Experimental results show that low-fluence UV laser irradiation induces non-thermal photosputtering from surfaces. The photophysical process is the result of surface electronic excitation and energy pooling at particular sites. We present data which show the preferential removal of arsenic from arsenic doped silicon and the role of plasmon excitation in the species desorption from thin metallic films. The observed phenomena has application in nanofabrication technology.

A model to estimate plasma absorption during deposition of thin films has been developed. In this model, the time-dependent plasma dimension is replaced by the time dependent ablation depth which can be determined by numerical simulations. A model to predict the spatial in- homogeneities in the laser-deposited films has also been developed.

To compensate for the loss of Pb during the preparation of BiSrCaCuO films we have deposited layers of PbO as part of a multilayer sandwich structure with BiPbSrCaCuO using the pulsed laser deposition technique. We have carefully optimized three parameters, namely the substrate temperature, post annealing temperature, and post annealing duration in order to produce the highest content of the 2223 phase in the films. By using a substrate temperature of 250 degree(s)C and ex-situ annealing at 854 degree(s)C for 15 hours in air we have produced highly c-axis oriented films which comprises some 95% 2223. These films typically exhibit T_c values of 105.5 K with associated critical current density of 2.5 X 10⁴ A/Cm² at 70 K.

Cd_0.90Mn_0.10Te/CdTe heterostructures grown on CdZnTe substrates by pulsed laser evaporation and epitaxy have been studied by low temperature photoluminescence. The structures were grown from fluxes of Cd-Te and Cd-Mn-Te resulting from the ablation of solid CdTe and Cd_1-xMn_xTe targets with Nd:YAG and excimer XeCl lasers, respectively. The samples chosen for this work are multiple quantum wells (MQW) and superlattices (SL) with buffer and cap layers of various thicknesses and compositions. They have a fixed nominal quantum well width of 2 nm and barriers varying between 4.5 and 16.5 nm, with several combinations of CdTe and Cd_0.90Mn_0.10Te buffer and cap layers.

Various methods for laser-assisted activation of dielectric layers for selective electroless copper plating are investigated. The direct writing of palladium feature by the Ar⁺ laser-induced pyrolytic decomposition of an organometallic palladium resin on polyimide and Si₃N₄ leads to active Pd sites which are selectively copper plated. Other laser-induced processes for selective palladium seeding are studied. It is also shown that those are efficient seeding processes for the electroless plating of copper.

Excimer laser ablation is used as an effective surface cleaning technique for polyimide layers used in electronic packaging applications. Experiments are reported at 193 nm and 248 nm. At each of these wavelengths, ablations of the contaminated polyimide surface were carried out as a function of incident laser fluence. Quantitative determinations of contaminants present in the polyimide were made using surface analytical techniques. It is clearly demonstrated that excimer laser radiation at both 193 and 248 nm can be used to selectively remove trace metal contaminants from polyimide surfaces leaving intact the fine-line metallizations patterned on them. However, differences in the ablation thresholds, as well as in the ablation rates, are observed at these two wavelengths.

The aim of this work was to study the pros and cons of using the laser exposure of thick film screen emulsions (thicknesses 5 - 30 micrometers ) with a mesh count of 200 - 400. A focused Ar⁺ laser, emitting wavelengths in the UV (351 and 365 nm), was utilized in the exposure of commercial negative diazotype emulsions. A special visible sensitized orthochromatic thick film emulsion was used at a wavelength of 488 nm. The Ar⁺ laser beam was focused using an objective with a focal length of 28 mm (UV, apochromatic, NA equals 0.32, spot size 1 micrometers ) and 20 mm (visible, NA equals 0.42, spot size 6 micrometers ). The laser beam was raster scanned with an alignment accuracy of 1 micrometers and unit step of 80 nm and was modulated above the thick film screen.

Progress in the fabrication of continuous-relief micro-optical elements by direct laser writing in photoresist followed by replication into epoxy or polymer materials is described. The technology enables a wide range of micro-optical elements to be fabricated and replicated using Ni shims electroformed from the photoresist originals. Examples of fabricated micro- optical elements are described, including microlens arrays, Fresnel microlenses, kinoforms, and other continuous microrelief phase elements.

