Observation of Removal Process of Thin Metal Film on Glass Surface by Steam-Water Mixed Spray: Application to Au Film Removal in LED Manufacturing

Abstract

In the LED manufacturing process, a thin Au film is deposited on a wafer, and then most of it is removed with small pieces of Au film left for electrodes. For this removal, we apply physical cleaning method, which can remove the metal film without chemicals. In this study, we investigate a removal process of a thin aluminum film deposited on a glass surface by steam-water mixed spray. At the initial stage of this process, tiny spots, whose sizes are the order of droplet diameter, are observed. And then very characteristic removal profiles, which are typically lines with sub-millimeter width, are observed. We discuss the removal mechanism due to high-speed droplet impact.