Advanced Stepper Through-Silicon Alignment (TSA) Evaluation and Overlay of Distorted Bonded Wafer Stacks

Abstract

Canon Litho Products support Vertical Lithography challenges required by TSV and advanced packaging applications that support “More-than-Moore” advancements. Vertical Lithography challenges include accurately performing backside, infrared alignment to distorted bonded-wafer grids and imaging through thick resist films. This paper will provide examples illustrating severe wafer distortion that can be experienced after wafer thinning and the impact of overlay and imaging control. This paper will also introduce Canon stepper features that are designed to address Vertical Lithography challenges including the Canon Through-Silicon Alignment (TSA) System and advanced Projection Lens. Grid distortion characterization data and stepper compensation results are presented to illustrate Canon stepper technology performance under severe process conditions.