Research On A Novel Structure Of Strained Si/SiGe HBT For BiCMOS Integration

Since the working frequency of modern communication systems moves towards THz,there is a higher demand for the processing speed of signals in communication systems and for the development of core semiconductor devices with high frequency characteristics.Firstly,a strain Si/SiGe HBT architecture is designed by employing the embedded silicon-germanium(SiGe)technology commonly used in the strained PMOS device.The device performance is improved by applying uniaxial compressive stress to the current direction by implanting the Si_1-yGe_ystress raisers in the collector and altering the energy-band structure to reduce the effective mass of the carrier at the top of the valence band,thereby increasing the carrier longitudinal mobility and reducing the transit time in the base and collector.Secondly,SILVACO TCAD tools have been to used for device simulation and performance verification,and the effect of Ge fraction y on the main performance parameters such as peak current gain?_max,Early voltage V_A,characteristic frequency f _T,maximum oscillation frequency f_maxand breakdown voltage BV_CEOunder the conditions of different Ge fraction configuration in the Si_1-xGe_xbase.The simulation results exhibit that the best performance of the proposed strain Si/SiGe HBT,listed as?_max=6060,V_A=397.7V,f _T=535.2GHz,f_max=734GHz and BV_CEO=1.25V,can be obtained under the conditions of 25%?30%step-state configured Ge fraction in the Si_1-xGe_xbase and 10%uniform Ge fraction in the Si_1-yGe_ystress raisers.The product of current gain and Early voltage,?×V_A,and the Johnson's limit,f _T×BV_CEO,reached 2.4×10⁶V and6.69×10¹¹Hz·V,respectively.Eventually,the manufacturing process of a strain Si/SiGe HBT BiCMOS inverter is designed by combining advanced CMOS processes and BiCMOS processes,the process simulation tools are then used to develop the architecture of the strain Si/SiGe HBT BiCMOS inverter,and investigate the influence of Ge fraction in the Si_1-xGe_xsource/drain of the strain PMOS transistors and that in the Si_1-yGe_ystress raisers of the proposed SiGe HBT on the voltage transfer curve(VTC)of the BiCMOS inverter.The simulation results show that the logic threshold voltage,V_M,decreases with the increase of varied Ge fraction in the inverter.When that Ge fraction in both source/drain and stress raisers varies up to 30%,the inverter now has the best conversion efficiency.However,taking account to the process integration and circuit application,the performance of the proposed BiCMOS inverter achieved the best when the Ge component is set by 15%.This work may have some certain reference value and engineering significance for the development of silicon-based high speed/high frequency devices and circuits.