Advanced planar metallization with polymer for VLSI

An advanced planar metallization technology has been developed that makes use of PIQ^®(a polyimide type resin from Hitachi Chemical Co.). This technology employs a novel taper control etching approach for fine via holes, a sputter cleaning for low via hole contact resistance, and an A1 RIE for fine metallization patterning. Taper-controlled via holes in thick PIQ film satisfy demands for both minimizing via hole area and maintaining reliable step coverage in overlapping metallization at via hole steps. Appropriate sputter cleaning conditions accomplish low via hole contact resistance, eliminating undesirable influences on the polymer surface. Full use of RIE for both first and second metallization, in combination with taper control etching, provides 5 m pitch metallization. This technology, because of its excellent planarization and newly developed techniques, is shown to be applicable to highly packed multi-level interconnections for future VLSIs.