JP2014048667A - Stripper composition for thick negative photoresist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stripper composition for a photoresist.SOLUTION: The stripper composition for a photoresist comprises: 1 to 5 mass% of a compound expressed by chemical formula (1); 70 to 95 mass% of a polar organic solvent; 0.1 to 5 mass% of a hydroxide-based compound; and the balance water. As the stripper composition particularly does not contain an anticorrosive in the composition but contains an appropriate amount of the compound expressed by chemical formula (1), a stripping process can be efficiently completed in a short time, and thereby, changes in the composition can be minimized in the stripping process that is carried out at a relatively high temperature compared to other processes. As the composition does not contain an anticorrosive, a post-process failure such as vapor deposition failure due to adsorption of a water-insoluble anticorrosive can be prevented as well as damages on an electrode can be prevented.

Description

  The present invention relates to a stripping solution composition capable of effectively removing a thick negative resist.

In general, a fine circuit of a semiconductor / LED / LCD element is completed through a series of lithography processes. In the lithography process, a metal film or an insulating film is uniformly applied to a substrate, and a photoresist is uniformly applied thereon, and then light is irradiated through a mask in which a pattern is engraved, and a desired pattern is developed through a development process. Forming the photoresist. At this time, after transferring the pattern to the metal film and the insulating film below the photoresist by dry / wet etching, unnecessary photoresist is removed by a peeling process.
The photoresist is classified into a positive type photoresist and a negative type photoresist according to a difference in solubility in a developer due to irradiation of radiation. The positive photoresist is developed by increasing the solubility of the exposed portion, and the negative photoresist is reduced in the solubility by curing of the exposed portion and remains as a pattern after development.
In the case of a positive type photoresist, it is easily removed by a general stripping solution in a general wet process, but it becomes difficult to remove if it is cured and modified by dry etching, ion implantation process or the like. Compared with wet etching, the dry etching process has the advantage that the pattern can be easily removed and an anisotropic pattern can be obtained. It is mainly used for the formation of fine patterns. Since the etching process is performed using a gas phase-solid phase reaction with such a material film, the ions and radicals of the plasma etching gas cause a chemical reaction with the photoresist, thereby removing and curing the photoresist film. Becomes difficult. The ion implantation step is a step of diffusing elements such as phosphorus, arsenic, boron, etc. in order to impart conductivity to a specific region of the substrate in the manufacturing process of the semiconductor / LED / LCD element, and the ions are positive type. Since it is modified by causing a chemical reaction with the photoresist, it is still difficult to remove.
On the other hand, in the case of a negative photoresist, it is used in a lift-off process, etc., and is crosslinked by exposure, and cannot be sufficiently removed using a general solvent. Since the immersion at a high temperature of 100 ° C. or higher and the immersion time for a long time are required, it is difficult to stably carry out the removal process.

In general, the photoresist used for the etching process has a film thickness of 2 μm or less, but the photoresist used for the electrode in the bump electrode formation process or the redistribution process (RDL: Redistribution Line) has the thickness. Must be formed with a thickness of 5 μm or more to several tens of μm, a peeling process for removing the photoresist has to be performed for a long time, thereby reducing the process efficiency.
Furthermore, since the photoresist can cause defects in the semiconductor element unless it is removed unevenly by the stripper, the stripper composition used during the photoresist removal process must be able to balance the stripping and dissolving action in a balanced manner. I must.

