JP7786882B2 - Photoresist remover - Google Patents

Description

The present invention relates to a photoresist stripper.

Semiconductor substrates and the like have electrode structures with fine wiring, and photoresists are used in their manufacturing process. The electrode structures are manufactured, for example, by applying a photoresist to a conductive metal layer such as aluminum or an insulating film such as a _SiO2 film formed on a substrate, exposing and developing the photoresist to form a resist pattern, etching the conductive metal layer or insulating film using the patterned resist as a mask to form fine wiring, and then removing the unnecessary photoresist with a photoresist remover. In addition to photoresist stripping performance, the photoresist remover is required to have storage stability that prevents solidification and precipitation even at low temperatures.

Patent Document 1 discloses a photoresist stripper that contains quaternary ammonium hydroxide as a strong alkaline agent for stripping photoresist, an alkyleneamine for dissolving the quaternary ammonium hydroxide in dimethyl sulfoxide, and a polyhydric alcohol and/or a glycol ether with a molecular weight of 100 or less. While this stripper has improved storage stability at low temperatures, this is not sufficient, and further improvement in photoresist stripping performance is desired.

Patent Document 2 discloses that the photoresist stripping performance can be improved by blending multiple organic solvents into a photoresist stripper. However, this stripper does not have sufficient storage stability at low temperatures.

International Publication No. WO2017/065153 Japanese Patent Application Laid-Open No. 2007-254555

The objective of the present invention is to provide a photoresist stripper that has excellent storage stability while maintaining sufficient resist stripping properties.

The inventors discovered that a photoresist stripper containing a specific organic solvent has excellent storage stability while maintaining sufficient resist stripping properties, and thus completed the present invention.

That is, the present invention provides a photoresist stripping solution containing a quaternary ammonium hydroxide (A), water (B), and an organic solvent (C),
The organic solvent (C) is selected from the following organic solvents (C1), (C2), and (C3):
An organic solvent (C1) having a polarity parameter (dP) of the Hansen solubility parameter of 15.0 or more and less than 21.0, and a hydrogen bond parameter (dH) of 6.0 or more and less than 14.0.
An organic solvent (C2) having a polarity parameter (dP) of the Hansen solubility parameter of 3.0 or more and less than 14.0, and a hydrogen bond parameter (dH) of 8.0 or more and less than 31.0.
An organic solvent (C3) having a polarity parameter (dP) of the Hansen solubility parameter of 3.0 or more and less than 8.0, and a hydrogen bond parameter (dH) of 2.5 or more and less than 8.0.
The present invention relates to a photoresist stripper which is a mixture of

It is preferable that the content of organic solvent (C1) is 15 to 80% by weight.

It is preferable that the content of organic solvent (C2) is 1 to 50% by weight.

It is preferable that the content of organic solvent (C3) is 3 to 50% by weight.

It is preferable that the total content of organic solvents (C1) to (C3) is 60 to 95% by weight.

It is preferable that the photoresist stripper further contains an alkyleneamine or alkanolamine (D).

It is preferable that component (D) is an alkanolamine.

It is preferable that the organic solvent (C1) is dimethyl sulfoxide.

The photoresist stripper is preferably used to strip dry film resist.

The photoresist stripper of the present invention contains a mixture of specific organic solvents (C1) to (C3) in addition to quaternary ammonium hydroxide (A) and water (B), and therefore has excellent storage stability while maintaining sufficient resist stripping properties.

<<Photoresist remover>>
The photoresist stripping solution of the present invention is a photoresist stripping solution containing a quaternary ammonium hydroxide (A), water (B), and an organic solvent (C), wherein the organic solvent (C) is any of the following organic solvents (C1), (C2), and (C3):
(C1) An organic solvent having a polarity term (dP) of the Hansen solubility parameter of 15.0 or more and less than 21.0, and a hydrogen bonding term (dH) of 6.0 or more and less than 14.0; (C2) An organic solvent having a polarity term (dP) of the Hansen solubility parameter of 3.0 or more and less than 14.0, and a hydrogen bonding term (dH) of 8.0 or more and less than 31.0; (C3) A mixture of organic solvents having a polarity term (dP) of the Hansen solubility parameter of 3.0 or more and less than 8.0, and a hydrogen bonding term (dH) of 2.5 or more and less than 8.0.