We have developed a compact and reliable diode laser-based system for the direct writing of metals from thin organometallic films deposited onto polyimide and SiO₂ substrates. This system uses an AlGaAs diode laser array, emitting at (lambda) equals 796 nm with a maximum power of 1 W. A commercially available gold ink was spin-coated onto the substrate to form the precursor film. Direct writing was achieved by focusing the laser beam onto the film and by moving the substrate at speeds ranging from 10 to 15,000 micrometers /s. We deposited gold lines 2 - 12 micrometers wide onto SiO₂ and 13 - 17 micrometers wide onto polyimide; a thickness of 0.1 micrometers was evaluated by profilometry. Conductive deposits with resistivities of 30 (mu) (Omega) (DOT)cm were obtained on polyimide with good reproducibility at high writing speeds. The selective electroless plating of copper was achieved onto the gold lines deposited on SiO₂. However, prior annealing was necessary to obtain reproducible plating.

The laser microchemical direct-write process is a powerful method to fabricate microstructures required for drawing interconnection networks in customized circuits and remodelling prototype circuits. The laser microchemical direct-write technique is presented by reviewing some laser-induced chemical reactions involved in the deposition of materials used in the microelectronics field. Investigation of the deposition of metals and silicon micrometer-size lines or dots using a cw argon-ion laser operating at wavelengths around 0.5 micrometers , is described. The growth kinetics, morphology and electrical resistivity of the deposits are studied in detail at various scanning speeds of the laser spot, laser beam powers and reactant gas pressures. Investigations of the kinetics of the chemical reactions allow us to propose reaction mechanisms for the decomposition of the reactive molecules used. On the basis of reported results, the use of the laser direct-write process as a tool for restructuring integrated circuits is presented.

We have investigated both the large area excimer laser-induced deposition of W and it silicides on GaAs to form thermally stable Schottky contacts, and the reduction of Cu(I) and Cu(II) compounds for the deposition of Cu interconnects for Si microelectronics. Using a KrF excimer laser at 25 mJ/cm² and a mixture of WF₆, SiH₄ and Ar, metallic W is deposited with an average growth rate of 1 angstrom/pulse. For Cu deposition, the precursor Cu(hfac)(TMVS) gives much purer deposits than the Cu(II) compounds which have been studied. For both processes, possible deposition mechanisms are discussed in terms of gas phase and surface reactions.

A laser processing system is developed for laser microfabrication and micromachining of 3-D microstructures. We show the feasibility of laser induced chlorine etching of silicon under SiO₂ and Si₃N₄ membranes for the formation of underlying cavities and tunnels. Deposition of tungsten and silicon columns on SiO_xN_y/Si substrates is also demonstrated.

This paper presents the recent topics of the laser-beam (LB) writing techniques for fabrication of integrated-optic devices in Ti:LiNbO₃ in addition to the practical LB writing system for channel waveguide patterning in photoresist. Recently, the direct LB writing of TiO₂ channels on LiNbO₃ was demonstrated, providing the photoresist-free process for fabrication of Ti:LiNbO₃ waveguides with higher accuracy and reproducibility. Besides the channel waveguide patterning, the interdigital electrodes required for TE-TM mode conversion in Ti:LiNbO₃ waveguide wavelength filters can be defined with an accuracy of the order of nanometer by a unique LB writing technique that is the so-called LB periodic-dot writing. The writing accuracy is discussed in detail as well as the performance of the fabricated filter.

Basic mechanisms of laser ablation and the most recent results of laser ablation research are discussed here with a focus on semiconductor materials. The pulsed laser evaporation and epitaxy (PLEE) method, which has been developed for epitaxial growth of Cd_1-xMn_xTe (CMT) thin films and CdTe-CMT multiple quantum wells and superlattices, is reviewed. This method of deposition is based on the application of Nd:YAG and XeCl excimer lasers which are exclusively used for the ablation of solid targets: no other vapor generation devices, such as Knudsen cells, are used in PLEE. Microstructures of CdTe- Cd_1-xMn_xTe (0 < x < 0.70) have been grown by the ablation of CdTe, Cd_1-xMn_xTe and Cd targets.

A simple and inexpensive single-step technique for surface patterning in the micrometers regime is presented. As a result of a systematic study on laser-induced ablation and transfer of tungsten thin films it is shown that deposition of well adhering micrometer sized patterns of 100% coverage preserving the shape and dimensions of the laser processed area can be attained by single pulses of peak power up to 100 mW and 100 microsecond(s) - 1 ms duration from a diode laser pumped YAG laser.

