The effects of aging on MOS irradiation and annealing response

We find that, after approximately 17 years of room-temperature storage, the irradiation and annealing responses of poly-Si-gate nMOS transistors can change significantly. For devices with 32 nm gate oxides that were stored in a nonhermetic environment, the magnitude of the threshold-voltage rebound...

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Bibliographic Details
Published in:IEEE transactions on nuclear science 2005-12, Vol.52 (6), p.2642-2648
Main Authors: Rodgers, M.P., Fleetwood, D.M., Schrimpf, R.D., Batyrev, I.G., Wang, S., Pantelides, S.T.
Format: Article
Language:English
Subjects:
Activation energy
Aging
Aging effects
Amorphous materials
Annealing
Construction
Degradation
Density functional theory
Devices
hardness assurance
interface traps
Interstitials
Irradiation
Metal oxide semiconductors
MOS devices
MOSFETs
Oxides
Packaging
Quantum mechanics
semiconductor device radiation effects
Studies
Testing
Water
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Summary:We find that, after approximately 17 years of room-temperature storage, the irradiation and annealing responses of poly-Si-gate nMOS transistors can change significantly. For devices with 32 nm gate oxides that were stored in a nonhermetic environment, the magnitude of the threshold-voltage rebound during postirradiation annealing is much larger now than in previous tests on devices from the same wafer and packaging lot in 1988. These changes in threshold-voltage shifts during storage are primarily due to a more than 50% increase in interface-trap generation during irradiation and annealing. When these parts are baked before irradiation, the aging-related increase in threshold-voltage shift is reduced significantly. Water molecules absorbed in the device are likely candidates for causing aging-related degradation in a nonhermetic environment, so we investigated the properties of H/sub 2/O in amorphous SiO/sub 2/ using first-principles quantum-mechanical calculations based on density functional theory. We find a complex with energy that is 0.3 eV smaller than interstitial H/sub 2/O, with an activation energy of formation of
ISSN:0018-9499
1558-1578
DOI:10.1109/TNS.2005.861079