Milling a multi-layered object

A miller, a non-transitory computer readable medium, and a method for milling a multi-layered object. The method may include (i) receiving or determining milling parameters related to a milling process, the milling parameters may include at least two out of (a) a defocus strength, (b) a duration of the milling process, (c) a bias voltage supplied to an objective lens during the milling process, (d) an ion beam energy, and (e) an ion beam current density, and (ii) forming a crater by applying the milling process while maintaining the milling parameters, wherein the applying of the milling process includes directing a defocused ion beam on the multi-layered object.