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Title: Radiation Effects in MOS Oxides.


Abstract not provided.

Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
Report Number(s):
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: Proposed for presentation at the 9th European Conf. Radiation & Its Effects on Components and Systems held September 10-14, 2007 in Deauville, France.
Country of Publication:
United States

Citation Formats

Schwank, James R. Radiation Effects in MOS Oxides.. United States: N. p., 2007. Web.
Schwank, James R. Radiation Effects in MOS Oxides.. United States.
Schwank, James R. Tue . "Radiation Effects in MOS Oxides.". United States. doi:.
title = {Radiation Effects in MOS Oxides.},
author = {Schwank, James R.},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}

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  • Changes in interface trap density D[sub it] have been determined in MOSFETs as a function of time during hydrogen annealing at 295K. Large increases in D[sub it] are observed during H[sub 2] annealing in MOSFETs previously stressed by either [sup 60]Co irradiation or Fowler-Nordheim electron injection. The annealing behavior is very similar for both types of stress, which suggests that the D[sub it] creation mechanism involves similar chemistry for hydrogen reactions. Studies of the time dependence of D[sub it] creation as a function of MOSFET gate length show that the time dependence is limited primarily by lateral diffusion of molecularmore » hydrogen (H[sub 2]) through the gate oxide. An activation energy of 0.57 eV, which is consistent with H[sub 2] diffusion, is obtained from the temperature dependence.« less
  • The response of MOS capacitors to low- and medium-energy x-ray irradiation is investigated as a function of gate material (TaSi or Al), oxide thickness, and electric field. Measured device response is compared with predictions based on discrete ordinates and Monte Carlo code simulations of dose enhancement effects, coupled with recent estimates of electron-hole recombination in MOS oxides. In comparisons of 10-keV x-ray and Co-60 irradiations of Al-gate MOS capacitors at an oxide electric field of 1 MV/cm, it is found that predictions and experiments agree to within better than 20 percent for oxide thicknesses ranging from 35 to 1060 nm.more » For capacitors having TaSi/Al gates, predictions and experiments agree to within better than 30 percent at 1 MV/cm, with the largest differences occurring for 35-nm gate oxides. At other electric fields, the disagreement between experiment and prediction increases significantly for both Al- and TaSi/Al-gate capacitors, and can be greater than a factor of 2 at applied electric fields below 0.1 MV/cm. For medium energy (-- 100 keV average photon energy) x-ray irradiations, the enhanced device response exhibits a much stronger dependence on endpoint bremsstrahlung energy than expected from TIGERP or CEPXS/ONETRAN simulations. Implications for hardness assurance testing are discussed.« less
  • By introducing small amounts of fluorine into the gate oxide, the authors have been able to significantly alter the radiation response of Metal/SiO/sub 2//Si (MOS) capacitors, and their subsequent time dependent behavior. Experimentally they observed that compared with their control capacitors, which have no fluorine introduced into the oxide, the fluorinated samples exhibit the following major differences: (1) the densities of radiation-induced oxide charge and interface traps are drastically reduced, (2) the gate-size dependence of the radiation-induced interface traps is greatly suppressed, and (3) the overall density of the radiation-induced interface traps continues to decrease with time for many hoursmore » after irradiation before a turn-around trend is observed. Possible mechanisms involving the roles that fluorine may play in relieving the oxide strain near the SiO/sub 2//Si interface and in the post-irradiation defect-reaction chemistry are discussed.« less
  • Radiation effects on p{sup +} poly gate MOS structures with thin (25 nm {minus} 10 nm) oxides are investigated and compared with those on n {plus} poly gate MOS structures by using a high frequency C {minus} V technique. It is found that the characteristics of the oxide charge buildup and the interface state generation are different between n{sup +} and p{sup +} poly gate. The results indicate that these differences are attributed to boron atoms penetrating to the gate oxide from polysilicon gate. Based on these observations, the authors propose a model for the role of boron atoms inmore » the oxide.« less
  • The field and temperature dependence of the interface-state density as a function of time following pulsed e-beam irradiation, and the dose dependence of the interface-state density following steady state /sup 60/Co irradiation were examined in MOS capacitors with both hardened dry and wet (pyrogenic) gate oxides. From the results of the pulsed e-beam experiment, it is shown that in the wet oxide the electric field affects the time scale for the buildup of interface states as well as the final or saturation value of interface states at late times (approximately 10/sup 5/ s), but that in the dry oxide theremore » is no marked field dependence. For the wet oxide, temperature affects only the time scale for the buildup of interface states. From total-dose /sup 60/Co measurements, a power law dependence is reported on dose, D/sup 0/./sup 65/, for both wet and dry oxide capacitors. The buildup of interface states in the wet-oxide capacitors is considerably larger than in the dry.« less