Operating TSV in stable accumulation capacitance region by utilizing Al2O3-induced negative fixed charge

Abstract

The variation of through-silicon-via (TSV) capacitance caused by nonuniform hot-spot heating can lead to spatial circuit performance variation; this effect is undesirable for 3-D IC design. Hence, stable TSV capacitance is desired to overcome this issue. In this letter, stable TSV capacitance is achieved by utilizing Al2O3-induced negative fixed charge (|Qf| = 7.44 × 1011 cm-2) at the Si-liner interface. This causes a positive shift in the flat-band voltage (ΔVFB = 6.85 V) and results in the TSV operating in the stable accumulation capacitance region within operating voltage of interests (~0-5 V). The leakage current density of the TSV with Al2O3 layer and PETEOS liner is improved by ~10× after annealing in forming gas (N2/H2) at 300 °C for 30 min.