Using the 4200-CVU-PWR C-V Power Package
to Make High Voltage and High Current
C-V Measurements with the 4200A-SCS
Parameter Analyzer––
APPLICATION NOTE

Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

Introduction
Traditional capacitance-voltage (C-V) testing ofsemiconductor materials is typically limited to about 30V

APPLICATION NOTE

measures the capacitance of the device under test (DUT). The
4205-RBT allows coupling of the AC signals from the CVU
and the DC signal from the SMU.

and 10mA DC bias. However, many applications, such as

In this setup, either the CVL1 (LPOT and LCUR) or CVH1

characterizing C-V parameters of LD MOS structures, low(HPOT and HCUR) can be connected to the AC Input ofinterlayer dielectrics, MEMs devices, organic TFT displays,

the bias tee. By default, the AC ammeter is connected toand photodiodes, require higher voltage or higher current

the CVL1 terminals and it is best that the AC ammeter be

C-V measurements. For these applications, a separate

connected to the gate of the device if applicable. If this is thehigh voltage DC power supply and a capacitance meter arecase, then the HCUR and HPOT (or CVH1) terminals of therequired to make the measurements.

4210-CVU are connected to the other side of the device or to

The 4200-CVU-PWR C-V Power Package for the 4200A-SCS
allows making C-V measurements with a DC voltage bias ofup to ±200V or 400V differential (0 to ±400V) and a current
output of up to 300mA. Using this package, the 4210-CVU
Capacitance-Voltage Unit measures the capacitance andeither one or two 4200-SMUs (or 4210-SMUs for current up
to 300mA) are used to supply the DC bias or sweep voltage.

the chuck. The DC bias is supplied by the 4200-SMU, with
the Force and Sense from the SMU connected to the Forceand Sense terminals of the bias tee. The SMU LO terminals
and the CVU CVH1 terminals are referenced internally to thesystem output common.
4210-CVU

The C-V Power Package includes two bias tees that enable

H CUR

coupling of the AC signals from the 4210-CVU and the DC

H POT

signals from the 4200-SMU. Along with the hardware, the C-V
Power Package includes interactive software to control thehigh voltage C-V measurements using the Clarius software.

L POT
L CUR

SMA Tee

DeviceUnder Test
SMA Cables

This application note explains how to implement and optimize
high voltage C-V tests using the 4200-CVU-PWR C-V Power
Package. It assumes the reader is familiar with making C-V

SENSE

CVU at the level outlined in [1] and [2].

FORCE

Making Connections To The Device
The 4200-CVU-PWR C-V Power Package comes with two

SMA
Tee

AC Input 4205-RBT

4200-SMU

measurements with the Keithley 4200A-SCS with the 4210-

C

Triax
Cables

SENSE
FORCE

AC & DC
OutputFigure 1. Device Connections for High Voltage C-V Measurements
Using One Bias Tee

4205-RBT Remote Bias Tees. The desired voltage output

For C-V measurements that require up to 400V differential,

will determine if one or two bias tees are required in the test

two 4205-RBT Remote Bias Tees and two 4200-SMUs are

circuit. For C-V measurements with an applied voltage bias

required in addition to the 4210-CVU Capacitance Voltage

up to ±200V, one bias tee is required. For C-V measurements

Unit. This configuration is shown in Figure 2. Using thiswith a voltage differential up to 400V (for example: 0 to 400V

configuration, 4200-SMU 1 and the CVL1 terminals of theor –100 to 300V), two bias tees are required.

4210-CVU are connected through one 4205-RBT Remote

To make C-V measurements with an applied voltage bias up
to ±200V, one 4200-SMU Source-Measure Unit, one 4210CVU Capacitance-Voltage Unit, and one 4205-RBT Remote
Bias Tee are connected to the device as shown in Figure 1.
The 4200-SMU sources the DC voltage and the 4210-CVU

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Bias Tee to one side of the device. The other side of thedevice is connected through a second 4205-RBT bias tee toboth the 4200-SMU 2 and the CVH1 terminals of the 4210CVU. This setup allows 400V differential measurements, forexample, 0 to 400V, –100 to 300V, or –400V to 0V.

Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

APPLICATION NOTE

4210-CVU
H CUR
H POT
L POT
L CUR

SMA Cables

SMA Cables

4200-SMU 1
SENSE
FORCE

Triax
Cables

SMA
Tee

SMA
Tee

AC Input 4205-RBTAC Input 4205-RBT

SENSE
FORCE

AC & DC
OutputDUT

AC & DC
Output

SENSE
FORCE

4200-SMU 2
Triax
Cables

SENSE
FORCE

Figure 2. High Voltage C-V Measurements Using Two Remote Bias Tees

Using the Clarius Software to Control
High Voltage C-V Measurements

In addition to the project, the Test Library includes several

The hivcvulib user library contains two modules, SweepV

However, these tests are examples and can be used on otherand CvsT, for controlling the high voltage C-V measurements.

devices as welltests for making high voltage C-V measurements on Zener
diodes, MOS capacitors, capacitors, and Schottky diodes.

These modules can be used with either the one or two bias
tee configurations.
Using one bias tee, the SweepV module allows the user tosweep a DC voltage across the DUT using the 4200-SMU
and measure the capacitance using the 4210-CVU. If two
bias tees are used with the SweepV module, then one SMU isused to sweep the DC voltage and the other SMU is used toapply an offset DC bias (as shown in Figure 2).
The CvsT module provides capacitance measurements as afunction of time at a user-specified DC bias. This module canalso be used with either one or two bias tees. With one bias
tee and one SMU, capacitance measurements can be madewith up to 200V DC bias. With two bias tees and two SMUs,
capacitance measurements can be made up to 400V DC.
These user modules can be opened up in a project byselecting a Custom Test from the Test Library. However,a project has already been created that uses these test
modules. This project, called High Voltage C-V Tests(cvu_highv) can be found in the Project Library by searchingon “high voltage C-V”. This project uses both the SweepVand CvsT users modules to make measurements on devices.

Setting up the Parameters in the SweepV Module
Table 1 lists the adjustable parameters for the SweepV
module. This module has settings for the 4210-CVU and up
to five 4200-SMUs in the test circuit. One SMU is used forthe voltage sweep in the C-V measurements. Up to four other
SMUs can be used to output a DC bias. One SMU can also
be used to measure current.
Here is a description of the input parameters:
OpenCompensate: If desired, an offset correction can be
performed. First, select Tools at the top of the screen andselect CVU Connection Compensation. Then select Measure
Open. After this compensation procedure is performed, it canbe enabled in this module by selecting the OpenCompensate
parameter in the Key Parameters pane.
ShortCompensate: For lower impedance devices, a shortcompensation should be performed. This is especially true
for the two bias tee configuration. First, short the CVH1
and CVL1 terminals. From Tools, select CVU Connection
Compensation and then select Measure Short. After thiscompensation procedure is performed, short compensation
can be enabled in the SweepV module by checking
ShortCompensate in the Key Parameters pane.

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Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

APPLICATION NOTE

Table 1. List of Adjustable Parameters in SweepV User Module
Parameter

Range

Description

OpenCompensate

0 or 1

Enables/Disables Open Compensation for CVU

ShortCompensate

0 or 1

Enables/Disables Short Compensation for CVU

CVUCableLen0, 1.5m, 3m

Set cable length for CVU

SweepSMU

1-8

SMU number that will force voltage in CV sweep

MeasISMU

1-8

SMU number that will measure current during the CV sweep

StartV–200 to +200

Start voltage for sweep

StopV–200 to +200

Stop voltage for sweep

StepV–200 to +200

Step voltage for sweep

SweepDelay

0 to 10 seconds

Time between voltage steps

PresoakV–200 to +200

Voltage bias prior to start of sweep

PresoakTime

0 to 600 seconds

Time to apply soak voltage

SMU1Bias–200 to +200

Voltage forced by SMU1 during sweep (ignored with SMU1 is SweepSMU)

