ICSE2006 Proc, 2006, Kuala Lumpur, Malaysia.
Characterization of Strained Silicon MOSFET Using
Semiconductor TCAD Tools
Wong Yah Jin, Ismail Saad and Razali Ismail
Faculty of Electrical Engineering,
Universiti of Teknologi Malaysia,
81300 Skudai, Johor, Malaysia.
Email: helommi(igmalxom ismail s(ums.edu.myand razal(i0<e.utm.mY
Abstract - The paper is looking into the
enhancement of conventional PMOS by
incorporating a strained silicon within the
channel and bulk of semiconductor. A detailed
2D process simulation of Strained Silicon
PMOS (SSPMos) and its electrical
characterization was done using TCAD tool
[1].
With the oxide thickness, Tox of 16nm and
Germanium concentration of 35%, the
threshold voltage Vt for the strained Si and
conventional PMOS is -0.5067V and -0.9290V
respectively. This indicates that the strained
silicon had lower power consumption. Beside
that, the drain induced barrier lowering
(DIBL) value for the strained PMOS is
0.3034V and the conventional PMOS is
0.4747V, which shows a better performance
for strained silicon as compared to
conventional PMOS. In addition, the output
characteristics were also obtained for SSPMos
which showed an improvement of Drain
current compared with conventional PMOS.
I. INTRODUCTION
Scaling down of MOSFET devices has been the
driving force in IC industry in order to achieve
higher speed and lower power requirements [2].
The recent MOSFET devices have been scaled
down to 50nm gate lengths where the gate oxide
thickness has become thin enough to suppress the
short channel effect (SCE) [3]. However further
scaling down of the MOSFET beyond 50nm will
cause the SCE to intensify, thus degrading the
current drivability and electron mobility of a
MOSFET [4]. The continuous downsizing of the
gate length have caused the gate oxide to become
so thin that current begins to leak across the gate
even when there is no applied voltage. Therefore
further improvement without minimizing the gate
length is strongly required. Carrier mobility
improvement has been seen as one of the best
alternative for faster devices at lower power
levels [5]. Strained silicon technology can offer
significant performance enhancement to
MOSFET devices [6] by increasing carrier
mobility without having to make the devices
become smaller [7], [8]. By stressing or
straining, the silicon lattice lets electrons flow
with less resistance. This will increase the drive
current and make the transistor switch faster thus
contributing to a higher clock frequency in
integrated circuits (IC) with gate length
downsizing to 60nm [9]. Another significant
improvement in electrical performance for both n
and p-channel device of strained Si with 25% Ge
composition is demonstrated in [10]. In this
paper we will study the performance
enhancement by strained silicon as compared to
conventional PMOS comprehensively with the
help of Silvaco TCAD process and device
simulation tools. With the Tox of 16nm and 35%
of Ge concentration, the VT for the strained Si
and conventional PMOS is -0.5067V and -
0.9290V respectively. The drain induced barrier
lowering (DIBL) for the SSPMOS is 0.3034V
and the conventional PMOS is 0.4747V, which
shows a better performance for strained silicon as
compared to conventional PMOS. Consequently,
the output characteristics were also obtained for
SSPMos that showed an improvement of Drain
current compared with conventional PMOS.
II. DEVICE STRUCTURE AND PROCESS
Both strained silicon PMOS with an added SiGe
layer and normal conventional PMOS device
without SiGe layers process simulation were
carried out using ATHENA, Figure 1 shows the
structure of both devices. The simulation process
to create the strain silicon PMOS is similar to the
conventional PMOS fabrication process. The
fabrication of SSPMOS device starts by creating
a silicon substrate with phosphorus doping of 2 x
1018 cm-3 and then a silicon layer with the
thickness of 0.018ptm is deposited on the silicon
0-7803-9731-2/06/$20.00 ©2006 IEEE
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