Strengths and Limitations of the Vacancy Engineering Approach for the Control of Dopant Diffusion and Activation in Silicon

2008 ◽  
Vol 1070 ◽  
Author(s):  
Alain Claverie ◽  
Fuccio Cristiano ◽  
Mathieu Gavelle ◽  
Fabrice Sévérac ◽  
Frédéric Cayrel ◽  
...  
Keyword(s):  
Ostwald Ripening ◽  
Solubility Limit ◽  
High Energy ◽  
Dopant Diffusion ◽  
Boron Diffusion ◽  
Significant Control ◽  
Alternative Approach ◽  
Silicon Excess ◽  
Ultra Shallow Junctions ◽  
Activation Annealing

ABSTRACTThe fabrication of highly doped and ultra-shallow junctions in silicon is a very challenging problem for the materials scientist. The activation levels which are targeted are well beyond the solubility limit of current dopants in Si and, ideally, they should not diffuse during the activation annealing. In practice, the situation is even worse and when boron is implanted into silicon excess Si interstitial atoms are generated which enhance boron diffusion and favor the formation of Boron-Silicon Interstitials Clusters (BICs). An elegant approach to overcome these difficulties is to enrich the Si layers where boron will be implanted with vacancies before or during the activation annealing. Spectacular results have been recently brought to the community showing both a significant control over dopant diffusion and an increased activation of boron in such layers. In general, the enrichment of the Si layers with vacancies is obtained by Si+ implantation at high energy. We have recently developed an alternative approach in which the vacancies are injected from populations of empty voids undergoing Ostwald ripening during annealing. While different, the effects are also spectacular. The goal of this work is to establish a fair evaluation of these different approaches under technologically relevant conditions. The application domains of both techniques are discussed and future directions for their development/improvement are indicated.

Current Understanding and Modeling of B Diffusion and Activation Anomalies in Preamorphized Ultra-Shallow Junctions

2004 ◽  
Vol 810 ◽  
Author(s):  
B. Colombeau ◽  
A.J. Smith ◽  
N.E.B. Cowern ◽  
B.J. Pawlak ◽  
F. Cristiano ◽  
...  
Keyword(s):  
Ostwald Ripening ◽  
Current Understanding ◽  
High Dose ◽  
Driving Mechanism ◽  
Dopant Diffusion ◽  
Junction Depth ◽  
Extended Defect ◽  
Wide Range ◽  
Shallow Junctions ◽  
Ultra Shallow Junctions

ABSTRACTThe formation of ultra-shallow junctions (USJs) for future integrated circuit technologies requires preamorphization and high dose boron doping to achieve high activation levels and abrupt profiles. To achieve the challenging targets set out in the semiconductor roadmap, it is crucial to reach a much better understanding of the basic physical processes taking place during USJ processing. In this paper we review current understanding of dopant-defect interactions during thermal processing of device structures – interactions which are at the heart of the dopant diffusion and activation anomalies seen in USJs. First, we recall the formation and thermal evolution of End of Range (EOR) defects upon annealing of preamorphized implants (PAI). It is shown that various types of extended defect can be formed: clusters, {113} defects and dislocation loops. During annealing, these defects exchange Si interstitial atoms and evolve following an Ostwald ripening mechanism. We review progress in developing models based on these concepts, which can accurately predict EOR defect evolution and interstitial transport between the defect layer and the surface. Based on this physically based defect modelling approach, combined with fully coupled multi-stream modelling of dopant diffusion, one can perform highly predictive simulations of boron diffusion and de/re-activation in Ge-PAI boron USJs. Agreement between simulations and experimental data is found over a wide range of experimental conditions, clearly indicating that the driving mechanism that degrades boron junction depth and activation is the dissolution of the interstitial defect band. Finally, we briefly outline some promising methods, such as co-implants and/or vacancy engineering, for further down-scaling of source-drain resistance and junction depth.

