KR102260743B1 - Silicon nitride layer etching composition - Google Patents

Abstract

The present invention relates to a silicon nitride etching composition, and more particularly, by including phosphoric acid, metaphosphoric acid and a silicon-based compound, the silicon nitride film can be etched with a high selectivity compared to the silicon oxide film, and problems such as generation of particles that adversely affect device characteristics It relates to an etching composition for a silicon nitride film having a high selectivity that does not have a silicon nitride film, a method for etching a silicon nitride film using the same, and a method for manufacturing a semiconductor device.

Description

Silicon nitride etching composition {SILICON NITRIDE LAYER ETCHING COMPOSITION}

The present invention relates to a silicon nitride etching composition.

A silicon oxide film (SiO ₂ ) and a silicon nitride film (SiN _x ) are representative insulating films used in a semiconductor manufacturing process. Double silicon nitride films are used as cap layers, spacer layers or hard mask layers in semiconductor devices. The silicon oxide film and the silicon nitride film may be used alone, or one or more silicon oxide films and one or more silicon nitride films may be alternately stacked.

The silicon nitride film is etched using a mixture of high-purity phosphoric acid and deionized water at a high temperature of about 160 °C. However, high-purity phosphoric acid has a problem in that the etching selectivity of the silicon nitride film to the silicon oxide film is low, so it is difficult to apply it to the stacked structure of the silicon nitride film and the silicon oxide film. In addition, since the silicon nitride film etching composition containing phosphoric acid is continuously concentrated by evaporation of moisture at high temperature, and thus affects the etching rates of the nitride film and the oxide film, deionized water must be continuously supplied. However, even a slight change in the amount of supplied pure water may cause defects in the removal of the silicon nitride film, and phosphoric acid itself is corrosive as a strong acid, so it is difficult to handle.

In order to solve the above problems and to improve the etching selectivity of the silicon nitride layer to the silicon oxide layer, a silicon nitride layer etching composition in which silicic acid is dissolved in phosphoric acid may be used. However, the silicon nitride etching composition has a problem in that it is difficult to apply to a process due to the problem of abnormal growth in which particles are generated during etching and the thickness of the silicon oxide film is rather increased.

In addition, a method of controlling the etching selectivity by using a silicon compound containing an oxygen atom directly bonded to silicon may be used, but the etching selectivity of the silicon nitride film compared to the silicon oxide film is not high and particles may be generated, without generating particles. It is necessary to develop an etching composition capable of etching the silicon nitride layer with a high selectivity.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a silicon nitride etching composition that implements a significantly improved etch selectivity with respect to a silicon nitride layer.

Another object of the present invention is to provide a stable silicon nitride etchant composition having little change in the etch rate and etch selectivity for the silicon nitride film even when the etching time is increased or repeatedly used.

Another object of the present invention is to provide a silicon nitride etching composition in which particles are not generated during etching.

Another object of the present invention is to provide a method of etching a silicon nitride layer using a silicon nitride layer etching composition and a method of manufacturing a semiconductor device.

In order to solve the above problems, a first inorganic acid comprising metaphosphoric acid and phosphoric acid; a silicon-based compound selected from compounds represented by the following formula (1); And the remaining amount of water; including, a silicon nitride layer etching composition is provided.

[Formula 1]

[In Formula 1,

R ₁ to R ₄ are each independently hydrogen, hydroxy, halogen, C _{1- 20} alkyl, amino C _{1 - 20} alkyl, C _{2- 20} alkenyl, or C _{1- 20} alkoxy, a sulfonate, sulfate or phosphate, a monovalent substituent comprising the R ₁ to R ₄ is at least one of hydroxy, halogen or C _{1- 20} alkoxy;

L ₁ is an alkylene C _{1- 20} alkyl, -CH ₂ in the alkylene - is optionally replaced by -O-, -S- or -NR'-, wherein R 'is hydrogen or C _{1- 20} alkyl ;

A is an integer selected from 0 to 10;

B is an integer selected from 0 to 4.]

In the silicon nitride layer etching composition according to an embodiment of the present invention, the metaphosphoric acid may be cyclic metaphosphoric acid.

In the silicon nitride layer etching composition according to an embodiment of the present invention, the metaphosphoric acid may be selected from trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, and the like.

In the silicon nitride layer etching composition according to an embodiment of the present invention, the silicon-based compound may be at least one selected from compounds represented by Chemical Formulas 2 and 3 below.

[Formula 2]

[Formula 3]

[In Formula 2 and Formula 3,

R ₁₁ to R ₁₄ and R ₂₁ to R ₂₆ are each independently hydrogen, hydroxy, halogen, C _{1- 7} alkyl, amino-C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7} alkoxy, sulfo carbonate, a sulfate or a monovalent substituent comprising a phosphate, wherein R ₁₁ to R ₁₄ or R ₂₁ to R ₂₆ is at least one of hydroxy, halogen or C _{1- 7} alkoxy;

L ₁ is an alkylene C _{1- 12} alkyl, -CH ₂ in the alkylene - it is optionally replaced by -NR'-, wherein R 'is hydrogen or C _{1- 7} alkyl;

L ₂ and L ₃ are each independently a direct bond or C _{1- 7} alkylene;

A is an integer selected from 0 to 10;

B is an integer selected from 0 to 4.]

In the silicon nitride etching composition in accordance with one embodiment of the invention, the compound represented by the above formula (II) wherein R ₁₁ is hydroxy, halogen, amino C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7} alkoxy; In each of said R ₁₂ to R ₁₄ are independently hydroxy, halogen, C _{1- 7} alkyl, amino-C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7-alkoxy,} wherein at least one of R ₁₂ to R ₁₄ one or more hydroxy, halogen or C _{1- 7} alkoxy; Wherein L ₂ and L ₃ are each independently a direct bond or C _{1- 7} alkylene; wherein A is an integer selected from 0 to 10; The B may be an integer selected from 0 to 4.

