KR102311335B1 - Etching compositions and etching method using the same - Google Patents

Abstract

The present invention relates to an etching composition, an etching method, and a method of manufacturing a semiconductor device using the same, and more particularly, in the case of wet etching in a semiconductor manufacturing process, a high selection capable of selectively removing a nitride layer while minimizing the etching rate of an oxide layer It relates to an etching composition including the compound of the ratio and a method of manufacturing a semiconductor device including an etching process using the etching composition.

Description

Etching composition and etching method using the same

The present invention relates to an etching composition and an etching method using the same, and more particularly, an etching composition comprising a compound of high selectivity capable of selectively removing a nitride film while minimizing the etching rate of an oxide film, and a semiconductor using the etching composition It relates to a method of etching a device.

In a semiconductor manufacturing process, _{an oxide film such as a silicon oxide film (SiO 2} ) and a nitride film such as a silicon nitride film (SiN _x ) are used as representative insulating films, either singly or by alternately stacking one or more layers. The silicon nitride layer is deposited through a chemical vapor deposition (CVD) process in a structure in contact with a silicon oxide layer, a polysilicon layer, and the surface of a silicon wafer, and is removed through dry etching and wet etching. Etching is widely used.

In a wet etching process for removing the silicon nitride layer, a mixture of phosphoric acid and deionized water is generally used. The deionized water is added to prevent a decrease in an etch rate and a change in etch selectivity for the oxide film, but there is a problem in that a defect occurs in the etching removal process of the nitride film even with a slight change in the amount of deionized water supplied. In addition, phosphoric acid is a strong acid and has a corrosive property, so it is difficult to handle.

An object of the present invention is to provide an etching composition having a higher etch selectivity for a silicon nitride film than for a silicon oxide film in a semiconductor process.

An object of the present invention is to provide an etching composition having improved silicon nitride etching rate when etching a silicon wafer.

An object of the present invention is to provide an etching composition in which an etching rate is stably maintained and a selectivity is not lowered in an etching process performed at a high temperature.

An object of the present invention is to provide an etching method using the etching composition.

One embodiment of the present invention provides an etching composition including phosphoric acid and a compound represented by the following Chemical Formula 1.

[Formula 1]

In Formula 1,

R ₁ to R ₅ are each independently selected from the group consisting of hydrogen, a hydroxyl group, a C ₁ to C ₁₀ alkyl group, and a C ₃ to C ₁₀ cycloalkyl group, _{at least one of R 1} and R ₂ is a hydroxyl group, and R ₃ At _{least one of R 5} is a hydroxyl group,

L ₁ is a single bond or -[C(R ₆ )(R ₇ )] _n -,

n is 1 to 6,

R ₆ and R ₇ are each independently hydrogen or a C ₁ ~ C ₅ alkyl group.

Another embodiment of the present invention provides an etching method using the etching composition.

The present invention can suppress the etching of the silicon oxide layer and selectively etch the silicon nitride layer by providing an etching composition in which the compound represented by Formula 1 is added to phosphoric acid.

The etching composition of the present invention has excellent high-temperature stability and may prevent particle generation to improve device characteristics.

Conventionally, a technique for removing a nitride layer using an etching composition containing phosphoric acid (H ₃ PO ₄ ) and hydrofluoric acid (HF) or nitric acid (HNO ₃ ), etc. has been known, but rather the etching of the nitride layer and the oxide layer due to an increase in the etching rate of the oxide layer Problems that impede the selection ratio appear.

There is a known technique of using a silicon additive to decrease the etching rate of the oxide film and increase the etching rate of the nitride film.

In addition, when the silicone additive is boiled in high-temperature phosphoric acid, the functional groups of the additive are separated or deteriorated through a cyclization reaction.

Accordingly, there is a need to develop an etching composition having a new composition that is not denatured at a high temperature while preventing the generation of particles while selectively etching the silicon nitride layer with respect to the silicon oxide layer by overcoming the above-mentioned problems.

Hereinafter, the present invention will be described in detail.

The present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms.

The definitions listed below are definitions of various terms used to describe the present invention. These definitions are used only to describe specific embodiments, and are not intended to limit the invention unless otherwise limited.

The term "alkyl" in the present invention is a monovalent substituent derived from a linear or branched saturated hydrocarbon having 1 to 10 carbon atoms, unless otherwise specified, and the straight or branched alkyl group has 10 or less in its main chain (e.g., C ₁ -C ₁₀ straight chain, C ₃ -C ₁₀ branched chain), preferably 4 or less, more preferably 3 or less carbon atoms. Examples of alkyl include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, and the like.

