F. Cristiano | University of Toulouse (original) (raw)

Papers by F. Cristiano

2005 13th International Conference on Advanced Thermal Processing of Semiconductors, 2005

MRS Proceedings, 2004

ABSTRACT The formation of ultra-shallow junctions (USJs) for future integrated circuit technologi... more ABSTRACT The 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.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1998

ABSTRACT A (100) silicon wafer was implanted with 150 keV 1.6×1015 Ge+/cm2 to produce 175 nm amor... more ABSTRACT A (100) silicon wafer was implanted with 150 keV 1.6×1015 Ge+/cm2 to produce 175 nm amorphous silicon followed by 65 keV carbon implants (Rp=175 nm) with various doses. After regrowth at 1000°C for 15 s the dechannelling due to residual defects was studied as a function of the carbon dose by accurate RBS-channelling and the data were analysed using the DICADA code and Transmission Electron Microscopy (TEM) measurements of dislocation loop densities. The present study reveals that the presence of carbon influences not only the End-of-Range (EoR) dislocation loops formed below the original amorphous/crystalline interface but also the randomly distributed point defects. The presence of carbon in both the top amorphised and regrown layer as well as the underlying substrate causes a reduction in the point defect density of 85% for the highest carbon dose of 1×1015 C+/cm2.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1998

ABSTRACT

Extended Abstracts - 2008 8th International Workshop on Junction Technology (IWJT '08), 2008

In this paper, we investigate the evolution of extended defects during a msec Flash anneal after ... more In this paper, we investigate the evolution of extended defects during a msec Flash anneal after a PAI implant and show that during the ultra-fast temperature ramp-up and ramp-down, the basic mechanisms that control the evolution of defects are not modified with respect to the relatively slower RTA anneals. In addition, we show that junction depths below 15 nm can

2009 Proceedings of the European Solid State Device Research Conference, 2009

In this work, the influence of the Silicon/Buried Oxide Interface (Si/BOX) on the electrical char... more In this work, the influence of the Silicon/Buried Oxide Interface (Si/BOX) on the electrical characteristics of Silicon-On-Insulator (SOI) MOSFETs is investigated by means of numerical simulations. Considering the state-of-art dopant diffusion models and the effect of Si/BOX interface as a point defect sink, process simulations were performed to investigate the two-dimensional diffusion behaviour of the dopant impurities. The impact of the Si/BOX interface on the shape of the different active zones profiles was investigated by analyzing the standard electrical characteristics of CMOS devices. Finally, a new electrical characterization methodology is detailed to better analyze dopants lateral diffusion profiles.

We review the structure and energetics of the extended defects found in ion implanted Si as a fun... more We review the structure and energetics of the extended defects found in ion implanted Si as a function of annealing conditions and show that the defect kinetics can be described by an Ostwald ripening process whereby the defects exchange Si atoms and evolve in size and type to minimize their formation energy. Finally, we present a physically based model to

Extended Abstracts - 2008 8th International Workshop on Junction Technology (IWJT '08), 2008

Ultra‐Shallow Junctions Fabrication by Plasma Immersion Implantation on PULSION® Followed by Lase... more Ultra‐Shallow Junctions Fabrication by Plasma Immersion Implantation on PULSION® Followed by Laser Thermal Processing. [AIP Conference Proceedings 1066, 473 (2008)]. Frank Torregrosa, Hasnaa Etienne, Guillaume ...

Applied Physics Letters, 2015

ABSTRACT Silicon carbide n-type metal-oxide-semiconductor field effect transistors (MOSFETs) with... more ABSTRACT Silicon carbide n-type metal-oxide-semiconductor field effect transistors (MOSFETs) with different p-body acceptor concentrations were characterized by Hall effect. Normally OFF MOSFETs with good transfer characteristics and low threshold voltage were obtained with a peak mobility of ∼145 cm2 V−1 s−1 for the lowest acceptor concentration. The results are explained in terms of an increase of Coulomb scattering centers when increasing the background doping. These scattering centers are associated to fixed oxide and trapped interface charges. Additionally, the observed mobility improvement is not related to a decrease of the interface states density as a function of background doping. A full-text version of the article can be found at publica.fraunhofer.de/documents/N-328016.html

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1996

2014 International Workshop on Junction Technology (IWJT), 2014

ABSTRACT The formation of extended defects and their impact on dopant activation in nanosecond la... more ABSTRACT The formation of extended defects and their impact on dopant activation in nanosecond laser annealed silicon is investigated. It is found that laser anneal favours the formation of “unconventional” (001) loops (typically not expected to occur in ion implanted silicon). (001) loops are formed near the liquid-solid interface (in the non-molten side region). Following non-melt anneals, these loops act as scattering centres, leading to carrier mobility degradation. In contrast, in the case of melt anneals, the molten region itself is of excellent crystalline quality, free of any large defects and leads to very high activation rates. Full melting of the implanted region leads to an almost perfectly recrystallized layer. Finally, we demonstrate how the internal stress generated in silicon during ultra-fast laser annealing in the ns regime can modify the fundamental mechanisms of defect formation and lead to the formation of these “unconventional” loops.