SMU2Bias–200 to +200

Voltage forced by SMU2 during sweep (ignored with SMU2 is SweepSMU)

SMU3Bias–200 to +200

Voltage forced by SMU3 during sweep (ignored with SMU3 is SweepSMU)

SMU4Bias–200 to +200

Voltage forced by SMU4 during sweep (ignored with SMU4 is SweepSMU)

Frequency

10e3 to 10e6

Test frequency

ACVoltage

0.01 to 0.1V

AC test voltage of CVU

Speed

0 fast, 1 normal, 2 quiet

Speed of CVU

CVRange

0=Auto, 1µA, 30µA, 1mA

CVU measure range

CVUCableLen: Input the length of the CVU cables. By

StartV, StopV, StepV: Input the start, stop, and step size

default, this is set to 1.5m, the length of the SMA cables thatvoltages for the C-V sweep.

come with the 4210-CVU, Keithley P/N CA-447A.

SweepDelay: The time between steps in the voltage sweep.

SweepSMU: This is the number of the SMU that will force theAllow an adequate delay time to ensure the device reaches

sweep voltage in the C-V sweep. The Force HI and Sense HI

equilibrium. If measuring current through the bias tee,terminals of this SMU are connected to the Force and Sense

additional SweepDelay time may need to be added to ensureterminals of the 4205-RBT Remote Bias Tee.

optimal results.

MeasISMU: The user inputs the number of the SMU

PreSoakV: This is the voltage bias output by the SweepSMU

that will measure current in the circuit. If the SMU that isprior to the start of the voltage sweep.

measuring current is not the SMU that is used to sweep
voltage (SweepSMU), then the current range is set to limited
autorange to the 100nA range. If the SMU that is measuring
current is the same as the SweepSMU, then the current
range is set to limited autorange on the 10µA range. If thisis the case, additional sweep delay time needs to be added
to ensure a settled reading. It also may be necessary to
use PreSoakV and PreSoakTime to charge up the device
to the first step in the sweep prior to taking the current
measurements.

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PresoakTime: This is the length of the time in seconds for
the PreSoakV voltage to be applied to the device. You canverify how much time is required for the device to reachequilibrium by using the CvsT module in the hivcvulib. This
module measures the capacitance as a function of a time
while the device is biased with a constant DC voltage. The
settling time can be observed from the graph.

Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

APPLICATION NOTE

Table 2. List of Adjustable Parameters for CvsT User Module
Parameter

Range

Notes

OpenCompensate

0 or 1

Enables/Disables Open Compensation for CVU

ShortCompensate

0 or 1

Enables/Disables Short Compensation for CVU

CVUCableLen0, 1.5m, 3m

Set cable length for CVU

MeasISMU

1-8

SMU number that will measure current

SampleCount

1 to 10000

Number of Measurements

Interval

0 to 60

Time between readings

SMU1Bias–200 to +200

Voltage forced by SMU1SMU2Bias–200 to +200

Voltage forced by SMU2SMU3Bias–200 to +200

Voltage forced by SMU3SMU4Bias–200 to +200

Voltage forced by SMU4

Frequency

103 to 106

Test Frequency

ACVoltage

0.01 to 0.1V

AC test voltage of CVU

Speed

0 fast, 1 normal, 2 quiet

Speed of CVU

CVRange

0=Auto, 1µA, 30µA, 1mA

CVU measure range

SMU1Bias, SMU2Bias, SMU3Bias, SMU4Bias: In addition

Setting Up the Parameters in the CvsT Module

to an SMU supplying a voltage for the C-V sweep, up to four

Table 2 lists the adjustable parameters for the CvsT module.

more SMUs can be used to bias other parts of the test circuit.
Frequency: Test frequency of CVU, which can be set
to 10kHz, 20kHz, 30kHz, 40kHz, 50kHz, 60kHz, 70kHz,
80kHz, 90kHz, 100kHz, 200kHz, 300kHz, 400kHz, 500kHz,
600kHz, 700kHz, 800kHz, 900kHz, 1MHz, 2MHz, 3MHz,
4MHz, 5MHz, 6MHz, 7MHz, 8MHz, 9MHz, and 10MHz. For
higher capacitance values, the test frequency may need
to be lowered through the bias tee to avoid errors dueThis module has settings for the CVU and up to five SMUs
in the test circuit. One or two SMUs can be connected to
one or two bias tees to output voltage. It is not necessary to
specify which SMUs are connected to the bias tees. This isdone through the hardware configuration, and then the user
inputs in the test how much voltage those particular SMUs
will output. Two or three other SMUs can also output voltage
in the circuit. One SMU can be used to measure current.

to resonance.

