| abstract |
(57) [Summary] [PROBLEMS] To easily remove a reaction product attached to the inside of a reaction chamber in a short time. SOLUTION: During the film forming process, the pressure in a reaction tube 11 is controlled by a combination valve CV, hydrocarbons and the like are removed by a hot disk trap TRP1, and ammonium chloride is removed by a switching trap TRP2. Next, the reaction chamber 11 and the pipe 63a are heated to 100 ° C. to 150 ° C., and the combination valve CV is used to heat the pipe 63a. While maintaining the inside at a pressure of 10 kPa to 30 kPa, hydrogen fluoride of the gas source 35 d is supplied from the inlets 64 a to 64 c to the portions where the conductance and the temperature of the exhaust gas decrease, and the exhaust gas is washed. Also, the combination valve C Cleaning may be performed by supplying hydrogen fluoride while changing the inside of the pipe 63a between 0.1 kPa and 30 kPa with V. Further, after completion of the cleaning, the hydrogen fluoride used for the cleaning is efficiently removed by supplying the alkoxysilane for a predetermined time. |