Shave-off depth profiling, our own unique technique, utilizes a focused ion beam (FIB) micro-machining process to provide the depth profile. It is known that the FIB has long tails outside of the beam. The long tails affect the shape of depth profile and make depth resolution worse. The influence of long tails can be minimized by depositing a protection film on the sidewall or changing the speed of shave-off scan. In this study, we discussed about shave-off scanning speed toward depth direction by using simulation method and accomplished highly accurate shave-off depth profiling. (C) 2008 Elsevier B.V. All rights reserved.