1. College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124, China;
2. College of Physics, Liaoning University, Shenyang 110036, China

A technique for simultaneously improving the product of cutoff frequency-breakdown voltage and thermal stability of SOI SiGe HBT

1. College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124, China;
2. College of Physics, Liaoning University, Shenyang 110036, China

The product of the cutoff frequency and breakdown voltage (f_{T}×BV_{CEO}) is an important figure of merit (FOM) to characterize overall performance of heterojunction bipolar transistor (HBT). In this paper, an approach to introducing a thin N^{+}-buried layer into N collector region in silicon-on-insulator (SOI) SiGe HBT to simultaneously improve the FOM of f_{T}×BV_{CEO} and thermal stability is presented by using two-dimensional (2D) numerical simulation through SILVACO device simulator. Firstly, in order to show some disadvantages of the introduction of SOI structure, the effects of SOI insulation layer thickness (T_{BOX}) on f_{T}, BV_{CEO}, and the FOM of f_{T}×BV_{CEO} are presented. The introduction of SOI structure remarkably reduces the electron concentration in collector region near SOI substrate insulation layer, obviously reduces f_{T}, slightly increases BV_{CEO} to some extent, but ultimately degrades the FOM of f_{T}×BV_{CEO}. Although the f_{T}, BV_{CEO}, and the FOM of f_{T}×BV_{CEO} can be improved by increasing SOI insulator SiO_{2} layer thickness T_{BOX} in SOI structure, the device temperature and collector current are increased due to lower thermal conductivity of SiO_{2} layer, as a result, the self-heating effect of the device is enhanced, and the thermal stability of the device is degraded. Secondly, in order to alleviate the foregoing problem of low electron concentration in collector region near SOI insulation layer and the thermal stability resulting from thick T_{BOX}, a thin N^{+}-buried layer is introduced into collector region to not only improve the FOM of f_{T}×BV_{CEO}, but also weaken the self-heating effect of the device, thus improving the thermal stability of the device. Furthermore, the effect of the location of the thin N^{+}-buried layer in collector region is investigated in detail. The result show that the FOM of f_{T}×BV_{CEO} is improved and the device temperature decreases as the N^{+}-buried layer shifts toward SOI substrate insulation layer. The approach to introducing a thin N^{+}-buried layer into collector region provides an effective method to improve SOI SiGe HBT overall performance.

The product of the cutoff frequency and breakdown voltage (f_{T}×BV_{CEO}) is an important figure of merit (FOM) to characterize overall performance of heterojunction bipolar transistor (HBT). In this paper, an approach to introducing a thin N^{+}-buried layer into N collector region in silicon-on-insulator (SOI) SiGe HBT to simultaneously improve the FOM of f_{T}×BV_{CEO} and thermal stability is presented by using two-dimensional (2D) numerical simulation through SILVACO device simulator. Firstly, in order to show some disadvantages of the introduction of SOI structure, the effects of SOI insulation layer thickness (T_{BOX}) on f_{T}, BV_{CEO}, and the FOM of f_{T}×BV_{CEO} are presented. The introduction of SOI structure remarkably reduces the electron concentration in collector region near SOI substrate insulation layer, obviously reduces f_{T}, slightly increases BV_{CEO} to some extent, but ultimately degrades the FOM of f_{T}×BV_{CEO}. Although the f_{T}, BV_{CEO}, and the FOM of f_{T}×BV_{CEO} can be improved by increasing SOI insulator SiO_{2} layer thickness T_{BOX} in SOI structure, the device temperature and collector current are increased due to lower thermal conductivity of SiO_{2} layer, as a result, the self-heating effect of the device is enhanced, and the thermal stability of the device is degraded. Secondly, in order to alleviate the foregoing problem of low electron concentration in collector region near SOI insulation layer and the thermal stability resulting from thick T_{BOX}, a thin N^{+}-buried layer is introduced into collector region to not only improve the FOM of f_{T}×BV_{CEO}, but also weaken the self-heating effect of the device, thus improving the thermal stability of the device. Furthermore, the effect of the location of the thin N^{+}-buried layer in collector region is investigated in detail. The result show that the FOM of f_{T}×BV_{CEO} is improved and the device temperature decreases as the N^{+}-buried layer shifts toward SOI substrate insulation layer. The approach to introducing a thin N^{+}-buried layer into collector region provides an effective method to improve SOI SiGe HBT overall performance.

(Semiconductor-device characterization, design, and modeling)

基金资助:

Project supported by the National Natural Science Foundation of China (Grant Nos. 61574010, 60776051, 61006059, and 61006044), the Beijing Municipal Natural Science Foundation, China (Grant No. 4142007), and the Beijing Municipal Education Committee, China (Grant No. KM200910005001).

通讯作者:
Qiang Fu
E-mail: ffqqdudu@126.com

引用本文:

付强, 张万荣, 金冬月, 赵彦晓, 王肖. A technique for simultaneously improving the product of cutoff frequency-breakdown voltage and thermal stability of SOI SiGe HBT[J]. 中国物理B, 2016, 25(12): 124401-124401.
Qiang Fu, Wan-Rong Zhang, Dong-Yue Jin, Yan-Xiao Zhao, Xiao Wang. A technique for simultaneously improving the product of cutoff frequency-breakdown voltage and thermal stability of SOI SiGe HBT. Chin. Phys. B, 2016, 25(12): 124401-124401.

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