Processing solution preparation and supply method and apparatus

A processing solution preparation and supply apparatus for preparing a processing solution for use in processing of a substrate on which an element is to be formed, and supplying said processing solution to an apparatus for processing said substrate, comprising:

• a preparation bath to which a solid material powder of said processing solution and pure water are supplied, and in which said processing solution is prepared by dissolving said solid material powder in said pure water;
• a solid material powder supply unit which is connected to said preparation bath and stores said solid material powder;
• a pure water supply unit connected to said preparation bath;
• a pipeline which is connected to said preparation bath and a substrate processing apparatus, and through which said processing solution is supplied from said preparation bath to said substrate processing apparatus, wherein in said pure water supply unit, said pure water is continuously or intermittently circulated or allowed to flow such that a microorganism concentration in said pure water or said processing solution is not more than 100 times an initial value of said microorganism concentration;
• and
• a dissolution assistant supply unit which is connected to said preparation bath and stores a dissolution assistant for promoting dissolution of said solid material power in said pure water.