WO2014208088A1 - Remover liquid for photoresists - Google Patents

Abstract

Provided is a remover liquid for photoresist films, which removes a photoresist film without damaging a Cu film, and which does not decrease adhesion between the Cu film and a layer deposited thereon, said photoresist film having been changed in the properties and having become difficult to remove by being exposed to an etchant for Cu films during wet etching of the Cu film or Cu alloy film on a large-area substrate for the formation of wiring lines or the like. A remover liquid for photoresists, which is characterized by containing 40-60% by mass of water, 1-15% by mass of a tertiary alkanolamine and 25-59% by mass of a polar solvent, or alternatively, by containing more than 60% by mass but 80% by mass or less of water, 1-8% by mass of a tertiary alkanolamine and 12-39% by mass of a polar solvent.

Description

Stripper for photoresist

The present invention relates to a photoresist stripping solution. In particular, the present invention relates to a resist stripping solution suitably used for manufacturing Cu or Cu alloy wiring boards for flat panel displays (FPD) such as liquid crystal displays and organic EL displays.

In ICs, LSIs, etc., with the high integration of semiconductor elements and the reduction in chip size, the miniaturization and multilayering of wiring circuits have progressed, resulting from the resistance (wiring resistance) and wiring capacitance of metal films used in semiconductor elements. Signal delay is considered a problem. For this reason, copper (Cu) having a resistance lower than that of aluminum (Al) is used to reduce the wiring resistance.

On the other hand, Al has been used as a conventional wiring material in FPDs such as liquid crystal displays, but it is necessary to lower the wiring resistance in the same way as semiconductor elements in order to cope with the recent increase in substrate size, higher definition, and organic EL. There is an attempt to use Cu or Cu alloy having a lower resistance than Al as a wiring material.

Cu is less susceptible to corrosion in an aqueous solution because it has less protective oxide film formed on the surface than Al. Therefore, there is a problem that the wiring pattern cannot be stably formed. Therefore, in the manufacture of semiconductors, corrosion is prevented by a dry process using plasma. However, the FPD has a larger substrate size than a semiconductor, and it is difficult to apply a dry process using plasma. Therefore, development of wiring formation using a wet etching method is indispensable.

The problem when Cu is used as the wiring material is the corrosion of the Cu film surface by wet etching as described above. As is well known, in photolithography by wet etching, a wiring pattern is formed with a resist on a Cu film formed on a substrate, an unnecessary portion of the Cu film is removed by an etchant that dissolves Cu, and finally, A desired wiring pattern can be obtained by removing the resist film.

Here, the Cu film is corroded in the final resist film peeling step. In this step, since the resist film adhering to the Cu film surface disappears, the Cu film surface is directly exposed to the stripping solution. In particular, the resist film stripping solution exhibits alkalinity and also contains water. Therefore, the Cu film is easily corroded. In view of this, development of a stripping solution for a photoresist that achieves a good balance between stripping the photoresist film and preventing corrosion of the Cu film has been performed.
The main technique is to mix a Cu film corrosion inhibitor into the stripping solution.

In Patent Document 1, (a) 10 to 65% by weight of a nitrogen-containing organic hydroxy compound, (b) 10 to 60% by weight of a water-soluble organic solvent, (c) 5 to 50% by weight of water, (d ) A photoresist stripping solution containing 0.1 to 10% by weight of a benzotriazole-based compound is disclosed, and (a) the nitrogen-containing organic hydroxy compound has an acid dissociation constant (pKa) in an aqueous solution at 25 ° C. of 7. 5-13 amines are preferred.

However, with such a composition, the pH of the photoresist stripping solution becomes a strong alkali of 10 or more. Therefore, the copper wiring is easily dissolved, that is, corroded by generating HCuO 2− and CuO 2− ions by dissolved oxygen in the liquid. Further, the anticorrosive agent (d) benzotriazole-based compound cannot form a polymer film having a high degree of polymerization in a strong alkaline solution and has a low anticorrosion property. Therefore, the addition amount must be increased, and the excessively added benzotriazole-based compound may remain on the Cu film wiring and may remain as a foreign substance.

