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.

Atomic Scale Structure-Property Relationships of Defects and Interfaces in Ceramics

1998 ◽  
Vol 4 (S2) ◽  
pp. 556-557
Author(s):  
S. Stemmer ◽  
G. Duscher ◽  
E. M. James ◽  
M. Ceh ◽  
N.D. Browning
Keyword(s):  
Point Defects ◽  
High Resolution Electron Microscopy ◽  
Complete Characterization ◽  
Atomic Scale ◽  
Structure Property ◽  
Defect Engineering ◽  
Impurity Atoms ◽  
Structure Property Relationships ◽  
Resolution Electron ◽  
Scale Composition

The evaluation of the two dimensional projected atom column positions around a defect or an interface in an electronic ceramic, as it has been performed in numerous examples by (quantitative) conventional high-resolution electron microscopy (HRTEM), is often not sufficient to relate the electronic properties of the material to the structure of the defect. Information about point defects (vacancies, impurity atoms), and chemistry or bonding changes associated with the defect or interface is also required. Such complete characterization is a necessity for atomic scale interfacial or defect engineering to be attained.One instructive example where more than an image is required to understand the structure property relationships, is that of grain boundaries in Fe-doped SrTi03. Here, the different formation energies of point defects cause a charged barrier at the boundary, and a compensating space charge region around it. The sign and magnitude of the barrier depend very sensitively on the atomic scale composition and chemistry of the boundary plane.

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.

Ostwald Ripening of {113} Defects Precursors and Transient Enhanced Diffusion

1999 ◽  
Vol 568 ◽  
Author(s):  
Giovanni Manninoo ◽  
Nicholas E.B. Cowem ◽  
Peter A. Stolk ◽  
Fred Roozeboom ◽  
Hendrik G.A. Huizing ◽  
...  
Keyword(s):  
Point Defects ◽  
Ostwald Ripening ◽  
Ion Beam ◽  
Extended Defects ◽  
Defect Band ◽  
Enhanced Diffusion ◽  
Dissociation Energies ◽  
Marker Layer ◽  
High Supersaturation ◽  
Very High

ABSTRACTThe ripening of ion-beam generated point defects into extended defects has been investigated in detail. The interstitial supersaturation has been extracted from boron marker-layer diffusion after annealing under non-equilibrium defect conditions. We measured a very high initial supersaturation followed by a decrease over many orders of magnitude with a characteristic “plateau” related to the presence of {113} defects. A continuum inverse model has been used to properly describe the ripening of point defects into clusters and their evolution in the presence of a remote sink, e.g. the surface. It evidences that a nonconservative Ostwald ripening process takes place inside the defect band during the annealing and sustains the interstitial supersaturation. The model reveals moreover an oscillatory behaviour of dissociation energies of the nanometer-sized defects which are responsible for the initial high supersaturation. These defects are believed to be {113} precursors.

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.

Point and Extended Defect Interactions in Silicon

1997 ◽  
Vol 469 ◽  
Author(s):  
M. E. Law ◽  
S. K. Earles
Keyword(s):  
Point Defects ◽  
Quantitative Model ◽  
Extended Defects ◽  
Form Complex ◽  
Extended Defect ◽  
Enhanced Diffusion ◽  
Defect Interactions ◽  
Short Time ◽  
Surface Sink

ABSTRACTTransient Enhanced Diffusion (TED) is one of the biggest modeling challenges present in predicting scaled technologies. Damage from implantation of dopant ions changes the diffusivities of the dopants and precipitates to form complex extended defects. Developing a quantitative model for the defect behavior during short time, low temperature anneals is a key to explaining TED. The surface can play a defining role in the removal of point defects from the bulk, but there is a lot of controversy over the role and strength of the surface sink for point defects. The controversy will be reviewed, and new experimental results will be presented that investigate the role of the surface on TED.

Transient Enhanced Diffusion in B+ and P+ Implanted Silicon

1986 ◽  
Vol 74 ◽  
Author(s):  
S. J. Pennycook ◽  
R. J. Culbertson
Keyword(s):  
Heat Treatment ◽  
Point Defects ◽  
Diffusion Coefficients ◽  
Thermal Processing ◽  
Rapid Thermal Processing ◽  
Temperature Dependent ◽  
Enhanced Diffusion ◽  
Thermally Activated ◽  
Transient Enhanced Diffusion ◽  
And Diffusion

AbstractWe report the transient enhanced diffusion of supersaturated phosphorus in ion-implanted SPE grown Si. Precipitation proceeds rapidly to a metastable SiP phase, which can be converted to an orthorhombic form or redissolved by subsequent heat treatment. The effects are strongly temperature dependent, and consistent with the trapped interstitial model. The behavior of different dopants follows their relative interstitialcy diffusion coefficients. The results suggest that ion implantation induced point defects dominate over thermally activated point defects during low temperature and certain rapid thermal processing, controlling dopant deactivation and diffusion in crystalline or amorphous silicon, and can also affect the SPE growth rate.

