Ultra-Low Energy Boron Implants in Crystalline Silicon: Atomic Transport Properties and Electrical Activation

1999 ◽  
Vol 568 ◽  
Author(s):  
E. Napolitani ◽  
A. Carnera ◽  
V. Privitera ◽  
A. La Magna ◽  
E. Schroer ◽  
...  
Keyword(s):  
Transport Properties ◽  
Point Defects ◽  
Crystalline Silicon ◽  
Low Energy ◽  
Electrical Activation ◽  
Epitaxial Silicon ◽  
High Concentration ◽  
Enhanced Diffusion ◽  
Atomic Transport ◽  
Wide Range

ABSTRACTWe investigated the atomic transport properties and electrical activation of boron in crystalline epitaxial silicon after ultra-low energy ion implantation (0.25–1 keV) and rapid thermal annealing (750–1100 °C). A wide range of implant doses was investigated (3×1012-1×105/cm2). A fast Transient Enhanced Diffusion (TED) pulse is observed involving the tail of the implanted Boron, the profile displacement being dependent on the implant dose. The excess of interstitials able to promote enhanced diffusion of implanted boron occurs, provided the implant dose is high enough to generate a significant total number of point defects. The Boron diffusion following the fast initial TED pulse can be described by the equilibrium diffusion equations.The electrical activation of ultra-shallow implants is hard to achieve, due to the high concentration of dopant and point defects confined in a very shallow layer that significantly contributes to the formation of clusters and complex defects. Provided a correct combination of annealing temperatures and times for these ultra-shallow implants is chosen, however, a sheet resistance 500 Δ/square with a junction depth below 0.1μm can be obtained, which has a noteworthy technological relevance for the future generations of semiconductor devices.

Low Energy Implantation and Transient Enhanced Diffusion: Physical Mechanisms and Technology Implications

1997 ◽  
Vol 469 ◽  
Author(s):  
N. E. B. Cowern ◽  
E. J. H. Collart ◽  
J. Politiek ◽  
P. H. L. Bancken ◽  
J. G. M. Van Berkum ◽  
...  
Keyword(s):  
Thermal Activation ◽  
Crystalline Silicon ◽  
Cmos Technology ◽  
Low Energy ◽  
Defect Engineering ◽  
Enhanced Diffusion ◽  
Physical Mechanisms ◽  
Transient Enhanced Diffusion ◽  
Junction Formation ◽  
Silicon Cmos

ABSTRACTLow energy implantation is currently the most promising option for shallow junction formation in the next generations of silicon CMOS technology. Of the dopants that have to be implanted, boron is the most problematic because of its low stopping power (large penetration depth) and its tendency to undergo transient enhanced diffusion and clustering during thermal activation. This paper reports recent advances in our understanding of low energy B implants in crystalline silicon. In general, satisfactory source-drain junction depths and sheet resistances are achievable down to 0.18 micron CMOS technology without the need for implantation of molecular species such as BF2. With the help of defect engineering it may be possible to reach smaller device dimensions. However, there are some major surprises in the physical mechanisms involved in implant profile formation, transient enhanced diffusion and electrical activation of these implants, which may influence further progress with this technology. Some initial attempts to understand and model these effects will be described.

What Does Self-Diffusion Tell Us about Ultra Shallow Junctions?

2000 ◽  
Vol 610 ◽  
Author(s):  
Ant Ural ◽  
Serene Koh ◽  
P. B. Griffin ◽  
J. D. Plummer
Keyword(s):  
Point Defects ◽  
High Concentration ◽  
Enhanced Diffusion ◽  
Self Diffusion ◽  
Native Point Defects ◽  
Junction Formation ◽  
Ultra Shallow Junctions ◽  
High Concentrations ◽  
Temperature Furnace ◽  
Dopant Profiles

AbstractUnderstanding the coupling between native point defects and dopants at high concentrations in silicon will be key to ultra shallow junction formation in silicon technology. Other effects, such as transient enhanced diffusion (TED) will become less important. In this paper, we first describe how thermodynamic properties of the two native point defects in silicon, namely vacancies and self-interstitials, have been obtained by studying self-diffusion in isotopically enriched structures. We then discuss what this tells us about dopant diffusion. In particular, we show that the diffusion of high concentration shallow dopant profiles is determined by the competition between the flux of mobile dopants and those of the native point defects. These fluxes are proportional to the interstitial or vacancy components of dopant and self-diffusion, respectively. This is why understanding the microscopic mechanisms of silicon self-diffusion is important in predicting and modeling the diffusion of ultra shallow dopant profiles. As an example, we show experimental data and simulation fits of how these coupling effects play a role in the annealing of shallow BF2 ion implantation profiles. We conclude that relatively low temperature furnace cycles following high temperature rapid thermal anneals (RTA) have a significant effect on the minimum junction depth that can be achieved.