Various photoresist strippers are known. For example, Korean Patent Application Publication No. 2004-0104033 discloses a photoresist stripping composition composed of monoethanolamine, a glycol compound, a polar solvent and a corrosion inhibitor. The composition has a characteristic that it can peel a positive photoresist but cannot peel a negative photoresist.
Korean Patent Application Publication No. 2007-0019897 discloses a negative photoresist stripping composition composed of hydrazine, a polar organic solvent and a basic compound, but it contains hydrazine which is an environmental management substance. It has the characteristic that process application is difficult.
Korean Patent Application Publication No. 2006-117219 discloses a negative photoresist stripping composition composed of a hydroxide compound, glycols and dimethyl sulfoxide, but the above composition is a negative photoresist. Although it can be peeled off, the process efficiency is low because it takes 60 minutes or more to remove the thick photoresist having a thickness of 120 μm or more.
Korean Patent Registration No. 10-0770217 discloses a photoresist removal composition for bump electrode forming thick film composed of tetramethylammonium hydroxide (TMAH), alkanolamine and a polar organic solvent. The above composition is excellent in peeling force for a thick-film negative photoresist and minimizes damage to the polyimide film, but it is difficult to apply to a process in which the electrode is not protected with polyimide because the corrosion to the metal electrode is fragile. Has the disadvantages.
Meanwhile, Korean Patent Application Publication No. 1997-016636 discloses a stripping composition comprising hydroxylamines, water, amines having an acid dissociation constant (pKa) of 7.5 to 13, a water-soluble organic solvent, and a corrosion inhibitor. Although disclosed, the composition has the disadvantage that wastewater treatment is difficult due to the inclusion of hydroxylamines, which are environmental management substances, and the composition becomes complicated by using an anticorrosive, and these compositions are in the process. It has a demerit that it can cause vapor deposition defects in subsequent processes by adsorption.

Korean Patent Application Publication No. 2004-0104033 Korean Patent Application Publication No. 2007-0019897 Korean Patent Application Publication No. 2006-117219 Korean Patent Registration No. 10-0770217 Korean Patent Application Publication No. 1997-016636

  Accordingly, an object of the present invention is to provide a stripping composition capable of effectively stripping a thick-film negative photoresist in a short time.

According to the above object, the present invention provides 1 to 5% by mass of the compound represented by the chemical formula (1), 70 to 95% by mass of a polar organic solvent, 0.1 to 5% by mass of a hydroxide compound, and the remaining amount. Provided is a photoresist stripping composition containing water.
(In the formula, n is an integer of 2 to 8.)

The photoresist stripping composition according to the present invention performs a short-time stripping process or efficiently removes two thick-film photoresists, resulting in cost savings by shortening the process time, compared to other processes. In the peeling process performed at a relatively high process temperature, the composition change can be minimized. Further, by not containing a corrosion inhibitor, it is possible to prevent a post-process failure such as a vapor deposition failure due to adsorption of a water-insoluble corrosion inhibitor and to prevent electrode damage.

FIG. 1 is an FE-SEM photograph of the surface of a bump electrode according to the stripping solution composition evaluation of Example 1 in the present invention. FIG. 2 is an FE-SEM photograph of the bump electrode surface by the stripping performance evaluation with the stripping solution composition of Comparative Example 1 not according to the present invention. FIG. 3 is an FE-SEM photograph of the bump electrode surface by metal film corrosivity evaluation with the stripping solution composition of Comparative Example 1 not according to the present invention.

  The present invention provides a stripping composition capable of effectively decomposing and removing a thick-film negative photoresist. In the present specification, a thick film means a photoresist film laminated with a thickness exceeding 1 to 2 μm, which is the thickness of a photoresist used in a general lithography process.

The negative photoresist stripping composition according to the present invention comprises 1 to 5% by mass of the compound represented by the chemical formula (1), 70 to 95% by mass of a polar organic solvent, and 0.1 to 5% by mass of hydroxide. It contains a system compound and a remaining amount of water, and does not contain a corrosion inhibitor.
By including the compound represented by the chemical formula (1) without containing the corrosion inhibitor in the stripping solution composition, the stripping step can be effectively completed within a short time, and compared with other steps. In the stripping process performed at a high process temperature, composition change can be minimized, and the absence of corrosion inhibitors prevents post-process failures such as vapor deposition failure due to adsorption of water-insoluble corrosion inhibitors, and electrode damage To be able to prevent.
Generally, a corrosion inhibitor is a kind of surface protective agent that adheres to a metal surface and suppresses corrosion. In the corrosion inhibitor, polar groups are adsorbed on the metal surface, and the coating produced by the arrangement of the nonpolar groups changes the movement of charges, and prevents the movement of substances related to corrosion. Therefore, the compound represented by the chemical formula (1) used in the present invention is an amine component composed of a large number of N (nitrogen atoms), and maximizes the peeling performance depending on the degree of alkali. The metal surface can be protected by N groups to minimize metal electrode damage.

