AT89C51ED2 Datasheet, PDF (12/24 Pages) ATMEL Corporation – 8-bit Flash Microcontroller

AT89C51RD2 / AT89C51ED2 QualPack
4.3.3 Time Dependent Dielectric Breakdown
Purpose:
To evaluate the AT56800 thin gate oxide TDDB performance as follows:
a) To determine the activation energy of gate oxide failures on STI active edge capacitors
b) To determine the field acceleration factor for intrinsic gate oxide failures
c) To determine the sigma the lognormal standard deviation of the time to breakdown distribution of the
intrinsic gate oxide
Test Parameters:
Lot
Min thickness:
Max thickness:
Capacitor size:
9G3470 (wafers 4, 5, 18)
72.9A
74.7A
6.267 um²
The stress conditions used are shown below:
Temperature/Field
9.5MV/cm
225C
N=5
200C
N=5
175C
N=5
10.0MV/cm
N=5
N=5
N=5
10.5MV/cm
N=5
N=5
N=6
Accumulated total stress time: 132 hours / 46 capacitors
Calculation Parameters:
Failure Criteria:
Temp/Voltage use:
Oxide thickness:
0.01% failures
105°C / 3.3V
63A (target –10%)
Lifetime Prediction:
The equation used to describe the breakdown of gate oxides is:
Tbd(i) = exp(SIGMA*Z(i) + GAMMA*Eox +Ea/kT + T0)
Where
Tbd(i) is the time to breakdown of the i^th capacitor,
SIGMA is the lognormal standard deviation of the breakdown distribution,
Z(i) is the Z-score of the i^th capacitor (essentially the difference between its breakdown time and the mean
measured in standard deviations),
GAMMA is the Field acceleration constant,
Eox is the oxide field,
Ea is the activation energy of this failure mechanism,
K is Boltzmann’s constant,
T is the Kelvin Temperature, and
T0 is a fitting constant.
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Rev. 0 – 2003 July