In Patent Document 2, (a) primary or secondary alkanolamine is 5 to 45% by weight, (b) polar organic solvent and water are 50 to 94.95% by weight, and (c) maltol, uracil, 4-hydroxy- A photoresist stripping solution comprising 0.05 to 10% by weight of at least one heterocyclic compound selected from the group consisting of 6-methyl-2-pyrone and the like has been proposed. Even in such a composition, the pH of the photoresist stripping solution is a strong alkali of 10 or more, and the copper wiring is easily corroded. Therefore, if the anticorrosive agent (c) is added excessively, the anticorrosive agent (c) may remain on the Cu wiring and may remain as foreign matter.

Patent Document 3 discloses a method of manufacturing a semiconductor device in which a copper wiring pattern is formed on a substrate and then the copper wiring pattern is cleaned using an aqueous solution containing 2 × 10 −6 to 10−1 mol · dm−2 of benzotriazole. Proposed.

Furthermore, in the wet etching method, various solutions including stripper are used in large quantities. If these are discarded as they are, there is a high risk of environmental pollution. It is also a relatively expensive material. Therefore, it is preferable that the stripping solution used can be used repeatedly while being recycled after being recycled.

From this point of view, Patent Document 4 discloses a stripping solution comprising a polyhydric alcohol, an alkanolamine, water, a glycol ether, and an anticorrosive. In particular, water is 30% by mass or less from the viewpoint of recycling, and glycol ether is desirably 60% by mass or more as a main recycling material.

Although these disclosed techniques are considered in terms of damage to the Cu film when the resist film is peeled off, adhesiveness when forming another film on the Cu film has not been considered. . Therefore, when a Cu or Cu alloy layer on a large-area substrate is wet-etched to form a wiring or the like, the photoresist film that has been exposed, altered, and difficult to peel off is peeled off so as not to damage the Cu film. In addition, it is a stripping solution for a photoresist film that does not lower the adhesive force between the film formed on the Cu film, and the resist film can be stripped, the Cu film can be corroded, and the Cu film can be repeatedly recycled. In addition, a photoresist stripping solution that can maintain the adhesion to the formed film on the Cu film has been desired.

On the other hand, Patent Document 5 is a photo characterized in that the tertiary alkanolamine is 1 to 9% by mass, the polar solvent is 10 to 70% by mass, the water is 10 to 40% by mass, and the resist component is 3000 ppm. A resist stripping solution is proposed.

This photoresist stripping solution uses a photosensitive resist component as a corrosion inhibitor for Cu film. Since the resist component has a higher boiling point than solution components such as tertiary alkanolamine, polar solvent, and water, it can be completely separated. Therefore, no matter how many times the drainage of the stripping solution is regenerated, the resist component does not remain in the regenerated solution, and the corrosion inhibitor is not concentrated.

Japanese Patent No. 3514435 JP 2008-216296 A Japanese Patent No. 3306598 JP 2007-114519 A JP 2012-242696 A

In Patent Document 1, Cu etching is evaluated by performing a dry etching process. It is known that the etchant of Cu and the etchant of Al are different. In particular, in the case of an oxidant-based etchant that wet-etches Cu, the resist film is altered and is difficult to peel off. That is, the photoresist film stripping solution disclosed in Patent Document 1 cannot be simply applied as a photoresist film stripping solution used in the step of wet etching treatment of Cu or Cu alloy.

Patent Document 2 considers this point, and exactly discloses a stripping solution for a photoresist film used when wet etching Cu or Cu alloy on a large-area substrate. However, since the primary or secondary alkanolamine used as the main component of the stripping solution shows strong alkali, the action of the heterocyclic compound added as a corrosion inhibitor is weakened. Therefore, the heterocyclic compound has a considerably large composition of 0.05 to 10 wt%.

Patent Document 2 does not consider that these heterocyclic compounds added as a corrosion inhibitor form an insoluble compound with the Cu film to prevent corrosion. It is the point which reduces the adhesiveness between the layers processed into a film. That is, the corrosion inhibitor in an amount of 0.05 to 10 wt% causes a problem that the adhesion with the film formed on the Cu film is lowered.

