亚微米CMOS工艺中GG-NMOS结构ESD保护电路改进设计

针对采用GG-NMOS结构ESD保护电路的IC芯片在实际应用中出现ESD失效现象,在不额外增加版图面积的情况下通过引入栅耦合技术对现有的ESD保护结构进行改进,并达到了预期效果.实验结果显示其性能达到了人体放电模式的2级标准(HBM:3000V),机器模式3级标准(MM:400V).     

一种CMOS IC片上电源ESD保护电路

随着集成电路工艺的高速发展,特征尺寸越来越小,静电放电对CMOS器件可靠性的危害也日益增大,ESD保护电路设计已经成为IC设计中的一个重要部分.讨论了两种常见的CMOS集成电路电源系统ESD保护电路,分析了它们的电路结构、工作原理和存在的问题,进而提出了一种改进的电源动态侦测ESD保护电路.使用HSPICE仿真验证了该电路工作的正确性,并且在一款自主芯片中使用,ESD测试通过士3000 V.     

一种多电源域专用数字电路的静电失效分析及提升研究

在静电放电(ESD)能力考核时,一种多电源域专用数字电路在人体模型(HBM)1 700 V时失效。通过HBM测试、激光束电阻异常侦测(OBIRCH)失效分析方法,定位出静电试验后失效位置。根据失效分析结果并结合理论分析,失效是静电二极管的反向静电能力弱所致。利用晶体管替换静电二极管,并对OUT2端口的内部进行静电版图优化设计。改版后,该电路的ESD防护能力达2 500 V以上。该项研究结果对于多电源域专用数字电路的ESD失效分析及能力提升具有参考价值。     

由版图引起的CMOS ESD保护电路失效的分析

ESD保护电路已经成为CMOS集成电路不可或缺的组成部分,在当前CMOS IC特征尺寸进入深亚微米时代后,如何避免由ESD应力导致的保护电路的击穿已经成为CMOS IC设计过程中一个棘手的问题.光发射显微镜利用了IC芯片失效点所产生的显微红外发光现象可以对失效部位进行定位,结合版图分析以及微分析技术,如扫描电子显微镜SEM、聚焦离子束FIB等的应用可以揭示ESD保护电路的失效原因及其机理.通过对两个击穿失效的CMOS功率ICESD保护电路实际案例的分析和研究,提出了改进ESD保护电路版图设计的途径.     

双界面智能卡芯片模拟前端ESD设计

双界面智能卡芯片静电放电(ESD)可靠性的关键是模拟前端(AFE)模块的ESD可靠性设计,如果按照代工厂发布的ESD设计规则设计,AFE模块的版图面积将非常大.针对双界面智能卡芯片AFE电路结构特点和失效机理,设计了一系列ESD测试结构.通过对这些结构的流片和测试分析,研究了器件设计参数和电路设计结构对双界面智能卡芯片ESD性能的影响.定制了适用于双界面智能卡芯片AFE模块设计的ESD设计规则,实现对ESD器件和AFE内核电路敏感结构的面积优化,最终成功缩小了AFE版图面积,降低了芯片加工成本,并且芯片通过了8 000 V人体模型(HBM) ESD测试.     

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。     

基于SiGe BiCMOS工艺的射频ESD电路设计

随着射频电路工作频率的不断升高,ESD已经成为了影响电路可靠性和射频电路性能的重要因素。针对高速射频电路,设计了高速I/O口ESD防护电路和电源到地的箝位电路,并采用斜边叉指型二极管进行版图和性能优化。采用Jazz 0.18μm SiGe BiCMOS工艺对该ESD防护电路进行设计和流片。经过测试得到,ESD保护电压最高可达到3000 V。更改二极管叉指数取得更高的ESD防护级别,改进后保护电压最高可达到4500 V。     

数模混合电路的全芯片防静电保护

随着集成电路的迅速发展,特别是数模混合电路的广泛应用,静电放电(ESD)已成为导致集成电路内部静电损伤的可靠性问题,它常常在集成电路的输入、输出端口以及从电源到地的电路内部形成,给芯片的制造和设计带来了很大的困难.文章对芯片防静电保护电路进行了总结,分析和讨论了几种数模混合电路防静电保护技术.     

