Characterisation of the Subthreshold Damage in MeV Ion Implanted p Si (original) (raw)
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Defect evolution in MeV ion-implanted silicon
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms - NUCL INSTRUM METH PHYS RES B, 1996
Lightly doped silicon samples of both n- and p-type have been implanted with low doses of H, B and Si ions using energies between 1 and 6 MeV. The resulting electrically active point defects were characterized by deep level transient spectroscopy (DLTS) and several of these defects involve oxygen and/or carbon, two major impurities in as-grown crystalline silicon. Both interstitial- and vacancy-type defects are observed; in particular, interstitial carbon is found to migrate at room temperature with a diffusion constant of ∼ 1 × 10−15 cm2 s−1 and is effectively trapped by interstitial oxygen atoms. The concentration of implantation-induced defects increases linearly with dose but the defect production decreases at high enough dose rates. This dose rate effect depends on the ion mass and is qualitatively predicted by computer simulations of the defect reaction kinetics.
New Insight into Damage-Related Phenomena in Si Implanted Under Extreme Conditions
MRS Proceedings, 1995
New insight into damage formation in Si(100) during self-ion irradiation is gained from processing under extreme conditions. Dislocations form in the near-surface as a result of lattice relaxation in response to strain produced by precursor defects which are shown to be vacancy-type by positron analysis. A model to account for these defects and their distribution is presented. A novel technique is demonstrated which utilizes a subsequent implantation as a depth specific probe to manipulate the vacancy-type defects. Aspects of damage growth which emerge from the probe results are discussed.
Point defects observed in crystalline silicon implanted by MeV Si ions at elevated temperatures
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 1995
Si(100) samples of n-type have been implanted with 5.6 MeV 28Si3+ ions at elevated temperatures up to 400°C using doses of 107 to 109 cm−2. Deep level transient spectroscopy was utilized for sample analysis, and after implantation at 400°C, three new levels occur ∼0.22, ∼0.34 and ∼0.47 eV below the conduction band edge (Ec). Evidence is obtained for a high-order
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.
Silicon defects characterization for low temperature ion implantation and spike anneal processes
2014 20th International Conference on Ion Implantation Technology (IIT), 2014
In the last years a lot of effort has been directed in order to reduce silicon defects eventually formed during the ion implantation/anneal sequence used in the fabrication of CMOS devices. In this work we explored the effect of ion implant dose rate and temperature on the formation of silicon defects for high fluence 49 BF 2 implantations. The considered processes (implantation and annealing) conditions are those typically used to form the source/drain regions of p-channel transistors in the submicron technology node and will be detailed in the document. Characterization of implant damage and extended silicon defects left after anneal has been performed by TEM. Dopant distribution and dopant activation has been investigated by SIMS and SRP analysis. We have verified that implant dose rate and temperature modulate the thickness of the amorphous silicon observed after implant, as well as the concentrations of silicon defects left after anneal. Effect of high dose rate low temperature implantation on product device was also evaluated, showing a reduction of leakage current on p-channel transistors. Experimental set up, results and possible explanation will be reported and discussed in the paper.
Electrically active defects due to end-of-ion-range damage in silicon irradiated with MeV Ar + ions
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 1996
Damage induced by MeV Ar+ ion implantation and end of range defects in Si have been studied by capacitance-voltage, thermally stimulated capacitance, deep level transient spectroscopy (DLTS) and time analyzed transient spectroscopy (TATS). Unlike earlier studies, which focus on defects induced during post-implantation annealing steps, we study as-implanted p-type silicon samples. We report the occurrence of mid-gap acceptor levels using DLTS and TATS in a region well beyond the ion range. The presence of temperature dependent series resistance due to damaged region distorts DLTS lineshapes, even leading to sign reversal of DLTS peaks in some cases. A new and better method of correcting series resistance effects in capacitance transients has been employed. It is based on detecting the point of inversion of isothermal transients which are nonmonotonic due to the presence of series resistance. The capture process is found to be thermally activated with a high barrier energy. Possible origin of capture barrier and broadening in activation energy are discussed. Our results indicate that these deep levels are associated with point defects with local disorder in the neighbourhood.
Journal of Applied Physics, 2013
In this work, we focused on the analysis of implantation-induced defects, mainly small interstitial clusters (ICs) and {311} defects introduced in n-type Si after ion implantation using deep level transient spectroscopy (DLTS). Silicon ions (at 160 keV or 190 keV) of fluences ranging from (0.1-8.0) Â 10 13 cm À2 have been implanted into n-type Si and annealed at temperatures between 500 C and 800 C specifically to create small ICs or {311}s rod-like defects. In samples dominated by small ICs, DLTS spectra show prominent deep levels at Ec À 0.24 eV and Ec À 0.54 eV. After increasing the fluence and temperature, i.e., reducing the number of small ICs and forming {311} defects, the peak Ec À 0.54 eV is still dominant while other electron traps Ec À 0.26 eV and Ec À 0.46 eV are introduced. There were no observable deep levels in reference, non-implanted samples. The identity and origin of all these traps are interpreted in conjunction with recently developed predictive defect simulation models. V