| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method for semiconductor devices where a BPSG film having the film quality of a uniform composition in its film- thickness direction, etc., can be formed by suppressing impurities such as boron and phosphorous, from segregating in the early stages of their film formation. SOLUTION: In the manufacturing method for semiconductor devices, there is provided a first three-way valve 18 capable of changing over gas flow passages between a gas mixer 17 for mixing film-forming gases with each other and a shower head portion 14 for feeding a mixed gas to a film-forming chamber 11A. Also, a vacuum pump 23 is coupled to the first three-way valve 18 via a second three-way valve 20, etc. When performing film-forming of a BPSG film, the mixed gas fed from the gas mixer 17 is made to be evacuated by the vacuum pump 23 via the first and second three-way valves 18, 20, from the time when intending to begin the film-forming to a predetermined lapse of time. Thereafter, by changing over the first three-way valve 18, the mixed gas is introduced into the film-forming chamber 11A via the shower head portion 14.
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