In the silicon nitride etching composition in accordance with one embodiment of the invention, the compound represented by the above formula (II) wherein R ₁₁ is hydroxy, halogen, amino C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7} alkoxy; In each of said R ₁₂ to R ₁₄ are independently hydroxy, halogen, C _{1- 7} alkyl, amino-C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7-alkoxy,} wherein at least one of R ₁₂ to R ₁₄ one or more hydroxy, halogen or C _{1- 7} alkoxy; Wherein L ₂ and L ₃ are each independently a direct bond or C _{1- 7} alkylene; wherein A is an integer selected from 0 to 5; The B may be an integer selected from 0 to 4.

In the silicon nitride etching composition in accordance with one embodiment of the present invention, compounds represented by the formula (3) wherein R ₂₁ to R ₂₆ are each independently selected from hydroxy, halogen, amino C _{1 - 7} alkyl, _2- C ₇ Al alkenyl, C _{1- 7} alkyl or C _{1- 7} alkoxycarbonyl, wherein R ₂₁ to at least one of R ₂₆ is hydroxy, halogen or C _{1- 7} alkoxy; Wherein L ₁ is C _{1- 7} alkylene, - (NH) -, C 1- 3 alkylene (NH) C _{1 - 3} alkylene or C ₃ alkylene _1- (NH) C _{1 - 3} alkylene group (NH ) C _{1 - 3} it may be an alkylene group.

A silicon nitride layer etching composition according to an embodiment of the present invention, based on the total weight of the silicon nitride layer etching composition, a first inorganic acid comprising 0.005 to 30% by weight of metaphosphoric acid and 60 to 95% by weight of phosphoric acid; It may include 0.005 to 10% by weight of the silicon-based compound and the remaining amount of water.

In the silicon nitride layer etching composition according to an embodiment of the present invention, the first inorganic acid may be a mixture of 5 to 20 parts by weight of the phosphoric acid based on 1 part by weight of the metaphosphoric acid.

The silicon nitride layer etching composition according to an embodiment of the present invention may further include one or more compounds selected from a fluorine-based compound, an ammonium-based compound, and the like.

In the silicon nitride layer etching composition according to an embodiment of the present invention, when the silicon-based compound is 0.005 wt% or more based on the total weight of the silicon nitride layer etching composition, the silicon nitride layer/oxide layer etching selectivity (E _SiNx /E _SiO2 ) is 1000 or more can

In the silicon nitride layer etching composition according to an embodiment of the present invention, the rate of decrease in the etching rate of the silicon nitride layer after the repeated etching process may satisfy the following relational expression (1).

[Relational Expression 1]

△ERD _SiNx ≤ 1%

[In the above relation 1,

ΔERD _SiNx is the etch rate decrease rate compared to the initial etch rate for the silicon nitride layer.

In addition, the present invention provides a method of selectively etching a silicon nitride layer compared to a silicon oxide layer using the above-described silicon nitride layer etching composition.

The present invention also provides a method of manufacturing a semiconductor device including an etching process performed using the above-described silicon nitride etching composition.

The silicon nitride layer etching composition according to the present invention can selectively etch a silicon nitride layer compared to a silicon oxide layer, and the etching selectivity is remarkably excellent.

In addition, the silicon nitride layer etching composition according to the present invention has the effect of having a small change in the etching rate and the etching selectivity for the silicon nitride layer even though the etching treatment time is increased or repeatedly used, ultimately manufacturing a semiconductor for selectively etching the silicon nitride layer Productivity in the process can be improved.

In addition, the silicon nitride layer etching composition according to the present invention has excellent storage stability, and can maintain a constant etching rate and etching selectivity for the silicon nitride layer despite long-term use or storage.

In addition, when the silicon nitride film etching composition according to the present invention is used in the etching process and the semiconductor manufacturing process, it is possible to effectively prevent damage to the film quality of the silicon oxide film or deterioration of electrical properties due to the etching of the silicon oxide film, prevent particle generation, and improve device characteristics. can

Hereinafter, the silicon nitride layer etching composition according to the present invention will be described in detail, but unless otherwise defined in technical terms and scientific terms used at this time, those of ordinary skill in the art to which this invention pertains have the meaning commonly understood and , Description of known functions and configurations that may unnecessarily obscure the gist of the present invention in the following description will be omitted.

Also, the singular form used herein may be intended to include the plural form as well, unless the context specifically dictates otherwise.

In addition, in the present specification, the unit used without special mention is based on the weight, for example, the unit of % or ratio means weight % or weight ratio.

In addition, the numerical range used herein includes the lower and upper limits and all values within the range, increments logically derived from the form and width of the defined range, all values defined therein, and the upper limit of the numerical range defined in different forms, and All possible combinations of lower bounds are included. As an example, when the numerical value is 100 to 10,000, and specifically limited to 500 to 5,000, the numerical range of 500 to 10,000 or 100 to 5,000 should also be interpreted as described in the specification of the present invention. Unless otherwise defined in the specification of the present invention, values outside the numerical range that may occur due to experimental errors or rounding of values are also included in the defined numerical range.

As used herein, the term 'comprising' is an open-ended description having an equivalent meaning to expressions such as 'comprising', 'containing', 'having' or 'characterized', and elements not listed further; Materials or processes are not excluded.

As used herein, the term 'substantially' means that other elements, materials or processes not listed together with the specified element, material or process have an unacceptably significant effect on at least one basic and novel technical idea of the invention. It means that it can be present in an amount that does not

As used herein, the term 'silicon-based compound' includes at least one silicon atom.

As used herein, the term 'etch selectivity (E _SiNx /E _SiO2 )' refers to the ratio of the etch rate of the silicon oxide layer (E _SiO2 ) to the etch rate of the silicon nitride layer (E _{SiNx ).} In addition, when the etch rate of the silicon oxide film approaches zero or the etch selectivity is large, it means that the silicon nitride film can be selectively etched.

