Abstract: A method and device for treating substrates, and a nozzle unit therefore. A liquid film is formed on a local surface area of a substrate that is to be treated by means of a nozzle unit comprised of at least on elongated nozzle arrangement and an ultrasonic or megasonic transducer arrangement disposed adjacent to the nozzle arrangement. The transducer arrangement is composed of a plurality of transducers having different resonant frequencies. At least a portion of the transducer arrangement is brought into contact with the liquid film, and ultrasound or megasound is introduced into the liquid film by the transducer arrangement.

Abstract: The present invention relates to a novel and advantageous process for cleaning substrates, in particular masks and mask blanks. The process according to the invention is characterized by consecutive process steps comprising UV-treatment, fulljet cleaning, megasonic cleaning and DI (deionized) water cleaning. The process does not include an acid cleaning step.