Compact and Fast Response Dual-Directional SCR for Nanoscale ESD Protection Engineering

Abstract

Direct bidirectional current discharge paths between input/output (I/O) and ground (GND) are imperative to achieve robust charged device model (CDM) protection for very stringent design window in advanced low-voltage (LV) processes. In this brief, a compact and fast response dual-directional silicon-controlled rectifier (CFR-DDSCR) has been proposed. Using P-electrostatic discharge (ESD) implantation layer to implement each diode-triggered silicon-controlled rectifier (SCR) within only one n-well, the inherent defect of the prior art (i.e., the cumbersome p-well/n-well triggering diode) is eliminated, ensuring the low resistance of auxiliary triggering path and the compactness of silicon footprint. Moreover, by shielding all internal shallow trench isolation (STIs) with floating high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> metal gates (HKMGs), an all-gate-bounded SCR structure is realized, and all triggering diodes evolve into gated diodes with compact current paths, thus improving the CDM protection capability greatly. Experimental results indicate that the CFR-DDSCR, with a design window suitable for 1.2 V-CMOS technologies, acquires a higher effective CDM robustness (73% improved), a faster turn-on speed (64% improved), and a more compact layout (31% shrunk) compared with its conventional counterpart, which is promising for the advanced LV CDM protection.