Patent ID: 7758920

Claim:
A film formation method for forming a silicon-containing insulating film on a target substrate by CVD, in a process field configured to be selectively supplied with a purge gas, a first process gas containing a silane family gas, and a second process gas containing a gas selected from the group consisting of a nitriding gas, an oxynitriding gas, and an oxidizing gas, the method being preset to repeat a cycle a plurality of times to laminate thin films formed by respective times, the cycle alternately comprising: a first step of performing supply of the first process gas to the process field, while maintaining stoppage of supply of the second process gas and the purge gas to the process field; a second step of performing supply of the purge gas to the process field, while maintaining stoppage of supply of the first and second process gases to the process field; a third step of performing supply of the second process gas to the process field, while maintaining stoppage of supply of the first process gas and the purge gas to the process field; and a fourth step of performing supply of the purge gas to the process field, while maintaining stoppage of supply of the first and second process gases to the process field, wherein the cycle comprises continuously vacuum-exhausting the process field over the first to fourth steps through an exhaust passage provided with an opening degree adjustment valve, such that an opening degree of the valve in the first step is set to be 5 to 20% of an opening degree of the valve in the second and fourth steps, so as to control balance between promotion of adsorption of the silane family gas onto the target substrate and decrease in the number of particles present within the process field, and an opening degree of the valve in the third step is set to be equal to the opening degree of the valve in the second and fourth steps, or to be larger than the opening degree of the valve in the first step and smaller than the opening degree of the valve in the second and fourth steps.