Model 4200A-SCS Parameter Analyzer Reference Manual
Section 4: Multi-frequency capacitance-voltage unit
4200A-901-01 Rev. C / February 2017
4-69
The equilibrium inversion depth (w
F
) is calculated as:
Where:
•
w
F
= equilibrium inversion depth (cm)
•
ε
S
= permittivity of the substrate material (F/cm)
•
A = gate area (cm
2
)
•
C
MIN =
Minimum oxide capacitance (F)*
•
C
OX
= Oxide capacitance (F)*
*
C
MIN
and
C
OX
are calculated (with the results placed in the Analyze sheet) when the C-V test is run.
The values for these parameters must be input into the Formulator for the
gni-w-wf
test.
The depletion depth is calculated from the following equation:
Where:
•
w
= depletion depth (cm)
•
w
F
= equilibrium inversion depth (cm)
•
ε
S
= permittivity of the substrate material (F/cm)
•
A = gate area (cm
2
)
•
C
ti
= i(th) value of measured C-t capacitance (F)
•
C
OX
= oxide capacitance (F)*
*
C
OX
is calculated (with the result placed in the Analyze sheet) when the C-V test is run. The value for
this parameter must be input into the Formulator for the
gni-w-wf
test.
One of the perplexing parts of the Zerbst method is to determine how to space the capacitance
measurements. Capacitance measurement spacing almost entirely depends on how fast minority
carriers can be generated. The interval time for the measurements can be adjusted depending on the
device.
gni-w-wf test procedure
1. Run the C-V test.
2. Get the calculation results for the C
OX
,
C
MIN
and
N
AVG
formulas from the Analyze sheet.
3. Input the values for C
OX
,
C
MIN
, and
N
AVG
into the Formulator for the
gni-w-wf
test (for example,
C
OX
= 145E-12).
4. Run the
gni-w-wf
test to generate the Zerbst plot.
If the value for the
N
AVG
in the Formulator is known, it can be used instead of the one derived from
the C-V test.
