Evaluation of a dry laser cleaning process

Laser cleaning is one of the new promising dry cleaning techniques considered by semiconductor companies to replace met cleans in the near future. Radiance Process(TM) uses an inert gas jet to remove particles lifted off by the action of a DUV excimer laser. The efficiency of the process in removing Si3N4 and SiO2 particles on Si wafers was optimized by varying laser beam fluence and repetition rate, and the number of laser pulses. The experimental results were compared with theoretical calculations simulating the particle lift off process. Higher efficiencies were obtained upon exposure of wafers to air saturated with moisture prior to laser processing.