Using Outlier Control Technology with Feedforward Lithography to Address Die Shifting and Pattern Distortion Challenges in Fan-Out Panel-Level Packaging

Abstract

Fan-out panel-level packaging (FOPLP) is a packaging technology able to meet the requirements of heterogeneous integration while reducing costs for manufacturers. However, FOPLP faces several significant process challenges. One of these is die shifting, which is a result of the reconstitution process in die-first FOPLP. Pattern distortion is another challenge, one caused by panel deformation in redistribution layer-first FOPLP. These issues cause die and patterns to move away from their nominal positions. If die shifting and pattern distortion are not well addressed during the lithography process, they will result in overlay errors and low overlay yield. Outlier control technology with feedforward lithography is proposed to address these die-shifting and pattern-distortion challenges. Outlier control is based on site-by-site corrections and uses an algorithm to recognize outliers in the substrate, eliminate their negative impacts and optimize overlay corrections to ensure good overlay yield. Additionally, feedforward lithography can further reduce the negative impact to throughput caused by the time lost addressing site-by-site corrections. In this study, we will discuss how die shifting and pattern distortion result in yield and throughput challenges for FOPLP. Then we will demonstrate outlier control technology with feedforward lithography on a test vehicle and how the integration of these two technologies addresses the challenges. We will also review the results of the demonstration and discuss the advantages of this strategy.