<(A) Quaternary Ammonium Hydroxide>
As the quaternary ammonium hydroxide, for example, a compound represented by the following general formula (1) can be used.

In general formula (1), R ¹ to R ⁴ represent an alkyl group having 1 to 12 carbon atoms, a hydroxy-substituted alkyl group, or an aromatic-substituted alkyl group, and may be the same or different.

Specific examples of quaternary ammonium hydroxides include tetramethylammonium hydroxide (TMAH), trimethylethylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, trimethyl(2-hydroxyethyl)ammonium hydroxide, tripropyl(2-hydroxyethyl)ammonium hydroxide, and trimethyl(1-hydroxypropyl)ammonium hydroxide. These may be used alone or in combination of two or more. Of these, from the perspective of resist strippability, tetramethylammonium hydroxide, trimethylethylammonium hydroxide, tetrabutylammonium hydroxide, and benzyltrimethylammonium hydroxide are preferred. Furthermore, tetramethylammonium hydroxide is more preferred because it has the smallest molecular weight, a high molar concentration per unit weight, and works effectively.

In the photoresist stripper solution of the present invention, the content of quaternary ammonium hydroxide is not particularly limited, but is preferably 0.5 to 20% by weight, more preferably 0.8 to 8% by weight, and even more preferably 1 to 5%. If the content of quaternary ammonium hydroxide is less than 0.5% by weight, resist stripping properties may be reduced, and if it exceeds 20% by weight, metal corrosivity may increase.

<(B) Water>
Water is added to dissolve the quaternary ammonium hydroxide. The water content is not particularly limited, but from the viewpoint of resist strippability, it is preferably 30% by weight or less, and from the viewpoint of negative resist strippability, it is preferably 20% by weight or less. In particular, when the photoresist stripper of the present invention containing the alkyleneamine or alkanolamine (D) described below is used to strip a negative dry film resist, the water content is more preferably 10% by weight or less, even more preferably 1 to 10% by weight, and particularly preferably 2 to 6% by weight. If the water content is less than 1% by weight, the solubility of the quaternary ammonium hydroxide may decrease, and if it exceeds 10% by weight, the strippability of the negative dry film resist may decrease. On the other hand, when the photoresist stripper of the present invention not containing the alkyleneamine or alkanolamine (D) is used to strip a negative dry film resist, the water content is more preferably 2 to 15% by weight, even more preferably 4 to 10% by weight. If the water content is less than 2% by weight, the solubility of the quaternary ammonium hydroxide may decrease, and if it exceeds 15% by weight, the strippability of the negative dry film resist may decrease.

<(C) Organic Solvent>
Organic solvent (C) is a mixture of organic solvents (C1), (C2), and (C3). Organic solvents (C1) to (C3) are solvents that satisfy specific Hansen solubility parameters. The Hansen solubility parameters are Hildebrand solubility parameters expressed by three parameters: dispersion term dD, polarity term dP, and hydrogen bonding term dH. The dispersion term dD, polarity term dP, and hydrogen bonding term dH are material-specific physical property values and are shown, for example, in "Hansen Solubility Parameters: A User's Handbook, HSPiP 3rd Edition ver. 3.0.20." The hydrogen bonding term dH can be calculated using values described in the above literature or by using the Y-MB method, a neural network method.

The total content of organic solvents (C1) to (C3) in the entire photoresist stripper solution is not particularly limited, but from the perspective of balancing resist stripping properties and storage stability, it is preferably 60 to 95% by weight, more preferably 80 to 95% by weight, and even more preferably 85 to 95% by weight. If it is less than 60% by weight, the proportion of quaternary ammonium hydroxide and water will be high, which may cause metal corrosion, and if it exceeds 95% by weight, stripping properties may be insufficient.

