Bidirectional transient voltage suppression diodes for the protection of high speed data line from electrostatic discharge shocks

A bidirectional transient voltage suppression (TVS) diode consisting of specially designed p^-n⁺⁺-p^- multi-junctions was developed using low temperature (LT) epitaxy and fabrication processes. Its electrostatic discharge (ESD) performance was investigated using IV, C-V, and various ESD tests including the human body model (HBM), machine model (MM) and IEC 61000-4-2 (IEC) analysis. The symmetrical structure with very sharp and uniform bidirectional multijunctions yields good symmetrical I-V behavior over a wide range of operating temperature of 300 K - 450 K and low capacitance as 6.9 pF at 1 MHz. In addition, a very thin and heavily doped n⁺⁺ layer enabled I-V curves steep rise after breakdown without snapback phenomenon, then resulted in small dynamic resistance as 0.2 Ω, and leakage current completely suppressed down to pA. Manufactured bidirectional TVS diodes were capable of withstanding ± 4.0 kV of MM and ± 14 kV of IEC, and exceeding ± 8 kV of HBM, while maintaining reliable I-V characteristics. Such an excellent ESD performance of low capacitance and dynamic resistance is attributed to the abruptness and very unique profiles designed very precisely in p^-n⁺⁺p^- multi-junctions.