JP2014240949A - Resist stripping solution and resist stripping method - Google Patents

Abstract

To provide a resist stripping solution and a resist stripping method capable of stripping a heat-reactive resist mainly composed of copper oxide with no residual film and high throughput. A resist stripping solution is a resist stripping solution for a heat-reactive resist containing copper oxide as a main component and having a pH of less than 0. The resist stripping solution contains at least sulfuric acid. A fine pattern is given to a resist film made of a heat-reactive resist that is stripped with a resist stripping solution. [Selection figure] None

Description

  The present invention relates to a resist stripping solution and a resist stripping method, and more particularly to a resist stripping solution and a resist stripping method for a heat-reactive resist.

  In recent years, as the demand for higher density and higher integration in the fields of semiconductors, optical / magnetic recording, etc., fine pattern processing technology of several hundred nm to several tens of nm or less is indispensable. Therefore, in order to realize such fine pattern processing, elemental technologies of each process such as a mask / stepper, exposure, resist material and the like are actively studied.

  Although many studies have been made on resist materials, at present, the most common resist materials are photoreactive organic resists (hereinafter also referred to as photoresists) that react with exposure light sources such as ultraviolet light, electron beams, and X-rays. (See Patent Document 1 and Non-Patent Document 1).

In the laser beam used for exposure, the intensity of the laser beam focused by a lens usually shows a Gaussian distribution shape as shown in FIG. At this time, the spot diameter is defined as 1 / e ² . In general, a photoresist reaction is initiated by absorbing energy represented by E = hν (E: energy, h: Planck constant, ν: wavelength). Therefore, the reaction does not strongly depend on the intensity of light, but rather depends on the wavelength of the light, so that almost all reaction occurs in the portion irradiated with light (exposed portion). For this reason, when a photoresist is used, exposure is performed faithfully to the spot diameter.

  Although a method using a photoreactive organic resist is a very effective method for forming a fine pattern of about several hundreds of nanometers, a finer pattern is formed because a photoreactive photoresist is used. Therefore, it is necessary to perform exposure with a spot smaller than the pattern required in principle. Therefore, a KrF or ArF laser having a short wavelength must be used as the exposure light source. However, since these light source devices are very large and expensive, they are not suitable from the viewpoint of manufacturing cost reduction. Furthermore, when an exposure light source such as an electron beam or X-ray is used, the exposure atmosphere needs to be in a vacuum state, so a vacuum chamber is used, and there are considerable limitations from the viewpoint of cost and enlargement.

  On the other hand, when an object is irradiated with laser light having a distribution as shown in FIG. 1, the temperature of the object also exhibits the same Gaussian distribution as the intensity distribution of the laser light. At this time, if a resist that reacts at a certain temperature or higher, that is, a heat-reactive resist is used, the reaction proceeds only at a portion that exceeds a predetermined temperature as shown in FIG. It becomes. That is, a pattern finer than the spot diameter can be formed without reducing the wavelength of the exposure light source. Therefore, the influence of the exposure light source wavelength can be reduced by using the heat-reactive resist.

  So far, techniques for forming a fine pattern by exposure using a semiconductor laser or the like and heat / photoreaction using a metal oxide as a heat-reactive resist have been reported (hereinafter, Patent Documents 2 to 4, Non-Patent Document 2). reference). Such metal oxide can change the degree of oxidation by heating by exposure, and make a difference in solubility in the etching solution due to the difference in the degree of oxidation. A fine pattern can be formed. The inventors of the present application have invented an etching solution for a heat-reactive resist containing, for example, copper oxide as a main component, as an etching solution for the above-mentioned heat-reactive resist (refer to Patent Documents 5 to 7 below).