In Patent Document 3, BTA (benzotriazole) is used as a Cu film to prevent corrosion when the Cu film is brought into contact with a cleaning agent in the cleaning process when the photoresist film on the Cu film is peeled off. It discloses the formation of insoluble compounds in between. However, the Cu film is basically a process in dry etching. Further, like Patent Document 2, the adhesiveness to the next layer formed on the Cu film is not taken into consideration.

Furthermore, the following problems arise from the viewpoint of recycling the stripping solution. Among the materials constituting the stripping solution, the amine-based material, the solvent, and the corrosion inhibitor have close boiling points and are not easily separated. That is, the amine material, the solvent, and the corrosion inhibitor are separated together. The separated separation liquid is regenerated by adding the shortage by inspecting the composition ratio of the materials.

Here, considering the adhesiveness with the film formed on the Cu film as described above, only a trace amount of the corrosion inhibitor can be added. If it does so, it will become difficult to test | inspect the content of the corrosion inhibitor in the liquid isolate | separated from the effluent of stripping liquid by distillation etc. This is because the content is small and the boiling point is close to that of amine-based materials and solvents, so that discrimination and discrimination are not possible.

When the recycling (recycling) process is repeated in such a situation, the corrosion inhibitor is concentrated in the stripping solution although the content is very small. The corrosion inhibitor exhibits a corrosion prevention effect in a small amount. That is, a non-moving body is formed on the Cu film. Therefore, even if it is concentrated even a little, the adhesiveness of the film formed on the Cu film is surely affected. As a result, when the stripping solution is recycled, a problem such as pinholes or stripping from the Cu film occurs suddenly on the film formed on the Cu film.

In addition, in the photoresist stripping solution of Patent Document 5, which is said to have improved these points, when the resist stripping solution is circulated and used in the resist stripping step, the stripped resist film dissolves in the photoresist stripping solution, and the resist Increased component concentration. When the resist component concentration increases, the resist film is peeled off, but an organic layer that is too thin to be observed by SEM remains on the outermost surface of Cu, and there is a problem that film peeling occurs when film formation is performed after the peeling process. there were.

The present invention is for a photoresist that can maintain good cleanliness of the outermost surface of Cu even when the concentration of the resist component in the photoresist stripping solution increases while the same stripping solution for photoresist is circulated. Provide stripping solution.

In order to solve the above problem, the stripping solution for photoresist of the present invention comprises:
40-60 mass% water,
1 to 15% by weight of a tertiary alkanolamine,
It has a polar solvent of 25 to 59% by mass.

Moreover, the stripping solution for photoresist of the present invention comprises:
More than 60% by weight and less than 80% by weight water,
1 to 8% by weight of a tertiary alkanolamine,
It may have 12 to 39% by mass of a polar solvent. Furthermore, in any case, the resist component may contain a trace amount (δ).

In the photoresist stripping solution,
The polar solvent is composed of propylene glycol (PG) and diethylene glycol monobutyl ether (BDG), and the ratio of the diethylene glycol monobutyl ether to the polar solvent is 5/8 or more.

In the photoresist stripping solution,
The tertiary alkanolamine is N-methyldiethanolamine (MDEA).

In the photoresist stripping solution, the resist component is a component from an exposed positive photoresist.

In the present invention, the water content is increased from 40 to 80, compared to the case of Patent Document 5. By doing in this way, it can prevent that the organic substance layer of Cu film surface adheres, ensuring the peelability of a resist film. As a result, the outermost surface of the Cu film can be kept clean, and there is an effect that the problem of film peeling between the film laminated on the Cu film does not occur.

In the present invention, the resist component is used as a corrosion inhibitor for Cu films. The resist component has a boiling point higher than that of a solution component such as a tertiary alkanolamine, a polar solvent, and water, and thus can be completely separated. Therefore, no matter how many times the drainage of the stripping solution is regenerated, the resist component does not remain in the regenerated solution, and there is no fear that the corrosion inhibitor is concentrated.

Also, it can be said that the corrosion inhibitor and the resist film dissolution aid are present on the resist film side. Therefore, a remanufactured photoresist stripping solution can be prepared by controlling the proportions of tertiary alkanolamine, a polar solvent, and water without a trace additive. Therefore, it is easy to manage the reclaimed photoresist stripping solution.