E~2PROM工艺的ESD保护电路失效分析

ESD保护电路已经成为集成电路不可或缺的组成部分,如何避免由ESD应力导致的保护电路的击穿已经成为CMOSIC设计过程中一个棘手的问题。光发射显微镜利用了IC芯片失效点所产生的显微红外发光现象可以对失效部位进行定位,结合版图分析以及微分析技术,如扫描电子显微镜SEM、微红外发光显示设备EMMI等的应用可以揭示ESD保护电路的失效原因及机理。文章通过对一组击穿失效的E2PROM工艺的ESD保护电路实际案例的分析和研究,介绍了几种分析工具,并且在ESD失效机制的基础上,提出了改进ESD保护电路的设计途径。     

CMOS VLSI ESD保护电路设计技术

本文对CMOSVLSI芯片ESD失效现象及其ESD事件发生机理进行了分析,介绍了CMOSVLSIESD保护电路设计技术。使用具有大电流放电性能的MOS器件构成的ESD电路,以及采用周密的版图布局布线技术,可实现良好的ESD保护性能。     

Investigation on device characteristics of MOSFET transistor placed under bond pad for high-pin-count SOC applications

In the system-on-a-chip (SOC) era, chip layouts of integrated circuit (IC) products become more and more compact for cost reduction. To save layout area for SOC chips, on-chip electrostatic discharge (ESD) protection devices or input/output (I/O) transistors placed under bond pads is a good choice. To ensure that this choice is practicable, a test chip with large size NMOS devices placed under bond pads had been fabricated in a 0.35-/spl mu/m 1P4M 3.3-V CMOS process for verification. The bond pads of this test chip had been drawn with different layout patterns on the interlayer metals for two purposes. One is to investigate the efficiency against bonding stress applied on the active devices under the bond pads. The other purpose is to reduce the parasitic capacitance of bond pads for high-speed or high-frequency circuit applications. DC characteristics of these devices placed under bond pads had been measured under three conditions: before wire bonding, after wire bonding, and after thermal reliability stresses. After assembly with wire bond package and thermal reliability stresses, the measured results show that there are only little variations between devices under bond pads and devices beside bond pads. This result can be applied to save layout area of IC products by realizing on-chip ESD protection devices or I/O transistors under the bond pads, especially for the high-pin-count SOC.     

Design optimization of ESD protection and latchup prevention for a serial I/O IC

ESD/latchup are often two contradicting variables during IC reliability development. Trade-off between the two must be properly adjusted to realize ESD/latchup robustness of IC products. A case study on SERIAL Input/Output (I/O) IC’s is reported here to reveal this ESD/latchup optimization issue. SERIAL I/O IC features a special clamping property to wake up PC’s during system standby situation. Along with high voltage operation, Input/Output (I/O) protection design of this IC becomes one of the most challenging tasks in the product reliability development. In the initial development phase, ignorance of latchup susceptibility resulted in severe Electrical Overstress (EOS) damage during latchup tests, and also gave a false over estimate of ESD protection threshold through parasitic latchup paths. The latchup origin is an output PMOS and floating-well ESD triggering NMOS beside the PMOS, and the main fatal link is this high-voltage (HV) NMOS connecting to a bi-directional SCR cell. This fatal link led to totally five latchup sites and three latchup paths clarified through careful and intensive FIB failure analysis, while this powerful SCR ESD device without appropriate triggering mechanism still could not provide sufficient product-level ESD hardness. Owing to there being no design window between ESD and latchup, the original several protection schemes were all abandoned. Using this bi-directional SCR ESD cell and proper triggering PNP bipolar transistors, a new I/O protection circuit could sustain at least ESD/HBM 4 kV and latchup triggering current 150 mA tests, thus accomplish the best optimization of ESD/latchup robustness.     

