KR102668574B1 - Etchant composition - Google Patents

Abstract

The etching composition according to the present invention includes nitric acid; ammonium salt; and water, but not including phosphoric acid and phosphate salts.

Description

Etching composition {ETCHANT COMPOSITION}

The present invention relates to an etching composition, specifically, an etching composition capable of realizing a high selective etching ratio for tungsten films and nitride films.

Titanium nitride (TiN), a titanium-based metal, is used as a base layer for precious metals, aluminum (Al), and copper (Cu) wiring in semiconductor devices, liquid crystal displays, Micro Electro Mechanical Systems (MEMS) devices, and printed wiring boards. It is used as a cap layer. Additionally, in semiconductor devices, it is sometimes used as a barrier metal or gate metal.

In addition to the titanium nitride or titanium nitride-based metal, tungsten or tungsten-based metal is used in liquid crystal displays, gate electrodes of thin-film transistors in semiconductor devices, wiring, barrier layers, contact holes, and filling via holes. Additionally, in the field of microelectronic control technology, tungsten is also used as a heater.

In particular, a metal nitride film such as titanium nitride serves as a barrier layer to prevent etching of the underlying material by suppressing etching from the etchant composition. Therefore, it is difficult to etch metal nitride films such as titanium nitride with commonly known etchants, so a common method of removing them is using chemical mechanical polishing (CMP), which combines the chemical properties of the etchant and the physical effects of polishing.

However, the chemical mechanical polishing method is inefficient because the process is complicated, there are limitations in process application, there is a high possibility of other contamination, and the cost is higher than the general wet process.

Accordingly, Republic of Korea Patent Publication No. 2015-0050278 relates to an etching composition for a laminate of a titanium nitride film and a tungsten film, an etching method using the same, and a semiconductor device manufactured therefrom, comprising (a) 50 to 80% by weight of phosphoric acid, (b) Disclosed is an etching composition for a laminate of a titanium nitride film and a tungsten film, comprising 5 to 20% by weight of nitric acid, (c) 0.01 to 10% by weight of an ammonium-based compound, and (d) the balance of a solvent.

However, when phosphoric acid or a phosphate is included in even a small amount, the phosphate group contained in the phosphoric acid or phosphate increases the dissociation rate of the tungsten film, causing a problem in which some defects occur in the subsequent deposition process.

Republic of Korea Patent Publication No. 2015-0050278 (2015.05.08)

The present invention seeks to provide an etching composition that does not contain phosphoric acid or phosphate and thus has an excellent selective etching ratio for a titanium nitride film.

The present invention relates to nitric acid; ammonium salt; and water, but not phosphoric acid or phosphate salt.

The etching composition according to the present invention does not contain phosphoric acid or phosphate, so it has the advantage of improving the etching rate of a titanium nitride film compared to a tungsten film, enabling highly selective etching.

Hereinafter, the present invention will be described in more detail.

In the present invention, when a member is said to be located “on” another member, this includes not only the case where a member is in direct contact with another member, but also the case where another member is interposed between the two members.

In the present invention, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

One aspect of the invention is nitric acid; ammonium salt; and water, but does not contain phosphoric acid or phosphate.

The etching composition according to the present invention can not only implement highly selective etching of titanium nitride films and tungsten films, but _also suppress damage (damage free) to underlying materials such as _SiO There are benefits that can be implemented.

nitric acid

The etching composition according to the present invention contains nitric acid. Since nitric acid is an inorganic acid and has the properties of an oxidizing agent, it is possible to etch metal. In short, it not only increases the etch rate of the titanium nitride film, but also serves to oxidize the tungsten film. Specifically, it serves to realize the etching speed of the tungsten film as required in the process.

Since the oxidation rate increases as the temperature of the nitric acid-containing etching composition increases, the appropriate process temperature for using the nitric acid-containing etching composition is 50 to 70°C, and the appropriate treatment time is within 5 minutes.

As the nitric acid content increases, high selectivity etching of titanium nitride films and tungsten films becomes possible, but if the content is too high, nitric acid fumes may be generated to some extent at high temperatures.

In one embodiment of the present invention, nitric acid may be included in an amount of 25 to 75% by weight, specifically 40 to 70% by weight, and more specifically 56 to 70% by weight, based on 100% by weight of the total etching composition.

