Frequency optimization for capacitively coupled plasma source

Design of an all-in-one (main etch, PR ash and clean) dielectric etch chamber requires independent control of plasma generation from ion energy. Plasma simulation has been performed for a capacitively coupled discharge to study frequency effect on electron density, power deposition, and dissociation fraction. Simulation results demonstrate that plasma production efficiency enhances with increase in frequency while energy of the bombarding ions diminishes. A very high frequency source has been developed to generate high density plasma while radio frequency bias has been used to control ion energy. As illustrated, the etch rate for a dual damascene trench etch process increases, while damage due to ion bombardment is reduced. The dissociation fraction is well behaved to provide necessary corner protection. High-frequency source was used to achieve better performance for dual damascene trench etch process.