集成电路中接口电路的可靠性设计

在集成电路设计中,可将承担静电放电保护、电平转换、电路驱动等功能的电路组合成接口电路,通过对接口电路的可靠性设计来提高集成电路的可靠性。从电路设计、版图设计、封装设计等设计阶段的特点出发,阐述了各阶段可靠性设计的内容,并总结了一些设计要点和设计准则,提出了可采用接口电路、封装、PCB三者协同设计的方法,以提高接口电路的可靠性。     

ESD Protection Design With On-Chip ESD Bus and High-Voltage-Tolerant ESD Clamp Circuit for Mixed-Voltage I/O Buffers

Considering gate-oxide reliability, a new electrostatic discharge (ESD) protection scheme with an on-chip ESD bus (ESD_BUS) and a high-voltage-tolerant ESD clamp circuit for 1.2/2.5 V mixed-voltage I/O interfaces is proposed. The devices used in the high-voltage-tolerant ESD clamp circuit are all 1.2 V low-voltage N- and P-type MOS devices that can be safely operated under the 2.5-V bias conditions without suffering from the gate-oxide reliability issue. The four-mode (positive-to-V_SS, negative-to-V_SS, positive-to-V_DD, and negative-to-V_DD) ESD stresses on the mixed-voltage I/O pad and pin-to-pin ESD stresses can be effectively discharged by the proposed ESD protection scheme. The experimental results verified in a 0.13-mum CMOS process have confirmed that the proposed new ESD protection scheme has high human-body model (HBM) and machine-model (MM) ESD robustness with a fast turn-on speed. The proposed new ESD protection scheme, which is designed with only low- voltage devices, is an excellent and cost-efficient solution to protect mixed-voltage I/O interfaces.     

Internal chip ESD phenomena beyond the protection circuit

Input/output electrostatic discharge (ESD) circuit requirements call for good protection of the pin with respect to both the ground and the power bus pins. Although effective protection can be designed at the pin many cases of damage phenomena are known to occur internal to the chip beyond the protection circuit. Here, the issues of protection between V_DD and V_SS are discussed first. This is followed by examples of how protection circuit performance can be sensitive to internal chip layout, independent of its effective design. Several illustrative actual case studies are reported to emphasize the internal chip ESD phenomena and their adverse effects     

Improving ESD protection of 5 V NMOSFET large array device in 0.4 μm BCD process

In the output stage of power ICs, large array devices (LAD) of MOSFETs are usually used to drive a considerable amount of current. Electrostatic discharge (ESD) self-protection capability of LAD is also required. ESD layout rules are usually adopted in low voltage CMOS transistors to improve the ESD performance but with a large layout area. In this paper, a modified RC gate-driven circuit with gate signal control circuit is developed to keep the minimum device layout rule while achieving ESD self-protection. Thus, it results in a very small layout area increment while keeps the LAD operates safely in normal operation and gains good ESD protection level.     

基于STNMOS的混合电压I／O接口ESD保护

混合电压I／O接口的静电放电（electrostaticdischarge,ESD）保护设计是小线宽工艺中片上系统（SoC）设计的主要挑战之一。混合电压I／O接口的片上ESD保护既要避免栅氧可靠性问题,又要防止不期望的泄漏电流路径产生。这篇论文讨论了基于堆叠NMOS（Stacked—NMOS,STNMOS）的混合电压I／O接口的ESD保护设计构思和电路实现,通过不同ESD保护设计方案的比较,提出了一个最有效的保护方案。     

ESD protection design on analog pin with very low input capacitancefor high-frequency or current-mode applications

An electrostatic discharge (ESD) protection design is proposed to solve the ESD protection challenge to the analog pins: for high-frequency or current-mode applications, By including an efficient power-rails clamp circuit in the analog input/output (I/O) pin, the device dimension (W/L) of an ESD clamp device connected to the I/O pad in the analog ESD protection circuit can be reduced to only 50/0.5 (μm/μm) in a 0.35-μm silicided CMOS process, but it can sustain the human body model (HBM) and machine model (MM) ESD level of up to 6 kV (400 V). With such a smaller device dimension, the input capacitance of this analog ESD protection circuit can be significantly reduced to only ~1.0 pF (including the bond-pad capacitance) for high-frequency applications