Test and Measurement
allow the cables to be connected in parallel. This
An added
means that cables do not have to be added or
removed when changing from one measurement
benefit of
type to another; they can simply be moved from
one set of instrument connections to another.
having short
Given that most fast pulse instruments
require a 50Ω pathway, the parallel combination
cables near
of cables should yield 50Ω, so each cable must
have a characteristic impedance of 100Ω. Most
the DUT is
LCR/C-V meters are designed to function with
Issue VIII 2009
50 Figure 11: A pulsed I-V measurement setup
that it’s
square4
Ω cables, but the Keithley Model 4210-CVU
instrument for the Model 4200-SCS system is
possible to
.com
designed for use with 100Ω cables, resulting in
slightly improved C-V results.
short
Advantages
The main advantage of Keithley’s new approach
together the
to connecting the instrumentation to the prober
is that, no matter which type of measurement is
terminals of
oasiasemiconductor
being made, no changes to the probe
.eur
manipulator cabling are required.
a DUT that
www
This makes it much simpler to switch
between I-V measurements, C-V measurements, Figure 12: A four-terminal C-V measurement in
function at
29
and pulsed testing, simplifying the device which three of the four terminals are connected
characterization process. In addition, the setup together for a two-terminal C-V measurement
frequencies
changes can be made while the probe needles
up to or
are in contact with a wafer, reducing pad
damage and maintaining the same
greater than
contact impedance for all three types of
measurements.
1MHz
Many I-V and pulse measurements are made
on devices with more than two terminals.
The most common device type is a four-terminal
MOSFET. Figure 10 illustrates an I-V
measurement setup for a four-terminal DUT.
The connectors can be disconnected and
Figure 9: To insert a shorting cap, add shorting caps inserted into the source and bulk
connectors in the cables near the probe cables to allow making a pulse measurement.
manipulator mounts Figure 11 illustrates a pulsed I-V measurement
setup.
An added benefit of having short cables
near the DUT is that it’s possible to short
together the terminals of a DUT that function at
frequencies up to or greater than 1MHz. Figure
12 shows a four-terminal C-V measurement in
which three of the four terminals are connected
together to allow making a two-terminal C-V
measurement.
The frequency at which the C-V
measurement can be made can be increased by
Figure 10: An I-V measurement setup for a four- connecting the three terminals together at the
terminal DUT prober rather than at the LCR/C-V meter.
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