My previous post gave an overview of the new Applied Nokota™ ECD system for wafer-level packaging (WLP). In this post I’ll explain how the system helps solve some of the major challenges for chip manufacturers, foundries and OSATs as they strive to cost effectively manufacture a variety of advanced packages that meet specific requirements for a growing number of mobile and high-performance computing applications.
In electrochemical deposition (ECD), wafers must be sealed for protection during the plating sequence to prevent plating on the backside of the wafer. This requirement led us to develop the SafeSeal™ assembly that ensures ultimate protection for every wafer, sealing each one prior to processing and protecting it throughout a single- or multi-metal plating sequence. Automated pre-process seal leak testing and post-process cleaning, inspection and validation ensure every wafer is properly sealed and protected before the plating sequence begins. Sealing the wafer only once for processing eliminates time-consuming sealing and unsealing steps typically needed at each process chamber. It also removes the risk that a seal will leak during one of the resealing events. Using a known good seal for the entire sequence protects high-revenue wafers from scrap events in the final stages of production and increases throughput of multi-metal processes.
In conjunction with the SafeSeal integrity tests, the Nokota system’s new HotSwap™ mechanism that operates in parallel outside the plating chambers automatically replaces flagged SafeSeal wafer assembly units without interrupting production. This helps improve productivity and eliminates unscheduled and scheduled chamber downtime for seal maintenance, inspection or cleaning, making more hours available for production.
Specially designed VMax™ plating chambers promote maximum mass transfer control for producing optimal co-planarity at high plating rates, delivering superior on-wafer performance and high productivity. An in-chamber, integrated clean for immediate post-process wafer rinsing ensures the purity of each successive metal in a multi-metal plating sequence and prevents oxidation of the wafer prior to final rinse/dry.
With the growing variety of WLP schemes (Bump/Pillar, Fan-Out, TSV and more) that are also becoming more complex, enabling manufacturers to quickly transition among them is crucial. Specially engineered with high-reliability components, the modular Nokota system allows for quick, in-fab reconfiguration between different process flows. This rapid (<1 day) reconfiguration and unique, flexible single-chamber configurability (vs. the typical chamber pairs) makes the Nokota system ideal for handling varying product mixes and capacity demands. Further, the system’s modularity makes it easily extendible from R&D through pilot production to high-volume manufacturing.