Abstract: A process for producing an etched structure in a surface of a solid body by providing a mask on the surface of the solid body to expose the desired portions of the surface, ionic etching the mask and the exposed surface with the material of the mask and the material of the solid body being disintegrated and removed by the ion bombardment of the ionic etching characterized by the disintegration rate of the mask being changed during the ionic etching step. In one embodiment of the process the mask is composed of at least two layers having different disintegration rates with the layer having the highest disintegration rate being disposed adjacent the surface and the layer with the lower disintegration being disposed thereon. In another embodiment of the invention, the mask comprises a single layer of material, such as metal, and the rate of disintegration of the masking layer is changed by adding a reactive gas during a portion of the ionic etching step.