Digitally driven maskless lithography optimized for fine pitch RDL and next generation devices

Improved performance and package form factors are shifting traditional designs toward higher density and 3D vertical integration concepts. The introduction of finer RDL lines/spacings provides higher performance but reduces the options for integration and electrification design rules at the package and substrate levels due to potential parasitic electrical effects. In this work, we evaluate high-performance chemically enhanced positive-tone photoresists tailored for high-resolution fine-pitch RDL and μ-bump/μ-pillar fabrication to achieve high aspect ratios and employ maskless exposure to demonstrate their patterning performance. Resolution testing, focus position, and exposure matrices, including resist sidewall profiles, are discussed with respect to 2/2μm line/space (L/S) requirements and beyond for heterogeneous integration designs.