Substrate Damage-free Laser Shock Cleaning of Particles

No dry process has been able to remove inorganic particles effectively without inducing damage. Wet process, although effective, does use large amounts of water and is compatible with vacuum process. Many cleaning steps are used after dry process to remove particulate contaminants introduced during etching or thin film deposition processes. Laser cleaning has been considered by many as possible technique for the removal of particulate contaminants. However, the direct dry laser irradiation of wafers has not been shown to remove inorganic particles and could easily cause surface damage. Wet or laser cleaning has been shown to be effective in the removal of organic particles, however, it has been shown to damage patterned wafers. In this article, we introduce dry laser cleaning method using a shock wave generated just above the wafer surface. The particle removal is caused by the gas high velocity induced by the propagating shock wave.