Here is a description of the input parameters for the

ACVoltage: The amplitude of the AC voltage output

CvsT module:of the CVU.

OpenCompensate: If desired, an offset correction

Speed: The speed time can be set as: 0 = FAST, 1 =can be performed. First, select Tools and select CVU

NORMAL, and 2 = QUIET. The FAST mode has the fastest
time but the highest noise. The NORMAL mode is themost common setting, which allows sufficient settling
times for most measurements. The QUIET mode ensureshigh accuracy but a slower settling time. The QUIET mode
allows more time for DC settling and provides longer
integration time.
CVRange: This is the AC ammeter measurement range of the
CVU. The input values are 0 for autorange, 1µA, 30µA, and1mA ranges.

Connection Compensation. Select Measure Open. After thiscompensation procedure is performed, it can be enabledin this module by selecting OpenCompensate in the Key
Parameters pane.
ShortCompensate: For lower impedance devices, a shortcompensation should be performed. This is especially true forthe two bias tee configuration. First, short the CVH1 and CVL1
terminals. From Tools, select CVU Connection Compensationand then select Measure Short. After this compensation
procedure is performed, short compensation can be enabledin the CvsT module by selecting ShortCompensate in the Key
Parameters pane.

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Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

CVUCableLen: Input the length of the CVU cables. By
default, this is set to 1.5m, the length of the SMA cables thatcome with the 4210-CVU, Keithley P/N CA-447A.

APPLICATION NOTE

Applications for High Voltage
Capacitance Measurements
Even though the user can set up new tests for measuring

MeasISMU: The user inputs the number of the SMU thatmany types of devices, the High Voltage C-V Tests

will measure current in the circuit. The current range is set to(cvu_highv) project comes with tests already configured forlimited autorange to the 100nA range.

four types of devices: zener diodes, MOScaps, capacitors,

SampleCount: Enter the number of capacitancemeasurements from 1 to 10000.

and Schottky diodes. The project tree for the High Voltage
C-V Tests (cvu_highv) project is shown in Figure 3. A
description of the specific tests follows.

Interval: This is the time between readings in seconds.
SMU1Bias, SMU2Bias, SMU3Bias, SMU4Bias: Up to four
SMUs can be used to bias the test circuit. One or two ofthese SMUs is connected through a bias tee(s) to supply
voltage to the DUT for the C-V measurement.
Frequency: Test frequency of CVU which can be set
to 10kHz, 20kHz, 30kHz, 40kHz, 50kHz, 60kHz, 70kHz,
80kHz, 90kHz, 100kHz, 200kHz, 300kHz, 400kHz, 500kHz,
600kHz, 700kHz, 800kHz, 900kHz, 1MHz, 2MHz, 3MHz,
4MHz, 5MHz, 6MHz, 7MHz, 8MHz, 9MHz, and 10MHz. For
higher capacitance values, the test frequency may need
to be lowered through the bias tee to avoid errors due
to resonance.
ACVoltage: The amplitude of the AC voltage outputof the CVU.
Speed: The speed time can be set as: 0 = FAST, 1 =NORMAL, and 2 = QUIET. The FAST mode has the fastest
time but the highest noise. The NORMAL mode is themost common setting, which allows sufficient settling

Figure 3. Project Tree for the High Voltage C-V Tests(cvu_highv) Projecttimes for most measurements. The QUIET mode ensureshigh accuracy but a slower settling time. The QUIET mode

Zener Diode Testingallows more time for DC settling and provides longer

To make high voltage C-V measurements on a zener diode,integration time.

connect the zener diode to the 4200A system as shown in

CVRange: This is the AC ammeter measurement range of the
CVU. The input values are 0 for autorange, 1µA, 30µA, and1mA ranges.

