KR102415954B1 - ETCHANT COMPOSITION FOR ETHCING TiN LAYER AND METHOD FOR FORMING METAL LINE USING THE SAME - Google Patents

Abstract

Based on the total weight of the composition, (A) 75 to 95% by weight of at least one selected from sulfuric acid and alkylsulfonic acid, (B) 0.3 to 10% by weight of peroxide, (C) persulfates and Formula 1 A composition for etching a TiN film comprising 0.0005 to 3% by weight of at least one auxiliary oxidizing agent selected from the group consisting of N-oxide compounds, and (D) the remaining amount of water, and a method of forming a metal wiring using the composition for etching provides:
[Formula 1]

Description

An etchant composition for a titanium nitride (TiN) film and a method for forming a metal wiring using the same

The present invention relates to an etchant composition for a titanium nitride (TiN) film and a method for forming a metal wiring using the same.

A photoresist (PR) mask patterned by general photolithography has a thick thickness and a fast etching rate. Also, the use of the PR mask causes redeposition on the side of the MTJ stack by etching residues.

When a pattern of a metal layer to be etched with a slow etch rate is formed using a PR mask, the fast etch rate of the PR mask lowers the etch selectivity of the etch target metal layer with a slow etch rate, resulting in a low etch gradient. Therefore, these characteristics of the PR mask deteriorate the characteristics of the device and become a factor hindering the high integration.

Recently, in order to solve the problem of the PR mask as described above, a technique using a hard mask has been used. As the hard mask material, a TiN thin film or the like is used.

The TiN hardmask is etched using inductively coupled plasma reactive ion etching (ICPRIE) using high-density plasma.

As a wet etching method of the TiN hard mask, Korean Patent Registration No. 1282177 discloses an etchant of titanium-based metal, tungsten-based metal, titanium-tungsten-based metal or nitride thereof, characterized in that it contains perhydrate, organic acid salt, ammonia and water. is starting However, other than the above method, a wet etching method of a TiN hardmask is not well known. In particular, a wet etching method of a TiN hardmask having high selectivity with respect to a metal layer or metal wiring including tungsten has not been reported.

Therefore, development of a wet etching method for a TiN hard mask and a wet etching method for a TiN hard mask having high selectivity with respect to a metal film or metal wiring containing tungsten is required.

Korean Patent Registration No. 1282177

The present invention is to solve the above problems of the prior art, and an object of the present invention is to provide a composition for etching a TiN film capable of efficiently wet-etching a TiN film.

Another object of the present invention is to provide a composition for etching a TiN film having high selectivity with respect to a metal film or metal wiring containing tungsten.

In addition, the present invention selectively provides a TiN film without damage to high-k materials such as SiNx, SiOx, poly Si, HfOx, and ZrOx, which are the main constituent film materials of semiconductors, as well as low-k materials such as TEOS and organosilicate glasses (OSG). An object of the present invention is to provide a composition for etching an etchable TiN film.

Another object of the present invention is to provide a method for forming a metal wiring using the above-described composition for etching a TiN layer.

the present invention

with respect to the total weight of the composition,

(A) 75-95 wt% of at least one selected from sulfuric acid and alkylsulfonic acid,

(B) 0.3 to 10% by weight of peroxide;

(C) 0.0005 to 3 wt% of at least one auxiliary oxidizing agent selected from the group consisting of persulfates and N-oxide compounds represented by the following formula (1), and

(D) provides a composition for etching a TiN film comprising a residual amount of water:

[Formula 1]

In the above formula,

R1 to R3 may each independently be a C1-C4 alkyl group,

R2 and R3 may be combined with each other to form a C4~C6 heterocyclic ring with an existing nitrogen atom.

Also, the present invention

In the method of forming a metal wiring including a metal film or metal wiring containing tungsten (W) as a lower metal film or metal wiring, and using a TiN film as a hard mask,

and selectively etching the TiN hardmask with respect to the metal film or metal wiring containing tungsten (W), wherein the etching step is performed using the etchant of the present invention. provide a way

The composition for etching a TiN film of the present invention enables efficient wet etching of the TiN film.

In addition, since the composition for etching a TiN film of the present invention has high selectivity with respect to a metal film or metal wiring containing tungsten, it is possible to selectively etch the TiN film even when a metal film or metal wiring containing tungsten is formed. can

In addition, the composition for etching a TiN film of the present invention is for high-k materials such as SiNx, SiOx, poly Si, HfOx, and ZrOx, which are the main constituent film materials of semiconductors, as well as for low-k materials such as TEOS and organosilicate glasses (OSG). It is possible to selectively etch the TiN film without damage.

In addition, the composition for etching a TiN film of the present invention can be very usefully used, particularly when etching a TiN hard mask.

