JP5809444B2 - Stripper for photoresist - Google Patents

Description

  The present invention relates to a photoresist stripping solution. In particular, the present invention relates to a photoresist 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 Cu has a lower protective property for the 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.

  When Cu is used as the wiring material, the problem 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, and an unnecessary portion of the Cu film is removed with an etchant that dissolves Cu. The desired wiring pattern can be obtained by removing the resist.

  Here, the Cu film is corroded in the final resist film peeling step. In this step, since the resist adhering to the Cu film surface disappears, the Cu film surface is directly exposed to the stripping solution. In particular, the resist stripping solution shows alkalinity and also contains water. Therefore, the Cu film is easily corroded. In view of this, development of a photoresist stripping solution that achieves a good balance between stripping the photoresist 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 to 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 the 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 5-45 wt%, (b) polar organic solvent and water are 50-94.95 wt%, (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 proposes a method for manufacturing a semiconductor device in which a copper wiring pattern is formed on a substrate and then the copper wiring pattern is washed with an aqueous solution containing 2 × 10 ⁻⁶ to 10 ⁻¹ mol · dm ^{−3 of} benzotriazole. Has been.

  Furthermore, in the wet etching method, various solutions including a stripping solution 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 such a viewpoint, Patent Document 4 discloses a stripping solution composed of a polyhydric alcohol, an alkanolamine, water, a glycol ether, and an anticorrosive agent. 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.

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

  In Patent Document 1, the etching of Cu 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 an oxidant-based etchant that wet-etches Cu, the resist layer is altered and is difficult to peel off. That is, the photoresist stripping solution disclosed in Patent Document 1 cannot be simply applied as a photoresist stripping solution used in the step of wet-etching Cu or Cu alloy.

  Patent Document 2 considers this point, and exactly discloses a photoresist stripping solution 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.

  Patent Document 3 discloses that BTA (benzotriazole) is in contact with 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 on the Cu film is peeled off. The formation of insoluble compounds. 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 regeneration (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 the present invention, when a Cu or Cu alloy layer on a large-area substrate is wet-etched to form a wiring or the like, the photoresist that has been exposed, altered, and difficult to peel is not damaged to the Cu film. A photoresist stripping solution that peels and does not reduce the adhesion between the film formed on the Cu film, and resist releasability, Cu film corrosion resistance and Cu film even after repeated recycling And a photoresist stripping solution capable of continuing to maintain adhesion to the formed film on the Cu film.

  In order to solve the above-mentioned problems, it is necessary to use a corrosion inhibitor that can be easily separated from the component of the release agent. The inventor of the present invention, as a result of earnest studies, the combination of the photoresist itself exposed and stripped with a stripping solution and the stripping solution with low corrosiveness of the Cu film does not corrode the Cu film, and It was confirmed that the resist film could be dissolved, and the present invention was completed.

  The photoresist stripping solution of the present invention is characterized in that a tertiary amine is used as a main agent and a resist component is used as a component that is considered to have an effect as a corrosion inhibitor. Further, the present invention does not include a corrosion inhibitor added in a trace amount typified by a benzotriazole-based compound.

More specifically, the photoresist stripping solution of the present invention comprises:
A stripping solution for stripping and repeatedly using a photoresist coated on a Cu film, wherein tertiary alkanolamine is 1 to 9% by mass, polar solvent is 10 to 70% by mass, water is 10 to 40% by mass and repeated. resist components of the stripping solution to be used Ri Tona only 500ppm or ~3000ppm less, the polar solvent is characterized with diethylene glycol monobutyl ether, a mixed solvent der Rukoto propylene glycol.

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.

  Moreover, in the said stripping solution for photoresists, the said stripping solution is stripping solution for stripping the positive type photoresist apply | coated on Cu film | membrane.

In the present invention, there is corrosion resistance of the Cu film, and adhesion with the layer formed on the Cu film is also good. Moreover, the stripping solution can be recycled stably. Further, the resist component is used as a corrosion inhibitor for Cu film. 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.

  Further, it can be considered that the corrosion inhibitor and the resist dissolution aid are present on the resist side. Therefore, a remanufactured stripping solution can be prepared by controlling the component ratio of tertiary alkanolamine, polar solvent, and water without a trace additive. Therefore, management of the reclaimed stripping solution is easy.

