Film formation method and film formation apparatus

1. A film formation method, comprising:

vaporizing a plurality of raw material monomers in respective corresponding vaporizers;

supplying the plurality of raw material monomers via a plurality of supply tubes including a first supply tube and a second supply tube that is arranged inside the first supply tube into a film formation apparatus, said first and second supply tubes supplying different raw material monomers during the supplying step;

causing vapor deposition polymerization of the plurality of raw material monomers in the film formation apparatus to form an organic film on a substrate; and

removing an impurity contained in at least one raw material monomer among the plurality of raw material monomers before the vapor deposition polymerization,

wherein the removing of the impurity is conducted in the corresponding vaporizer filled with the raw material monomer containing the impurity while supplying an inert gas at a flow rate at a time of removal of the at least one of acetic acid and acetic anhydride is in a range of 8.33×10 −7 m 3 /s to 8.33×10 −6 m 3 /s into the corresponding vaporizer under a reduced pressure of 1.33×10 4 Pa˜2.66×10 4 Pa with a valve provided at a corresponding supply tube being closed, and wherein the removing of the impurity is performed when each of the plurality of raw material monomers is contained in a plurality of trays that are arranged at a predetermined interval in a vertical direction of the corresponding vaporizer.

2. The film formation method as claimed in claim 1 , wherein the removing an impurity includes volatilizing the impurity.

3. The film formation method as claimed in claim 1 , wherein the organic film is selected from the group consisting of a polyimide film, a polyurea film, a polyurethane film, and a polyazomethine film.

4. The film formation method as claimed in claim 3 , wherein the organic film is a polyimide film, the plurality of raw material monomers are an acid dianhydride and a diamine, and the impurity is at least one of acetic acid and acetic anhydride contained in the acid dianhydride.

5. The film formation method as claimed in claim 4 , wherein a concentration of the at least one of acetic acid and acetic anhydride in the acid dianhydride is 400 ppm or less after the removing of the impurities.

6. The film formation method as claimed in claim 4 , wherein the removing an impurity is conducted at a temperature of 120° C. to 180° C.

7. The film formation method as claimed in claim 1 , wherein the removing step removes at least one of acetic acid and acetic anhydride component.

8. The film formation method as claimed in claim 1 , wherein the suppling step is performed via the first supply tube including a plurality of supply ports that are arranged at a downstream side relative to the second supply tube.