三维数值仿真研究锗硅异质结双极晶体管总剂量效应

为探索锗硅异质结双极晶体管(SiGe HBT)总剂量效应的损伤机理,采用半导体器件三维模拟工具(TCAD),建立电离辐照总剂量效应损伤模型,分析比较电离辐射在SiGe HBT不同氧化层结构的不同位置引入陷阱电荷缺陷后,器件正向Gummel特性和反向Gummel特性的退化特征,获得SiGe HBT总剂量效应损伤规律,并与⁶⁰Coγ辐照实验进行对比.结果表明:总剂量辐照在SiGe HBT器件中引入的氧化物陷阱正电荷主要在pn结附近的Si/SiO₂界面处产生影响,引起pn结耗尽区的变化,带来载流子复合增加,最终导致基极电流增大、增益下降;其中EB Spacer氧化层中产生的陷阱电荷主要影响正向Gummel特性,而LOCOS隔离氧化层中的陷阱电荷则是造成反向Gummel特性退化的主要因素.通过数值模拟分析获得的SiGe HBT总剂量效应损伤规律与不同偏置下⁶⁰Coγ辐照实验的结论符合得较好.

Three-dimensional simulation of total ionizing dose effect on SiGe heterojunction bipolor transistor

The damage mechanism of the total ionizing dose(TID)effect of SiGe heterojunction bipolor transistar(SiGe HBT)is explored by using three-dimensional simulation of semiconductor device(TCAD).In the simulation,the trapped charge defects are introduced into different locations of oxidationin SiGe HBT to simulate the TID effect.Then the degradation characteristics of the forward Gummel characteristic and the reverse Gummel characteristic of the device are analyzed,and the TID damage law of SiGe HBT is obtained.Finally,the simulation results are compared with the⁶⁰Coγirradiation test results,showing that the trapped charges introduced by TID irradiation in SiGe HBT device mainly affect the Si/SiO₂interface near the p-n junction,resulting in the change in the depletion region of the p-n junction and the increase of carrier recombination.Eventually,the base current increases and the gain decreases.The trapped charges generated in the EB spacer oxide layer mainly affect the forward Gummel characteristics,and the trapped charges in the LOCOS isolation oxide layer are the main factor causing the reverse Gummel characteristics to degrade.The experimental results on⁶⁰Coγirradiation under different biases are consistent with those from the total dose effect damage law of SiGe HBT obtained by numerical simulation analysis.