Design and optimization of Ge profiles for improved thermal stability of SiGe HBTs

• Published in: Journal of semiconductors Vol. 34; no. 6; pp. 44 - 48
• Main Author: 付强 张万荣 金冬月 丁春宝 赵彦晓 张瑜洁
• Format: Journal Article
• Language: English
• Published: 01.06.2013
• Subjects: Cut-off; Fingers; Gain; Germanium; HBT; Semiconductors; SiGe; Silicon germanides; Temperature profiles; Trapezoids; 优化; 异质结双极型晶体管; 异质结双极晶体管; 温度依赖性; 热稳定性; 设计
• ISSN: 1674-4926
• DOI: 10.1088/1674-4926/34/6/064001

The impact of the three state-of-the-art germanium（Ge） profiles（box,trapezoid and triangular） across the base of SiGe heterojunction bipolar transistors（HBTs） under the condition of the same total amount of Ge on the temperature dependence of current gainβand cut-off frequency f_T,as well as the temperature profile,are investigated.It can be found that although theβof HBT with a box Ge profile is larger than that of the others,it decreases the fastest as the temperature increases,while theβof HBT with a triangular Ge profile is smaller than that of the others,but decreases the slowest as the temperature increases.On the other hand,the f_T of HBT with a trapezoid Ge profile is larger than that of the others,but decreases the fastest as the temperature increases,and the f_T of HBT with a box Ge profile is smaller than that of the others,but decreases the slowest as temperature increases.Furthermore,the peak and surface temperature difference between the emitter fingers of the HBT with a triangular Ge profile is higher than that of the others.Based on these results,a novel segmented step box Ge profile is proposed,which has modestβand f_T,and trades off the temperature sensitivity of current gain and cut-off frequency,and the temperature profile of the device.