As used herein, the term 'change in etch selectivity' refers to the absolute value of the difference in etch selectivity compared to the initial etch selectivity when the etch process is repeatedly performed two or more times using the same silicon nitride etch composition.

As used herein, the term 'Etch rate drift (ΔERD)' refers to the rate of change of the etch rate compared to the initial etch rate when the etch process is repeatedly performed two or more times using the same silicon nitride etch composition. In general, as the etching process is repeatedly performed, the etchability, that is, the etching rate, tends to decrease, so it is defined as a decrease rate, and the rate of change is also interpreted in the same meaning. Specifically, the reduction rate of the etch rate may be derived from Equation 1 below.

[Equation 1]

△ERD(%) = [1 - {(etch rate when the etching process is repeated n times or more) / (initial etching rate)}]Х100

As used herein, the singular form may also be intended to include the plural form unless the context specifically dictates otherwise.

In this specification, the units used without special mention are based on weight, for example, the unit of % or ratio means weight % or weight ratio, and weight % means any one component of the entire composition in the composition unless otherwise defined. % by weight in

As used herein, the terms 'alkyl' and 'alkoxy' are monovalent substituents and include both straight-chain or branched-chain forms.

As used herein, the term 'alkylene' refers to a divalent substituent in which one hydrogen is removed from the aforementioned alkyl.

The term in the present description, "amino-alkyl" is * - (alkylene) -NR'R "means, and wherein R 'and R" may be each independently hydrogen or C _{1- 20} alkyl.

The term in the present description, "sulfonate" is - a -S (= O) ₂ means a -OR ^a, and wherein R ^a is hydrogen, C _{1- 20} alkyl, ammonium or alkali metal (e.g., Na, K, etc.) it could be

Terms of the present specification, the "sulfate" is * -OS (= O) refers to ^a -OR _2, and wherein R ^a may be a hydrogen, C _{1- 20} alkyl, ammonium or alkali metal (e.g., Na, K, etc.) can

Terms in this specification, "phosphate" is * -OP (= O) (OR b) means a -OR ^a, and wherein R ^a is hydrogen, C _{1- 20} alkyl, ammonium or alkali metal (e.g., Na, K, etc. ), and wherein R ^b may be hydrogen or C _{1- 20} alkyl.

As used herein, the term 'halogen' refers to a halogen atom such as fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

A silicon nitride film and a silicon oxide film are representative insulating films used in a semiconductor manufacturing process. In a semiconductor process, a silicon nitride layer is a structure in contact with a silicon oxide layer, a polysilicon layer, and a silicon wafer surface, and is mainly deposited through a chemical vapor deposition (CVD) process, which is removed through etching.

Conventional wet etching has a problem in that the etch selectivity of the silicon nitride film to the silicon oxide film decreases and the etch selectivity changes when the etchant is used several times. In addition, there is a problem in that particles are generated during etching and the thickness of the silicon oxide film increases.

Accordingly, the present inventors repeated research on a composition for wet etching to solve the above-described problems. As a result, by combining a silicon-based compound with an inorganic acid in which phosphoric acid and metaphosphoric acid are mixed, it is possible to realize an extremely improved etching selectivity and to provide a silicon nitride etching composition that can effectively prevent particle generation. The present invention is proposed.

According to the present invention, it is possible to implement a significantly improved etching selectivity of the silicon nitride film compared to the conventional wet etching composition using phosphoric acid as the main etchant. In addition, according to the present invention, the etch rate and the etch selectivity for the silicon nitride layer can be maintained for a long time despite the increase in the treatment time and the number of treatments due to high stability. Therefore, the silicon nitride film etching composition according to the present invention is used in various semiconductor processes that require selective removal of the silicon nitride film, and effectively prevents the generation of particles or lowering of the etch rate that cause defects during the process, and is selective for the silicon nitride film. Allows for uniform etching.

Hereinafter, the silicon nitride layer etching composition according to the present invention will be described in detail.

The silicon nitride layer etching composition according to an embodiment of the present invention uses an inorganic acid mixed with metaphosphoric acid and phosphoric acid as a main etchant, and includes a silicon-based compound at the same time.

The silicon-based compound includes one or more silicon atoms, and may be used without limitation as long as it is used in the technical field of the etching composition, but for the implementation of a dramatically improved etching selectivity for the desired silicon nitride layer, it is represented by Formula 1 below. It is preferable to include at least one silicon-based compound selected from the indicated compounds.

Specifically, the silicon nitride layer etching composition according to an embodiment of the present invention includes a first inorganic acid including metaphosphoric acid and phosphoric acid; a silicon-based compound selected from compounds represented by the following formula (1); and the remaining amount of water.

[Formula 1]

[In Formula 1,

R ₁ to R ₄ are each independently hydrogen, hydroxy, halogen, C _{1- 20} alkyl, amino C _{1 - 20} alkyl, C _{2- 20} alkenyl, or C _{1- 20} alkoxy, a sulfonate, sulfate or phosphate, a monovalent substituent comprising the R ₁ to R ₄ is at least one of hydroxy, halogen or C _{1- 20} alkoxy;

L ₁ is an alkylene C _{1- 20} alkyl, -CH ₂ in the alkylene - is optionally replaced by -O-, -S- or -NR'-, wherein R 'is hydrogen or C _{1- 20} alkyl ;

A is an integer selected from 0 to 10;

B is an integer selected from 0 to 4.]

In the formula 1, wherein R ₁ to R ₄ are each independently hydrogen, hydroxy, halogen, C _{1- 20} alkyl, amino C _{1 - 20} alkyl, C _{2- 20} alkenyl, or C _{1- 20} alkoxy, sulfo It may be a monovalent substituent including phosphate, sulfate, or phosphate, and _{at least one of R 1} to R ₄ may be a monovalent substituent including sulfonate, sulfate or phosphate.

