SUBSTRATE PROCESSING APPARATUS AND METHOD OF PROCESSING SUBSTRATE

Provided is a substrate processing apparatus and a substrate processing method, capable of preventing a reactive product from being deposited to the inside of a processing chamber and an exhaust line, and preventing the corrosion caused by hydrogen chloride gas. The method includes (a) forming a film on a substrate in a processing chamber; and (b) introducing an air from an outside of the processing chamber into an inside of the processing chamber, reacting an adherent adhered to the inside of the processing chamber and an inside of an exhaust line connected to the processing chamber with a moisture contained in the air to generate at least a hydrogen chloride gas, and exhausting the hydrogen chloride gas through the exhaust line, wherein the step (b) is performed after performing the step (a) and the step (b) is performed until a concentration level of the hydrogen chloride gas in the processing chamber is equal to or lower than a preset concentration level.