<Organic Solvent (C1)>
The organic solvent (C1) has a polarity parameter (dP) of 15.0 or more and less than 21.0, and a hydrogen bond parameter (dH) of 6.0 or more and less than 14.0, in the Hansen solubility parameter. The polarity parameter (dP) is preferably 15.5 to 20, and more preferably 16 to 20. If the polarity parameter (dP) is less than 15.0, the release properties tend to be insufficient, and if it is 21.0 or more, the storage stability tends to be insufficient. The hydrogen bond parameter (dH) is preferably 6 to 13, and more preferably 7 to 12. If the hydrogen bond parameter (dH) is less than 6.0, the storage stability tends to be insufficient, and if it is 14.0 or more, the release properties tend to be insufficient.

The dispersion term (dD) of the Hansen solubility parameter of the organic solvent (C1) is not particularly limited, but is preferably 15 to 21, and more preferably 17 to 21. If it is less than 15 or exceeds 21, the peelability may be insufficient.

Specific examples of organic solvents (C1) include dimethyl sulfoxide, sulfolane, dimethyl sulfone, 2-pyrrolidone, and γ-butyrolactone. These solvents may be used alone or in combination.

The content of organic solvent (C1) in the entire photoresist stripping solution is not particularly limited, but is preferably 15 to 80% by weight, more preferably 50 to 80% by weight, and even more preferably 50 to 78% by weight. If it is less than 15% by weight or more than 80% by weight, the resist stripping properties may be insufficient.

<Organic Solvent (C2)>
The organic solvent (C2) has a polarity parameter (dP) of 3.0 or more and less than 14.0, and a hydrogen bond parameter (dH) of 8.0 or more and less than 31.0 in the Hansen solubility parameter. The polarity parameter (dP) is preferably 3.5 to 13, and more preferably 4 to 13. If the polarity parameter (dP) is less than 3.0, the release properties tend to be insufficient, and if it is 14.0 or more, the storage stability tends to be insufficient. The hydrogen bond parameter (dH) is preferably 8.5 to 30, and more preferably 9 to 30. If the hydrogen bond parameter (dH) is less than 8.0, the storage stability tends to be insufficient, and if it is 31.0 or more, the release properties tend to be insufficient.

The dispersion term (dD) of the Hansen solubility parameter of the organic solvent (C2) is not particularly limited, but is preferably 10 to 25, and more preferably 14 to 20. If it is less than 10, the peelability may be insufficient, and if it exceeds 25, the storage stability may be insufficient.

Specific examples of organic solvents (C2) include polyhydric alcohols such as glycerol; methoxybutanols such as 1-butoxy-2-propanol and 3-methoxy-3-methylbutanol; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol; ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, ethylene glycol hexyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol hexyl ether, and propylene glycol methyl ether. Examples of suitable solvents include glycol monoethers such as propylene glycol ethyl ether, propylene glycol butyl ether, propylene glycol hexyl ether, dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol butyl ether, dipropylene glycol hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol butyl ether, triethylene glycol hexyl ether, tripropylene glycol methyl ether, tripropylene glycol ethyl ether, tripropylene glycol butyl ether, and tripropylene glycol hexyl ether. These solvents may be used alone or in combination of two or more.

Among the above, polyhydric alcohols, methoxybutanols, and glycols are preferred as the organic solvent (C2), as they are effective even when added in small amounts.

The content of organic solvent (C2) in the entire photoresist stripping solution is not particularly limited, but is preferably 1 to 50% by weight, and more preferably 2 to 30% by weight. If it is less than 1% by weight, storage stability may be insufficient, and if it exceeds 50% by weight, resist stripping properties may be insufficient.

<Organic Solvent (C3)>
The organic solvent (C3) has a polarity term (dP) of the Hansen solubility parameter of 3.0 or more and less than 8.0, and a hydrogen bond term (dH) of 2.5 or more and less than 8.0. The polarity term (dP) is preferably 4.0 to 7.5, and more preferably 4.5 to 7.0. If the polarity term (dP) is less than 3.0, the release properties tend to be insufficient, and if it is 8.0 or more, the storage stability tends to be insufficient. The hydrogen bond term (dH) is preferably 3 to 7.5, and more preferably 4.0 to 7.0. If the hydrogen bond term (dH) is less than 2.5, the release properties tend to be insufficient, and if it is 8.0 or more, the storage stability tends to be insufficient.

