WO2011142600A2

WO2011142600A2 - Photoresist stripper composition

Info

Publication number: WO2011142600A2
Application number: PCT/KR2011/003501
Authority: WO
Inventors: Young Jin Park; Doo Seok Han; Sang Dai Lee; Hyoseop Shin
Original assignee: Enf Technology Co., Ltd.
Priority date: 2010-05-12
Filing date: 2011-05-12
Publication date: 2011-11-17
Also published as: TWI545190B; CN102893218B; KR101169332B1; JP5590364B2; WO2011142600A3; TW201204828A; CN102893218A; JP2013527992A; KR20110124955A

Abstract

A photoresist stripper composition comprising 0.5 to 5 % by weight of alkyl ammonium hydroxide; 60 to 90 % by weight of aprotic polar solvent; 0.1 to 3 % by weight of aromatic polyhydric alcohol; 0.1 to 5 % by weight of linear polyhydric alcohol; and 5 to 30 % by weight of water has an excellent capacity for stripping a positive and a negative photoresists, and dose not corrode a metal wiring under the photoresist.

Description

PHOTORESIST STRIPPER COMPOSITION

Technical Field

The present invention relates to a photoresist stripper composition for removing a photoresist in the manufacturing process of a semiconductor, LED or LCD device.

Background Art

Generally, a microcircuit semiconductor, LED or LCD device is produced through a series of lithography processes. The lithography process comprises the steps of fomiing a metal layer or an insulating layer, etc. on a substrate; spreading a photoresist on the metal layer; forming a desired pattern of photoresist by selectively exposing the photoresist to light through a patterned mask; and developing process. In the process, the pattern of the metal layer or the insulating layer is formed by dry or wet etching using said photoresist pattern as a mask, and then the photoresist pattern is removed by stripping process.

Photoresists are classified into two types, i.e., positive photoresists and negative photoresists according to the change in solubility to developer upon exposure to light. The positive photoresist is a type of photoresist in which the exposed portion of the photoresist becomes soluble to the developer, and the negative photoresist is a type of photoresist in which the exposed portion of the photoresist becomes insoluble to the developer.

The positive photoresist can be easily removed by using common strippers in general wet processes. However, it is difficult to remove the photoresist, when it is hardened or denatured during a dry etching or an ion implantation process. The dry etching process is preferred for fomiing a micro pattern due to the ease of pattern control and ability to produce anisotropic pattern transfer. However, the dry etching process uses gas-solid reactions between the plasma gas and material layers like conducting layers, and resultingly, ions and radicals of the plasma gas react with the photoresist, and thereby the photoresist is hardened and denatured. Further, the ion implantation in the manufacturing process of the semiconductor, LED or LCD device is a process to bring dopant atoms such as P, As, B, etc. into a desired region of silicon wafers in order to give the conductivity, and therefore, the positive photoresist can be denatured by chemical reaction with the ions.

Meanwhile, negative photoresists are used for a lift-off process. The portion of negative photoresist exposed to light becomes insoluble by crosslinking and therefore cannot be removed completely by using a common solvent and the cleaning process should be performed under severe conditions such as a high temperature over 100^°C and a long dipping time.

A variety of aqueous strippers have been suggested for removing a hardened and denatured photoresist during the dry etching or the ion implantation process. For example, there have been reported a stripper composition comprising hydroxylamines, alkanolamines and water (JP Patent Publication No. 1992-289866); a stripper composition comprising hydroxylamines, alkanolamines, water and a corrosion inhibitor (JP Patent Publication No. 1994-266119); a stripper composition comprising polar solvents (such as gamma-butyrolactone, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc.), amino alcohols (such as 2-methylaminoethanol) and water (JP Patent Publication No. 1995-69618); a stripper composition comprising alkanolamines (such as monoethanolamine/amino ethoxy ethanol), hydroxylamine, diethyleneglycol monoalkyl ether, saccharides(sorbitol) and water (JP Patent Publication No. 1997- 152721); and a stripper composition comprising hydroxylamines, water, amines having pKa 7.5-13, a water-soluble organic solvent and a corrosion inhibitor (JP Patent Publication No. 1997-96911). However, said compositions do not have an enough ability to strip negative photoresists, although they are useful for stripping the crosslinked or denatured positive photoresists.

