Traditional coil-based eddy-current sensors are severely limited in their ability to detect small buried defects, defects under fasteners and deeply buried cracks and corrosion. TPL has developed eddy-current sensors and arrays based on the use of Giant Magnetoresistance (GMR) sensor elements. GMR offers high sensitivity, very wide bandwidth and low noise from DC to over 1 GHz. Coupled with the ability to fabricate GMR sensors with micron-level dimensions, these new eddy-current sensors offer an ideal technology for inspections requiring high spatial resolution and low-frequency, deeply-penetrating fields.

A magnetic-based non-destructive evaluation (NDE) method, which employs Barkhausen effect and measurement of the hysteresis loops, is used to correlate the magnetic and mechanical properties of ultra low carbon (ULC) steel. In particular, the NDE method was used to detect small deviations from linearity that occur in the stress-strain curve well below the 0.2% offset strain, and which generally defines the yield point in materials. Results show that three parameters: jumpsum and jumpsum rate (derived from the Barkhausen spectrum), and the relative permeability (derived from the B-H loops) varies sensitively with small permanent strains, and can be related to the plastic deformation in ULC steels. Investigation of micromagnetic structure revealed that plastic deformation leaves a residual stress state in the samples; the associated magneto-elastic energy makes the favorable easy axis of magnetization in a given grain to be the one that lies closest to the tensile axis. The consequence of this realignment of domains is that wall motion becomes intergranular in nature (as opposed to intragranular in unstrained samples). As a result, the more complex grain boundaries instead of dislocations, become the dominant pinning sites for domain walls. These observations provide a microscopic interpretation of the observed changes in the measured magnetic properties.

Using a scanning Hall-sensor microscope with an active area 50pμm × 50μm, we succeeded in visualizing a breakdown of paramagnetic austenite-phase in 304 stainless steels induced by a plastic strain at room temperature, resulting from a transformation to ferromagnetic martensite-phase. Magnetic images of spontaneous magnetic fields on a surface of strained sample show the degree and the place (and/or the extent) of phase breakdown. Furthermore, the images nearly agree with the calculated results for the principal shear stress rather than the principal stress under plastic deformation, indicative of the driving force of this breakdown. The study should open a way for non-destructive evaluation of 304 stainless steels.

Infrared thermography is a non-destructive investigation technique, which is largely used because of the outstanding advantages that it is capable to provide in a variety of applications and especially for conservation purposes of historic monuments, where destructive sectioning is prohibited. In the present work, dual band infrared thermography (3–5.4 μm and 8–12 μpm) is used, to evaluate the humidity distribution by capillary rise in reference samples of porous materials in lab, in order to validate the examination of real scale material systems in situ. The combined study of vapor/moisture transport in prototypes simulating porous materials under controlled environmental conditions (Relative Humidity 60–80% & Temperature 25–40°C), provides interpretation tools to the investigation by IR Thermography of transport phenomena occurring at the masonry. The cross-investigation of consolidated porous stones and of repair mortars, in lab and in situ on historic monuments in Greece, permits to evaluate the performance of conservation materials, regarding their compatibility to the porous building stones on historic masonries. It is deduced that Infrared Thermography by recording thermal maps of the real surfaces under study provides information on the differential behavior of the various materials on the masonry scale regarding the water impregnation and evaporation phenomena, which control the weathering effects in porous media. Hence, infrared thermography might be used as a nondestructive technique to evaluate on a micro and macro scale the performance of conservation interventions and materials, in compatibility to the original materials on the level of the structures.

A combination of cold neutron prompt gamma-ray activation analysis (PGAA) and neutron incoherent scattering (NIS) has been used for nondestructive characterization of hydrogen as a function of position in slabs of wet concrete of different compositions. Hydrogen was determined by PGAA by scanning each sample across a 5 mm diameter neutron beam in 10 mm increments, and measuring the 2223 keV prompt gamma ray. NIS measurements were performed by scanning the sample across a 5 mm diameter neutron beam at 5 mm increments and detecting scattered neutrons. The measurements demonstrate the feasibility of the techniques for 2D compositional mapping of hydrogen and other elements in materials, and indicate the potential of these methods for monitoring the uniformity of drying concrete.

Atomic Force Acoustic Microscopy is a near-field technique which combines the ability in using ultrasonics to image elastic properties with the high lateral resolution of scanning probe microscopes. We present a technique to measure the contact stiffness and the Young's modulus of sample surfaces quantitatively with a resolution of approximately 20 rum exploiting the contact resonance frequencies of standard cantilevers used in Atomic Force Microscopy. The Young's modulus of nanocrystalline ferrite films have been measured as a function of oxidation temperature. Furthermore images showing the domain structure of piezoelectric lead zirconate titanate ceramics have been taken.

An all-optical technique based on laser excitation and detection of surface acoustic waves is capable of precise, fast, noncontact and nondestructive measurements of metal film thickness. The technique is integrated into a compact and robust instrument. Applications to metal interconnect process control in integrated circuit technology are presented.

