Electrostatic Discharge Clamp Device Research Articles

Design of High-Voltage-Tolerant Power-Rail ESD Protection Circuit for Power Pin of Negative Voltage in Low-Voltage CMOS Processes

In the implanted biomedical devices, the silicon chips with monopolar stimulation design have been widely applied. To protect the negative-voltage pins of the implanted silicon chip from the electrostatic discharge (ESD) damage, the ESD protection circuit should be carefully designed to avoid any wrong current path under normal circuit operation with the negative voltage. In this article, a new power-rail ESD clamp circuit for the application with an operating voltage of −6 V has been proposed and verified in a 0.18- $\mu \text{m}$ 3.3-V CMOS process. The proposed circuit, realized with only 3.3-V nMOS/pMOS devices, is able to prevent the gate-oxide reliability issue under this −6-V application. With the proposed ESD detection circuit, the turn-on speed of the main ESD clamp device, which is a stacked-nMOS (STnMOS), can be greatly enhanced. The STnMOS with a width of $400~\mu \text{m}$ can sustain over 8-kV human body model (HBM) ESD stress and perform low standby leakage current of ~5.4 nA at room temperature under the circuit operating condition with −6-V supply voltage.

High Area-Efficient ESD Clamp Circuit With Equivalent $RC$-Based Detection Mechanism in a 65-nm CMOS Process

A power-rail electrostatic discharge (ESD) clamp circuit realized with ESD clamp device drawn in the layout style of big field-effect transistor (BigFET), and with parasitic diode of BigFET as a part of ESD-transient detection mechanism, is proposed and verified in a 65-nm 1.2-V CMOS process. Skillfully utilizing the diode-connected MOS transistor as the equivalent large resistor and the parasitic reverse-biased diodes of BigFET as the equivalent capacitors, the new <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> -based ESD-transient detection mechanism can be achieved without using an actual resistor and capacitor to significantly reduce the layout area by ~82%, as compared to the traditional <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> -based ESD-transient detection circuit. From the measured results, the new proposed power-rail ESD clamp circuit with body effect of ESD clamp device can perform adjustable holding voltage under the ESD stress condition, as well as better immunity against mistrigger and transient-induced latch-on under fast power-on and transient noise conditions.

Two ESD Detection Circuits for 3$\times$ VDD-Tolerant I/O Buffer in Low-Voltage CMOS Processes With Low Leakage Currents

Two novel 3×VDD-tolerant electrostatic discharge (ESD) protection circuits using only low-voltage devices without extra power consumption are proposed for 0.18- μm 1.8-V and 90-nm 1.2-V CMOS processes, respectively. Stacked-capacitor technique and bias circuit are adopted in the two designs. The proposed ESD detection circuits can generate 36- and 38-mA currents to trigger the ESD clamp device under the ESD event. Under normal operating conditions, all the devices are free from the gate-oxide reliability threat. The leakage currents of the 0.18- μm and 90-nm circuits are 0.9 and 200 nA under 3×VDD, respectively. The simulation results show that both the circuits can be successfully used for 3×VDD-tolerant I/O buffers.

Resistor-Less Design of Power-Rail ESD Clamp Circuit in Nanoscale CMOS Technology

A resistor-less power-rail electrostatic discharge (ESD) clamp circuit realized with only thin-gate-oxide devices and with a silicon-controlled rectifier (SCR) as the main ESD clamp device has been proposed and verified in a 65-nm CMOS process. By skillfully utilizing the gate leakage current to realize the equivalent resistor in the ESD-transient detection circuit, the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RC</i> -based ESD detection mechanism can be achieved without using an actual resistor to significantly reduce the layout area in I/O cells. From the measured results, the new proposed power-rail ESD clamp circuit with an SCR width of 45 μm can achieve 5-kV human-body-model and 400-V machine-model ESD levels under the ESD stress event while consuming only a standby leakage current of 1.43 nA at room temperature under the normal circuit operating condition with 1-V bias.

Power-Rail ESD Clamp Circuit With Ultralow Standby Leakage Current and High Area Efficiency in Nanometer CMOS Technology

An ultralow-leakage power-rail electrostatic discharge (ESD) clamp circuit realized with only thin gate oxide devices and with silicon-controlled rectifier (SCR) as the main ESD clamp device has been proposed and verified in a 65-nm CMOS process. By reducing the voltage difference across the gate oxide of the devices in the ESD detection circuit, the proposed power-rail ESD clamp circuit can achieve an ultralow standby leakage current. In addition, the ESD-transient detection circuit can be totally embedded in the SCR device by modifying the layout structure. From the measured results, the proposed power-rail ESD clamp circuit with an SCR width of 45 μm can achieve 7-kV human-body-model and 350-V machine-model ESD levels under the ESD stress event while consuming only a standby leakage current in the order of nanoamperes at room temperature under the normal circuit operating condition with 1-V bias.

New Design of 2 $\times$ VDD-Tolerant Power-Rail ESD Clamp Circuit for Mixed-Voltage I/O Buffers in 65-nm CMOS Technology

A new 2 VDD-tolerant power-rail electrostatic discharge (ESD) clamp circuit realized with only thin gate oxide 1-V (1 VDD) devices and a silicon-controlled rectifier (SCR) as the main ESD clamp device has been proposed and verified in a 65-nm CMOS process. This new design has a low standby leakage current by reducing the voltage difference across the gate oxide of the devices in the ESD detection circuit. The proposed design with an SCR width of 50 can achieve a 6.5-kV human-body-model ESD level, a 300-V machine-model ESD level, and a low standby leakage current of only 103.7 nA at room temperature under the normal circuit operating condition with 1.8 V bias.

