An optimal stacking order for mid-bond testing cost reductionof 3D IC

In order to solve the problem that the testing cost of the three-dimensional integrated circuit(3D IC)is too high, an optimal stacking order scheme is proposed to reduce the mid-bond test cost. A new testing model is built with the general consideration of both the test time for automatic test equipment(ATE)and manufacturing failure factors. An algorithm for testing cost and testing order optimization is proposed, and the minimum testing cost and optimized stacking order can be carried out by taking testing bandwidth and testing power as constraints. To prove the influence of the optimal stacking order on testing costs, two baselines stacked in sequential either in pyramid type or in inverted pyramid type are compared. Based on the benchmarks from ITC’02, experimental results show that for a 5-layer 3D IC, under different constraints, the optimal stacking order can reduce the test costs on average by 13% and 62%, respectively, compared to the pyramid type and inverted pyramid type. Furthermore, with the increase of the stack size, the test costs of the optimized stack order can be decreased.