DIFFUSION ISOLATION LAYER FOR MASKLESS CLADDING PROCESS

• Main Authors: ANANDA HOSAKERE KUMAR, LESTER WYNN HERRON
• Format: Patent
• Language: English
• Published: 13.08.1986
• Edition: 4
• Subjects: BASIC ELECTRIC ELEMENTS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; DIFFUSION TREATMENT OF METALLIC MATERIAL; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS; METALLURGY; PRINTED CIRCUITS; SEMICONDUCTOR DEVICES; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION

In a maskless metal cladding process for plating an existing metallurgical pattern (13), a protective layer (16) is utilized to isolate those areas of underlying metallurgy on which additional metal plating is not desired. The layer acts as an isolation barrier to protect the underlying metallurgy from deposition and subsequent diffusion of the heavy metal overlay (17). The composition of the protective layer is selected as one having sufficient mechanical integrity to withstand process handling and support the gold overlay and having the thermal integrity to withstand the high temperatures reached during metal sputtering and diffusion processes. The isolation barrier layer has an organic component as a binder which thermally decomposes, either in a heating step before metal deposition or during the diffusion cycle, leaving no carbonaceous residue but leaving an inert, inorganic standoff to support the metal. After diffusion of the metal, the remaining inorganic standoff layer, overlying metal and any undiffused metal remaining on the non-patterned substrate is easily removed by a standard technique, such as ultrasonics.