JP 2007-144959 A Japanese Patent No. 4055543 Japanese Patent No. 4986137 Japanese Patent No. 4986138 International Publication No. 2011/105129 Pamphlet JP 2011-144377 A JP 2012-1757 A

Published by Information Organization Co., Ltd. “Latest Resist Materials” P.59-P.76 The 19th Symposium on Phase Change Optical Information Storage 2007 Proceedings P.77-P.80

  However, there is currently no resist stripping solution for the thermal reaction type resist, which effectively strips the resist that is no longer necessary after pattern formation. The reason for this is that what is generally developed as a resist stripper is intended for use in organic resists. That is, organic solvents, alkalis, mild aromatic organic acids, and the like are effectively used for stripping organic resists. In these stripping solutions for organic resists, a heat-reactive resist mainly composed of inorganic copper oxide is used. It is difficult to exfoliate effectively. Furthermore, since the thermal reaction type resist mainly composed of copper oxide is crystallized when heated, the base material and the crystallized resist are in close contact with each other particularly at the interface with the base material. A very thin film with a low solubility of 1 nm or less is formed in the vicinity of the interface. Therefore, even if most of the resist is removed with a stripping solution, these thin resist films remain. For this reason, a resist stripping solution for a heat-reactive resist that can remove such a thin resist film remaining in the vicinity of the substrate interface is desired.

  The present invention has been made in view of this point, and an object thereof is to provide a resist stripping solution and a resist stripping method capable of stripping a heat-reactive resist mainly composed of copper oxide without a residual film.

  The resist stripping solution of the present invention is a resist stripping solution for a heat-reactive resist containing copper oxide as a main component, and has a pH of less than 0.

  In the resist stripping solution of the present invention, it is preferable that the dissolution rate of the resist film composed of the thermal reaction resist stripped by the resist stripping solution is 100 nm / min or more.

  The resist stripping solution of the present invention preferably contains no fluoride ions.

  In the resist stripping solution of the present invention, persulfuric acid, nitric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, aqua regia, trifluoroacetic acid, squaric acid, trifluoromethanesulfonic acid, carborane acid, It is preferable to include at least one selected from the group consisting of permanganic acid, chromic acid, fluoroacetic acid and salts of these acids.

  The resist stripping solution of the present invention preferably contains at least sulfuric acid.

  In the resist stripping solution of the present invention, it is preferable that silicon oxide is added to the thermal reaction type resist stripped by the resist stripping solution.

  In the resist stripping solution of the present invention, it is preferable that a fine pattern is imparted to the resist film composed of the thermal reaction type resist stripped by the resist stripping solution.

  The resist stripping method of the present invention uses the resist stripping solution having a pH of less than 0 with respect to a resist film formed on a substrate and composed of a heat-reactive resist mainly composed of copper oxide. It is characterized by peeling.

  In the resist stripping method of the present invention, the dissolution rate of the resist film is preferably 100 nm / min or more.

  In the resist stripping method of the present invention, the resist stripping solution preferably does not contain fluoride ions.

  In the resist stripping method of the present invention, the resist stripping solution contains persulfuric acid, nitric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, aqua regia, trifluoroacetic acid, squaric acid, trifluoromethane. It is preferable to include at least one selected from the group consisting of sulfonic acid, carborane acid, permanganic acid, chromic acid, fluoroacetic acid and salts of these acids.

  In the resist stripping method of the present invention, the resist stripping solution preferably contains at least sulfuric acid.

  In the resist stripping method of the present invention, it is preferable that silicon oxide is added to the thermal reaction resist stripped by the resist stripping solution.

  In the resist stripping method of the present invention, it is preferable that a fine pattern is provided on the resist film.

  According to the present invention, a resist film composed of a heat-reactive resist whose main component is copper oxide can be peeled off with high throughput without remaining.

It is the figure which showed intensity distribution of the laser beam. It is the figure which showed the temperature distribution of the part irradiated with the laser beam. It is a cross-sectional schematic diagram which shows the uneven structure of the fine pattern provided to the resist film which concerns on this Embodiment. It is a cross-sectional schematic diagram which shows the other example of the uneven structure of the fine pattern provided to the resist film which concerns on this Embodiment.

Hereinafter, embodiments of the present invention will be described in detail.
In the resist stripping solution according to the present embodiment, in order to remove the resist film composed of the heat-reactive resist together with the residual film near the substrate interface described above, the reactivity between the resist stripping solution and the resist film is used. Need to be high enough. As a method for dissolving a metal oxide such as copper oxide, there are mainly a method using a chelating agent and a method using an acid, and the method using an acid can make the reactivity higher. The stronger the acid, the higher the effect. In particular, the resist stripping solution according to the present embodiment has a pH of less than 0 because the removal performance of the residual film is stabilized by using what is generally called a strong acid. More preferably, the pH is −1 or less.