It is the graph which investigated the relationship between the moisture content in a resist peeling liquid, and the contact angle on Cu film after a resist film was peeled. It is a graph which shows the relationship between a moisture content and an etching rate.

Hereinafter, the stripping solution for photoresist according to the present invention will be described. The following description shows one embodiment of the photoresist stripping solution according to the present invention, and the following embodiments and examples may be modified without departing from the gist of the present invention. The photoresist stripping solution according to the present invention refers to a stripping solution for photoresist. A film formed of a photoresist is also called a photoresist film or a resist film.

The photoresist stripper of the present invention has 40 to 60% by mass of water, 1 to 15% by mass of a tertiary alkanolamine, and 25 to 59% by mass of a polar solvent. Further, it may have water of more than 60% by mass and 80% by mass or less, 1 to 8% by mass of tertiary alkanolamine, and 12 to 39% by mass of polar solvent.

Specific examples of tertiary alkanolamines that can be suitably used include the following. Triethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, N, N-dibutylethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N-methyldiethanolamine Etc. These may be used in combination of a plurality of types.

The polar solvent may be an organic solvent having an affinity for water. Moreover, it is more suitable if the mixing property with said tertiary alkanolamine is favorable.

Examples of such water-soluble organic solvents include sulfoxides such as dimethyl sulfoxide; sulfones such as dimethyl sulfone, diethyl sulfone, bis (2-hydroxyethyl) sulfone, and tetramethylene sulfone; N, N-dimethylformamide, N-methyl Amides such as formamide, N, N-dimethylacetamide, N-methylacetamide, N, N-diethylacetamide; N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N -Lactams such as hydroxymethyl-2-pyrrolidone and N-hydroxyethyl-2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-diisopropyl -2-Imidazolidinones such as imidazolidinone; Glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol mono Examples thereof include polyhydric alcohols such as diethylene glycol monoalkyl ether such as butyl ether (alkyl is a lower alkyl group having 1 to 6 carbon atoms), and derivatives thereof. Among these, at least one selected from dimethyl sulfoxide, N-methyl-2-pyrrolidone, and diethylene glycol monobutyl ether is preferably used from the viewpoints of further peelability and anticorrosiveness to the substrate. Of these, diethylene glycol monobutyl ether and N-methyl-2-pyrrolidone are particularly preferred. These components may be used in combination of a plurality of types.

It is also preferable to use propylene glycol (PG) and diethylene glycol monobutyl ether (BDG) in a ratio of 3: 5. In particular, diethylene glycol monobutyl ether is preferably mixed at a ratio of 5/8 or more of the polar solvent. This is because diethylene glycol monobutyl ether dissolves resist components well.

Note that the mixing ratio of PG and BDG may be adjusted depending on the properties of the resist film to be peeled off. For example, when a-Si (amorphous silicon) of a semiconductor layer is dry-etched, the resist film is exposed to severe conditions such as high temperature and radical atmosphere caused by plasma. As a result, the resist film is denatured, and even when immersed in a resist stripping solution having a polar solvent having a ratio of PG to BDG of 3: 5, it may be difficult to remove the resist film. In such a case, a large amount of BDG having an excellent function of dissolving the resist film may be blended.

However, since BDG lowers the pH when mixed with water, if the ratio is too large, the pH of the resist stripping solution is lowered (to the acidic side). That is, when the ratio of BDG is increased, the effect of amine (MDEA) that the pH of the resist stripping solution is set to the alkali side may be offset. This leads to a reduction in the effect of the resist stripping solution.

On the other hand, PG mainly has a function of swelling the resist film. Therefore, in order to make it easy to peel off the resist film, it is preferable that it be present even in a small amount. In addition, since PG maintains neutrality even if it mixes with water, regarding the pH, the amount of use is high.

Therefore, it is desirable that the mixing ratio of PG and BDG is 3: 5 in a usage situation where the resist film is not very modified like wet etching. However, when the resist film is modified as described above, the ratio of BDG may be changed to 5/8 or more.

