应变Si沟道nMOSFET阈值电压模型

Threshold voltage model of strained Si channel nMOSFET

在研究分析弛豫SiGe衬底上的应变Si沟道nMOSFET纵向电势分布的基础上,建立了应变Si nMOSFET阈值电压模型,并利用该模型对不同的器件结构参数进行仿真,获得了阈值电压与SiGe层掺杂浓度和Ge组分的关系、阈值电压偏移量与SiGe层中Ge组分的关系、阈值电压与应变Si层掺杂浓度和厚度的关系.分析结果表明:阈值电压随SiGe层中Ge组分的提高而降低,随着SiGe层的掺杂浓度的提高而增大;阈值电压随应变Si层的掺杂浓度的提高而增大,随应变Si层厚度增大而增大.该模型为应变Si器件阈值电压设计提供了重要参考.

The model of nMOSFET threshold voltage was established based on study of voltage distribution in strained Si film, which was grown on relaxed SiGe virtual substrate. The model was analyzed with reasonable parameters, and the dependence of threshold voltage on Ge fraction and channel doping was revealed. The dependence of threshold voltage shift on Ge fraction was also obtained. The relationship between threshold voltage and strained Si layer thickness and doping was studied. The results indicates, the threshold voltage increases with increasing doping concentrations of relaxed SiGe layer, decreases with increasing Ge fraction of relaxed SiGe layer, and increases with increasing strained Si layer thickness. This threshold voltage model provides valuable reference to the strained-Si device design.