A new scanning probe method for evaluating the local carrier concentration of semiconductors is presented. The distance between a semiconductor surface and a vibrating tip is changed sinusoidally, and is adjusted to as small as a few nm across which tunneling current IT flows between the semiconductor surface and the vibrating tip. Displacement current ID due to the change in electric flux from the semiconductor surface to the vibrating tip flows periodically in accordance with the vibration of the tip. IT also flows when the distance becomes minimum. Both IT and ID flow simultaneously when a d.c. tip voltage V is applied, and these two currents are separated by using a two-phase lock-in amplifier. ID-V curve is analyzed by taking into account two-dimensional electric flux profile under the tip. In the tip voltage range within which majority carriers are accumulated, ID-V curve is extrapolated by a straight line. On the contrary, the slope of the curve decreases as the tip voltage is reduced from the voltage range of the accumulation, indicating that the majority carriers are depleted at the center of the Si surface. The theoretical ID-V curves are in good agreement with the measurement in the tip voltage region where the majority carriers are both accumulated and depleted. The local carrier concentration is able to be determined by makingthe theoretical ID-V curve fit the experimental results without contacting the semiconductor surface.

A newly-developed technique for the simultaneos characterization of the oxide-silicon interface properties and of bulk impurities was used for a systematic study of the nitridation process of thin oxides. This technique is based upon surface recombination velocity measurements, and does not require the formation of a capacitor structure, so it is very suitable for the characterization of as-grown interfaces.

Oxides grown both in dry and in wet enviroments were considered, and nitridation processes in N2O and in NO were compared to N2 annealing processes. The effect of nitridation temperature and duration were also studied, and RTO/RTN processes were compared to conventional furnace nitridation processes.

Surface recombination velocity was correlated with nitrogen concentration at the oxide-silicon interface obtained by Secondary Ion Mass Spectroscopy (SIMS) measurements. Surface recombination velocity (hence surface state density) decreases with increasing nitrogen pile-up at the oxide-silicon interface, indicating that in nitrided interfaces surface state density is limited by nitridation. NO treatments are much more effective than N2O treatments in the formation of a nitrogen-rich interface layer and, as a consequence, in surface state reduction.

Surface state density was measured in fully processed wafers before and after constant current stress. After a complete device process surface states are annealed out by hydrogen passivation, however they are reactivated by the electrical stress, and surface state results after stress were compared with data of surface recombination velocity in as-processed wafers.

A nondestructive method for estimating quality of single-crystal Si ingots is proposed. The method provides a three-dimensional pattern of the lifetime and diffusion length of charge carriers inside Si ingots up to 300 mm in diameter and I m in length. The method employs optical probing of ingots with laser-emitted radiation and includes laser-induced photoinjection of charge carriers followed by laser-assisted monitoring of their spatial distributions and time evolution in any part of the ingot about 1 cm in size.

Carrier lifetimes provide an excellent indication of the concentration of impurities and defects in semiconducting materials. This paper describes a non-contact technique for measuring generation and recombination lifetimes. This technique, which is incorporated into the KLATencor Quantox system, provides a highly sensitive method for monitoring the formation of defects or incorporation of impurities in silicon wafers during processing. Several applications of these measurements are investigated, such as monitoring the effects of various thermal cycles on the formation of a high-lifetime denuded zone near the wafer surface and monitoring diffusion furnace contamination after a quartz change.

Small signal non-contact ac-SPV method for monitoring near surface doping (NSD) in silicon has recently been introduced in commercial diagnostic tools. High chopping frequency light with a submicron penetration depth is used to generate small SPV signal and this signal is in turn monitored using a transparent pickup electrode. This technique has the advantage of producing fast, non-destructive full wafer measurement. Under certain conditions, the magnitude of this ac-SPV signal is inversely proportional to the depletion layer capacitance. If a depletion layer barrier height is known this allows the calculation of the concentration of ionized donors or acceptors in the depletion layer. NSD measurements by ac-SPV method were typically done for doping concentrations up to about 1016 cm−3. Only recently this range has been extended to 1018 cm−3, making it a very attractive technique for monitoring low and medium dose implants and especially for wafer scale mapping of implant uniformity and activation efficiency. In addition, the frequency dependence of the SPV signal provides a mean for evaluating the minority carrier lifetime in the near surface region of bulk and epitaxial wafers.

The influence of surface/interface traps upon small ac-SPV signal has never been fully understood. This paper quantifies the role of interface traps in the monitoring of NSD. The effect of typical surface treatments such as HF, SCI and SCI+SC2 wafer cleans are examined.

TPL has developed a method and instrumentation system for characterizing the surface area and pore size distribution of a thin-film or coating in its as-deposited state. Errors associated with destructive removal of the film are avoided and small sample sizes can be utilized with high-fidelity results.