Solid-State Electronics, 2005

1998 International Conference on Ion Implantation Technology. Proceedings (Cat. No.98EX144), 1998

Abstract In this study the impact of the defect tails generated by germanium implantation into n-... more Abstract In this study the impact of the defect tails generated by germanium implantation into n-type silicon wafers on the deep energy states, the doping profiles and mobilities, are investigated. 100 mm (100) silicon wafers with a base doping concentration of 3× 10 15/ ...

Ion Beam Processing of Materials and Deposition Processes of Protective Coatings, 1996

Si/Si1-xGex/Si heterostructures which are potentially suitable for HBT fabrication have been synt... more Si/Si1-xGex/Si heterostructures which are potentially suitable for HBT fabrication have been synthesised by implanting Ge+ ions into a Si(100) substrate upon which a Si overlayer was deposited, followed by Si+-induced post-amorphization and low temperature Solid Phase Epitaxial Growth. RES and TEM investigations have shown that the Ge induced end-of-range (EOR) defects are annihilated during regrowth, as well as extended defects observed in some C+ co-implanted samples, resulting in good crystalline structures.

ABSTRACT A quantitative description of the transient diffusion and activation of boron during pos... more ABSTRACT A quantitative description of the transient diffusion and activation of boron during post-implantation annealing steps is one of the most challenging tasks. In industrially relevant situation, it needs to address diffusion at extrinsic concentrations, the agglomeration of self-interstitials, and the formation of boron-interstitial clusters. This article describes the experimental work performed or used to calibrate model parameters as independently as possible. The combined model is then applied to ultra-shallow junction formation by annealing boron implanted into crystalline or preamorphized silicon.

2013 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD), 2013

2005 13th International Conference on Advanced Thermal Processing of Semiconductors, 2005

MRS Proceedings, 2004

ABSTRACT The formation of ultra-shallow junctions (USJs) for future integrated circuit technologi... more ABSTRACT The 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.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1998

ABSTRACT A (100) silicon wafer was implanted with 150 keV 1.6×1015 Ge+/cm2 to produce 175 nm amor... more ABSTRACT A (100) silicon wafer was implanted with 150 keV 1.6×1015 Ge+/cm2 to produce 175 nm amorphous silicon followed by 65 keV carbon implants (Rp=175 nm) with various doses. After regrowth at 1000°C for 15 s the dechannelling due to residual defects was studied as a function of the carbon dose by accurate RBS-channelling and the data were analysed using the DICADA code and Transmission Electron Microscopy (TEM) measurements of dislocation loop densities. The present study reveals that the presence of carbon influences not only the End-of-Range (EoR) dislocation loops formed below the original amorphous/crystalline interface but also the randomly distributed point defects. The presence of carbon in both the top amorphised and regrown layer as well as the underlying substrate causes a reduction in the point defect density of 85% for the highest carbon dose of 1×1015 C+/cm2.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1998

ABSTRACT

Extended Abstracts - 2008 8th International Workshop on Junction Technology (IWJT '08), 2008

In this paper, we investigate the evolution of extended defects during a msec Flash anneal after ... more In this paper, we investigate the evolution of extended defects during a msec Flash anneal after a PAI implant and show that during the ultra-fast temperature ramp-up and ramp-down, the basic mechanisms that control the evolution of defects are not modified with respect to the relatively slower RTA anneals. In addition, we show that junction depths below 15 nm can

2009 Proceedings of the European Solid State Device Research Conference, 2009

In this work, the influence of the Silicon/Buried Oxide Interface (Si/BOX) on the electrical char... more In this work, the influence of the Silicon/Buried Oxide Interface (Si/BOX) on the electrical characteristics of Silicon-On-Insulator (SOI) MOSFETs is investigated by means of numerical simulations. Considering the state-of-art dopant diffusion models and the effect of Si/BOX interface as a point defect sink, process simulations were performed to investigate the two-dimensional diffusion behaviour of the dopant impurities. The impact of the Si/BOX interface on the shape of the different active zones profiles was investigated by analyzing the standard electrical characteristics of CMOS devices. Finally, a new electrical characterization methodology is detailed to better analyze dopants lateral diffusion profiles.

