Switching Between C-V and I-V
Measurements Using the 4200A-CVIV
Multi-Switch and 4200A-SCS
Parameter Analyzer––
APPLICATION NOTE

Switching Between C-V and I-V Measurements Using the4200A-CVIV Multi-Switch and 4200A-SCS Parameter Analyzer

APPLICATION NOTE

Introduction

4200A-CVIV Operation

Full parametric characterization of a semiconductor device

The 4200A-CVIV Multi-Switch is a four-channel multiplexed

usually requires an array of tests to gather all of the device’s

switching accessory for the 4200A-SCS that allows users

important parameters. Current-voltage (I-V) tests are used

to switch seamlessly between I-V and C-V measurements.

to determine device parameters like transfer characteristics,

It accepts four SMUs, one for each channel, and one

leakages, and breakdown voltages. Capacitance-voltage

CVU as inputs. Changing the output mode for each of(C-V) tests are used to determine device parameters likethe four channels reconfigures the internal switches of

doping concentrations, interface charges, and thresholdthe 4200A-CVIV to route the desired signals to the output

voltages. It is very common to perform both I-V and C-V tests

terminals. Figure 2 shows a simplified switching diagram ofon the same device, but the two test types require different

the 4200A-CVIV.

test equipment and cabling. These differences make it
difficult to perform I-V and C-V measurements on the same

SMU1

device quickly because changing test types typically requires

CVHI

recabling the entire system.
When configured with 4200-SMU or 4210-SMU Source

CVLO
CV GUARD

Measure Units (SMUs) and the 4210-CVU Capacitance

SMU2

Voltage Unit, the 4200A-SCS Parameter Analyzer is capableof performing both I-V and C-V measurements. However,the SMUs use triaxial cables and the CVU uses SMA coaxial

Channel 1

Channel 2

INPUTSOUTPUTS

cables. Combining the 4200A-SCS Parameter Analyzer withthe 4200A-CVIV Multi-Switch eliminates these difficulties
because the 4200A-CVIV is capable of switching between

SMU3

Channel 3

I-V and C-V measurements with no need to change cables
or lift probe tips. The 4200A-CVIV is shown in Figure 1. The
Clarius software that runs on the 4200A-SCS makes it simple
to control the Multi-Switch and creates a faster, more efficientdevice testing workflow for any application that requires

SMU4

Channel 4

making I-V and C-V measurements on the same device.

Figure 2. A simplified switching diagram for the 4200A-CVIV. All of thechannels are shown in two-wire mode and in the OPEN position.

The 4200A-CVIV has five different output modes foreach channel:• SMU – The SMU signal paths in the 4200A-CVIV are notmultiplexed and cannot be switched between channels.
Each SMU channel is directly associated with the channel
to which it is connected. For example, setting Channel 3
to SMU will pass the signal from the SMU connected to
Channel 3 to the output terminals for Channel 3.
Figure 1. The 4200A-CVIV Multi-Switch.

2 | WWW.TEK.COM• CV HI and CV LO – The CVU signal path in the4200A-CVIV is fully multiplexed and can be assigned
to any of the output channels. CV HI or CV LO can be
assigned to any channel or any combination of channels

Switching Between C-V and I-V Measurements Using the4200A-CVIV Multi-Switch and 4200A-SCS Parameter Analyzer

APPLICATION NOTE

to perform the desired C-V measurement. For example,

The cviv-configure Action is used to switch the channel

setting Channel 1 to CV HI and Channels 2 and 3 to

output configuration, two-wire/four-wire CVU setting, and

CV LO will configure the Multi-Switch to perform a C-V

the names of the test and channels to be shown on themeasurement on the device connected between Channel

4200A-CVIV display. A cviv-configure Action must be used

1 and Channels 2/3.

