| abstract |
[Object] To provide a manufacturing method of an optical filter having favorable film quality by removing a foreign substance adhered onto a surface of a substrate by cleaning before a thin film is formed. n [Solution] By performing a cleaning step P1 for cleaning a substrate S by means of a solution including water, a pre-treatment step P3 for plasma-treating a surface of the substrate S cleaned in the cleaning step P1 by plasma of an oxygen gas, and a thin film formation step (P4, P5) for forming the thin film on the surface of the substrate S plasma-treated in the pre-treatment step P3, the foreign substance adhered onto the surface of the substrate can be effectively removed. In the pre-treatment step P3, only the oxygen gas is introduced to an area where the plasma is generated, and a flow rate of the oxygen gas to be introduced is greater than a flow rate of the oxygen gas introduced in the thin film formation step. Thus, the foreign substance adhered onto the surface of the substrate S through OH bonds in the cleaning step is effectively eliminated before the thin film formation step (P4, P5), so that generation of a film absent part is prevented. |