Volatile Evolution from Polymer Materials Induced by Irradiation with Accelerated He++ Ions

2004 ◽  
Vol 851 ◽  
Author(s):  
Julian.J. Murphy ◽  
Christopher.J. Wetteland
Keyword(s):  
Ion Beam ◽  
Surface Region ◽  
Energetic Particles ◽  
Thin Layers ◽  
Polymer Materials ◽  
Particle Radiation ◽  
Chemical Changes ◽  
Near Surface ◽  
Particle Irradiation ◽  
Pass Through

ABSTRACTExperimentally investigating ageing caused by irradiation with energetic particles is very difficult. Radioactive sources can be employed but these are difficult to handle and contaminate the material being irradiated precluding subsequent chemical and physical characterisation. The penetration of energetic particles also tends to be small so any change is localised in the near surface region so only a small amount of material is irradiated. Analysing changes in such thin layers causes a number of problems. To simulate ageing induced by particle radiation polymer samples have been exposed to fast He++ ions in an accelerated ion beam. The ions pass through a 10μm thick window of Havar foil before impacting upon the sample. Volatile species evolved from the materials upon bombardment are contained within the irradiation chamber by the foil window. Analysis of such species is shown to be a highly sensitive probe for investigating chemical changes in the exposed materials. A number of important chemical changes induced in polymer materials have been identified. Trends in the relative rates of volatile evolution have been identified which correlate with chemical changes identified in other radiation experiments. As these experiments are performed at far slower irradiation rates the large acceleration factors used in ion beam irradiation are discussed along with the implications for using ion beams to simulate alpha particle irradiation.

scholarly journals Site Specific Three-dimensional Structural Analysis in Tissues and Cells Using Automated DualBeam Slice &View

2007 ◽  
Vol 15 (2) ◽  
pp. 26-31 ◽  
Author(s):  
Ben Lich
Keyword(s):  
Electron Microscopy ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Three Dimensional ◽  
Surface Region ◽  
Dimensional Structure ◽  
Near Surface ◽  
Imaging Capability ◽  
Fluorescent Markers ◽  
Confocal And Electron Microscopy

DualBeam instruments that combine the imaging capability of scanning electron microscopy (SEM) with the cutting and deposition capability of a focused ion beam (FIB) provide biologists with a powerful tool for investigating three-dimensional structure with nanoscale (1 nm-100 nm) resolution. Ever since Van Leeuwenhoek used the first microscope to describe bacteria more than 300 years ago, microscopy has played a central role in scientists' efforts to understand biological systems. Light microscopy is generally limited to a useful resolution of about a micrometer. More recently the use of confocal and electron microscopy has enabled investigations at higher resolution. Used with fluorescent markers, confocal microscopy can detect and localize molecular scale features, but its imaging resolution is still limited. SEM is capable of nanometer resolution, but is limited to the near surface region of the sample.

Amortization and Recrystallization of 6H-SiC by ion Beam Irradiation

1994 ◽  
Vol 339 ◽  
Author(s):  
V. Heera ◽  
R. Kögler ◽  
W. Skorupa ◽  
J. Stoemenos
Keyword(s):  
Ion Irradiation ◽  
Ion Beam ◽  
Surface Region ◽  
Ion Beam Irradiation ◽  
Surface Layers ◽  
Near Surface ◽  
Transmission Electron ◽  
Amorphous Surface ◽  
Amorphous Sic

ABSTRACTThe evolution of the damage in the near surface region of single crystalline 6H-SiC generated by 200 keV Ge+ ion implantation at room temperature (RT) was investigated by Rutherford backscattering spectroscopy/chanelling (RBS/C). The threshold dose for amorphization was found to be about 3 · 1014 cm-2, Amorphous surface layers produced with Ge+ ion doses above the threshold were partly annealed by 300 keV Si+ ion beam induced epitaxial crystallization (IBIEC) at a relatively low temperature of 480°C For comparison, temperatures of at least 1450°C are necessary to recrystallize amorphous SiC layers without assisting ion irradiation. The structure and quality of both the amorphous and recrystallized layers were characterized by cross-section transmission electron microscopy (XTEM). Density changes of SiC due to amorphization were measured by step height measurements.