Figure 4. In this configuration, the anode is connected to
the CVH1 terminals of the 4210-CVU and the cathode isconnected to the AC and DC Output terminal of the 4205RBT Remote Bias Tee. This connects the Force and Sense
HI terminals of the SMU (DC bias) and the AC ammeter of the
CVU to the cathode.

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Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

APPLICATION NOTE

to the AC Input of the bias tee. By default, the AC ammeteris internally connected to the CVL1 terminals, and it is best

4210-CVU

that the ammeter be connected to the gate of the device as

H CUR

SMA Tee

H POT
L POT
L CUR

Zener DiodeSMA Cables

FORCE

CVU are connected to the chuck. The DC bias is supplied by
the 4200-SMU, which gets connected to the gate through thebias tee. Connecting the Force HI terminal of the SMU to the

SMA
Tee

gate through the bias tee will ensure the proper polarity of thegate voltage.

AC Input 4205-RBT

4200-SMU
SENSE

shown. The HCUR and HPOT (CVH1) terminals of the 4210-

SENSE

Triax
CablesFORCE

AC & DC
Output4210-CVU

Wafer

H CUR

SMA Tee

H POT
Figure 4. High Voltage C-V Connections for Zener Diode

L POT

The test for testing zener diodes is called hvcv-zener. This

L CUR

Chuck

SMA Cables

test is set up to reverse bias the zener diode from 0 to 180V
in 1V steps. The capacitance as a function of voltage is

AC Input 4205-RBT

4200-SMU

plotted in the graph in the Analyze pane. For displaying theSENSEcapacitance and voltage measurements over a wide range, a

SENSE

Triax
CablesFORCE

log-log or semi-log graph can be generated instead. The C-V

SMA
Tee

FORCE

AC & DC
Output SMA Cable

measurement results of a 1N5388A zener diode are shownin Figure 5.

Figure 6. High Voltage C-V Connections for MOScap Testing

The test for performing high voltage C-V measurements on

1N5388A Zener Diode0 to 180V C-V Sweep

120.0E–12

MOScaps is called hvcv-moscap and is located under the

110.0E–12“moscap” device in the project tree. This test sweeps the

100.0E–12

gate voltage from 10V to –90V in 0.5V steps. The results are

Capacitance (F)90.0E–12graphed as shown in Figure 7.

80.0E–12
70.0E–12
60.0E–12

MOScap C-V Sweep

50.0E–12

90.0E–12

40.0E–12
30.0E–12

10.0E–12

0

30

60

90

120

150

180

Voltage (V)Figure 5. Results of C-V Sweep of Zener Diode

MOScap Testing
The connections for making high voltage capacitance-voltage
measurements on a MOScap are shown in Figure 6. In thisapplication, the LPOT and LCUR (or CVL1) are connected

Capacitance (F)20.0E–12

80.0E–12

70.0E–12

60.0E–12

50.0E–12
–90

–80

–70

–60

–50

–40

–30

–20

–10

0

10

Voltage (V)Figure 7. High Voltage C-V Sweep of MOScap

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Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

APPLICATION NOTE

Table 3. Formulas for hvcv-moscap test
Formula Name,
Units

RS, Ω

Description

Simplified Equations
G
2πfC

RS =

Series resistance calculation

1+

G
2πfC

where C = capacitance in strong accumulation

2

G

AR

Intermediate parameter for calculation of corrected
capacitancea = G – (G2 + (2πfC)2)RSCADJ, F

Corrected capacitance by compensating for series
resistance

CADJ =

COX, F

Oxide Capacitance

Cox = set to the maximum capacitance in accumulation.

