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Inkjet printing technique has been applied to the production of magnetic layers and structures consisting of nanosized magnetic particles. These magnetic particles were synthesised by chemical meth ...

Pulsed-laser-induced removal of particles from surfaces is a new cleaning technique. This laser cleaning can be performed on dry surfaces as well as on wet surfaces with a micron-thick liquid film during pulsed laser irradiation to provide enhanced removal efficiency. Using the latter technique, to be called ‘steam laser cleaning’ here, we are able to remove epoxy, alumina, silicon or gold particles with diameters in the range 0.1–10 μm from silicon and other surfaces.

We have used a pulsed dye-laser beam at 6010 A, of 1-microsec duration and less, similar-mJ energy, to produce a line plasma in a Cs metal vapor. This produces a line source of large thermal energy. The heat diffusion after the laser pulse can be studied by transmission monitoring of a weak cw He-Ne laser beam that is parallel to but separated from the pulsed laser beam by an adjustable displacement. This is possible because the He-Ne beam is absorbed by the minority Cs(2) molecules but not by the majority Cs atoms; as the heat pulse diffuses through the probe beam, the transient temperature increase causes a corresponding change in the population distribution of the Cs(2) molecules and hence a transient increase in transmission of the probe beam. In other words, the Cs(2) works like a thermometer. Our work demonstrates a new and simple method to measure heat diffusion in a well-defined geometry, and it is especially suitable for use in a hot corrosive system because it is a noncontact method.

Laser cleaning was demonstrated to be a new, promising approach to efficiently remove particulate contamination of micron and submicron size from wafer surfaces as well as from the surface and trenches of thin silicon membrane stencil masks as used for e-beam projection lithography.

This paper presents the characterization and modeling of inkjet printed interconnects on flexible polyimide substrate using nano-particle silver ink for low-cost RFID applications. Then TDR/TDT and S-parameter measurements are performed at high frequency from 30 kHz to 6 GHz. A lumped equivalent circuit and distributed parameter model of the printed interconnects have been developed for the realization of the full printed RFID tags. Additionally the related electrical properties of the printed interconnects are extracted.

This work is focused on frequency domain electrical characterization of ink-jet printed coplanar waveguides (CPWs). The waveguides were designed and printed using conductive nanosilver ink at room temperature and sintered at 300degC. Distributed models, dependent on frequency, have been developed and some relevent parameters such as impedance, attenuation, are derived over frequency band from 30 kHz to 6 GHz. Two different widths of ground planes are investigated to examine the effects on CPW high frequency behaviors. In addition to these the obtained parameters have been compared and validated by theoretical calculations and momentum simulations.

Ferrofluids containing superparamagnetic Fe3O4 nanoparticles have been prepared by a controlled co-precipitation method.The aggregation of the particles was prevented by using a polymeric starch network as a coating agent. Structural and magnetic measurements reveal a particle size of around 6 nm, with a clear evidence of a uniform particle coating. The ferrofluids have been used as a contrast agent for MR imaging in biological tissue.

Laser cleaning with pulsed ultraviolet and infrared lasers is successfully employed to remove particulate contamination from silicon wafer surfaces and from delicate lithography membrane masks. Particulate material investigated include latex, alumina, silicon, and gold. Gold particles as small as 0.2 μm can be effectively removed. This new and highly efficient laser cleaning is achieved by choosing a pulsed laser with short pulse duration (without causing substrate damage), and a wavelength that is strongly absorbed by the surface; the removal efficiency is further enhanced by depositing a liquid film of thickness on the order of micron on the surface just before the pulsed laser irradiation.

Particulate contamination is a major yield loss factor in the manufacturing of microelectronic, data-storage, and other hi-tech devices. A single particle as small as 0.1 μm in size can cause complete micro-electronic circuit failure, or seriously degrade read/write performance of magnetic storage devices or even result in a crash of the magnetic head. Standard cleaning techniques, typically performed in liquid baths, have two major drawbacks: first, there is limited cleaning efficiency for submicron particles, and secondly, liquid baths tend to redeposit or even add new particles to the submersed surface. ‘Laser cleaning’, a technique currently being developed, appears capable of overcoming the above shortcomings. We observe that, particles of size 10 - 0.1 μm can be efficiently removed from various surfaces, and there is no need for a liquid bath. The technique we studied is based on the use of -pulsed infrared or ultraviolet lasers to explode a thin liquid film which is condensed onto the surface to be cleaned. Such explosion was studied in detail with nanosecond thermometry, photoacoustic detection, and fast photography. Momentum transfer from the expanding steam to the particles on the surface is believed to be the cause for the ejection of the particles. Ejection to ‘macroscopic’ distances (exceeding a few mm) from the surface facilitates particle collection procedures and thus prevents redeposition; this is of importance for practical application of ‘laser cleaning’.

