JP5262478B2 - Etching solution for transparent electrodes - Google Patents

Description

  The present invention relates to an etching solution for transparent electrodes.

  Transparent electrodes are indispensable for the production of flat panel displays, solar cells and the like.

  Such a transparent electrode is formed by applying a photoresist on a transparent conductive film such as an ITO (indium-tin oxide) film or an IZO (indium-zinc oxide) film, exposing and developing, and then etching using the photoresist as a mask. After etching using a liquid, the remaining photoresist is peeled off. Since ITO and IZO are very expensive, various new transparent electrodes have been proposed. Among them, a ZAO (aluminum oxide-added zinc oxide) film has been attracting attention because of its low resistance.

  Various etching solutions for transparent electrodes mainly composed of ITO (ITO transparent electrodes) and transparent electrodes mainly composed of IZO (IZO transparent electrodes) have been proposed (see, for example, Patent Document 1 and Patent Document 2). In addition, as an etching solution for a transparent electrode mainly containing ZAO (ZAO transparent electrode), an etching solution mainly containing citric acid has been proposed (see, for example, Patent Document 3).

  Since the ITO transparent electrode and the IZO transparent electrode are high-performance but expensive transparent electrodes, ITO (or IZO) and ZAO may be used together for the purpose of cost reduction. In this case, it is necessary to etch ZAO with the same etchant as ITO (or IZO). In general, ZAO is more soluble in acid than ITO (or IZO). For example, when an etching solution for ITO (or IZO) such as a mixture of phosphoric acid, nitric acid and acetic acid is used, ZAO is 100 times faster than ZOO. Etching cannot be controlled because of etching.

  Therefore, in order to etch a transparent electrode using both ITO (or IZO) and ZAO, the etching rate difference between ZAO and ITO (or IZO) must be reduced. Therefore, it has been desired to develop an etching solution that can etch ZAO and ITO (or IZO) with the same solution.

JP 2000-149678 A JP 2003-306676 A JP 2008-047645 A

  This invention is made | formed in view of said subject, The 1st objective is to provide the etching liquid of a ZAO transparent electrode. The second object is to provide an etching solution that can etch the ITO transparent electrode (or IZO transparent electrode) and the ZAO transparent electrode with the same solution.

  As a result of intensive studies on etching of ZAO transparent electrodes, the present inventors have found that one or more compounds selected from the group consisting of hydrobromic acid and its salt, and a group consisting of hydrofluoric acid and its salt. It has been found that an aqueous solution containing one or two or more selected compounds can etch a ZAO transparent electrode, and can etch an ITO transparent electrode (or an IZO transparent electrode) and a ZAO transparent electrode with the same liquid. It came to complete.

  That is, this invention is an etching liquid for transparent electrodes as shown below, and an etching method using the same.

  [1] From an aqueous solution containing one or more compounds selected from the group consisting of hydrobromic acid and salts thereof, and one or more compounds selected from the group consisting of hydrofluoric acid and salts thereof An etching solution for transparent electrodes.

  [2] The etching solution according to the above [1], wherein the salt of hydrobromic acid is one or more compounds selected from the group consisting of ammonium hydrobromide and an amine salt of hydrobromic acid.

  [3] The etching solution according to [1] or [2], wherein the salt of hydrofluoric acid is one or two or more compounds selected from the group consisting of ammonium fluoride and an amine salt of hydrofluoric acid. .

  [4] The group consisting of hydrofluoric acid and its salt in the range of 0.01 to 10% by weight of one or more compounds selected from the group consisting of hydrobromic acid and its salt with respect to the whole etching solution Etching liquid in any one of said [1] thru | or [3] in which the 1 type or 2 or more types of compound chosen from more is contained in 0.01 to 10 weight%.

  [5] A method for etching a transparent electrode, comprising etching a transparent electrode containing zinc oxide and aluminum oxide as main components using the etching solution according to any one of [1] to [4].

  [6] Etching a transparent electrode mainly composed of zinc oxide and aluminum oxide and a transparent electrode mainly composed of indium with the same liquid using the etching liquid according to any one of [1] to [4] above. A method for etching a transparent electrode.

  [7] The etching method according to [5] or [6], wherein the transparent electrode mainly composed of zinc oxide and aluminum oxide is a transparent electrode mainly composed of ZAO (aluminum oxide-added zinc oxide).

  [8] The above [5] to [7], wherein the transparent electrode mainly composed of indium is a transparent electrode mainly composed of ITO (indium-tin oxide) or IZO (indium-zinc oxide). The etching method as described.

  According to the etching solution of the present invention, the ITO transparent electrode (or IZO transparent electrode) and the ZAO transparent electrode can be etched with the same solution, which is extremely useful industrially.

  The essential components of the etching solution of the present invention are one or more compounds selected from the group consisting of hydrobromic acid and salts thereof, and one or more compounds selected from the group consisting of hydrofluoric acid and salts thereof. It is a compound of this.

  In the etching solution of the present invention, hydrobromic acid and hydrobromide have the effect of increasing the etching rate of ZAO, ITO and IZO.

  There is no restriction | limiting in particular in the hydrobromic acid and hydrobromide which can be used for the etching liquid of this invention. For example, as a hydrobromide, an ammonium salt and an amine salt of hydrobromic acid are preferable. In the present invention, it is possible to etch a transparent electrode even if a metal salt such as sodium salt or potassium salt of hydrobromic acid is used. However, in the production of a general flat panel display, metal is disliked. It is preferable to use an ammonium salt or amine salt of an acid. Further, when hydrobromic acid and hydrobromide are used in combination, an etching solution having a small pH variation and having no damage to other materials constituting the flat panel display can be obtained.