CMIN, F

Minimum capacitance

INVCSQR,

Inverse square of capacitance

TOXNM, nm

Calculated thickness of oxide

NDOPING,

Doping density

DEPTHM (w), m

Depletion depth

N90W

Doping density at 90% of maximum depletion depth

DEBYEM (λ), m

Debye length

CFB (CFB), F

Flatband capacitance

VFB (VFB), V

Flatband voltage

PHIB (φB), V

Bulk potential

VTH, V

Threshold voltage

WMS (WMS), V

Work function difference between metal andsemiconductor(G 2 +( 2π fC )2 )C
a 2+(2πfC )2N=
q ε S A2−2
d (1 C 2 )dVwhere 1×E7 = units conversion from cm to nm
εox = permittivity of oxide (F/cm)
A = gate area (cm2)

1×E–2 = units conversion from cm to mwhere N=N at 90% WMAX (or N90W)
1×E–2 = units conversion from cm to m

Once CFB is derived, VFB is interpolated from the closest VGS values.

WM and WS are defined in the constants table in the Formulator

QEFF (QEFF),

Effective oxide charge

BEST_LO

Index from DEPTHM array that is three Debye lengths from the surface

BEST_HI

Index from DEPTHM array that is 95% of maximum depletion length, or twice the screening length in the semiconductor, whichever is larger

NAVG (NAVG),

Average doping

MAXINVSQR

Finds row position of maximum point on

VFBPOS

Finds row position of flatband voltage

NSLOPE

Finds slope of

NSUB,

Calculated substrate doping concentration from slope

8 | WWW.TEK.COM

Calculated between index BEST_HI and BEST_LO
curve

curve

Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

APPLICATION NOTE

Once the C-V measurements are made, various MOScap
100.00E–12

formulas for extracting several parameters including

99.80E–12

threshold voltage, oxide thickness, flatband capacitance,

99.60E–12

doping concentration, etc. These parameters are calculated

99.40E–12

Capacitance (F)parameters can be derived. The hvcv-moscap test includes

in the Formulator and the calculated values appear in the
Sheet. These formulas are listed in Table 3. The specificdetails about these formulas can be found in Keithley

100pF Cap at 200V

99.20E–12
99.00E–12
98.80E–12

Application Note “C-V Characterization of MOS Capacitors

98.60E–12

Using the 4200A-SCS Parameter Analyzer.”

98.40E–12
98.20E–12

In addition to the equations for the derived parameters in

98.00E–12

the Formulator, several constants have been added to the

0

1

2

3

4

5

6

7

Formulator based on the MOScap device being tested.

10

11

12

13

14

15

16

17

19

Figure 8. Capacitance vs. Time Measurements

while an SMU sweeps the test voltage from –200V to +200V.

Description

Default ValueUnits

The results of the C-V sweep of the 100pF capacitor are

AREA

Gate Area of Device

10.8E-3

cm2

shown in Figure 9.

EOX (εox)

Permittivity of Oxide

340.0E-15

F/cm

ES (εs)

Semiconductor Permittivity

1.04E-12

F/cm

NI (Ni)Intrinsic Carrier Concentration

14.5E+09

cm –3

DOPETYPE–1 for 1 for P-type, N-type

1E+00

WM (WM)

Metal Work Function

4.15E+00

V

99.50E–12

WS (WS)

Silicon Electron Affinity

4.05E+00

V

99.30E–12

EBG (EBG)

Semiconductor Energy Gap

1.12E+00

eV

Test Temperature

293E+00

K–200V to 200V Sweep, 100pF Cap
99.90E–12
99.80E–12
99.70E–12
99.60E–12

Capacitor Testing
Two tests exist for testing capacitors: one applies a constant200V bias and the other sweeps the voltage from –200V to
200V. To perform these tests, the capacitor is connected

99.40E–12

Capacitance (F)

TEMP

18

In the 200Vsweep test, the CVU measures the capacitance

Table 4. Constants for hvcv-moscap test
Constant

9

Time (s)Constants Table in the Formulator. These constants are listed
in Table 4. The user will need to adjust these constants in the8