Under conditions of a vacuum simulation it was investigated how electric rocket thruster (ERT) SPT-70 contaminates space craft (SC) surfaces. The contamination content in the ERT jet was studied by using solid targets. The film composition was analysed by Rutherford backscattering spectroscopy (RBS) He+ ions and nuclear reaction analysis (NRA) with H+ ions methods. Using the results of this analysis a preliminary estimation of the composition and the angular distribution of contaminated components in the ERT jet were carried out.

Material properties depend on their fabricated structure and orientation. It is thus important to develop rapid nondestructive techniques that will both allow determination of the orientation fabricated, and identify any changes that occur over time as a result of subsequent in service environmental conditions.

The present study examines the relationship between the thermal penetration time and planarity in polyimide films. Polyimides are advanced materials that have good high temperature stability, excellent dimensional stability, and excellent mechanical, electrical, and chemical resistance properties. The samples tested were specially prepared to range in orientation from three dimensionally random to highly planar. The molecular structure and orientation in the polyimide film was characterized by polarizing microscope techniques, while the thermal penetration time measurements utilized a new rapid nondestructive modified hot wire instrument.

This correlation will be the first time thermal penetration time has been measured by modified hot wire techniques and related to the internal structure of a polyimide. The work contributes to a deeper theoretical understanding of heat transfer mechanisms as they relate to orientation. Thermal penetration time evaluation could provide a new tool in the arsenal of structural characterization techniques.

This relationship between thermal penetration time and orientation is key for film manufacturers. Such a correlation has potential to speed the development cycles of new materials and assure properties during production and end-use applications.

Process induced crystal defects in silicon wafers can be detected by their stress fields. The nondestructive photoelasticity based on laser polarimetry is applied to visualize the stress fields of temperture gradient induced lattice defects like sliplines or extended defect areas around boat marks. The quantitative evaluation of the defects allows their characterization by a specific danger potential for further evolution causing upstream problems in IC manufacturing.

A key to the ultimate technological applications of core-shell nanoparticle materials is the understanding of the structure-property correlation. This work focuses on the characterizations of the structural properties for composite thin films derived from gold nanoparticles and thiolates using infrared reflectance spectroscopic (IRS) and electron spin resonance (ESR) techniques. IRS provides information on molecular packing and ordering of the shell components in the films, which relates to the molecular interactions and interfacial reactivities. ESR probes the conduction electron spin resonance properties of the nanosized cores, which can be correlated with the network or environmental electronic effects on the crystal cores. Results are discussed in terms of their correlation with the nanoparticle core sizes and the organic shell functionality.

Spectroscopic ellipsometry (SE) is a commonly used non-destructive, non-invasive in-situ sensor for dry etching. SE measures the change in the polarization state of light reflected from a surface. Sample thickness is obtained by fitting a model to the experimental ellipsometry data. In this paper we describe the design, testing and evaluation of an SE based adaptive real time feedback controller for etch rate regulation in CF4/O2 plasma etching of silicon nitride films. The feedback variable is the current etch rate as determined from the in-situ SE measurements of the film's thickness. The controller compensates for drifts in etch rate which occur during a given etch, and adaptively adjusts for the run-to-run variability inherent to plasma processing. Experimental results are presented and discussed.

The formation and thermal stability of Ni- and Ni(Pt) silicide on narrow polycrystalline Si (poly-Si) lines have been investigated using the non-destructive micro-Raman technique. The presence of Ni or Ni(Pt)Si on poly-Si lines with linewidths ranging from 0.5 gtm to 0.25 μm has been monitored by a distinct Raman peak at around 215 cm−1. Ni(Pt)Si was clearly identified to be present up to a RTA temperature of 900°C on narrow poly-Si lines as compared to pure NiSi which was found only up to 750°C. Raman scattering from the 100×100 μm2 poly-Si pads showed the formation of NiSi2 at 750°C for pure Ni-salicidation and 900°C for Ni(Pt)-salicidation respectively. The difference in the stability of NiSi on the poly-Si pads and lines is discussed in terms of agglomeration, inversion and/or nucleation of NiSi2that could be due to difference in nucleation sites and/or stress. In addition, a correlation between the line sheet resistance and the presence of Ni silicide was found using micro-Raman mapping along single poly-Si lines.

High quality epitaxial Sil−xGex/Si (x = 0.09 to 0.27) samples were studied with polarized Raman scattering technique. The LO (longitudinal optical) -TO (transversal optical) phonon mode splitting due to the tetragonal strain imposed by the lattice mismatch between Sil−xGex and Si was observed for the first time in such structures. In contrast to the case of uniaxial stress, the biaxial stress induces a larger strain frequency shift for the LO mode than for the TO mode. The phonon strain shift coefficient for the LO mode was found to be 1010 cm−1, which is larger than most of the values reported in the literatures, and almost composition independent throughout the range of x≤0.27. We argue that the smaller LO strain shift coefficients indicate that the Sil−xGex films used in previous work were partially relaxed.