Effectiveness of a Guard Ring Utilizing an Inversion Layer Surrounding a Through Silicon Via

We characterize quantitatively a guard ring of a through-silicon via (TSV) which is used to reduce the coupling noise from the TSV by utilizing an inversion layer as a shield layer. The proposed guard ring consists of a shallow n⁺ region, a deep n^- well, and an inversion layer formed along the interface between the oxide surrounding the TSV and the p-substrate. The coupling noise induced by the TSV is reduced by approximately one order of magnitude in the near-threshold region of the victim nMOS, which is located at 10 μm away from the TSV. The proposed guard ring is characterized as the distance between the TSV and the victim nMOS in a comparison with cases without a guard ring and with a conventional p⁺ guard ring. The proposed method reduces the drain current fluctuation by ~61% compared with the case with the conventional p⁺ guard ring.