In addition, when a super strong acid is used, the amount of water is relatively reduced. As a result, although the acid is strong, the pH on the numerical value of a pH meter or the like may increase visually. The pH in the present application does not include such apparent pH. If it is difficult to measure an accurate pH such as a super strong acid, the pH may be calculated from Hammett acidity function. Hammett's acidity function (H ₀ ) is determined as follows. First, a weak acid having a higher proton donating ability than water, for example, acetic acid, is prepared, and each numerical value when a mixed state with a super strong acid or the like is made is defined as follows.
KBH ⁺ : ionization constant of weak acid in water CBH ⁺ : concentration of weak acid CB: concentration of anion in which proton is separated from weak acid At this time,
h ₀ = KBH ⁺ · (CBH ⁺ / CB)
Then, Hammett's acidity function is H ₀ = −log (h ₀ )

  As components of the resist stripping solution according to the present embodiment, persulfuric acid, nitric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, aqua regia, trifluoro, which can achieve a pH of less than 0. It is preferable to include at least one of acetic acid, squaric acid, trifluoromethanesulfonic acid, carborane acid, permanganic acid, chromic acid, fluoroacetic acid, hydrofluoric acid, and salts of these acids. Of these, persulfuric acid, nitric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, aqua regia, trifluoroacetic acid, squaric acid, trifluoromethanesulfonic acid, carborane acid, not containing fluoride ions It is more preferable to contain at least one of permanganic acid, chromic acid, fluoroacetic acid and salts of these acids.

  In addition, in view of the fact that the resist stripping solution component does not easily remain as a residue after drying, persulfuric acid, nitric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, trifluoroacetic acid, More preferably, at least one member selected from the group consisting of manganic acid, chromic acid, hydrofluoric acid, fluoroacetic acid and salts of these acids is included.

  These may be adjusted so as to satisfy the above pH condition alone, or may be adjusted so as to satisfy the above pH condition by mixing a plurality of types.

  In the resist stripping solution according to the present embodiment, when a strong acid having a pH of less than 0 is used, the dissolution rate of a resist film made of a heat-reactive resist mainly composed of copper oxide is 100 nm / min or more. . In order to further improve the throughput, it is preferable that the reactivity between the resist stripping solution and the resist film is high. From this viewpoint, the dissolution rate is preferably 100 nm / min or more, and more preferably the dissolution rate is 400 nm / min or more. More preferably, the dissolution rate is 1000 nm / min or more, even more preferably, the dissolution rate is 5000 nm / min or more, and most preferably the dissolution rate is 10,000 nm / min or more.

  In the present embodiment, the dissolution rate of the resist film is obtained, for example, by the following method. First, a resist film of a heat-reactive resist mainly composed of copper oxide is formed on a base material, and a part of the resist film is masked with a material that is not dissolved by a resist stripping solution. Next, a resist stripping solution is applied to the resist film, and the reaction is stopped by rinsing before unmasked portions are completely stripped. Finally, the mask is removed, and the film thickness (t1) where the film is peeled off with the resist stripping solution and the film thickness (t2) where the film is masked but not peeled are measured. -T1), and dividing this film thickness by the stripping time (the time from when the resist stripping solution is applied to the resist film until the reaction stops by immersing the resist film in a rinsing solution, etc.) Calculate the dissolution rate per hit. In addition, the method of measuring a film thickness includes a method of directly detecting a film thickness like a step meter, a method of calculating from a count number of elements using fluorescent X-rays, and the like. As for film thickness measurement, data accuracy may be increased by measuring a plurality of points.

  With respect to the resist stripping solution according to the present embodiment, it is important not only to remove the resist film but also to not damage the substrate on which the resist film is formed. For example, when glass is used for the base material on which the resist film is formed, if the resist stripping solution contains fluoride ions, the base material is also damaged. It is preferable to adjust the component and pH of the resist stripping solution in that the range of selection of the base material that is not damaged by the resist stripping solution, that is, the base material that can be used, can be made wider. From the above viewpoint, it is preferable to use a resist stripping solution that does not contain fluoride ions in that a glass-based material can be used for the substrate.