Acid strippers or alkaline strippers have been conventionally used for removing negative photoresists. A stripper comprising alkylbenzenesulfonates, phenol compounds, chlorinated solvents and aromatic hydrocarbons is a representative acid stripper, but its ability to strip negative photoresists is not sufficient. Further, an alkaline stripper comprising water soluble organic amines and organic solvents, not only has poor capabilities of stripping negative photoresists, but also causes corrosion of metals.

In order to solve this problem, a stripper composition comprising hydrazine, polar organic solvents, alkaline compounds and water has been suggested in KR Patent No. 718527. However, although the compound has a good capacity of stripping negative photoresists, its ability to inhibit corrosion of metal wirings under the photoresist is not enough.

Recently, as the processes for manufacturing semiconductor, LED and LCD devices become much more delicate and complicated, the processes may employ both positive and negative photoresists. Accordingly, if there is no common stripper for both positive and negative photoresists, separate strippers and processing equipments will be required, causing increases in manufacturing costs and time. Therefore, a stripper composition which can efficiently remove both the positive and negative photoresists without causing corrosion of metal wirings under the photoresist layer is required.

Summary of Invention Accordingly, it is an object of the present invention to provide a stripper composition which has an excellent capacity for stripping a positive photoresist and a negative photoresist and dose not corrode a metal wiring under a photoresist layer.

In accordance with one aspect of the present invention, there is provided a photoresist stripper composition comprising 0.5 to 5 % by weight of an alkyl ammonium hydroxide; 60 to 90 % by weight of an aprotic polar solvent; 0.1 to 3 % by weight of an aromatic polyhydric alcohol; 0.1 to 5 % by weight of a linear polyhydric alcohol; and 5 to 30 % by weight of water.

The photoresist stripper composition according to the present invention has an excellent capacity for stripping a positive photoresist hardened and denatured by a dry etching or ion implantation process and a negative photoresist used in a lift-off process, and it does not corrode a metal wiring under a photoresist layer in a stripping process and an ultrapure water rinsing process.

Best Mode for Carrying Out the Invention

Exemplary alkyl ammonium hydroxide for use in the composition of the present invention includes tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide and a mixture thereof. The positive photoresists hardened and denatured by a dry etching, etching or ion implantation process, and the negative photoresists crosslinked during a light exposure process does not dissolve in a solvent due to the crosslinkages therein. Accordingly, it is necessary to change the crosslinked photoresists to soluble forms by using an alkaline constituent for cutting the crosslinkages.

The content of alkyl ammonium hydroxide is preferably 0.5 to 5 % by weight based on the total weight of the composition. If the content of alkyl ammonium hydroxide is less than 0.5 % by weight, the efficiency of removing photoresists becomes lower because it is difficult to cut the denatured and crosslinked polymer chains; and if it exceeds 5 % by weight, the relative content of aprotic polar solvent becomes decrease, thereby the solubility of the photoresist and increasing the corrosion of the underlying metallic film.

The aprotic polar solvent of the composition of the present invention may be N,N-dimethylformamide, Ν,Ν-dimethylacetamide, Ν,Ν'- diethylacetamide, dimethylsulfoxide, N-methylformamide, Ν,Ν'- dimethyllactamamide, N-methylpyrrolidone, γ -butyrolactone, propylene carbonate, l ,3-dimethyl-2-imidazolidinone and a mixture thereof.

The content of the aprotic polar solvent may be 60 to 90 % by weight based on the total weight of the composition. If the content of aprotic polar solvent is less than 60 % by weight, dissolvability for photoresist decreases; and if it exceeds 90 % by weight, the relative content of water decreases, thereby lowering the activity of alkyl ammonium hydroxide and decreeing the capacity for stripping the denatured or crosslinked positive and negative photoresists.

