[Analysis of optical emission spectra from ICP of Ar in the vicinity of plasma sheath]

In order to control the ion density and energy distribution in the vicinity of plasma sheath independently, the inductively coupled plasma and its glow discharge mechanism in the vicinity of plasma sheath were studied by means of optical emission spectroscopy (OES) under different RF power, different discharge and different substrate DC bias voltage. It was shown that the ion density is higher and the electron temperature is lower in the vicinity of inductively coupled plasma sheath according to the ionic line and atomic line. With changing the discharge pressure and RF power, the spectral characteristics analysis shows that the ion density in the vicinity of plasma sheath linearly increases with the RF power and rises with the pressure under the low pressure. The atomic spectral intensity of low excitation states increases rapidly. The atomic spectral intensity of high excitation states rises slowly and the intensity of ion spectrum increases not obviously. By applying the DC bias voltage to substrate, the intensity of emission spectroscopy was analyzed. The result shows that the intensity of spectra rises with the increase in positive bias voltage, while first reduces then increases with the increase in negative bias voltage, and is the weakest in the case of DC bias at -30 V. This shows that the fast ions and the electrons are the main source of energy for Ar ionization and excitation.