| 摘要 |
PURPOSE:To efficiently produce an optical thin film which is lessened in film loss on a non-heated substrate by irradiating the fluoride arranged in a vacuum vessel with the plasma generated by an arc discharge to evaporate this fluoride by heating and introducing reactive gases into the vessel. CONSTITUTION:Voltage is impressed to a cathode 2 of an electron gun 50 and a crucible holding means (anode) 7 arranged in a vacuum vessel 6 to generate the arc discharge and to convert the Ar, etc., supplied from a gas introducing port 4 to the plasma. This plasma is drawn out into the vacuum vessel 6 which is further maintained at the higher vacuum by intermediate electrodes 3, 4 from a plasma forming chamber 51 and is converged and deflected by an air core coil 14, a permanent magnet 8, etc. The conductive crucible 19 is irradiated with this plasma. As a result, the MgF2 housed in the crucible 19 is indirectly heated and evaporated. Gaseous SF6 is introduced from a reactive gas supply port 10 simultaneously therewith. As a result, the high-density and high quality optical thin film of the MgF2 is formed with a good adhesion property on the surface of the non-heated quartz glass substrate 12 placed on a substrate holder 18 to which bias voltage is impressed by a power source 11. |
