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.     

硅单粒子位移损伤多尺度模拟研究

本文结合分子动力学方法和动力学蒙特卡罗方法, 研究了单个粒子入射硅引起的位移损伤缺陷的产生和演化过程; 基于Shockley-Read-Hall理论计算了单个粒子入射引起的位移损伤缺陷导致的泄漏电流增加及其演化过程, 比较了缺陷退火因子与泄漏电流退火因子之间的差异, 并将计算结果与实验值进行了对比. 结果表明, 计算泄漏电流时, 仅考虑一种缺陷的情况下缺陷退火因子与泄漏电流退火因子相同, 考虑两种缺陷类型情况下二者在数值上有所区别, 但缺陷退火因子仍能在一定程度上反映泄漏电流的退火行为. 分子动力学模拟中采用Stillinger-Weber势函数和Tersoff势函数时缺陷退火因子和泄漏电流退火因子与实验结果一致, 基于Stillinger-Weber势函数的计算结果与实验值更为接近.     

锗硅异质结双极晶体管单粒子效应加固设计与仿真

本文设计了一种通过在版图布局中引入伪集电极的方法来提高锗硅异质结双极晶体管(SiGe HBT)抗单粒子性能的方法. 利用半导体器件模拟工具, 针对加固前后的SiGe HBT开展了单粒子效应仿真模拟, 分析了伪集电极对SiGe HBT电荷收集机理的影响. 结果表明, 引入的伪集电极形成的新的集电极-衬底结具有较大的反偏能力, 加固后SiGe HBT伪集电极通过扩散机理, 大量收集单粒子效应产生的电荷, 有效地减少了实际集电极的电荷收集量, 发射极、基极电荷收集量也有不同程度的降低, 加固设计后SiGe HBT 的单粒子效应敏感区域缩小, 有效的提高了SiGe HBT 器件抗单粒子效应辐射性能. 此项工作的开展为SiGe HBT电路级单粒子效应抗辐射加固设计打下良好的基础.     

An investigation of ionizing radiation damage in different SiGe processes

Different SiGe processes and device designs are the critical influences of ionizing radiation damage. Based on the different ionizing radiation damage in SiGe HBTs fabricated by Huajie and an IBM SiGe process, quantitatively numerical simulation of ionizing radiation damage was carried out to explicate the distribution of radiation-induced charges buildup in KT9041 and IBM SiGe HBTs. The sensitive areas of the EB-spacer and isolation oxide of KT9041 are much larger than those of the IBM SiGe HBT, and the distribution of charge buildup in KT9041 is several orders of magnitude greater than that of the IBM SiGe HBT. The result suggests that the simulations are consistent with the experiment, and indicates that the geometry of the EB-spacer, the area of the Si/SiO_2 interface and the isolation structure could be contributing to the different ionizing radiation damage.     

Three-dimensional simulation of fabrication process-dependent effects on single event effects of SiGe heterojunction bipolar transistor

The fabrication process dependent effects on single event effects(SEEs) are investigated in a commercial silicon–germanium heterojunction bipolar transistor(SiGe HBT) using three-dimensional(3D) TCAD simulations. The influences of device structure and doping concentration on SEEs are discussed via analysis of current transient and charge collection induced by ions strike. The results show that the SEEs representation of current transient is different from representation of the charge collection for the same process parameters. To be specific, the area of C/S junction is the key parameter that affects charge collection of SEE. Both current transient and charge collection are dependent on the doping of collector and substrate. The base doping slightly influences transient currents of base, emitter, and collector terminals. However, the SEEs of SiGe HBT are hardly affected by the doping of epitaxial base and the content of Ge.     

不同偏置影响锗硅异质结双极晶体管单粒子效应的三维数值仿真研究

针对国产锗硅异质结双极晶体管(SiGe HBT),采用半导体器件三维计算机模拟工具,建立单粒子效应三维损伤模型,研究不同偏置状态对SiGe HBT单粒子效应的影响.分析比较不同偏置下重离子入射器件后,各端口电流瞬变峰值和电荷收集量随时间的变化关系,获得SiGe HBT单粒子效应与偏置的响应关系.结果表明:不同端口对单粒子效应响应的最劣偏置不同,同一端口电荷收集量和瞬变电流峰值的最劣偏置也有所差异.载流子输运方式变化和外加电场影响是造成这种现象的主要原因.     