When the nitric acid is contained within the above range, the etching rate of the tungsten film is lowered, the etching effect of the titanium nitride film is excellent, and the etching rate is appropriate, making it easy to control the etching amount of the titanium nitride film.

ammonium salt

The etching composition according to the present invention includes an ammonium salt. The ammonium salt may serve to prevent oxidation of tungsten by nitric acid and thereby reduce the etching rate of tungsten. Accordingly, there is an advantage in that the selectivity ratio of the titanium nitride film and the tungsten film of the etching composition according to the present invention can be increased.

The ammonium salt does not contain a phosphate group, and in another embodiment of the present invention, the ammonium salt is ammonium sulfate, ammonium peroxomonosulfate, ammonium nitrate, ammonium formate, ammonium acetate, ammonium chloride, ammonium chlorate, Ammonium iodate, ammonium perborate, ammonium perchlorate, ammonium periodate, ammonium persulfate, ammonium hypochloride, tetramethylammonium chloride, tetramethylammonium chlorate, tetramethylammonium iodate, tetramethylammonium perborate, tetramethylammonium It may be one or more selected from the group consisting of perchlorate, tetramethylammonium periodate, tetramethylammonium persulfate, and tetrabutylammonium peroxomonosulfate. It is preferable that the ammonium salt is at least one selected from the above group because the above-mentioned effects are maximized.

In another embodiment of the present invention, the ammonium salt may be included in an amount of 0.01 to 1% by weight based on 100% by weight of the total etching composition.

In another embodiment of the present invention, the ammonium salt may be included in an amount of 0.1 to 1% by weight based on 100% by weight of the total etching composition.

When the ammonium salt is contained within the above range, etching of tungsten is suppressed, and the phenomenon of recrystallization of the ammonium salt during treatment with a single tool, which is a single-wafer type cleaning device, and the occurrence of particle defects can be suppressed. It is desirable.

water

The etching composition according to the present invention contains water.

The water may include pure water, ultrapure water, deionized water, distilled water, etc., and is preferably deionized water. Use deionized water with a water resistivity value of 18 MΩ·cm or more, which shows the degree to which ions have been removed from the water. It is more desirable to do so.

When the nitric acid is in an aqueous solution, the water may be partially or entirely contained in the nitric acid, but is not limited to this.

The water may be included as the remainder based on 100% by weight of the total etching composition.

The etching composition according to the present invention does not contain phosphoric acid or phosphate salts. In short, the etching composition according to the present invention does not contain phosphoric acid and/or phosphate salts.

The phosphate can be interpreted in the same way as the phosphate anion, and is not particularly limited as long as it is selected from salts in which one or two hydrogens of phosphoric acid are substituted with an alkali metal or alkaline earth metal. Ammonium phosphate monobasic, Ammonium phosphate dibasic, sodium phosphate monobasic, sodium phosphate dibasic, potassium phosphate monobasic or potassium phosphate dibasic However, it is not limited to this and can be interpreted as a term commonly interpreted in the art.

Since the etching composition according to the present invention does not contain the phosphoric acid and/or phosphate, etching of the tungsten film is suppressed and highly selective etching can be implemented by etching the titanium nitride film.

In another embodiment of the present invention, the etching composition may be a nitride film etching composition. In short, the etching composition according to the present invention can etch a nitride film.

Specifically, the etching composition according to the present invention is capable of implementing highly selective etching of titanium nitride films and tungsten films. More specifically, the etching composition according to the present invention has the advantage of suppressing etching of the tungsten film and selectively etching the titanium nitride film.

In addition, there is an advantage of suppressing damage (damage free) to underlying materials such as SiO _x , AlO _x , and Poly-Si, which are the main components of semiconductors.

Hereinafter, examples will be given in detail to explain the present specification in detail. However, the embodiments according to the present specification may be modified into various other forms, and the scope of the present specification is not to be construed as being limited to the embodiments described in detail below. The embodiments of this specification are provided to more completely explain the present specification to those with average knowledge in the art. In addition, "%" and "part" indicating content below are based on weight, unless otherwise specified.

Example and Comparative example

An etching composition was prepared according to the ingredients and composition shown in Table 1 below. The prepared composition was treated using the treatment conditions according to Table 1 below.

