An analytical model for time-averaged ion energy distributions in collisional rf sheaths

作者：Chen Wen Cong^*; Pu Yi Kang

来源：Journal of Physics D: Applied Physics , 2014, 47(34): 345201.

DOI：10.1088/0022-3727/47/34/345201

• ion energy distribution
• collisional rf sheath
• ion-neutral collisions
• charge transfer

An analytical model is proposed for time-averaged ion energy distributions (IEDs) in collisional rf sheaths (lambda(i) < s(m), where lambda(i) is the ion mean free path and sm is the sheath thickness), in which charge transfer is the dominant ion-neutral collision mechanism. Our model is different from the model in Israel et al 2006 J. Appl. Phys. 99 093303 in two aspects. Firstly, to calculate the ion flux, we consider ions created in both the space charge region and the quasi-neutral region instead of only the quasi-neutral region. Secondly, to calculate the ion energy, we use an rf-modulated transit time instead of only the average transit time. Consequently, our model is valid over a wider pressure range (from a weakly collisional sheath to a strongly collisional sheath) compared with the model in Israel et al 2006 J. Appl. Phys. 99 093303. Our model shows that, in a collisional rf sheath (argon, 5 Pa, 27.12MHz and 100 W), 65% of the ion flux in the IED comes from secondary ions created in the space charge region. Results of our model are compared with those obtained by measurement, direct integration method and particle-in-cell/Monte Carlo collision simulation.

• 出版日期2014-8-30
• 单位清华大学