any time the configuration of the 4200A-CVIV needs to• CV GUARD – This mode of the 4200A-CVIV can beused to remove undesired capacitances from C-V
measurements. The CVU guard is the outside shield of
the CVU coaxial cable. For example, setting Channel 4
to CV GUARD will configure the Multi-Switch to guard
out capacitance from the device terminal connected to
Channel 4.
• OPEN – Configuring any channel to OPEN will open all of
the output relays connected to that channel.
The 4200A-CVIV is controlled using the Clarius softwarechange. Figure 3 shows an example of the cviv-configure
Action populated with settings to switch the CVU output
terminals to a MOSFET.
The cvu-cviv-comp-collect Action performs CVU
connection compensation through a 4200A-CVIV ona user-defined configuration. Open, Short, and Loadcorrection compensations can be acquired. Connection
compensation corrects for offset and gain errors caused by
the connections between the CVU and the device under test.
The compensation for each particular switch configuration is
automatically stored so that when a particular configuration

application that comes with the 4200A-SCS Parameteris recalled using the cviv-configure Action, the compensation

Analyzer. Switch configurations are controlled by placing

will automatically be applied if it is enabled within a C-V

the cviv-configure Action from the Action Library into themeasurement test. Figure 4 shows the cvu-cviv-comp-project tree.

collect Action setup to perform an Open compensation.

Figure 3. The cviv-configure Action options.

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Switching Between C-V and I-V Measurements Using the4200A-CVIV Multi-Switch and 4200A-SCS Parameter Analyzer

APPLICATION NOTE

Figure 4. The cvu-cviv-comp-collection Action configured to perform an Open Compensation.

Figure 5 shows a screen capture of a project called Diode
Tests that is used to make I-V and C-V measurements
on a diode that is connected to the outputs of Channels
1 and 2. First, compensation is performed using the
cvu-cviv-comp-collect Action. Then the cviv-configure-iv
Action connects SMU1 and SMU2 to Channels 1 and 2 sothat the forward and reverse I-V measurements can be madein the two tests that follow. When the cviv-configure-cv Action
is executed, the SMUs are disconnected from the outputs
and the CVU HI and LO terminals are connected to Channels
1 and 2. Finally, a C-V sweep is made on the diode.

Figure 5. The project tree structure for a diode test that uses the4200A-CVIV to switch between I-V and C-V measurements

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Switching Between C-V and I-V Measurements Using the4200A-CVIV Multi-Switch and 4200A-SCS Parameter Analyzer

APPLICATION NOTE

C-V/I-V Switching for Device
Characterization

4200A-CVIV

Both I-V and C-V measurements play a role in the parametric

4-Wire Modecharacterization of semiconductor devices. Two-terminal
devices require simple I-V sweeps to characterize their DC
performance and C-V sweeps to determine the capacitance
between their two terminals at different bias levels. For
example, full characterization of a diode requires I-V
measurements to acquire the forward I-V curve, reverse
leakage curve, and reverse breakdown voltage. C-V
measurements are used to acquire the diode’s doping profileand charge density information.

Two-terminal Devices

Channel 4
OPEN
Channel 3
OPEN
Channel 2
SMU
Channel 1
SMU

Sense

Force
Sense
Force
Sense
Force
Sense

If
+

Cd

-

Force

Vf

Two channels of the 4200A-CVIV are used to connect to thediode for I-V and C-V measurements. Since diodes havevery low impedance forward active characteristics, it’s bestpractice to perform measurements in four-wire mode toprevent measurement inaccuracies due to losses in cabling.
Four-wire mode, also called remote sense, forces a test
current through one set of cables and measures a voltage
directly at the device under test with another set of cables.
This technique helps remove the effects of cable impedancefrom the measurements.

Figure 6. Configuration for I-V characterization of a diode using the4200A-CVIV.

The gray capacitor in Figure 6 (Cd) is the parasitic
capacitance of the PN junction. The I-V test does not provide
information about this parasitic capacitance. A C-V test isnecessary to characterize the capacitance of the device.
Figure 7 shows the device connections and 4200A-CVIV
settings for a C-V test on a diode. All of the connections are
identical to the I-V test. When the cviv-configure Action is

Figure 6 shows the device connections and 4200A-CVIV

executed in the Clarius software, the output is switched fromsettings for an I-V test on a diode. All of the DC I-V

the SMUs to the CVU terminals.

characteristics of the diode are collected in this configuration.
The connections to the diode are made with triaxial cables,
Model 4200-TRX-.75 (75cm or approximately 30 inches).
These shielded cables are used to ensure that both very
low current I-V measurements and high frequency AC
measurements can be made with high accuracy. The device
can be a packaged part in a test fixture or located directly ona wafer in a probe station.

