METHOD FOR TREATING SUBSTRATE

PROBLEM TO BE SOLVED: To prevent particles blown out by a reverse flow. SOLUTION: This epitaxial treating method forms a thin film on a wafer 1 using an epitaxial device in which a general exhaust pipe 26 and a treating exhaust pipe 29 connected to a treatment chamber 14 by opening valves 42, 44 or 43 for a pipe for differential manometer 40 during switching from general exhaust pipe 26 to treating exhaust pipe 29 or from treating exhaust pipe 29 to general exhaust pipe 26 to enable to observe the differential pressure between the internal pressure of treatment chamber 14 and general exhaust pipe 26 or treating exhaust pipe 29 with differential manometer 41 and then by closing treatment exhaust valve pipe 34 followed by general exhaust valve 28. The internal pressure of treatment chamber 14 is pressed higher so that it becomes positive pressure than the exhaust pressure of treating exhaust pipe 29 or general exhaust pipe 26 to prevent a reverse flow from the exhaust pipes to the treatment chamber. Thus, the blown out particles can be prevented.