  As the heat-reactive resist, a resist mainly composed of copper oxide is used. For example, copper oxide or a material obtained by adding an additive to copper oxide can be used. Examples of the additive include Si, Al, Ni, Fe, Mo, Ti, Zr, In, Mn, Bi, Ta, Ga, Co, Pb, and oxides thereof. Moreover, it is preferable that it is 1 atomic%-40 atomic% as addition amount of an additive.

  In addition to the above, as a component of the resist stripping solution, an oxidizing agent or a surfactant that does not inhibit the resist stripping solution, or other additives as long as they do not damage the substrate may be added as appropriate.

  The oxidant may be appropriately selected from commonly used oxidants in consideration of the reactivity with the acid, etc. Specific examples include hydrogen peroxide, sodium permanganate, potassium permanganate, permanganate. Ammonium, calcium permanganate, magnesium permanganate, silver permanganate, barium permanganate, lithium chlorate, sodium chlorate, potassium chlorate, ammonium chlorate, lithium bromate, sodium bromate, potassium bromate, Ammonium bromate, lithium iodate, sodium iodate, potassium iodate, ammonium iodate, perchloric acid, lithium perchlorate, sodium perchlorate, potassium perchlorate, ammonium perchlorate, calcium perchlorate, perchlorate Silver chlorate, perbromate, lithium perbromate, sodium perbromate, perbromate , Ammonium perbromate, calcium perbromate, silver perbromate, periodic acid, lithium periodate, sodium periodate, potassium periodate, ammonium periodate, calcium periodate, silver periodate , Dichromic acid, lithium dichromate, sodium dichromate, potassium dichromate, calcium dichromate, magnesium dichromate, osmium tetroxide, metachloroperbenzoic acid, lithium persulfate, sodium persulfate, potassium persulfate And ammonium persulfate and iron chloride. Among these oxidants, hydrogen peroxide, potassium permanganate, lithium persulfate, sodium persulfate, potassium persulfate, ammonium persulfate, and iron chloride are preferable from the viewpoint of easy availability, safety, and environmental load. Most preferred are hydrogen peroxide, sodium persulfate, potassium persulfate, ammonium persulfate, and iron chloride. These oxidizing agents may be used alone or in combination of two or more.

  The surfactant may be selected in consideration of reactivity with acid among those improving wettability and permeability. A commercially available surfactant may be used as it is, or may be synthesized. The surfactant includes four types of anionic, cationic, nonionic and amphoteric. Of these, anionic, nonionic and amphoteric are preferable, and anionic and nonionic are particularly preferable. These surfactants may be used alone or in combination of two or more.

  Examples of the anionic surfactant include a carboxylic acid type, a sulfonic acid type, a sulfate ester type, and a phosphate ester type. Examples of the nonionic surfactant include a polyethylene glycol type, a polyalkylene glycol type, a polyhydric alcohol type, and an acetylene type. Specifically, examples of the anionic surfactant include olefin sulfonic acid, alkyl sulfonic acid, benzene sulfonic acid, alkyl sulfate ester, alkyl ether sulfate ester, alkyl carboxylic acid, perfluoroalkyl sulfonic acid, and salts thereof. Examples of nonionic surfactants include poly (oxyethylene) alkyl ether, poly (oxyethylene) fatty acid ester, polyethylene glycol, polyoxyethylene polyoxypropylene ether, glycerin fatty acid ester, acetylene diol, and acetylene glycol.

  The substrate for forming the resist film on which the resist stripping solution according to the present embodiment is applied is not particularly limited in shape, and may be a flat plate shape or a roll shape. As the material of the base material, a material that is not substantially damaged by the resist stripping solution is preferable. Examples of such a material include fluororesin, glass, silicon, silicon dioxide, and gold. Of these, fluororesin, glass, silicon, silicon dioxide and the like are preferable from the viewpoint of resistance to aqua regia. Further, a fluororesin is preferable from the viewpoint that the resist stripping solution does not receive damage even if it contains fluoride ions. Moreover, what formed the metal plating layer on the base member as a base material can also be used.

