KR20230127692A - Stripper composition for metal oxide layer - Google Patents

Abstract

The present invention provides a metal oxide film stripper composition comprising an organic solvent, an inorganic acid and an alkylammonium fluoride, wherein the inorganic acid is included in an amount of 0.05 to 0.5% by weight based on the total weight of the composition.

Description

Metal oxide film stripper composition {STRIPPER COMPOSITION FOR METAL OXIDE LAYER}

The present invention relates to a stripper composition effective for removing a metal oxide film.

In general, in order to manufacture a semiconductor device, several stages of metal wiring processes must be performed. In particular, as the degree of integration of semiconductor devices is gradually increasing, the structure of metal wiring is also becoming increasingly multilayered.

In order to form a metal wiring having a multilayered structure, an insulating film, for example, a silicon oxide film is formed on a lower metal film to be contacted. Then, the silicon oxide layer is etched to form a contact hole exposing a predetermined surface of the lower metal layer, and then a thin barrier layer is formed in the contact hole. Then, an upper metal film is formed on the barrier layer so that the upper metal film completely fills the contact hole. Then, the upper metal film is patterned using a mask film pattern, for example, a photoresist film pattern.

In general, when an aluminum layer is used as the upper metal layer, an etching process for patterning the aluminum layer is performed using an etching facility using high-density plasma. That is, after loading a semiconductor wafer coated with an aluminum film into the high-density plasma etching equipment, upper and lower radio frequency (RF) power is supplied. Then, the aluminum film is etched using high-density plasma formed on the semiconductor wafer by supplying a reaction gas.

However, as a result of the aluminum film etching process as described above, an aluminum oxide film and aluminum residue are formed, and various problems arise from them, so it is necessary to remove them.

Republic of Korea Patent Publication No. 10-2014-0074966 discloses residues after plasma etching, such as but not limited to titanium-containing residues, polymer sidewall residues, copper-containing via residues, tungsten-containing residues and/or cobalt-containing residues. As an improved composition for effective removal from microelectronic devices, a composition that is compatible with IDLs, metal interconnect materials and/or capping layers is disclosed. However, there are problems in that the storage stability may be deteriorated due to the silica source, and the removal performance of metal oxide films such as aluminum oxide films and aluminum residues is not sufficient.

Republic of Korea Patent Publication No. 10-2014-0074966

An object of the present invention is to provide a metal oxide film stripper composition that effectively removes a metal oxide film while suppressing damage to a lower metal film and a silicon oxide film.

In order to achieve the above object, the present invention provides a metal oxide film stripper composition comprising an organic solvent, an inorganic acid and an alkylammonium fluoride.

The stripper composition of the present invention provides an effect of effectively removing a metal oxide film with only a small amount of alkyl ammonium fluoride through the addition of an inorganic acid.

In addition, the stripper composition of the present invention provides an effect of minimizing damage to the lower metal film and the silicon oxide film while being able to remove aluminum residues.

Hereinafter, the present invention will be described in detail.

The metal oxide film stripper composition of the present invention includes an organic solvent, an inorganic acid, and an alkylammonium fluoride, and may additionally contain water.

The metal oxide layer may be an aluminum oxide layer.

The metal oxide film stripper composition may have an etching rate of 20 Å/min or more and less than 40 Å/min for the aluminum oxide film.

A root mean square (RMS) roughness of a surface of an aluminum oxide film etched using the metal oxide film stripper composition may be less than 10 Å.

In addition, the metal oxide film stripper composition can prevent damage to the lower metal film and the silicon oxide film, and the lower metal film may include a metal film including copper, tungsten, molybdenum, cobalt, and the like.

Hereinafter, each component included in the metal oxide film stripper composition of the present invention will be described.

organic solvent

The stripper composition of the present invention contains an organic solvent and, unlike an aqueous composition using water as a solvent, it is possible to control the dissolution rate of a metal oxide film such as an aluminum oxide film, thereby realizing a reduced etching rate.

As the organic solvent, an aprotic polar solvent or a protic polar solvent may be used.

Specific examples of the aprotic polar solvent include carbonate-based organic solvents such as propylene carbonate and ethylene carbonate; a sulfone-based organic solvent composed of dimethyl sulfoxide, dimethylsulfone, diethylsulfone, methylsulfolane, and sulfolane; or lactone-based organic solvents such as γ-butylolactone and delta-valerolactone; And it may include at least one selected from the group consisting of ketone-based organic solvents such as diethyl ketone.

