KR20200107139A - Etchant composition - Google Patents

Abstract

An etching composition according to the present invention comprises nitric acid, an ammonium salt, and water while not containing phosphoric acid and phosphate, thereby having excellent selective etching ratio of a titanium nitride film.

Description

Etching composition {ETCHANT COMPOSITION}

The present invention relates to an etching composition, in particular, to an etching composition capable of implementing a high selective etching ratio for a tungsten layer and a nitride layer.

Titanium nitride (TiN), a titanium-based metal, is used as a precious metal for semiconductor devices, liquid crystal displays, micro-electromechanical systems (MEMS) devices, printed wiring boards, etc., as well as the underlying layer of aluminum (Al) and copper (Cu) wiring It is used as a cap layer. In addition, in a semiconductor device, it may be used as a barrier metal or a gate metal.

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

In particular, a metal nitride film such as titanium nitride serves as a barrier layer to prevent etching from the etchant composition, thereby preventing the underlying material from being etched. Therefore, it is difficult to etch a metal nitride film such as titanium nitride with a commonly known etchant 　It is generally a method of removing using a chemical mechanical polishing (CMP) method that adds the chemical properties of the etchant and the physical effect of polishing.

However, in the case of the chemical mechanical polishing method, the process is complicated, there is a limit to the application of the process, there are many sources of other contamination, and the cost is higher than that of the general wet process, so it is inefficient.

Accordingly, Korean Patent Application 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, (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 compound, and (d) a residual amount of a solvent.

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

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

An object of the present invention is to provide an etching composition that does not contain phosphoric acid and phosphate, and thus has an excellent selective etching ratio of a titanium nitride film.

The present invention is nitric acid; Ammonium salt; And water, but phosphoric acid and phosphate; it provides an etching composition that does not contain.

Since the etching composition according to the present invention does not contain phosphoric acid and phosphate, there is an advantage in that the etching rate of the titanium nitride layer is improved compared to that of the tungsten layer, thereby enabling highly selective etching.

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

In the present invention, when a member is positioned "on" another member, this includes not only the case where the member is in direct contact with the other 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, it means that other components may be further included rather than excluding other components unless otherwise specified.

One aspect of the present invention is nitric acid; Ammonium salt; And including water, phosphoric acid and phosphate; relates to an etching composition not containing.

The etching composition according to the present invention can not only implement highly selective etching of the titanium nitride film and the tungsten film, but also prevent damage to the underlying materials such as SiO _x , AlO _x , and Poly-Si, which are major components of the semiconductor. There is an advantage that can be implemented.

nitric acid

The etching composition according to the present invention includes nitric acid. Since nitric acid is an inorganic acid and has properties of an oxidizing agent, metal can be etched. In other words, it not only increases the etch rate of the titanium nitride film, but also serves to oxidize the tungsten film. Specifically, the tungsten layer serves to implement an etching rate as necessary for the process.

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

The higher the nitric acid content, the higher the selectivity etching of the titanium nitride layer and the tungsten layer becomes possible. However, if the content is too high, fume nitrate may be generated at a high temperature.

In one embodiment of the present invention, the 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 amount of the etching composition.

When the nitric acid is contained within the above range, the etching rate of the tungsten layer is lowered, the etching effect of the titanium nitride layer is excellent, and the etching rate is adequate, so that the etching amount of the titanium nitride layer can be easily adjusted.

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, thereby lowering an etching rate of tungsten. Accordingly, there is an advantage of increasing the selectivity of the titanium nitride layer and the tungsten layer of the etching composition according to the present invention.

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. When the ammonium salt is at least one selected from the group, it is preferable because the above-described effect is 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 amount of the 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 amount of the etching composition.

When the ammonium salt is included within the above range, the etching of tungsten is suppressed, and the ammonium salt is recrystallized during treatment with a single tool, which is a sheet-fed cleaning device, thereby suppressing the occurrence of particle defects. It is preferable.

water

The etching composition according to the present invention contains water.

The water may be pure water, ultrapure water, deionized water, distilled water, etc., preferably deionized water, and deionized water having a specific resistance value of 18 MΩ·cm or more showing the degree of ion removal from water is used. It is more preferable to do it.

When the nitric acid is in an aqueous solution state, the water may be in a state in which some or all of the nitric acid is included, but is not limited thereto.

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

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

The phosphate salt is not particularly limited as long as the hydrogen of phosphoric acid is selected from a salt substituted with one or two alkali metals or alkaline earth metals, which can be interpreted in the same manner as the phosphate anion, and the first ammonium phosphate monobasic, Ammonium phosphate dibasic, sodium phosphate monobasic, sodium phosphate dibasic, potassium phosphate monobasic or potassium phosphate dibasic It may be, but is not limited thereto, and may be interpreted as terms 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 layer is suppressed, and highly selective etching can be implemented by etching the titanium nitride layer.

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

Specifically, the etching composition according to the present invention can implement highly selective etching of a titanium nitride film and a tungsten film. More specifically, the etching composition according to the present invention has the advantage of suppressing etching of the tungsten layer and selectively etching the titanium nitride layer.

In addition, there is an advantage of being able to suppress (damage free) damage to lower materials such as SiO _x , AlO _x , and Poly-Si, which are major constituent films of a semiconductor.

Hereinafter, examples will be described in detail to describe the present specification in detail. However, the embodiments according to the present specification may be modified in various forms, and the scope of the present specification is not construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely describe the present specification to those of ordinary skill in the art. In addition, "%" and "parts" indicating content hereinafter are based on weight unless otherwise noted.

Example And Comparative example

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

Treatment 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

Experimental example 1: Etch rate evaluation

W, TiN, SiO _x , Poly-si monolayers were immersed in the etching compositions according to Examples and Comparative Examples. 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 the poly-si film was determined according to the following evaluation criteria, and then shown in Table 2 below.

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

○: Etching speed 1 Å/min or less

×: Etching speed exceeds 1 Å/min

Experimental example 2: solubility evaluation

During the etching process, whether constituents of the etchant composition were precipitated out, and the solubility of the etchant composition was determined according to the following evaluation criteria, and then shown in Table 2 below. Turbidity (NTU) was measured using 2100AN of HACH.

<Solubility evaluation criteria>

○: As a result of turbidity measurement, NTU (Nephelometric Turbidity Unit) is less than 1

×: As a result of turbidity measurement, NTU (Nephelometric Turbidity Unit) exceeds 1

division TiN
(E/R, Å/min) W
(E/R, Å/min) TiN/W
(Etching cost) 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 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, it can be seen that in the case of the embodiment 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 that does not contain phosphoric acid and phosphate. The method of claim 1,
The etching composition that the nitrate is contained in an amount of 40 to 75% by weight based on 100% by weight of the total amount of the etching composition. The method of claim 1,
The etching composition that the ammonium salt is contained in an amount of 0.01 to 1% by weight based on 100% by weight of the total amount of the etching composition. The method of claim 3,
The etching composition that the ammonium salt is contained in an amount of 0.1 to 1% by weight based on 100% by weight of the total amount of the etching composition. The method of claim 1,
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 perchlorate, tetramethylammonium periodate, tetramethylammonium persulfate and tetrabutylammonium peroxo Etching composition that is at least one selected from the group consisting of monosulfate. The method of claim 1,
The etching composition is a nitride film etching composition.