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Generation and extinction characteristics of negative ions in pulse-time-modulated electron cyclotron resonance chlorine plasma

The time dependence of plasma parameters in a pulse-time-modulated electron cyclotron resonance plasma of and Ar source gases is measured. It is found that plasma produces a large quantity of negative ions during afterglow and decay times of electron density, electron temperature and sheath potential of plasma are much smaller than those of Ar plasma. The negative ions in plasma stay for a long time in the afterglow and they quickly become extinct when the microwave power is turned on. These characteristics suggest that the pulse modulation of plasma produces a large amount of negative ions and changes the flow of charged particles through the sheath region to the substrate surface, which enables us to improve highly anisotropic and charge-free poly-Si etching.