Specific examples of the protic polar solvent include alcohols, glycols, and glycol ethers. Specific examples of the alcohol include linear alcohols such as ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, and decanol, and 1,4-butanediol and 1,5-pentanediol , Diols such as 1,6-hexanediol, and branched alcohols such as isopropyl alcohol, 1-ethoxy-2-propanol, and 4-methyl-2-pentanol. The glycols include ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, diethylene glycol, dipropylene glycol, and the like. The glycol ethers may include at least one selected from the group consisting of diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, and triethylene glycol monobutyl ether.

The content of the organic solvent is not particularly limited, but may be included in 60 to 99.75% by weight, preferably 80 to 99.6% by weight, based on the total weight of the composition. When the above range is satisfied, an appropriate etching rate can be exhibited for a metal oxide film such as an aluminum oxide film, which is preferable.

inorganic acid

The inorganic acid included in the stripper composition of the present invention performs a role of chelating a metal to remove a metal oxide film such as an aluminum oxide film and residues after etching, and maintaining the pH in an acidic region.

The inorganic acid may include at least one selected from the group consisting of nitric acid, hydrochloric acid, phosphoric acid, and sulfuric acid, and more preferably, at least one selected from nitric acid and hydrochloric acid.

The inorganic acid is preferably included in an amount of 0.05 to 0.5% by weight, more preferably 0.05 to 0.2% by weight, based on the total weight of the composition. When the amount of the inorganic acid is less than 0.05% by weight, the etching rate of a metal oxide film such as an aluminum oxide film is reduced, and when the amount exceeds 0.5% by weight, the etching rate is increased, causing damage to the silicon oxide film and the lower metal film.

Alkylammonium fluoride

Alkylammonium fluoride included in the stripper composition of the present invention serves to provide fluoride ions (F ^- ) for removing metal oxide films such as aluminum oxide films.

Since the alkylammonium fluoride has an alkyl group bonded to a nitrogen atom, the etching rate of the silicon oxide film can be controlled, and among halogen ions, when fluoride ions are used, the aluminum chelate formation effect is the best, so it is preferable.

Specific examples of the alkylammonium fluoride may include at least one selected from the group consisting of tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride, and tetrabutylammonium fluoride.

The alkylammonium fluoride is preferably included in an amount of 0.1 to 1% by weight, more preferably 0.2 to 0.5% by weight, based on the total weight of the composition. When the alkylammonium fluoride content satisfies the above content range, an appropriate etching rate can be exhibited for a metal oxide film such as an aluminum oxide film, and damage to a lower metal or silicon oxide film can be prevented, which is preferable.

water

The water included in the stripper composition of the present invention may be deionized water for semiconductor processing, and preferably, the deionized water having a concentration of 18 MΩ/cm or more may be used.

In the present invention, water may be included in an amount of 0.1 to 1% by weight based on the total weight of the composition. When water satisfies the above content range, it is preferable because it prevents damage to the underlying metal and silicon oxide film and facilitates etching of metal oxide films such as aluminum oxide films.

Hereinafter, the present invention will be described in more detail through examples and test examples. However, the scope of the present invention is not limited by the following examples and test examples.

Examples 1 to 16 and Comparative Examples 1 to 8: Preparation of stripper composition

A stripper composition was prepared according to the ingredients and composition ratios shown in Table 1 below.

Furtherance
(weight%) organic solvent inorganic acid Fluoride DIW A-1 ¹⁾ A-2 ²⁾ A-3 ³⁾ B-1 ⁴⁾ B-2 ⁵⁾ C-1 ⁶⁾ C-2 ⁷⁾ C-3 ⁸⁾ C-4 ⁹⁾ Example 1 99.25 0.05 0.50 0.20 Example 2 99.59 0.10 0.10 0.21 Example 3 99.11 0.10 0.50 0.29 Example 4 98.51 0.10 1.00 0.39 Example 5 98.00 0.50 0.50 1.00 Example 6 99.65 0.10 0.05 0.20 Example 7 98.27 0.10 1.20 0.43 Example 8 99.11 0.10 0.50 0.29 Example 9 99.11 0.10 0.50 0.29 Example 10 99.33 0.05 0.50 0.12 Example 11 99.25 0.10 0.50 0.15 Example 12 98.68 0.50 0.50 0.32 Example 13 99.25 0.10 0.50 0.15 Example 14 99.25 0.10 0.50 0.15 Example 15 99.53 0.10 0.18 0.19 Example 16 97.90 0.10 0.50 1.50 Comparative Example 1 99.34 0.02 0.50 0.14 Comparative Example 2 97.10 0.80 0.50 1.60 Comparative Example 3 99.57 0.02 0.30 0.11 Comparative Example 4 98.45 0.80 0.30 0.45 Comparative Example 5 99.40 0.50 0.10 Comparative Example 6 99.71 0.10 0.19 Comparative Example 7 99.21 0.10 0.50 0.19 Comparative Example 8 98.96 0.10 0.50 0.44

