金属系统对SiGe HBT自热效应的影响  

Impact of Metal System on Self-Heating Effect of SiGe HBT’s

作　　者：刘庆[1] 张伟[1] 许军[1] 

机构地区：[1]清华大学微电子学研究所,北京100084

出　　处：《微电子学》2005年第4期332-335,339,共5页Microelectronics

基　　金：国家高技术研究发展计划"RF电路模块和相关关键实现技术研究"资助项目(2002AA1Z1610)

摘　　要：在SiGeHBT设计中,采用AlTiNTi多层金属系统,可减小基极电阻,提高器件的频率和功率特性(fmax)。但是,本文的研究表明,如果忽略了发射极电阻的减小和TiN、Ti有较小的热导率,而不在设计中做出适当调整,在相同的大电流工作条件下,多层金属HBT的输出特性在自热效应和能带调节共同作用下,将会表现出明显的负阻效应。分析其原因1)由于发射极接触电阻减小,即等效的HBT发射极镇流电阻减小,使得器件调节自热效应的能力减弱;2)由于多层金属中TiN和Ti热导率较低,在相同条件下,器件通过金属连线均衡温度分布的能力变差,与Al系统相比,其BE结温度更高。在大电流工作条件下,较差的自热效应调节能力和较高的结温使得多层金属HBT的值减小较快,器件的频率和功率特性变差。In designing SiGe HBT, multilayer metal Al-TiN-Ti system can reduce base resistance and improve the device power and frequency characteristics. Experimental results show that, compared with single AI system,the contact resistance of muhilayer metal system is reduced remarkably. But, if the emitter resistance decrease and weaker heat conductance of TiN and Ti is ignored during design, the output characteristics of HBT＇s with multilayer metal system, affected by both self-heating and energy-band modulation, will become worse, compared to H BT＇s with Al system. The reasons are： first, the decrease of emitter contact resistance weakens the ability of ballasting resistance to regulate the self-heating effect; second, the weaker heat conductance of multilayer system, in the same working conditions as Al system, makes the device＇s ability to equilibrium temperature distribution through the metal connectors worse.

关 键 词：SIGE HBT 多层金属结构 自热效应 输出特性 

分 类 号：TN304.24[电子电信—物理电子学] TN322.8