Roughness development is one of the most often addressed issues in the secondary ion mass spectrometry (SIMS) ultra-shallow depth pro. ling. The effect of oxygen flooding pressure on the roughness development has been investigated under the bombardment of 500 eV O-2(+) beam with simultaneous sample rotation. Oxygen flooding had two competing effects on the surface roughening, i.e., enhancement of initiating roughening and suppression of roughening development, which were suggested to be described by the onset depth z(on) and transient width w(tr) of surface roughening. Both z(on) and w(tr) decreased as oxygen flooding pressure increased. As the result, surface roughening was most pronounced at the intermediate pressure from 4.4E-5 Pa to 5.8E-5 Pa. The surface roughening is negligible while without flooding or with flooding at the saturated pressure. No flooding is preferable for depth pro. ling ultra-shallow B implantation because of the better B pro. le shape and short analysis time. (C) 2008 Elsevier B. V. All rights reserved.