保护环版图结构对ESD防护器件耐压能力的影响

基于华润上华0.5 μm双极-CMOS-DMOS (BCD)工艺设计制备了不同保护环分布情况下的叉指型内嵌可控硅整流器的横向扩散金属氧化物半导体(LDMOS-SCR)结构器件,并利用传输线脉冲(TLP)测试比较静电放电(ESD)防护器件的耐压能力.以LDMOS-SCR结构为基础,按照16指、8指、4指和2指设置保护环,形成4种不同类型的版图结构.通过器件的直流仿真分析多指器件的开启情况,利用传输线脉冲测试对比不同保护环版图结构的耐压能力.仿真和测试结果表明,改进后的3类版图结构相对于普遍通用的第一类版图结构,二次击穿电流都有所提升,其中每8指设置一个保护环的版图结构二次击穿电流提升了76.36％,其单位面积的鲁棒性能也最好,为相应工艺设计最高耐压值的ESD防护器件提供了参考结构和方法.

Impact of Guard Ring Layout Structure on the Voltage-Tolerance Capacity of ESD Protection Devices

A embedded multi-finger laterally diffused metal oxide semiconductor silicon-controlled rectifier (LDMOS-SCR) structural devices with different types of guard ring layout were designed and fabricated in a CSMC 0.5 μm bipolar-CMOS-DMOS (BCD) process.And the transmission line pulse (TLP) testing was used to compare the vohage-tolerance capacity of these electrostatic discharge (ESD) protection devices.Based on the LDMOS-SCR structure,16,8,4 and 2 fingers were surrounded by guard rings,then four different guard ring layout structures were grouped.The turn-on condition of the multi-finger devices was analyzed by the direct-current simulation device,and the voltage-tolerance capacity of different guard ring layout structures were compared with the TLP testing.Simulation and test results show that the secondary breakdown current of three optimized types of layout structures are higher than that of the conventional one.The type whose eight fingers are surrounded by one guard ring provides 76.36％ inprovement of the secondary breakdown current,and has the strongest robustness per unit area.These devices can provide a reference structure and method for the design of highest voltage-tolerance ESD protection devices in the corresponding process.