Process for defined etching of substrates

A process for making a pattern of one or more etched features in a substrate which comprises the steps:

• (a) applying diffusion transfer nuclei to a surface portion of the substrate,
• (b) applying a silver halide containing photosensitive material either as a layer on the substrate overlying the diffusion transfer nuclei or as a layer on a second substrate,
• (c) exposing the photosensitive material to actinic radiation in a pattern corresponding to the desired etch pattern,
• (d) applying developer solution to material exposed in Step (c),
• (e) forming a pattern of silver as a coating on the substrate by silver diffusion transfer wherein the pattern has no developed silver in the areas to be etched,
• (f) removing the layer that originally contained the silver halide material while leaving the pattern of silver formed in Step (e) on the surface of the substrate, and
• (g) applying an etching treatment to remove the substrate in the areas not covered by silver thereby forming an etched pattern.