The epitaxial growth of LiNbO₃ films by the ArF excimer laser ablation is demonstrated to form electro-optic (EO) thin-film waveguides on sapphire and LiTaO₃ c-plates. The x- ray diffraction spectra indicate that the resulting films are well oriented along the c axis when a Li-rich LiNbO₃ ceramics is used as the target. The chemical composition of the film was successfully evaluated by measurement of the extraordinary index n_e on the basis of the guided-wave excitation with prism couplers. Stoichiometric films are grown on both sapphire and LiTaO₃ c-plates by changing the content of excess Li₂O in the target. The propagation loss of 6 dB/cm was attained in the thin-film waveguide on LiTaO₃ c- plate. In addition, the EO effect of the film was roughly estimated by fabrication and characterization of a light deflector with an EO grating.

Waveguide excimer lasers in combination with high-resolution imaging and precision motion control systems are capable of direct-write shaping of many polymers, ceramics, glasses, and metal films. Three-dimensional structures can be produced by scanning the worksurface under the focused beam and varying the energy delivered to the worksurface through use of various exposure algorithms. Using this technique, we have produced 3-D structures in polyimide and diamond that demonstrate high spatial resolution and good surface finish.

The metal and semiconductor films (MSF), deposited on the glass and metal substrates, have been used as recording materials when fabricating diffraction gratings by pulse laser irradiation of 1.06 micrometers . The processes of photothermal ablation are the basis for mechanism of diffraction structure formation. The gratings at spatial frequencies of 100 and 500 mm^-1 have been fabricated without postexposure treatment by pulse laser irradiation of 20, 100 and 1000 ns in duration. It has been shown that dependence of threshold energy density E_thr from pulse duration (tau) is well approximated by function E_thrvaries direct as(root)(tau) . The relief-phase component of the grating's diffraction efficiency (DE) has been measured.

Silicon oxide, oxynitride and nitride films are deposited at low temperature (<EQ 450 degree(s)C) by pulsed ArF excimer laser ablation from silicon, silicon monoxide, fused silica and silicon nitride targets, performed under vacuum and in oxygen atmosphere. We investigate in this paper the specific influence of laser fluence, target materials, substrate temperature and oxygen pressure on the composition and final properties of SiO_xN_y grown layers. The process conditions are optimized in order to deposit good quality silicon oxide and silicon nitride thin films.

As a `cold process' photochemical deposition enables us to obtain insulator and dielectric thin films on III-V compounds. To sustain the remarkable progress in the performance of electronic and optical devices may necessitate the utilization of this innocuous processing for novel applications. Possible areas of interest range from simply optically protective coating to layers for highly sophisticated optoelectronic integration of III-V and Si on the same chip.

We report the use of vacuum ultraviolet (VUV) light generated from a new type of excimer lamp to initiate the deposition of dielectric thin films in a photo-chemical vapor deposition process. Compared with other lamps, these pseudo-continuous light sources can provide high photon fluxes (more than a few watts) over large areas. The photo-deposited film properties were determined using the usual techniques of ellipsometry, FTIR spectroscopy, and electrical measurements. Good film quality was obtained making this technique highly attractive. A layered combination of silicon oxide, silicon nitride, and silicon oxynitride can be produced in the same reactor at temperatures below 300 degree(s)C. The technique also offers very good control of the stoichiometry in the case of Silicon oxynitride film deposition, and therefore provides interesting perspectives for optical applications.

Applications of KrF excimer laser for processing of polycrystalline diamond films and hard amorphous (`diamond-like') carbon films grown by chemical vapor deposition are reported. A technique of selective-area deposition of diamond films on Si substrates is described. Smoothing of rough surface of as-grown films using a scanning laser beam, and high speed drilling of diamond films were realized. Laser etching of amorphous carbon in air is shown to occur by two mechanisms: (carbon oxidation, which provides etch rates of a few nm/pulse, and (2) physical ablation dominating at high fluences. Micron-sized patterns were produced in amorphous films using the `mild' laser-chemical etching regime without any damage of Si substrates. It is concluded that lasers are very efficient tools for patterning, polishing, and shaping of these two classes of the extremely hard and chemically inert materials.

Laser holography is a very promising technique for HTS thin film patterning. It gives us the possibility to produce the whole picture on a film by one laser pulse. By using this technique we fabricated an 8-turn spiral coil with 10 mkm linewidth. In the case of front side interaction the laser beam caused modification (transformation to nonsuperconducting state) of the irradiated parts of the film, in the case of backside interaction the laser beam passed through a transparent substrate and caused accurate removal of the irradiated parts of the film. Our calculations show that the temperature which arises in the film at these energy densities is significantly below the melting temperature of YBCO material. Possible mechanisms of this backside removal are discussed.

