Laser cleaning of IC mould and its real-time monitoring

Laser-induced removal of organic contaminants on IC mould surfaces was studied both experimentally and theoretically. The mould surfaces before and after cleaning were observed under an optical microscope and analyzed by Auger electron spectroscopy (AES). It was found that the contaminants in the irradiated area were effectively removed by pulsed laser irradiation at a laser fluence greater than the cleaning threshold of 100 mJ/cm². The cleaning efficiency increases with increasing laser fluence and the damage threshold of the mould surfaces is about 1.05 J/cm², which is in good agreement with the theoretical damage threshold. We also demonstrated that the acoustic wave detection in real-time can be used to both monitor the surface cleanness during the laser cleaning process and determine the cleaning threshold and cleaning efficiency.