SAMPLE ROTATION AND REDUCED SURFACE ROUGHENING IN OBLIQUE-INCIDENCE ION SPUTTERING EROSION

The effects of sample rotation upon surface roughening during oblique incidence ion irradiation, as used in sputter-sectioning composition d epth-profiling, are examined theoretically. Surface roughening due to statistical ion impact and sputtering is compensated by irradiation-in duced viscous flow, surface atomic drift and diffusion and surface gra dient dependent sputtering yield smoothing processes which can result in steady-state roughness values. The amplitude of such roughness can be less than tens of equivalent atomic layers but sputtered depths to achieve this steady-state are considerable fractions of sample lateral dimensions. Small diameter analytic probe beams, however, evaluate a quasi-saturation situation at eroded depths which are a similar fracti on of probe diameter. (C) 1998 Elsevier Science Ltd. All rights reserv ed.