Recent Progress with Surface Analysis by Laser Ionization

1986 ◽  
Vol 69 ◽  
Author(s):  
Christopher H. Becker

AbstractThis paper briefly reviews previous results and developments, then presents new results, using a novel surface analytical technique that uses non-resonant multiphoton ionization (MPI) of neutral atoms and molecules sputtered by an ion beam, or desorbed by an electron beam or laser beam. In this method, which we call surface analysis by laser ionization (SALI), the non-resonant MPI, or “laser ionization,” is coupled with state-of-the-art time-of-flight mass spectrometry to provide extremely sensitive, general, and readily quantifiable surface analysis. Examples are presented for two applications relevant to the semiconductor industry and for the analysis of the near surface region of two specially pretreated stainless steels. A discussion also describes the favorable prospects for implementation of SALI with submicron dimension liquid metal ion beams for microanalysis, including situations with electron beam sensitive samples.

MRS Bulletin ◽  
1987 ◽  
Vol 12 (2) ◽  
pp. 18-21
Author(s):  
C.W. White

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.


2007 ◽  
Vol 15 (2) ◽  
pp. 26-31 ◽  
Author(s):  
Ben Lich

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.


1994 ◽  
Vol 339 ◽  
Author(s):  
V. Heera ◽  
R. Kögler ◽  
W. Skorupa ◽  
J. Stoemenos

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.


2004 ◽  
Vol 851 ◽  
Author(s):  
Julian.J. Murphy ◽  
Christopher.J. Wetteland

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.


2016 ◽  
Vol 23 (2) ◽  
pp. 321-328 ◽  
Author(s):  
David R. Diercks ◽  
Brian P. Gorman ◽  
Johannes J. L. Mulders

AbstractSix precursors were evaluated for use as in situ electron beam-induced deposition capping layers in the preparation of atom probe tomography specimens with a focus on near-surface features where some of the deposition is retained at the specimen apex. Specimens were prepared by deposition of each precursor onto silicon posts and shaped into sub-70-nm radii needles using a focused ion beam. The utility of the depositions was assessed using several criteria including composition and uniformity, evaporation behavior and evaporation fields, and depth of Ga+ ion penetration. Atom probe analyses through depositions of methyl cyclopentadienyl platinum trimethyl, palladium hexafluoroacetylacetonate, and dimethyl-gold-acetylacetonate [Me2Au(acac)] were all found to result in tip fracture at voltages exceeding 3 kV. Examination of the deposition using Me2Au(acac) plus flowing O2 was inconclusive due to evaporation of surface silicon from below the deposition under all analysis conditions. Dicobalt octacarbonyl [Co2(CO)8] and diiron nonacarbonyl [Fe2(CO)9] depositions were found to be effective as in situ capping materials for the silicon specimens. Their very different evaporation fields [36 V/nm for Co2(CO)8 and 21 V/nm for Fe2(CO)9] provide options for achieving reasonably close matching of the evaporation field between the capping material and many materials of interest.


2019 ◽  
Vol 813 ◽  
pp. 25-30
Author(s):  
Kai Li ◽  
Peng Fei Fu ◽  
Zhen Yun Tang ◽  
Bo Zhang ◽  
Yan Long Ma ◽  
...  

Electron beam Surfi-SculptTM is a novel surface treatment technique applied to produce high level performance Composite-Metal-Weld (ComeldTM) joints. Investigation on forming process during electron beam Surfi-SculptTM on Ti-6Al-4V alloy showed protrusions were formed via a layer-by-layer mode like additive manufacturing process. The near-surface region of electron beam Surfi-Sculpted Ti-6Al-4V alloy was occupied by fusion zone, heat-affected zone and base metal from the outermost surface to the underlying bulk alloy. The microstructure of fusion zone was characterized by a high density of fine acicular martensite phase, leading to a higher micro-hardness. A heat-affected zone was sandwiched between fusion zone and the underlying base metal, with different microstructural features compared to both fusion zone and the base metal.


Author(s):  
L.J. Chen ◽  
L.S. Hung ◽  
J.W. Mayer

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.


1999 ◽  
Vol 588 ◽  
Author(s):  
V. Higgs

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.


2011 ◽  
Vol 17 (5) ◽  
pp. 718-727 ◽  
Author(s):  
Douglas C. Meier ◽  
Jeffrey M. Davis ◽  
Edward P. Vicenzi

AbstractMineral borates, the primary industrial source of boron, are found in a large variety of compositions. One such source, kernite (Na2B4O6(OH)2·3H2O), offers an array of challenges for traditional electron-probe microanalysis (EPMA)—it is hygroscopic, an electrical insulator, composed entirely of light elements, and sensitive to both low pressures and the electron beam. However, the approximate stoichiometric composition of kernite can be analyzed with careful preparation, proper selection of reference materials, and attention to the details of quantification procedures, including correction for the time dependency of the sodium X-ray signal. Moreover, a reasonable estimation of the mineral's water content can also be made by comparing the measured oxygen to the calculated stoichiometric oxygen content. X-ray diffraction, variable-pressure electron imaging, and visual inspection elucidate the structural consequences of high vacuum treatment of kernite, while Auger electron spectroscopy and X-ray photoelectron spectroscopy confirm electron beam-driven migration of sodium and oxygen out of the near-surface region (sampling depth ≈ 2 nm). These surface effects are insufficiently large to significantly affect the EPMA results (sampling depth ≈ 400 nm at 5 keV).


1995 ◽  
Vol 396 ◽  
Author(s):  
W.F. Seng ◽  
P.A. Barnes ◽  
M.L. Lovejoy ◽  
L.P. Fu ◽  
G.D. Gilliland ◽  
...  

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.


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