| 摘要 |
PURPOSE:To solve the problem of the dissolution of an injurious material such as aluminum, and to eliminate the wasting of a treating liquid by installing a photosensor composed of a light emitter and a photoreceptor oppositely faced to the light emitter while interposing the treating liquid and alarming the exchange period of the treating liquid by an output from the photosensor. CONSTITUTION:A light emitter 5 and a photoreceptor 6 are opposed and installed while interposing a treating liquid 4 from the outside of a dipping vessel 1, and constitute the photosensor for detecting the turbidity of the treating liquid. An alarm 8 giving an alarm while making a detecting output from the photosensor corresponding to the exchange period of the treating liquid 4 is mounted. That is, fuming nitric acid as the treating liquid 4 changes from brown to yellow green and transparency with the increase of the number of the dipping treatment of a wafer 2, but the exchange period when the treating liquid no longer resists dipping treatment is detected by the light emitter 5 and the photoreceptor 6 as the photosensor, thus flickering the alarm lamp 8. Accordingly, the dipping treating liquid can be exchanged easily and accurately. |
