Revisiting 3DIC Benefit with Multiple Tiers

Abstract

3DICs with multiple tiers are expected to achieve large benefits (e.g., in terms of power, area) as compared to conventional planar designs. However, few if any previous works study upper bounds on power and area benefits from 3DIC integration with multiple tiers. In this work, we use the concept of implementation with infinite dimension to estimate the upper bound of power and area benefit from 3DICs. We observe that the maximum power benefit evaluated with infinite dimension is only 18% for particular designs. Such benefits further reduce under the assumption of inter-tier variation. In addition, we study power of designs across various dimensions (e.g., pseudo-1D, 2D, 3D with two, three and four tiers).1 We observe that design power sensitivity to implementation with different dimensions correlates well with placement-based Rent parameter of the netlist. Therefore, placement-based Rent parameter can possibly be a simple indicator of 3D power benefit. Our study also shows that netlist synthesis and optimization should be aware of the target implementation dimension (e.g., 2D versus 3D).