The cross-sections of excited-state absorption have been measured for several tertiary amines. The high values found explain the unsuccessful attempts to obtain laser action in KrF-laser pumped vapors of tertiary amines.

The spectral and laser characteristics of 14 CH3-, CF3-, and F-substitutedp-terphenyls have been investigated. 2,2″-dimethyl-p-terphenyl in cyclohexane solution exhibits a shortest tuned laser wavelength of 311.2 nm, thus extending the range of dye laser emission by 1000 cm−1 in the uv. Peak output powers of 1.5 MW and 14% conversion efficiency at 332 nm were obtained under KrF-laser pumping in an untuned cavity.

Stimulated electronic Raman scattering in Ba vapour is used to efficiently convert the output of a XeCl excimer laser (308 nm) to the blue region (475 nm). Photon conversion efficiencies of up to 20% and output energies in the blue greater than 5 mJ are obtained. The multi-line structure of the XeCl laser emission is reproduced in the generated Stokes spectrum.

Noncontact techniques of optical probing of photoacoustic pulses provide new opportunities for ultrasonic and/or spectroscopic measurement in hostile environments (e.g., flames, corrosive fluids, dangerous aerosols, etc.) and also basic understanding of photoacoustic generation processes. This paper provides examples of such applications in the new field of 'optical ultrasonics' (whereby ultrasonic determinations of flows, temperatures, etc., are measured optically), including 'optical ultrasonic spectroscopy' (whereby ultrasonic dispersion and relaxations are measured optically).

A mask-to-wafer gap measurement technique has been implemented in the Electron Beam Proximity Printing (EBP) 0.5 /um lithography system. This technique does not use additional (optical) systems but the wide, parallel EBP-system e-beam, which performs scanning inclinations about a periodic chip-registration pattern in the mask, so that the image of that mask pattern is scanned across the wafer surface. The strong scattering/reflection of electrons from the e-beam, that occurs when the image overlaps a corresponding etch-pattern on the wafer surface, is detected and allows to monitor the image excursions in the wafer plane as a function of e-beam inclination. This in turn yields a measure for the mask to wafer gap. The accuracy of our gap sensing technique was found to be ± 1 %.

An electro-optical shutter, consisting of one Pockels cell between a pair of crossed polarisers is described which slices out two pulses of independently variable pulse widths and variable delay between them from an incident laser beam. The authors also report on a Pockels cell shutter arrangement to slice out single subnanosecond pulses.

We have demonstrated a noncontact, fast, and accurate method for ultrasonic measurements in liquids. A pulse laser beam produces an acoustic pulse, whose propagation is monitored by its deflection effects on two cw probe beams. All laser beams are parallel to, but displaced from, one another. The acoustic velocity can be measured to an accuracy of 5 parts in 104 in a measurement time of 100 μs. Temperature‐dependent velocities are measured for ethanol, methanol, water, as well as for concentrated sulfuric acid (which has not been measured previously).

We have developed a new noncontact optoacoustic method for simultaneous measurement of flow velocity and temperature in a flowing fluid to accuracies of 5 cm/s and 0.1 °C, respectively. It is applicable for pure particulate‐free gases and liquids. A pulsed ND‐doped yttrium aluminum garnet (YAG) laser of 40‐mJ energy and 10‐ns duration generates an acoustic pulse whose propagations in directions along and against the flow are monitored by a total of three cw probe beams. We also describe the minimization of errors due to a blast wave (which propagates faster than sound) being generated at the source.

Acoustic propagation velocity v in a fluid depends on flow-velocity v f vectorially and temperature T. Measuring v in two suitable directions provides a good method for determining v f and T simultaneously. This is particularly valuable in gas flows, where the other noncontact flow determination method by light-scattering technique (laser Doppler velocimetry) is difficult because of the negligible Rayleigh scattering efficiencies of gases in the absence of particles (e.g., smoke particles or oil droplets are usually added to the gas to observe light scattering). Furthermore, our noncontact acoustic technique is also applicable to hostile environments (flames, discharges, etc.), where background luminescence may pose severe limitations on light-scattering measurements.

oppler-free two-photon absorption and two-photon dispersion spectra of Rb87 have been taken by FM spectroscopy. Sensitivity achieved is comparable to fluorescence detection. The technique can be readily applied where fluorescence is difficult to detect.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

High frequency wavelength modulation spectroscopy with diode lasers is accomplished by dithering the drive current at RF frequencies between 10 and 250 MHz. This technique is useful for fast and sensitive detection of absorption lines and is applied for fast reading of information from a frequency domain optical memory based upon photochemical hole burning.