The photoresist stripping solution of the present invention is a stripping solution for stripping and repeatedly using a photoresist coated on a Cu film, wherein the tertiary alkanolamine is 1 to 9% by mass, the polar solvent is 10 to 70% by mass, water 10 to 40% by weight, and repeating the resist components of the stripping solution to be used Ri Tona only 500ppm or ~3000ppm less, the polar solvent is a diethylene glycol monobutyl ether, Ru mixed solvent der propylene glycol. In addition, including this specification and a claim, tertiary alkanolamine, a polar solvent, and water are called a solution component for convenience. Tertiary alkanolamines are also called amines or tertiary amines.

  As the tertiary alkanolamine, specifically, the following can be suitably used. 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 monobutyl ether And polyhydric alcohols such as diethylene glycol monoalkyl ether (wherein 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 corrosion resistance to the substrate. Of these, diethylene glycol monobutyl ether and N-methyl-2-pyrrolidone are particularly preferable. These components may be used in combination of a plurality of types.

  The water is preferably pure water, but may contain impurities as long as it is industrially usable. 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.

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

  Therefore, in the present invention, the “resist component” may be a component in which the component of the photoresist before being exposed is changed. In other words, even a component that is not contained in the photoresist before being exposed is associated with a stripping solution or a component that is contained in the exposed photoresist or dissolved in the solution component from the exposed photoresist. Any component that changes and melts in

  When the inventor of the present invention dissolves the photoresist coated and exposed on the Cu film with solution components (tertiary alkanolamine, polar solvent, and water), the corrosion of the Cu film is not substantially problematic. The present invention has been completed by confirming that it can be suppressed and the solubility of the resist 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 indene ketene encounters water, it undergoes a hydrolysis reaction and changes to indene carboxylic acid.

  Indenecarboxylic acid dissolves in an alkaline solution because it is soluble. As a result, the melting point of the resin is exposed to the alkaline solution, and the photoresist 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.

  Moreover, the stripping solution containing these components does not inhibit dissolution of the exposed resist itself. Although this is shown by the Example mentioned later, since it is the component which melt | dissolved from the resist film | membrane exposed originally, it is thought that it does not raise | generate reattachment or a recombination etc. in the melt | dissolution location of a film | membrane.

  In addition, when the stripping solution of the present invention is used for a Cu film on which an exposed photoresist is formed, the stripping solution to be initially introduced may not have a resist component. This is because the resist component can be obtained from the exposed resist.

  In the stripping solution of the present invention, although not clear, it is considered that the resist component is responsible for preventing corrosion of the Cu film surface. Therefore, the stripping solution for starting use is supplied from the exposed photoresist on the Cu film even if it does not contain a resist component. However, in other words, the concentration of the resist component in the stripping solution increases with repeated use. Since the resist component includes a resin constituting the resist, 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 for 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 increases from zero to 3000 ppm.

  Since it is thought that the stripping solution of the present invention has 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, and the Cu film substantially remains in the presence of the resist component. It is necessary to have a corrosive power to the extent that it does. 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 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 1 to 9% by weight, more preferably 2 to 7% by weight, most preferably 4 to 6% by weight based on the total amount of the stripping solution. Is preferred. This is because if the content is 9% by mass or more, the Cu film is corroded even if the resist component is included. Further, when the amount is 1% by mass or less, the photoresist cannot be peeled off.

  As shown in the examples described later, the pH value of the tertiary alkanolamine is not much different from that of the primary and secondary alkanolamine. However, the acid dissociation constant (pKa) of the primary alkanolamine MEA (monoethanolamine) is 9.55, while the tertiary alkanolamine MDEA (N-methyldiethanolamine) is 8.52. is there. That is, the degree of alkali is lower in MDEA. For this reason, it is thought that tertiary alkanolamine has a lower corrosive power to the Cu film surface.

  Another way of looking at it is to consider the following way of thinking. For primary and secondary amines, the hydroxyl group still remains in the nitrogen. This hydroxyl group is considered to easily trap the above-mentioned indenecarboxylic acid. On the other hand, in the tertiary amine, the hydroxyl group bonded to nitrogen is replaced with another functional group and does not inhibit the movement of indenecarboxylic acid. Therefore, in the primary and secondary amines, the indenecarboxylic acid generated from the resist film cannot be bonded to the Cu film surface, and the surface of the Cu film is corroded. On the other hand, in the presence of a tertiary amine, the indene carboxylic acid produced in the solution forms a protective layer on the Cu film without being inhibited by the tertiary amine.

