Etching liquid and etching method

Abstract

An object of the present invention is to provide: an etching liquid which is capable of etching titanium selectively in the presence of copper, and is further low in toxicity and excellent in storage stability; and an etching method using this etching liquid. The etching liquid of the present invention which is a liquid includes at least one acid selected from the group consisting of sulfuric acid, hydrochloric acid, and trichloroacetic acid, and at least one organic sulfur compound selected from the group consisting of a thioketone compound and a thioether compound, and makes it possible to etch titanium selectively in the presence of copper.

1 . An etching liquid for etching titanium selectively in the presence of copper, comprising:
 at least one acid selected from the group consisting of sulfuric acid, hydrochloric acid, and trichloroacetic acid; and   at least one organic sulfur compound selected from the group consisting of a thioketone compound and a thioether compound.   
     
     
         2 . The etching liquid according to  claim 1 , wherein the thioketone compound is at least one selected from the group consisting of thiourea, diethylthiourea, and trimethylthiourea. 
     
     
         3 . The etching liquid according to  claim 1 , wherein the thioether compound is at least one selected from the group consisting of methionine, ethionine, and 3-(methylthio) propionic acid. 
     
     
         4 . The etching liquid according to  claim 1 , further comprising an α-hydroxycarboxylic acid, and/or a salt thereof. 
     
     
         5 . The etching liquid according to  claim 4 , wherein the α-hydroxycarboxylic acid is at least one selected from the group consisting of tartaric acid, malic acid, citric acid, lactic acid, and glyceric acid. 
     
     
         6 . The etching liquid according to  claim 1 , wherein the concentration of the acid(s) is from 20 to 70% by weight, and
 the concentration of the organic sulfur compound(s) is from 0.01 to 10% by weight.   
     
     
         7 . The etching liquid according to  claim 4 , wherein the concentration of the α-hydroxycarboxylic acid and/or the salt thereof is from 0.2 to 5% by weight. 
     
     
         8 . An etching method, comprising etching titanium selectively in the presence of copper by using the etching liquid recited in  claim 1 .