Application of the laser direct writing technique for maskless fabrication of micro-optic components is discussed. Parameters characterizing the laser writing by poly-Si deposition on various substrates and by crystalline Si etching are given. Dimensions of the fabricated features and their topography are described. Results obtained by combining the laser writing with other techniques, such as the blanket deposition of phosphosilicate glass and spin-on glass, and isotropic silicon etching in HF/HNO₃ solutions, are presented. Examples of the fabricated microlenses and microgratings are shown.

We report the synthesis of iron silicide layers by multipulse excimer (XeCl) laser irradiation of Si/Fe bilayers (50 and 90 nm thick, respectively) deposited on single crystal silicon wafers. A mixture of iron silicide phases is usually formed after a few hundreds of laser pulses at the fluence of 0.5 J/cm² with a repetition rate of 50 Hz. After thousand pulses the high- temperature stable (alpha) -FeSi₂ silicide forms.

A fiber-optic temperature sensor has been fabricated by sputtering a silicon film, together with some protective overlayers, directly onto the end of an optical fiber. The approximately one- micrometers thick silicon film serves as a Fabry-Perot etalon whose resonant wavelengths vary as functions of temperature due to changes in the film's refractive index. To manufacture a sensor with adequate long-term stability, the initially amorphous silicon film must be annealed. Laser annealing has been found to be a promising means to stabilize the silicon film's structure without degrading the optical fiber's protective buffer coating.

Fine lines of (alpha) -Fe₂O₃ have been formed on quartz substrates by laser beam direct writing on metalorganic (MO) spin-coated films. A modulated krypton ion writing laser beam and a He-Ne probing laser beam were colinearly focused onto the films with a spot size about 10 - 50 micrometers . A series of characterizations were conducted on the written lines by employing characterization techniques ranging from TGA, FTIR, SEM, XRD, to TEM. In this way a better understanding has been achieved regarding the metalorganic decomposition mechanism, structure and morphology of the laser written lines. From the time-resolved transmittance change induced by the krypton ion laser pulse irradiation, transient behavior of laser decomposition process of metalorganic materials has been studied.

A top-drive variable capacitance (VC) electrostatic rotational micromotor with double stator was fabricated combining bulk silicon machining with etch stop on junction to anodic bonding of silicon to glass. The novel process overcomes the drawbacks found in the fabrication of top- drive devices by use of usual surface micromachining of polysilicon LPCVD layers.

The paper presents the process planning and scheduling of two types of micromachined capacitive transducers for pressure measurements. The fabrication process includes micromachined silicon and glass components. The different stages, process parameters and the required time to obtain devices with flat and corrugated membranes, are presented. The information generated from a laboratory scale experiment is extended to an industrial system. A process that involves the manufacturing of 4,800 devices once on 100 three-layer sandwich structures is studied. A total of 47 activities and 9 alternate operations are identified. For each of them, the time period is established using the acquired experience of the laboratory process. All the techniques and their parameters, the resources are screened and the time necessary to accomplish the above mentioned devices, starting from the si and glass wafers are determined. The activities are considered according to their priorities and two process networks are considered for the two types of devices for flat plate and for corrugated plate. The critical activities and the necessary resources at each step are established. An optimum activities' scheduling for the processes is proposed, in which the priorities and the critical processes are identified. The resource allocations and their capacity are also determined.

This paper presents evidence of the influence of the state of stress on anisotropic etching of (100) oriented Si in KOH water solution. External load is applied to strips of Si which modifies the initial internal stress state actually generated by a patterned SiO₂ masking film. Results obtained for circular patterns indicate that the etch patterns on the strips subjected to negative and positive stresses are different from each other and are different from strips which have not been subjected to external loads. These observations indicate that the etching process is influenced by the presence of stresses in the silicon. A technique to analyze the stress is proposed. The resulting variations of etched features with applied stress is significant.

In this paper, a new type of sound-optical array of microvibrator sensor which detect speech features in frequency domain and the fabrication process of the microvibrator is presented. The technique of detection by optical fiber and speech recognition in noise using neural networks (NNs) has been described. The results of experiments show that the sensor based on the new idea is suitable for an optical sensor, especially for the speech recognition system with optic-machinery unitization for it changes the sound signal into an optical signal, at the same time it carries out parallel filters spectrum analysis to obtain directly sound spectrum features which can be used as input of the NNs.