The dispersion term (dD) of the Hansen solubility parameter of the organic solvent (C3) is not particularly limited, but is preferably 10 to 20, and more preferably 13 to 18. If it is less than 10, storage stability may be insufficient, and if it exceeds 20, storage stability may be insufficient.

Specific examples of organic solvents (C3) include ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether, dipropylene glycol diethyl ether, dipropylene glycol dibutyl ether, ethylene glycol methyl ethyl ether, ethylene glycol methyl butyl ether, and ethylene glycol methyl ether. Examples of the solvent include glycol diethers such as diethylene glycol methyl ether, diethylene glycol methyl butyl ether, diethylene glycol methyl ether, triethylene glycol methyl ether, triethylene glycol methyl butyl ether, triethylene glycol methyl butyl ether, propylene glycol methyl ether, propylene glycol methyl butyl ether, propylene glycol methyl butyl ether, dipropylene glycol methyl ether, dipropylene glycol methyl butyl ether, dipropylene glycol methyl butyl ether, tripropylene glycol methyl ether, tripropylene glycol methyl butyl ether, and tripropylene glycol methyl butyl ether. These solvents may be used alone or in combination of two or more.

Among the above, dimethyl ethers are preferred as the organic solvent (C3) because of their good stripping properties.

The content of organic solvent (C3) in the entire photoresist stripper solution is not particularly limited, but is preferably 3 to 50% by weight, and more preferably 5 to 40% by weight. If it is less than 3% by weight, storage stability may be insufficient, and if it exceeds 50% by weight, stripping properties may be insufficient.

<Optional ingredients>
The photoresist stripper solution of the present invention may contain other optional components in addition to the aforementioned components (A) to (C), such as alkyleneamine or alkanolamine (D), anticorrosive agents, organic solvents other than component (C), surfactants, and antifoaming agents.

When the photoresist remover contains an alkyleneamine or alkanolamine (D), the alkyleneamine or alkanolamine (D) acts as a dissolving agent for the quaternary ammonium hydroxide.

The alkyleneamine is not particularly limited, and a compound represented by the following general formula (2) can be used.

(In general formula (2), m and n represent integers of 1 to 5. ^{R 5} and R ⁶ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. When there are multiple R ^5s and multiple R ^6s , they may be the same or different.)

Specific examples of alkyleneamines include ethyleneamines represented by the following general formula (3), such as ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), and pentaethylenehexamine (PEHA), as well as propylenediamine. Among these, from the viewpoint of carbon dioxide absorbency, ethyleneamines represented by the following general formula (3) are preferred, polyethyleneamines with n=2 or more are more preferred, and triethylenetetramine and tetraethylenepentamine are even more preferred. These alkyleneamines may be used alone or in combination of two or more.
(In general formula (3), n represents an integer of 1 to 5.)

Specific examples of alkanolamines include monoethanolamine (MEA), N-methylethanolamine (MMA), monomethyldiethanolamine (MDA), and triethanolamine (TEA). Of these, monoethanolamine is preferred from the standpoint of storage stability.

When alkyleneamine or alkanolamine (D) is added to the photoresist stripper solution of the present invention, its content is not particularly limited, but is preferably 0.5 to 25% by weight, and more preferably 1 to 20% by weight. If the alkyleneamine or alkanolamine (D) content is less than 0.5% by weight, stability over time may decrease, and if it exceeds 25% by weight, resist stripping properties may decrease. Furthermore, from the perspective of stability over time, the content of alkyleneamine or alkanolamine (D) is preferably 10 parts by weight or more per 100 parts by weight of quaternary ammonium hydroxide.

