US Patent 7392814 Substrate processing apparatus and method

Pure water dissolving nitrogen gas and containing microbubbles is supplied to a substrate. Since microbubbles are very minute in size and also have the electrostatic property, they can efficiently adsorb particles on the substrate surface or in the pure water. Further, since pure water dissolving nitrogen gas is unlikely to be charged, the pure water itself never carries new particles from each component of the apparatus. These functions allow efficient particle removal from the substrate surface or the liquid.