Thermal-driven placement in 3-dimensional integrated circuits.

摘要

Thermal distribution has become an important reliability concern for VLSI design, especially in the developing technology of 3-dimensional Integrated Circuits (3D ICs). In traditional design flows, the chip temperature is assumed to be uniform across the substrate. However, in reality integrated circuits have a non-uniform thermal distribution, which can be a major source of inaccuracy in timing calculation, and also in assessment of electromigration reliability. Thermal issue has been more prominent in 3D ICs. Ideally the physical design of ICs should yield a uniform temperature distribution so that the temperature gradient is negligible and there should not be any hot spots across the chip area. Uniform temperature distribution can be achieved by proper placement of circuit modules during physical design stages. At the same time, placement should also take into account other important factors such as the chip area, routing congestion and the timing closure issues. Microrefrigerators is another useful technique to remove the hot spot from the chip area. Therefore, the overall design process is a multi-objective optimization problem.; This research addresses multiple thermal-aware placement algorithms, such as partition-based algorithm and analytical approach. We developed a scalable compact substrate thermal model and integrate the thermal information on 3D ICs with conventional objectives mentioned above, in order to achieve a uniform on-chip thermal distribution. An efficient model for microrefrigerators is proposed to remove the hot spots when a well-managed placement process is still not enough to achieve uniform thermal distribution.