  In addition, both reactions are considered to occur together. In any case, the combination of tertiary alkanolamine, polar solvent and water hardly corrodes the Cu film when the resist film is removed from the Cu film on which the exposed resist film is formed.

  The ratio of the polar solvent is 10 to 70% by mass, more preferably 30 to 70% by mass, and most preferably 50 to 70% by mass with respect to the total amount of the stripping solution. Moreover, 10-40 mass% of water, More preferably, 20-40 mass%, Most preferably, 30-40 mass% is suitable. Within the above composition range, the polar solvent and water may be prepared so that the viscosity of the stripping solution, which is a mixed solution of a tertiary alkanolamine, is suitable at the temperature used.

  Further, the temperature of the reaction between the resin or the photosensitizer in the photoresist and the stripping solution is very related. 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.

<Method for producing evaluation substrate>
In order to show the effect of the photoresist stripping solution of the present invention, an evaluation substrate was prepared by the following procedure. This is usually a process using a 6-inch wafer and is called a spin processor. First, ITO (Indium Tin Oxide: transparent electrode) was formed on a 6-inch wafer-shaped glass substrate (thickness 1 mm) by sputtering. The thickness was 0.2 μm (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. Next, a positive resist was applied 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, it exposed using the photomask. The photomask used was a linear pattern with a width of 5 μm. Then, development was performed using tetramethylammonium hydroxide (TMAH). This removed the exposed portion of the photoresist.

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 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 passed through the filter was blown from the center of rotation.

<Cu film corrosion prevention>
The corrosion prevention property of the Cu film was evaluated by the following procedure. First, the substrate was cut into 10 mm × 60 mm strips so that the gate lines (made of Cu film) were in the longitudinal direction. 20 ml of stripping solution prepared with the composition shown in Table 1 was dispensed into a vial (30 ml). Then, the peeling solution was heated to 40 ° C. with a water bath while still in the vial. And the prepared evaluation board | substrate was put in the peeling liquid which became 40 degreeC, and it was immersed for 30 minutes. In addition, since this evaluation is an experiment for investigating how much the stripping solution corrodes Cu, it was immersed for a long time of 30 minutes.

  After immersion, the evaluation substrate was pulled up from the stripping solution and washed with flowing pure water for 1 minute. After washing, it was dried with dry air. Dry air was passed through the filter, but the temperature was room temperature. The surface and cross section of the treated substrate were observed by SEM (Scanning Electron Microscope), and the Cu concentration of the stripping solution remaining in the vial was analyzed by atomic absorption spectrometry.

  For observation with SEM, evaluation was performed according to the following criteria. Those that did not show corrosion in the 800 × plane observation and the 3000 × cross-sectional observation by SEM were marked as “no corrosion”. In addition, although both the line width and the film thickness decreased, the wiring remaining was marked as “corrosion” with a triangle mark. Also, those with no wiring were marked as crosses with severe “corrosion”. Each mark is shown in Table 1.

<Resist peelability>
The peelability of the photoresist was evaluated by the same procedure as the corrosion resistance of the Cu film. Specifically, it was performed as follows. First, the substrate was cut into 10 mm × 60 mm strips so that the gate lines (made of Cu film) were in the longitudinal direction. 20 ml of stripping solution prepared with the composition shown in Table 1 was dispensed into a vial (30 ml). Then, the peeling solution was heated to 40 ° C. with a water bath while still in the vial. And the prepared evaluation board | substrate was put in the peeling liquid which became 40 degreeC, and it was immersed for 30 seconds.

  After immersion, the evaluation substrate was pulled up from the stripping solution and washed with flowing pure water for 1 minute. After washing, it was dried with dry air. Dry air was passed through the filter, but the temperature was room temperature. The surface of the treated substrate was observed with an SEM.

  In the observation with SEM, the peelability was evaluated according to the following criteria. When there was no resist residue over the entire length of the evaluation substrate (60 mm) by plane observation at 800 times with SEM, it was circled as “no residue”. Further, when there is a residue or when there is no meaning to evaluate the corrosion of the Cu film violently, a minus sign (“−”) is given as “not evaluated”.