The term "cycloalkyl" in the present invention means a cyclic saturated hydrocarbon derived from a monocyclic or polycyclic non-aromatic hydrocarbon having 3 to 10 carbon atoms unless otherwise specified. Examples of such cycloalkyl include, but are not limited to, cyclopropyl, cyclopentyl, cyclohexyl, bicyclo[2.1.1]hexyl, bicyclo[2.2.1]heptyl, and the like. Cycloalkyl in the present invention may have 3,4,5,6 or 7 carbon atoms in its ring structure.

The present invention provides an etching composition comprising phosphoric acid and a compound represented by Formula 1 below.

[Formula 1]

In Formula 1, R ₁ to R ₅ are each independently selected from the group consisting of hydrogen, a hydroxyl group, a C ₁ to C ₁₀ alkyl group, and a C ₃ to C ₁₀ cycloalkyl group, and at least one of _{R 1} and R ₂ a hydroxyl group, _{at least one of R 3} to R ₅ is a hydroxyl group, L ₁ is a single bond or -[C(R ₆ )(R ₇ )] _n -, n is 1 to 6, R ₆ and R ₇ are Each independently hydrogen or C ₁ ~ C ₅ Alkyl group.

According to one embodiment of the present invention, the compound represented by the formula (1) may be a compound represented by the following formula (2).

[Formula 2]

Each of n, R ₁ to R ₅ is as defined in Formula 1 above.

In one embodiment of the present invention, R ₁ to R ₅ are each independently hydrogen, a hydroxyl group or a C ₁ to C ₅ alkyl group, preferably R ₁ to R ₅ are each independently hydrogen, a hydroxyl group, a methyl group, It may be selected from the group consisting of an ethyl group, a propyl group, and an isopropyl group, and more preferably, R ₁ to R ₅ may be all hydroxyl groups.

In one embodiment of the present invention, the compound represented by Formula 1 is (3-(trihydroxysilyl)propyl)boronic acid, (1-(trimethoxysilyl)propan-2-yl)boronic acid, and their It may be selected from the group consisting of combinations.

According to one embodiment of the present invention, the etching composition in which the compound represented by Formula 1 is added to phosphoric acid can selectively remove the nitride layer while minimizing the etching rate of the oxide layer.

More specifically, according to an exemplary embodiment of the present invention, the etching rate of the silicon oxide layer of the etching composition including the compound of Formula 1 is 0.1 to 15 Å/min. At this time, the silicon nitride film/oxide film selectivity ratio of the present invention is 15 or more, so that the nitride film can be selectively removed while minimizing the etch rate of the oxide film.

In addition, the etching composition of the present invention has excellent high-temperature stability, and prevents the generation of particles to improve device characteristics. The etching composition of the present invention introduces a boron group acting as a Lewis acid in the silicon-containing compound, thereby preventing the problem of lowering the etching ratio due to component change or cyclization in phosphoric acid at high temperature, and suppresses particle generation. N, O, P, and S have a lone pair of electrons and can donate electrons to other atoms, but boron can act as a Lewis acid because one of its coordination is vacant and can receive electrons from another atom. In addition, because of the characteristic of boron as a Lewis acid, it is very difficult to change the composition in phosphoric acid at high temperature or to polymerize the silicon-hydroxy group into silicon-oxygen-silicon to lower the etch rate.

In an embodiment of the present invention, the etching composition may include the compound represented by Formula 1 in an amount of 100 to 5000 ppm, preferably 500 to 3000 ppm.

When the content of the compound represented by Formula 1 is less than 100 ppm, the selectivity may be very low due to insufficient silicone additive.

In addition, when the compound represented by Chemical Formula 1 is added in excess of 5000 ppm, many particles may be generated and the wafer may be defective.

According to one embodiment of the present invention, the composition may contain 80 to 90 wt% of phosphoric acid, and 100 to 5000 ppm of the compound represented by Formula 1. More preferably, the phosphoric acid may be included in an amount of 80 to 90% by weight, preferably 85 to 90% by weight.

When the etching composition contains less than 80% by weight of phosphoric acid, there is a risk that foreign substances are generated or the etching rate of the silicon nitride film is lowered, so that the nitride film is not easily removed. If the concentration of the etchant is too high, the etching rate may be reduced.

