2/2um Embedded Fine Line Technology for Organics Interposer Applications

The requirement of IC packages with fine line features has increased significantly. Semi-Additive Process (SAP) is the traditional way to make copper trace in the organic substrate. However, inadequate adhesion of fine line to dielectric materials occurred in manufacturing for line/space less than 5/5μm. Line embedded (LE) is another way to form fine circuitry. LE technology has several advantages such as good adhesion between fine copper features to the dielectric materials due to embedding. It has a better electric performance with a smaller variation of trench width and depth. It also provides a better design flexibility for a pad-less features and a higher reliability than the SAP process due to the complete removal of seed layer. In this paper, an innovative fine line embedded composite dielectric structure was proposed. The process to fabricate a three-layer structure with fine embedded trench with features less than 2/2μm was demonstrated. Embedded trench was made by lithography of the photosensitive dielectric material with high resolution. The interconnecting via was then formed by laser drilling on the organic build-up dielectric layer with fine fillers. Copper damascene of copper reduction process was used to obtain a well controlled copper over-burden removal. The copper over-etching amount can be controlled to less than 0.5μm. In summary, an innovative three-layer embedded fine line copper trace in a composite dielectric structure was successfully demonstrate.