<Resist solubility>
The resist solubility with respect to the stripping solution was evaluated as follows. In this embodiment, since the photoresist is exposed to an oxidant etchant, it is denatured and cannot be easily removed. First, the substrate was cut into 20 mm × 60 mm strips so that the gate lines (made of Cu film) were in the longitudinal direction. 50 ml of the stripping solution prepared with the composition shown in Table 1 was dispensed into a vial (50 ml). Then, the peeling solution was heated to 40 ° C. with a water bath while still in the vial. Then, the prepared evaluation substrate was put in the stripping solution at 40 ° C., and the time until the resist was lifted was measured with a stopwatch.

  The resist solubility was evaluated according to the following criteria. When the resist was dissolved within 30 seconds after the evaluation substrate was immersed in the stripping solution, it was marked as “having sufficient dissolving power”. If it took 30 seconds or more, it was marked with a cross mark as “the solubility of the photoresist was not sufficient”.

<Film peeling>
Even if the photoresist modified by exposure to the oxidant etchant is sufficiently dissolved and the Cu film is not corroded, the corrosion inhibitor remains on the surface of the Cu film, and adhesion to the film formed thereon If it is bad, it is not practical. Therefore, the following evaluation was performed on the assumption that the amount of the corrosion inhibitor on the surface of the Cu film is small enough to cause no practical problem, in other words, the degree that the film can be formed on the Cu film without any practical problem.

First, the substrate was cut into 10 mm × 60 mm strips so that the gate lines (made of Cu film) were in the longitudinal direction. 20 ml of stripping solution prepared with the composition shown in Table 1 was dispensed into a vial (30 ml). Then, the peeling solution was heated to 40 ° C. with a water bath while still in the vial. And the evaluation board | substrate prepared in the peeling liquid which became 40 degreeC was immersed for 30 second. Next, it was taken out from the stripping solution and washed with running pure water for 1 minute. After washing, it was dried for 2 minutes with dry air at a flow rate of 0.8 m ³ / s at room temperature.

Then, an insulating film (SiO ₂ ) was formed to a thickness of 0.1 μm on the surface of the substrate on which the Cu film was formed by sputtering. Then, gold was further formed on the insulating film by about 0.01 μm by sputtering, and SEM observation was performed at a magnification of 1,000 times. Film peeling was evaluated according to the following criteria. When the film was formed integrally on the Cu film, it was marked as “No film peeling”. In addition, when there was a part of the edge portion or flat portion of the Cu film that was recognized as a SiO ₂ peeling or a hole, it was marked as “film peeling”. If the insulating film on the Cu film is not completely insulated, it causes a short circuit and immediately leads to a defect. Therefore, it is necessary to strictly evaluate the insulating film.

  In addition to the above evaluation, the composition and pH of the stripping solution are shown in Table 1. For comparison, monoethanolamine (MEA) which is a primary alkanolamine and N-methyldiethanolamine (MDEA) which is a tertiary alkanolamine were used for comparison. As comparative examples, benzotriazole (BTA), pyrocatechol, vitamin C, and sorbitol were used as corrosion inhibitors. The composition and evaluation results of Examples and Comparative Examples are described below.

( Reference Example 1)
The composition of the stripping solution was prepared as follows. MDEA (N-methyldiethanolamine) was 5% by mass as amines, BDG (diethylene glycol monobutyl ether) was 40% by mass, PG (propylene glycol) was 24% by mass, and water was 31% by mass as a polar solvent. The pH was 10.6.

  Although the corrosion resistance of the Cu film was triangular as an evaluation, the evaluation was round for both the resist peelability, the resist solubility, and the peeling of the insulating film laminated on the copper layer. Although the elution amount of copper in the stripping solution was 0.79 ppm, there was no practical problem at all. In addition, although it did not put in the comparative example, it confirmed that the stripping solution of Example 1 had a bad evaluation of Cu film corrosion resistance against the sample of only the Cu film not forming the resist film. Yes.

( Reference Example 2)
The composition of the stripping solution was prepared as follows. MDEA (N-methyldiethanolamine) was 5 mass% as amines, BDG (diethylene glycol monobutyl ether) was 40 mass%, PG (propylene glycol) was 24 mass%, and water was 30.99 mass% as a polar solvent. These are called solution components.