For example, the monovalent substituent including the sulfonate may be a monovalent substituent represented by the following formula (A).

[Formula A]

*-L _a -S(=O) ₂ -OR ^a

[In the formula A,

R ^a is hydrogen, C _{1- 7} alkyl or alkali metal;

L _a is a bond or C _{1- 7} alkylene group.]

For example, the monovalent substituent including the sulfate may be a monovalent substituent represented by the following formula (B).

[Formula B]

*-L _a -OS(=O) ₂ -OR ^a

[In the formula B,

R ^a is hydrogen, C _{1- 7} alkyl or alkali metal;

L _a is a bond or C _{1- 7} alkylene group.]

For example, the monovalent substituent including the phosphate may be a monovalent substituent represented by the following formula (C).

[Formula C]

*-L _a -OP(=O)(OR ^b )-OR ^a

[In the formula C,

R ^a is hydrogen, C _{1- 7} alkyl or alkali metal;

R ^b is hydrogen or C _{1- 7} alkyl;

L _a is a bond or C _{1- 7} alkylene group.]

In the formula 1, wherein R ₁ to R ₄ are each independently hydrogen, hydroxy, halogen, C _{1- 20} alkyl, amino C _{1 - 20} alkyl, C _{2- 20} alkenyl, or C _{1- 20} alkoxy, sulfo carbonate, a substituted monovalent containing sulfate or phosphate, in the case where the R ₁ to R ₄ is at least one or more of hydroxy, halogen or C _{1- 20} alkoxy may be in terms of minimizing the generation of particles.

Specifically, the silicon-based compound may be at least one selected from compounds represented by the following Chemical Formulas 2 and 3.

[Formula 2]

[Formula 3]

[In Formula 2 and Formula 3,

R ₁₁ to R ₁₄ and R ₂₁ to R ₂₆ are each independently hydrogen, hydroxy, halogen, C _{1- 7} alkyl, amino-C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _1-7 alkoxy, sulfo carbonate, a sulfate or a monovalent substituent comprising a phosphate, wherein R ₁₁ to R ₁₄ or R ₂₁ to R ₂₆ is at least one of hydroxy, halogen or C _{1- 7} alkoxy;

L ₁ is an alkylene C _{1- 12} alkyl, -CH ₂ in the alkylene - it is optionally replaced by -NR'-, wherein R 'is hydrogen or C _{1- 7} alkyl;

L ₂ and L ₃ are each independently a direct bond or C _{1- 7} alkylene;

A is an integer selected from 0 to 10;

B is an integer selected from 0 to 4.]

In the formula 2, wherein R ₁₁ is hydroxy, halogen, amino C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7} alkoxy; In each of said R ₁₂ to R ₁₄ are independently hydroxy, halogen, C _{1- 7} alkyl, amino-C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7-alkoxy,} wherein at least one of R ₁₂ to R ₁₄ one or more hydroxy, halogen or C _{1- 7} alkoxy; Wherein L ₂ and L ₃ are each independently a direct bond or C _{1- 7} alkylene; wherein A is an integer selected from 0 to 10; The B may be an integer selected from 0 to 4.

In the formula 2, wherein R ₁₁ is hydroxy, halogen, amino C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7} alkoxy; In each of said R ₁₂ to R ₁₄ are independently hydroxy, halogen, C _{1- 7} alkyl, amino-C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7-alkoxy,} wherein at least one of R ₁₂ to R ₁₄ one or more hydroxy, halogen or C _{1- 7} alkoxy; Wherein L ₂ and L ₃ are each independently a direct bond or C _{1- 7} alkylene; wherein A is an integer selected from 0 to 5; The B may be an integer selected from 0 to 4.

In the formula 2, wherein R ₁₁ is amino-C _{1 - 3} alkyl or C _{2- 3} alkenyl; Wherein R ₁₂ to R ₁₄ are each independently selected from hydroxy, halogen, C _{1- 3} alkyl, amino-C _{1 - 3} alkyl, C _{2- 3} alkenyl or C _{1- 3} alkoxy, wherein at least one of R ₁₂ to R ₁₄ at least one is hydroxy, halogen or C _1-3 alkoxy; Wherein L ₂ and L ₃ are each independently a direct bond or C _{1- 3} alkylene; A is an integer selected from 1 to 5; The B may be an integer selected from 1-4.

In the formula 2, wherein R ₁₁ is C _{2- 3} alkenyl; Wherein R ₁₂ to R ₁₄ are each independently selected from hydroxy, halogen, C _{1- 3} alkyl, amino-C _{1 - 3} alkyl, C _{2- 3} alkenyl or C _{1- 3} alkoxy, wherein at least one of R ₁₂ to R ₁₄ one or more hydroxy, halogen or C _{1- 3} alkoxy; Wherein L ₂ and L ₃ are each independently a direct bond or C _{1- 3} alkylene; A is an integer selected from 1 to 5; B may be an integer selected from 1 to 3.

In Formula 3, wherein R ₂₁ to R ₂₆ are each independently selected from hydroxy, halogen, amino C _1-7 alkyl, C _{2- 7} alkenyl, C _{1- 7} alkyl or C _{1- 7} alkoxycarbonyl, wherein R ₂₁ to at least one of R ₂₆ is hydroxy, halogen or C _{1- 7} alkoxy; Wherein L ₁ is C _{1- 7} alkylene, - (NH) -, C 1- 3 alkylene (NH) C _{1 - 3} alkylene or C ₃ alkylene _1- (NH) C _{1 - 3} alkylene group (NH ) C _{1 - 3} it may be an alkylene group.

In Formula 3, wherein R ₂₁ to R ₂₆ are each independently selected from hydroxy, halogen, amino C _1-3 alkyl, C _{2- 3} alkenyl, C _{1- 3} alkyl or C _{1- 3} alkoxy, wherein R ₂₁ to at least one of R ₂₆ is hydroxy, halogen or C _{1- 3} alkoxy; Wherein L ₁ may be a _1- C ₃ alkylene group. In this case, the halogen is preferably selected from fluorine and chlorine.