Boron Ted in Pre-Amorphised SI: Role of the A/C Interface

1998 ◽  
Vol 532 ◽  
Author(s):  
D. Mathiot ◽  
C. Bonafos ◽  
M. OMRI ◽  
D. Alquier ◽  
A. Martinez ◽  
...  
Keyword(s):  
Ostwald Ripening ◽  
The Self ◽  
Experimental Results ◽  
Extended Defects ◽  
Dopant Diffusion ◽  
Boron Diffusion ◽  
Nucleation Stage ◽  
Diffusion Enhancement

ABSTRACTIn this paper we first review the main experimental results concerning boron diffusion in preamorphised silicon, focusing on the role played by the End Of Range defects. It is then shown that the application of the Ostwald ripening theory to the particular geometry of these defects permits to understand why and how they affect dopant diffusion. Contradictory experimental results can be reconciled if one considers that most of the diffusion enhancement occurs during the nucleation stage of the extended defects, and that the amorphous / crystalline interface is a perfect screen for the diffusion of the self-interstitials.

Stability of Ultra-Thin Gate Oxides with Boron Doped Polysilicon Gate Structures After Rapid Thermal Annealing

1993 ◽  
Vol 303 ◽  
Author(s):  
Bojun Zhang ◽  
Dennis M. Maher ◽  
Mark S. Denker ◽  
Mark A. Ray
Keyword(s):  
Thermal Annealing ◽  
Rapid Thermal Annealing ◽  
Depth Profiling ◽  
Gate Oxide ◽  
Annealing Condition ◽  
Dopant Diffusion ◽  
Boron Diffusion ◽  
Gate Oxides ◽  
Diffusion Behavior ◽  
Polysilicon Gate

ABSTRACTWe report a systematic study of dopant diffusion behavior for thin gate oxides and polysilicon implanted gate structures. Boron behavior is emphasized and its behavior is compared to that of As+ and BF2+. Dopant activation is achieved by rapid thermal annealing. Test structures with 100 Å, 60 Å and 30 Å gate oxides and ion implanted polysilicon gate electrodes were fabricated and characterized after annealing by SIMS, SEM, TEM, and C-V rpeasurements. For arsenic implanted structures, no dopant diffusion through a gate oxide of 30 Å thickness and an annealing condition as high as 1 100*C/1Os was observed. For boron implanted structures, as indicated by SIMS depth profiling, structures annealed at 1000*C/10s exhibit a so-called critical condition for boron diffusion through a 30 Å gate oxide. Boron dopant penetration is clearly observed for 60 Å gate oxides at an annealing condition of 1050 0C/10s. The flatband voltage shift can be as high as 0.56 volts as indicated by C-V measurements for boron penetrated gate oxides. However, 100 Å gate oxides are good diffusion barriers for boron at an annealing condition of 1100°C/10s. For BF2 implanted structures, the diffusion behavior is consistent with behavior reported in the literature.

scholarly journals Progress in Synthesizing Analogues of Nitrogenase Metalloclusters for Catalytic Reduction of Nitrogen to Ammonia

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 939
Author(s):  
Yang
Keyword(s):  
Energy Consumption ◽  
Catalytic Reduction ◽  
High Energy ◽  
Ambient Conditions ◽  
Promising Alternative ◽  
Fossil Energy ◽  
Alternative Approach ◽  
Increasing Demand ◽  
High Energy Consumption ◽  
Significant Opportunity

Ammonia (NH3) has played an essential role in meeting the increasing demand for food and the worldwide need for nitrogen (N2) fertilizer since 1913. Unfortunately, the traditional Haber–Bosch process for producing NH3 from N2 is a high energy-consumption process with approximately 1.9 metric tons of fossil CO2 being released per metric ton of NH3 produced. As a very challenging target, any ideal NH3 production process reducing fossil energy consumption and environmental pollution would be welcomed. Catalytic NH3 synthesis is an attractive and promising alternative approach. Therefore, developing efficient catalysts for synthesizing NH3 from N2 under ambient conditions would create a significant opportunity to directly provide nitrogenous fertilizers in agricultural fields as needed in a distributed manner. In this paper, the literature on alternative, available, and sustainable NH3 production processes in terms of the scientific aspects of the spatial structures of nitrogenase metalloclusters, the mechanism of reducing N2 to NH3 catalyzed by nitrogenase, the synthetic analogues of nitrogenase metalloclusters, and the opportunities for continued research are reviewed.

