Modeling of U-shaped and plugged emitter resistance of high speed SiGe HBTs

Author

Cheng, Peng ; Dahlstrom, Mattias ; Liu, Qizhi ; Gray, Peter ; Adkisson, James ; Zetterlund, Bjorn ; Pekarik, John ; Camillo-Castillo, Renata ; Radic, Ljubo ; Ellis-Monaghan, John ; Harame, David

Author_Institution

IBM Microelectron. Div., Essex Junction, VT, USA

fYear

2011

fDate

9-11 Oct. 2011

Firstpage

154

Lastpage

157

Abstract

In this paper, we investigate the emitter resistance R_e in SiGe HBTs with speeds up to 280GHz, using a U-shaped polysilicon emitter. We observed that R_e increased with lateral scaling, thereby degrading f_T. Although a negligible component in the past, in this experiment R_e * C_cb transit time delay is playing a more significant role in limiting f_T. R_e was modeled to explain the increase due to lateral scaling, and was shown to result from the plugging of the emitter opening by the emitter polysilicon. Furthermore, process experiments were conducted to investigate the effect of emitter polysilicon thickness, sidewall height, and emitter i-layer thickness.

Keywords

Ge-Si alloys; delays; heterojunction bipolar transistors; semiconductor device models; SiGe; U-shaped emitter resistance; emitter i-layer thickness; emitter polysilicon thickness; high speed HBT; lateral scaling; plugged emitter resistance; sidewall height; transit time delay; Analytical models; Contact resistance; Plugs; Resistance; Silicon; Silicon germanium; Thickness measurement;

fLanguage

English

Publisher

ieee

Conference_Titel

Bipolar/BiCMOS Circuits and Technology Meeting (BCTM), 2011 IEEE

Conference_Location

Atlanta, GA

ISSN

1088-9299

Print_ISBN

978-1-61284-165-6

Type

conf

DOI

10.1109/BCTM.2011.6082770

Filename

6082770