Speed optimized diode-triggered SCR (DTSCR) for RF ESD protection of ultra-sensitive IC nodes in advanced technologies

Abstract

A novel diode-triggered silicon-controlled rectifier (DTSCR) (Mergens et al., 2003) electrostatic discharge (ESD) protection element is introduced for low-voltage application (signal and supply voltages /spl les/ 1.8 V) with extremely narrow ESD design margins. Trigger-voltage engineering in conjunction with fast and efficient SCR voltage clamping is applied for the protection of ultrasensitive circuit nodes, such as SiGe heterojunction bipolar transistor (HBT) base regions (e.g., f/sub Tmax/=45 GHz in BiCMOS 0.35-/spl mu/m LNA input) and thin gate oxides (e.g., t/sub ox/=1.7 nm in CMOS 0.09-/spl mu/m high-speed input). Ultrathin gate protection requires a reinforced trigger diode chain to avoid SCR trigger-speed issues resulting in critical trigger-voltage overshoots for very fast ESD transients such as a charged device model (CDM). SCR integration can be realized based on parasitic n-p-n/p-n-p inherent to CMOS devices or can alternatively be implemented based on vertical high-speed SiGe HBT with adjacent p+ SCR anode.