The content of water in the composition preferably ranges from 5 to 30 % by weight based on the total weight of the composition. If the content of water is less than 5 % by weight, the degree of dissociation of alkyl ammonium hydroxide becomes lower, resulting in the decrease in the capacity for stripping the denatured or crosslinked positive and negative photoresists. If the content of water exceeds 30 % by weight, the activity of alkyl ammonium hydroxide becomes too high, thereby causing insufficient corrosion inhibiting ability for the underlying metallic film.

Among the main constituents of the inventive composition, the aromatic polyhydric alcohol and the linear polyhydric alcohol act as a corrosion inhibitor.

The content of the aromatic polyhydric alcohol may be 0.1 to 3 % by weight based on the total weight of the composition. If the content of the aromatic polyhydric alcohol is less than 0.1 % by weight, the corrosion inhibiting ability for the underlying metallic film decreases; and if it exceeds 3 % by weight residual corrosion inhibitor itself would cause a defect in the subsequent processes.

The content of the linear polyhydric alcohol may be 0.1 to 5 % by weight based on the total weight of the composition. If the content of the linear polyhydric alcohol is less than 0.1 % by weight, the corrosion inhibiting ability for the underlying metallic film decreases; and if it exceeds 5 % by weight residual corrosion inhibitor itself would cause a defect in the subsequent processes.

The aromatic polyhydric alcohol and the linear polyhydric alcohol preferably have at least three hydroxyl groups. If the number of hydroxyl groups is less than three, the adsorptivity of such alcohols to metal surface becomes lower, which may cause insufficient corrosion inhibiting ability. Further, the aromatic polyhydric alcohol corrosion inhibitor preferably has at least one carboxyl group or alkylester group. If the number of carboxyl group or alkylester group is less than one, the migration of such alcohols to the surface of a metal decreases, which may cause insufficient corrosion inhibiting ability.

Examples of the aromatic polyhydric alcohol include gallic acid, methyl gallate, ethyl gallate, propyl gallate, butyl gallate and a mixture thereof, and examples of the linear polyhydric alcohol may be glycerol, erythritol, sorbitol, mannitol, xylitol and a mixture thereof.

The composition of the present invention exhibits an excellent corrosion inhibiting effect owing to a synergistic effect obtained by the combined use of the aromatic polyhydric alcohol and the linear polyhydric alcohol. In order to remove a denatured and crosslinked photoresist, an alkaline compound such as alkyl ammonium hydroxide is required, and addition of the alkaline compound to a stripper composition increases pH of composition. A high pH composition causes the corrosion of the underlying metallic film in the stripping and the rinsing processes, so a corrosion inhibitor is required. In a high pH condition, the aromatic polyhydric alcohol and the linear polyhydric alcohol exhibit superior corrosion inhibiting abilities.

Generally, inhibition of corrosion is achieved by the adsorption of a corrosion inhibitor to the surface of metal. Upon adsorption, a number of the corrosion inliibitors are adsorbed to the metal surface to form a molecular layer thereon. The performance of the corrosion inhibitor depends on an adsorptive power to the metal surface and the density of the molecular layer, and the corrosion inhibiting performance becomes higher as the adsorptive power and the density of the molecular layer increase.

The aromatic polyhydric alcohol corrosion inhibitor forms a resonance structure with a benzene ring while dissociating the hydrogen atoms from its hydroxyl groups, and accordingly, it is adsorbed to metal as an inflexible platy structure. The linear polyhydric alcohol corrosion inhibitor does not form a resonance structure, even if the hydrogen atoms in its hydroxyl groups are dissociated, and accordingly, it is adsorbed to metal as a flexible chain structure. Therefore, the linear polyhydric alcohol has the merit of being adsorbing to a minute part owing to its small adsorption area, although it has a low adsorptive power. As the tendency of corrosion inhibitor in stripper to move to metal surface (the surface migration) is greater, the number of corrosion inhibitor adsorbed on the metal surface increases, resulting in a higher corrosion inhibiting ability.

