Transcript Leakage current of active device

Leakage current of device
HEMT versus MOSFET
2005-21482
이진식
Outline
MDCL

Introduction

HEMT

MOSFET

conclusion
Jin Sik Lee
introduction

Nowadays leakage power dissipation is a big issue




MDCL
According to aggressive scaling of CMOS with higher
integration density
Scaled device results in the drastic increase of total
leakage power
It degrades the performance of device
We must minimize the leakage current
Jin Sik Lee
HEMT

Leakage current


MDCL
Gate leakage current
Off state IDSleakage current
Jin Sik Lee
Gate leakage current




MDCL
C has very high leakage current
Leakage current affect the power gain and noise performance
With a short distance, heavy doping, high leakage current is
occurred
Wide band-gap semiconductor under the gate must be of highest
quality to form low leakage current
Jin Sik Lee
AlGaN-GaN:surface defect
Fixed positive charge

RF and power electronics



Schottky gate leakage

Fig 1.electric field concentration at the edge

High carrier mobility
High breakdown voltage
In reality10-5 order, it ideally
must be 1uA/mm
The influence of the surface
charge upon the gate leakage
current is modeled


Process damage such as
nitrogan vacancy
Inducing large tunneling current
Fig 2.schottky barrier thinning
MDCL
Jin Sik Lee
AlGaN-GaN:surface defect


Fig 4.AlGan-GaN HEMT with surface damaged
positive defect charge
increases the electric
field
With the increase of
defect charge



leakage current increase
Low breakdown voltage
Field plate electrode
structure

Uniformly distributed field
Fig 5.Sumulated off-state curve
MDCL
Jin Sik Lee
AlGaN-GaN:surface defect


MDCL
FP devices have lower
gate leakage current
compared to the no-FP
device
The influence of the
defect charge decreases
with the increase of FP
length
Jin Sik Lee
AlGaN-GaN:copper gate
I-V characturistics of a Cu
and a Ni/Au Schottky contact





gate leakage current under drain 0.1V and 10v
for a Cu gate and a Ni/Au gate
Copper gate AlGaN/GaN with low gate leakage
Schottky barrier height of Cu on n-GaN is 0.18eV higher than NiAu
Gate resistance of copper is 60% as that of NiAu
Low leakage, low resistivity, good adhesion for gate metal for power
device.
Resistivity:1.7uΏ/cm,
MDCL
Jin Sik Lee
Low standby leakage current


Enhancement-mode JPHEMT with a high VF



E-mode junction
pseudomorphic HEMT
with a high Vth
High turn-on voltage
VF(1.3V)at 1mA/mm
Single power supply PA
When the Vth is near
VF,gate current increases.
Key Point:high VF(1.3v)
IGS-VGS characteristic of the conventional
and the novel JPHET
MDCL
Jin Sik Lee
MOSFET



Subthreshold leakage
current
Gate leakage current
R-biased band-toband leakage current
Figure 1.Major leakage components
MDCL
Jin Sik Lee
MOSFET



MDCL
Relative leakage components
becomes equally important
For 90-nm, the major
leakage components is the
subthreshold.
In the scaled device,
contribution of junction and
gate leakage have
significantly increased
Jin Sik Lee
Subthreshold leakage current
Ids

Log(Ids) scale
Linear Ids scale





Vth
Vg
SS=2.3*kt/q(1+Cdm/Cox)
Independent of Vds
The effect of trap density
Halo doping method
Practically it is a function of
temperature

MDCL
Slight dependent on cons
dVt/dT~-1mV/k
Jin Sik Lee
Subthreshold leakage current

gate
N+
N+
P+
Halo(pocket) implant doping method
is choosed to improve not only
subthreshold leakage current but
also short channel effect or
something

P+

HALO
p-sub

MDCL
Localized implant doping is done
near source/drain
The higher doping reduces the
source/drain. depletion widths and
prevents their interaction such as
charge sharing, DIBL
disadvantge:BTBT leakage current
Jin Sik Lee
Gate leakage current

As gate length becomes more smaller, thin oxide
thickness is also needed





MDCL
Short channel effect
There is a constraint to meet the requirements that people
want
As tox becomes thin, tunneling leakage current may
happen
High k material such as HfO2is studied broadly
Impact ionization
Jin Sik Lee
conclusion

Leakage current is a big issue



HEMT


MDCL
Surface defect, Gate material
MOS


It degrades the performance of device
It dissipates unnecessary power
Subthreshold, gate, BTBT
It is important to minmize the leakage current considering
other points
Jin Sik Lee
Reference

Subthreshold leakage modeling and reduction techniques [IC CAD tools]
Kao, J.; Narendra, S.; Chandrakasan, A.;
Computer Aided Design, 2002. ICCAD 2002. IEEE/ACM International Conference on
10-14 Nov. 2002 Page(s):141 - 148

Accurate estimation of total leakage in nanometer-scale bulk CMOS circuits based on device
geometry and doping profile
Mukhopadhyay, S.; Raychowdhury, A.; Roy, K.;
Computer-Aided Design of Integrated Circuits and Systems, IEEE Transactions on
Volume 24, Issue 3, March 2005 Page(s):363 - 381

Modeling subthreshold leakage and thermal stability in a production life test environment
Black, K.; Kelly, K.; Wright, N.;
Semiconductor Thermal Measurement and Management Symposium, 2005 IEEE Twenty First Annual IEEE
15-17 March 2005 Page(s):223 - 228

Off-state breakdown effects on gate leakage current in power pseudomorphic AlGaAs/InGaAs HEMTs
Chou, Y.C.; Li, G.P.; Chen, Y.C.; Wu, C.S.; Yu, K.K.; Midford, T.A.;
Electron Device Letters, IEEE
Volume 17, Issue 10, Oct. 1996 Page(s):479 - 481
MDCL
Jin Sik Lee