TWI604090B - Etching method - Google Patents

Description

Etching method

The present invention relates to an etchant for etching a processed object in which a metal oxide layer and a copper layer are simultaneously present, and an etching method of selectively etching the copper layer and an etching method using the foregoing etchant.

Conventionally, a conductive metal oxide layer composed of indium tin oxide (ITO) or indium zinc oxide (IZO) has a low electrical resistance and exhibits high transmittance. Therefore, it is widely used as a transparent conductor. In addition, a metal oxide semiconductor layer made of IGZO or the like such as In-Ga-ZnO4 or In2-Ga2-ZnO7 has been studied and applied to various devices such as electronic paper. When such a metal oxide is applied to various devices, it is usually used in a form in which it coexists with a metal layer patterned into an electrode shape or the like.

As a method of processing a form in which a metal oxide layer and a patterned metal layer are simultaneously present, there is known a method of preparing a workpiece on which a metal oxide layer is laminated on a metal layer or an upper layer of a metal oxide layer. a workpiece in which a metal layer is formed, or a workpiece in which a metal oxide layer is provided adjacent to a metal oxide layer, and a metal oxide layer and a metal layer are simultaneously processed, and the metal layer is selectively etched using an etchant. .

For example, Patent Document 1 listed below discloses a method of producing a liquid crystal element in which an ITO layer and a patterned aluminum layer are simultaneously present, using a mixed acid including phosphoric acid, acetic acid, and nitric acid as an etchant for an aluminum layer.

[Previous Technical Literature]

[Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. Hei 10-96937

In recent years, in particular, electrode wiring in the field of displays tends to use fine wiring due to requirements for large screen and high definition, and it is desired to obtain an electrode having a lower electric resistance than an aluminum electrode. Therefore, the use of a copper electrode instead of an aluminum electrode is being studied. However, for the prior copper etchant, the etchant composition which can selectively etch the copper layer from the workpiece (the processed object) in which the metal oxide layer and the copper layer are simultaneously present is not sufficiently studied. In particular, a transparent metal oxide layer such as an ITO layer used for a touch panel is continuously developed due to high definition, and if the transparent metal oxide layer is etched by an etchant of a copper layer, it will become a fatal defect. Therefore, it is desirable to obtain an etchant that can selectively etch only a copper layer without etching the metal oxide layer.

The present invention has been made in view of the above circumstances, and provides an etching agent for selectively etching a copper layer and a copper layer, and an etching method capable of selectively etching the copper layer and an etching method using the etching agent.

In order to achieve the above object, the present invention is an etchant for etching a processed object in which a metal oxide layer and a copper layer are simultaneously present, and selectively etching the copper layer, the metal oxide layer being selected from the group consisting of Zn, An oxide of one or more metals of Sn, Al, In, and Ga, the etchant It is characterized in that it comprises 0.1 to 3.0% by weight of a copper (II) ion source in terms of copper ions; 0.1 to 30.0% by weight of an organic acid having a carbon number of 6 or less; and 0.1 to 30.0% by weight of a nitrogen-containing compound. In the aqueous solution, the nitrogen-containing compound is one or more selected from the group consisting of a heterocyclic compound having two or more nitrogen atoms in the ring and an amino group-containing compound having a carbon number of 8 or less, and has a pH of 5.0 to 10.5.

Further, in the etching method of the present invention, the object to be treated is selectively etched using an etchant to selectively treat the copper layer, wherein the metal oxide layer is selected from the group consisting of Zn, An oxide of one or more metals of Sn, Al, In, and Ga, characterized in that the etchant is the etchant of the present invention described above.

Further, in the above-described etchant and etching method of the present invention, the "copper layer" may be composed of copper or a copper alloy. Further, "copper" in the present specification means copper or a copper alloy.

If the etchant and the etching method of the present invention are used, when the metal oxide layer and the copper layer are simultaneously processed while etching, the copper layer can be selectively etched only. Thereby, for example, in the case of manufacturing a device in which a metal oxide layer and a patterned metal layer are simultaneously present, the yield can be improved and the manufacturing cost can be reduced.

