Test-architecture optimization for TSV-based 3D stacked ICs

Testing of 3D stacked ICs (SICs) is becoming increasingly important in the semiconductor industry. In this paper, we address the problem of test architecture optimization for 3D stacked ICs implemented using Through-Silicon Vias (TSVs) technology. We consider 3D-SICs with both fixed given and yet-to-be-designed test architectures on each die and show that both corresponding problem variants are NP-hard. We next present mathematical programming techniques to derive optimal solutions for these problems. Experimental results for three handcrafted 3D-SICs of various SOCs from the ITC'02 SOC test benchmarks show that compared to the baseline method of sequentially testing all dies in a stack, the proposed solutions can achieve up to a 57% reduction in test time. We also show that increasing the number of test pins provides a greater reduction in test time compared to an increase in the number of TSVs. Furthermore, it is shown that 3D stacks with large and complex dies at lower layers require less test time than stacks with complex dies at higher layers.