Damage-to-dose ratio after low energy silicon ion implantation into crystalline silicon (original) (raw)
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Damage to Crystalline Silicon Following Implantation by Low Energy Silicon Ions
MRS Proceedings, 1992
A new approach to investigate low energy defect formation and annealing in a crystal is developed, based on experimental observations of the total number of interstitials. The model is applied to damage in crystalline silicon caused by low energy implantation of Siatoms during 40eV implants at 300°Kand 685*K. The model has two versions, analytical and computational, and includes two kinds of diffusing species, self-interstitials and vacancies, their interaction, surface motion of the growing crystal, and a constant source of defects. The source was calculated using a modified TRIM code (TRIMCSR). The focal point of the analysis is the number of interstitials per ion dose surviving at the end of the deposition time (damage to dose ratio or DDR),which is found to be an informative quantity and can be calculated for more sophisticated models including precipitation.
Applied Physics Letters, 1996
A new atomistic approach to Si device process simulation is presented. It is based on a Monte Carlo diffusion code coupled to a binary collision program. Besides diffusion, the simulation includes recombination of vacancies and interstitials, clustering and re-emission from the clusters, and trapping of interstitials. We discuss the simulation of a typical room-temperature implant at 40 keV, 5ϫ10 13 cm Ϫ2 Si into ͑001͒Si, followed by a high temperature ͑815°C͒ anneal. The damage evolves into an excess of interstitials in the form of extended defects and with a total number close to the implanted dose. This result explains the success of the ''ϩ1'' model, used to simulate transient diffusion of dopants after ion implantation. It is also in agreement with recent transmission electron microscopy observations of the number of interstitials stored in ͑311͒ defects.
A detailed physical model for ion implant induced damage in silicon
IEEE Transactions on Electron Devices, 1998
A unified physically based ion implantation damage model has been developed which successfully predicts both the impurity profiles and the damage profiles for a wide range of implant conditions for arsenic, phosphorus, BF 2 , and boron implants into single-crystal silicon. In addition, the amorphous layer thicknesses predicted by this new damage model are also in excellent agreement with experimental measurements. This damage model is based on the physics of point defects in silicon, and explicitly simulates the defect production, diffusion, and their interactions which include interstitial-vacancy recombination, clustering of same type of defects, defect-impurity complex formation, emission of mobile defects from clusters, and surface effects for the first time. New computationally efficient algorithms have been developed to overcome the barrier of the excessive computational requirements. In addition, the new model has been incorporated in the UT-MARLOWE ion implantation simulator, and has been developed primarily for use in engineering workstations. This damage model is the most physical model in the literature to date within the framework of the binary collision approximation (BCA), and provides the required, accurate asimplanted impurity profiles and damage profiles for transient enhanced diffusion (TED) simulation.
Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms, 1996
We report a simple and efficient algorithm to calculate the growth of damage in Si within the framework of a recently developed Monte Carlo code for the simulation of ion implantation in crystals. We let the defects created by the incoming ions interact, during the simulation, with the damage previously accumulated. We assume this dynamical interaction to depend both on defect generation density and concentration of pre-existing damage. Preliminary comparison of calculations with experimental data in the case of Si samples implanted with 700 keV N+ ions shows that this scheme can well reproduce the observed non-linearities in the growth behavior.
Onset of implant-related recombination in self-ion implanted and annealed crystalline silicon
2004
The impact of residual recombination centers after low-energy self-implantation of crystalline silicon wafers and annealing at 900°C has been determined by bulk carrier lifetime measurements as a function of implant dose. Doses below 10 13 cm −2 resulted in no measurable increase in recombination, while higher doses caused a linear increase in the recombination center density. This threshold value corresponds to the known critical dose required for the formation of relatively stable dislocation loops during high temperature annealing. Deep level transient spectroscopy revealed a decrease in the vacancy-related defect concentration in the high-dose samples, which we interpret as reflecting an increase in the silicon interstitial concentration. This suggests that silicon interstitials, arising from the slowly dissolving dislocation loops, may be responsible for the increased recombination deep within the samples.
