A31: Low Temperature Characteristics and Transportin Advanced MOS Transistors

amountdollElectronics - Devices

Nov 2, 2013 (3 years and 9 months ago)

81 views

A31: Low Temperature Characteristics and Transport

in Advanced MOS Transistors


Wipa Chaisantikulwat, IMEP

Institut de Microélectronique, Electromagnétisme et Photonique (CNRS
-
INPG
-
UJF)


The channel length reduction in MOS transistors is necessary in order

to
ensure progressive device scaling. To better understand the carrier transport
mechanisms in these devices, low temperature characteristics allows us to study
physical phenomena that are enhanced or suppressed at these temperatures such
as the effects
of interface or bulk defects, the role of scattering mechanisms. The
temperature reduction also results in an increase of the carrier mobility, better turn
-
on
capabilities, lower power consumption which could improve the device and circuit
performances.


This lab work aims to demonstrate static MOSFET measurements using a
cryogenic probe station capable of holding a 200 mm wafer, and of testing down to
liquid Helium temperature. The chuck and probe heads are operated from outside the
cryogenic platform, an
d manipulation under cryogenic temperature works as under
standard conditions. Statics characteristics of the transistors at low temperatures will
be obtained. A classical static extraction method will be used to extract electrical
parameters such as the t
hreshold voltage, subtreshold slope, and the low field
mobility. The latter is a crucial parameter in assessing the performance of MOSFET’s
in the deep submicron regime as have already been shown in several works. The
determination of the low field mobilit
y at low temperatures allows us to separate the
contributions of phonons from the effects of interface or channel defects/impurities,
and to analyze the transport in the channel. The

subthreshold swing improvement,
and the magnitude of the threshold voltag
e shift would indicate whether the device
could be suitable for low temperature operation.




Experimental set
-
up

Typical transfer characteristics I
d
(V
g
) and g
m
(V
g
)

of a FDSOI device with L
g
=0.6

m for various temperatures.