Pulsed Ion Beam Annealing of Metal and Silicide Thin Films on Silicon

1982 ◽  
Vol 40 ◽  
pp. 458-459
Author(s):  
L.J. Chen ◽  
L.S. Hung ◽  
J.W. Mayer
Keyword(s):  
Thin Films ◽  
Ion Beam ◽  
Surface Region ◽  
Molten Layer ◽  
Near Surface ◽  
Contact Materials ◽  
Energy Beam ◽  
Nickel Thin Films ◽  
Metal Silicides ◽  
Silicide Growth

Metal silicides have found increasing use in microelectronic industry as contact materials. Energy beam annealing offers controlled energy deposition in the near surface region so that silicide growth is achieved without heating the entire layer. When pulsed laser and electron at high power density were applied to metal-semiconductor systems, cellular structures have been formed with silicon columns surrounded by silicide walls as a result of the formation of the molten layer of metal and silicon followed by segregation due to constitutional supercooling as the melt front moves toward the surface. A wealth of microstructures were observed in pulsed ion beam annealed nickel thin films on silicon. An interface melting mechanism was invoked to explain the results. In this paper, we report further data on the subject.

Characterization of Si, SiGe and SOI Structures Using Photoluminescence

1999 ◽  
Vol 588 ◽  
Author(s):  
V. Higgs
Keyword(s):  
Focused Ion Beam ◽  
Secondary Ion Mass Spectrometry ◽  
Ion Beam ◽  
Surface Region ◽  
Misfit Dislocations ◽  
Near Surface ◽  
Pl Mapping ◽  
Excitation Laser ◽  
Pl Intensity ◽  
P Type

AbstractA new Photoluminescence (PL) method has been developed to detect defects in the near surface region of Si wafers and Si-on-insulator (SOI) structures. Wafer maps (up to 300 min diameter) can be readily acquired and areas of interest can be scanned at high resolution (≈1 μm). The excitation laser beam is modulated to confine the photogenerated carriers; defects are observed due to the localised reduction of the carrier lifetime. Si p-type (10 Ohm.cm) wafers were intentionally contaminated with various levels of Ni and Fe (1×109−5×1010 atoms/cm2) and annealed. The PL intensity was observed to decrease due to the metal related non-radiative defects. Whereas in contrast, for Cu, (1×109−5×1010 atoms/cm2) the PL intensity actually increased initially and reached a maximum value at 5×109 atoms/cm2. It is suggested that during contamination the Cu related defects have complexed with existing defects (that have stronger recombination properties) and increased the PL. Further Cu contamination (1×1010−5×1010 atoms/cm2) produced a reduction in the PL intensity. PL mapping of strained SiGe epilayers showed that misfit dislocations can be detected and PL can be used to evaluate material quality.PL maps of SOI bonded wafers revealed that the non-bonded areas, voids or gas bubbles could be detected. This was confirmed using defect etching and polishing, voids as small as ≈30 μm in diameter could be detected. SOI wafers fabricated using the separation by implanted oxygen (SIMOX) technique were also analysed, variations in the recombination properties of the layer could be observed. Further inspection using transmission electron microscopy (TEM) revealed that the defects were non-uniformities of the buried oxide covering several microns and containing tetrahedral stacking faults. Focused ion beam (FIB) milling and secondary ion mass spectrometry (SIMS) showed that these defects were at the Si/SiO2 interface and were chemically different to the surrounding area.

The Effects of Low Energy Ion-Beam Milling on the Physical and Electrical Properties of N-GaAs.

1995 ◽  
Vol 396 ◽  
Author(s):  
W.F. Seng ◽  
P.A. Barnes ◽  
M.L. Lovejoy ◽  
L.P. Fu ◽  
G.D. Gilliland ◽  
...  
Keyword(s):  
Ion Beam ◽  
Surface Region ◽  
Low Energy ◽  
Ion Milling ◽  
Ion Beam Etching ◽  
Near Surface ◽  
Contact Metallization ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Modification Of The Surface

AbstractLow energy neutral Ar ion-beam etching of n-GaAs was investigated as a possible “cleaning” procedure prior to contact metallization. The ion-beam source energy was varied between 35 eV and 1200 eV at a fixed current density of 1 mA/cm2. The effects of ion-milling on lightly doped n-GaAs were analyzed electrically by measuring current-voltage (IV) and capacitance-voltage (CV) characteristics of Schottky barriers formed after the ion-milling. The metal semiconductor barriers were prepared immediately following ion-milling without breaking vacuum. Photoluminescence and Rutherford Backscattering (RBS) were used to determine if any physical modification of the surface and near surface region of the ion-milled substrates had occurred.