Evolution of Ion Beam Synthesized Au Nanoclusters in SiO2 under Ion Irradiation

2000 ◽  
Vol 647 ◽  
Author(s):  
Bernd Schmidt ◽  
Karl-Heinz Heinig ◽  
Arndt Mücklich
Keyword(s):  
Size Distribution ◽  
Ostwald Ripening ◽  
Ion Irradiation ◽  
Kinetic Monte Carlo ◽  
Ion Beam ◽  
Thick Layer ◽  
High Energy ◽  
Au Nanoclusters ◽  
Post Irradiation ◽  
Mean Size

AbstractThe evolution of the mean size and the size distribution of Au nanoclusters (NCs) under high-energy ion irradiation has been studied. Au NCs were synthesized in a 480 nm thick SiO2 layer by 330 keV Au+ implantation and subsequent annealing at T = 1000 °C for 1h in dry O2. XTEM images show a 70 nm thick layer of Au NCs, being centered at the projected ion range Rp(330keV) = 100 nm, having a mean NC size of 5 nm at Rp, and resembling the broad Lifshiz-Slyozov-Wagner (LSW) size distribution of diffusion controlled Ostwald ripening. Post-irradiation of the Au NCs by 4.5 MeV gold ions was used in order to tailor their size and size distribution. The high-energy Au+ irradiations were performed at 190...210 °C with a fluence of (0.5...1.0)×1016 cm-2. By the post-irradiation no gold was deposited into the SiO2 layer, the Au+ ions come to rest in the (001)Si substrate at Rp(4.5MeV) = 1 [.proportional]m. XTEM images of the post-irradiated Au NCs show a strong decrease of their mean size as well as the width of their size distribution. The observed NC evolution under ion irradiation agrees with recent theoretical predictions and kinetic Monte-Carlo simulations.

Application of High Energy Ion Beam on the Control of Boron Diffusion

2003 ◽  
Vol 792 ◽  
Author(s):  
Wei-Kan Chu ◽  
Lin Shao ◽  
Jiarui Liu
Keyword(s):  
Point Defect ◽  
Point Defects ◽  
Anomalous Diffusion ◽  
Ion Beam ◽  
Surface Region ◽  
High Energy ◽  
Boron Diffusion ◽  
Defect Engineering ◽  
Projected Range ◽  
Ultrashallow Junction

ABSTRACTAnomalous diffusion of boron during annealing is a detriment on the fabrication of ultrashallow junction required by the next generation Si devices. This has driven the need to develop new doping methods. In the point defect engineering approach, high-energy ion bombardments inject vacancies near the surface region and create excessive interstitials near the end of projected range of incident ions. Such manipulation of point defects can retard boron diffusion and enhance activation of boron. We will review the current understanding of boron diffusion and our recent activities in point defect engineering.

Effect of Fluorine on the Dopant Diffusion of Through-Oxtoe Implanted Boron in Si - a Correlation with Microstructural Defects

1992 ◽  
Vol 262 ◽  
Author(s):  
J. G. Huang ◽  
A. Lam ◽  
R. J. Jaccodine
Keyword(s):  
Strain Gradient ◽  
Dopant Diffusion ◽  
Boron Diffusion ◽  
Spreading Resistance ◽  
Oxygen Precipitation ◽  
Microstructural Defects ◽  
Oxygen Atoms

ABSTRACTIn case of boron through-oxide implant, it has been shown that the knocked-in oxygen atoms segregate at initially nucleated dislocation sites during the incubation and no significant junction movement is detected. The trapping of oxygen proceeds up to a certain time at which oxygen-precipitation occurs and this leads to an ejection of excess Si interstitials and further enhancing boron diffusion. However, with fluorine addition we believe that fluorine incorporation in SiO2 and/or SiO2/Si interface not only releases the strain gradient but also suppresses the silicon interstitials ejection and by this means suppresses the oxidation-enhanced boron diffusion. Correlated results of TEM microdefect structures and spreading resistance profiles are used to further support our postulation.