The water is preferably pure water, but may contain impurities within the industrially usable range. That is, it is not necessary to use pure water that has passed through the RO membrane. This is because some impurities may be tolerated when a wiring of several μm or more is formed.

Water is preferably contained in an amount of 40 to 80% by mass, preferably 40 to 60% by mass, based on the entire resist stripping solution. When the amount of water is less than 40% by mass, an organic layer remains on the Cu surface, and there is a high possibility that “film peeling” occurs in which the film deposited on the Cu film is peeled off. On the other hand, if it exceeds 80% by mass, the photoresist film will not peel off.

In the present invention, in addition to the solution components (tertiary alkanolamine, polar solvent and water), a resist component may be contained at 1 ppm or more and 3000 ppm or less. The resist component is a component of the photoresist film from which the stripping solution of the present invention is stripped. More specifically, it is a resist component that is exposed, exposed to an etchant (acidic), and peeled off from the Cu film surface by a stripping solution in a photolithography process.

Therefore, in the present invention, the “resist component” may be a component in which the component of the photoresist film before exposure is changed. In other words, even a component that is not contained in the photoresist film before being exposed, is a component that is contained in the exposed photoresist film or is dissolved in the solution component from the exposed photoresist film, or a stripping solution Any component that has been changed and melted by associating with the sorbent may be used. Here, “exposure” includes not only exposure performed by a light source such as a halogen lamp but also exposure to light under a light source such as a fluorescent lamp or LED.

When the inventor of the present invention dissolves a photoresist film coated and exposed on a Cu film with solution components (tertiary alkanolamine, polar solvent and water), the corrosion of the Cu film is not substantially problematic. It was confirmed that the solubility of the resist film can be maintained.
The reason for this is not clear, but is considered as one explanation as follows.

A positive photoresist is a mixture of a resin that dissolves in an alkaline solution and a photosensitive agent, and it is considered that the photosensitive agent protects the melting point of the resin. As the resin, novolic resin is often used. In the case of a positive photoresist, diazonaphthoquinone (DNQ) is often used as the photosensitive agent. This DNQ changes to indenketene when exposed to light.
When indenketene encounters water, it undergoes a hydrolysis reaction and changes to indenecarboxylic acid.

イ ン Indenecarboxylic acid dissolves in an alkaline solution. As a result, the melting point of the resin is exposed to the alkaline solution, and the photoresist film is peeled off. Here, it is considered that this indenecarboxylic acid adheres to the surface of the Cu film, thereby preventing corrosion of the Cu film from solution components (tertiary alkanolamine, polar solvent and water). Moreover, since this indenecarboxylic acid has a melting point of 200 ° C. or higher, separation from the solution component of the stripping solution is extremely easy. Therefore, the resist component is preferably a component from a positive photoresist.

In the stripping solution of the present invention, it is considered that the resist component is responsible for preventing corrosion of the Cu film surface. Therefore, the stripping solution that is used for the first time is supplied from the exposed photoresist film on the Cu film even if it does not contain a resist component. However, this also means that the concentration of the resist component in the stripping solution increases with repeated use. Since the resist component includes a resin constituting the resist film, an increase in the concentration of the resist component also leads to an increase in debris (resist film fragments). Further, when a large amount of resist component remains on the surface of the Cu film, the adhesiveness with the film formed on the Cu film is lowered.

That is, there is an upper limit to the concentration of the resist component for effectively using the stripping solution. In the stripping solution of the present invention, the resist component in the stripping solution to be repeatedly used is preferably 3000 ppm or less in the stripping solution. This is because, when the resist component exceeds this concentration, a defective portion such as a pinhole occurs in the film formed on the Cu film. In other words, the stripping solution of the present invention can be used repeatedly without being regenerated until the concentration of the resist component is increased to 3000 ppm.

In the resist stripping solution according to the present invention, since the content of the resist component is very small, it is simply expressed as δ when showing the content. That is, δ means 1 ppm or more and 3000 ppm or less with respect to the total amount of the resist stripping solution. Therefore, in the description of the composition ratio, only tertiary alkanolamine, polar solvent and water may be added to reach 100% by mass.

