Study on discharge characteristics of anode layer ion source based on PIC-MCC simulation

The spatio-temporal evolution of ion-beam characteristics and etching performance of ALIS were investigated with the combination of experimental and PIC-MCC simulation methods. The discharge characteristics and plasma evolution of ALIS were found to be significantly affected by anode voltage and Ar flow rate. With anode voltage increasing from 1200 V to 2400 V, both the discharge current and the power exhibited obvious upward trends, so did the increase of Ar flow rate. Meanwhile, the simulation results revealed that the charge density in discharge channel increased rapidly with the increase of anode voltage or Ar flow rate, and the emitting energy and density of Ar+ ions were enhanced effectively, in good agreement with the experimental results. The transport space for Ar+ ion beams can be separated into three regions: i. the emitting region with the highest Ar+ energy value of similar to 220 eV, driven by the anode sheath and Hall current; ii. the diffusion region, reduced energy due to kinetic energy transfer via particle collisions; iii. the acceleration region, driven by the substrate sheath, acting as a vital factor for the energy adjustment of the bombarding ions. As for etching properties, due to energetic-ion bombardment, the surfaces appeared to be ion polished as well as etched significantly, and the maximum etching rate of similar to 41 nm/min was obtained.