| abstract |
(57) [Problem] To effectively reduce fluoride generated by a cleaning process. SOLUTION: A film forming material formed on an inner wall or the like of a film forming chamber is removed in a cleaning step, fluorine is removed from AlF generated on an inner wall of the film forming chamber in a reducing step, and oxidized on the inner wall in an oxidizing step. The remaining AlF covered by the film is oxidized and fixed, and fluorine is removed by sputtering. AlF particles are discharged by the purge process, The fluoride is completely removed, effectively reducing the fluoride generated by the cleaning process. |