In Formula 3, wherein R ₂₁ to R ₂₆ are each independently selected from hydroxy, halogen, amino C _1-3 alkyl, C _{2- 3} alkenyl, C _{1- 3} alkyl or C _{1- 3} alkoxy, wherein R ₂₁ to at least one of R ₂₆ is hydroxy, halogen or C _{1- 3} alkoxy; Wherein L ₁ is _{- (NH) -, C 1-} 3 alkylene (NH) C _{1 -3} alkylene or C ₃ alkylene _1- (NH) C _{1 - 3} alkylene (NH) C _{1 - 3} alkylene may be

The silicon nitride layer etching composition of the present invention including the silicon-based compound as described above is adsorbed on the surface of the silicon oxide layer to protect the surface of the silicon oxide layer, and selectively etch the silicon nitride layer. Accordingly, it is possible to effectively prevent damage to the film quality of the silicon oxide film or deterioration in electrical properties due to the etching of the silicon oxide film, and provide a more improved etch selectivity for the silicon nitride film.

In the silicon nitride etching composition according to an embodiment of the present invention, the metaphosphoric acid may be selected from acyclic metaphosphoric acid (HPO ₃ ) and cyclic metaphosphoric acid.

When the silicon nitride layer etching composition includes cyclic metaphosphoric acid, it is more stable and is good in terms of enabling selective and uniform etching of the silicon nitride layer.

For example, the cyclic metaphosphoric acid may be selected from trimetaphosphoric acid, tetrametaphosphoric acid, hexametaphosphoric acid, and the like. In this case, in order to realize a high etch selectivity for the silicon nitride layer, specifically trimetaphosphoric acid, tetrametaphosphoric acid, or a mixture thereof may be used, and more specifically, tetrametaphosphoric acid or a mixture of trimetaphosphoric acid and tetrametaphosphoric acid it's good to be

A silicon nitride layer etching composition according to an embodiment of the present invention, based on the total weight of the silicon nitride layer etching composition, a first inorganic acid comprising 0.005 to 30% by weight of metaphosphoric acid and 60 to 95% by weight of phosphoric acid; It may include 0.005 to 10% by weight of the silicon-based compound and the remaining amount of water.

For example, the silicon nitride etching composition may include: a first inorganic acid comprising 0.01 to 20 wt% of metaphosphoric acid and 60 to 90 wt% of phosphoric acid; It may include 0.01 to 5% by weight of the silicon-based compound and the remaining amount of water.

For example, the silicon nitride etching composition may include: a first inorganic acid comprising 1 to 15 wt% of metaphosphoric acid and 75 to 90 wt% of phosphoric acid; It may include 0.05 to 3% by weight of the silicon-based compound and the remaining amount of water.

For example, the silicon nitride etching composition may include: a first inorganic acid comprising 3 to 12 wt% of metaphosphoric acid and 80 to 90 wt% of phosphoric acid; It may include 0.1 to 2% by weight of the silicon-based compound and the remaining amount of water.

When the silicon nitride layer etching composition satisfying the above-mentioned range is used in the etching process, the silicon nitride layer can be etched with high etch selectivity, and the excellent etching rate and high etch selectivity for the silicon nitride layer can be maintained even after repeated etching processes, and the etching process Since there is no disadvantage, it may be preferable to enable uniform etching.

In addition, the silicon nitride layer etching composition according to an embodiment of the present invention may further include one or two or more compounds selected from a fluorine-based compound and an ammonium-based compound. When the fluorine-based compound is added, the speed of the silicon nitride layer may be increased, and changes in the etch rate and the etch selectivity for the silicon nitride layer may be small even after repeated use. In addition, when the ammonium-based compound is added, the decrease in the etch rate and the change in the selectivity ratio are small even when used for a long period of time, and the etch rate can be kept constant.

The fluorine-based compound may be any one or a mixture of two or more selected from hydrogen fluoride, ammonium fluoride, ammonium bifluoride, and tetrafluoroboric acid.

For example, the fluorine-based compound may be included in an amount of 0.001 to 2% by weight, specifically 0.005 to 1% by weight, and more specifically, 0.01 to 0.1% by weight based on the total weight of the silicon nitride layer etching composition.

The ammonium-based compound may be any one or a mixture of two or more selected from the group consisting of aqueous ammonia, ammonium chloride, ammonium acetic acid, ammonium phosphate, ammonium peroxydisulfate, ammonium sulfate and ammonium hydrofluoric acid salt.

For example, the ammonium-based compound may be included in an amount of 0.05 to 1% by weight, specifically 0.1 to 1% by weight, and more specifically, 0.3 to 0.8% by weight based on the total weight of the silicon nitride layer etching composition. .

In addition, the silicon nitride layer etching composition according to an embodiment of the present invention may further include a second inorganic acid selected from sulfuric acid, nitric acid, hydrochloric acid, boric acid, perchloric acid, and the like. When the second inorganic acid is added, it may help to suppress particles generated during the etching process or to stabilize etching by-products.

For example, the second inorganic acid may be included in an amount of 0.01 to 10 wt% based on the total weight of the silicon nitride layer etching composition.

As described above, the silicon nitride layer etching composition according to an embodiment of the present invention can provide a high etch selectivity with respect to the silicon nitride layer as well as stably provide such an effect. In addition, it is good that the generation of particles can be effectively prevented.

Specifically, the silicon nitride layer etching composition according to an embodiment of the present invention, based on the total weight of the silicon nitride layer etching composition, when the silicon-based compound is 0.005% by weight or more, the silicon nitride layer / oxide layer etching selectivity (E _SiNx /E _SiO2 ) may be greater than or equal to 1000.

