Product specifications

6
• Setup Matrix Switch
Figure 12 is the matrix switch setup
dialog box, which allows you to
easily control the matrix switches.
Click cross point boxes of switch-
ings to close. This example setup is
for the gate-substrate capacitance
of a MOSFET. CMH is connected
to the substrate terminal and CML
is connected to gate.
• Invert Bias Polarity
Transform Editor enables you to
define functions to calculate data
vectors or parameters. We apply
reverse staircase voltages to sub-
strate in C-V measurement. So it
is necessary to calculate the differ-
ence of potential between gate and
substrate by defining a function as
shown in Figure 13. In this example,
gate voltage is defined as VGATE
vector. You can define any other
functions to analyze measured data
too in this dialog box.
• Subtract Offset Capacitance
Measure offset capacitance of probe
card and/or probe needles. Move
probe needles off wafer so needles
are not connected to anything. After
sweeping substrate voltages, open
data window spreadsheet and deter-
mine average offset capacitance
value as shown in Figure 14.
C_COMP shows the compensated
offset capacitance vector data.
Then enter the negative average
value of offset capacitance in the
B field in E5250A C Compensation
dialog as shown in Figure 15. In
this example, average offset capaci-
tance was 2.337 pF.
• C-V Measurement
Perform C-V measurement of
Gate-Substrate capacitor. Contact
the probe needles on the wafer,
then measure. A graph of compen-
sated capacitance value versus
gate voltage will be drawn in a plot
window. An example measurement
result is shown in Figure 16. The
Agilent E5250A Matrix Switch only
adds an additional 1% error so you
can perform accurate capacitance
measurements even when using
the matrix.
Automated Test Using Agilent ICS
Agilent ICS enables you to automate
your tests. You can have multiple
measurement setups in one project
of ICS. By using the Auto Sequence
function, you can sequentially perform
selected measurements. Figure 17
shows the Auto Sequence dialog box
to define sequence of tests. In this
example, the project has five meas-
urement setups and four setups are
selected to be executed. Using this
function with E5250A matrix switch,
you can automate tests including
IV and C-V measurements.
Figure 16. C-V measurement example
Figure 14. Data window
Figure 15. Register offset cap
Figure 13. Transform editor