Through-Silicon-Via-Based Decoupling Capacitor Stacked Chip in 3-D-ICs

In this paper, a new decoupling capacitor stacked chip (DCSC) based on extra decoupling capacitors and through-silicon-vias (TSVs) is proposed to overcome the narrow-bandwidth limitation of the conventional decoupling capacitor solutions in three-dimensional-integrated circuits (3-D-ICs), as exhibited by expensive on-chip metal-oxide-semiconductor (MOS) decoupling capacitors and inductive off-chip discrete decoupling capacitors. In particular, in comparison to the on-chip decoupling solutions, such as MOS, metal-insulator-metal and deep trench capacitors, the proposed TSV-based DCSC represents several advantages, such as small leakage currents, large capacitances ranging from tens of nF to a few μF, low equivalent series inductance (ESL) with tens of pH, and high flexibility in TSV arrangements. The proposed TSV-based DCSC can be applied by mounting decoupling capacitors, such as Si-based MOS capacitors and discrete capacitors, on the backside of a chip and connecting the capacitors to the on-chip power delivery network (PDN) through TSVs. To demonstrate the performance of the proposed DCSC structure, a segmentation method was applied to compare the PDN impedance (Z11) of the TSV-based DCSC with those of the well-known conventional decoupling capacitor methods. The TSV-based DCSC was found to exhibit the advantages of both low on-chip level ESL (under several tens of pH) and high off-chip level capacitance (up to several μF). Additionally, the PDN impedance properties of the TSV-based DCSC were analyzed with respect to the variations in the number of power/ground TSV pairs, on-chip PDN size, and capacitance values of the stacked off-chip discrete decoupling capacitors using the segmentation method.