One) A-1: Propylene carbonate

2) A-2: Isopropyl alcohol

3) A-3: Ethylene glycol

4) B-1: Nitric acid

5) B-2: Hydrochloric acid

6) C-1: Tetrabutyl ammonium fluoride

7) C-2: Tetrametyl ammonium fluoride

8) C-3: Ammonium fluoride

9) C-4: Hydrofluoric acid

Experimental example

Experimental Example 1: Etching Rate Evaluation for Aluminum Oxide Film Quality

Specimens were prepared by cutting a wafer on which an aluminum oxide film was deposited to a thickness of 140 Å on a silicon wafer into a size of 2 × 2 cm. The specimen was immersed in the stripper compositions of Examples and Comparative Examples in a thermostat at 40° C. for 1 minute. Then, the specimen was taken out, washed with water, and dried using N ₂ . The etching rate for the film quality of each substrate was measured by measuring the film thickness before and after immersion using an ellipsometer, and evaluated according to the following evaluation criteria, and the results are shown in Table 2 below.

<Aluminum Oxide Film Etching Rate Evaluation Criteria>

◎: Etch rate of 20 Å/min or more and less than 40 Å/min

○: Etch rate of 10 Å/min or more and less than 20 Å/min

△: Etch rate of 40 Å/min or more

Х: not etched

Experimental Example 2: Etching rate evaluation for silicon oxide film quality

Specimens were prepared by cutting a wafer on which a silicon oxide film was deposited to a thickness of 500 Å on a silicon wafer into a size of 2 × 2 cm. The specimen was immersed in the stripper compositions of Examples and Comparative Examples in a thermostat at 60° C. for 1 minute. Then, the specimen was taken out, washed with water, and dried using N ₂ . The etching rate for the film quality of each substrate was measured by measuring the film thickness before and after immersion using an ellipsometer, and evaluated according to the following evaluation criteria, and the results are shown in Table 2 below.

<Silicon oxide film (protective film material) etching evaluation criteria>

○: Etch rate less than 2 Å /min

△: Etch rate of 2 Å/min or more and less than 4 Å/min

Х: Etch rate of 4 Å/min or more

Experimental Example 3: Evaluation of etching uniformity (surface roughness) of aluminum oxide film

The root mean square (RMS) change of the aluminum oxide film surface of the aluminum oxide film etch rate evaluation specimen was analyzed with an Atomic Force Microscope (AFM). At this time, the evaluation criteria are as follows, and the results are shown in Table 2 below.

<Evaluation Criteria for Aluminum Oxide Film Etching Uniformity>

◎ : RMS less than 10 Å

○: RMS 10 Å or more and less than 15 Å

△: RMS 15 Å or more and less than 20 Å

Х : RMS 20 Å or more

Experimental Example 4: Etching rate evaluation for tungsten

Specimens were prepared by cutting a wafer in which tungsten was deposited to a thickness of 200 Å on a silicon wafer into a size of 3 X 3 cm. The specimen was immersed in the stripper compositions of Examples and Comparative Examples in a thermostat at 40° C. for 1 minute. Then, the specimen was taken out, washed with water, and dried using N ₂ . The etching rate for the film quality of each substrate was measured by measuring the film thickness before and after immersion using XRF, and evaluated according to the following evaluation criteria, and the results are shown in Table 2 below.

