Broad ion beam modeling for extraction optics optimization and etching process simulation

Abstract

A model for calculating the ion–current density distribution of a broad-beam ion source at the target level is proposed. Three model parameters related to a single beamlet such as the beam divergence, the maximum ion–current density in the beamlet center, and a possible misalignment between the different grids are needed to describe the overall extraction performance. These parameters were determined partially with the axcel simulation code or experimentally via etch tests. In this work the model parameters have been determined for a capacitively coupled filamentless 13.56 MHz rf source operated with argon at low power levels ranging from 20–100 W and low acceleration voltages (100–1000 V). However, the model proposed is applicable also for other types of ion sources, for different extraction grid sets with varying geometry and a wide range of working conditions. Intensity profiles predicted by the above model show good agreement with experimental results.