| 摘要 |
PURPOSE:To keep etching accuracy constant by preventing the variation in the composition of an etching liquid, by regenerating the etching liquid during use by passing the same through an ion exchange resin tower at proper SV to reuse the same as the etching liquid. CONSTITUTION:In etching for a thin Al-film forming circuit, an etching liquid 2 during use having a composition comprising about 40% of acetic acid, about 40% of phosphoric acid, about 10% of nitric acid and about 10% of water received in an etching tank 1 is successively passed through an ion exchange resin tower 5 packed with a strong acidic cation exchange resin, a filter 6 and a heat exchanger 7 by using a pump 3 while SV thereof is adjusted to 1-20 by a flow meter 4. By this method, the Al-ion dissolved in the etching liquid 2 is removed by adsorption to regenerate the etching liquid 2 which is, in turn, returned to the etching tank 1 while adjusted to about 35 deg.C to be reused as the etching liquid. |