More specifically, when the silicon-based compound is 0.3 wt% or more based on the total weight of the silicon nitride layer etching composition, the silicon nitride layer/oxide layer etching selectivity (E _SiNx /E _SiO2 ) may be 2500 or more.

Most specifically, in the case of 0.5 to 2 wt%, the silicon nitride layer/oxide layer etch selectivity (E _SiNx /E _SiO2 ) may be 3500 or more.

In addition, the silicon nitride layer etching composition according to an embodiment of the present invention can realize extremely improved etch selectivity even with a smaller amount than when tetrametaphosphoric acid is included.

For example, the silicon nitride etch composition may have an etch rate of 20 to 300 Å/min for a silicon nitride layer, and an etch rate of 0 to 0.1 Å/min for a silicon oxide layer while satisfying the etch selectivity. Specifically, the silicon nitride etching composition may have an etching rate for the silicon nitride layer of 50 to 200 Å/min, and an etching rate for the silicon oxide layer from 0 to 0.05 Å/min. More specifically, the silicon nitride etching composition may have an etching rate for the silicon nitride layer of 80 to 150 Å/min and an etching rate for the silicon oxide layer of 0.001 to 0.04 Å/min.

In addition, in the silicon nitride layer etching composition according to an embodiment of the present invention, the rate of decrease in the etch rate of the silicon nitride layer after the repeated etching process may satisfy the following relational expression (1).

[Relational Expression 1]

△ERD _SiNx ≤ 1%

[In Relation 1, ΔERD _SiNx is the rate of decrease in the etch rate compared to the initial etch rate for the silicon nitride layer.]

Specifically, in the silicon nitride etching composition, the etching rate reduction rate of the silicon nitride layer may be 0.95% or less.

More specifically, in the silicon nitride etching composition, the reduction rate of the etching rate of the silicon nitride layer may be 0.80% or less.

Most specifically, in the silicon nitride layer etching composition, the rate of decrease in the etching rate of the silicon nitride layer may be 0.01 to 0.65% or less.

As described above, the silicon nitride etching composition has excellent stability and provides a stable effect even at high temperatures in a semiconductor process. In addition, even when the silicon nitride layer etching composition is used several times, the rate of change of the etching rate for the silicon nitride layer is low, so that process efficiency can be increased.

The water included in the silicon nitride etching composition according to an embodiment of the present invention is not particularly limited, but specifically may be deionized water, and more specifically, deionized water for a semiconductor process, with a specific resistance value of 18 MΩ cm It may be more than

The silicon nitride layer etching composition according to an embodiment of the present invention has a remarkable etching rate for the silicon nitride layer and excellent etching selectivity for the silicon nitride layer compared to the silicon oxide layer. In addition, it is good not to substantially induce the generation of particles.

Hereinafter, a method using the silicon nitride layer etching composition according to the present invention will be described in detail.

An aspect of the method according to an embodiment of the present invention may be a method of selectively etching a silicon nitride layer compared to a silicon oxide layer.

Another embodiment may be a method of manufacturing a semiconductor device including an etching process of selectively etching a silicon nitride layer.

The silicon nitride layer may be various silicon nitride layers, such as a SiN layer, an SiON layer, and a doped SiN layer. As a concept including such a silicon nitride film, as a specific example, it may mean a film quality mainly used as an insulating film when forming a gate electrode. However, if it is a technical field having the purpose of selectively etching a silicon nitride layer compared to a silicon oxide layer, it may be used without limitation.

In addition, the silicon oxide film is not limited as long as it is a silicon oxide film commonly used in the art, and for example, a Spin On Dielectric (SOD) film, a High Density Plasma (HDP) film, a thermal oxide film, or a borophosphate silicate (BPSG) film. Glass) film, PSG (Phospho Silicate Glass) film, BSG (Boro Silicate Glass) film, PSZ (Polysilazane) film, FSG (Fluorinated Silicate Glass) film, LP-TEOS (Low Pressure Tetra Ethyl Ortho Silicate) film, PETEOS (Plasma) film Enhanced Tetra Ethyl Ortho Silicate) Film, HTO (High Temperature Oxide) Film, MTO (Medium Temperature Oxide) Film, USG (Undoped Silicate Glass) Film, SOG (Spin On Glass) Film, APL (Advanced Planarization Layer) film, ALD (Advanced Planarization Layer) film It may be at least one layer selected from the group consisting of an atomic layer deposition (Atomic Layer Deposition) layer, a plasma enhanced oxide (PE) layer, and O ₃ -TEOS (O _{3 -Tetra Ethyl Ortho Silicate).} However, this is only a specific example, and is not limited thereto.

The etching method using the silicon nitride etching composition according to an embodiment of the present invention and the method for manufacturing a semiconductor device including the same include selectively etching only the silicon nitride layer with respect to the silicon oxide layer when the above-mentioned silicon nitride layer and the silicon oxide layer are mixed. This can be done, the etching rate is fast, and particles are not generated after etching, so it is possible to minimize the defect problem in manufacturing the semiconductor device.

In addition, the silicon nitride layer etching composition according to the present invention has high temperature stability, thereby effectively suppressing the problem that phosphoric acid heated to a high temperature etches the silicon oxide layer. Accordingly, no particles are generated due to the etching of the silicon oxide layer, thereby preventing substrate defects, and by selectively etching the silicon nitride layer, excellent semiconductor device characteristics can be realized.

A method of selectively etching a silicon nitride layer compared to a silicon oxide layer using the above-described silicon nitride layer etching composition may be performed according to a processing method commonly used in the art. As a non-limiting example, it may be performed according to a method of immersing the substrate in an etching composition solution or a spray method.

As an example, the method may be performed at a process temperature of 100 °C or higher, specifically 100 to 500 °C, more specifically, 100 to 300 °C process temperature.

The method may be advantageous in selectively and rapidly etching only the silicon nitride film with respect to the silicon oxide film when the silicon oxide film, the silicon nitride film, and the photoresist film formed on the substrate are mixed, and the generation of particles is suppressed.

