Photosensitive Polyimide as a Dielectric in High Density Thin Film Copper‐Polyimide Interconnect Structures

Abstract

A photosensitive polyimide is evaluated as a dielectric material in high density thin film copper‐polyimide interconnect structures. Factors affecting the photolithographic fabrication of structures with small feature size and high aspect ratio have been investigated. The shrinkage characteristics of the precursor film were observed to depend strongly on the UV exposure conditions. Dimensional changes taking place during curing of the polyimide structures show anisotropic shrinkage, the degree of which depends upon the feature size. The photosensitive polyimide precursor is observed to interact strongly with copper and results in residue formation during patterning. Based on this photosensitive polyimide process, high density thin film copper‐polyimide interconnect structures with wiring density close to 800 lines per centimeter were fabricated.