We review the structure and energetics of the extended defects found in ion implanted Si as a fun... more We review the structure and energetics of the extended defects found in ion implanted Si as a function of annealing conditions and show that the defect kinetics can be described by an Ostwald ripening process whereby the defects exchange Si atoms and evolve in size and type to minimize their formation energy. Finally, we present a physically based model to

Extended Abstracts - 2008 8th International Workshop on Junction Technology (IWJT '08), 2008

Ultra‐Shallow Junctions Fabrication by Plasma Immersion Implantation on PULSION® Followed by Lase... more Ultra‐Shallow Junctions Fabrication by Plasma Immersion Implantation on PULSION® Followed by Laser Thermal Processing. [AIP Conference Proceedings 1066, 473 (2008)]. Frank Torregrosa, Hasnaa Etienne, Guillaume ...

Applied Physics Letters, 2015

ABSTRACT Silicon carbide n-type metal-oxide-semiconductor field effect transistors (MOSFETs) with... more ABSTRACT Silicon carbide n-type metal-oxide-semiconductor field effect transistors (MOSFETs) with different p-body acceptor concentrations were characterized by Hall effect. Normally OFF MOSFETs with good transfer characteristics and low threshold voltage were obtained with a peak mobility of ∼145 cm2 V−1 s−1 for the lowest acceptor concentration. The results are explained in terms of an increase of Coulomb scattering centers when increasing the background doping. These scattering centers are associated to fixed oxide and trapped interface charges. Additionally, the observed mobility improvement is not related to a decrease of the interface states density as a function of background doping. A full-text version of the article can be found at publica.fraunhofer.de/documents/N-328016.html

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1996

2014 International Workshop on Junction Technology (IWJT), 2014

ABSTRACT The formation of extended defects and their impact on dopant activation in nanosecond la... more ABSTRACT The formation of extended defects and their impact on dopant activation in nanosecond laser annealed silicon is investigated. It is found that laser anneal favours the formation of “unconventional” (001) loops (typically not expected to occur in ion implanted silicon). (001) loops are formed near the liquid-solid interface (in the non-molten side region). Following non-melt anneals, these loops act as scattering centres, leading to carrier mobility degradation. In contrast, in the case of melt anneals, the molten region itself is of excellent crystalline quality, free of any large defects and leads to very high activation rates. Full melting of the implanted region leads to an almost perfectly recrystallized layer. Finally, we demonstrate how the internal stress generated in silicon during ultra-fast laser annealing in the ns regime can modify the fundamental mechanisms of defect formation and lead to the formation of these “unconventional” loops.

Solid-State Electronics, 2005

1998 International Conference on Ion Implantation Technology. Proceedings (Cat. No.98EX144), 1998

Abstract In this study the impact of the defect tails generated by germanium implantation into n-... more Abstract In this study the impact of the defect tails generated by germanium implantation into n-type silicon wafers on the deep energy states, the doping profiles and mobilities, are investigated. 100 mm (100) silicon wafers with a base doping concentration of 3× 10 15/ ...

Ion Beam Processing of Materials and Deposition Processes of Protective Coatings, 1996

Si/Si1-xGex/Si heterostructures which are potentially suitable for HBT fabrication have been synt... more Si/Si1-xGex/Si heterostructures which are potentially suitable for HBT fabrication have been synthesised by implanting Ge+ ions into a Si(100) substrate upon which a Si overlayer was deposited, followed by Si+-induced post-amorphization and low temperature Solid Phase Epitaxial Growth. RES and TEM investigations have shown that the Ge induced end-of-range (EOR) defects are annihilated during regrowth, as well as extended defects observed in some C+ co-implanted samples, resulting in good crystalline structures.

ABSTRACT A quantitative description of the transient diffusion and activation of boron during pos... more ABSTRACT A quantitative description of the transient diffusion and activation of boron during post-implantation annealing steps is one of the most challenging tasks. In industrially relevant situation, it needs to address diffusion at extrinsic concentrations, the agglomeration of self-interstitials, and the formation of boron-interstitial clusters. This article describes the experimental work performed or used to calibrate model parameters as independently as possible. The combined model is then applied to ultra-shallow junction formation by annealing boron implanted into crystalline or preamorphized silicon.

2013 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD), 2013