A Comparison of Low Energy BF2 Implantation in Si and Ge Preamorphized Silicon

1988 ◽  
Vol 128 ◽  
Author(s):  
Gary A. Ruggles ◽  
Shin-Nam Hong ◽  
Jimmie J. Wortman ◽  
Mehmet Ozturk ◽  
Edward R. Myers ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Crystalline Silicon ◽  
Amorphous Layer ◽  
Low Energy ◽  
Electrical Activation ◽  
Silicon Substrates ◽  
Boron Diffusion ◽  
Junction Depth ◽  
Rapid Thermal Anneal ◽  
Boron Segregation

ABSTRACTLow energy (6 keV) BF2 implantation was carried out using single crystal, Ge-preamorphized, and Si-preamorphized silicon substrates. Implanted substrates were rapid thermal annealed at temperatures from 600°C to 1050'C and boron channeling, diffusion, and activation were studied. Ge and Si preamorphization energies were chosen to produce nearly identical amorphous layer depths as determined by TEM micrographs (approximately 40 nm in both cases). Boron segregation to the end-of-range damage region was observed for 6 keV BF2 implantation into crystalline silicon, although none was detected in preamorphized substrates. Junction depths as shallow as 50 nm were obtained. In this ultra-low energy regime for ion implantation, boron diffusion was found to be as important as boron channeling in determining the junction depth, and thus, preamorphization does not result in a significant reduction in junction depth. However, the formation of junctions shallower than 100 rmu appears to require RTA temperatures below 1000°C which can lead to incomplete activation unless the substrate has been preamorphized. In the case of preamorphized samples, Hall measurements revealed that nearly complete electrical activation can be obtained for preamorphized samples after a 10 second rapid thermal anneal at temperatures as low as 600°C.

scholarly journals Diffusion Engineering by Carbon in Silicon

2000 ◽  
Vol 610 ◽  
Author(s):  
Ulrich Goesele ◽  
Pierre Laveant ◽  
Rene Scholz ◽  
Norbert Engler ◽  
Peter Werner
Keyword(s):  
Point Defects ◽  
Crystalline Silicon ◽  
Bipolar Transistor ◽  
Precipitation Behavior ◽  
High Concentration ◽  
Intrinsic Point Defects ◽  
Influence Diffusion ◽  
Carbon Precipitation ◽  
Equilibrium Concentrations ◽  
Diffusion Mechanisms

AbstractThe possibility to suppress undesirable diffusion of the base dopant boron in siliconbased bipolar transistor structures by the incorporation of a high concentration of carbon has lead to renewed interest in the behavior of carbon in crystalline silicon. The present paper will review essential features of carbon in silicon including solubility, diffusion mechanisms and precipitation behavior. Based on this information the possibilities to use carbon to influence diffusion of dopants in silicon by the introduction of non-equilibrium concentrations of intrinsic point defects will be discussed as well as the reason for the relatively high resilience against carbon precipitation. Interactions between carbon and oxygen will be mentioned, especially in the context of an as yet unexplained fast out-diffusion of carbon close to the surface.

scholarly journals Annealing of Boron-Doped Hydrogenated Crystalline Silicon Grown at Low Temperature by PECVD

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3795 ◽  
Author(s):  
Marta Chrostowski ◽  
José Alvarez ◽  
Alessia Le Donne ◽  
Simona Binetti ◽  
Pere Roca i Cabarrocas
Keyword(s):  
Low Temperature ◽  
Crystalline Silicon ◽  
Chemical Vapor ◽  
Dark Conductivity ◽  
Silicon On Insulator ◽  
Doping Profile ◽  
Epitaxial Silicon ◽  
High Concentration ◽  
Boron Doped ◽  
Soi Substrates

We investigate low-temperature (<200 °C) plasma-enhanced chemical vapor deposition (PECVD) for the formation of p–n junctions. Compared to the standard diffusion or implantation processes, silicon growth at low temperature by PECVD ensures a lower thermal budget and a better control of the doping profile. We previously demonstrated the successful growth of boron-doped epitaxial silicon layers (p+ epi-Si) at 180 °C. In this paper, we study the activation of boron during annealing via dark conductivity measurements of p+ epi-Si layers grown on silicon-on-insulator (SOI) substrates. Secondary Ion Mass Spectroscopy (SIMS) profiles of the samples, carried out to analyze the elemental composition of the p+ epi-Si layers, showed a high concentration of impurities. Finally, we have characterized the p+ epi-Si layers by low-temperature photoluminescence (PL). Results revealed the presence of a broad defect band around 0.9 eV. In addition, we observed an evolution of the PL spectrum of the sample annealed at 200 °C, suggesting that additional defects might appear upon annealing.

