Abstract: An etching agent for a semiconductor substrate, which is capable of etching a titanium (Ti)-based metal film on a semiconductor substrate and an etching method using the etching agent, and relates to a liquid for preparing the etching agent for a semiconductor substrate composed of a solution comprising (A) hydrogen peroxide, (B) a phosphonic acid chelating agent having a hydroxyl group, (C) a basic compound, and (D-1) a copper anticorrosive. An etching method for etching a titanium (Ti)-based metal film on a semiconductor substrate using the etching agent. A solution comprising (B) a phosphonic acid chelating agent having a hydroxyl group, (C) a basic compound, and (D-1) a copper anticorrosive.

Abstract: To provide an environmentally-friendly method for producing industrially an ester compound. SOLUTION The present invention is a method for producing an ester compound which comprises subjecting a carboxylic acid and an alcohol to dehydration-condensation reaction using an involatile acid catalyst and then removing the residual acid catalyst by bringing a weak basic substance into contact with the residual acid catalyst.