J. SAINT MARTIN, V. AUBRY-FORTUNA, A. BOURNEL, P. DOLLFUS,

1
Influence Of Ballistic Effects In Ultra-Small
MOSFETs

• J. SAINT MARTIN, V. AUBRY-FORTUNA, A. BOURNEL, P.
  DOLLFUS,
• S. GALDIN, C. CHASSAT
• stmartin_at_ief.u-psud.fr

INSTITUT D'ÉLECTRONIQUE FONDAMENTALE

IEF, UMR CNRS 8622, Université Paris Sud,

F-91405 ORSAY cedex FRANCE
Centre scientifique d'Orsay
- Bât. 220





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Contents

• Introduction
• Channel length and ballistic transport
• Bias dependence on ballisticity
• Ballisticity and long-channel effective mobility

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Contents

• Introduction
• Channel length and ballistic transport
• Bias dependence on ballisticity
• Ballisticity and long-channel effective mobility

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Transport in decanano MOSFET
Front gate
Scattering counting region
y
0
Source
Drain
Back gate
Entrance
Exit
Quasi-ballistic transport electron mean free
path is similar to Lch

• Bint of ballistic electrons at the drain-end
• Beff

Monte Carlo simulation
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Contents

• Introduction
• Channel length and ballistic transport
• Bias dependence on ballisticity
• Ballisticity and long-channel effective mobility

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Studied devices
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From quasi-stationary to quasi-ballistic
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Ballisticity and channel length
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Ballisticity and current
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Beff(Bint) in undoped channels
Decreasing impact of Bint on Beff
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Contents

• Introduction
• Channel length and ballistic transport
• Bias dependence on ballisticity
• Ballisticity and long-channel effective mobility

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Bint as a function of VDS for different VGS
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Sta-bal and bal-sta architectures
sta
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Bint (VDS) sta-bal vs. bal-sta
Higher phonon scattering rate gt driving field
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Contents

• Introduction
• Channel length and ballistic transport
• Bias dependence on ballisticity
• Ballisticity and long-channel effective mobility

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Studied strained SGMOS
LG 25 nm
V. Aubry-Fortuna et al.,to be published

• x increase
• Strain increase
• mt population increase
• ?eff enhancement

Tox 0.7 nm
SiO2
21020 cm-3
21020 cm-3
LG 18 nm
TSi 10 nm
Strained Si 1.21019 cm-3
1.21019 cm-3
Si1-xGex (P) Pseudo substrate
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Ion(Bint) vs. Ion(?eff)

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Conclusions

• Connections between Bint and
• channel length
• strain
• bias
• High quasi ballistic influence for Bint lt 20
• Bint more relevant than µeff to account for Ion
• Role of MOS architecture (cf. paper)