodiments including the above phosphorus-containing silane-based compound, a high etch selectivity of the silicon nitride film to the silicon oxide film was obtained without causing damage to the polysilicon. In Examples 1, 2 and 5 in which the phosphorus-containing silane compound containing a trihydroxy silane group was used, in Examples 3, 4, and 6 in which the phosphorus containing silane compound containing the triethoxy silane group was used , It showed an improved etching effect on the silicon oxide film and the polysilicon. Thus, an excellent etching selectivity to the same content was obtained.

In the case of Example 5, the etching rate for the silicon nitride film was decreased as compared with Examples 1 and 2, while the content of the phosphorus containing silane compound was slightly increased. Example 6 Also, the etching rate for the silicon nitride film was decreased as compared with Examples 3 and 4, while the content of the phosphorus containing silane compound was slightly increased.

On the other hand, in the case of Comparative Example 1 in which the silane-based compound was not contained and Comparative Examples 2 to 4 in which the sulfuric acid-based silane compound or aminosilane was used, the etching selectivity ratio was remarkably decreased as the damage to the polysilicon deepened.

100: substrate 110: oxide film
120: polysilicon film 130: nitride film
135, 136: nitride film pattern

Claims (7)

Phosphoric acid;
Phosphorus-containing silane-based compounds containing one silicon (Si) atom and one phosphorus (P) atom per molecule; And
Lt; RTI ID = 0.0 > water. ≪ / RTI >
The nitride-based etching composition according to claim 1, wherein the phosphorus-containing silane-based compound comprises a compound represented by Formula 1:
[Chemical Formula 1]

(Wherein R ₁ is a single bond or an alkyl group having 1 to 10 carbon atoms,
R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently hydrogen or an alkyl group having 1 to 5 carbon atoms.
[3] The method of claim 2, wherein the phosphorus containing silane compound is at least one selected from the group consisting of (2-dimethylphosphatoethyl) trihydroxysilane, (2-dimethylphosphatoethyl) trimethoxysilane, (2-dimethylphosphatoethyl) At least one selected from the group consisting of (2-diethylphosphatoethyl) triethoxysilane, (2-diethylphosphatoethyl) trimethoxysilane, and (2-diethylphosphatoethyl) / RTI >
The composition according to claim 1,
70 to 99 wt% phosphoric acid;
0.01 to 1% by weight of the phosphorus containing silane compound; And
Lt; RTI ID = 0.0 > water. ≪ / RTI >
The nitride-based etching composition according to claim 1, which does not contain any silane compound other than the phosphorus-containing silane-based compound.
Forming an oxide film and a polysilicon film on the substrate;
Forming a nitride film in contact with at least one of the oxide film or the polysilicon film; And
A method for pattern formation comprising the step of etching the nitride film using the nitride film etching composition according to any one of claims 1 to 5.
7. The method of claim 6, wherein the oxide film comprises silicon oxide, and the nitride film comprises silicon nitride.

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