Keithley 4200A-SCS - Page 1362

Model 4200A
-SCS Parameter Analyzer Reference Manual Appendix L: Wafer-
level reliability testing
4200A-901-01 Rev. C / February 2017 L-13
Output variables
V_stress
Voltage stress array
I_stress
Measured current array
T_stress
Time stamp array indicating when current is measured
q_stress
Accumulated charge array
I_use_pre
Measured oxide current at v_use, before starting the ramp (Ref. JESD35-A)
I_use_post
Measured oxide current at v_use, after the ramp finished (Ref. JESD35-A)
Q_bd
Charge-to-breakdown; cumulative charge passing through the oxide before
breakdown (C) (Ref. JESD35-A)
q_bd
Charge-to-breakdown density (C/cm
2
) (Ref. JESD35-A)
v_bd
Applied voltage at the step just before oxide breakdown (Ref. JESD35-A)
I_bd
Measured current at v_bd, just before oxide breakdown
t_bd
Time stamp when measuring I_bd
v_crit
Applied voltage at the step when the oxide current exceeds I_crit
(Ref. JESD35-A)
v_box
Applied voltage at the step when the oxide current exceeds I_box (Ref. JESD35-A)
failure_mode
•
Initial test failure
• Catastrophic failure (initial test pass, ramp test fail, post test fail)
• Masked Catastrophic (initial test pass, ramp test pass, post test fail)
• Non-Catastrophic (initial test pass, ramp test fail, post test pass)
• Others (initial test pass, ramp test pass, post test pass)
test_status
See Details
Details
Performs a charge-to-breakdown test using the QBD V-ramp test algorithm described in JESD35-A
"Procedure for Wafer-Level Testing of Thin Dielectrics," April 2011. This algorithm forces a linear
voltage ramp until the oxide layer breaks down. This algorithm is capable of a maximum voltage of
±200 V. The flow diagram for the V-ramp test is shown in V-Ramp Flow Diagram (on page L-15
).
Notes on input variables
hi_pin and lo_pinX: If there is no switching matrix in the system, enter either 0 or −1 for hi_pin
and lo_pinX to bypass switch.
I_init: The typical value of I_init is 10 µA/cm
2
and may change depending on oxide area. For
maximum sensitivity, the specified value should be well above the worst 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).
v_step: As an example, the maximum value of v_step can be calculated using Tox*0.1 MV/cm,
where Tox is in unit of centimeters. This is 0.1 V for a 10 nm oxide (Ref. JESD35-A).
v_max: As an example, v_max can be estimated from T
ox
*30 MV/cm, where T
ox
is in centimeters.
This is 35 V for a 10.0 nm Oxide (Ref. JESD35-A).