  The resist component was prepared as follows. First, a positive resist was applied on a glass substrate with a spinner to a thickness of 1 μm. The positive resist used here is the same resist used when the evaluation substrate is manufactured. Next, this resist film was exposed. The exposure conditions are also the same as those used when producing the evaluation substrate. The exposed resist film formed on the glass substrate was dissolved with a solution component, and the weight of the resist film formed on the glass substrate was determined from the difference in substrate weight before and after dissolution of the resist film. That is, the “exposed glass substrate with a resist film” produced in the same manner can obtain a stripping solution containing a predetermined resist component when the resist film is dissolved in the solution component. Hereinafter, this is referred to as “exposure resist film piece”.

  The exposed resist film piece becomes a resist component when it is dissolved in the solution component. 0.01% by mass of an exposed resist film piece was prepared and mixed in a solution component warmed to 40 ° C. The exposed resist film piece was easily dissolved. A mixture of MDEA, BDG, PG, water, and exposed resist film pieces was used as the stripping solution of this example. The pH was 10.4.

  Although the corrosion resistance of the Cu film was triangular as an evaluation, the evaluation was round for both the resist peelability, the resist solubility, and the peeling of the insulating film formed on the Cu film. In addition, although the elution amount of copper in the stripping solution was 0.77 ppm, there was no problem in practical use.

(Example 3)
The composition of the stripping solution was prepared as follows. MDEA (N-methyldiethanolamine) 5 mass% as amines, BDG (diethylene glycol monobutyl ether) 40 mass% as polar solvent, PG (propylene glycol) 24 mass%, water 30.95 mass% Was 0.05 mass%. The pH was 10.2.

  All the evaluations of corrosion resistance of the Cu film, peelability of the resist, solubility of the resist, and peeling of the insulating film formed on the Cu film were round. Although the elution amount of copper in the stripping solution was 0.35 ppm, there was no practical problem at all.

Example 4
The composition of the stripping solution was prepared as follows. MDEA (N-methyldiethanolamine) 5% by weight as amines, BDG (diethylene glycol monobutyl ether) 40% by weight, PG (propylene glycol) 24% by weight, water 30.9% by weight Was 0.1% by mass. The pH was 10.0.

  All the evaluations of corrosion resistance of the Cu film, peelability of the resist, solubility of the resist, and peeling of the insulating film formed on the Cu film were round. Although the elution amount of copper in the stripping solution was 0.30 ppm, there was no problem in practical use.

(Example 5)
The composition of the stripping solution was prepared as follows. MDEA (N-methyldiethanolamine) 5 mass% as amines, BDG (diethylene glycol monobutyl ether) 40 mass% as polar solvent, PG (propylene glycol) 24 mass%, water 30.8 mass% Was 0.2 mass%. The pH was 9.9.

  All the evaluations of corrosion resistance of the Cu film, peelability of the resist, solubility of the resist, and peeling of the insulating film formed on the Cu film were round. In addition, although the elution amount of copper in the stripping solution was 0.26 ppm, there was no problem in practical use.

(Example 6)
The composition of the stripping solution was prepared as follows. MDEA (N-methyldiethanolamine) 5 mass% as amines, BDG (diethylene glycol monobutyl ether) 40 mass% as polar solvent, PG (propylene glycol) 24 mass%, water 30.7 mass% Was 0.3 mass%. The pH was 9.8.

  All the evaluations of corrosion resistance of the Cu film, peelability of the resist, solubility of the resist, and peeling of the insulating film formed on the Cu film were round. Although the elution amount of copper in the stripping solution was 0.23 ppm, there was no practical problem.

(Comparative Example 1)
The composition of the stripping solution was prepared as follows. MDEA was 5% by mass as amines, BDG was 40% by mass as a polar solvent, PG was 24% by mass, BTA was 0.1% by mass as a corrosion inhibitor, and water was 30.9% by mass. The pH was 10.0.

  The evaluation of the corrosion resistance of the Cu film and the peelability of the resist were rounded. However, both the solubility of the resist and the peeling of the insulating film formed on the Cu film were evaluated as bad. The elution amount of copper in the stripping solution was less than 0.05 ppm. This is because the resist solution was poor and the stripping solution did not erode the surface of the Cu film. Although the Cu film corrosion resistance was improved, the insulating film formed on the upper part of the Cu film was peeled off.

