Product specifications

3
Maximum lengths for triaxial and
coaxial cables are 3 m and 2 m,
respectively.
The Agilent P/N 8120-4461 coaxial
cable has a semiconductor layer to
minimize the triboelectricity generat-
ed by frictional motion at boundary
between the conductor and insulator.
This special design enables you to
perform accurate dc measurements
through this cable as well as capaci-
tance measurement.
To connect this cable to the connec-
tor plate, it is necessary to isolate the
inner conductor from the semicon-
ductor layer. To do this, cut the semi-
conductor layer and insulator as
shown in Figure 4. Then solder inner
conductor to force terminal of a triax-
ial connector and outer conductor to
guard terminal.
Note that dangerous voltage may
appear at the force and guard termi-
nals. To prevent electric shock, cover
the triaxial connectors with metal
cover. Install an interlock circuit to
stop dangerous voltages when door
of shield box is open.
Capacitance compensation is per-
formed based on F matrix calculation
for matrix and cables. Predetermined
values of residual impedance and
stray admittance per cable length are
used. Therefore, if you use other than
recommended cables, compensation
cannot be performed correctly.
Figure 5 shows measurement circuit
diagram of Agilent 4284A including
matrix switch and cables. The connec-
tor plate is used as a part of return
path for the measurement signal cur-
rent. The compensation calculation is
performed assuming the outer shield
of triaxial cables are connected to each
other at connector plate as shown in
Figure 5. If you use a connector plate
other than Agilent 16495A/B, such as
a connector plate that has an insulator
between the outer shields of the triaxial
connectors, the compensation may be
incorrect.
As for the necessary instruments and
accessories, refer to Table 1. Ordering
Example, on page 8.
Device Connection
When connecting LCR meter to meas-
urement capacitors on semiconductor
wafers, you need to take the device
structure and LCR meter’s measure-
ment circuit into account.
Because the ammeter is in the low side
of the circuit, as shown in Figure 5,
LCR meter’s low terminal is more
sensitive to noise than the high ter-
minal. Therefore, for example, con-
nect the high terminal to the wafer
chuck of prober or to the substrate
terminal on wafer, which generally has
wider antenna area to gather noise
than small gate area in case of oxide
capacitance measurements. For more
tips, please refer to Tips for More
Accurate Capacitance Measurements.
Common
Guard
Force
Triaxial Connector
Inner conductor
Insulator
Semiconductor layer
Outer conductor
Jacket
Agilent 16495F/G Option 002 Agilent 8120-4461 Low Noise
Connector Plate Coaxial Cable
Figure 4. Soldering coax cable to the Agilent 1645A/B connector plate
V
A
Agilent 4284A
H cur
H pot
L cur
L pot
Agilent 5250A
Matrix switch
Agilent 16495F/G
Connector plate
High
Low
Wafer
Wafer chuck
Noise
Figure 5. Connection of high and low terminals