Rotary spare replacement redundancy for tree architecture WSIs

The author proposes rotary spare replacement redundancy (RSRR) for defect tolerance in tree architecture WSIs. The main feature of the RSRR is that it can be applied in element groups of a subroot element and its leaf elements on every neighboring two stages, using a simple switching scheme based on k-out-of-n redundancy. Especially, it can be applied to hierarchical redundancy, which is advantageous in terms of spare effectiveness, redundancy coverage, and replacement control simplicity. The effectiveness of the proposed redundancy is demonstrated through estimates based on the design of an eight-stage binary tree merger WSI (wafer scale integration) with a three-level hierarchical redundancy configuration