The etchant of the present invention is an etchant for etching an object to be simultaneously etched with a metal oxide layer and a copper layer, and the metal oxide layer is selected from the group consisting of Zn, Sn. An oxide of one or more metals of Al, In, and Ga. The metal oxide constituting the metal oxide layer may be a single metal oxide or a composite metal oxide, and examples thereof include ZnO, SnO ₂ , Al ₂ O ₃ , indium tin oxide (ITO), and indium oxide. IGZO or the like such as zinc (IZO), In-Ga-ZnO ₄ or In ₂ -Ga ₂ -ZnO ₇ . From the viewpoint of preventing etching of the metal oxide layer when etching the copper layer, a metal oxide layer containing an oxide of one or more metals selected from the group consisting of Zn, Sn, and Al is preferable, and more preferably contains a metal oxide layer selected from the group consisting of ZnO, A metal oxide layer of one or more metal oxides of SnO ₂ , Al ₂ O ₃ , ITO, IZO, and IGZO.

(copper (II) ion source)

In the etchant of the present invention, the copper (II) ion source is a component that functions as an oxidizing agent for copper. Examples of the copper (II) ion source include a copper complex of the following nitrogen-containing compound, copper hydroxide, a copper complex of the following organic acid, copper carbonate, copper sulfate, copper oxide, or copper chloride; Or a copper halide such as copper bromide. In the present invention, one or a combination of them may be used in combination. Among them, copper formate, copper acetate, copper chloride, and copper bromide are preferred from the viewpoint of improving the etching rate.

The content of the copper (II) ion source is from 0.1 to 3.0% by weight, preferably from 0.25 to 2.5% by weight, more preferably from 0.5 to 2.0% by weight, based on the copper ion, from the viewpoint of increasing the etching rate.

(organic acid having a carbon number of 6 or less)

In the etchant of the present invention, an organic acid having a carbon number of 6 or less is formulated. As a component that dissolves oxidized copper. The carbon number of the organic acid is preferably from 1 to 5, more preferably from 1 to 4, from the viewpoint of improving the solubility of copper. Further, the aforementioned organic acid may be separately formulated into the etchant or may be formulated into the etchant in the form of a copper complex.

The organic acid may, for example, be an aliphatic carboxylic acid or an aromatic carboxylic acid. Specific examples of the aliphatic carboxylic acid include aliphatic saturated monocarboxylic acids such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, and caproic acid; and aliphatic unsaturated monocarboxylic acids such as acrylic acid, crotonic acid, and isocrotonic acid. Acid; aliphatic saturated dicarboxylic acid such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid and pimelic acid; aliphatic unsaturated dicarboxylic acid such as maleic acid; glycolic acid, A hydroxycarboxylic acid such as lactic acid, malic acid or citric acid; a carboxylic acid having a substituent such as sulfamic acid, β-chloropropionic acid, nicotinic acid, ascorbic acid, hydroxypivalic acid or acetyl propionic acid; and a derivative thereof. In the present invention, one or a combination of them may be used in combination. Among them, an aliphatic saturated monocarboxylic acid, an aliphatic saturated dicarboxylic acid, a hydroxycarboxylic acid is preferred, from the viewpoint of not inhibiting the oxidation of copper and causing no increase in the viscosity of the etchant. It is formic acid, acetic acid, propionic acid, butyric acid, capric acid, oxalic acid, lactic acid, malic acid and citric acid.

The content of the organic acid is from 0.1 to 30.0% by weight, preferably from 0.5 to 20.0% by weight, more preferably from 1.0 to 10.0% by weight. If the content of the aforementioned organic acid is 0.1% by weight or more, the solubility of copper oxide will increase. In addition, when the content of the organic acid is 30.0% by weight or less, the dissolution stability of copper can be suppressed from being lowered, and precipitation of organic acid crystals can be prevented.

(nitrogen-containing compounds)

In the etchant of the present invention, one or more nitrogen-containing compounds selected from the group consisting of a heterocyclic compound having two or more nitrogen atoms in the ring and an amine group-containing compound having a carbon number of 8 or less are used. The dissolved copper is formulated in the form of a complex as a component held in the etchant. In the present invention, one or more nitrogen-containing compounds may be used. Further, the nitrogen-containing compound may be formulated into the etchant alone or in the form of a copper complex. Further, the aforementioned nitrogen-containing compound does not include the aforementioned organic acid.