The aromatic polyhydric alcohol and the linear polyhydric alcohol exhibit different corrosion inhibition characteristics due to the difference in their metal adsoiptive structures. The aromatic polyhydric alcohol corrosion inhibitor can adsorb strongly to a metal surface due to its platy resonance structure, while it has a low density of molecular layer due to the inflexible structure. A linear polyhydric alcohol corrosion inhibitor has a high density of molecular layer due to its flexible chain structure, but it can not adsorb strongly to a metal surface because such structure can not adsorb to metal strongly.

To achieve an excellent corrosion inhibition, a corrosion inhibitor should strongly adsorb to a metal surface and the density of a molecular layer formed thereby should be higher. A combined use of the aromatic polyhydric alcohol and the linear polyhydric alcohol provides a preferable corrosion inhibition over the entire metal layer with maintaining the capacity for stripping the photoresist, owing to the strong adsorption capability of the aromatic polyhydric alcohol to metal and the capability of the linear polyhydric alcohol adsorbing to minute parts where the aromatic polyhydric alcohol can not be adsorbed. In contrast, the excellent corrosion inhibition with the maintenance of the capacity for stripping the photoresist can not be obtained when the aromatic polyhydric alcohol or the linear polyhydric alcohol is used alone. When used alone, a lot of corrosion inhibitor is required to obtain the desired corrosion inhibiting ability, which decrease the relative content of a polar solvent, thereby lowering the capacity of the stripper composition for solubilizing the photoresist, or makes it difficult to use the composition due to the low solubility of the corrosion inhibitor in composition.

The composition of the present invention may further contain glycols and triazoles in accordance with a desired object, as long as the effects of the present invention are not degraded.

Suitable glycols include, but are not limited to, diethyleneglycol methylether, diethyleneglycol ethylether, diethyleneglycol butylether, dipropyleneglycol methylether, hexylene glycol, polyethylene glycol having a weight-average molecular weight ranging from 100 to 400, etc., and suitable triazols include, but are not limited to, benzotriazole, carboxybenzotriazole, 1- hydroxybenzotriazole, nitrobenzotriazole, dihydroxypropylbenzotriazole, etc. As described above, the photoresist stripper composition according to the present invention has an excellent capacity for stripping a positive photoresist hardened and denatured by a dry etching or ion implantation process and a negative photoresist used in a lift-off process, and it does not corrode a metal wiring under a photoresist layer in a stripping process and an ultrapure water rinsing process. Particularly, an excellent corrosion inhibiting effect can be obtained with only a small amount of the corrosion inhibitor without decreasing the capacity for stripping the photoresist, owing to a synergistic effect resulted from the aromatic polyhydric alcohol corrosion inhibitor and the linear polyhydric alcohol corrosion inhibitor.

Examples

Hereinafter, the following Examples are intended to further illustrate the present invention without limiting its scope.

Examples 1 to 9 and Comparative Examples 1 to 21

Compositions of Examples 1 to 9 and Comparative Examples 1 to 21 were prepared by mixing the constituents as set forth in Table 1.

The mixing is carried out 1 hr or more under a room temperature to thoroughly dissolve the solid corrosion inhibitors, and then filtered through a teflon filter.

Experimental Example

A stripping capacity and a corrosion inhibiting ability of the compositions obtained in Examples 1 to 9 and Comparative Examples 1 to 21 were evaluated as follows.

(1) Preparation of a positive photoresist specimen. A positive photoresist(THMR-iP 3300, TOK) was coated on a silicon nitride-coated silicon wafer, followed by exposure and developing processes to form a photoresist pattern. The pattern was transferred to silicon nitride layer under the photoresist by dry etching process to obtain the positive photoresist specimen.

(2) Preparation of a negative photoresist specimen.

A negative photoresist(PMER N-HC600, TOK) was coated on a silicon wafer, followed by exposure, developing and baking processes to form a photoresist pattern. Aluminum and titanium were sequentially spread on the silicon wafer to obtain a lift-off negative photoresist specimen.

