Process for metallized vias in polyimide

Claim 1

A process for producing a plurality of metallized vias in a polyimide layer on a substrate comprising the steps of: (a) applying a solution of a polyimide precursor in an inert solvent to said substrate; (b) heating, in a first heating cycle, said solution of polyimide precursor at a combination of temperature and pressure sufficient to volatilize said inert solvent but insufficient to completely convert said polyimide precursor to polyimide; and continuing said first heating cycle for a period of time at least sufficient to provide a mechanically stable layer; (c) applying a solution containing a polyaminoalkylalkoxysilane (PAAS) in an inert, nonaqueous solvent to said mechanically stable layer of polyimide precursor; (d) heating, in a second heating cycle, said solution of a PAAS at a combination of temperature and pressure sufficient to volatilize said inert solvent but insufficient to completely imidize said polyimide precursor and insufficient to cleave a significant portion of amino functions in said PAAS, and continuing said second heating cycle for a period of time at least sufficient to provide a mechanically stable silane layer; (e) patterning both of said layers of polyimide precursor and silane with a plurality of trenches; (f) depositing sufficient metal on said substrate to at least fill said trenches; (g) heating, in a third heating cycle, said metal, said silane layer and said polyimide precursor layer at a temperature and for a time sufficient to completely imidize said polyimide and to convert said silane layer to a silsesquioxane polymer layer; and (h) chemical-mechanical polishing said substrate to remove all of said metal outside said trenches using said layer of silsesquioxane as a polish stop.