The heterocyclic compound is not particularly limited as long as it has two or more nitrogen atoms in the ring, and examples thereof include azoles such as imidazoles, pyrazoles, triazoles, tetrazoles, and derivatives thereof. From the viewpoint of the mismatch between the copper and the dissolved copper, an imidazole such as imidazole or benzimidazole or a pyrazole such as pyrazole is preferred. Specific examples thereof include imidazole, 2-methylimidazole, 1,2-diethylimidazole, benzimidazole, pyrazole, triazole, and benzotriazole, among which imidazole and 2-methylimidazole are preferred. , 2-diethylimidazole, benzimidazole and pyrazole.

The amino group-containing compound is not particularly limited as long as it has a carbon number of 8 or less. From the viewpoint of the compatibility with the dissolved copper, the carbon number is preferably 0 to 7, more preferably the number of carbon atoms. It is 0~5.

The amine group-containing compound may, for example, be ammonia; an alkylamine such as methylamine, dimethylamine or trimethylamine; an alkanolamine; an aromatic amine such as aniline or the like. Further, an amine compound containing two or more amine groups such as ethylenediamine or a quaternary amine compound such as tetramethylammonium may also be used. Among them, ammonia and an alkanolamine are preferred from the viewpoint of mismatching with dissolved copper.

Specific examples of the aforementioned alkanolamines include, for example, monoethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine And monoethanolamine such as 2-(2-hydroxy)ethoxyethanolamine and derivatives thereof; diethanolamine such as diethanolamine, N-methyldiethanolamine and N-butyldiethanolamine and derivatives thereof; triethanolamine; propanolamine ; isopropanolamine; hydroxyethylpiperazine; and derivatives thereof. Among them, monoethanolamine, diethanolamine and triethanolamine are preferred from the viewpoint of the compatibility with the dissolved copper.

From the viewpoint of the mismatch between the copper and the dissolved copper, the nitrogen-containing compound is preferably an imidazole, a pyrazole, an ammonia or an alkanolamine, more preferably an imidazole or a 2-methylimidazole, and 1,2. -diethylimidazole, benzimidazole, pyrazole, ammonia, monoethanolamine, diethanolamine and triethanolamine.

The content of the nitrogen-containing compound is from 0.1 to 30.0% by weight, preferably from 1.0 to 25.0% by weight, more preferably from 10.0 to 20.0% by weight. If the content of the aforementioned nitrogen-containing compound is 0.1% by weight or more, the etching rate can be increased. Further, when the content of the nitrogen-containing compound is 30.0% by weight or less, the increase in the viscosity of the etchant can be suppressed.

(other additives)

In order to improve the solubility and dissolution stability of copper and to increase the etching rate, a source of a halogen ion may also be formulated in the etchant of the present invention. Specific examples of the source of the halogen ion include inorganic acids such as hydrochloric acid, hydrobromic acid, and hydroiodic acid; copper chloride, copper bromide, iron chloride, sodium chloride, sodium iodide, ammonium chloride, and the like. Inorganic salt. In addition, in order to perform uniform etching, the etchant of the present invention may also be formulated with polyalkylene glycol or polyalkylene glycol derivative. Surfactants such as substances. The content of these additives in the etchant is about 0.01 to 10% by weight.

The pH of the etchant of the present invention is from 5.0 to 10.5, preferably from 5.0 to 10.0, more preferably from 5.0 to 7.0, from the viewpoint of preventing etching of the metal oxide layer when etching the copper layer. In particular, from the viewpoint of preventing the etching of the metal oxide layer containing a metal oxide of an amphoteric metal such as Zn, Sn or Al, the pH of the etchant is preferably 5.0 to 7.0. Further, the pH of the etchant can be controlled by adjusting the contents of the aforementioned organic acid and the aforementioned nitrogen-containing compound.

The etchant of the present invention can be easily formulated by dissolving the above components in water. The water is preferably deionized water. Further, in the etchant of the present invention, the above components may be formulated to have a specific concentration at the time of use, or a concentrate may be prepared in advance, and the concentrate may be diluted and used immediately before use.