Also, resist components that cannot be cleaned remain in the stripping tank or stripping process in which the resist stripping solution is regularly used. Therefore, in the case of additional replenishment or the like, the resist stripping solution may be composed of only the tertiary alkanolamine, the polar solvent, and water.

Since the resist stripping solution of the present invention is considered to have obtained a corrosion inhibitor from the resist component, corrosion of the Cu film surface is suppressed. However, if the corrosion force of other components in the stripping solution is so strong that it cannot be protected by a corrosion inhibitor, the surface of the Cu film is corroded. Therefore, the ratio of the tertiary alkanolamine, the polar solvent and the water in the stripping solution of the present invention is alkaline enough to dissolve the exposed resist film, and the Cu film is substantially in the presence of the resist component. It is necessary to have a corrosive force that remains. Here, the fact that the Cu film substantially remains means that the Cu film remains to the extent that it does not hinder the product even if the exposed resist film on the Cu film is removed by the stripping solution.

Therefore, the blending amount of the tertiary alkanolamine in the photoresist stripping solution of the present invention is preferably 1 to 8% by weight with respect to the total amount of the resist stripping solution in the range of 40 to 80% by weight of water.
More preferably, the amount of water may be increased to 1 to 15% by mass relative to the total amount of the resist stripping solution in the range of 40 to 60% by mass. If the tertiary alkanolamine is contained in an amount of more than 15% by mass with respect to the total amount of the resist stripping solution, the Cu film will be corroded even if the resist component is contained. If it is less than 1% by mass, the photoresist film cannot be peeled off.

The ratio of polar solvent can be determined as the balance of water and tertiary alkanolamine.
More specifically, when water is 40 to 60% by mass and tertiary alkanolamine is 1 to 15% by mass, the composition ratio of the polar solvent is 25 to 59% by mass. When water is more than 60% by mass and 80% by mass or less and tertiary alkanolamine is 1 to 8% by mass, the composition ratio of the polar solvent is 12 to 39% by mass.

Also, the temperature of the reaction between the resin or photosensitizer in the photoresist and the stripping solution is very important. Therefore, temperature control when using the stripping solution is strictly performed. The stripping solution and the object to be treated of the present invention are preferably in the range of 35 ° C to 45 ° C, and more preferably in the range of 38 ° C to 42 ° C. Further, it is desirable that the object to be treated and the stripping solution are treated at the same temperature. Since the base material of FPD is very large, the space where the stripping solution is used becomes a large space. This is because the temperature range from 35 ° C. to 45 ° C. allows such a space to stably carry out a chemical reaction and maintain large temperatures without requiring large energy.

Examples of the present invention are shown below together with comparative examples, but the present invention is not limited to the following examples. First, sample preparation and evaluation methods will be described.

<Production Method of Evaluation Substrate> In order to show the effect of the photoresist stripping solution of the present invention, an evaluation substrate was produced by the following procedure. First, ITO (Indium Tin Oxide: transparent electrode) was formed on a glass substrate having a size of 10 mm × 50 mm (thickness 1 mm) by a sputtering method. The thickness was 0.2 nm (2,000 angstroms).

Next, a Cu film for gate lines was formed on the ITO film to a thickness of about 0.3 μm by vapor deposition. This was designated as evaluation substrate A.

Next, a positive resist was applied to the evaluation substrate A to a thickness of 1 μm with a spinner. After the resist film was formed, prebaking was performed for 2 minutes in an environment of 100 ° C.

Next, exposure was performed using a photomask. The photomask used was a linear pattern with a width of 5 μm. Then, development was performed using tetramethylammonium hydroxide (TMAH). Thus, the exposed photoresist film was removed.

Next, etching was performed for 1 minute using an oxidant-based etchant heated to 40 ° C.
By this treatment, the Cu film other than the portion where the photoresist film remained was removed. The substrate after the treatment was washed with flowing pure water for 1 minute. The cleaned substrate was dried and stored for 1 minute in a spin drying apparatus at 8,000 rpm. At this time, nitrogen gas having a flow rate of 0.5 m <3> / s through a filter was blown from the rotation center. This is designated as an evaluation board B.

