Low Capacitance and Fast Response SCR for High-Speed I/O ESD Protections

A floating-base N-type transistor triggered silicon-controlled rectifier (FBNTSCR) device is developed for high-speed I/O electrostatic discharge (ESD) protection. The device, constructed by embedding a floating-base N-type transistor as the trigger element replacing the P-well tie in a standard SCR, enables the embedded bipolar to be avalanched at the collector-emitter breakdown voltage, providing a lower trigger voltage than the conventional LVTSCR. Furthermore, a lower parasitic capacitance is achieved by mitigating the capacitance associated with the N-well/P-well junction. The proposed design also has a shorter inherent SCR path, resulting in lower on-resistance, higher failure current ( $l_{{t}{2}}$ ) and lower overshoot voltage as well as faster turn on speed, all of which benefit the CDM ESD protection performance. Measurement results show the FBNTSCR has ~40.8% reduced trigger voltage, ~68.9% reduced parasitic capacitance and ~16.7% enhanced $l_{{t}{2}}$ compared to the conventional LVTSCR.