This paper presents an extrinsic Mach-Zehnder type accelerometer which utilizes a gap between a fiber cantilever and a fixed fiber. The problem of light insertion to the single mode fiber across the gap is eased with the use of quarter pitch GRIN lenses. Phase feedback is done through the laser diode in conjunction with active homodyne demodulation. The accelerometer has a dynamic range of 84 dB and a resolution of 10^-4 g. The configuration uses all-fiber components which is readily transferable to the integrated-optic domain.

A miniature Fabry-Perot cavity consists of a 10 micron deep by 5 micron wide slit which is formed in a silica (SiO₂) waveguide over silicon with the use of reactive ion etching. The multiple beam interference is due to successive reflections from both walls of the slit. The reflectance close to the critical angle exhibits a finesse over 20. A model is developed to simulate the loss due to scattering from the etched wall roughness. The loss in amplitude is only 7% after each reflection. Thus, the etched walls are vertical and smooth and can be used as efficient mirrors in integrated-optical circuits and interferometers.

Micromechanical processing tools fall into three basic categories: bulk micromachining of single crystal materials, surface micromachining with deposited films and lateral sacrificial etching, and high aspect ratio processing of polymers and metals. The third category includes LIGA and LIGA-like processing which shares with high aspect ratio processing the need for thick polymer layers with good chemical behavior, acceptable mechanical properties and minimal built-in strain. A decal technique via solvent bonding of thick, essentially strain free polymethyl methacrylate sheets has been used as an alternative to casting and in situ polymerization to avoid the strain difficulty. Final photoresist thicknesses between 100 to 500 micrometers are achieved by precision mechanical milling, prior to x-ray exposure. The photoresist process has been used to produce structures with structural heights to 500 micrometers and run-outs of less than 0.1 micrometers per 100 micrometers of structural height in a LIGA-like processing sequence which combines the LIGA process concept with surface micromachining.

In this paper we discuss methods for fabricating high aspect ratio structures in thick photoresist. Resist thicknesses in excess of 10 microns can be patterned with near-micron features and with near vertical sidewalls using the techniques described herein. Limits of the lithography relating to dimension control and to maximum usable resist thickness are discussed. Applications of the process to optoelectronics and micromachining are described.

Repeated conventional UV depth lithography and electroplating allows us to produce microstructures of varying size in the third dimension. The structures are about 50 micrometers high and the bearing clearances are in the micrometers range. A number of alternative processes and applications are reviewed. The status of the UV depth lithography of positive photoresist and the TUB process for electroplating (Au) high depth-to-width aspect ratio microstructures is briefly described. Capacitive micromotors, a capacitive acceleration sensor, and 3D microcoils have been fabricated. These results are discussed and possible future steps and applications are mentioned.

Louisiana State University established the J. Bennett Johnston, Sr., Center for Advanced Microstructures and Devices (CAMD). Designed and constructed by the Brobeck Division of Maxwell Laboratories, the CAMD synchrotron light source is the first electron storage ring to be built by a commercial company in the United States. The synchrotron x-ray radiation generated at CAMD is an extremely useful exposure source for both thin and thick film lithography. Passing through a beamline containing two plane mirrors, the synchrotron light is used to expose thin resists for lithography of patterns with feature sizes of 0.25 micron and smaller. Two thick-resist beamlines, one using a single aspheric (collimating) mirror and one using a plane mirror, provide the higher flux photons required for miniaturization in silicon to produce microscopic mechanical devices including gears, motors, filters, and valves.

Excimer laser ablation is an excellent means of depositing high temperature superconducting (HTS) thin films because of high quality electrical properties of the resulting films and also because of the relative simplicity of the deposition system. The principal disadvantage of laser ablation is the contamination of the deposited film by particles, leading to a rough film surface. The influence of substrate temperature on surface morphology in YBa₂Cu₃O₇ thin films deposited by excimer laser on r-plane sapphire with a CeO₂ buffer layer has been investigated. The substrate temperature was measured using gold-nickel thermocouples on the substrate surface during deposition. The optimal deposition temperatures were found to be lower in comparison with films deposited on LaAlO₃ because damage occurs to the buffer layer. Special attention was paid to the occurrence of droplets and outgrowths in the films. The ablation process produces droplets that range from 0.1 micrometers to a maximum of 1 micrometers in size. In the course of film growth these droplets undergo metamorphosis and form the basis of outgrowths.

Variation of the ultrasonic frequency of an acousto-optical modulator produces a tunable grating. For a fixed deflection angle the wavelength of the diffracted light changes. A tuning of operation mode related to the geometrical dimensions is necessary.