The present invention, based on the total weight of the composition, (A) at least one selected from sulfuric acid and alkyl sulfonic acid (alkyl sulfonic acid) 75 to 95% by weight, (B) peroxide 0.3 to 10% by weight, (C) persulfate It relates to a composition for etching a TiN film comprising 0.0005 to 3% by weight of at least one auxiliary oxidizing agent selected from the group consisting of N-oxide compounds represented by Formula 1 below, and (D) the balance of water:

[Formula 1]

In the above formula,

R1 to R3 may each independently be a C1-C4 alkyl group,

R2 and R3 may be combined with each other to form a C4~C6 heterocyclic ring with an existing nitrogen atom.

In addition to the nitrogen atom present in the group, it may further include one hetero atom selected from N, O, and S.

The TiN film refers to a film made of TiN regardless of its use. For example, the TiN layer may form a metal wiring or may be used as a TiN hard mask.

The composition for etching the TiN film may be usefully used for selective etching of the TiN film in the presence of a metal film or metal wiring including tungsten (W).

The composition for etching a TiN film of the present invention is characterized in that the selective etching ratio of the TiN film to the metal film or metal wiring containing tungsten (W) is 7:1 or more.

In the composition for etching a TiN film of the present invention, the weight ratio of (A) at least one component selected from sulfuric acid and alkylsulfonic acid and (B) peroxide component is preferably 10:1 to 50:1, and 16:1 to More preferably, it is 35:1. When the weight ratio is out of the range, the TiN/W etch selectivity cannot be realized to be 7 or more, or the etching rate of TiN is too slow to increase the process time, thereby adversely affecting the process throughput.

In the composition for etching a TiN film of the present invention, the (A) at least one component selected from sulfuric acid and alkylsulfonic acid functions to control the etching amount and selectivity of the TiN film quality and the W film quality.

The alkylsulfonic acid may be selected from methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, butanesulfonic acid, and the like, and these may be used alone or in combination of two or more.

Among the components (A), sulfuric acid may be more preferably used.

The (A) at least one component selected from sulfuric acid and alkylsulfonic acid is included in an amount of 75 to 95% by weight, more preferably 80 to 90% by weight, based on the total weight of the composition. When the component is included in an amount of less than 75% by weight, the etch rate of W is increased as the content of peroxide and water is relatively increased, and a problem occurs that the etch selectivity of TiN/W is lowered, and when it exceeds 95% by weight, the etch rate of TiN is increased is too slow to cause a problem in terms of process yield, which is undesirable.

In the present invention, the peroxide (B) increases the etch rate of TiN and oxidizes the tungsten film to control the etch rate of the tungsten film as needed in the process.

As the peroxide, hydrogen peroxide (H ₂ O ₂ ), tert-butylhydroperoxide, lauroyl peroxide, tert-butylperacetate, tert-butylperoxybenzoate, 2-butane peroxide, methylethylketone peroxide , benzoyl peroxide, dicumyl peroxide, etc. may be selected, and these may be used alone or in combination of two or more.

Among the peroxides, hydrogen peroxide may be more preferably used.

The (B) peroxide is included in an amount of 0.3 to 10% by weight, more preferably 1 to 5% by weight, based on the total weight of the composition. When the component is included in an amount of less than 0.3% by weight, the etching rate of TiN becomes too slow, which causes a problem in terms of process yield, and when it exceeds 10% by weight, selective etching of the TiN film becomes difficult, which is not preferable.

In the present invention, the auxiliary oxidizing agent (C) is an oxidizing agent in which the peroxide plays an auxiliary role in removing the TiN film, and improves the selectivity because it does not affect the etching of W while improving the etching performance of TiN.

The (C) auxiliary oxidizing agent is included in an amount of 0.0005 to 3% by weight, more preferably 0.001 to 1% by weight, based on the total weight of the composition.

When the content of the auxiliary oxidizer is less than 0.0005 wt %, it is difficult to improve the TiN etch performance, and on the contrary, when it exceeds 3 wt %, the etching performance of the W film is increased, thereby reducing the overall selectivity. In particular, when the persulfates are included in an amount exceeding 3% by weight, precipitation may occur in the composition.

In the auxiliary oxidizing agent, examples of the persulfates include ammonium persulfate, sodium persulfate, potassium persulfate, and the like.

Examples of the N-oxide compound represented by Formula 1 include methylmorpholine N-oxide, trimethylamine N-oxide, and the like.

In the detergent composition of the present invention, (D) water is not particularly limited, but it is preferable to use deionized water, and to use deionized water having a specific resistance value of 18㏁/cm or more showing the degree of removal of ions in the water. more preferably.

