| 摘要 |
PURPOSE:To prevent decline of the effect of environmetal pllution preventing treatment regarding waste water disposal by decomposing hydrogen peroxide included in the waste water of semiconductor substrate surface cleaning process in advance as the preliminary treatment of acid and alkali-group waste water. CONSTITUTION:A constant quantity of solutions from each of a hydrogen peroxide water solution tank 1 and a tank 2 of an alkali water solution such as ammonia water are supplied to a semiconductor substrate cleaning tank 3. A semiconductor substrate 9a is inserted in the tank 3 and is cleaned for a constant time by vertical vibration or a supersonic vibration mechanism. The semiconductor substrate 9a is carried to the next rinsing tank 4 after the constant time has passed. In some cases, the substrate passes a hydrofluoric-acid cleaning tank 5 and is cleaned by a rinsing tank 6 and lastly is dehydrated and dried. A cleaning solution from the tank 3 and a rinsing water from the tank 4 are transported to a hydrogen peroxide decomposition tank 8. In the tank 8, a constant quantity of iron pieces and strips of iron comprising an oxide film on the surface as a decomposition promoting agent are put and the waste water of the tank 3 and the tank 4 is kept in the tank 8 for a necessary time, e.g. 8hr during night. By action of the iron comprising a oxide film, the hydrogen peroxide included in the cleaning solution and the rinsing water is decomposited to under the aimed concentration. |
