Robust process windows for Laser Induced Forward Transfer of thin film metal to create inter connects

Direct-write technologies can form a low-cost, alternative approach to create electrical interconnects by eliminating mask and etch costs. Also, direct-write is more efficient in creating complex structures as well as for producing small series. However, existing, industrially-mature direct-write technologies typically lack the resolution required for advanced IC packaging applications [1–4]. Laser Induced Forward Transfer (LIFT) is a direct write process which has been proven to be capable of patterning resolutions in the 1–5 μm range [5–8]. Thus far, a lack of deposition control resulting in contamination of the substrate has been a problem. The current paper shows an approach to come to a robust, contamination-free process window for LIFT of pure copper. Thus, we tackled a major roadblock towards the industrial feasibility of LIFT as a full metal direct-write technology that meets the current demands for IC packaging and integration.