INFLUENCE OF LOCAL MECHANICAL STRESSES ON THE SILICON SPUTTERING YIELD BY ION BEAM

2020 ◽  
Vol 55 ◽  
pp. 156-172
Author(s):  
A.A. Efremov ◽  
Keyword(s):  
Ion Beam ◽  
Stress Gradient ◽  
Surface Region ◽  
Elastic Interaction ◽  
Mechanical Stresses ◽  
Weakly Bound ◽  
Scientific Publications ◽  
Near Surface ◽  
Elastic Fields ◽  
Sputtering Yield

A review of scientific publications and modeling of the effect of mechanical stresses on the sputtering yield of silicon by an ion beam is carried out. It is shown that the flux of atoms (from the depth to the surface) through interstitial or vacancy mechanisms due to the stress gradient caused by the limiting bending of the plate is insufficient to explain the increase in the sputtering coefficient. Calculations show that even the limiting elastic deformations do not significantly change the energy of atom detachment from the site, and an increase in the drift velocity of atoms due to the enrichment of the near-surface region with vacancies is insufficient to increase the sputtering rate. Consequently, it is necessary that the elastic deformation is transformed into plastic with the formation of mobile weakly bound atoms. The calculated stress distribution in a loaded silicon wafer using the COMSOL Multiphysics software package showed that the key driving force behind the increase in the silicon sputtering coefficient is the concentration of compressive and tensile stresses in the vicinity of the simulated crater during sputtering. The created crater is a stress concentrator, the gradients of which significantly exceed the values obtained by bending a plate without a crater. It is demonstrated that the generated stresses exceed the ultimate strength of the material in the vicinity of the crater, which begins to relax due to the expulsion of "excess" atoms in the tension region. The appearance of additional deformation-stimulated fluxes of weakly bound surface atoms at the bottom and walls of the crater provides an increase in the concentration of knocked-out atoms in the process of ion sputtering. Simulations predict an increase in sputtering yield of up to 40%. It is also shown that closely spaced craters, due to elastic interaction with each other, compensate each other's elastic fields, which has an effect on the value of the sputtering coefficient.

Ion Beam Processing

MRS Bulletin ◽  
1987 ◽  
Vol 12 (2) ◽  
pp. 18-21
Author(s):  
C.W. White
Keyword(s):  
Ion Implantation ◽  
Large Scale ◽  
Wide Spectrum ◽  
Ion Beam ◽  
Semiconductor Industry ◽  
Surface Region ◽  
Ion Beams ◽  
Group V ◽  
Near Surface ◽  
Research Activities

Ion beams are used extensively in materials research for processing and synthesis as well as for characterization. In the last few years, enormous advances have been made regarding the use of ion beams for processing or synthesis, and this issue of the MRS BULLETIN will review some of those advances. (The use of ion beams for materials characterization will be the subject of a future issue of the BULLETIN.) The areas covered in this issue are ion implantation, ion beam mixing, ion-assisted deposition, and direct ion beam deposition. For each area, recognized experts in the field prepared overview articles that should be very interesting to those who are not active in the field, and that should be useful to other experts in the field.The first large-scale use of ion beams for materials modification took place in the semiconductor industry more than 20 years ago when ion implantation began to be used to dope the near-surface region of silicon with Group III or Group V dopants. The use of ion implantation in the semiconductor industry has undergone explosive growth, and today almost all electronic devices are fabricated utilizing at lest one ion implantation step.In addition to the semiconductor area, research is being carried out using ion implantation in a multitude of other areas which include ceramics, metals and alloys, insulators, etc. The article on “Ion Implantation” by S.T. Picraux and P.S. Peercy provides an excellent overview of current research activities involving ion implantation of a wide spectrum of materials.

scholarly journals EUV ablation of organic polymers at a high fluence

2014 ◽  
Vol 2 ◽  
Author(s):  
Chiara Liberatore ◽  
Klaus Mann ◽  
Matthias Müller ◽  
Ladislav Pina ◽  
Libor Juha ◽  
...  
Keyword(s):  
Extreme Ultraviolet ◽  
Preliminary Investigation ◽  
Surface Region ◽  
Polymer Materials ◽  
Near Surface ◽  
Polymer Molecules ◽  
Nanosecond Pulses ◽  
Volatile Products ◽  
Discharge Laser

Abstract A preliminary investigation on short-wavelength ablation mechanisms of poly(methyl methacrylate) (PMMA) and poly (1,4-phenylene ether ether-sulfone) (PPEES) by extreme ultraviolet (EUV) radiation at 13.5 nm using a table-top laser-produced plasma from a gas-puff target at LLG (Göttingen) and at 46.9 nm by a 10 Hz desktop capillary discharge laser operated at the Institute of Physics (Prague) is presented. Ablation of polymer materials is initiated by photo-induced polymer chain scissions. The ablation occurs due to the formation of volatile products by the EUV radiolysis removed as an ablation plume from the irradiated material into the vacuum. In general, cross-linking of polymer molecules can compete with the chain decomposition. Both processes may influence the efficiency and quality of micro(nano)structuring in polymer materials. Wavelength is a critical parameter to be taken into account when an EUV ablation process occurs, because different wavelengths result in different energy densities in the near-surface region of the polymer exposed to nanosecond pulses of intense EUV radiation.

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