锗硅异质结晶体管单粒子效应激光微束模拟

对国产锗硅异质结双极晶体管(SiGe HBT)进行了单粒子效应激光微束辐照试验,观测SiGe HBT单粒子效应的敏感区域,测试不同外加电压和不同激光能量下SiGe HBT集电极瞬变电流和电荷收集情况,并结合器件结构对试验结果进行分析。试验结果表明:国产SiGe HBT位于集电极/衬底结内的区域对单粒子效应敏感,波长为1064 nm的激光在能量约为1.5 nJ时诱发SiGe HBT单粒子效应,引起电流瞬变。入射激光能量增强,电流脉冲增大,电荷收集量增加;外加电压增大,电流脉冲的波峰增大;SiGe HBT的单粒子效应与外加电压大小和入射激光能量都相关,电压主要影响瞬变电流的峰值,而电荷收集量主要依赖于入射激光能量。     

重离子导致的锗硅异质结双极晶体管单粒子效应电荷收集三维数值模拟

针对国产锗硅异质结双极晶体管(SiGe HBTs), 采用半导体器件模拟工具, 建立SiGe HBT单粒子效应三维损伤模型, 研究影响SiGe HBT单粒子效应电荷收集的关键因素. 分析比较重离子在不同位置入射器件时, 各电极的电流变化和感生电荷收集情况, 确定SiGe HBT电荷收集的敏感区域. 结果表明, 集电极/衬底结内及附近区域为集电极和衬底收集电荷的敏感区域, 浅槽隔离内的区域为基极收集电荷的敏感区域, 发射极收集的电荷可以忽略. 此项工作的开展为下一步采用设计加固的方法提高器件的抗辐射性能打下了良好的基础. 关键词： 锗硅异质结双极晶体管 单粒子效应 电荷收集 三维数值仿真     

超低泄漏电流二极管单粒子位移损伤电流计算

提出了一种计算超低泄漏电流硅二极管的单粒子位移损伤电流的方法。采用SRIM软件计算了252Cf源的裂变碎片入射二极管产生的初级撞出原子的分布, 并采用Shockley-Read-Hall复合理论探讨了单粒子位移损伤电流值与缺陷参数的关系, 计算了252Cf源辐照引起的单粒子位移损伤电流台阶值, 计算结果与实验结果一致。针对耗尽区电场非均匀的特点, 提出电场分层近似方法来考虑处于耗尽区中不同位置的初级撞出原子产生的缺陷对泄漏电流的影响。结果表明, PN结附近电场增强载流子产生效应最显著, 考虑电场增强效应的情况下单个Frenkel缺陷引起的泄漏电流比未考虑电场增强效应时高约44倍;裂变碎片80 MeV Nd入射比106 MeV Cd入射引起的单粒子位移损伤电流大;252Cf源的裂变碎片在二极管中引起的单粒子位移损伤电流台阶值主要集中于1 fA至1 pA之间。     

Synergistic effect of total ionizing dose on single event effect induced by pulsed laser microbeam on SiGe heterojunction bipolar transistor

The synergistic effect of total ionizing dose(TID) on single event effect(SEE) in SiGe heterojunction bipolar transistor(HBT) is investigated in a series of experiments. The SiGe HBTs after being exposed to 60 Co g irradiation are struck by pulsed laser to simulate SEE. The SEE transient currents and collected charges of the un-irradiated device are compared with those of the devices which are irradiated at high and low dose rate with various biases. The results show that the SEE damage to un-irradiated device is more serious than that to irradiated SiGe HBT at a low applied voltage of laser test. In addition, the g irradiations at forward and all-grounded bias have an obvious influence on SEE in the SiGe HBT, but the synergistic effect after cutting off the g irradiation is not significant. The influence of positive oxide-trap charges induced by TID on the distortion of electric field in SEE is the major factor of the synergistic effect. Moreover, the recombination of interface traps also plays a role in charge collection.