Submicron Lithography Enabling Panel Based Heterogeneous Integration

Abstract

High-Performance Computing (HPC) systems increasingly adopt Heterogeneous Integration (HI) technologies that utilize large substrates and high-resolution processes to facilitate die and chiplet. Fan-Out Wafer Level Packaging (FOWLP) and silicon interposers using high-density Redistribution Layers (RDL) can help maximize bandwidth and performance but HI roadmaps require improvements in resolution and lower costs to enable wide adoption of these More-than-Moore technologies. Panel based processes can provide cost advantages compared to wafer processes for fabrication of large interposers and Fan-Out packages. Panel based SiP processes however demand submicron resolution over a large field size and uniform exposure across large panels. To meet these challenges, Canon developed the first lithography exposure system capable of achieving submicron resolution on large panels. The new panel exposure tool targets 0.8 μm design rules and utilizes a new panel handling system and stage that allows processing of panels as large as 515 × 515 mm. The new panel exposure tool is equipped with a UL82 wide-field projection lens with a maximum Numerical Aperture (NA) of 0.24 and offers a 52 × 68 mm exposure field for large device fabrication without stitching adjacent shots. Fine-RDL lithography systems must provide a large Depth-of-Focus (DoF) to maintain pattern fidelity to maximize DoF, the new panel exposure tool applies die-by-die focus and tilt compensation and functions to compensate for panel warpage. Process factors related to DoF include panel flatness and photoresist materials and film uniformity. This paper details test results from a panel exposure system that confirms the feasibility and advantages of submicron panel processes. We also introduce additional challenges related to panel processes including slit-coater uniformity, photo resist materials and panel flatness. We will present data illustrating that new panel exposure tool can provide excellent resolution across large exposure fields on panels to enable HI innovation.