Characterization of a broad beam Kaufman-type ion source operated with CHF₃ and O₂

Process stability and reproducibility are essential for highly precise manufacturing with reactive ion beam etching (RIBE) in optics industry. Therefore, the ion beam source characteristic must be well known. For this study, a Kaufman-type broad beam ion source operated with CHF3 and O-2 is characterized with energy selective mass spectrometry and Faraday measurements. These results are compared with etching experiments on SiO2, Si, and AZ (R) 1505 photo resist. The influence of the source setup and process conditions on ion beam composition, ion energy distribution, and the etch selectivity are discussed. It was found that etch selectivity applying different ion beam currents at a fixed feed gas composition correlate with resulting ion beam composition. Due to a change in ion beam composition, selectivity also changes with the total volumetric mass flow of the feed gas at a fixed ion beam current and constant mixing ratio of CHF3 and O-2