| 摘要 |
PURPOSE:To keep illuminance of ultraviolet rays constant while a lamp is lighting by a method wherein composition, etc., of gas in the atmosphere of an ultraviolet lamp is changed according to the illuminance of ultraviolet rays. CONSTITUTION:Ashing is carried out when ozone gas is supplied on a wafer 1 via a nozzle 5 and ultraviolet rays are irradiated from an ultraviolet lamp 3. Composition ratio (O2 concentration for example) of atmospheric gas inside a lamp chamber 7 is changed according to illuminance of ultraviolet rays of the lamp 3 to keep it constant. Or not only the composition ratio but also composition is changed (O2+O3 O2+N2, for example). Kind of gas is further changed (O2 N2, for example), Further, the pressure of gas is changed. This keeps illuminance of ultraviolet rays constant, eliminating necessity of changing ashing conditions according to the lighting time of the lamp 3. |