Therefore, in the case of including phosphoric acid and the compound represented by Formula 1 in the weight % and ppm ranges according to the present invention, the etching composition maintains an appropriate level of stability during semiconductor processing, while maintaining a high silicon oxide/nitride selectivity and improved silicon nitride etching rate. can be implemented, enabling a stable etching process.

In one embodiment of the present invention, it may be an etching composition, characterized in that the additive for improving the etching rate is further included.

The additive refers to any additive commonly used in the art to improve etching performance, such as a surfactant, a metal ion sequestering agent, and a corrosion inhibitor.

In particular, when an additive for improving the etching rate is included, 500 ppm or more of the compound represented by Formula 1 is preferably included in view of implementing a high selectivity.

In one embodiment of the present invention, a phenol-based compound may be added as an additive to the etching composition. The phenol-based compound may include phenol, benzenediol, or benzenetriol. The phenolic compound may ultimately prevent discoloration of the etching composition by suppressing polyphosphoric acid generated by the reaction of the silicon-based additive in high-temperature phosphoric acid.

According to another embodiment of the present invention, the etching composition of the present invention may be prepared as follows.

An etching composition is prepared by adding the compound represented by Formula 1 or 2 to phosphoric acid. At this time, the concentration of the compound represented by Formula 1 in the etching composition is 200 to 50000 ppm, preferably 1000 to 20000 ppm.

Mixing the etching composition at room temperature for 10 minutes to 3 hours is preferably 1 hour. After that, it is stirred at 25 to 100 ^o C, preferably 65 to 85 ^{o is} C. Thereafter, the wafer is etched for 10 seconds to 10 minutes, preferably 1 minute to 5 minutes. Finally, rinse with water for 1 second to 5 minutes, preferably for 10 seconds to 1 minute.

According to another embodiment of the present invention, a phenolic compound may be added to phosphoric acid.

A phenolic compound is added to phosphoric acid, wherein the concentration of the phenolic compound is 100 to 30000 ppm, preferably 1000 to 5000 ppm. After that, 100 to 30000 ppm is possible to put the amine-based silicone additive, but the preferred amount is 5000 to 10000 ppm.

If the amount of the phenolic compound is less than 100 ppm, it is insufficient to stop the phenomenon of polymerization in phosphoric acid, and if it exceeds 30000 ppm, it is rather difficult to dissolve in phosphoric acid.

Another embodiment of the present invention provides a method of etching a silicon thin film using the prepared etching composition.

One embodiment of the present invention provides an etching method comprising etching any one selected from the group consisting of a silicon nitride layer, a silicon oxide layer, and a combination thereof using the etching composition.

One embodiment of the present invention provides a method of manufacturing a semiconductor device including an etching process performed using the etching composition.

In the present invention, the etching process is to selectively etch a silicon nitride film with respect to a silicon oxide film, and may be a method for manufacturing a semiconductor device that is performed at a temperature of 140 to 195, and other processes may use commonly known methods. A detailed description is omitted.

Hereinafter, specific embodiments of the present invention are presented. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

Example

etching Preparation of the composition

An etching composition was prepared by adding the compound represented by Formula 1 to phosphoric acid to have an initial concentration of 2000 ppm.

The etching compositions according to Example 1 and Comparative Examples 1 and 2 are shown in [Table 1].

etching composition phosphoric acid silicic acid compound of formula 1 Kinds weight% Example 1 85% by weight -

1500ppm Example 2 85% by weight -

1500ppm Comparative Example 1 85% by weight - - - Comparative Example 2 85% by weight 1500ppm - -

[Measurement of physical properties]

The etching compositions prepared according to Examples and Comparative Examples were etched for 1 minute at 165 ^o _{C for ALD SiO X .}

The etch rate was measured a total of 5 times, and the average result value is shown in [Table 2] below.

Thickness before etching (Å) After etching thickness (Å) Etch rate (Å/min) Example 1 166.23 156.03 10.20 Example 2 167.24 162.12 5.12 Comparative Example 1 167.87 147.77 20.10 Comparative Example 2 168.19 155.79 12.4

As shown in [Table 2], the etching compositions of Examples 1 and 2 showed a lower etching ratio of the silicon oxide layer than the etching compositions of Comparative Examples 1 and 2.

[Etch rate measurement]

The etching composition prepared according to Examples and Comparative Examples was etched by putting a silicon nitride film substrate while changing the etching temperature.

