Ion energy and angular distributions in planar Ar/O2 inductively coupled plasmas: hybrid simulation and experimental validation

Abstract

A hybrid model, which consists of a fluid module, a sheath module and an ion Monte Carlo module, is employed to investigate the dependence of ion energy and angular distributions (IEDs and IADs) on the inductively coupled plasma (ICP) power, pressure, gas ratio, bias power and bias frequency in Ar/O2 discharges. The results indicate that the bimodal distribution appears as bias power increases or bias frequency decreases. Moreover, the low and high energy peaks of IEDs move to higher energy with the rise of bias power and O2 content. Whereas, an opposite tendency is observed with the increase of ICP power and pressure. For IADs, it is clear that a larger percentage of ions incident on the electrode have a smaller deflection angle by increasing bias power or decreasing pressure, and a similar evolution is observed with the decline of bias frequency. Besides, the better collimation of ions is obtained at larger O2 concentration, but ICP power only has little influence on IADs. In order to validate the model, a comparison between the simulated IEDs and those measured by a retarding field energy analyzer has been done, and shows a good agreement. The results obtained in this work could help us to gain more insight into the dependence of IEDs and IADs on the discharge parameters, which is of significant importance in the improvement of the etching rate and anisotropy.