Processing conditions Etching composition (% by weight) Temperature (℃) Time (min) nitric acid phosphoric acid acetic acid AS APS AA AP DIW Example 1 60 10 70.0 - - 0.1 - - - 29.9 Example 2 60 10 56.0 - - 0.1 - - - 43.9 Example 3 60 10 42.0 - - 0.1 - - - 57.9 Example 4 60 10 28.0 - - 0.1 - - - 71.9 Example 5 70 10 70.0 - - 0.1 - - - 29.9 Example 6 50 10 70.0 - - 0.1 - - - 29.9 Example 7 60 10 70.0 - - 0.01 - - - 29.99 Example 8 60 10 70.0 - - 1.0 - - - 29 Example 9 60 10 70.0 - - 1.5 - - - 28.5 Example 10 60 10 70.0 - - - 0.1 - - 29.9 Example 11 60 10 70.0 - - - - 0.1 - 29.9 Comparative Example 1 60 10 5 65 10 - - - - 20 Comparative Example 2 60 10 15 65 - - 1.0 - - 19 Comparative Example 3 60 10 70.0 - - - - - 0.1 29.9 AS: Ammonium Sulfate
APS: Ammonium Persulfate
AA: Ammonium Acetate
AP: Ammonium Phosphate

Experiment example 1: Etch rate evaluation

W, TiN, _SiO Etch rate evaluation for each composition was evaluated using SEM and ellipsometer, and the results are shown in Table 2.

The degree of etching for the silicon oxide (SiO _x ) film and poly-si film was judged according to the evaluation criteria below and is shown in Table 2 below.

<Standards for evaluating the degree of etching for silicon oxide film and aluminum oxide film>

○: Etching speed 1 Å/min or less

×: Etching rate exceeds 1 Å/min

Experiment example 2: Solubility evaluation

During the etching process, whether the components of the etchant composition precipitated out and the solubility of the etchant composition were judged according to the evaluation criteria below, and are shown in Table 2 below. Turbidity (NTU) was measured using HACH's 2100AN.

<Solubility evaluation criteria>

○: Turbidity measurement result NTU (Nephelometric Turbidity Unit) is 1 or less

×: Turbidity measurement result NTU (Nephelometric Turbidity Unit) exceeds 1

division TiN
(E/R, Å/min) W
(E/R, Å/min) TiN/W
(etching fee) SiO _x Poly-si Solubility Example 1 32.1 1.2 26.8 ○ ○ ○ Example 2 26.4 1.2 22.0 ○ ○ ○ Example 3 19.7 1.4 14.1 ○ ○ ○ Example 4 11.3 3.6 3.1 ○ ○ ○ Example 5 64.4 2.8 23.0 ○ ○ ○ Example 6 8.5 0.8 10.6 ○ ○ ○ Example 7 33.1 2.2 15.0 ○ ○ ○ Example 8 29.1 1.2 24.25 ○ ○ ○ Example 9 28.5 1.1 25.9 ○ ○ × (small amount of precipitation) Example 10 31.8 1.5 21.2 ○ ○ ○ Example 11 30.7 1.3 23.6 ○ ○ ○ Comparative Example 1 3.8 6.2 0.61 ○ ○ ○ Comparative Example 2 3.9 6.1 0.64 ○ ○ ○ Comparative Example 3 4.0 3.6 1.1 ○ ○ ○

As can be seen from Table 2, in the example using the etching composition according to the present invention, the etching selectivity for the tungsten nitride film and the tungsten film is excellent.

Claims (6)

nitric acid; ammonium salt; and water,
An etching composition for etching titanium nitride films and tungsten films that does not contain phosphoric acid or phosphate,
The etching composition wherein the nitric acid is contained in an amount of 40 to 75% by weight based on 100% by weight of the total etching composition. delete According to paragraph 1,
The etching composition wherein the ammonium salt is contained in an amount of 0.01 to 1% by weight based on 100% by weight of the total etching composition. According to paragraph 3,
The etching composition wherein the ammonium salt is contained in an amount of 0.1 to 1% by weight based on 100% by weight of the total etching composition. According to paragraph 1,
The ammonium salt includes ammonium sulfate, ammonium peroxomonosulfate, ammonium nitrate, ammonium formate, ammonium acetate, ammonium chloride, ammonium chlorate, ammonium iodate, ammonium perborate, ammonium perchlorate, ammonium periodate, ammonium persulfate, Ammonium hypochloride, tetramethylammonium chloride, tetramethylammonium chlorate, tetramethylammonium iodate, tetramethylammonium perborate, tetramethylammonium perchlorate, tetramethylammonium periodate, tetramethylammonium persulfate and tetrabutylammonium peroxo. An etching composition comprising at least one selected from the group consisting of monosulfates. delete