A Dual-Direction SCR Featuring Shallow Snapback and High-Temperature Robustness for ESD Protection of Industrial Communication Buses

The reliability standards for on-chip electrostatic discharge (ESD) protection in high-voltage industrial communication buses are stringent, and traditional ESD solutions cannot effectively meet the requirements for high holding voltage ( ${V} _{h}$ ) and high-temperature tolerance in these applications. Therefore, this article presents a dual-direction silicon-controlled rectifier (DDSCR) featuring shallow snapback and high-temperature robustness. At the same size, ${V} _{h}$ (38.4 V) of the parallel NPN-enhanced SCR (NPNE_DDSCR), which employs a metal short and no shallow trench isolation (STI), is significantly higher than that of the traditional structure (T_DDSCR) and the parallel NPN structure (NPN_DDSCR). Under high-temperature conditions ranging from $50~^{\circ }$ C to $125~^{\circ }$ C, the structure maintains nanoampere-level leakage current, and the device’s ESD characteristics show no significant degradation. The electrostatic properties of three types of structures were verified based on the 0.18- $\mu $ m bipolar-CMOS–DMOS (BCD) process, and their operating mechanisms were further analyzed using technology computer-aided design (TCAD) simulations. The results show that the NPNE_DDSCR exhibits superior performance, with a human body model (HBM) level exceeding 8 kV, and is suitable for efficient on-chip ESD protection of industrial communication buses.