The method of using the etchant of the present invention is not particularly limited, and examples thereof include a method of spraying an etchant on a workpiece on which a metal oxide layer and a copper layer are simultaneously present, and immersing the workpiece in an etchant. Method, etc. When the immersion method is used, the copper (I) ions generated in the etchant are oxidized to copper (II) ions by etching of copper, and therefore air may be blown by bubbles or the like. When the etching treatment is performed, the temperature of the etchant is preferably 10 to 50 ° C, and the treatment time is preferably 10 to 120 seconds.

The etchant of the present invention is suitable for use in the fabrication of devices in which a metal oxide layer and a patterned metal layer are present at the same time. Examples of the element include a liquid crystal element, an organic EL element, a touch panel, an electronic paper, and a photoelectric conversion element.

[Examples]

Hereinafter, examples of the etchant of the present invention will be described with reference to comparative examples. In addition, the present invention is not construed as being limited to the following embodiments.

(etching speed of copper layer)

A copper-clad laminate (product name: glass epoxy multilayer board R-1766) manufactured by Panasonic Electric Works Co., Ltd. having a thickness of 1.6 mm was immersed in an etching solution (200 g/L of sulfuric acid). In the case of 50 g/L of hydrogen peroxide and the remainder being deionized water, the copper foil of the laminate was completely removed, and an electroless plating solution manufactured by Okuno Chemical Industries Co., Ltd. was used (product name: OPC COPPER H) An electroless plating having a thickness of about 1.5 μm was completely applied to one side of the exposed glass epoxy substrate, and cut into 50 mm × 50 mm to serve as a test substrate. The substrate was etched by a spray treatment (spray pressure: 0.05 MPa) for 30 seconds using each of the etchants (temperature: 30 ° C) described in Table 1. Then, the etching rate was calculated from the weight of the test substrate before and after the treatment according to the following formula. The results are shown in Table 2. In addition, "unable to measure" in Table 2 means that the weight of the test substrate did not change even if the etching process was performed for 30 seconds.

Etching rate (μm/min) = [weight before treatment (g) - weight after treatment (g)] ÷ substrate area (m2) ÷ 8.92 (g/cm3) ÷ processing time (minutes)

(etching speed of ITO layer and IGZO layer)

A substrate having an ITO film or an IGZO film having a thickness of 0.2 μm formed on a float glass substrate (manufactured by Asahi Glass Co., Ltd.) of 100 mm × 100 mm and a thickness of 2 mm by a spray method was used as a substrate. Test the substrate. These test substrates were etched by a spray treatment (spray pressure: 0.1 MPa) using each of the etchants (temperature: 30 ° C) described in Table 1, and the surface treated every 30 seconds was measured by XPS. Then, from the time when the peak of In of one of the constituent components disappears, the etching rate is calculated according to the following formula. The results are shown in Table 2. In addition, "unable to measure" in Table 2 means that the peak of In does not change even if the etching process is performed for 10 minutes.

Etching rate (μm/min) = 0.2 μm ÷ [processing time (minutes) until the peak of In disappears].

As shown in Table 2, according to the embodiment of the present invention, the difference between the etching rate of the copper layer and the etching rate of the ITO layer or the IGZO layer can be expanded as compared with the comparative example. From this result, it was confirmed that, according to the present invention, it is possible to selectively etch only the copper layer from the object to be treated in which the metal oxide layer and the copper layer are simultaneously present.

Claims (3)

An etching method is an etchant for treating a material to be treated with a metal oxide layer and a copper layer, thereby selectively etching the copper layer, wherein the metal oxide layer is selected from the group consisting of Zn, Sn, and Al. An oxide of one or more metals in In and Ga; the etchant is an organic material comprising a copper (II) ion source in an amount of 0.1 to 3.0% by weight based on copper ions, and a carbon number of 6 to 30.0% by weight or less An acid and an aqueous solution of 0.1 to 30.0% by weight of a nitrogen-containing compound selected from the group consisting of a heterocyclic compound having two or more nitrogen atoms in the ring and an amine-containing compound having a carbon number of 8 or less. One or more of the groups are formed; the pH of the etchant is 5.0 to 10.5. The etching method according to claim 1, wherein the organic acid is one or more selected from the group consisting of aliphatic saturated monocarboxylic acids, aliphatic saturated dicarboxylic acids, and hydroxycarboxylic acids. The etching method according to claim 1 or 2, wherein the nitrogen-containing compound is one or more selected from the group consisting of imidazoles, pyrazoles, ammonia, and alkaneamines.