PURPOSE: To remove the film deposited on the inner surface of a light transmission plate of a light transmission window by introducing the excited species of a nondepositing etching gas formed in an excited species forming device into a reaction vessel.
CONSTITUTION: A film is deposited on a substrate 3 in a reaction vessel 1 by a photochemical vapor phase growth method. At this time, before the formation of the deposited film on the substrate 3 is affected by the deposition of a film on a light transmission window 4, the irradiation of high-energy light 8 is temporarily stopped and the inside of a reaction chamber A is evacuated. Meanwhile, gaseous CF4, as the nondepositing etching gas, is introduced into an excited species forming chamber D from an introducing pipe 12, a microwave is generated by a microwave discharge device 11 to convert and gaseous CF4 into an excited species and the excited species of the nondepositing etching gas is formed. The formed excited species is introduced into a reaction vessel 1 through passages C and B by the pressure difference between the excited species forming chamber D and the reaction chamber A and the film deposited on the light transmission window 4 is etched and removed. Consequently, a uniform, homogeneous and high-quality deposited film is stably and efficiently formed on the substrate 3.
TAKASU KATSUJI
SANO MASAFUMI
HIRAI YUTAKA
