Ultraviolet-Ozone Cleaning of Semiconductor Surfaces

Abstract

The ultraviolet (UV)/ozone surface-cleaning method, which is reviewed in this report, is an effective method of removing a variety of contaminants from silicon (as well as many other) surfaces. It is a simple-to-use dry process which is inexpensive to set up and operate. It can rapidly produce clean surfaces, in air or in a vacuum system, at ambient temperatures. In combination with a dry method for removing inorganic contamination, the method may meet the requirements for the all-dry cleaning methods that will be necessary for future generations of semiconductor devices. Placing properly precleaned surfaces within a few millimeters of an ozone-producing UV source can produce clean surfaces in less than one minute. The technique can produce near-atomically clean surfaces, as evidenced by Auger electron spectroscopy, ESCA, and ISS/SIMS studies. Topics discussed include the variables of the process, the types of surfaces which have been cleaned successfully, the contaminants that can be removed, the construction of an UV/ozone cleaning facility, the mechanism of the process, UV/ozone cleaning in vacuum systems, rate-enhancement techniques, safety considerations, effects of UV/ozone other than cleaning, and applications.