<Tungsten (protective film) etching evaluation criteria>

○: Etch rate less than 2 Å /min

△: Etch rate of 2 Å/min or more and less than 4 Å/min

Х: Etch rate of 4 Å/min or higher

division aluminum oxide film
etch rate silicon oxide film
etch rate aluminum oxide film
surface roughness tungsten
etch rate Example 1 ◎ ○ ◎ ○ Example 2 ◎ ○ ◎ ○ Example 3 ◎ ○ ◎ ○ Example 4 ◎ ○ ◎ ○ Example 5 ◎ ○ ◎ ○ Example 6 ○ ○ ◎ ○ Example 7 △ ○ ○ ○ Example 8 ◎ ○ ◎ ○ Example 9 ◎ ○ ◎ ○ Example 10 ◎ ○ ◎ ○ Example 11 ◎ ○ ◎ ○ Example 12 ◎ ○ ◎ ○ Example 13 ◎ ○ ◎ ○ Example 14 ◎ ○ ◎ ○ Example 15 ◎ ○ ◎ ○ Example 16 ◎ △ ◎ △ Comparative Example 1 X ○ ◎ ○ Comparative Example 2 △ X X X Comparative Example 3 X ○ ◎ ○ Comparative Example 4 △ X X X Comparative Example 5 ○ X ◎ ○ Comparative Example 6 X ○ ◎ ○ Comparative Example 7 ○ X ○ X Comparative Example 8 ○ X ○ X

Referring to Table 2, the metal oxide film stripper compositions of Examples 1 to 15 contain 0.05 to 0.5% by weight of an inorganic acid and alkylammonium fluoride based on the total weight of the composition, thereby providing excellent etching rate and uniformity for aluminum oxide film. It can be confirmed that not only the surface roughness can be secured, but also the damage to the silicon oxide film and tungsten, which are protective films, can be prevented. In particular, in the case of Examples 1 to 5 and 8 to 15 containing alkylammonium fluoride in an amount of 0.1 to 1% by weight, it was confirmed that the etching rate and surface roughness characteristics of the aluminum oxide film were more excellent.

On the other hand, in Comparative Example 1 and Comparative Example 3 containing an inorganic acid in an amount of less than 0.05% by weight, the etching rate of the aluminum oxide film was too slow and the metal oxide film was not sufficiently removed. In the case of Comparative Example 5 not containing an inorganic acid, damage to the silicon oxide film could not be prevented. In addition, in Comparative Example 2 and Comparative Example 4 in which the content of the inorganic acid exceeds 0.5% by weight, the etching rate for the aluminum oxide film is too fast, and damage to the silicon oxide film and tungsten, which are protective films, cannot be prevented at all. As the etching rate of the oxide film increased, the surface roughness characteristics thereof were also remarkably deteriorated. In addition, in the case of Comparative Example 6 not containing alkylammonium fluoride, the etching rate of the aluminum oxide film was too slow and the metal oxide film was not sufficiently removed. In addition, in the case of Comparative Examples 7 and 8 using other fluorides that do not contain alkylammonium by replacing the alkylammonium fluoride compound, the silicon oxide film and tungsten are damaged, and the surface roughness characteristics of the aluminum oxide film are also deteriorated. point can be checked.

Claims (9)

A metal oxide film stripper composition comprising an organic solvent, an inorganic acid and an alkylammonium fluoride,
The inorganic acid is contained in 0.05 to 0.5% by weight based on the total weight of the composition, the metal oxide film stripper composition. The method of claim 1,
The metal oxide film stripper composition further comprises 0.1 to 1% by weight of water based on the total weight of the composition. The method of claim 1,
The inorganic acid is a metal oxide film stripper composition comprising at least one selected from the group consisting of nitric acid, hydrochloric acid, phosphoric acid and sulfuric acid. The method of claim 1,
Wherein the alkylammonium fluoride comprises at least one selected from the group consisting of tetramethylammonium fluoride, tetraethylammonium fluoride, tetrapropylammonium fluoride and tetrabutylammonium fluoride. The method of claim 1,
The metal oxide film is an aluminum oxide film, a metal oxide film stripper composition. The method of claim 1,
The organic solvent is contained in 60 to 99.75% by weight based on the total weight of the composition, the metal oxide film stripper composition. The method of claim 1,
The alkylammonium fluoride is included in 0.1 to 1% by weight based on the total weight of the composition, the metal oxide film stripper composition. The method of claim 1,
The metal oxide film stripper composition has an etch rate of 20 Å/min or more and less than 40 Å/min for an aluminum oxide film. The method of claim 1,
The metal oxide film stripper composition, wherein the root mean square (RMS) roughness of the surface of the aluminum oxide film etched using the metal oxide film stripper composition is less than 10 Å.