  In the etching solution of the present invention, hydrofluoric acid or a salt thereof (that is, fluoride salt) has an effect of increasing the etching rate of ITO (or IZO) and decreasing the etching rate of ZAO.

  There is no restriction | limiting in particular in the hydrofluoric acid and / or fluoride salt which can be used for the etching liquid of this invention. In the present invention, even if a metal salt such as sodium fluoride or potassium fluoride is used as the fluoride salt, the transparent electrode can be etched, but the production of a general flat panel display dislikes the metal as described above. Therefore, it is preferable to use an ammonium salt of hydrofluoric acid (that is, ammonium fluoride) or an amine salt.

  In the etching solution of the present invention, one or more compounds selected from the group consisting of hydrobromic acid and salts thereof, and one or more compounds selected from the group consisting of hydrofluoric acid and salts thereof are: Used by dissolving in water or suspending.

  In the etching solution of the present invention, a hydrophilic organic solvent such as alcohol may be added. Examples of such organic solvents include alcohols such as methanol, ethanol and propanol, ketones such as acetone and methyl ethyl ketone, sulfoxides such as dimethyl sulfoxide, amides such as N, N-dimethylformamide and N-methylpyrrolidone, and γ-butyrolactone. Examples include lactones.

  The etching solution of the present invention is usually in the range of 0.01 to 10% by weight of one or two or more compounds selected from the group consisting of hydrobromic acid and salts thereof with respect to the whole etching solution, hydrofluoric acid And one or more compounds selected from the group consisting of salts thereof and 0.01 to 10% by weight. Preferably, one or two or more compounds selected from the group consisting of hydrobromic acid and salts thereof are in the range of 0.1 to 5% by weight, one or two selected from the group consisting of hydrofluoric acid and salts thereof. More than one compound is included in the range of 0.01 to 5% by weight. If the amount of one or two or more compounds selected from the group consisting of hydrobromic acid and its salt is less than the above range, the etching power may decrease unindustrially. There is a risk that it becomes too controllable. Further, if the amount of one or more compounds selected from the group consisting of hydrofluoric acid and its salt is less than the above range, the etching rate of ITO (or IZO) may be reduced, and if it exceeds the above range, it is There is a possibility that damage to other materials constituting the panel display may increase.

  The etching solution of the present invention etches transparent electrodes (ie, ZAO transparent electrodes, ITO transparent electrodes, IZO transparent electrodes, etc.) mainly composed of ZAO, ITO, IZO, etc. in the manufacturing process of flat panel displays, solar cells, etc. It is used as an etchant for

  The etching solution of the present invention can etch the ITO transparent electrode (or IZO transparent electrode) and the ZAO transparent electrode with the same solution.

  Since the etching solution of the present invention has very high etching performance, it can be used sufficiently even at low temperatures, but the use temperature is preferably in the range of 0 to 100 ° C. If it is less than 0 ° C., the etching rate is unrealistically slow, and if it exceeds 100 ° C., water transpiration and evaporation become severe, which is not practical.

  The etching solution of the present invention can be used without any problem in either batch type or single wafer type, and cleaning by spraying or other methods may be used. Furthermore, ultrasonic waves can be used in combination as necessary. As the rinsing after etching, it is not necessary to use an organic solvent such as alcohol, and it is sufficient to rinse with water.

  The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In order to simplify the notation, the following abbreviations were used.

ZAO: zinc oxide added with aluminum oxide ITO: indium-tin oxide HBr: hydrobromic acid AF: ammonium fluoride Examples 1-6, Comparative Examples 1-3:
A substrate on which a ZAO film was formed with a thickness of 100 nm on a glass plate and a substrate on which an ITO film was formed with a thickness of 100 nm on a glass plate were immersed in the etching solution shown in Table 1, washed with water and dried, and then its sheet resistance Each film thickness was measured. The etching rate of ZAO and ITO was calculated from the change in film thickness before and after immersion. The results are shown in Table 1.

表１から明らかなとおり、本発明のエッチング液は、ＩＴＯとＺＡＯを同一液でエッチングできる。

As is apparent from Table 1, the etching solution of the present invention can etch ITO and ZAO with the same solution.

Claims (7)

A transparent electrode mainly composed of zinc oxide and aluminum oxide, one or more compounds selected from the group consisting of hydrobromic acid and salts thereof, and one type selected from the group consisting of hydrofluoric acid and salts thereof Or the etching method of the transparent electrode etched using the etching liquid for transparent electrodes which consists of an aqueous solution containing a 2 or more types of compound. The method according to claim 1, wherein the salt of hydrobromic acid is one or two or more compounds selected from the group consisting of ammonium hydrobromide and an amine salt of hydrobromic acid. The method according to claim 1 or 2, wherein the hydrofluoric acid salt is one or more compounds selected from the group consisting of ammonium fluoride and an amine salt of hydrofluoric acid. A transparent electrode composed mainly of zinc oxide and aluminum oxide and a transparent electrode composed mainly of indium, one or more compounds selected from the group consisting of hydrobromic acid and salts thereof, and hydrofluoric acid And the etching method of the transparent electrode which etches with the same liquid using the etching liquid for transparent electrodes which consists of the aqueous solution containing the 1 type, or 2 or more types of compound chosen from the group which consists of the salt . The method according to claim 4, wherein the salt of hydrobromic acid is one or more compounds selected from the group consisting of ammonium hydrobromide and an amine salt of hydrobromic acid. The method according to claim 4 or 5, wherein the hydrofluoric acid salt is one or more compounds selected from the group consisting of ammonium fluoride and an amine salt of hydrofluoric acid. The method according to claim 1 , wherein the transparent electrode mainly composed of zinc oxide and aluminum oxide is a transparent electrode mainly composed of ZAO (aluminum oxide added zinc oxide). .