Novel Process of RDL Formation for Advanced Packaging by Excimer Laser Ablation

Abstract

The continuous trend in miniaturization, increasing performance and mobility of electronic devices drives not only the requirements of the chip itself, but also its package type. The current integration processes encompassing photolithography may be reaching their capability limits for developing cost effective and innovative package designs to meet the market's most stringent requirements. In addition, there are significant challenges in these legacy processes that manufactures will need to overcome. In support of this technology trend and to address the current photolithography process integration challenges, we introduce excimer laser ablation as a direct patterning process that uses proven industrialized excimer laser sources to emit high-energy pulses at short wavelengths to remove materials. The combination of a high-power excimer laser source, large-field laser mask and precision projection optics enables the accurate replication and placement of fine resolution circuit patterns without the need for any wet-processing. In addition, with excimer laser patterning technology the industry gains a much wider choice of dielectric materials (photo and non-photo) to help achieve further reductions in manufacturing costs as well as enhancements in chip or package performance. In this paper, we propose a new process based on the front-end-of-line (FEOL) dual damascene integration flow for building multilayer embedded RDL for Advanced Packaging. The new process uses excimer laser ablation to integrate via and RDL traces in one patterning process step, followed by seed layer deposition, plating and planarization processes. We will explain in detail the new proposed integration flow and further demonstrate its technical robustness and commercial advantages. We will also cover the capability of this excimer laser process to extend the current material portfolio to non-photo materials and highlight its commercial benefits as compared to the current process of record (POR).