| 摘要 |
According to the present invention, in changing the concentration of a treatment solution supplied to a substrate, a volume of an existing treatment solution in a tank connected to a treatment solution supply section for supplying the treatment solution to the substrate is first measured. Based on this measured value, a minimum drain volume of the existing treatment solution to be drained out from the tank and a supply volume of either a treatment solution with a predetermined concentration or a diluting fluid to be supplied into the tank is calculated respectively in order to change the treatment solution in the tank to be in an intended volume and to have an intended concentration. Then, the calculated drain volume of the existing treatment solution is drained out from the tank. Meanwhile, the calculated supply volume of either the treatment solution with the predetermined concentration or the diluting fluid is supplied into the tank. According to the present invention, since the drain volume in changing the concentration of the treatment solution can be reduced, a wasteful consumption volume of the treatment solution is reduced accordingly so that cost reduction can be realized. Moreover, the time required for the concentration change can be shortened.
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