Damage evolution in low-energy ion implanted silicon
Physical Review B, 2007
The annealing of damage generated by low-energy ion implantation in polycrystalline silicon ͑poly-Si͒ and amorphous silicon ͑a-Si͒ is compared. The rate of heat release between implantation temperature and 350-500°C for Si implanted in both materials and for different ions implanted in poly-Si shows a very similar shape, namely, a featureless signal that is characteristic of a series of processes continuously distributed in terms of activation energy. Nanocalorimetry signals differ only by their amplitude, a smaller amount of heat being released after light ion implantation compared to heavier ones for the same nominal number of displaced atoms. This shows the importance of dynamic annealing of the damage generated by light ions. A smaller amount of heat is released by implanted poly-Si compared to a-Si, underlining the effect of the surrounding crystal on the dynamic annealing and the relaxation of the defects. Damage accumulation after 30-keV Si implantation is also characterized by Raman scattering and reflectometry, featuring a similar trend in a-Si, poly-Si, and monocrystalline silicon ͑c-Si͒ with a saturation around 4 Si/ nm 2. Considering these results together with other recent experiments in c-Si and molecular dynamic simulations, it is concluded that the damage generated by low-energy ion implantation that survives dynamic annealing is structurally very similar if not identical in both crystalline and amorphous silicon, giving rise to the same kind of processes during a thermal anneal. However, the damage peak obtained by channeling saturates only above 10 Si/ nm 2. This suggests that between 4 and 10 Si/ nm 2 , further damage occurs by structural transformation without the addition of more stored energy.
Dependence of transient enhanced diffusion on defect depth position in ion implanted silicon
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1989
Transient enhanced diffusion of phosphorus in silicon has been investigated for implants below and above the threshold for complete amorphization. In the first case, a strong enhanced diffusion, proportional to the amount of damage produced, has been observed. The extent of the phenomenon is practically independent of the damage depth position. On the contrary, the formation of extended defects at
Damage accumulation in Si during high-dose self-ion implantation
Journal of Applied Physics, 2004
Accumulation and annealing of damage in Si implanted with self-ions to high doses were investigated using a combination of grazing incidence diffuse x-ray scattering, high-resolution x-ray diffraction scans, and transmission electron microscopy. During implantation at 100°C, small vacancy and interstitial clusters formed at low doses, but their concentrations saturated after a dose of Ϸ3 ϫ 10 14 cm −2. The concentration of Frenkel defects at this stage of the implantation was Ϸ1 ϫ 10 −3. At doses above 1 ϫ 10 15 cm −2 , the concentration of implanted interstitial atoms began to exceed the Frenkel pair concentration, causing the interstitial clusters to grow, and by Ϸ3 ϫ 10 15 cm −2 , these clusters formed dislocation loops. Kinematical analysis of the rocking curves illustrated that at doses above 1 ϫ 10 15 cm −2 the "plus one" model was well obeyed, with one interstitial atom being added to the dislocation loops for every implanted Si atom. Measurements of Huang scattering during isochronal annealing showed that annealing was substantial below 700°C for the specimens irradiated to lower doses, but that little annealing occurred in the other samples owing to the large imbalance between interstitial and vacancy defects. Between 700 and 900°C a large increase in the size of the interstitial clusters was observed, particularly in the low-dose samples. Above 900°C, the interstitial clusters annealed.
Comprehensive model of damage accumulation in silicon
Journal of Applied Physics, 2008
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.
Atomistic modeling of ion implantation technologies in silicon
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2015
Requirements for the manufacturing of electronic devices at the nanometric scale are becoming more and more demanding on each new technology node, driving the need for the fabrication of ultra-shallow junctions and finFET structures. Main implantation strategies, cluster and cold implants, are aimed to reduce the amount of end-of-range defects through substrate amorphization. During finFET doping the device body gets amorphized, and its regrowth is more problematic than in the case of conventional planar devices. Consequently, there is a renewed interest on the modeling of amorphization and recrystallization in the front-end processing of Si. We present multi-scale simulation schemes to model amorphization and recrystallization in Si from an atomistic perspective. Models are able to correctly predict damage formation, accumulation and regrowth, both in the ballistic and thermal-spike regimes, in very good agreement with conventional molecular dynamics techniques but at a much lower computational cost.