Tier Adaptive Body Biasing: A Post-Silicon Tuning Method to Minimize Clock Skew Variations in 3-D ICs

In this paper, we analyze the variability in a 3-D clock network designed with single and multiple through-silicon vias and present a post-silicon tuning methodology, called tier adaptive body biasing (TABB), to reduce skew and data path variability in 3-D clock trees. TABB uses specialized on-die sensors to independently detect the process corners of n-channel metal-oxide-semiconductor (nMOS) and p-channel metal-oxide-semiconductor (pMOS) devices and accordingly tune the body biases of nMOS/pMOS devices to reduce the clock skew variability. We also present the system architecture of TABB and circuit techniques for the on-die sensors. Circuit-level simulation and statistical analysis of the TABB architecture in a predictive 45-nm technology demonstrate the effectiveness of TABB in reducing the clock skew variability considering the data path variability in 3-D ICs.