The evaluation substrate B has a photoresist film remaining as a pattern and a portion where the Cu film exposed by removing the photoresist film is etched. Note that the portion of the photoresist film remaining as a pattern also includes a portion having an area of 5 mm square in order to measure a contact angle described later.

<Effect of moisture on peelability> The influence of moisture in the resist stripper on the strippability of the resist film was prepared by examining resist strippers having different moisture content ratios and using evaluation substrate B. As a resist stripping solution sample, N-methyldiethanolamine (MDEA) was used as a tertiary alkanolamine, and propylene glycol (PG) and diethylene glycol monobutyl ether (BDG) were used as polar solvents.

The stripping solution sample is a polar solvent in which MDEA is 1, 2, 5, 8, 15% by mass, the moisture content is 40, 60, 80% by mass, respectively, and the remainder is mixed in a ratio of 3: 5 PG and BDG It was. Therefore, a total of 15 levels of stripping solution samples were prepared. Moreover, 100 ppm of resist components were dissolved in the resist stripping solution sample with respect to the total amount.

50 ml of each resist stripping solution sample prepared as described above was placed in a vial and heated to 40 ° C. with a water bath. The evaluation substrate B was immersed in the resist stripping solution sample in the vial for 1 minute while stirring at 500 rpm with a magnetic stirrer. Thereafter, the soaked evaluation substrate B was washed with pure water for 1 minute and dried by blowing nitrogen gas.

The peeled state of the developed resist film on the evaluation substrate B was visually confirmed. Further, the contact angle was measured on the Cu film after the resist film was peeled off. The contact angle was measured by the θ / 2 method in which pure water was used as a reagent and the contact angle was calculated from the radius and height of the droplet made of the reagent.

Fig. 1 shows the relationship between moisture content and contact angle. The horizontal axis represents the moisture content (% by mass) of the resist stripping solution. The vertical axis represents the contact angle (deg). In the figure, white circles are 1% by mass of N-methyldiethanolamine (MDEA), black circles are 2% by mass, black triangles are 5% by mass, white triangles are 8% by mass, and white squares are 15% by mass. The amount of polar solvent is the rest of MDEA and water. In addition, the resist component contained at 100 ppm with respect to the total amount of the resist stripping solution is not included in the description of the total amount (100%).

The contact angle of the Cu film after the resist film is peeled is considered to observe water repellency due to the resist component remaining as a protective film on the Cu film. That is, after removing the resist film with the resist stripping solution, the contact angle becomes small. For example, when the contact angle is measured on the resist film surface before peeling off the resist film, the contact angle is close to 50 to 70 °.

On the other hand, in most of the resist stripping liquid samples shown in FIG. 1, the contact angle is 30 ° or less, and the hydrophobic component (resist component) remains on the Cu film after the resist film is stripped. It is thought that it is not.

More specifically, the resist stripping solution sample containing 1% by mass of N-methyldiethanolamine (MDEA) had a low contact angle of 30 ° or less even when the moisture content increased. However, the contact angle did not decrease. On the other hand, the other resist stripping solution samples showed a decrease in contact angle as the moisture content increased.

MDEA makes the resist stripping solution alkaline, and the exposed resist film is dissolved in an alkaline solution, and MDEA makes the resist stripping solution alkaline. Therefore, it is considered that when the MDEA is less than 1% by mass, the resist stripping solution itself cannot dissolve the resist film.

Referring to 15% by mass of white square N-methyldiethanolamine (MDEA), the contact angle was as low as 21 ° at a moisture content of 60% by mass. However, when the moisture content was 80% by mass, the contact angle was 62 °. This is presumably because the total of MDEA (15% by mass) and moisture (80% by mass) was 95% by mass, and as a result, the polar solvent was reduced to 5% by mass. That is, it can be determined that the exposed resist film cannot be removed even if the amount of the polar solvent is too small.

Referring to the case where the white triangle MDEA is 8% by mass, even if the moisture content is 80% by mass (the total amount of MDEA and water is 88% by mass), the contact angle is 25 ° or less. % Or more is considered good.

In FIG. 1, it can be seen that MDEA, which is a tertiary alkanolamine, can be used in a range of 1 to 8% by mass and a moisture content of 40 to 80% by mass. However, when the moisture content is higher than 80% by mass, the resist film itself is peeled off visually, which is not suitable as a resist stripping solution.

