Keithley 4200-SCS Reference Manual page 1653

Model 4200-SCS Reference Manual
I_init
hold_time
v_start
v_step
t_step
measure_delay
I_crit
I_box
I_max
exit_curr_mult
exit_slope_mult
q_max
t_max
v_max
area
exit_mode
4200-901-01 Rev. S / May 2017
(double) Oxide breakdown failure current when biased at v_use. Typical
value is 10 uA/cm^2 and may change depending on oxide area. For
maximum sensitivity, the specified value should be well above the worse
case oxide current of a "good" oxide and well above the noise level of the
measurement system. Higher values must be specified for ultra-thin oxide
because of direct tunneling effects (Ref. JESD35-A).
(init) Time in ms to hold the first stress (v_start).
(double) Starting voltage (V) for voltage ramp. Typical value is v_use (Ref.
JESD35-A).
(double) Voltage (V) ramp step height. This value has a maximum value
of 0.1 MV/cm. For example, the maximum value can be calculated using
Tox*0.1 MV/cm, where Tox is in unit of centimeters. This is 0.1 V for a
10nm oxide (Ref. JESD35-A).
(int) Voltage ramp step time in ms. This is used to determine the voltage
ramp rate. This time should be less or equal than 100 ms. Typically
40 to 100 ms.
(int) Time delay in ms for measurement after each voltage stress step.
This delay should be less than t_step (ms).
(double) At least 10 times the test system current measurement noise
floor. This oxide current (A) is the minimum value used in determining the
change of slope breakdown criteria (Ref. JESD35-A).
(double) An optional measured current level for which a stress voltage is
recorded.
This value provides an additional point on the current-voltage curve. A
typical value is 1uA (Ref. JESD35-A).
(double) Oxide breakdown criteria. I_bd is obtained from I-V curves and is
the oxide current at the step just prior to breakdown (Ref. JESD35-A).
(double) Change of current failure criteria. This is the ratio of measured
current over previous current level, which, if exceeded, will result in failure
(2.5 to 5, recommended value: 10-100).
(double) Change of slope failure criteria. This is the factor of change in FN
slope, which, if exceeded, will result in failure (2.5 to 5; recommended
value: 3).
(double) Maximum accumulated oxide charge per oxide area. Used to
terminate a test where breakdown occurs but was not detected during the
test (C/cm^2) (Ref. JESD35-A).
(double) Maximum stress time allowed in seconds. Reaching this limit will
result in test to finish (s).
(double) The maximum voltage limit for the voltage ramp. This limit is
specified at 30MV/cm for oxides less than 20nm thick and 15MV/cm for
thicker oxides. For example, v_max can be estimated from Tox*30Mv/cm
where Tox is in centimeters. 35 V for a 10.0nm Oxide (Ref. JESD35-A).
(double) Area of oxide structure (cm^2).
(int) Failure criteria mode:
0 Specifies that oxide failure is determined by a measured current that
exceeds the user specified failure current (fail_current).
1 This mode uses two criteria to determine oxide failure. The first
criteria is the specified failure current (fail_current). The second
criteria is a slope of current measurement that is a factor
(exit_slope_mult) times the previous measured value. See JEDEC
document JESD35-A and Addenda (JESD35-1 and JESD35-2).
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Appendix M: WLR Testing
M-11