4200A-CVIV
4-Wire Mode
Channel 4
OPEN
Channel 3
OPEN
Channel 2
CVHI
Channel 1
CVLO

Sense
Force
Sense
Force
Sense

Force
Sense
Force

If + Iac

Cd+-

Vf + Vac

Figure 7. Configuration for C-V characterization of a diode using the4200A-CVIV.

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Switching Between C-V and I-V Measurements Using the4200A-CVIV Multi-Switch and 4200A-SCS Parameter Analyzer

APPLICATION NOTE

Three-terminal Devices

C bc

Three-terminal devices require more complicated I-V

Collector

characterization and often capacitance measurements
between multiple combinations of terminals. For example,

Basebipolar junction transistors (BJTs) are three-terminal devices

Ccethat require multiple SMUs to measure their transfer
characteristics and produce useful data, such as Gummel

C beplots. The 4200A-CVIV, when coupled with three 4200-SMUs

Emitteror 4210-SMUs and the 4210-CVU in the 4200A-SCS, canmake these measurements.

Figure 9. Parasitic capacitances of a bipolar junction transistor (BJT).

Figure 8 shows the device connections, and 4200A-CVIV

To measure the capacitance between two terminals, it issettings, for an I-V test on a BJT. The configuration is shown

necessary to guard the third terminal to remove the effects

in two-wire mode, also known as local sense, but remoteof the additional parasitic capacitors. For example, tosensing should be used for high current BJTs. All of themeasure the base-emitter capacitance (Cbe,), the collector

connections to the BJT are made with the 4200-TRX-.75

is connected to guard. The 4200A-CVIV provides thistriaxial cables. The device can be a packaged part in a test

guard signal with the CV GUARD setting. Figure 10 shows

fixture or located directly on a wafer in a probe station.

the cviv-configure settings that instruct the 4200A-CVIV
to use the CV GUARD signal. In this example, the CV HI
terminal is connected to base (b) through Channel 2, CV LO

4200A-CVIV

is connected to the emitter (e) through Channel 1, and CV

2-Wire Mode

GUARD is connected to the collector (c) through Channel 3.

Channel 4
OPEN
Channel 3
SMU
Channel 2
SMU
Channel 1
SMU

Sense
Force
Sense

Ic

Force
Sense
Force
Sense

Ib

+
-

Vce

Force

Figure 8. Configuration for I-V characterization of a BJT using the4200A-CVIV.

Figure 10. cviv-configure settings for a base-emitter capacitancemeasurement on a BJT.

Once the I-V measurements are complete, the 4200A-CVIV

Figure 11 shows the device connections, and 4200A-CVIV

can be seamlessly switched to measure the parasitic

settings, for a guarded capacitance measurement on thecapacitances of the BJT junctions without changing cables

Cbe of a BJT.

or removing connections to the device. Figure 9 shows
the parasitic capacitances between the BJT’s terminals tobe measured.

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Switching Between C-V and I-V Measurements Using the4200A-CVIV Multi-Switch and 4200A-SCS Parameter Analyzer

APPLICATION NOTE

4200A-CVIV

4200A-CVIV

2-Wire Mode

2-Wire Mode

Channel 4
OPEN
Channel 3
CV GUARD
Channel 2
CVHI
Channel 1
CVLO

Sense
Force
Sense
Force
Sense
Force
Sense

Force

Sense

Channel 4
OPEN

GuardedChannel 3
CV GUARD

Iac

Channel 2
CVHI

+
Vac
-

C be

Channel 1
CVLO

Force
Sense
Force
Sense
Force
Sense

Force

Id
+

Vds
-

+
Vgs
-

Figure 11. Base-emitter capacitance measurement on a BJT using the4200A-CVIV.

Figure 12. I-V characterization of a four-terminal MOSFET using the4200A-CVIV.

