Defect profiling by ellipsometry using ion implantation through wedge masks

Abstract

AbstractWe measured 3.5 MeV energy He‐ and N‐implanted Si by spectroscopic ellipsometry (SE) and Rutherford backscattering/channeling spectrometry (RBS/C). The He and N ions were implanted in the range of 1–5x1016/cm2 and 0.2–1.2x1016/cm2, respectively through a wedge‐shape silicon membrane (∼4.5 micron/mm slope) which was fixed to the target wafer and was moved laterally to the ion beam spot causing the disorder (mainly point defects) profile “moving” in depth. The doses and energies were in both cases set to have all the positions of the Gaussian damage at the surface, and to cover the damage range from slightly damaged to the maximum. We used ∼0.1 mm wide measuring spots for both SE and RBS/C making possible to “scan” the disorder profiles with ∼0.5 micron depth resolution. Several nm thick, surface amorphous damage peak was observed with low level (far below the modified Kinchin‐Pease model predictions) point defect region beneath the surface, possibly due to dynamic annealing processes. Using critical point analysis we make an attempt to determine the optical response (dielectric function) of the point defects or defect complexes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)