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.     

Self-triggered stacked silicon-controlled rectifier structure (STSSCR) for on-chip electrostatic discharge (ESD) protection

In order to improve the holding voltage and keep the trigger voltage of the silicon controlled rectifier (SCR) devices, a new self-triggered stacked SCR structure (STSSCR) is proposed for on–chip electrostatic discharge (ESD) protection. The STSSCR structure consists of a modified lateral SCR (MLSCR) and multiple double trigger SCRs (DTSCRs). The trigger voltage of the structure is decided by the trigger voltage of the MLSCR. And the holding voltage is decided by the holding voltage of the SCRs and the number of the DTSCR in the STSSCR structure. The simulation and experimental results show that STSSCR has a stable trigger voltage, a small trigger current and an adjustable high holding voltage.     

Electrostatic discharge (ESD) protection for CMOS output buffers in scaled-down VLSI technology

To provide area-efficient output ESD protection for the scaled-down CMOS VLSI, a new output ESD protection is proposed. In the new output ESD protection circuit, there are two novel devices, the PTLSCR (PMOS-trigger lateral SCR) and the NTLSCR (NMOS-trigger lateral SCR). The PTLSCR is in parallel and merged with the output PMOS, and the NTLSCR is in parallel and merged with the output NMOS, to provide area-efficient ESD protection for CMOS output buffers. The trigger voltages of PTLSCR and NTLSCR are lowered below the breakdown voltages of the output PMOS and NMOS in the CMOS output buffer. The PTLSCR and NTLSCR are guaranteed to be turned on first before the output PMOS or NMOS are broken down by the ESD voltage. Experimental results have shown that the PTLSCR and NTLSCR can sustain over 4000 V (700 V) of the human-body-model (machine-model) ESD stresses within a very small layout area in a 0.6 μm CMOS technology with LDD and polycide processes. The noise margin of the proposed output ESD protection design is greater than 8 V (lower than −3.3 V) to avoid the undesired triggering on the NTLSCR (PTLSCR) due to the overshooting (undershooting) voltage pulse on the output pad when the IC is under normal operating conditions with 5 V VDD and 0 V VSS power supplies.     

A new multi-finger SCR-based structure for efficient on-chip ESD protection

This paper introduces a new SCR-based (silicon controlled rectifier) structure for on-chip ESD protection. The STMSCR (smart triggered multi-finger SCR) relies on the bimodal operation of a LSCR (lateral SCR) using an external triggering circuitry that permits switching from a transparency mode to a protection mode as soon as an ESD event is detected. The trigger voltage can be adjusted by design without any impact on the ESD performance. The STMSCR is multi-finger compliant, thus allowing area-efficient design of pad-located ESD protection. The STMSCR is demonstrated in a 0.18 μm CMOS technology without any process customization; an HBM failure threshold over 115 V/μm is reached while always ensuring current uniformity in multi-finger structures.     

A gate-coupled PTLSCR/NTLSCR ESD protection circuit fordeep-submicron low-voltage CMOS ICs

A novel electrostatic discharge (ESD) protection circuit, which combines complementary low-voltage-triggered lateral SCR (LVTSCR) devices and the gate-coupling technique, is proposed to effectively protect the thinner gate oxide of deep submicron CMOS ICs without adding an extra ESD-implant mask. Gate-coupling technique is used to couple the ESD-transient voltage to the gates of the PMOS-triggered/NMOS-triggered lateral silicon controlled rectifier (SCR) (PTLSCR/NTLSCR) devices to turn on the lateral SCR devices during an ESD stress. The trigger voltage of gate-coupled lateral SCR devices can be significantly reduced by the coupling capacitor. Thus, the thinner gate oxide of the input buffers in deep-submicron low-voltage CMOS ICs can be fully protected against ESD damage. Experimental results have verified that this proposed ESD protection circuit with a trigger voltage about 7 V can provide 4.8 (3.3) times human-body-model (HBM) [machine-model (MM)] ESD failure levels while occupying 47% of layout area, as compared with a conventional CMOS ESD protection circuit     