To the composition for etching TiN of the present invention, a conventional additive may be further added in addition to the above-mentioned components, and the additive may include a corrosion inhibitor, a metal ion sequestering agent, a surfactant, and the like. In addition, the additive is not limited thereto, and in order to further improve the effect of the present invention, various other (E) additives known in the art may be selected and used.

(A) at least one selected from sulfuric acid and alkylsulfonic acid, (B) peroxide, (C) auxiliary oxidizing agent, (E) additive, etc. used in the present invention can be prepared by a commonly known method, The etching composition of the present invention preferably has a purity for semiconductor processing.

The present invention also includes a metal film or metal wiring containing tungsten (W) as a lower metal film or metal wiring, and in a method of forming a metal wiring using a TiN film as a hard mask,

and selectively etching the TiN hardmask with respect to the metal film or metal wiring containing tungsten (W), wherein the etching step is performed using the etchant of the present invention. it's about how

The contents described with respect to the composition for etching TiN may be directly applied to the method of forming the metal wiring.

In the method of forming the metal wiring, the selective etch ratio of the upper TiN hardmask to the lower metal layer including tungsten or the metal wiring is 7:1 or more.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are provided to explain the present invention in more detail, and the scope of the present invention is not limited by the following examples. The following examples can be appropriately modified and changed by those skilled in the art within the scope of the present invention.

Example 1 to 10 comparative example 1-5 TiN film for etching Preparation of the composition

Compositions for etching TiN films of Examples 1 to 10 and Comparative Examples 1 to 5 were prepared by mixing the components shown in Table 1 in the corresponding content. In the following Examples and Comparative Examples, 96% sulfuric acid and 31% fruit water were used as sulfuric acid and fruit water, and their contents were calculated as the contents (Net content) of pure sulfuric acid and fruit water and are shown in Table 1 below.

Sulfuric acid/alkylsulfonic acid Fruit/peroxide auxiliary oxidizing agent DIW type content(%) type content(%) type content(%) content(%) Example 1 sulfuric acid 87.5 fruit tree 2.5 NMMO 0.01 9.99 Example 2 sulfuric acid 87.5 fruit tree 2.5 APS 0.01 9.99 Example 3 sulfuric acid 87.5 fruit tree 2.5 NMMO 0.001 9.999 Example 4 sulfuric acid 87 fruit tree 2.5 NMMO One 9.5 Example 5 sulfuric acid 80 fruit tree 5 NMMO 0.01 14.99 Example 6 sulfuric acid 95 fruit tree 1.9 NMMO 0.01 3.09 Example 7 sulfuric acid 87.5 fruit tree 2.5 TMAO 0.01 9.99 Example 8 sulfuric acid 87.5 TBHP 2.5 APS 0.01 9.99 Example 9 MSA 87.5 fruit tree 2.5 APS 0.01 9.99 Example 10 MSA 87.5 MEKP 2.5 NMMO 0.01 9.99 Comparative Example 1 sulfuric acid 87.5 fruit tree 2.5 - - 10 Comparative Example 2 sulfuric acid 83.5 fruit tree 2.3 APS 5 9.2 Comparative Example 3 sulfuric acid 70 fruit tree 2.5 NMMO 0.01 27.49 Comparative Example 4 sulfuric acid 96 fruit tree - NMMO 0.01 3.99 Comparative Example 5 sulfuric acid 87.5 fruit tree 2.5 TMAH 0.01 9.99

(unit weight %)

[main]

APS: Ammonium Persulfate

NMMO: N-methylmorpholine N-oxide compound

TMAO: trimethylamine N-oxide compound

MSA: methanesulfonic acid

TBHP: tert-butyl hydroperoxide

MEKP: methyl ethyl ketone peroxide

TMAH: tetramethylammonium hydroxide

test example : Etching Characteristics evaluation

The TiN, W, SiNx, SiOx, poly Si, and HfOx substrates were immersed in the etching compositions of Examples 1 to 10 and Comparative Examples 1 to 5 at 75° C. for 5 minutes. The etching rate for the film quality of each substrate was determined by measuring the change in film thickness using an ellipsometer (SE-MG-1000), and the results are shown in Table 2 below. In addition, the unit of the numerical value described below is Å/min.

