Substrate processing apparatus

A substrate processing apparatus comprising a holding means for rotatably holding a substrate to be processed;

• a coating solution supply nozzle for supplying a coating solution onto a front surface of the substrate to be processed held by said holding means;
• a treatment chamber housing said holding means and said coating solution supply nozzle;
• a cooling means for cooling the substrate to be processed before the coating solution is supplied to the substrate to be processed, to a predetermined temperature;
• a heating means for heating the substrate to be processed coated with the coating solution to a predetermined temperature;
• and a transfer means for transferring the substrate to be processed between said treatment chamber, said cooling means and said heating means,
• wherein said treatment chamber, said cooling means and said heating means are partitioned from an ambient air,
• wherein said treatment chamber, said cooling means, said heating means, and said transfer means are provided in a casing partitioned from an ambient air, and
• wherein said casing is connected to a gas supply mechanism having a supply source of a gas having a kinematic viscosity coefficient higher than that of air and kept at a predetermined concentration of the gas.