acq_ex09 : Capacitance Calibration, De-embedding and Measurement
Requires: Utmost IV, SmartSpice, SmartView
Minimum Versions: Utmost IV 1.10.6.R, SmartSpice 4.10.6.R, SmartView 2.28.2.R
This example describes how to perform capacitance measurements including
calibration and de-embedding.
The project file
for this example should be loaded into your database. When opened, the
project will look as shown in
This project is already set up to measure a diode capacitance using the measurement
setup as shown in
. In this measurement setup, the cathode is connected to the Hi terminals of the LCR
instrument and the anode connected to the Lo terminals. Therefore, positive bias from
the LCR instrument (V_LCR) will reverse bias the diode.
In the hardware dialog, the LCR instrument is enabled as shown in
. The LCR instrument provides the DC bias for this measurement internally.
In the connections dialog, shown in
, you can see the connection for this capacitance measurement. The bias on
the Hi terminals is supplied by the LCR instrument itself. The LCR
instrument also has a virtual ground on the Lo terminals, therefore no
DC instrument is required to supply the zero volts ground on the anode.
In the connection, the anode is set to 'manual:GND' to indicate that this
ground is already taken care of.
When measuring any capacitance, you should calibrate or zero the LCR
instrument to remove the effect of the test instrument, cables, probes,
test structure, etc. from the measured result. If you have a dedicated
open calibration structure, this should be used when calibrating the
To calibrate the LCR instrument, select the capacitance measurement setup
in the measurement sequence and then select
from the menu. This will open the calibration and de-embedding dialog as shown in
For capacitance measurements, we only need to perform the open correction
to the LCR instrument. Clicking on the
button will open up
LCR Open Short Calibration
dialog. From this dialog, clicking the
button will perform the instrument calibration. This may take several minutes
depending on the LCR instrument. When the calibration completes sucessfully,
this is indicated on the dialog as shown in
Some older equipment does not have a calibration option. In this case, you
should perform a de-embedding measurement on the open structure. This
measured open data will then be subtracted from the device result automatically
when you perform the measurement. To perform an open de-embedding measurement,
. Then select the open device structure and click on the
button in the dialog. When the open de-embedding measurement
is completed, this will be displayed in the calibration dialog
as shown in
Another reason you may need to use the de-embedding feature is if you have
a problem with your test structure. If, after calibation, you measure the
open structure and it has a significant bias dependent capacitance over
the voltage range you want to measure, then you can use open de-embedding
to correct for this in the device measurement.
Note that when you are using the de-embedding feature, you must
before closing the calibration dialog, otherwise the de-embedding measurement
will be lost.
Once you have performed your calibration to zero the LCR instrument and, if
necessary, have performed the open de-embedding measurement, you are now ready
to measure the device capacitance characteristic. This is done by selecting
from the menu to run the measurement sequence as normal. If you have selected
to perform open de-embedding, the open data will be automatically subtracted
from the device capacitance measurement.