The corrosion inhibitor is not particularly limited, but examples include nitrogen-containing heterocyclic compounds such as benzotriazole, aminotetrazole, 5-amino-1-phenyltetrazole, 5-amino-1-(1-naphthyl)tetrazole, 1-methyl-5-aminotetrazole, 1,5-diaminotetrazole, imidazole, indole, purine, pyrazole, pyridine, pyrimidine, pyrrole, pyrrolidine, and pyrroline, as well as maltol and creatinine. These may be used alone or in combination, but from the perspective of corrosion prevention against multiple metals, it is desirable to contain maltol and creatinine. From the perspective of corrosion prevention against Cu, it is desirable to contain benzotriazole, indole, and pyrroline. The content of the corrosion inhibitor is preferably 0.01 to 5 wt.%.

Organic solvents other than component (C) include ethylene carbonate, propylene carbonate, N-methylpyrrolidone, etc. The content of these organic solvents is preferably 1 to 10% by weight.

Examples of surfactants include cationic surfactants such as distearyldimethylammonium chloride, anionic surfactants such as alkylbenzenesulfonates, amphoteric surfactants such as cocamidopropyl betaine, and nonionic surfactants such as polyoxyethylene alkyl ethers. The surfactant content is preferably 0.01 to 1% by weight.

Antifoaming agents include silicone oil and fatty acid esters. The content of antifoaming agent is preferably 0.01 to 1% by weight.

The photoresist stripper solution of the present invention can be prepared by mixing the above-mentioned components using conventional methods. After preparation, it can be stored at temperatures between -5 and 40°C without becoming cloudy, coagulating, or precipitating.

The photoresist stripper of the present invention can be used to strip unnecessary photoresist after etching of metal wiring, etc., in the manufacturing process of semiconductor substrates, flat panel display (FPD) substrates, etc. The photoresist stripper of the present invention can be used at room temperature or heated to, for example, 30°C to 80°C. The time required for stripping depends on the degree of deterioration of the photoresist, but is generally, for example, about 30 seconds to 10 minutes. After treatment, water rinsing, air blow drying, etc. can be performed as necessary.

To remove photoresist from a metal wiring substrate having a copper layer or copper alloy layer using the photoresist remover of the present invention, when forming metal wiring having a copper layer or copper alloy layer on the substrate using photoresist, the photoresist remover of the present invention is used to remove the unnecessary photoresist to prevent corrosion of the copper layer or copper alloy layer. More specifically, the substrate is immersed in the photoresist remover of the present invention at, for example, room temperature to 80°C for 1 to 30 minutes. At this time, the photoresist remover may be stirred or the substrate may be vibrated, if necessary. Alternatively, the photoresist remover of the present invention may be sprayed onto the substrate using a shower or spray. In this case, brush cleaning may also be used in combination to improve resist removal properties.

After dissolving or stripping the photoresist, the photoresist remover containing the dissolved resist is washed away, preferably with pure water, to remove the resist from the substrate. The liquid on the substrate is then blown off with an air knife or the like, and the substrate is dried. This prevents excessive corrosion of the copper layer or copper alloy layer, which would otherwise result in a reduction in the line width of the copper or copper alloy wiring. This allows for the formation of high-quality metal wiring without compromising the cross-sectional shape of the wiring formed by etching. Examples of multilayer metal wiring include, from top to bottom, a single-layer wiring of copper or copper alloy; a two-layer wiring of copper or copper alloy/copper or copper alloy with a different composition from the top layer; a two-layer wiring of copper or copper alloy/cap metal such as molybdenum or titanium; and a three-layer wiring of a cap metal such as molybdenum or titanium/copper or copper alloy/cap metal such as molybdenum or titanium.

The photoresist stripper of the present invention can be used to strip both positive and negative photoresists, but due to its high photoresist stripping properties, it is particularly suitable for stripping negative dry film resists.

The present invention will be explained below using examples, but the present invention is not limited to these examples.

The Hansen solubility parameters of the organic solvents used in the examples are shown in Table 1.

(Examples 1 to 12, Comparative Examples 1 to 5)
Components (A) to (D) were mixed in the weight ratios shown in Table 2 below to obtain a photoresist stripper. The liquid state and resist stripping ability of the obtained photoresist stripper were evaluated using the methods described below. The results are shown in Table 2.

