The document discusses the short channel effect in field-effect transistors (FETs), particularly focusing on the challenges posed by miniaturization such as drain-induced barrier lowering and punch through. It highlights the importance of controlling electric fields in both vertical and horizontal dimensions to mitigate performance degradation in miniaturized devices. Additionally, the implementation of FinFET technology offers improved control over channel guidance, enhancing transistor performance compared to traditional planar designs.

1. Short channel effect on
FET
Peresentation by
Mahsa Fargharazi

2. HELLO !
I am Mahsa Farqarazi
I am a master of
nanotechnology at
Damghan University
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IN THE
NAME OF
GOD

4. CONTENTS
Introduction
History
Type of Field effect transistor
Limitations resulting from the size reduction
Short channel effect
Fin FET
Summary
References
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5. INTRODUCTION
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The field-effect transistor (FET) is a transistor that
uses an electric field to control the electrical behavior
of the device. FETs are also known as unipolar
transistors since they involve single-carrier-type
operation. Many different implementations of field
effect transistors exist. Field effect transistors
generally display very high input impedance at low
frequencies. The conductivity between the drain and
source terminals is controlled by an electric field in
the device, which is generated by the voltage
difference between the body and the gate of the
device

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8. History
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9. Short channel effect
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Channel length ~= depletion width of source and drain

10. “A MOSFET device is considered to be
short when the channel length is the same
order of as the channel length L is reduced
to increase both the operation speed and the
number of components per chip, the so
called short-channel effects arise.

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The short-channel effects are attributed to two physical phenomena:
The limitation
imposed on
electron drift
characteristics in
the channel The modification
of the threshold
voltage due to
the shortening
channel
length.

12. Limitations resulting from the size reduction
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shrinking channel length
the narrow channel width
the creation of strong field in the channel
Limits resulting from :

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In particular five different short-channel effects can be
distinguished:
Drain-induced
barrier lowering and
“Punch through”
Surface scattering Velocity saturation
Impact ionization Hot electrons

14. DRAIN INDUCE DBARRIER LOWERING (DIBL)
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.
• Increase in drain voltage reduces
the barrier face by electrons or
holes in the source allowing them
to go from source to drain where
gate voltage remain unchanged.
• Gate looses the control of flow
of current through MOS and
become as good as redundant.

15. “
Punch through
When the depletion regions surrounding the drain extends to the source,
so that the two depletion layer merge, punch trough occurs.
Punch through can be minimized with thinner oxides, larger substrate
doping, shallower junctions, and obviously with longer channels.

16. Surface scattering
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You may be wondering why this is a short-channel effect...
Indeed, as the length of the channel becomes shorter, the
lateral electric field created by VDS becomes stronger. To
compensate that, the vertical electric field created by the
gate voltage needs to increase proportionally, which can be
achieved by reducing the oxide thickness. As a side effect,
surface scattering becomes heavier, reducing the effective
mobility in comparison with longer channel technology
nodes

17. Velocity saturation
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• Up to certain point velocity is
directly proportional to electric field.
• But after the point velocity saturates
and has no effects of increase in
electric field.

18. Impact Ionization
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When an electron collides with an atom of the Silicon lattice structure, the energy passed to the
atom upon collision can knock out an electron out of the valence band to the conduction band,
creating an electron-hole pair. The hole is attracted to the bulk while the generated electron moves
on to the drain.

19. “
Holes flowing through the bulk create a voltage drop that may turn on the parasitic bipolar
transistor. When it turns on, electrons can flow to the bulk and drain by the BJT instead of
the channel created by the MOSFET

20. Hot electron
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 At high velocity carriers drifting near the drain
gains extra energy called hot carriers.
 These hot carriers tunnel through gate oxide
thus reducing the total current flow from source to
drain.
 Reduces the input impedance.
The implantation of lightly doped drains

21. Fin FET
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This state of the transistor creates the ability to
control the channel guidance in three directions
vertically, which makes controlling the flow of the
transistor far better than the planar transistors. The
reason for naming the FinFet name is the uplink
channel, in the sense that it is called a Fin because
of its rise, which is why it is called the Fin or the
Wing. It should be noted that the use of several Fin
contributes to the power of the transistor.

22. summery
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Short Channel Effects are governed by
complex physical phenomena and
mainly Influenced because of both
vertical and horizontal electric field
components.
To meet the current requirements of
Electronic devices, the miniaturization
of devices is important. And so is
Second Order effects which otherwise
degrade the performance of devices.

23. References
 Solid state electronic devices-Prentice-Hall series in solid state physical electronics -Ben G.
Streetman
 physical electronics and semiconductor Technologi-Akbar Adibi- Amirkabir Univercity of
Technologi
 Short-Channel Effects in MOSFETs -December 11th, 2000-Fabio D’Agostino -Daniele
Quercia
 http://www.onmyphd.com/?p=mosfet.short.channel.effects

24. Maps
Damghan
univercity
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THANKS!
Any questions?
You can find me at mahsa_fz85@yahoo.com
👉