99.20E–12
99.10E–12
99.00E–12
98.90E–12
98.80E–12
98.70E–12
98.60E–12
98.50E–12
98.40E–12
98.30E–12
98.20E–12
98.10E–12
–200

–100

in Figure 1.
High voltage capacitance vs. time measurements can bemade using the 200vbias test, which was created using the

0

100

200

Voltage (V)to the test system using one bias tee as previously shown

Figure 9. ±200 C-V Sweep on 100pF Capacitor

Schottky Diode Testing

CvsT module. This module applies 200V to a 100pF capacitor,

Using two bias tees and two SMUs, C-V measurements canmeasures the capacitance as a function of time, and plots

be made up to 400V. An example of this configuration isthe data in the graph. The results are shown in Figure 8. This

shown in Figure 10. In this setup, the 4210-CVU, two 4205-

module can be used to determine how much settling time to

RBTs, and two 4200-SMUs are connected to a Schottky

use during an actual C-V sweep.

diode. In the 400Vsweep test, capacitance measurements
are made as a 0 to 400V sweep is generated across a

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Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

APPLICATION NOTE

4210-CVUH CUR

SMA Cables

H POT
L POT

SMA Cables

L CUR

4200-SMU 1
SENSE

SMA
Tee

AC Input 4205-RBTAC Input 4205-RBT

SENSE

Triax
Cables

FORCE

SMA
Tee

FORCE

AC & DC
OutputAC & DC
OutputDUT

SMU1 sweeps the voltage
from –200V to +200V.

SENSE
FORCE

4200-SMU 2
Triax
Cables

SENSE
FORCE

SMU2 outputs a
constant –200V.

Figure 10. High Voltage C-V Connections for Schottky Diode Test

Schottky diode. To generate the 0 to 400V sweep, SMU1

The two modules in the hivcvulib library include an adjustablesweeps from –200V to 200V while SMU2 outputs a constant

Speed parameter. The Speed parameter can be set as:–200V bias. This results in a high voltage C-V sweep as

0 = FAST, 1 = NORMAL, and 2 = QUIET. The FAST modeshown in the graph in Figure 11.

has the fastest time but the highest noise. The NORMAL
mode is the most common setting, which allows sufficient
settling times for most measurements. The QUIET mode

0 to 400V Sweep of SiC Schottky Diode260.0E–12

ensures high accuracy but a slower settling time. The QUIET

240.0E–12

mode allows more time for DC settling and provides longer

220.0E–12

Capacitance (F)200.0E–12

integration time.

180.0E–12
160.0E–12

Choosing an appropriate PreSoak Time and SweepDelay

140.0E–12
120.0E–12

Time is important for many applications. The condition of

100.0E–12

a device when all internal capacitances are fully charged

80.0E–12

after an applied step voltage is referred to as “equilibrium.”

60.0E–12

If capacitance measurements are made before a device

40.0E–12
20.0E–12

0

30

60

90

120

150

180

Voltage (V)is in equilibrium, inaccurate results may be produced. To
choose the delay times for the SweepV user module, makea measurement of capacitance vs. time in the CvsT user

Figure 11. Results of High Voltage C-V Sweep of Schottky Diode

Optimizing Measurements
When making high voltage C-V measurements, as withmaking C-V measurements in general, various techniques
can be used to optimize measurement accuracy. These
techniques include choosing the proper speed modes,

module. Observe the settling time on the graph. Use this timeas the PresoakTime for the PreSoakV or the SweepDelay time
applied to each step in the sweep in the SweepV module.
When making C-V measurements, it is important to takesteps to reduce the effects of stray capacitance, which
include offset compensation and proper connections.

allowing sufficient settling time, and taking steps to reduce

To correct for offsets, use Open and Short Compensation.

the effects of stray capacitance.