(Comparative Example 2)
The composition of the stripping solution was prepared as follows. As amines, MEA (monoethanolamine) was 5% by mass, BDG was 42% by mass as a polar solvent, PG was 18% by mass, BTA was 0.1% by mass as a corrosion inhibitor, and water was 34.9% by mass. . The pH was 10.7.

  The corrosion resistance of the Cu film was evaluated. The surface of the Cu film was severely corroded and the Cu film disappeared, and the peelability could not be evaluated. The resist solubility was evaluated as a circle. Of course, since the Cu film itself was lost, the evaluation of the peelability of the insulating film was not worthy of evaluation.

(Comparative Example 3)
The composition of the stripping solution was prepared as follows. As amines, MEA (monoethanolamine) was 5% by mass, BDG was 42% by mass as a polar solvent, PG was 18% by mass, BTA was 0.49% by mass as a corrosion inhibitor, and water was 34.51% by mass. . The pH was 10.5.

  The corrosion resistance of the Cu film was evaluated. The surface of the Cu film was severely corroded and the Cu film disappeared, and the peelability could not be evaluated. The resist solubility was evaluated as a circle. Of course, since the Cu film itself was lost, the evaluation of the peelability of the insulating film was not worthy of evaluation.

(Comparative Example 4)
The composition of the stripping solution was prepared as follows. As amines, MEA (monoethanolamine) was 5% by mass, BDG was 42% by mass as a polar solvent, PG was 18% by mass, BTA was 0.98% by mass as a corrosion inhibitor, and water was 34.02% by mass. . The pH was 10.5.

  The corrosion resistance of the Cu film was evaluated. The surface of the Cu film was severely corroded and the copper layer disappeared, and the peelability could not be evaluated. The resist solubility was evaluated as a circle. Of course, since the Cu film itself was lost, the evaluation of the peelability of the insulating film was not worthy of evaluation.

(Comparative Example 5)
The composition of the stripping solution was prepared as follows. As amines, MEA (monoethanolamine) was 5 mass%, BDG was 42 mass% as a polar solvent, PG was 18 mass%, pyrocatechol was 5 mass% as a corrosion inhibitor, and water was 30 mass%. The pH was 10.3.

  The corrosion resistance of the Cu film was evaluated. The surface of the Cu film was severely corroded and the Cu film disappeared, and the peelability could not be evaluated. The resist solubility was evaluated as a circle. Of course, since the Cu film itself was lost, the evaluation of the peelability of the insulating film was not worthy of evaluation.

(Comparative Example 6)
The composition of the stripping solution was prepared as follows. MEAs (monoethanolamine) was 20% by mass as amines, BDG was 60% by mass as a polar solvent, pyrocatechol was 5% by mass as a corrosion inhibitor, and water was 15% by mass. The pH was 11.2.

  The corrosion resistance of the Cu film was evaluated. The surface of the Cu film was severely corroded and the Cu film disappeared, and the peelability could not be evaluated. The resist solubility was evaluated as a circle. Of course, since the Cu film itself was lost, the evaluation of the peelability of the insulating film was not worthy of evaluation.

(Comparative Example 7)
The composition of the stripping solution was prepared as follows. 5% by mass of MEA (monoethanolamine) as an amine, 42% by mass of BDG as a polar solvent, 18% by mass of PG, 1% by mass of BTA as a corrosion inhibitor, 1% by mass of vitamin C, and 33% of water %. The pH was 10.3.

  The corrosion resistance of the Cu film was evaluated. The surface of the Cu film was severely corroded and the Cu film disappeared, and the peelability could not be evaluated. The resist solubility was evaluated as a circle. Of course, since the Cu film itself was lost, the evaluation of the peelability of the insulating film was not worthy of evaluation.

(Comparative Example 8)
The composition of the stripping solution was prepared as follows. 5% by mass of MEA (monoethanolamine) as an amine, 42% by mass of BDG as a polar solvent, 18% by mass of PG, 1% by mass of BTA as a corrosion inhibitor, 1% by mass of sorbitol, 33% by mass of water It was. The pH was 10.5.

  The corrosion resistance of the Cu film was evaluated. The surface of the Cu film was severely corroded and the Cu film disappeared, and the peelability could not be evaluated. The resist solubility was evaluated as a circle. Of course, since the Cu film itself was lost, the evaluation of the peelability of the insulating film was not worthy of evaluation.