New Low-Leakage Power-Rail ESD Clamp Circuit in a 65-nm Low-Voltage CMOS Process

A new low-leakage power-rail electrostatic discharge (ESD) clamp circuit designed with consideration of the gate leakage issue has been proposed and verified in a 65-nm low-voltage CMOS process. Consisting of the new low-leakage ESD-detection circuit and the ESD clamp device of a substrate-triggered silicon-controlled rectifier, the new proposed power-rail ESD clamp circuit realized with only thin-oxide (1-V) devices has a very low leakage current of only 116 nA at room temperature (25°C ) under the power-supply voltage of 1 V. Moreover, the new proposed power-rail ESD clamp circuit can achieve ESD robustness of over 8 kV, 800 V, and over 2 kV in human-body-model, machine-model, and charged-device-model ESD tests, respectively.

High-Voltage-Tolerant ESD Clamp Circuit With Low Standby Leakage in Nanoscale CMOS Process

For system-on-chip applications with mixed-voltage I/O interfaces, I/O circuits with low-voltage devices must drive or receive high-voltage signals to communicate with other circuit blocks. With the consideration of low standby leakage in nanoscale CMOS processes, a new 2 × VDD-tolerant electrostatic discharge (ESD) clamp circuit by using only 1 × VDD devices was presented in this paper. The new ESD clamp circuit had a high-voltage-tolerant ESD detection circuit to improve the turn-on efficiency of an ESD clamp device, which consisted of a silicon-controlled rectifier (SCR) with a diode in series. This design had successfully been verified in a 65-nm CMOS process. The leakage current of this ESD clamp circuit under normal circuit operating condition was only on the order of 100 nA. The test patterns with 25- and 50-m SCR-based ESD clamp devices can achieve 2.6- and 4.8-kV human-body-model ESD robustness, respectively. Such high-voltage-tolerant ESD clamp circuits, by using only low-voltage devices with very low standby leakage current and high ESD robustness, were very suitable for mixed-voltage I/O interfaces in nanoscale CMOS processes.

Design of High-Voltage-Tolerant ESD Protection Circuit in Low-Voltage CMOS Processes

Two new electrostatic discharge (ESD) protection design by using only 1 times VDD low-voltage devices for mixed-voltage I/O buffer with 3 times VDD input tolerance are proposed. Two different special high-voltage-tolerant ESD detection circuits are designed with substrate-triggered technique to improve ESD protection efficiency of ESD clamp device. These two ESD detection circuits with different design concepts both have effective driving capability to trigger the ESD clamp device on. These ESD protection designs have been successfully verified in two different 0.13-mum 1.2-V CMOS processes to provide excellent on-chip ESD protection for 1.2-V/3.3-V mixed-voltage I/O buffers.

ESD Failure Mechanisms of Analog I/O Cells in 0.18-&lt;tex&gt;$muhboxm$&lt;/tex&gt;CMOS Technology

Different electrostatic discharge (ESD) protection schemes have been investigated to find the optimal ESD protection design for an analog input/output (I/O) buffer in 0.18-/spl mu/m 1.8- and 3.3-V CMOS technology. Three power-rail ESD clamp devices were used in power-rail ESD clamp circuits to compare the protection efficiency in analog I/O applications, namely: 1) gate-driven NMOS; 2) substrate-triggered field-oxide device, and 3) substrate-triggered NMOS with dummy gate. From the experimental results, the pure-diode ESD protection devices and the power-rail ESD clamp circuit with gate-driven NMOS are the suitable designs for the analog I/O buffer in the 0.18-/spl mu/m CMOS process. Each ESD failure mechanism was inspected by scanning electron microscopy photograph in all the analog I/O pins. An unexpected failure mechanism was found in the analog I/O pins with pure-diode ESD protection design under ND-mode ESD stress. The parasitic n-p-n bipolar transistor between the ESD clamp device and the guard ring structure was triggered to discharge the ESD current and cause damage under ND-mode ESD stress.

ESD protection design for I/O cells with embedded SCR structure as power-rail ESD clamp device in nanoscale CMOS technology

This paper presents a new electrostatic discharge (ESD) protection design for input/output (I/O) cells with embedded silicon-controlled rectifier (SCR) structure as power-rail ESD clamp device in a 130-nm CMOS process. Two new embedded SCR structures without latchup danger are proposed to be placed between the input (or output) pMOS and nMOS devices of the I/O cells. Furthermore, the turn-on efficiency of embedded SCR can be significantly increased by substrate-triggered technique. Experimental results have verified that the human-body-model (HBM) ESD level of this new proposed I/O cells can be greater than 5 kV in a 130-nm fully salicided CMOS process. By including the efficient power-rail ESD clamp device into each I/O cell, whole-chip ESD protection scheme can be successfully achieved within a small silicon area of the I/O cell.

Electrostatic discharge protection design for mixed-voltage CMOS I/O buffers

A new electrostatic discharge (ESD) protection circuit, using the stacked-nMOS triggered silicon controlled rectifier (SNTSCR) as the ESD clamp device, is designed to protect the mixed-voltage I/O buffers of CMOS ICs. The new proposed ESD protection circuit, which combines the stacked-nMOS structure with the gate-coupling circuit technique into the SCR device, is fully compatible to general CMOS processes without causing the gate-oxide reliability problem. Without using the thick gate oxide, the experimental results in a 0.35 /spl mu/m CMOS process have proven that the human-body-model ESD level of the mixed-voltage I/O buffer can be successfully increased from the original /spl sim/2 kV to >8 kV by using this proposed ESD protection circuit.