IN SITU STUDIES OF EPITAXIAL GROWTH BY SYNCHROTRON X-RAY DIFFRACTION

2006 ◽  
Vol 13 (02n03) ◽  
pp. 155-166 ◽  
Author(s):  
WOLFGANG BRAUN ◽  
KLAUS H. PLOOG
Keyword(s):  
Ostwald Ripening ◽  
Crystal Surface ◽  
High Energy ◽  
Molecular Beam Epitaxy Growth ◽  
X Rays ◽  
Surface Kinetics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Kinetics Of

X-rays are ideal to study the structure of crystals due to their weak interaction with matter and in most cases allow a quantitative analysis using kinematical theory. To study the incorporation of atoms during crystal growth and to analyze the kinetics on the crystal surface high primary beam intensities available at synchrotrons are required. Our studies of the molecular beam epitaxy growth of III–V semiconductors reveal that, despite their similarity in crystal structure, the surface kinetics of GaAs (001), InAs (001) and GaSb (001) differ strongly. GaAs shows an unexpectedly large coarsening exponent outside the predicted range of Ostwald ripening models during recovery. GaSb exhibits dramatically different surface morphology variations during growth and recovery. Overgrowth of GaAs by epitaxial MnAs demonstrates the ability of X-ray diffraction to follow an interface as it is buried during heteroepitaxy, which is not possible by reflection high-energy electron diffraction.

Ultra-Shallow Junctions for the 65nm Node Based on Defect and Stress Engineering

2005 ◽  
Vol 864 ◽  
Author(s):  
Victor Moroz ◽  
Majeed Foad ◽  
Houda Graoui ◽  
Faran Nouri ◽  
Dipu Pramanik ◽  
...  
Keyword(s):  
Stress Gradient ◽  
Process Window ◽  
Boron Diffusion ◽  
High Concentration ◽  
Stress Effects ◽  
Ion Channeling ◽  
Rapid Temperature ◽  
Ultra Shallow Junctions ◽  
High Concentrations ◽  
Non Equilibrium

AbstractThe co-implantation of germanium, carbon, and boron with the optimum implant energies and doses makes it possible to create p+/n junctions with the sheet resistance of less than 600 Ohm/square and the slope of less than 3 nm/decade. The narrow process window is based on careful engineering of the amorphization, point defects, and stresses and includes standard 1050°C spike annealing. The germanium pre-amorphization suppresses the ion channeling for the subsequent boron implant. The tensile stress induced by the substitutional carbon atoms and the compressive stress induced by the substitutional germanium atoms slow down boron diffusion and help to make the junctions shallower. The stress gradient in the transition region from the strained carbon and germanium doped layers to the relaxed silicon underneath creates an uphill boron flux that makes the junction slope steeper.The optimum amount of carbon is placed in between the implanted boron and the implant damage, which is located below the amorphized layer. During the annealing, the carbon atoms capture silicon interstitials that are coming from the implant damage and form carbon-interstitial clusters. The analysis demonstrates that it is possible to capture over 95% of the interstitials this way before they have a chance to reach boron-doped layer. This completely suppresses the transient-enhanced boron diffusion (TED) and drastically reduces the amount of boron that is deactivated in boron-interstitial clusters (BICs). In fact, the point defect engineering with an optimized carbon profile allows to remove all non-equilibrium silicon interstitials that are generated by the following three sources: the implant damage below the amorphized layer, the rapid temperature ramp down, and the interstitials generated by boron at high concentrations (due to the effect known as boron-enhanced diffusion (BED)).The latter effect leads to significant increase of the apparent boron activation level beyond the well-characterized solid-state solubility level. We explain this effect as a reduction in formation of BICs due to the lack of interstitial supersaturation. In carbon-free silicon, high concentration boron is always accompanied by the non-equilibrium interstitials, coming from either the implant damage or the BICs even if boron is introduced into silicon by pre-deposition instead of the implantation. Extensive experiments and theoretical analysis based on simulation of the interaction of Ge, C, I, and B atoms, as well as the stress effects, point to the optimized process flow that improves the shape and parameters of the p+/n USJs.

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