High wiring density Cu-polyimide thin film multilayer circuit which is realized by the vertical plated small via

A fabrication process for Cu-polyimide thin film multilayer circuit has been developed for advanced multichip module. The multilayer circuit realizes a high wiring density circuit by applying Cu studs which are deposited by electroplating using the guide patterns made of thick positive photoresist, photosensitive polyimide for insulating layers which has low reactivity against Cu, and a polishing process for planarizing dielectric layers. This paper reports on the structure of the circuit and on the thin film process technology.