Damage-Free Design of a Megasonic Waveguide for Single-Wafer Processing

Megasonic cleaning process as a wet cleaning process is routinely used in the semiconductor industry for the removal of contaminant particles from wafer surfaces. The wafer surfaces can be cleaned effectively by choosing the proper chemicals, acoustic pressure, and the frequency of acoustic field. In the present study, we propose the design improvement of a megasonic waveguide to minimize wafer damage from the bubble cavitation. The conventional direct-type waveguide is compared with the newly designed and developed indirect-type waveguide in terms of its performance in minimizing the damage of wafers having 70 nm poly-Si patterns.