一个LVTSCR并联PMOS的高维持电压ESD防护器件

为了在5 V片上输入输出端进行静电放电(ESD)防护,提出了一种新型的LVTSCR结构。使用Silvaco 2D TCAD软件对此器件进行包含电学及热学特性的仿真。此新型器件交换了LVTSCR中N-Well的N+、P+掺杂区并引入了一个类PMOS结构用来在LVTSCR工作前释放ESD电流。器件仿真结果显示,与LVTSCR相比,该器件获得了更高的维持电压(10.51 V),以及更高的开启速度(1.05×10-10 s),同时触发电压仅仅从12.45 V增加到15.35 V。并且,如果加入的PMOS结构选择与NMOS相同的沟道长度,器件不会引起热失效问题。     

基于UTB-SOI技术的双辅助触发SCR ESD防护器件研究

为了提高FDSOI ESD防护器件的二次击穿电流,基于UTB-SOI技术,提出了一种SOI gg-NMOS和寄生体硅PNP晶体管双辅助触发SCR器件。通过gg-NMOS源区的电子注入和寄生PNP晶体管的开启,共同辅助触发主泄放路径SCR,快速泄放ESD电流。TCAD仿真结果表明,新结构能够泄放较高的二次击穿电流,具有可调节的触发电压。     

Optimization on MOS-Triggered SCR Structures for On-Chip ESD Protection

MOS-triggered silicon-controlled rectifier (SCR) devices have been reported to achieve efficient on-chip electrostatic discharge (ESD) protection in deep-submicrometer CMOS technology. The channel length of the embedded MOS transistor in the MOS-triggered SCR device dominates the trigger mechanism and current distribution to govern the trigger voltage, holding voltage, on resistance, second breakdown current, and ESD robustness of the MOS-triggered SCR device. The embedded MOS transistor in the MOS-triggered SCR device should be optimized to achieve the most efficient ESD protection in advanced CMOS technology. In addition, the layout style of the embedded MOS transistor can be adjusted to improve the MOS-triggered SCR device for ESD protection.     

0.18μm RF CMOS双向可控硅ESD防护器件的研究(英文)

基于传统双向可控硅(DDSCR)提出了两种静电放电(ESD)保护器件,可应对正、负ESD应力从而在2个方向上对电路进行保护。传统的DDSCR通过N-well与P-well之间的雪崩击穿来触发,而提出的新器件则通过嵌入的NMOS/PMOS来改变触发机制、降低触发电压。两种改进结构均在0.18μmRFCMOS下进行流片,并使用传输线脉冲测试系统进行测试。实验数据表明,这两种新器件具有低触发电压、低漏电流(～nA),抗ESD能力均超过人体模型2kV,同时具有较高的维持电压(均超过3.3V),可保证其可靠地用于1.8V、3.3V I/O端口而避免出现闩锁问题。     

Implementation of Initial-On ESD Protection Concept With PMOS-Triggered SCR Devices in Deep-Submicron CMOS Technology

In order to enhance the applications of SCR devices for deep-submicron CMOS technology, a novel SCR design with "initial-on" function is proposed to achieve the lowest trigger voltage and the highest turn-on efficiency of SCR device for effective on-chip ESD protection. Without using the special native device (NMOS with almost zero or even negative threshold voltage) or any process modification, this initial-on SCR design is implemented by PMOS-triggered SCR device, which can be realized in general CMOS processes. This initial-on SCR design has a high enough holding voltage to avoid latchup issues in a VDD operation voltage of 2.5 V. The new proposed initial-on ESD protection design with PMOS-triggered SCR device has been successfully verified in a fully-silicided 0.25-mum CMOS process     

应用于片上ESD防护中新式直通型MOS触发SCR器件的研究

在基于0.13μm CMOS工艺制程下,为研究片上集成电路ESD保护,对新式直通型MOS触发SCR器件和传统非直通型MOS触发SCR进行了流片验证,并对该结构各类特性进行了具体研究分析。实验采用TLP(传输线脉冲)对两类器件进行测试验证,发现新式直通型MOS触发SCR结构要比传统非直通型MOS触发SCR具有更低的触发电压、更小的导通电阻、更好的开启效率以及更高的失效电流。     

Temperature-dependent dynamic triggering characteristics of SCR-type ESD protection circuits

Experimental analysis of the dynamic characteristics of various silicon-controlled rectifier (SCR)-type ESD protection circuits at various temperatures has been carried out. These circuits include MOSFET-trigger SCR (MTSCR), diode-chain-trigger SCR (DCTSCR), low-voltage zener diode trigger SCR (ZDSCR), low-voltage trigger SCR (LVTSCR) and gate-coupled low-voltage trigger SCR (GCSCR) circuits. The static trigger voltage increases with temperature if the SCR uses the breakdown trigger mechanism, otherwise it decreases with temperature. The peak pad voltages for the MTSCR and DCTSCR subjected to a pulse-like ESD stress decrease with increasing temperature, while those of GCSCR and LVTSCR are relatively insensitive to temperature.     

