Analysis of low energy boron implants in silicon through SiO2 films: implantation damage and anomalous diffusion

Kaabi, L.; Gontrand, Christian; Remaki, B.; Seigneur, F.; Balland, B.

doi:10.1016/0026-2692(94)90042-6

Cited by 9 publications

(2 citation statements)

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“…Creation of an amorphous layer can reduce channelling during the implant and the transient enhanced diffusion during the damage annealing step that follows the implant [7]. The current densities obtainable using the differential mode are 3 to 4 times higher than those reported in [7] using the conventional drift mode. It is unlikely, therefore, that in the case presented here that the Si surface will amorphise.…”

Section: Introductionmentioning

confidence: 75%

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Anomalous Diffusion of Ultra low Energy Boron Implants in Silicon

et al. 1997

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Ultra low energy boron implants (0.2 to 3 keV) have been carded out on Si (100) at doses between 1x10 14 cm-2 and 1x10 15 cm-2 using xRLEAP. The samples were annealed at temperatures between 900 0 C and 10500C. The atomic profiles of these samples was measured using SIMS. Monte Carlo and diffusion simulations were performed using the SSupreme code. Comparisons between the simulations and experimental measurements show interesting differences these are discussed. IntroductionUltra shallow junctions are required by the microelectronics industry with depths below 0.1uum[1]. Low energy implantation is currently the most credible means available to obtain these low junction depths. The boron implants presented here were performed using the Applied Materials xRLEAP ion implanter in drift and differential modes [2,3]. The carrier and atomic profiles of the as implanted and annealed wafers were examined using Secondary Ion Mass Spectrometry (SIMS). SIMS makes a measure of the atomic profile and has an excellent dynamic range, but has a tendency to broaden the deeper edge of the profile due to atomic mixing problems in the ion erosion process. This becomes more of a problem the shallower the profile. The secondary ion production process is normally enhanced by using an oxygen beam, however, the secondary ion signal can be dominated in the early stages of the erosion process by the build up of an implanted surface oxide layer. This again restricts the accuracy of profiling shallow implanted layers. We also make a comparison with model predictions using the industry standard process simulation tools. Process simulation tools have proved very successful in predicting both the as implanted and thermally activated profiles resulting from implantations above 5 keV. There have also been some recent reports [4,5] that by suitable modification of a standard Binary Collision model the as implanted profiles can be well predicted for implants even as low as 250 eV and that there is little need to consider the complex many body interactions to determine the initial stopping place of implanted atoms. It has been pointed out recently [6], however, that the defect density, especially close to the surface may not be adequately modelled as yet in this way. As the diffusion of B is determined by the defect population it is quite likely that this inadequacy in the models will give rise to inaccuracies in the modelling of the thermal treatment of shallow implants in close proximity to the surface. Experimental Si (100) wafers were implanted with Boron at energies between 0.2 keV and 3 keV. All the wafers implanted in this work have received no surface pre-treatment or pre-amorphisation. They were HF dipped before introduction to the implantation chamber to ensure uniform surface conditions. The 0.2 and 0.5 keV implants were performed using differential mode while the I and 3 keV implants were performed using the drift mode. Analysis of implant profiles of the same energy using either mode show no observable differences. Dose rates were kept a...

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Section: Introductionmentioning

confidence: 75%

“…Evidence from recent studies [7,8] shows that implantation with high dose rates, high beam current density, can help in amorphising the surface of Si. Creation of an amorphous layer can reduce channelling during the implant and the transient enhanced diffusion during the damage annealing step that follows the implant [7].…”

Section: Introductionmentioning

confidence: 98%