Damage Accumulation In Silicon Research Articles

Hydrogen enhanced mechanical fatigue in single crystal silicon

Silicon fatigue lifetime was examined in four different environments. Fatigue failure occurs in the range of 103–105 cycles under the stress amplitude level of around 90% to the static fracture strength under monotonic loading, both in lab air with relative humidity (RH) 35–40% and hydrogen with RH 5%. In contrast, no specimen fractures with the same stress level up to more than 107 cycles in nitrogen and oxygen with RH 5%. These facts suggest that hydrogen, which could also be supplied from water adsorbed on the surface, had a significant impact on the fatigue damage accumulation in silicon.

Molecular dynamics simulation of annealing of post-ballistic cascade remnants in silicon

A molecular dynamics simulation of the long-term annealing of collision cascade remnants in silicon is reported. The aim of the study is to determine how many point defects in freely-migrating and clustered form remain in the cascade region after the complete recrystallization of cascade-generated amorphous zones and the recombination of close-lying mobile defects. Representative damage patterns created by self-ion recoils in the energy range of 0.5–5keV are used as the starting configurations. The simulation shows a strong difference in the clusterization level of vacancies and interstitials after the long term annealing, suggesting explanation for some not yet clearly understood features of radiation damage accumulation in silicon. An overall low ultimate level of damage generation in cascades (∼5 surviving interstitial–vacancy pairs per keV of initial recoil energy) is predicted.

Comprehensive model of damage accumulation in silicon

Ion implantation induced damage accumulation is crucial to the simulation of silicon processing. We present a physically based damage accumulation model, implemented in a nonlattice atomistic kinetic Monte Carlo simulator, that can simulate a diverse range of interesting experimental observations. The model is able to reproduce the ion-mass dependent silicon amorphous-crystalline transition temperature of a range of ions from C to Xe, the amorphous layer thickness for a range of amorphizing implants, the superlinear increase in damage accumulation with dose, and the two-layered damage distribution observed along the path of a high-energy ion. In addition, this model is able to distinguish between dynamic annealing and post-cryogenic implantation annealing, whereby dynamic annealing is more effective in removing damage than post-cryogenic implantation annealing at the same temperature.

Ion-channeling and Raman scattering study of damage accumulation in silicon

Damage was introduced into Si(100) using 245 keV Si+ ions implanted to a wide range of doses with implant temperatures of −195, 25 or 100 °C. The accumulation of this damage was monitored with Rutherford backscattering and ion channeling (RBS-C) and by following the intensity and lineshape variation of the first-order (1-O) Raman peak of silicon. For all implant temperatures the RBS-C data showed the expected trend with dose. For −195 °C and room temperature implants, the decrease in intensity of the 1-O Raman peak shows a similar trend to the RBS-C data, but in each case the threshold dose is about a decade lower than its RBS-C counterpart. On implantation at 100 °C the sensitivity of the Raman spectra to low damage concentrations is more dramatic and decreases continuously over the full dose range, from 5×1012 to 2×1016 Si/cm2, examined in this study. This suggests that the intensity of the 1-O Raman peak is particularly sensitive to the types of defect structures that are stable in silicon during irradiation at elevated temperatures. The phonon confinement model is discussed in light of these results.

Coupled Kinetic Monte Carlo and Molecular Dynamics Simulations of Implant Damage Accumulation in Silicon

ABSTRACTDamage formation during ion implantation is a complex process that cannot accurately be modeled by binary collision simulations alone. Molecular dynamics (MD) simulations are suited to describe the quenching of collision cascades, while thermally activated processes may be treated with the kinetic Monte Carlo (kMC) method.MD and kMC simulations have widely but separately been used to investigate damage accumulation and annealing in silicon. Simulation of ion implantation at room temperature, however, requires both methods to be coupled. In this paper we describe for the first time a scheme of the coupling between MD and lattice kMC for damage accumulation. Using this scheme we study the dynamic annealing behavior of implantation damage for heavy and light ions.

Charge State Defect Engineering of Silicon During Ion Implantation

AbstractThe effects of in situ interventions which alter defect interactions during implantation, and thereby affect the final damage state, have been investigated. Specifically, we examined the effects of internal electric fields and charge carrier injection on damage accumulation in silicon. In the first part of this work, we implanted H or He ions into diode structures which were either reverse or forward biased during implantation. In the second part, we implanted B or Si ions into plain silicon wafers whilst illuminating them with UV light. In each case, the overall effect is one of damage reduction. Both the electric field and charge carrier injection effects may be understood as resulting from changes in defect interactions caused in part by changes to the charge state of defects formed during implantation.

Dose Rate Effects During Damage Accumulation in Silicon

AbstractWe combine molecular dynamics and Monte Carlo simulations to study damage accumulation and dose rate effects during irradiation of Silicon. We obtain the initial stage of the damage produced by heavy and light ions using classical molecular dynamics simulations. While heavy ions like As or Pt induce amorphization by single ion impact, light ions like B only produce point defects or small clusters of defects. The amorphous pockets generated by heavy ions are stable below room temperature and recrystallize at temperatures below the threshold for recrystallization of a planar amorphous-crystalline interface. The damage accumulation during light ion irradiation is simulated using a Monte Carlo model for defect diffusion. In this approach, we study the damage in the lattice as a function of dose and dose rate. A strong reduction in the total number of defects left in the lattice is observed for lower dose rates.

Dose Rate Effects During Damage Accumulation in Silicon

AbstractWe combine molecular dynamics and Monte Carlo simulations to study damage accumulation and dose rate effects during irradiation of Silicon. We obtain the initial stage of the damage produced by heavy and light ions using classical molecular dynamics simulations. While heavy ions like As or Pt induce amorphization by single ion impact, light ions like B only produce point defects or small clusters of defects. The amorphous pockets generated by heavy ions are stable below room temperature and recrystallize at temperatures below the threshold for recrystallization of a planar amorphous-crystalline interface. The damage accumulation during light ion irradiation is simulated using a Monte Carlo model for defect diffusion. In this approach, we study the damage in the lattice as a function of dose and dose rate. A strong reduction in the total number of defects left in the lattice is observed for lower dose rates.

Charge State Defect Engineering of Silicon During Ion Implantation

AbstractThe effects of in situ interventions which alter defect interactions during implantation, and thereby affect the final damage state, have been investigated. Specifically, we examined the effects of internal electric fields and charge carrier injection on damage accumulation in silicon. In the first part of this work, we implanted H or He ions into diode structures which were either reverse or forward biased during implantation. In the second part, we implanted B or Si ions into plain silicon wafers whilst illuminating them with UV light. In each case, the overall effect is one of damage reduction. Both the electric field and charge carrier injection effects may be understood as resulting from changes in defect interactions caused in part by changes to the charge state of defects formed during implantation.

Flux Dependence of Damage Accumulation in Silicon during Ion Bombardment

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