Various materials may be used for the substrate, for example, silicon, quartz, glass, silicon wafer, polymer, metal, and metal oxide may be used, but is not limited thereto. As an example of the polymer substrate, a film substrate such as polyethylene terephthalate, polycarbonate, polyimide, polyethylene naphthalate, cycloolefin polymer, etc. may be used. , but not limited thereto.

The silicon oxide film, silicon nitride film, and photoresist film may each be formed as a single film, a double film, or a multi-layer (multi-layer film), and in the case of a double film or a multi-layer, the stacking order is not limited.

A method of manufacturing a semiconductor device including an etching process of selectively etching a silicon nitride layer using the above-described silicon nitride layer etching composition may also be performed according to a method commonly used in the art.

According to the manufacturing method of the semiconductor device, in a semiconductor device in which a silicon nitride layer and a silicon oxide layer are alternately stacked or mixed, selective etching of the silicon nitride layer is possible, and by effectively suppressing damage to the silicon oxide layer, the silicon oxide layer by etching It is possible to minimize the damage of the semiconductor device, greatly improving the stability, efficiency and reliability of the semiconductor device manufacturing process. In this case, the type of the semiconductor device is not particularly limited in the present invention.

Therefore, the etching method according to the present invention can selectively remove the silicon nitride film compared to the silicon oxide film, and can keep the etching rate and the etching selectivity constant despite the increase in the processing time, so that it is necessary to selectively etch the silicon nitride film. can be applied efficiently. In particular, the etching method according to the present invention has an excellent effect in suppressing the generation of particles and effectively protecting the silicon oxide film, thereby securing the stability and reliability of the process.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. However, the following Examples and Comparative Examples are merely examples for explaining the present invention in more detail, and the present invention is not limited by the following Examples and Comparative Examples. In the present invention, unless otherwise stated, all temperature means a unit of °C, and unless otherwise stated, the amount of the composition used means a unit of weight %.

(Assessment Methods)

1) Etching rate measurement

Specifically, a silicon nitride film (SiN film) wafer and a silicon oxide film wafer were prepared by depositing in the same manner as in the semiconductor manufacturing process by chemical vapor deposition (CVD).

The thickness of the composition before etching was measured using an ellipsometer (Ellipsometer, J.A WOOLLAM, M-2000U), which is a thin film thickness measuring device. The etching process was performed by immersing the wafer in each of the compositions of Examples and Comparative Examples below for 30 minutes each maintained at an etching temperature of 160° C. in a quartz bath. After the etching was completed, the etching rate was measured by washing with ultrapure water and then completely drying the remaining etchant and moisture using a drying device.

The etching rate was calculated by dividing the difference between the thickness before etching and the thickness after etching by the etching time (minutes) using an ellipsometer (Ellipsometer, J.A WOOLLAM, M-2000U).

2) Measuring etch rate reduction rate

The etching rate of the nitride film of the composition was measured by the above etch rate measurement method.

Using this etching process as one batch, 10 batches were performed in a method of repeatedly using the silicon nitride layer etching composition without exchange of the etching composition, and the etch rate reduction rate (ΔERD _SiNx ) was measured and described in Table 3 below.

The etch rate reduction rate (ΔERD _SiNx (%)) was calculated by Equation 1 below. In this case, the following initial etch rate is an etch rate during one etching process.

[Equation 1]

△ERD(%) = [1 - {(etch rate when the etching process is repeated n times or more) / (initial etching rate)}]Х100

3) Measure whether or not particles are generated

The surface of the silicon oxide film etched using the compositions of Examples and Comparative Examples was measured with a scanning electron microscope (SEM) to examine whether or not particles were generated, and the results are shown in Tables 2 and 3 below.

(Examples 1 to 11 and Comparative Examples 1 to 6)

After mixing at the composition ratio shown in Table 1 below, a silicon nitride etching composition was prepared by stirring at a speed of 500 rpm at room temperature (23° C.) for 5 minutes. The content of water was set as the remaining amount such that the total weight of the composition was 100% by weight.

As shown in Tables 2 and 3, in each case of the silicon nitride etching composition according to the present invention, the etching selectivity was 2500 or more, which was excellent. In addition, it was confirmed that the reduction rate of the etching rate for the silicon nitride layer was remarkably low despite the repeated etching process to reuse the silicon nitride layer etching composition several times. In particular, in all cases of the silicon nitride etching composition according to the present invention, particles were not generated even when the etching process was repeatedly performed.

On the other hand, in Comparative Examples 1 and 2, which is an embodiment using only inorganic acids, the etch selectivity was very low, less than 100. In addition, in the case of each of the silicon nitride film etching compositions of Comparative Examples 2, 3, 5, and 6, which do not include metaphosphoric acid, the etching selectivity was low, less than 350, or particles were generated, which was not preferable. In particular, in all cases of Comparative Examples, particles were generated when the etching process was repeatedly performed, and the reduction rate of the etching rate with respect to the silicon nitride film was significantly increased, which was not preferable.

In addition, it was confirmed that the silicon nitride film etching composition according to the present invention can further improve the silicon nitride film etching rate as it further contains a fluorine-based compound, and can lower the reduction rate for the silicon nitride film etching rate even after repeated use.

In addition, it was confirmed that, when cyclic metaphosphoric acid was included in the silicon nitride layer etching composition according to the present invention, a significant synergistic effect was exhibited on the etching selectivity for the silicon nitride layer. In particular, it was confirmed that, when tetrametaphosphoric acid was used, a more improved etching selectivity could be realized even with a smaller amount of use.

That is, according to the present invention, it is possible to selectively etch the silicon nitride film with an excellent etch selectivity, and the etch rate decrease rate is low even when used several times, and thus the production efficiency can be remarkably increased by maintaining the initial etchability. In addition, it was possible to minimize the damage to the film quality of the silicon oxide film during the etching process, effectively suppress the generation of particles, and secure the stability and reliability of the process.

