Ultra shallow secondary ion mass spectrometry depth profiling: Limitation of sample rotation in improving depth resolution

Abstract

Depth resolution deterioration attributed to crater bottom roughness induced by 500 eV O 2 + ion bombardment at 56° incidence angle is investigated. During this secondary ion mass spectrometry (SIMS) depth profiling process, sample rotation and oxygen flooding were applied to assess their effectiveness in suppressing surface roughness. Oxygen flooding was found to effectively suppress roughening and gives the best depth resolution at the energy and incident angle used. Although sample rotation was found to suppress roughening, the depth resolution was still degraded, which is counter-intuitive. Profiles fitted to the Hofmann model suggest that ion beam mixing may limit the depth resolution in low energy ion profiling.