Characteristics of ultra-low-energy Cs+ ion beam bombardments

Shallow arsenic implants and extra-thin film (SiON) are routinely analyzed by modern SIMS under ultra-low-energy Cs+ ion beam bombardment, either at oblique (<60°) or glancing (∼80°) incident angle [J. Surf. Anal. 6 (3) (1999) A-3; in: A. Benninghoven, et al. (Eds.), Proceedings of the SIMS XII, Elsevier, Amsterdam, 1999, p. 549]. This article investigates the basic aspects of ultra-low-energy Cs+ ion beam bombardment using a delta-doped boron sample (four layers, 5.3 nm per cycle), such as useful yield, depth resolution and changes in sputter rate in the near surface region. Our results indicated that there is a magic incidence angle (∼70°) at which the depth resolution is very poor, and at glancing (∼80°) incident angle the best depth resolution is observed.