Argon- ion implantation can be used to selectively and dramatically enhance the etch rate of a silicon dioxide film down to a precise depth, to allow for improved control of etch depth in a timed oxide etch process. An empirical model based on damage concentration, fit to experimental data, is used to explain the correlation between the implantation conditions (dose, energy) and the etch- rate enhancement parameters. The model is shown to yield predictions of the etch rate enhancement consistent with the existing model based on nuclear deposited energy. The depth of etch- rate enhancement is determined primarily by the implant energy, whereas the etch- rate enhancement factor is controlled by the implant dose. Enhancement factors close to five were achieved with moderate- dose (2 x 10(14)/ cm(2)) Ar+ implantation. Lower ion- implantation energy results in sharper transition between the etch- rate enhanced and the unaffected oxide region. This technique can be used to improve process uniformity in fabrication of three- dimensional semiconductor device structures such as bulk- Si FinFETs, for reduced variations in circuit performance. (c) 2007 The Electrochemical Society.