A Reliable Si₃N₄/Al₂O₃-HfO₂ Stack MIM Capacitor for High-Voltage Analog Applications

摘要

In this paper, we propose for the first time an attractive Si₃N₄/laminated Al₂O₃–HfO₂ (LAHO) stack metal–insulator–metal (MIM) capacitor with a low-leakage characteristic, good voltage linearity, high capacitance density, and excellent time-dependent dielectric breakdown (TDDB) reliability. The capacitor demonstrates a capacitance density of 4.2 fF/ (mu ) m (^{mathrm {mathbf {2}}}) , quadratic voltage coefficients ( (alpha ) ) of 106 ppm/V (^{mathrm {mathbf {2}}}) , and 18.92-year TDDB lifetime under a stressing voltage of 6.6 V. For the extended performance, it is projected that such a capacitor can possess a maximum capacitance density of 4.13 fF/ (mu ) m (^{mathrm {mathbf {2}}}) with (alpha le 100) ppm/V (^{mathrm {mathbf {2}}}) and TDDB lifetime of 10 years under an analog operation of 7 V. Furthermore, this paper shows that (alpha ) and TDDB lifetime of the new capacitor are very sensitive to the thickness of the Si₃N₄ film. Comparison of the new MIM capacitors with the SiO₂/HfO₂ stack MIM capacitors shows that the SiO₂/HfO₂ capacitor is more suitable for low-voltage applications, whereas the new Si₃N₄/LAHO capacitor is superior for operations requir- ng a higher biasing condition.