Research On Modeling And Simulation Of Si/SiGe HBT With Composite Strain

With the rapid development of modern mobile communications,medical and health technologies,there is an increasing demand for high-frequency performance of semiconductor devices in the market.However,modern silicon-based bipolar transistor devices cannot meet the performance requirements of high-speed,high-power integrated circuits.In order to meet the requirements of integrated circuits for device performance,a graded Ge component is introduced in the base of silicon-based bipolar transistors,namely,Si Ge Heterojunction Bipolar Transistor(Si Ge HBT).Combining Si Ge HBT devices with mature CMOS technology fundamentally solves the contradiction between increasing magnification and improving frequency characteristics,and becomes a breakthrough point for large-scale integrated circuits to pursue high-frequency,high-speed,and low-cost.Based on modern Si Ge HBT process technology,the research contents of this paper are as follows:Firstly,the Si Ge HBT device adopts a 90nm-CMOS process,and a novel composite strained Si Ge HBT structure that can be used in the terahertz band is designed and simulated.By growing Si Ge epitaxial layer in the base pseudocrystal and introducing biaxial strain,the energy band is split and the carrier mobility is improved.The ”embedded” Si Ge structure is adopted on both sides of the collector,and uniaxial strain is introduced while biaxial strain,which will effectively reduce the transmission time of carriers in the collector.Si Ge HBT becomes a standard bipolar transistor with high frequency and high speed.Secondly,TCAD simulation software is used to simulate the process flow and electrical characteristics of Si Ge HBT devices.By studying the effect of the combination of uniaxial strain and biaxial strain on device performance.An equivalent circuit model of a composite strained Si Ge HBT device with enhanced transport that can accurately reflect the physical nature of the device is established.The model will contain DC,large-signal and small-signal equivalent circuits.The model will effectively simulate the changes in the device equivalent circuit and its parameter model caused by the introduction of stress,and accurately simulate the DC characteristics of composite strain Si/Si Ge HBT devices And communication characteristics.Finally,the influence mechanism of material characteristics,composite strain and carrier mobility on the performance of the device is analyzed.Comparing the performance parameters of composite Si Ge HBT and conventional Si Ge HBT,it is found that the cut-off frequency of composite strain Si Ge HBT is increased by 6% and the maximum oscillation frequency is increased by 11 % compared with conventional Si Ge HBT.It is proved that silicon-based semiconductor technology can completely replace III-V technology in terahertz field and meet the requirements of high-speed and high-power integrated circuits for device performance.