Design And Simulation Of SGOI Strained Si/SiGe HBT

Compared with traditional silicon transistors and III-V compound devices,SiGe HBT has the characteristics of low power consumption,low cost and compatibility with silicon-based process.SiGe BiCMOS technology combines the excellent performance of SiGe HBT with mature CMOS technology,which makes the application fields of SiGe HBT and their circuits wider.The introduction of strained Si technology and SOI technology can further improve current gain,frequency characteristics and radiation resistance,etc.Therefore,SGOI strained Si/SiGe HBT is analyzed,designed and simulated in this paper.Firstly,based on the physical properties and energy band characteristics of strained Si/SiGe materials,the working principle and basic characteristics of SiGe HBT are analyzed.Among them,current gain?,early voltage V_A,cut-off frequency f_T and other performance parameters are the focus of research.The different distribution forms of Ge profiles in base regions of SiGe HBT and their effects on the performance of devices are analyzed,which provides a theoretical basis for subsequent device design.Secondly,considering the process integration with SOI strained Si/SiGe heterojunction dual channel CMOS devices,a SGOI SiGe HBT mesa structure and its process flow are designed based on non-selective epitaxy technology.Silvaco TCAD software is used to simulate the process of the device,and the electrical and frequency characteristics of the device are simulated and analyzed.Compared with conventional SiGe HBT,the current gain?of SGOI SiGe HBT increases by about 27 times,the early voltage product?×V_A increases by about 17 times,and the cut-off frequency f_T increases by 39.9%.The influence of SGOI SiGe HBT on the current characteristics of devices with or without sub-collector is simulated and analyzed.Based on the different distribution forms of base Ge profiles,the effects of different Ge profiles and their distribution forms on device performance are simulated and analyzed.The results show that when base Ge profiles are triangular distribution,?is 717,?×V_A is 1.52×10~5V and f_T is 227 GHz;when base Ge profiles are trapezoidal distribution,?reaches 2230,?×V_A reaches 4.46×10~5V and f_T reaches 236 GHz.It can be concluded that the Ge profile in SGOI SiGe HBT base region is trapezoidal distribution,and its comprehensive performance index is better than that in the case of uniform distribution and triangular distribution,which can give full play to the advantages of devices.Finally,considering the process integration with SOI strained Si channel CMOS devices,a SGOI SiGe HBT planar structure is designed based on the selective epitaxy process under the condition of trapezoidal distribution form of base Ge profiles.The structure model of SGOI SiGe HBT planar device is realized by process simulation,and the electrical and frequency characteristics of the device are simulated and analyzed.The results show that the comprehensive performance index of SGOI SiGe HBT planar structure is slightly lower than that of mesa structure,and the planar structure technology is relatively complex,but it is easy to integrate with traditional strained Si channel CMOS.