Impact of surface roughness on silicon and Germanium ultra-thin-body MOSFETs

Tony Low, M. F. Li, W. J. Fan, S. T. Ng, Y. C. Yeo, C. Zhu, Albert Chin, L. Chan, D. L. Kwong

Research output: Contribution to journalConference article

32 Citations (Scopus)

Abstract

Ultra-thin body (UTB) SOI MOSFET is promising for sub-50 nm CMOS technologies [1]. However, recent experimental finding [2] suggests the need for serious reconsiderations of its long-term scaling capability into the sub-10 nm body thickness (T BODY) regime. Two new phenomena attributed to surface roughness (SR) are identified [2]; they are enhanced threshold voltage (V TH) shifts and drastic degradation of mobility with a T BODY dependence [2,3]. In this work, we detail a study of these two phenomena in UTB MOSFETs with sub 10 nm T BODY Si and Ge channels. Firstly, the phenomena of enhanced V TH shifts is modeled by accounting for the fluctuation of quantized energy levels due to SR up to second order approximation. Good corroboration with experimental results [2] is obtained. Our model is then applied to examine the impact of enhanced V TH shifts on metal gate workfunction requirements. Secondly, we modeled the SR-limited electron and hole mobility and discuss their impact on the choice of surface orientations. Mobility anisotropy are also examined for the various surface orientations.

Original languageEnglish (US)
Pages (from-to)151-154
Number of pages4
JournalTechnical Digest - International Electron Devices Meeting, IEDM
StatePublished - Dec 1 2004
EventIEEE International Electron Devices Meeting, 2004 IEDM - San Francisco, CA, United States
Duration: Dec 13 2004Dec 15 2004

Fingerprint

thin bodies
Germanium
Silicon
germanium
surface roughness
field effect transistors
Surface roughness
shift
silicon
Hole mobility
Electron mobility
SOI (semiconductors)
hole mobility
Threshold voltage
electron mobility
threshold voltage
Electron energy levels
CMOS
Anisotropy
energy levels

Cite this

Impact of surface roughness on silicon and Germanium ultra-thin-body MOSFETs. / Low, Tony; Li, M. F.; Fan, W. J.; Ng, S. T.; Yeo, Y. C.; Zhu, C.; Chin, Albert; Chan, L.; Kwong, D. L.

In: Technical Digest - International Electron Devices Meeting, IEDM, 01.12.2004, p. 151-154.

Research output: Contribution to journalConference article

Low, T, Li, MF, Fan, WJ, Ng, ST, Yeo, YC, Zhu, C, Chin, A, Chan, L & Kwong, DL 2004, 'Impact of surface roughness on silicon and Germanium ultra-thin-body MOSFETs', Technical Digest - International Electron Devices Meeting, IEDM, pp. 151-154.
Low, Tony ; Li, M. F. ; Fan, W. J. ; Ng, S. T. ; Yeo, Y. C. ; Zhu, C. ; Chin, Albert ; Chan, L. ; Kwong, D. L. / Impact of surface roughness on silicon and Germanium ultra-thin-body MOSFETs. In: Technical Digest - International Electron Devices Meeting, IEDM. 2004 ; pp. 151-154.
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AU - Low, Tony

AU - Li, M. F.

AU - Fan, W. J.

AU - Ng, S. T.

AU - Yeo, Y. C.

AU - Zhu, C.

AU - Chin, Albert

AU - Chan, L.

AU - Kwong, D. L.

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N2 - Ultra-thin body (UTB) SOI MOSFET is promising for sub-50 nm CMOS technologies [1]. However, recent experimental finding [2] suggests the need for serious reconsiderations of its long-term scaling capability into the sub-10 nm body thickness (T BODY) regime. Two new phenomena attributed to surface roughness (SR) are identified [2]; they are enhanced threshold voltage (V TH) shifts and drastic degradation of mobility with a T BODY dependence [2,3]. In this work, we detail a study of these two phenomena in UTB MOSFETs with sub 10 nm T BODY Si and Ge channels. Firstly, the phenomena of enhanced V TH shifts is modeled by accounting for the fluctuation of quantized energy levels due to SR up to second order approximation. Good corroboration with experimental results [2] is obtained. Our model is then applied to examine the impact of enhanced V TH shifts on metal gate workfunction requirements. Secondly, we modeled the SR-limited electron and hole mobility and discuss their impact on the choice of surface orientations. Mobility anisotropy are also examined for the various surface orientations.

AB - Ultra-thin body (UTB) SOI MOSFET is promising for sub-50 nm CMOS technologies [1]. However, recent experimental finding [2] suggests the need for serious reconsiderations of its long-term scaling capability into the sub-10 nm body thickness (T BODY) regime. Two new phenomena attributed to surface roughness (SR) are identified [2]; they are enhanced threshold voltage (V TH) shifts and drastic degradation of mobility with a T BODY dependence [2,3]. In this work, we detail a study of these two phenomena in UTB MOSFETs with sub 10 nm T BODY Si and Ge channels. Firstly, the phenomena of enhanced V TH shifts is modeled by accounting for the fluctuation of quantized energy levels due to SR up to second order approximation. Good corroboration with experimental results [2] is obtained. Our model is then applied to examine the impact of enhanced V TH shifts on metal gate workfunction requirements. Secondly, we modeled the SR-limited electron and hole mobility and discuss their impact on the choice of surface orientations. Mobility anisotropy are also examined for the various surface orientations.

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