| 摘要 |
PURPOSE:To enhance etching accuracy by providing a pH measuring means and a means for controlling supply of chemical solution based on such pH value in the case of forming an etching apparatus with the processing layer of overflow system, a chemicals circulation system which filters the overflow amount of chemical solution and returns it to the processing layer by controlling a temperature of chemicals and a means for newly supplying chemicals thereto. CONSTITUTION:The chemical solution sent from a chemical solution supply tank 1 being filled with a fresh chemical solution for oxide film etching is dropped into an external tank 3 surrounding a processing tank 4 accommodating semiconductor wafer on which surface an oxide film is formed. A chemical solution is extracted from the bottom part of tank 3 using a pump 6, it is then circulated to the aperture of bottom part of tank 4 through a filter 7 having the exhaust valves 9, 10 and a chemical solution temperature adjusting part 8 and an overflow amount is returned to the tank 3. In such a structure, the chemical solution in the tank 4 is sampled in a liquid reservoir 13 comprising a pH detector 14 and amount of supply to the tank 3 is adjusted by controlling the valve 2 of tank 1 in accordance with indication of pH meter 15. |
