This study aims to present a comprehensive investigation into the role of fluorine in enhancing the performance and reliability of P+ doped silicon Zener diodes through a systematic comparison of boron (B11) and boron difluoride (BF2) implantation techniques.
By analyzing the electrical characteristics, current–voltage (I-V) measurements were performed on 52 samples of Zener diode on wafer level at temperatures of −40 °C, 25 °C and 125 °C. For reliability characteristics, the Zener diode was stressed at 175 °C with an 80 µA in the reverse bias for 14 h, and the Zener voltage values were monitored every second during stressing. Parameters such as breakdown voltage, reverse leakage current, dynamic resistance, forward voltage and ideality factor were extracted from I-V measurement to assess the performance enhancements enabled by fluorine implantation.
BF2-implanted Zener diodes exhibit superior electrical characteristics, including a 45.8% reduction in dynamic resistance, a 52.3% suppression of reverse leakage current and a higher Zener voltage compared to conventional boron-implanted devices at room temperature. Notably, BF2 implantation significantly improves operational stability, evidenced by a lower temperature coefficient of Zener current and enhanced forward voltage characteristics. Advanced stress dependence analysis reveals that fluorine incorporation mitigates leakage current drift and Zener voltage instability under prolonged electrical stress, attributed the trapping of electrons by fluorine ions in the depletion region.
This research highlights the effectiveness of BF2 implant instead of B11 implant contribute to the improvement of tunneling effect and reliability of the Zener diode. Nevertheless, the development of a novel technique for the fabrication of Zener diode which has advantages over the conventional P+ doped techniques is studied.