  Since the compound represented by the chemical formula (1) used in the present invention is water-soluble, it can prevent a post-process failure unlike other corrosion inhibitors. Examples thereof include ethylenediamine, diethylenetriamine, and triethylenetetra There are amine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine and the like, and these can be used alone or in combination of two or more. In particular, in the chemical formula (1), n is preferably an ethyleneamine series of 2 to 8. The compound in which n is 1 is ethylenediamine, and N (nitrogen atom) contained in the compound is insufficient to prevent corrosion, and when n is 9 or more, the molecular weight increases and the photoresist Since the ability to permeate decreases, the peeling performance is reduced.

  The content of the compound of the chemical formula (1) contained in the stripping solution according to the present invention is preferably 1 to 5% by mass based on the total mass of the composition. When it is less than 1% by mass, it is not effective for preventing corrosion, and when it exceeds 5% by mass, the content of the polar organic solvent is relatively reduced, and the peeling performance is lowered.

The polar organic solvent contained in the stripping composition according to the present invention can be used without limitation as long as it is a polar organic solvent used in the stripping composition. Specifically, for example,
Sulfoxides such as dimethylsulfoxide; Sulfones such as dimethylsulfone, diethylsulfone, bis (2-hydroxyethyl) sulfone, tetramethylenesulfone; N, N-dimethylformamide, N-methylformamide, N, N-dimethylacetamide, N
Amides such as methylacetamide and N, N-diethylacetamide; N, N′-dimethyllactamamide, 2-pyrrolidone, N-methyl-2-pyrrolidone (N-methylpyrrolidone), N-ethyl-2-pyrrolidone ( N-ethylpyrrolidone), N-propyl-2-pyrrolidone, N-hydroxymethyl-2-pyrrolidone, lactams such as N-hydroxyethyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone, 1, Imidazolidinones such as 3-diethyl-2-imidazolidinone and 1,3-diisopropyl-2-imidazolidinone; ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl Ether acetate And polyhydric alcohols such as ethylene glycol monoethyl ether acetate, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and derivatives thereof.

  These may be used alone or in combination of two or more. Among these, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methylformamide, N, N′-dimethyllactamamide, 1,3-dimethyl-2-amide It is more preferable to use one or more selected from the group consisting of imidazolidinone, diethylene glycol monomethyl ether, ethylene glycol monoethyl ether, N-methylpyrrolidone, N-ethylpyrrolidone, and 2-pyrrolidone because of excellent peelability.

  The content of the polar organic solvent contained in the stripping composition according to the present invention is preferably 70 to 95% by mass, more preferably 80 to 95% by mass. When the content is less than 70% by mass, there is a problem that the solubility in the photoresist is inferior, so there is a problem that the resist is not removed cleanly, and when the content exceeds 95% by mass, There is a problem in that the content of other components is insufficient, the peeling performance becomes poor, and a corrosion phenomenon may appear.

The hydroxide compound contained in the stripping solution according to the present invention is added in order to further improve the stripping performance of the negative photoresist, and tetraalkylammonium hydroxide is preferable. In this case, the alkyl can be selected from C ₁ -C ₅ alkyl groups.
The content of the hydroxide compound is preferably 0.1 to 5% by mass, more preferably 1 to 4% by mass with respect to the composition of the entire stripping solution. When the content is less than 0.1% by mass, there is a problem that the peeling performance is deteriorated, and when the content exceeds 5% by mass, the lower metal film may be corroded.

  The water contained in the composition of the present invention is not particularly limited, but deionized water can be used. Preferably, the deionized water has a specific resistance value of 18 MΩ / cm or more that shows the degree to which ions in the water are removed. Is used.

  Hereinafter, the present invention will be described in detail by way of examples. However, the following examples only illustrate the present invention, and the content of the present invention is not limited to the following examples.

<Examples 1-13 and Comparative Examples 1-7>
A negative photoresist stripping composition was prepared by blending the compound of formula (1), the polar organic solvent, the hydroxide compound, and water as shown in Table 1.