  From the viewpoint of a base material that is excellent in surface smoothness (a base material that is easy to polish) when forming a fine pattern with a heat-reactive resist that is peeled off with the resist stripping solution according to the present embodiment, glass and silicon are used. Preferably, glass, silicon, and silicon dioxide are preferable from the viewpoint of forming a fine pattern using a resist film and then subjecting the substrate to dry etching using the resist film as a mask. Glass and silicon are preferable from the viewpoint of excellent flatness and dry etching. In consideration of cost and availability (large-area substrate and roll substrate), glass is preferable, and quartz glass is most preferable.

  In the resist stripping method according to the present embodiment, a resist stripping solution having a pH of less than 0 is applied to a resist film formed on a base material and composed of a heat-reactive resist mainly composed of copper oxide. The resist film is peeled off.

  The method for causing the resist stripping solution to act on the resist film is not particularly limited, and the resist film may be immersed in the resist stripping solution, or the resist stripping solution may be sprayed onto the resist film. When the resist film is immersed in the resist stripping solution, the resist stripping solution is circulated while the substrate on which the resist film is formed is immersed in the resist stripping solution, or the substrate on which the resist film is formed is used as the resist stripping solution. It is also effective to move the substrate in the resist stripping solution while immersed.

  When spraying the resist stripping solution onto the resist film, if a method such as moving the nozzle that sprays the resist stripping solution or rotating the substrate on which the resist film is formed is used alone or in combination, the resist film is stripped. This is preferable because it proceeds uniformly. As the nozzle for spraying the resist stripping solution, any nozzle can be used, and examples thereof include a line slit nozzle, a full cone nozzle, a hollow cone nozzle, a flat nozzle, a uniform flat nozzle, and a solid nozzle. It can be selected according to the shape of the membrane or substrate. Further, when the resist stripping solution is sprayed onto the resist film, a plurality of nozzles may be used side by side, and a single fluid nozzle or a two fluid nozzle may be used.

  By controlling the temperature at which the resist stripping solution acts on the resist film, it is possible to change the stripping rate, the activity of the resist stripping solution, or the dissolution selectivity between the resist film and the substrate. The temperature can be arbitrarily set as long as the resist stripping solution is frozen or avoids a range that causes decomposition of the components in the resist stripping solution or the heat-reactive resist. For the above reasons, the temperature range is preferably 0 ° C. or more and 200 ° C. or less, more preferably the temperature range is 10 ° C. or more and 150 ° C. or less, and most preferably the temperature range is 10 ° C. or more and 120 ° C. or less, and is most preferable. The temperature range is 10 ° C. or more and 60 ° C. or less. In addition, considering the viewpoint that the resist stripping solution component is difficult to volatilize and is not easily altered (decomposition, oxidation, reduction, etc.), that is, resist stripping solution is not easily affected by the temperature and atmospheric conditions to be carried out, sulfuric acid, chromium Preferably, at least one selected from the group consisting of acids, trifluoroacetic acid, fluoroacetic acid and salts of these acids is included, and at least one selected from the group consisting of trifluoroacetic acid, fluoroacetic acid and salts of these acids is included. Most preferred.

  When impurities such as insoluble fine powder are present in the resist stripper when the resist stripper is applied to the resist film, there is a risk of pattern loss especially when a fine pattern is formed. It is preferable to filter the liquid in advance. The material of the filter used for filtration can be arbitrarily selected as long as it does not react with the resist stripping solution, and examples thereof include PFA and PTFE. The coarseness of the filter may be selected according to the fineness of the pattern, and is generally 0.2 μm or less, more preferably 0.1 μm or less. Also, in order to prevent precipitation and reattachment of the eluted components, it is preferable to spray the resist stripping solution onto the resist film rather than immersing the resist film in the resist stripping solution. More preferably, the resist stripping solution is not circulated and is made disposable.

  In the case where a fine pattern is given to the resist film that is the processing target of the resist stripping solution according to the present embodiment, the fine pattern is a resist film 12 provided on a substrate 11 as shown in FIG. The pitch of the concavo-convex structure formed in the above, that is, the pitch P between the adjacent convex portions 12a is a fine pattern of 1 nm or more and less than 5 μm. In addition, the pitch here does not necessarily need to be the pitch between the adjacent convex parts 12a of a concavo-convex structure, and may be the pitch between the adjacent concave parts 12b. The shape of the concavo-convex structure is not particularly limited, and examples thereof include a line and space shape, a dot shape, a long hole shape, and a mixed shape thereof. In addition, examples of the cross-sectional structure of the concavo-convex structure include a rectangular shape, a triangular shape, a dome shape, and a lens shape. The range of the fine pattern is preferably a fine pattern of 1 nm or more and less than 3 μm, more preferably 1 nm or more and less than 1 μm, and most preferably 10 nm or more and less than 800 nm.

