内嵌横向PNP晶体管的新型静电放电双向防护器件

Novel dual-direction electrostatic discharge device with lateral PNP transistor

提出一种内嵌横向PNP晶体管的静电放电(ESD)双向防护器件(PNP_DDSCR).对新结构器件在不同ESD应力模式下的响应过程以及电流输运机制进行研究,内嵌横向PNP晶体管的引入,提高了DDSCR系统内部寄生晶体管的注入效率,促进正反馈系统建立,同时引入两条新的电流泄放通路,抑制电导调制效应,提高了电流泄放能力.结果表明,与传统的DDSCR器件相比,PNP_DDSCR器件在传输线脉冲(TLP)测试仿真中触发电压下降了31%,维持电压提高了16.8%,ESD设计窗口优化44.5%,具有更低的导通电阻.快速传输线脉冲(VF-TLP)测试仿真结果表明,新结构器件对瞬态过冲电压有更好的钳位能力,同时保持了较大的开启速度,在VF-TLP应力0.1 A时,PNP_DDSCR器件的过冲电压仅为DDSCR器件的37%.

With the shrinking of semiconductor technology and the increasing of integrated circuits,electrostatic discharge(ESD)as a common natural phenomenon has become one of the main reasons for the failure and reliability reduction of electronic products in integrated circuits.A novel dual-direction ESD device(PNP_DDSCR)with embedded lateral PNP transistor is proposed for diminishing ESD damage.The response process and current transportation of PNP_DDSCR under different ESD stress modes are investigated.Comparative analyses between conventional DDSCR and PNP_DDSCR are executed by TCAD simulation.On the stage of device triggering,the embedded lateral PNP transistor inner DDSCR system provides triggering current for device.The injection efficiency of parasitic transistor in the DDSCR system is improved,and the positive feedback system is promoted.Thus,the holding voltage of PNP_DDSCR is higher than that of conventional DDSCR.At the same time,an extra triggering path introduced by embedded lateral PNP transistor of PNP_DDSCR makes the total triggering path of device shorten.Therefore,the transient overshoot voltage of PNP_DDSCR is lower than that of DDSCR.For thermal performance,most of the heat first accumulates near the lateral PNP transistor,and then the peak point of heat turns to main SCR path with the conduction of PNP_DDSCR.The heat accumulation in PNP_DDSCR is shared by the path of embedded lateral PNP transistor.As a result,the average temperature in PNP_DDSCR is lower than that in DDSCR and the ability of PNP_DDSCR to dissipate heat is more perfect.Comparing with DDSCR,the conclusions are obtained.Under the condition of transmission line pulse(TLP)test simulation analyses,the triggering voltage is reduced by 31%,the holding voltage is increased by 16.8%,the ESD design window is optimized by 44.5%,and on-resistance is lower.When TLP stress is 2.67 A,the average temperature of PNP_DDSCR is much lower than that of traditional DDSCR in the whole conduction process.With the increase of pulse lasting time,average temperature difference between two devices becomes great further.According to the very fast TLP(VF-TLP)testing results,clamping capability of PNP_DDSCR under transient overshoot voltage is more stable under the condition of fast turn-on speed.When the VF-TLP stress is 0.1 A,the overshoot voltage of PNP_DDSCR device is the 37%of that of DDSCR device while the PNP_DDSCR maintains a relatively fast triggering speed.Thus,the ESD protection capability of PNP_DDSCR is superior.