Advanced Lithography Solutions to Address Extreme Die Shifts in Fan-Out Panel-Level Packaging

Fan-out panel-level packaging (FOPLP) is among the most effective solutions for meeting the demands of 2.5D packaging while also reducing costs. Nevertheless, FOPLP encounters several critical process challenges. A primary issue is die shifting, which arises from the reconstitution process in die-first FOPLP. These complications lead to the displacement of dies from their intended positions. If die shifting is not adequately recognized and addressed during the lithography process, it can cause substantial overlay errors and significantly reduce overlay yield. To address the challenges of die shifting, a novel lithography solution has been proposed: outlier control technology integrated with feedforward lithography. This advanced technique involves a site-by-site (SBS) correction method facilitated by an algorithm that identifies outliers on the substrate. The algorithm optimizes overlay corrections to eliminate the side effects of these outliers, thereby ensuring high overlay yield. Moreover, feedforward lithography mitigates the impact on throughput caused by the time-intensive SBS corrections required by outlier control technology. In this study, we will examine the impact of die shifting on overlay yield in FOPLP and explore how outlier control technology combined with feedforward lithography addresses the associated yield and throughput challenges. We will demonstrate the application of these technologies on a test vehicle, a 510mm x 515mm panel containing 400 dies, with some dies intentionally displaced from their nominal positions. The test vehicle will be processed using advanced outlier control technology in conjunction with feedforward lithography. This demonstration will illustrate the integration of these technologies and how this strategy effectively addresses the identified challenges. Additionally, we will review the demonstration results and discuss the advantages of this integrated approach.