Dummy Features in Redistribution Layers for Fan-Out Packaging

The redistribution layer structure is divided into multiple separate metallization patterns (first, second, third metallization patterns) stacked at different heights, with each layer performing specific routing functions. This segmentation allows complex I/O redistribution to be achieved through modular layers, improving packaging density while managing complexity through systematic layering.

The patent utilizes vertical stacking of metallization patterns at different heights (first height, second height, third height) to achieve three-dimensional I/O redistribution. By adding the vertical dimension, the design redistributes I/O pads in multiple layers rather than relying solely on planar expansion, thereby increasing packaging density without proportionally increasing manufacturing complexity.

Dummy patterns are strategically positioned between the first and second metallization patterns, and between the second and third metallization patterns, to provide stress relief and planarity compensation before manufacturing defects can occur. These dummy structures act as preventive measures, cushioning against potential manufacturing failures by compensating for stress accumulation and surface irregularities in advance.

The dummy patterns are selectively placed in specific locations where stress concentration or planarity issues are anticipated, rather than uniformly distributing them across the entire structure. This localized approach improves reliability at critical points while minimizing the overall increase in device complexity.