一种基于CMOS工艺的新型结构ESD保护电路

根据伞芯片静电放电(ESD)损伤防护理论,设计了一种新犁结构保护电路,采用0.6μm标准CMOS p阱工艺进行了新型保护电路的多项目晶圆(MPW)投片验证.通过对同一MPW中的新型结构ESD保护电路和具有同样宽长比的传统栅极接地MOS(GG-nMOS)保护电路的传输线脉冲测试,结果表明在不增加额外工艺步骤的前提下,本文设计的新型结构ESD保护电路芯片面积减少了约22%,静态电流更低,而抗ESD电压提高了近32%.该保护电路通过了5kV的人体模型测试.     

一种新型的高维持电压可控硅

可控硅(SCR)作为静电放电(ESD)保护器件,因具有高的鲁棒性而被广泛应用,但其维持电压很低,容易导致闩锁问题。针对高压集成电路的ESD保护,提出了一种新颖的具有高维持电压的SCR结构(HHVSCR)。通过添加一个重掺杂的N型掺杂层(NIL),减小了SCR器件自身固有的正反馈效应,从而提高了SCR的维持电压。Sentaurus TCAD仿真结果表明,与传统的SCR相比,改进的HHVSCR无需增加额外的面积就可将维持电压从1.88 V提高到11.9 V,可应用于高压集成电路的ESD防护。     

A novel SCR ESD protection for triple well CMOS technologies

A novel SCR structure for on-chip ESD protection implemented with a deep submicron triple well CMOS technology is presented. The triple well technology offers the possibility of biasing the p-well, on which the structure is built, under transient ESD stress conditions and independently from the substrate. This greatly affects the turn on mechanism of the structure. Unlike conventional SCR devices, the proposed p-well coupled SCR offers a reduced triggering voltage level as well as the enhanced ESD performance of the SCR devices. The turn on of this structure is realized with a common RC trigger network. The concept is supported by device simulation results     

Design of SCR‐Based ESD Protection Circuit for 3.3 V I/O and 20 V Power Clamp

In this paper, MOS‐triggered silicon‐controlled rectifier (SCR)–based electrostatic discharge (ESD) protection circuits for mobile application in 3.3 V I/O and SCR‐based ESD protection circuits with floating diffusion regions for inverter and light‐emitting diode driver applications in 20 V power clamps were designed. The breakdown voltage is induced by a grounded‐gate NMOS (ggNMOS) in the MOS‐triggered SCR‐based ESD protection circuit for 3.3 V I/O. This lowers the breakdown voltage of the SCR by providing a trigger current to the P‐well of the SCR. However, the operation resistance is increased compared to SCR, because additional diffusion regions increase the overall resistance of the protection circuit. To overcome this problem, the number of ggNMOS fingers was increased. The ESD protection circuit for the power clamp application at 20 V had a breakdown voltage of 23 V; the product of a high holding voltage by the floating diffusion region. The trigger voltage was improved by the partial insertion of a P‐body to narrow the gap between the trigger and holding voltages. The ESD protection circuits for low‐ and high‐voltage applications were designed using 0.18 µm Bipolar‐CMOS‐DMOS technology, with 100 µm width. Electrical characteristics and robustness are analyzed by a transmission line pulse measurement and an ESD pulse generator (ESS‐6008).     