The silicon nitride film was planarized before being put into the etching composition, and the planarization operation was carried out by diluting 50% by mass of hydrofluoric acid to 200:1 and then immersing it in diluted hydrofluoric acid for 30 seconds.

The etching rate was determined by etching the silicon nitride film for 300 seconds using an ellipsometer (Nano-View, SE MG-1000; Ellipsometery), and dividing the difference between the thickness before and after etching of both films by the etching time (minutes). calculated.

[Table 3] shows the results of the etching rate according to time.

division Process temperature () Nitride etch rate
(Å/min) Oxide etch rate
(Å/min) selection fee
(nitride film/oxide film) Example 1 175 2011.11 12.30 16.35 Example 2 175 200.15 8.99 22.26 Comparative Example 1 175 1999.97 31.88 6.27 Comparative Example 2 175 201.55 16.72 12.05

As shown in [Table 3], it was found that the etching compositions of Examples 1 and 2 increased the etching rate of the nitride film and suppressed the etching rate of the oxide film.

This indicates a high selectivity of the etching composition according to the present invention, and the effect of the present invention was confirmed in the silicon etching process.

[Color Measurement]

Preparation of Example 3 and Comparative Example 3

In Comparative Example 3, an etching composition was prepared by adding 3-aminopropylmethyldiethoxysilane to phosphoric acid to have an initial concentration of 5000 ppm.

In Example 3, 10000 ppm of phenol was added to the etching composition of Comparative Example 3.

The following [Table 4] shows data of color change observed in the etching compositions of Example 3 and Comparative Example 3 according to temperature and time.

Temperature (℃) time (min) color Temperature (℃) time (min) color Example 3 155 30 yellow Comparative Example 3 155 30 yellow 60 yellow 60 dark yellow 180 dark yellow 180 light brown 360 light brown 360 black Example 3 165 30 yellow Comparative Example 3 165 30 yellow 60 yellow 60 light brown 180 dark yellow 180 dark brown 360 Red 360 black Example 3 175 30 yellow Comparative Example 3 175 30 yellow 60 dark yellow 60 dark brown 180 Red 180 black 360 light brown 360 black

As shown in [Table 4], the etching composition of Example 3 showed little change in color over time at high temperature, but it was found that Comparative Example 3 had a very large change in color over time.

Claims (10)

phosphoric acid; and
An etching composition comprising a compound represented by Formula 1 below:
[Formula 1]

In Formula 1,
R ₁ to R ₅ are each independently selected from the group consisting of hydrogen, a hydroxyl group, a C ₁ to C ₁₀ alkyl group, and a C ₃ to C ₁₀ cycloalkyl group, _{at least one of R 1} and R ₂ is a hydroxyl group, and R ₃ At _{least one of R 5} is a hydroxyl group,
L ₁ is a single bond or -[C(R ₆ )(R ₇ )] _n -,
n is 1 to 6,
R ₆ and R ₇ are each independently hydrogen or a C ₁ ~ C ₅ alkyl group.
The method of claim 1,
Etching composition, wherein the compound represented by the formula (1) is a compound represented by the following formula (2):
[Formula 2]

Each of n, R ₁ to R ₅ is as defined in claim 1.
3. The method of claim 1 or 2,
R ₁ to R ₅ are each independently hydrogen, a hydroxy group, or a C ₁ to C ₅ alkyl group, the etching composition.
3. The method of claim 1 or 2,
R ₁ to R ₅ are all hydroxyl groups, the etching composition.
phosphoric acid; and
An etching composition comprising a compound selected from the group consisting of (3-(trihydroxysilyl)propyl)boronic acid, (1-(trimethoxysilyl)propan-2-yl)boronic acid, and combinations thereof.
3. The method of claim 1 or 2,
80 to 90% by weight of phosphoric acid, and
100 to 5000 ppm of the compound represented by Formula 1
comprising, an etching composition.
3. The method of claim 1 or 2,
An etching rate of the silicon oxide layer of the etching composition is 0.1 to 15 Å/min.
3. The method of claim 1 or 2,
The silicon nitride layer / oxide layer selectivity of the etching composition is 15 or more, the etching composition.
3. The method of claim 1 or 2,
An etching composition, characterized in that it further comprises an additive for improving the etching rate.
A method for etching a semiconductor device, comprising: etching any one selected from the group consisting of a silicon nitride layer, a silicon oxide layer, and a combination thereof using the etching composition according to claim 1 or 2 .