SIMULATION OF BORON DIFFUSION IN THE NEAR-SURFACE REGION OF SILICON SUBSTRATE

2020 ◽  
Vol 27 (11) ◽  
pp. 2050010
Author(s):  
O. I. VELICHKO
Keyword(s):  
Silicon Crystal ◽  
Surface Region ◽  
Nonuniform Distribution ◽  
Boron Diffusion ◽  
Lattice Contraction ◽  
Near Surface ◽  
Enhanced Diffusion ◽  
Impurity Atoms ◽  
Proposed Model ◽  
The Difference

The mechanism of boron-enhanced diffusion from a thin boron layer deposited on the surface in the case of silicon crystal doping is proposed and investigated. It was supposed that lattice contraction occurs in the vicinity of the surface due to the difference between the atomic radii of boron and silicon. This lattice contraction provides a stress-mediated diffusion of silicon self-interstitials from the near-surface region to the bulk of a semiconductor. Due to the stress-mediated diffusion, the near-surface region is depleted of silicon self-interstitials, and simultaneous oversaturation of this species occurs in the bulk. In this way, a strong nonuniform distribution of silicon self-interstitials in the vicinity of the surface is formed without regard to the large migration length of this species. The oversaturation of the bulk of a semiconductor with nonequilibrium self-interstitials allows one to explain the boron-enhanced diffusion of impurity atoms. The strong nonuniform distribution of these point defects also results in a specific form of boron concentration profile in the vicinity of the surface. Good agreement of the calculated boron profile with the experimental data for the entire doped region was obtained within the limit of the proposed model.

Enhanced Diffusion in Silicon Processing

MRS Bulletin ◽  
2000 ◽  
Vol 25 (6) ◽  
pp. 39-44 ◽  
Author(s):  
Nicholas Cowern ◽  
Conor Rafferty
Keyword(s):  
Point Defects ◽  
Atomic Scale ◽  
Dopant Atom ◽  
Ideal Crystal ◽  
Crystalline Materials ◽  
Silicon Lattice ◽  
Enhanced Diffusion ◽  
Interstitial Atoms ◽  
Scale Point ◽  
Grade Silicon

Semiconductor-grade silicon is one of the most perfect crystalline materials that can be fabricated. It contains less than 1 ppb of unintended impurities and negligible twins or dislocations. Dopants can diffuse in this near-ideal crystal only by interacting with atomic-scale point defects: interstitial atoms or vacancies. These defects migrate through the silicon lattice, occasionally binding with a dopant atom and displacing it by one or more lattice positions.

Modeling of Dopant Diffusion during Annealing of Sub-Amorphizing Implants

1993 ◽  
Vol 316 ◽  
Author(s):  
Scott Dunham
Keyword(s):  
Point Defects ◽  
Model Development ◽  
Three Dimensional ◽  
Fabrication Process ◽  
Physical Models ◽  
Extended Defects ◽  
Enhanced Diffusion ◽  
Complicated Process ◽  
Parameter Values ◽  
Multiple Interactions

Ion implant annealing is a complicated process involving the interactions of point defects generated during the implantation, implanted or previously present dopants, and extended defects which form as a result of the implant damage. To effectively model the process, it is essential to determine the critical processes, assess the validity of assumptions and calculate appropriate parameter values. In addition, implant annealing is just one element in the VLSI fabrication process, and the model development must consider the process as part of the broad range of experimental observations, as it is only through consistent physical models that simulators can predict the multiple interactions and two and three-dimensional effects present in VLSI structures. This work focuses on enhanced diffusion following silicon implants below the amorphization threshold as a function of dose, energy and time.

Microstructural Evolution in Reduced TiO2

1981 ◽  
Vol 39 ◽  
pp. 74-75
Author(s):  
W. T. Donlon ◽  
S. Shinozaki ◽  
E. M. Logothetis ◽  
W. Kaizer
Keyword(s):  
Microstructural Evolution ◽  
Point Defects ◽  
Extended Defects ◽  
Small Deviations ◽  
Controlled Atmospheres ◽  
Limited Solubility ◽  
Thin Foils ◽  
Heat Treated ◽  
Porous Polycrystalline ◽  
Crystallographic Shear

Since point defects have a limited solubility in the rutile (TiO2) lattice, small deviations from stoichiometry are known to produce crystallographic shear (CS) planes which accomodate local variations in composition. The material used in this study was porous polycrystalline TiO2 (60% dense), in the form of 3mm. diameter disks, 1mm thick. Samples were mechanically polished, ion-milled by conventional techniques, and initially examined with the use of a Siemens EM102. The electron transparent thin foils were then heat-treated under controlled atmospheres of CO/CO2 and H2 and reexamined in the same manner.The “as-received” material contained mostly TiO2 grains (∼5μm diameter) which had no extended defects. Several grains however, aid exhibit a structure similar to micro-twinned grains observed in reduced rutile. Lattice fringe images (Fig. 1) of these grains reveal that the adjoining layers are not simply twin related variants of a single TinO2n-1 compound. Rather these layers (100 - 250 Å wide) are alternately comprised of stoichiometric TiO2 (rutile) and reduced TiO2 in the form of Ti8O15, with the Ti8O15 layers on either side of the TiO2 being twin related.

Sign in / Sign up

Export Citation Format

Share Document