Coating apparatus

A coating apparatus configured to coat a substrate with a treatment solution, comprising:

• a substrate holding member configured to hold the substrate;
• a treatment solution supply having a plurality of treatment solution tanks which contain treatment solutions of different compositions;
• a solvent supply which contains a solvent;
• a confluence valve coupled to the solvent supply and the treatment solution supply, said confluence valve including:
• a main treatment solution passage,
• switch means for selectively switching a transfer of a treatment solution from said plurality of treatment solution tanks to said main treatment solution passage,
• a solvent passage coupled to the solvent tank,
• a valve seat provided in the solvent passage,
• a first valve body for opening and closing the solvent passage, and
• a first valve cylinder for bringing the first valve body into and out of contact with the valve seat;
• first pump means for supplying the treatment solution from the treatment solution supply to the confluence valve, said first pump means including a first flexible tube coupled to a treatment solution reservoir, and a first pump cylinder means for reciprocating the flexible tube;
• second pump means for supplying the solvent from the solvent supply to the confluence valve, the second pump means including a second flexible tube coupled to a solvent reservoir, and a second pump cylinder means for reciprocating the flexible tube;
• a mixer provided downstream of the confluence valve and configured to mix the treatment solution and the solvent supplied from the confluence valve;
• nozzle means coupled to said mixer and having a solution discharge portion for applying a solution from the mixer, to the substrate held by the substrate holding member;
• a discharge valve located downstream of the mixer and in the vicinity of the nozzle means and configured to permit and interrupt a flow of a solution from the mixer to the nozzle means;
• a sensor means for sensing an amount of displacement of said flexible tubes;
• and
• control means for controlling said first and second cylinder means on the basis of a detection signal from said sensor means thereby controlling the first and second pump means to adjust a mixture ratio of the treatment solution to be supplied from the treatment solution supply to the confluence valve, to the solvent supplied from the solvent supply to the confluence valve.