Open Compensation corrects for large impedance, small
capacitance offsets. Short Compensation corrects for

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Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

low impedance, high capacitance offsets. Open andShort Compensation are explained in greater detail in the4200A-SCS Reference Manual.
To avoid noisy measurements and stray capacitance, theAC ammeter terminal (LCUR) should always be connectedto the terminal of the device that has the least amount of

APPLICATION NOTE

• Where possible, use automated handlers so operators do
not require access to the inside of the test fixture or havea need to open guards.
• Provide proper training to all users of the system so they
understand all potential hazards and know how to protect
themselves from injury.

capacitance to ground. When measuring MOScaps, always

It is the responsibility of the test system designers,

connect the CVL1 terminals (LCUR and LPOT) to the gate andintegrators, and installers to make sure operator andthe CVH1 terminals (HCUR and HPOT) to the chuck.

maintenance personnel protection is in place and effective.

Because the bias tee unavoidably adds some external

Conclusion

parasitics to the measurement circuit, care must be
taken when making measurements especially at higher

Using the 4200-CVU-PWR C-V Power Package for thecapacitances using higher test frequencies (>1MHz). If

4200A-SCS allows making C-V measurements with a DC

measurement errors are suspected, make C-V measurements

voltage bias of up to ±200V or 400V differential and a current

without the bias tee, and then make measurements throughoutput of up to 300mA. To achieve the higher test voltage

the bias tee with the same test conditions (frequency, voltage,

and current, this package couples the AC and DC signals

speed, interval time, etc.). The measurements without thefrom the 4210-CVU and 4200-SMU (or 4210-SMU) using

bias tee will be limited to ±30V. If there are discrepancies,

the 4205-RBT Remote Bias Tees. Software that allows

try lowering the test frequency, if possible, and use the Quiet

making either high voltage C-V sweeps or capacitancespeed mode. Increasing the settling time may ensure themeasurements at a constant DC voltage is included with thedevice has reached equilibrium.

4200A. Example tests are included for a zener diode, MOS
capacitor, capacitor, and Schottky diode. These tests can be

Test System Safety

easily modified to measure other devices or new tests can be

Many electrical test systems or instruments are capablemeasurements in general, high voltage C-V measurementsof measuring or sourcing hazardous voltage and power
levels. It is also possible, under single fault conditions (e.g.,a programming error or an instrument failure), to output

created by opening a new test in another project. Like C-V
require using appropriate measurement techniques andconnections to ensure optimal results.

hazardous levels even when the system indicates no hazard
is present. These high voltage and power levels make itessential to protect operators from any of these hazards at all
times. Protection methods include:• Design test fixtures to prevent operator contact with any
hazardous circuit.
• Make sure the device under test is fully enclosed toprotect the operator from any flying debris.
• Double insulate all electrical connections that an operator
could touch. Double insulation ensures the operator is still
protected, even if one insulation layer fails.
• Use high reliability, fail-safe interlock switches todisconnect power sources when a test fixture cover isopened.

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Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

APPLICATION NOTE

Appendix

References

Ordering Information

1.

4200A-SCS Reference Manual

4200-CVU-PWR C-V Power Package

2.

Keithley Application Note, “C-V Characterization of MOS
Capacitors Using the 4200A-SCS Parameter Analyzer”

Includes:2 ea. 4205-RBT
2 ea. SMA F-M-F Tee adaptors CS-1391
2 ea. Male SMA to Female BNC adapter CS-1252
2 ea. SMA to SSMC Y-Cables 4200-PRB-C

CVU Power Package Typical Performance
Parameters
Measurement Parameters: Cp-Gp, DCV, timestamp
Capacitance Range: from fF to nF
Measurement Terminals: two-wire SMA with BNC adapters(CVU), Triax (SMU)
Test Signal: 100kHz to 10MHz, 10mV to 100mV AC
DC voltage source: ±200V with 5mV resolution (400V
differential)
DC current: 100mA (MPSMU) or 300mA (HPSMU) maximum
Typical Cp Accuracy @ 1MHz: 1.0%
DC current sensitivity: 10nA/V
Number of SMU bias terminals supported: 4

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Using the 4200-CVU-PWR C-V Power Package to Make High Voltage and High
Current C-V Measurements with the 4200A-SCS Parameter Analyzer

APPLICATION NOTE

Contact Information:
Australia* 1 800 709 465
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