  The addition of a fine pattern to the resist film means, for example, removing a part of the resist film formed on the base material to form a fine uneven structure on the resist film. More specifically, for example, a heat-reactive resist material mainly composed of copper oxide is formed on the main surface of the substrate, and then a part of the heat-reactive resist material is altered by heat by exposure. Subsequently, the development means removing either the altered portion or the unaltered portion to form a fine pattern on the substrate. The film formation is preferably sputter film formation from the viewpoint of uniformity, and the exposure is preferably performed using a semiconductor laser from the viewpoint of apparatus cost.

  Further, in FIG. 3, the case where the convex portions 12 a and the concave portions 12 b are formed in the resist film 12 has been described as an example, but the fine pattern uneven structure provided in the resist film according to the present embodiment is illustrated in FIG. As shown to 4A, the resist film 12 is patterned, the opening part 12c which exposes a part of base material 11 is formed, and the uneven structure is comprised by the surface of the base material 11 and the resist film 12 left on it. It is also included.

  Further, as shown in FIG. 4B, using the patterned resist film 12 as a mask, a part of the substrate 11 exposed in the opening 12c is etched to form a recess 11a, and the recess 11a of the substrate 11 is formed. And the case where the concavo-convex structure is constituted by the resist film 12 left on the substrate 11 is also included.

  The concavo-convex structure of the resist film 12 provided with the fine pattern is not particularly limited to the case described with reference to FIGS. 3 and 4, and the resist film is included in at least one of the convex portion or the concave portion constituting the concavo-convex structure. Needless to say, it is enough.

  Examples carried out to clarify the effects of the present invention will be described below, but the present invention is not limited by these examples. The following examples and comparative examples are collectively shown in Table 1 below.

Example 1
On a 50 mmφ glass substrate as a substrate, copper oxide added with Si as a heat-reactive resist was formed to a thickness of 20 nm by a sputtering method to form a resist film. Sputtering was performed under the following conditions.
Target: Copper (II) oxide added with Si (3 inch φ, copper oxide: Si = 85 atomic%: 15 atomic%)
Power (W): RF100
Gas type: Mixed gas of argon and oxygen (ratio 90:10)
Pressure (Pa): 0.5

Next, a part of the resist film was exposed under the following conditions so that a part that was altered by heat and a part that was not affected by heat were mixed.
Semiconductor laser wavelength for exposure: 405 nm
Lens numerical aperture: 0.85
Exposure laser power: 8.0mW
Feed pitch: 500nm

  Next, the resist film was stripped using a resist stripping solution prepared with 200 g of sulfuric acid and 100 g of 30% hydrogen peroxide water. Peeling was performed by immersing a substrate having a resist film in a resist stripping solution at 120 ° C. for 10 seconds. The dissolution rate of the heat-reactive resist in this resist stripping solution was 10000 nm / min by the above calculation method, and the pH of the resist stripping solution was measured with a pH meter. Due to the strong acid, accurate values could not be measured.

  When the substrate after resist peeling was measured by fluorescent X-ray, it was confirmed that the copper element did not remain in either the exposed portion or the unexposed portion on the substrate.

(Example 2)
On a 50 mmφ Teflon (registered trademark) substrate as a base material, copper oxide was deposited as a thermal reaction resist to a thickness of 40 nm by a sputtering method to form a resist film. Sputtering was performed under the following conditions.
Target: Copper (II) oxide (3 inches φ, copper oxide 100%)
Power (W): RF100
Gas type: Mixed gas of argon and oxygen (ratio 90:10)
Pressure (Pa): 0.5

Next, a part of the resist film was exposed under the following conditions so that a part that was altered by heat and a part that was not affected by heat were mixed.
Semiconductor laser wavelength for exposure: 405 nm
Lens numerical aperture: 0.85
Exposure laser power: 8.0mW
Feed pitch: 500nm

  Next, the resist film was stripped using a resist stripping solution prepared with 50 g of 60% nitric acid and 50 g of 47% hydrofluoric acid. Peeling was performed by immersing a substrate having a resist film in a resist stripping solution at 13 ° C. for 30 seconds. The dissolution rate of the heat-reactive resist in this resist stripping solution was 1000 nm / min by the above calculation method, and the pH of the resist stripping solution measured with a pH meter was -1.1.

