静电放电人体模型测试标准EIA/JEDEC中的问题研究

A Case Study of Problems in EIA/JEDEC HBM ESD Test Standard

通过具体的实例说明目前的静电放电(Electrostatic Discharge,ESD)人体模型测试标准EIA/JEDEC尚存在一些需要完善的问题。目前的标准EIA/JEDEC中缺少对起始测试电压的规定,导致有些测试直接从千伏(kV)量级的高压开始进行,造成一些设计不良的ESD防护器件在低压发生失效的状况可能被漏检的后果。本文研究对象为一个漏端带N阱镇流电阻(Nwell-ballast)的GGNMOS(Gate-Grounded NMOS)型ESD防护结构。用Zapmaster对它做人体模型(Human Body Model,HBM)测试,发现从1Kv起测时,能够通过8Kv的高压测试;而从50V起测时,却无法通过350V。TLP测试分析的结果显示此现象确实存在。本文详细剖析了该现象产生的机理,并采用OBIRCH失效分析技术对其进行了佐证。因该问题具有潜在的普遍性,因此提出了对目前业界广泛采用的EIA/JEDEC测试标准进行补充完善的建议。

Discharge There is a current need for modification of EIA/JEDEC Human-Body Model （ HBM ） Electrostatic （ ESD ） test standard, which does not define start and step test voltages. Some measurements start at several kilo-vohs, which ignore that ESD protection devices might fail under low voltage stresses. A Gate-Grounded NMOS （ GGNMOS ） structure with an Nwell-ballast resistor connecting its drain and PAD is investigated for HBM ESD sustaining levels in this paper. When tested with a Zapmaster starting from 1 kilo-volts, the withstand voltage exceeds 8 kilo-volts, whereas the structure failed at 350 volts when the test initiates from 50 volts. The test results from a Transmission-Line Pulsing （ TLP ） system validate the phenomenon. The reason for the failure is also studied and confirmed with OBIRCH Failure Analysis （FA） improving the present EIA/JEDEC HBM ESD test results. To address this general issue, a suggestion for standard for industry applications is made.