A method and apparatus for calibrating a semi-empirical process simulator used to determine process values in a plasma process for creating a desired surface profile on a process substrate includes providing a test model which captures all mechanisms responsible for profile evolution in terms of a set of unknown surface parameters. A set Sets of test conditions processes is are derived for which the profile evolution is governed by only a limited number of parameters. For each set of test conditions process, model test values are selected and a test substrate is substrates are actually subjected to a the test process processes defined by the test values , thereby creating a test surface profile profiles. The test values are used to generate an approximate profile prediction predictions and are adjusted to minimize the discrepancy between the test surface profile profiles and the approximate profile prediction predictions, thereby providing a final model of the profile evolution in terms of the process values.