Micro-LED Driving Backplane Via Pillars Without Substrate Stress

The patent segments the conductive pillar formation process into multiple stages with different deposition methods. First, a seed layer is formed, then an intermediate layer, and finally the copper pillar is completed. This segmentation allows stress management by using different materials and deposition techniques at different stages, preventing substrate breakage while achieving precise conductive pillar formation.

The patent employs composite material structures for conductive pillars, using combinations of different materials (such as tungsten, copper, and other conductive materials) in layered configurations. This composite approach distributes internal stress across different material layers with different mechanical properties, preventing substrate failure while maintaining electrical conductivity.

The patent extracts or removes the chemical mechanical polishing step from the manufacturing process entirely. Instead of polishing the flexible base, the method uses alternative approaches such as controlling the deposition process or using different surface treatment methods that achieve the required surface flatness without applying the mechanical and chemical stresses that damage the flexible base.

The patent introduces a removable mask layer that serves as a sacrificial element during the via formation process. This mask layer protects the flexible base during processing, allowing precise via formation without directly damaging the flexible base. The mask is later removed, having served its protective function temporarily.