  When the substrate after resist peeling was measured by fluorescent X-ray, it was confirmed that the copper element did not remain in either the exposed portion or the unexposed portion on the substrate.

Example 3
On a Teflon (registered trademark) roll having a length of 100 mm and 120 mmφ as a base material, copper oxide added with Si as a heat-reactive resist was formed to a thickness of 20 nm by a sputtering method to form a resist film. Sputtering was performed under the following conditions.
Target: Copper (II) oxide added with Si (3 inch φ, copper oxide: Si = 85 atomic%: 15 atomic%)
Power (W): RF100
Gas type: Mixed gas of argon and oxygen (ratio 90:10)
Pressure (Pa): 0.5

Next, a part of the resist film was exposed under the following conditions so that a part that was altered by heat and a part that was not affected by heat were mixed.
Semiconductor laser wavelength for exposure: 405 nm
Lens numerical aperture: 0.85
Exposure laser power: 8.0mW
Feed pitch: 500nm

  Next, the resist film was stripped using a resist stripping solution prepared with 30 g of 37% hydrochloric acid, 0.40 g of Adekatol SO-135 (manufactured by ADEKA, nonionic surfactant) and 90 g of water. Peeling was performed by spraying a resist stripping solution on the resist film at 33 ° C. for 30 seconds. The dissolution rate of the heat-reactive resist in this resist stripping solution was 500 nm / min by the above calculation method, and the pH of the resist stripping solution was measured with a pH meter, and was -0.5.

  When the base material after resist peeling was observed using an electron microscope, it was confirmed that the copper element did not remain in either the exposed part or the unexposed part on the base material.

(Comparative Example 1)
On a 50 mmφ glass substrate as a substrate, copper oxide added with Si as a heat-reactive resist was formed to a thickness of 20 nm by a sputtering method to form a resist film. Sputtering was performed under the following conditions.
Target: Copper (II) oxide added with Si (3 inch φ, copper oxide: Si = 85 atomic%: 15 atomic%)
Power (W): RF100
Gas type: Mixed gas of argon and oxygen (ratio 90:10)
Pressure (Pa): 0.5

Next, a part of the resist film was exposed under the following conditions so that a part that was altered by heat and a part that was not affected by heat were mixed.
Semiconductor laser wavelength for exposure: 405 nm
Lens numerical aperture: 0.85
Exposure laser power: 8.0mW
Feed pitch: 500nm

  Next, the resist film was stripped using a resist stripping solution prepared with 0.1 g of ammonium oxalate and 300 g of water. Peeling was performed by immersing a substrate having a resist film in a resist stripping solution at 23 ° C. for 10 minutes. The dissolution rate of the heat-reactive resist in this resist stripping solution was 2 nm / min by the above calculation method, and the pH of the resist stripping solution was 6.4.

  When the base material after resist peeling was observed using an electron microscope, the color derived from copper oxide was confirmed. Moreover, when it measured with the fluorescent X ray about the base material after resist peeling, it was confirmed that the copper element remains.

  Furthermore, when the substrate was immersed in the resist stripper and the stripping process was extended for 20 minutes, the color derived from copper oxide disappeared visually, but when the fluorescent X-rays of the substrate were measured, the substrate was exposed. It was confirmed that the copper element remained in the part, and it was found that the peeling was not completed.

