Test-Point Insertion for Power-Safe Testing of Monolithic 3D ICs using Reinforcement Learning*

Monolithic 3D (M3D) integration for integrated circuits (ICs) offers the promise of higher performance and lower power consumption over stacked-3D ICs. However, M3D suffers from large power supply noise (PSN) in the power distribution network due to high current demand and long conduction paths from voltage sources to local receivers. Excessive switching activities during the capture cycles in at-speed delay testing exacerbate the PSN-induced voltage droop problem. Therefore, PSN reduction is necessary for M3D ICs during testing to prevent the failure of good chips on the tester (i.e., yield loss). In this paper, we first develop an analysis flow for M3D designs to compute the PSN-induced voltage droop. Based on the analysis results, we extract the test patterns that are likely to cause yield loss. Next, we propose a reinforcement learning (RL)-based framework to insert test points and generate low-switching patterns that help in mitigating PSN without degrading the test coverage. Simulation results for benchmark M3D designs demonstrate the effectiveness of the proposed power-safe testing approach, compared to baseline cases that utilize commercial tools.