Precleaning method of precleaning a silicon nitride film forming system

摘要

A thermal processing system (1) includes a reaction vessel (2) capable of forming a silicon nitride film on semiconductor wafers (10) through interaction between hexachlorodisilane and ammonia, and an exhaust pipe (16) connected to the reaction vessel (2). The reaction vessel 2 is heated at a temperature in the range of 500 to 900° C. and the exhaust pipe (16) is heated at 100° C. before disassembling and cleaning the exhaust pipe 16. Ammonia is supplied through a process gas supply pipe (13) into the reaction vessel (2), and the ammonia is discharged from the reaction vessel (2) into the exhaust pipe (16).