(Evaluation method)
1. Liquid State The liquid state of the photoresist stripper solution was visually observed at −5° C., 0° C. and 24° C. and evaluated according to the following criteria.
◎: No turbidity ○: Slight turbidity △: Turbidity ×: Coagulation XX: Precipitation

2. Resist-removable: A Ti film and a copper seed layer were each formed by sputtering on a Si substrate, and then a photoresist (negative dry film resist: Sunfort "TS-B400" manufactured by Asahi Kasei Corporation) was roll-laminated to a thickness of 240 μm. The photoresist was patterned by UV exposure and development, and then a copper plating layer (thickness 200 μm) was formed by electroplating. This substrate was immersed in a photoresist stripper adjusted to 70°C and treated for 30 minutes. After immersion, the substrate was washed with water and air-dried. The degree of dry film resist removal was confirmed using an electron microscope and evaluated according to the following criteria.
◎: No dry film resist is present on the substrate and is completely dissolved in the stripping solution. ○: No dry film resist is present on the substrate, but a small amount of residue remains in the stripping solution. △: A thin residue remains on the substrate. Residue remains in the stripping solution. ×: A thick residue remains on the substrate. Residue remains in the stripping solution. XX: The dry film resist is barely dissolved and is almost unchanged from before the stripping process.

Comparative Example 1 did not contain organic solvent (C3), and therefore had poor resist stripping properties. Comparative Example 2 did not contain organic solvent (C2), and therefore had a high freezing point, causing quaternary ammonium hydroxide to precipitate at low temperatures, resulting in poor liquid state and resist stripping properties. Comparative Example 3 did not contain organic solvent (C1), and therefore had poor resist stripping properties. Comparative Examples 4 and 5 did not contain organic solvent (C3), and therefore had poor resist stripping properties, and also had a high freezing point and solidified at low temperatures. Examples 1 to 12 maintained a stable liquid state even at low temperatures, and also had good resist stripping properties.

Claims (9)

A photoresist stripping solution comprising a quaternary ammonium hydroxide (A), water (B), an organic solvent (C) , and an alkyleneamine or alkanolamine (D) ,
The organic solvent (C) is selected from the following organic solvents (C1), (C2), and (C3):
Organic solvent (C1) which is dimethyl sulfoxide
An organic solvent (C2) having a polarity parameter (dP) of the Hansen solubility parameter of 3.0 or more and less than 14.0, and a hydrogen bond parameter (dH) of 8.0 or more and less than 31.0.
An organic solvent (C3) having a polarity parameter (dP) of 3.0 or more and less than 8.0, a hydrogen bond parameter (dH) of 2.5 or more and less than 8.0 , and being a dimethyl ether .
is a mixture of
The content of the quaternary ammonium hydroxide (A) is 5% by weight or less,
the content of the organic solvent (C1) is 50 to 80% by weight,
the content of the organic solvent (C2) is 1 to 50% by weight,
The content of the organic solvent (C3) is 3 to 50% by weight.
A photoresist remover for removing photoresist from metal wiring boards . 2. The photoresist stripping solution according to claim 1, wherein the content of the organic solvent (C1) is 50 to 78 % by weight. 3. The photoresist stripping solution according to claim 1, wherein the content of the organic solvent (C2) is 2 to 30 % by weight. 4. The photoresist stripping solution according to claim 1, wherein the content of the organic solvent (C3) is 5 to 40 % by weight. The photoresist stripper according to any one of claims 1 to 4, wherein the total content of organic solvents (C1) to (C3) is 60 to 95% by weight. 6. The photoresist stripping solution according to claim 1 , wherein the content of the alkyleneamine or alkanolamine (D) is 0.5 to 25% by weight. 7. The photoresist stripping solution according to claim 1, wherein the component (D) is an alkanolamine. 8. The photoresist stripping solution according to claim 1, wherein the organic solvent (C3) is triethylene glycol dimethyl ether. A photoresist stripper according to any one of claims 1 to 8, for use in stripping dry film resist.