An apparatus and method are provided for cleaning (removing) contaminating particles and/or films from substrate surfaces such as semiconductor wafers during the fabrication process for making electronic components. The method and apparatus use a liquified gas contained in a distributor which has been energized with megasonic energy in the distributor and the energized liquefied gas directed as a stream against the surface to be cleaned from an outlet distribution nozzle of the distributor. The stream is preferably impinged on the substrate surface at an acute angle. The preferred liquified gas is carbon dioxide.