<Evaluation of photoresist stripping performance>
The photoresist stripping performance was evaluated for the photoresist stripping composition produced as shown in Table 1 above.
In order to evaluate the photoresist stripping performance of the above composition, a bump electrode made of a photoresist and a tin material was formed to a thickness of about 50 to 60 μm on a wafer plated with copper. Specifically, a photoresist film having a thickness of about 50 to 60 μm was formed on a wafer on which a UBM (Under Bump Metallurgy) layer was formed of copper. After forming a pattern in the exposure process performed in the above-described photoresist, a bump electrode made of a tin material was formed by electroplating through a development process.
Subsequently, the wafer comprised of the photoresist and the bump electrode was cut into a size of 3 cm × 3 cm to produce an evaluation specimen. The specimen was immersed in each stripping composition produced as shown in Table 1 for 3 minutes at 60 ° C. to remove the photoresist film. The specimen from which the photoresist film was removed was washed with ultrapure water for about 1 minute and then dried with nitrogen. The dried specimen was confirmed by FE-SEM to determine whether or not the photoresist could be removed (see FIGS. 1 and 2). FIG. 1 is an FE-SEM photograph of the bump electrode surface by the stripping solution composition evaluation of Example 1, and FIG. 2 is an FE-SEM photograph of the bump electrode surface by the stripping composition evaluation of Comparative Example 1 by stripping performance evaluation.
The above experimental conditions are intended to provide a simple condition and to observe with a large difference in the degree of peeling, compared to a normal bump electrode photoresist peeling process of 10 minutes or more. The results are shown in Table 2.
(Double-circle): A photoresist is removed 100% and there is no residue.
A: The photoresist is removed by 80% or more and there is almost no residue.
Δ: The photoresist is removed by 50% or more, and a considerable amount remains.
X: The photoresist is removed by less than 50%, and a slightly larger amount of photoresist remains.

<Metallic film corrosion evaluation>
The corrosiveness of the metal of the bump electrode was evaluated for the photoresist stripping composition produced as shown in Table 1 above.
In order to evaluate the metal corrosivity of the bump electrode of the above composition, a bump electrode made of a photoresist and a tin material was formed to a thickness of about 50 to 60 μm on a copper-plated wafer. Subsequently, the wafer comprised of the photoresist and the bump electrode was cut into a size of 3 × 3 cm to produce an evaluation specimen.
The specimen was immersed in each stripping composition produced as shown in Table 1 at 60 ° C. for 30 minutes, washed with ultrapure water for 1 minute, and dried using nitrogen. The degree of corrosion of the metal surface of the bump electrode was confirmed on the dried specimen by FE-SEM. FIG. 3 is a FE-SEM photograph of the bump electrode surface obtained by evaluating the corrosiveness of the metal film with the stripping solution composition of Comparative Example 1 not according to the present invention.
The above experimental conditions are intended to provide harsh corrosion conditions and to observe with a large difference in the degree of corrosion, compared to the ordinary bump electrode photoresist peeling process within 10 minutes. The results are shown in Table 2.
A: Corrosion of copper and tin is not observed.
○: Some metal corrosion of copper and tin is observed.
Δ: Partial metal corrosion of copper and tin is observed.
X: Overall metal corrosion of copper and tin is observed.

As can be seen from the above evaluation, the photoresist stripping solution composition according to the present invention does not contain a corrosion inhibitor and contains an appropriate amount of the compound represented by the chemical formula (1). It is possible to efficiently remove the thick photoresist and save cost by shortening the process time.

Claims (5)

Photoresist stripping containing 1 to 5% by mass of the compound represented by chemical formula (1), 70 to 95% by mass of a polar organic solvent, 0.1 to 5% by mass of a hydroxide compound, and the remaining amount of water. Liquid composition.
(In the formula, n is an integer of 2 to 8.)   The compound represented by the chemical formula (1) is selected from the group consisting of ethylenediamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, pentaethylenehexamine, hexaethyleneheptamine, and mixtures thereof. The photoresist stripping composition according to claim 1.   The polar organic solvent is dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methylformamide, N, N′-dimethyllactamamide, 1,3-dimethyl- The method according to claim 1, characterized in that it is selected from the group consisting of 2-imidazolidinone, diethylene glycol monomethyl ether, ethylene glycol monoethyl ether, N-methylpyrrolidone, N-ethylpyrrolidone, 2-pyrrolidone, and mixtures thereof. The photoresist stripping liquid composition as described. The photoresist stripping composition according to claim 1, wherein the hydroxide compound is a tetraalkylammonium hydroxide, wherein the alkyl is a C _{1 to} C ₅ alkyl. The photoresist stripping composition according to claim 1, wherein the photoresist stripping composition is used for removing a thick-film negative photoresist.