Test Example 1. Evaluation of stripping capacity

The test composition was maintained at 60 ^°C , and the positive photoresist specimen and the negative photoresist specimen were immersed therein for 20 min, rinsed with a deionized water for 30 sec, and then dried by nitrogen. The residual photoresist in the dried specimen was observed under an optical microscope (magnification: x200) and a FE-SEM (magnification:

10,000 - x50,000).

Test Example 2. Evaluation of corrosion inhibiting ability

The test composition was maintained at 60 ^°C , and the negative photoresist specimen was immersed therein for 90 min. The resulting specimen was rinsed with deionized water for 30 sec, and then dried by nitrogen for 10 sec. Degrees of corrosion at the surface and the cross section of the dried specimen were observed under a FE-SEM (magnification: 10,000 ~ x 50,000). In this test example, a corrosion condition harsher than the common stripping condition of 20 min was employed in order to find out differences in the degree of corrosion. Table 1

As can be seen from Table 1 , Examples 1 to 9 in accordance with the present invention exhibited an excellent capacity for stripping the positive and the negative photoresists, and did not corrode Al/Ti, the lower metallic film. Whereas, Comparative Examples 1 to 21 beyond the scope of the present invention exhibited low stripping capacities and increased corrosion.

While the invention has been described with respect to the above specific embodiments, it should be recognized that various modifications and changes may be made by those skilled in the art to the invention which also fall within the scope of the invention as defined by the appended claims.

Claims

What is claimed is :

1. A photoresist stripper composition comprising:

0.5 to 5 % by weight of alkyl ammonium hydroxide;

60 to 90 % by weight of aprotic polar solvent;

0.1 to 3 % by weight of aromatic polyhydric alcohol;

0.1 to 5 % by weight of linear polyhydric alcohol; and

5 to 30 % by weight of water.

2. The photoresist stripper composition according to claim 1 , wherein the aromatic polyhydric alcohol comprises at least one carboxyl group or alkylester group, and at least three hydroxyl groups.

3. The photoresist stripper composition according to claim 1 , wherein the aromatic polyhydric alcohol is selected from the group consisting of gallic acid, methyl gallate, ethyl gallate, propyl gallate, butyl gallate and a mixture thereof.

4. The photoresist stripper composition according to claim 1 , wherein the linear polyhydric alcohol comprises at least three hydroxyl groups.

5. The photoresist stripper composition according to claim 1 , wherein the linear polyhydric alcohol is selected from the group consisting of glycerol, erythritol, sorbitol, mannitol, xylitol and a mixture thereof.

6. The photoresist stripper composition according to claim 1 , wherein the alkyl ammonium hydroxide is selected from the group consisting of tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide and a mixture thereof.

7. The photoresist stripper composition according to claim 1 , wherein the aprotic polar solvent is selected from the group consisting of N,N- dimethylformamide, Ν,Ν-dimethylacetamide, N,N'-diethylacetamide, dimethylsulfoxide, N-methylformarnide, Ν,Ν'-dimethyllactamamide, N- methylpyrrolidone, γ -butyrolactone, propylene carbonate, l ,3-dimethyl-2- imidazolidinone and a mixture thereof.

8. The photoresist stripper composition according to claim 1, which further comprises glycols and triazoles.

9. The photoresist stripper composition according to claim 8, wherein the glycol is selected from the group consisting of diethyleneglycol methylether, diethyleneglycol ethylether, diethyleneglycol butylether, dipropyleneglycol methylether, hexylene glycol, polyethylene glycol having a weight-average molecular weight ranging from 100 to 400 and a mixture thereof.

10. The photoresist stripper composition according to claim 8, wherein the triazoles is selected from the group consisting of benzotriazole, carboxybenzotriazole, 1-hydroxybenzotriazole, nitrobenzotriazole, dihydroxypropylbenzotriazole and a mixture thereof.