(Comparative Example 9)
The composition of the stripping solution was prepared as follows. MDEA was 5% by mass as amines, BDG was 40% by mass as a polar solvent, PG was 24% by mass, BTA was 1% by mass as a corrosion inhibitor, 1% by mass of sorbitol, and 29% by mass of water. The pH was 9.1.

  The evaluation of the corrosion resistance of the Cu film and the peelability of the resist were rounded. However, both the solubility of the resist and the peeling of the insulating film formed on the Cu film were evaluated as bad. The elution amount of copper in the stripping solution was less than 0.05 ppm. This is because the resist solution was poor and the stripping solution did not erode the surface of the Cu film. Although the Cu film corrosion resistance was improved, the insulating film laminated on the upper part of the Cu film was peeled off.

  Comparative Example 1 has the same solution configuration as that of the example, and the difference is that the corrosion inhibitor is a resist component or BTA. The solution component containing MDEA (N-methyldiethanolamine) as a main component originally has a corrosive action on the Cu film. However, corrosion can be suppressed within a practically acceptable range by BTA and resist components. Here, in the examples, the resist solubility was a round evaluation, whereas in Comparative Example 1 (BTA), the resistance was bad.

Considering that Reference Example 1 does not contain a corrosion inhibitor, it is considered that the solution components themselves of Examples and Comparative Example 1 can dissolve the resist. Then, it was considered that the resist did not dissolve in Comparative Example 1 due to the influence of BTA which is a corrosion inhibitor. That is, the component added as a corrosion inhibitor is considered to suppress the solubility of the resist film itself to some extent.

  On the other hand, the resist component that has been dissolved in the solution component from the exposed resist component has the function of a corrosion inhibitor, and it can be said that the solution component of the stripping solution has an effect that does not hinder the dissolution of the exposed resist. .

  Comparative Examples 2 to 8 are samples in which the main component of the solution component is changed to MEA (monomethyl ether). MEA, which is a primary amine, is highly corrosive, and even when a considerable amount of BTA, pyrocatechol, vitamin C, or sorbitol was added as a corrosive agent, the corrosive force could not be suppressed.

  In Comparative Example 9, the main component of the solution component is returned to MDEA, and 2% by mass of BTA and sorbitol are added. However, although the anti-corrosion effect on the Cu film was recognized, the resist solubility as in Comparative Example 1 was an evaluation.

  From the above results, it can be seen that the stripping solution of the present invention has a very weak corrosion effect on the Cu film, can also dissolve the resist, and has good adhesion to the layer formed on the Cu film. It was. Further, as described above, since the resist component is made of a photosensitizer (or a material in which it is changed) and a resin, it can be easily separated from the solution component in the stripping solution. Therefore, even if it is used repeatedly and becomes a waste liquid, only the solution component can be separated and recovered.

  More specifically, amines and polar solvents can be separated and recovered together. By preparing a calibration curve or the like in advance, the component ratio can be easily known. Therefore, the replenisher can be regenerated by replenishing a deficiency with respect to a predetermined component composition ratio and further adding water. In addition, since there is no trace amount of additive in this reclaimed stripping solution, there is no possibility that the trace amount component will be concentrated no matter how many times the regeneration is performed. That is, the stripping solution can be recycled stably.

  The stripping solution of the present invention is suitable for use in general 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, particularly in a large area and requiring fine processing. Can do.

Claims (4)

A stripping solution for stripping and repeatedly using a photoresist coated on a Cu film, wherein tertiary alkanolamine is 1 to 9% by mass, polar solvent is 10 to 70% by mass, water is 10 to 40% by mass and repeated. resist components of the stripping solution to be used Ri Tona only 500ppm or ~3000ppm less, the polar solvent is Ru mixed solvent der diethylene glycol monobutyl ether and propylene glycol photoresist stripping solution.   2. The photoresist stripping solution according to claim 1, wherein the tertiary alkanolamine is N-methyldiethanolamine (MDEA). 3. The photoresist stripping solution according to claim 1 , wherein the resist component is a component from an exposed positive photoresist. 4. The stripping solution for photoresist according to any one of claims 1 to 3 , wherein the stripping solution is a stripping solution for stripping a positive photoresist applied on a Cu film.