SECONDARY-ION MASS-SPECTROSCOPY ULTRASHALLOW DEPTH PROFILING FOR SI SI1-XGEX/SI HETEROJUNCTION BIPOLAR-TRANSISTORS/

Citation
D. Kruger et al., SECONDARY-ION MASS-SPECTROSCOPY ULTRASHALLOW DEPTH PROFILING FOR SI SI1-XGEX/SI HETEROJUNCTION BIPOLAR-TRANSISTORS/, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 14(1), 1996, pp. 287-293
Citations number
28
Categorie Soggetti
Physics, Applied
ISSN journal
10711023
Volume
14
Issue
1
Year of publication
1996
Pages
287 - 293
Database
ISI
SICI code
1071-1023(1996)14:1<287:SMUDPF>2.0.ZU;2-9
Abstract
Starting from a theoretical dopant and composition profile of a Si/Si1 -xGex/Si heterojunction bipolar transistor (HBT), the requirements for high depth resolution secondary ion mass spectroscopy (SIMS) measurem ents are discussed. To characterize the boron out-diffusion from the S i1-xGex base, which can crucially degrade the transit frequency f(T), a depth resolution of better than about 3 nm is necessary. SIMS measur ements have been performed using low energy oxygen primary beams at no rmal incidence to characterize sharp B profiles in Si and Si1-xGex lay ers. Graded Ge concentrations have been measured quantitatively using cesium primary beams and MCs(+) secondary ion detection. It is shown t hat in the limit of low energy primary beams, the leading edges of the SIMS profiles with upslopes of 1-2 nm/decade show sufficient resoluti on for many of the HBT applications. For better characterization of ef fects which are located on the trailing edge of the profile, deconvolu tion procedures are necessary. (C) 1996 American Vacuum Society.