METHOD OF MAKING TWO MOS STRUCTURES WITH DIFFERENT CONTIGUOUSLY PLACED DIELECTRICS AND DIFFERENT DOPING CONCENTRATIONS, AND CHARGE TRANSFER MATRIX MADE BY THIS METHOD

摘要

The process of the invention consists in depositing a doped polycrystalline silicon layer on a silica dielectric which isolates it from the substrate. By photolithographic etching zones are defined which are intended to undergo ionic implantation for the buried channel, the zones to be protected being masked by the remaining silicon. A double silica-nitride layer is formed after the substrate has been bared in the implanted regions; Photolithographic etching of the double silica-nitride layer gives access to the first silicon level of a second doped silicon layer. Photoetching of the whole of the two silicons allows different structures to be formed in which for example the transition zone between the two dielectrics is situated under the same gate or else in which for example the transition zone is self aligned with a gate.