Example 4
On a 50 mmφ quartz substrate as a base material, copper oxide added with Si as a thermal reaction resist was formed to a thickness of 20 nm by a sputtering method to form a resist film. Sputtering was performed under the following conditions.
Target: Copper (II) oxide added with Si (3 inch φ, copper oxide: Si = 85 atomic%: 15 atomic%)
Power (W): RF100
Gas type: Mixed gas of argon and oxygen (ratio 90:10)
Pressure (Pa): 0.5

Next, a part of the resist film was exposed under the following conditions so that a part that was altered by heat and a part that was not affected by heat were mixed.
Semiconductor laser wavelength for exposure: 405 nm
Lens numerical aperture: 0.85
Exposure laser power: 8.0mW
Feed pitch: 500nm

  Next, trifluoroacetic acid and (mono) fluoroacetic acid were prepared as resist stripping solutions, and the resist film was stripped. Peeling was performed by immersing a substrate having a resist film in a resist stripping solution at 23 ° C. for 3 minutes. The dissolution rate of the heat-reactive resist in this resist stripping solution was 14000 nm / min and 12000 nm / min, respectively, according to the above calculation method, which were very fast stripping rates.

  When the pH of the resist stripping solution was measured with a pH meter, the numerical values were -1.5 and -1.0, respectively, but due to the super strong acid, an accurate numerical value could not be measured.

  When the substrate after resist peeling was measured by fluorescent X-ray, it was confirmed that the copper element did not remain in either the exposed portion or the unexposed portion on the substrate.

  As described above, in Examples 1 to 4, since the resist stripping solution having a pH of less than 0 was used, the heat-reactive resist mainly composed of copper oxide could be stripped without a residual film. However, in Comparative Example 1, since a resist stripping solution having a pH of 0 or more was used, it was not possible to strip the heat-reactive resist mainly composed of copper oxide without a residual film.

  The present invention is not limited to the embodiment described above, and can be implemented with various modifications. For example, the materials, shapes, and the like of the members in the above-described embodiments are exemplary, and can be appropriately changed and implemented within a range that exhibits the effects of the present invention. In addition, various modifications can be made without departing from the scope of the present invention.

  The resist stripping solution according to the present invention is effective for stripping a resist film composed of a heat-reactive resist mainly composed of copper oxide, and can be used for pattern formation using the resist. .

11 Substrate 11a Concave 12 Resist Film 12a Convex 12b Concave 12c Opening

Claims (14)

  A resist stripping solution for a heat-reactive resist containing copper oxide as a main component, wherein the resist stripping solution has a pH of less than 0.   2. The resist stripping solution according to claim 1, wherein a dissolution rate of the resist film composed of the thermal reaction resist stripped by the resist stripping solution is 100 nm / min or more.   The resist stripping solution according to claim 1 or 2, which does not contain fluoride ions.   Persulfuric acid, nitric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, aqua regia, trifluoroacetic acid, squaric acid, trifluoromethanesulfonic acid, carborane acid, permanganic acid, chromic acid, fluoroacetic acid And at least one selected from the group consisting of these acid salts. 4. The resist stripping solution according to claim 1, comprising:   The resist stripping solution according to claim 1, comprising at least sulfuric acid.   The resist stripping solution according to any one of claims 1 to 5, wherein silicon oxide is added to the thermal reaction resist stripped by the resist stripping solution.   The resist stripping solution according to any one of claims 1 to 6, wherein a fine pattern is given to a resist film composed of the thermal reaction resist stripped by the resist stripping solution.   The resist film is stripped using a resist stripping solution having a pH of less than 0 with respect to a resist film formed of a heat-reactive resist mainly composed of copper oxide formed on a substrate. Resist stripping method.   9. The resist stripping method according to claim 8, wherein the dissolution rate of the resist film is 100 nm / min or more.   The resist stripping method according to claim 8 or 9, wherein the resist stripper does not contain fluoride ions.   The resist stripping solution is persulfuric acid, nitric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, aqua regia, trifluoroacetic acid, squaric acid, trifluoromethanesulfonic acid, carborane acid, permanganic acid The resist stripping method according to claim 8, comprising at least one selected from the group consisting of chromic acid, fluoroacetic acid, and salts of these acids.   The resist stripping method according to any one of claims 8 to 11, wherein the resist stripper contains at least sulfuric acid.   The resist stripping method according to any one of claims 8 to 12, wherein silicon oxide is added to the thermal reaction resist stripped by the resist stripping solution.   The resist stripping method according to claim 8, wherein a fine pattern is provided on the resist film.

Images