Multi-level metallurgy for master image structured logic

A dense double-level metal interconnection process has been developed for application to master image structured logic products. The metal wiring pitches that are currently being produced, 5.0-µm metal 1 and 7.0-µm metal 2, are compatible with 2.0-µm lithography at other mask levels. These densities are achieved by use of a nitride-polyimide dual insulation scheme and second metal lift-off to achieve a unique overlapping via structure and elimination of metal borders. Details and rationale for the choice of the insulator/via etch scheme and second metal definition process are discussed. Finally, the influence of various topographical effects are also considered.