division TiN W TiN/W SiNx SiOx Poly Si HfOx TEOS Solubility Example 1 57.0 7.0 8.1 <0.1 <0.1 <0.1 <0.1 <0.1 Good Example 2 56.0 7.0 8.0 <0.1 <0.1 <0.1 <0.1 <0.1 Good Example 3 52.0 7.0 7.4 <0.1 <0.1 <0.1 <0.1 <0.1 Good Example 4 59.0 8.0 7.3 <0.1 <0.1 <0.1 <0.1 <0.1 Good Example 5 102.0 14.0 7.2 <0.1 <0.1 <0.1 <0.1 <0.1 Good Example 6 21.0 3.0 7.0 <0.1 <0.1 <0.1 <0.1 <0.1 Good Example 7 56.2 7.2 7.8 <0.1 <0.1 <0.1 <0.1 <0.1 Good Example 8 42.0 4.6 9.1 <0.1 <0.1 <0.1 <0.1 <0.1 Good Example 9 25.2 3.3 7.6 <0.1 <0.1 <0.1 <0.1 <0.1 Good Example 10 17.2 2.0 8.6 <0.1 <0.1 <0.1 <0.1 <0.1 Good Comparative Example 1 45.0 8.0 5.6 <0.1 <0.1 2.0 <0.1 <0.1 Good Comparative Example 2 58.0 8.0 7.2 <0.1 <0.1 <0.1 <0.1 <0.1 precipitation Comparative Example 3 87.0 15.0 5.8 <0.1 <0.1 <0.1 <0.1 <0.1 Good Comparative Example 4 4.0 0.8 5.0 <0.1 <0.1 <0.1 <0.1 <0.1 Good Comparative Example 5 40.0 7.2 5.5 <0.1 <0.1 <0.1 <0.1 <0.1 Good

(Unit: Å/min)

According to Table 2, the compositions for etching the TiN film of Examples 1 to 10 not only realized an etching rate of a certain amount or more for the TiN film and the W film, but also had an etching selectivity of TiN/W of 7 or more, and the main film quality of the semiconductor. It was confirmed that there was no change in film thickness before and after composition treatment of low-k films such as SiNx, SiOx, poly Si, HfOx, and TEOS. In particular, in the case of Examples 1, 2, 8 and 10, the TiN/W etch selectivity was 8 or more, indicating an excellent effect among the Examples.

On the other hand, in Comparative Example 1, Comparative Example 3, Comparative Example 4, and Comparative Example 5, the desired TiN/W selectivity could not be achieved. In the case of Comparative Example 2, the desired etching characteristics were implemented, but there was a problem in that APS was precipitated when a single tool was applied. In the case of Comparative Example 4, it was confirmed that the etching rate of TiN was too slow.

Claims (9)

with respect to the total weight of the composition,
(A) 75-95 wt% of at least one selected from sulfuric acid and alkylsulfonic acid,
(B) 0.3 to 10% by weight of peroxide;
(C) 0.0005 to 3 wt% of at least one auxiliary oxidizing agent selected from the group consisting of persulfates and N-oxide compounds represented by the following formula (1), and
(D) A composition for etching a TiN film comprising a residual amount of water:
[Formula 1]

In the above formula,
R1 to R3 may each independently be a C1-C4 alkyl group,
R2 and R3 may be combined with each other to form a C4~C6 heterocyclic ring with the nitrogen atom present. The method according to claim 1,
The composition for etching the TiN film is used for selectively etching the TiN film in the presence of a metal film or metal wiring containing tungsten (W). The method according to claim 1,
A composition for etching TiN, characterized in that the selective etching ratio of the TiN film to the metal film or metal wiring containing tungsten (W) is 7:1 or more. The method according to claim 1,
TiN film etchant composition, characterized in that the weight ratio of the component (A) and component (B) is 10:1 to 50:1. The method according to claim 1,
Alkylsulfonic acid is a TiN film etchant composition, characterized in that at least one selected from the group consisting of methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and butanesulfonic acid. The method according to claim 1,
Peroxide is hydrogen peroxide (H ₂ O ₂ ), tert-butylhydroperoxide, lauroyl peroxide, tert-butylperacetate, tert-butylperoxybenzoate, 2-butane peroxide, methylethylketone peroxide, benzoyl TiN film etchant composition, characterized in that at least one selected from the group consisting of peroxide, and dicumyl peroxide. The method according to claim 1, wherein the persulfates are selected from the group consisting of ammonium persulfate, sodium persulfate, and potassium persulfate;
The N-oxide compound represented by Formula 1 is a TiN film etchant composition, characterized in that it is selected from the group consisting of a methylmorpholine N-oxide compound and a trimethylamine N-oxide compound. The TiN film etchant according to claim 1, wherein in the N-oxide compound represented by Formula 1, the hetero ring further comprises one hetero atom selected from N, O, and S in addition to the nitrogen atom present in the group. composition. In the method of forming a metal wiring including a metal film or metal wiring containing tungsten (W) as a lower metal film or metal wiring, and using a TiN film as a hard mask,
and selectively etching the TiN hardmask with respect to the metal film or metal wiring containing tungsten (W), wherein the etching step is performed using the etchant of any one of claims 1 to 8. A method of forming a metal wiring.