Design and fabrication of an L-type waveguide megasonic system for cleaning of nano-scale patterns

An L-type waveguide megasonic system for nano-pattern cleaning that does not cause damage to the device was designed, manufactured and tested. The impedance of the quartz waveguide was simulated by using ANSYS finite element method (FEM) software. The peak value of the piezoelectric actuator alone was 1.107 MHz, which was the same as the experimentally measured value of 1.107 MHz (0.0% error). In addition, the maximum impedance value of the quartz waveguide with the actuator was 1.109 MHz, which agreed well with the measured value of 1.105 MHz (0.4% error). The acoustic pressure of a conventional megasonic system (1 MHz) and the L-type system was measured and compared. The results showed that the maximum values and standard deviations for the L-type system were decreased by 17% and 14%, respectively, compared with the conventional type. This suggests that the L-type would have higher particle removal efficiency and would be less likely to cause pattern damage.