Patent ID: 8267037

Claim:
A substrate processing apparatus comprising: a holder 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 holder; a treatment chamber housing said holder and said coating solution supply nozzle; a cooling device which cools the substrate to be processed before the coating solution is supplied to the substrate to be processed, to a predetermined temperature; a heating device that heats the substrate to be processed coated with the coating solution to a predetermined temperature; and a transferer that transfers the substrate to be processed between said treatment chamber, said cooling device and said heating device, wherein said treatment chamber, said cooling device and said heating device are partitioned from an ambient air, wherein at least said treatment chamber 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, wherein said gas supply mechanism has a circulation pipe connecting a gas supply port for supplying the gas into said treatment chamber and an exhaust port for exhausting the gas in said treatment chamber, and wherein said gas supply mechanism has a gas temperature and humidity regulator for regulating temperature and humidity of the gas in said circulation pipe, a gas concentration sensor, and a gas/liquid separator for separating the gas exhausted from said exhaust port into gas and liquid and returning only the gas into said circulation pipe, and further has a gas supply source for replenishing said circulation pipe with the gas based on a detection signal from said gas concentration sensor.