Schottky-Embedded Silicon-Controlled Rectifier With High Holding Voltage Realized in a 0.18-μm Low-Voltage CMOS Process

Abstract

The silicon-controlled rectifier (SCR) has been reported to protect CMOS integrated circuits (ICs), due to high ESD robustness within a small silicon area. However, the holding voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</sub> ) of the SCR device was too low to suffer the latch-up issue. Thus, the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</sub> value of the SCR device must be improved to be greater than the circuit operating voltage for safe applications. In this work, the Schottky-embedded modified lateral SCR (SMLSCR) with high holding voltage for ESD protection was proposed and verified in a 0.18-μm 1.8-V/3.3-V CMOS process. By using the Schottky barrier junction, the V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</sub> value of the SCR device can be improved by the reverse-bias Schottky barrier diode (SBD) that is embedded into the SCR device structure. Among those experimental results on the SMLSCR devices with split layout parameters in the silicon test chip, the SMLSCR device without P <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> guard ring has the best second breakdown current ( I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t2</sub> ) of 3.1 A and a high V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h</sub> value of 9.7 V.