Accordingly, the silicon nitride etching composition according to the present invention selectively etches the silicon nitride film while preventing the deterioration of electrical properties and generation of particles due to damage to the film quality of the silicon oxide film or over-etching of the silicon oxide film, thereby improving device characteristics.

The present invention is not limited by the above-described embodiments and the accompanying drawings, and it is common in the art to which the present invention pertains that various substitutions, modifications and changes are possible within the scope of the present invention. It will be clear to those who have knowledge.

Claims (14)

a first inorganic acid comprising metaphosphoric acid and phosphoric acid;
a silicon-based compound selected from compounds represented by the following formula (1); and
The remaining amount of water includes;
A silicon nitride etching composition that does not contain an organic acid:
[Formula 1]

In Formula 1,
R ₁ to R ₄ are each independently hydrogen, hydroxy, halogen, C _1-20 alkyl, _{aminoC 1-20} alkyl, C 2-20 alkenyl or C _1-20 alkoxy, or sulfonate, sulfate or phosphate and a monovalent substituent including, wherein _{at least one of R 1} to R ₄ is hydroxy, halogen, or C _1-20 alkoxy;
L ₁ is C _1-20 alkylene, -CH ₂ - of the alkylene may be replaced with -O-, -S- or -NR'-, wherein R' is hydrogen or C _1-20 alkyl; ;
A is an integer selected from 0 to 10;
B is an integer selected from 0 to 4. According to claim 1,
The metaphosphoric acid is
Cyclic metaphosphoric acid, silicon nitride etching composition. According to claim 1,
The metaphosphoric acid is
A silicon nitride etching composition selected from trimetaphosphoric acid, tetrametaphosphoric acid and hexametaphosphoric acid. According to claim 1,
The silicon-based compound is
At least one or more selected from the compounds represented by Formula 2 and Formula 3, a silicon nitride layer etching composition:
[Formula 2]

[Formula 3]

In Formula 2 and Formula 3,
R ₁₁ to R ₁₄ and R ₂₁ to R ₂₆ are each independently hydrogen, hydroxy, halogen, C _{1- 7} alkyl, amino-C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _1-7 alkoxy, sulfo carbonate, a sulfate or a monovalent substituent comprising a phosphate, wherein R ₁₁ to R ₁₄ or R ₂₁ to R ₂₆ is at least one of hydroxy, halogen or C _{1- 7} alkoxy;
L ₁ is an alkylene C _{1- 12} alkyl, -CH ₂ in the alkylene - it is optionally replaced by -NR'-, wherein R 'is hydrogen or C _{1- 7} alkyl;
L ₂ and L ₃ are each independently a direct bond or C _{1- 7} alkylene;
A is an integer selected from 0 to 10;
B is an integer selected from 0 to 4. 5. The method of claim 4,
The compound represented by Formula 2 is,
Wherein R ₁₁ is hydroxy, halogen, amino C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7} alkoxy;
In each of said R ₁₂ to R ₁₄ are independently hydroxy, halogen, C _{1- 7} alkyl, amino-C _{1 - 7} alkyl, _2- C ₇ alkenyl, or C _{1- 7-alkoxy,} wherein at least one of R ₁₂ to R ₁₄ one or more hydroxy, halogen or C _{1- 7} alkoxy;
wherein A is an integer selected from 0 to 10;
Wherein B is an integer selected from 0 to 4, a silicon nitride layer etching composition. 6. The method of claim 5,
The compound represented by Formula 2 is,
Wherein A is an integer selected from an integer of 1 to 5, a silicon nitride layer etching composition. 5. The method of claim 4,
The compound represented by Formula 3 is,
Wherein R ₂₁ to R ₂₆ are each independently selected from hydroxy, halogen, amino C _{1 - 7} alkyl, _2- C ₇ alkenyl, C _{1- 7} alkyl, C _{1- 7} alkoxycarbonyl, and at least one of the R ₂₁ to R ₂₆ one or more hydroxy, halogen or C _{1- 7} alkoxy;
Wherein L ₁ is C _{1- 7} alkylene, - (NH) -, C 1- 3 alkylene (NH) C _{1 - 3} alkylene or C ₃ alkylene _1- (NH) C _{1 -3} alkylene (NH ) C _1-3 alkylene, silicon nitride etching composition. According to claim 1,
Based on the total weight of the silicon nitride etching composition,
a first inorganic acid comprising 0.005 to 30% by weight of metaphosphoric acid and 60 to 95% by weight of phosphoric acid; A silicon nitride etching composition comprising 0.005 to 10% by weight of the silicon-based compound and the remaining amount of water. 9. The method of claim 8,
The first inorganic acid is
Based on 1 part by weight of the metaphosphoric acid,
5 to 20 parts by weight of the phosphoric acid is mixed, the silicon nitride layer etching composition. According to claim 1,
A silicon nitride etching composition further comprising a fluorine-based compound, an ammonium-based compound, or a mixture thereof. According to claim 1,
Based on the total weight of the silicon nitride etching composition,
When the silicon-based compound is 0.005 wt% or more, the silicon nitride layer/oxide layer etch selectivity (E _SiNx /E _SiO2 ) is 1000 or more, the silicon nitride layer etching composition. 12. The method of claim 11,
The etch rate reduction rate of the silicon nitride film after the repeated etching process satisfies the following relation 1, the silicon nitride film etching composition:
[Relational Expression 1]
△ERD _SiNx ≤ 1%
In the above relation 1,
ΔERD _SiNx is the etch rate decrease rate compared to the initial etch rate for the silicon nitride layer. A method of selectively etching a silicon nitride layer compared to a silicon oxide layer using the silicon nitride layer etching composition of any one of claims 1 to 12. A method of manufacturing a semiconductor device comprising an etching process performed using the silicon nitride layer etching composition of any one of claims 1 to 12.