The same technique is used to measure the base-collector

Capacitance measurements are often made on MOSFETs

capacitance or the collector-emitter capacitance of the BJT.

to explore their basic operation and various parameters.

The 4200A-CVIV can be controlled by the Clarius software

Given that the high frequency operation and switching

to make all of these measurements automatically without

speeds of a MOSFET are dependent on the capacitance ofmoving cables between the terminals. The Clarius software

the device, capacitance measurements are often made on

includes a project (cvu-bjt-cviv) that is configured to measurevarious parasitic capacitances of the device, as shown inthese three parasitic capacitances present in a BJT using the

Figure 13. For example, the capacitance between the gate

4210-CVU and the 4200A-CVIV to switch the CVU between

and channel (Cgd and Cgs) is important because it createsterminals of the device.

the charges necessary for operating the devices. This gatechannel capacitance depends on the applied voltage and theFour-terminal Devices

operating region.

Four-terminal devices, such as a MOSFET with a separate
bulk connection, have more terminal-to-terminal parasitic
capacitances, and more potential I-V and C-V measurement

Cgd

Drain
Cgb

Cbd

combinations than lower terminal count components. The
4200A-CVIV, when fully configured with four SMUs andone CVU, addresses these measurements with flexible

Gate

Bulk

configurability.
Figure 12 shows the device connections, and 4200A-CVIV
settings, for an I-V test on a four-terminal MOSFET. The
configuration is shown in two-wire mode, also known as
local sense, but remote sensing should be used for high

Cgs

C bs
SourceFigure 13. Parasitic capacitances of a MOSFET.

current MOSFETs. All of the connections to the MOSFET aremade with 4200-TRX-.75 triaxial cables. The device can be a
packaged part in a test fixture or located directly on a wafer
in a probe station.

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Switching Between C-V and I-V Measurements Using the4200A-CVIV Multi-Switch and 4200A-SCS Parameter Analyzer

APPLICATION NOTEThe C-V characteristics of the capacitor formed between thegate and the source, drain, and bulk of the MOSFET structure
can be used to determine characteristics of the MOSFET likethe threshold voltage, oxide thickness, oxide capacitance,and doping density. Figure 14 shows the most common way
of configuring this measurement. The source, drain, and bulk
terminals are physically tied together and a C-V sweep isperformed between the gate and the other three terminals.

HICUR
HIPOT

4210CVU

2-Wire Mode
Channel 4
CVLO
Channel 3
CVLO
Channel 2
CVHI

D
G

4200A-CVIV

B
S

Channel 1
CVLO

LOCUR
LOPOT

Figure 14. C-V test configuration for a MOSFET.

removes the need to tie the source, drain, and bulk together
physically at the device to perform this measurement;
instead, the connections are made internal to the4200A-CVIV. Figure 15 shows the device connections, and4200A-CVIV settings, for this C-V test on a four-terminal

Force
Sense
Force
Sense
Force
Sense
Force

Iac
+
-

Vdc+VacFigure 15. C-V characterization of a four-terminal MOSFET using the4200A-CVIV.

The CVHI, CVLO, and CV GUARD signals of the 4200A-CVIV
can each be assigned to more than one pin at a time. This

Sense

CVHI
4200ACVIV
CVLO

Internally connectedby the 4200A-CVIV

D
G
B

S

MOSFET. Channels 1, 3, and 4 are all assigned to CVLO inthis configuration. Figure 16 shows the equivalent circuit ofthis 4200A-CVIV configuration.

Figure 16. 4200A-CVIV two-terminal MOSFET C-V test
equivalent circuit.

Conclusion
The 4200A-CVIV Multi-Switch makes it easy to perform I-V
and C-V measurements on the same device without the needto change cables, which could potentially introduce errors or
damage devices. The 4200A-SCS and Clarius software makeit simple to control the 4200A-CVIV and integrate C-V and I-V
testing together into a single project that executes seamlessly
and continuously.

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Switching Between C-V and I-V Measurements Using the4200A-CVIV Multi-Switch and 4200A-SCS Parameter Analyzer

APPLICATION NOTE

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