JPH05291221

PURPOSE:To remove contaminative particles of 0.1mum or lower and to completely remove a molecular contamination composed of an organic substance and a contamination composed of carbonic acid by a method wherein an object to be cleaned is immersed in a solution in which ozone has been dissolved or in a liquid in which ozone gas has been bubbled and the surface of the object to be cleaned is irradiated with ultraviolet rays. CONSTITUTION:An object 2 to be cleaned is immersed in a liquid 6 in which ozone has been dissolved or in a liquid in which ozone gas has been bubbled; the surface of the immersed object 2 to be cleaned is irradiated with ultraviolet rays; the object is cleaned. For example, a low-pressure mercury lamp 3 as an ultraviolet-ray generation source and a liquid 6 which is used for cleaning and in which ozone has been dissolved are housed in a cleaning tank 1. The liquid 6 in which the ozone has been dissolved is dissolved in a liquid while ozone gas 5 which has been produced inside an ozone-gas generator 8 and a liquid 4 inside a liquid storage tank 7 are fed into an ozone decomposition device 9. The liquid 6 is supplied sequentially through an insertion pump 10, and an electric current is supplied to the low-pressure mercury lamp 3. Thereby, the surface of an object 2 to be cleaned is irradiated with ultraviolet rays.