The Source of Transient Enhanced Diffusion in Sub-keV Implanted Boron in Crystalline Silicon

2000 ◽  
Vol 610 ◽  
Author(s):  
E. Napolitani ◽  
A. Carnera ◽  
V. Privitera ◽  
E. Schroer ◽  
G. Mannino ◽  
...  
Keyword(s):  
Surface Layer ◽  
Annealing Temperature ◽  
Crystalline Silicon ◽  
Point Of View ◽  
Low Energy ◽  
Implantation Energy ◽  
Enhanced Diffusion ◽  
Decay Constants ◽  
Transient Enhanced Diffusion ◽  
Activation Annealing

AbstractThe transient enhanced diffusion (TED) during activation annealing of ultra low energy implanted boron (0.5 keV & 1 keV, 1×1013/cm2 & 1×1014/cm2) in silicon is investigated in detail. Annealing in the temperature range from 450°C to 750°C is either performed directly after implantation or after the removal of a surface layer before annealing. The kinetics revealed two regimes of enhanced diffusion ruled by different decay constants and different activation energies. The dependence of these two processes on implantation energy and annealing temperature is described and explained from the microscopical point of view. The annealings performed after surface layer removal, revealed that the defects responsible for the faster diffusion are located deeper than the defects responsible for the slower process.

A Model for Boron T.E.D. in Silicon: Full Couplings of Dopant with Free and Clustered Interstitials

2002 ◽  
Vol 717 ◽  
Author(s):  
F. Boucard ◽  
D. Mathiot ◽  
E. Guichard ◽  
P. Rivallin
Keyword(s):  
Point Defects ◽  
Diffusion Mechanism ◽  
Low Energy ◽  
The Self ◽  
Large Set ◽  
Dopant Diffusion ◽  
Experimental Conditions ◽  
Enhanced Diffusion ◽  
Equilibrium Reactions ◽  
Fully Coupled

AbstractIn this contribution we present a model for transient enhanced diffusion of boron in silicon. This model is based on the usual pair diffusion mechanism including non-equilibrium reactions between the dopant and the free point defects, taking into account their various charge states. In addition to, and fully coupled with the dopant diffusion we model the growth and dissolution of the interstitials and boron interstitials clusters associated with the anneal of the self-interstitial supersaturation created by the implantation step. It is thus possible to simulate a rather large set of experimental conditions, from conventional predeposition steps, to RTA after low energy implantation.

Defects and Diffusion in Silicon: An Overview

1999 ◽  
Vol 568 ◽  
Author(s):  
N.E.B. Cowern ◽  
G. Mannino ◽  
P.A. Stolk ◽  
M.J.J. Theunissen
Keyword(s):  
Point Defects ◽  
Technology Development ◽  
Silicon Crystal ◽  
Atomic Scale ◽  
Extended Defects ◽  
High Concentration ◽  
Concentration Gradients ◽  
Enhanced Diffusion ◽  
Impurity Atoms ◽  
And Diffusion

ABSTRACTAt the current pace of semiconductor technology development, transistor dimensions in advanced IC products will approach the range of a few tens of nanometers within the next decade. This presents a major challenge for our understanding of defects and diffusion in these tiny devices during processing. In response, an almost explosive growth in research on process physics has taken place at universities, national institutes and industry research labs worldwide. The central issue is the phenomenon of nonequilibrium diffusion driven by processing steps such as oxide growth, high concentration gradients of impurities, and annealing of damage caused by ion implantation. Nonequilibrium diffusion arises from perturbations to the natural thermal equilibrium concentrations of point defects - interstitial atoms and vacancies - in the silicon crystal. This paper gives a snapshot of our current understanding of the atomic-scale interactions between point defects and impurity atoms, extended defects and interfaces, as revealed by recent experimental and theoretical studies. The paper emphasizes the important role played by defect cluster ripening during transient enhanced diffusion and dopant activation.

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