step consists of exposing certain areas defined by a mask pattern of the resist layer on the substrate 5 to a beam of light of which the energy is able to chemically alter all of the exposed areas of the resist layer so as to make them soluble in a suitable solvent if the projected image 8 does not cover almost the entire substrate 5 this step is repeated as many times as desired by moving the support 15 to reposition the wafer with respect to the projected light beam 6 in general alignment marks are provided in the mask pattern to allow successively projected patterns to be aligned with each other the wafer may then be heated to harden the non exposed resist and thus obtain straight profiles after a development step in a third fabrication step the resist of the wafer is placed in contact with a solvent that dissolves the zones that were exposed to the energy of the light beam 6 the solvent may be deposited on resist at the center of the wafer that is rotated about its axis so as to cover the entire resist layer the wafer is then rinsed in water and then dried it may also be heated to harden the remaining resist and to give it a resistance so that it is capable of withstanding an etching or implantation operation it should be noted that in certain methods implementing other types of photosensitive resists and other solvents it is on the contrary the zones exposed to the light beam that become insoluble to the solvent used during the development step in this case the.