Two laser-based techniques, Optoacoustic Laserbeam Deflection (OLD) and Frequency Modu-lation (FM) spectroscopy, were introduced for flame diagnostics. Flame temperature was measured by OLD with 1.5% precision and flame temperature profiles were taken. Ground state and excited state sodium within an aspirated flame were detected by FM-spectroscopy. Present limits of sensitivity are absorptions of 1.5 . 10-4 and ground state sodium densi-ties of 3.3 • 106 cm -3.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We have made new acoustic propagation measurements in vapors and in liquids by a non-contact photoacoustic method. A pulsed laser beam produces an acoustic pulse, whose propagation in the medium studied is monitored by its deflection effect on a CW probe beam. The pulsed excitation beam and the probe beam are parallel to, but displaced from each other. By varying the displacement, the acoustic velocity can be measured. New velocity data on corrosive vapors like Cs metal vapor, and on corrosive liquids like concentrated H2SO4 have been obtained. Accuracies of 5 parts in 104 can be obtained for liquids in a measurement time of 0.1 msec. Hence, the present technique is useful for remote acoustic measurements in hostile environments, with fairly high accuracy so that small changes in the acoustic velocity due to changes in temperature or in chemical composition can be monitored.

We present a study on the magnetic behavior of nanosized iron oxide particles coated with different surfactants (sodium oleate, PVA and starch) in a ferrofluid. The effect of the coating material, and different particle concentrations in the ferrofluid have been magnetically investigated to determine the effective magnetic particle size and possible interaction. The superparamagnetic iron oxide particles, synthesized by a controlled co-precipitation technique, are found to contain magnetite (Fe3O4) as a main phase with a narrow physical particle size distribution between 6 and 8 nm. The mean effective magnetic size of the particles in different ferrofluid systems are estimated to be around 4-5 nm which is smaller than the physical particle size. On a 10% dilution in the starch coated ferrofluid we observe a decrease in the blocking temperature.

Frequency-modulation spectroscopy was employed successfully to measure the Doppler-free absorption and dispersion signals originating from several two-photon transitions in (85)Rb and (87)Rb. The two-photon cross section of the hyperfine transition 5S(1/2) (F = 2) ? 5D(5/2) (F = 4) in (87)Rb was determined to be sigma((2)) asymptotically equal to 4 x 10(-20) cm(4)/W. The transition isotope shift (TIS) of the transition 5S(1/2) ? 5D(5/2) between (87)Rb and (85)Rb was found to be Deltanu(TIS) = +166 +/- 2 MHz.

Photoacoustic-pulse generation by breakdown is achieved in dense cesium metal vapors of vapor pressures ranging from 2 to 130 Torr by using a dye laser pulse of energy variable from 10(-6) to 10(-3) J, tuned to the Cs transition at 6010 A. The acoustic-pulse propagation is detected by the transient photorefractive deflection of a cw probe laser beam that is displaced from but parallel to the pulsed laser beam. The temperature-dependent velocity of infinitesimal ultrasonic waves in a corrosive metal vapor is measured for the first time. The supersonic propagation of finite amplitude acoustic pulses (blast waves) obtained with a higher pulse energy is also studied. Our data, with Mach numbers ranging from 2.1 down to below 1.01, agree surprisingly well with the prediction of Vlases and Jones for cylindrical blast waves. This provides a new experimental support for their theoretical trajectory formula for blast waves in the extremely weak amplitude limit.

Electron‐beam proximity printing (EBP) is a step‐and‐repeat lithography technique which uses masks. Stringent requirement for submicron lithography is the capability to compensate for ever present linear and nonlinear mask distortions. We have demonstrated that a slight modification of the EBP system converts this into a high resolution mask metrology tool, i.e., enabled us to measure absolute distortions of our e‐beam transmission mask in the EBP lithography tool itself. Resolution of these measurements was ±50 nm. Relative mask distortion data as deduced from our results coincided with separate experimental results from overlay experiments.

Electron‐beam proximity printing (EBP) is a promising candidate for submicron lithography because it meets the stringent requirements for resolution, throughput, and image fidelity (here defined as registration and overlay). Registration and level‐to‐level overlay capabilities of EBP are reported in this paper. Two levels of a chip were exposed and processed subsequently, these levels represented by two different patterns in the same mask. Distortions of both patterns relative to each other, amounting up to several hundred nanometers, were detected. These distortions could be automatically compensated for during exposure to yield an average overlay better than 50 nm. Together with the low data scatter of 3σ