Lateral SCR devices with low-voltage high-current triggeringcharacteristics for output ESD protection in submicron CMOS technology

A high-current PMOS-trigger lateral SCR (HIPTSCR) device and a high-current NMOS-trigger lateral SCR (HINTSCR) device with a lower trigger voltage but a higher trigger current are proposed to improve ESD robustness of CMOS output buffer in submicron CMOS technology. The lower trigger voltage is achieved by inserting short-channel thin-oxide PMOS or NMOS devices into the lateral SCR structures. The higher trigger current is achieved by inserting the bypass diodes into the structures of the HIPTSCR and HINTSCR devices. These HIPTSCR and HINTSCR devices have a lower trigger voltage to effectively protect the output transistors in the ESD-stress conditions, but they also have a higher trigger current to avoid the unexpected triggering due to the electrical noise on the output pad when the CMOS ICs are in the normal operating conditions. Experimental results have verified that the trigger current of the proposed HIPTSCR (HINTSCR) is increased up to 225.5 mA (218.5 mA). But, the trigger voltage of the HIPTSCR (HINTSCR) remains at a lower value of 13.4 V (11.6 V). The noise margin against the overshooting (undershooting) voltage pulse on the output pad, without accidentally triggering on the HINTSCR (HIPTSCR), can be greater than VDD+12 V (VSS -12 V). These HIPTSCR and HINTSCR devices have been practically used to protect CMOS output buffers with a 4000-V (700-V) HEM (MM) ESD robustness but only within a small layout area of 37.6×60 μm² in a standard 0.6-μm CMOS technology without extra process modification     

Substrate-triggered ESD protection circuit without extra process modification

A substrate-triggered technique is proposed to improve electrostatic discharge (ESD) protection efficiency of ESD protection circuits without extra salicide blocking and ESD-implantation process modifications in a salicided shallow-trench-isolation CMOS process. By using the layout technique, the whole ESD protection circuit can be merged into a compact device structure to enhance the substrate-triggered efficiency. This substrate-triggered design can increase ESD robustness and reduce the trigger voltage of the ESD protection device. This substrate-triggered ESD protection circuit with a field oxide device of channel width of 150 /spl mu/m can sustain a human-body-model ESD level of 3250 V without any extra process modification. Comparing to the traditional ESD protection design of gate-grounded nMOS (ggnMOS) with silicide-blocking process modification in a 0.25-/spl mu/m salicided CMOS process, the proposed substrate-triggered design without extra process modification can improve ESD robustness per unit silicon area from the original 1.2 V//spl mu/m/sup 2/ of ggnMOS to 1.73 V//spl mu/m/sup 2/.     

Latchup-free ESD protection design with complementary substrate-triggered SCR devices

The turn-on mechanism of silicon-controlled rectifier (SCR) devices is essentially a current triggering event. While a current is applied to the base or substrate of an SCR device, it can be quickly triggered on into its latching state. In this paper, latchup-free electrostatic discharge (ESD) protection circuits, which are combined with the substrate-triggered technique and an SCR device, are proposed. A complementary circuit style with the substrate-triggered SCR device is designed to discharge both the pad-to-V/sub SS/ and pad-to-V/sub DD/ ESD stresses. The novel complementary substrate-triggered SCR devices have the advantages of controllable switching voltage, adjustable holding voltage, faster turn-on speed, and compatible to general CMOS process without extra process modification such as the silicide-blocking mask and ESD implantation. The total holding voltage of the substrate-triggered SCR device can be linearly increased by adding the stacked diode string to avoid the transient-induced latchup issue in the ESD protection circuits. The on-chip ESD protection circuits designed with the proposed complementary substrate-triggered SCR devices and stacked diode string for the input/output pad and power pad have been successfully verified in a 0.25-/spl mu/m salicided CMOS process with the human body model (machine model) ESD level of /spl sim/7.25 kV (500 V) in a small layout area.     

2.4GHz低噪声放大器的全芯片ESD保护设计

设计并流片验证了一种0.18μmRFCMOS工艺的2.4GHz低噪声放大器的全芯片静电放电(ESD)保护方案。对于射频(RF)I/O口的ESD防护,主要对比了二极管、可控硅(SCR)以及不同版图的互补型SCR,经流片与测试,发现岛屿状互补型SCR对I/O端口具有很好的ESD防护综合性能。对于电源口的ESD防护,主要研究了不同触发方式的ESD保护结构,结果表明,RCMOS触发SCR结构(RCMOS-SCR)具有良好的ESD鲁棒性和开启速度。基于上述结构的全芯片ESD保护设计,RF I/O口采用岛屿状布局的互补SCR结构的ESD防护设计,该ESD防护电路引入0.16dB的噪声系数和176fF的寄生电容,在人体模型(HBM)下防护能力可达6kV;电源口采用了RCMOS-SCR,实现了5kV HBM的ESD保护能力,该设计方案已经在有关企业得到应用。