A novel robust SCR with high holding voltage for on-chip ESD protection of industry-level bus

In an industry-level bus, strong electrostatic interference seriously threatens the reliability of chips. However, the holding voltage (Vh) and robustness of traditional silicon-controlled rectifier (SCR) cannot meet the electrostatic discharge (ESD) window of industry-level applications. To better cope with extreme environments, this paper proposes a novel SCR with high robustness and latch-up immunity for on-chip ESD protection of the industrylevel RS485 bus. By incorporating a surface current diverting path into the traditional SCR, the ESD characteristics of the proposed device are significantly improved. Through two-dimensional device simulation, the ESD characteristics of traditional SCR, proposed P-Well Floating SCR (PFSCR) and proposed P-Well Grounded SCR (PGSCR) are compared, with a focus on exploring the role of surface discharge path. Three types of SCR are realized based on the 0.18 & mu;m BCD process. The transmission line pulse (TLP) test results show that PGSCR (13.64 V) has a higher Vh and higher robustness than traditional SCR (2.13 V) and PFSCR (4.39 V). In addition, the trigger voltage (Vt1:22.9 V) and failure current (It2:18.49A) of the PGSCR fully meet the ESD window of the target chip.