The image opposite demonstrates the effects of Gas Assisted Etching (GAE). The image shows an integrated circuit that has been etched over a large area using XeF2. By using GAE, the dielectric has been preferentially milled with most of it being cleared away by the XeF2. XeF2 removes dielectrics at a greatly enhanced rate compared to conventional milling, and allows a great deal of dielectric to be removed with a minimum dose from the FIB's beam. With a greatly reduced dose, the metal lines (for which milling is not enhanced by the XeF2) show minimal sputter.