From the above, the composition of the moisture content is 40 to 80% by mass with respect to the total amount of the resist stripping solution, the tertiary amine is 1 to 8% by mass, and the remainder is the polar solvent. Can be kept clean. If the water content is 40 to 60% by mass, the tertiary amine can be increased to 15% by mass.

<Cu anticorrosion> The anticorrosion of the Cu film is called "Cu anticorrosion" and was evaluated according to the following procedure. For the evaluation substrate A, the film thickness before dipping (t1 nm) of the Cu film before dipping was measured. 50 ml of a resist stripping solution prepared at a predetermined composition ratio was dispensed into a vial. The resist stripping solution was heated to 40 ° C. with a water bath while still in the vial. The prepared evaluation substrate A was placed in the resist stripping solution at 40 ° C. and immersed for 30 minutes while stirring at 500 rpm with a magnetic stirrer.

After the immersion, the evaluation substrate A was pulled up from the peeling solution and washed with flowing pure water for 1 minute. After washing, the film was dried for 2 minutes with dry air (nitrogen gas) at a flow rate of 0.8 m 3 / s. And the film thickness (t2) after process of Cu on the evaluation board | substrate A after immersion was measured. The etching rate was determined as (t1-t2) / 30 (nm / min).

FIG. 2 shows a graph in which the influence of the moisture content on the etching rate of the resist stripping solution with respect to Cu is examined. The horizontal axis is the moisture content (% by mass), and the vertical axis is the etching rate (nm / min) of the Cu film. The method of preparing the resist stripping solution sample is the same as in the case of <Effect of moisture on stripping property>. A tertiary alkanolamine, N-methyldiethanolamine (MDEA), a polar solvent, propylene glycol (PG), and diethylene glycol monobutyl ether (BDG) were mixed at a ratio of 5:24:40.

In this composition, even when the ratio of water is 50% by mass, MDEA is contained in 3.6% by mass of the entire resist stripping solution. Moreover, the ratio of PG and BDG is always 3: 5.

The resist stripping solution is alkaline due to the presence of tertiary alkanolamine. Cu is dissolved and etched (damaged) by the alkaline water.

Referring to FIG. 2, the etching rate increased as the moisture content increased. However, when the moisture content was 40% by mass or more, the etching rate was saturated. Therefore, it can be said that the damage to the Cu film does not change much even if the moisture content increases. That is, the resist stripping solution having a moisture content of 40 to 80% by mass shown in FIG. 1 can be used practically without any problem.

As described above, the resist stripping solution according to the present invention having a moisture content of 40 to 80% by mass can strip the resist film, does not leave the protective film on the Cu surface after stripping the resist film, and the stripped resist film Therefore, the resist film can be peeled off without forming an organic layer on the Cu surface.

The stripping solution of the present invention can be suitably used in general for FPDs such as liquid crystal displays, plasma displays, organic ELs, etc., which are manufactured by wet etching using a Cu film as a conducting wire, and particularly require a large area and fine processing. it can.

Claims (6)

1. 40-60 mass% water,
   1 to 15% by weight of a tertiary alkanolamine,
   A photoresist stripping solution comprising 25 to 59% by mass of a polar solvent.
2. More than 60% by weight and less than 80% by weight water,
   1 to 8% by weight of a tertiary alkanolamine,
   A photoresist stripping solution comprising 12 to 39% by mass of a polar solvent.
3. 3. The photoresist stripping solution according to claim 1, further comprising 1 to 3000 ppm of a resist component.
4. The said polar solvent consists of propylene glycol and diethylene glycol monobutyl ether, The ratio of the said diethylene glycol monobutyl ether with respect to the said polar solvent is 5/8 or more, The claim of any one of Claim 1 thru | or 3 characterized by the above-mentioned. The photoresist stripping solution described.
5. The photoresist stripping solution according to any one of claims 1 to 4, wherein the tertiary alkanolamine is N-methyldiethanolamine.
6. The resist stripping solution according to any one of claims 3 to 5, wherein the resist component is a component from an exposed positive-type photoresist.

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