Three-dimensional integrated circuit (3D IC) with through-silicon-via (TSV) is believed to offer new levels of efficiency, power, performance, and form-factor advantages over the conventional 2D IC. However, 3D IC involves disruptive manufacturing technologies compared to conventional 2D IC. TSVs cause significant thermomechanical stress that may seriously affect performance, leakage, and reliability of circuits. In this paper, we discuss an efficient and accurate full-chip thermomechanical stress and reliability analysis tool as well as a design optimization methodology to alleviate mechanical reliability issues in 3D ICs. First, we analyze detailed thermomechanical stress induced by TSVs in conjunction with various associated structures such as landing pad and dielectric liner. Then, we explore and validate the linear superposition principle of stress tensors and demonstrate the accuracy of this method against detailed finite element analysis (FEA) simulations. Next, we apply this linear superposition method to full-chip stress simulation and a reliability metric named the von Mises yield criterion. Finally, we propose a design optimization methodology to mitigate the mechanical reliability problems in 3D ICs.
A major focus of the semiconductor industry in the last 45 decades has been to miniaturize ICs by advanced lithography patterning technology, which is now around 22 nm node. While ITRS still predicts further CMOS scaling, for example, to around 7 nm node by the year of 2020,7 such scaling will reach fundamental physical limit, or even before that happens, the economy of scaling will require other means for "more Moore" and "more than Moore" integration.
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