The interaction of nanosecond ultraviolet laser light with bulk optical materials is discussed for the example of fluoride crystals. Absorption and thermoelastic response of the crystals are related to the laser damage threshold. It is shown that this threshold is most limited by defects resulting from surface preparation. Cleavage of crystals produces atomically flat terraces with highest damage thresholds (> 40 J/cm² for ns-pulses at 248 nm) while cleavage steps and tips result in a dramatic local reduction of damage resistivity. Conventional polishing introduces contamination, scratches and dislocations yielding damage thresholds of typically 10 to 15 J/cm². Advanced preparation techniques like chemo-mechanical polishing and precision grinding provide surfaces with a damage threshold uniform over large areas that is close to that of cleavage terraces. In all cases the damage threshold is determined by light absorption of defect-induced electronic states energetically located in the band gap of the insulator. Band gap states in calciumdifluoride are investigated by ultraviolet photoelectron spectroscopy and luminescence spectroscopy and surface quality is monitored by scanning electron and scanning force microscopy. Laser damage thresholds obtained for differently prepared surfaces are related to their structural and electronic properties and the primary mechanisms of energy uptake from the laser light are discussed.

As a result of rapid engineering progress, femtosecond lasers will soon be available for industrial applications such as micro machining. I will review the physics behind laser machining of metals, semiconductors and transparent materials. Then I will briefly discuss the current state-of- the-art in femtosecond laser technology of interest to micro machining.

A new theoretical model describing laser hole drilling processes for polymers and fiber reinforced composites has been developed. The model can explain the tapered wall formation and the stabilized hole formation. This model can predict the hole shapes for certain incident beam profiles. We present two specific incident beam shapes, one for a Gaussian incident beam, and the other for an isosceles trapezoid shape beam. For the Gaussian incident beam, we show how the peak fluence, the beam diameter, and the material parameters (absorption coefficient, threshold ablation fluence) affect the hole shapes. For the trapezoid shape beam, we show how the flat top of the beam, the side slope wings, the peak fluence, the threshold fluence and the absorption coefficient affect the hole shapes.

In-situ atomic absorption spectroscopy with diode lasers has been performed for monitoring and study of the deposition process in electron beam evaporation. The combination of the wavelength-modulation spectroscopy with external-cavity diode lasers and the balanced detection scheme guarantees the high sensitivity and reliability of the system. Direct measurements of atomic flux in e-beam evaporated yttrium and barium, which are components in YBCO superconducting thin films, have been demonstrated. Atomic number density and velocity were measured through absorption and Doppler shift measurements, respectively, to monitor the atomic flux. The measured velocities show that the e-beam evaporated atoms are in a non-thermal equilibrium state, dependent on source conditions, implying that the flux measurement rather than a simple density measurement for rate control is necessary. Comparison with quartz crystal monitors shows that the present scheme, employing two laser beams counterpropagating at an angle to the substrate surface for measuring the velocity component normal to the substrate surface, can provide a pressure-independent flux measurement. In yttrium, which has an additional significantly populated metastable level, results show that pressure-independent flux measurement requires measurements at both the ground state and the metastable levels. Real-time curve-fitting for in- situ flux measurement was demonstrated. In addition, sticking and re-evaporation characteristics of barium was also investigated, demonstrating the feasibility of in-situ sticking coefficient measurement.

The results of a study of the laser Photon Stimulated Desorption (PSD) from an oxidized tungsten surface using 248 nm light are reported. The tungsten oxide system was chosen as a prototype for stimulated desorption resulting from the laser interaction with an oxide covered metal surface. The desorption yield, laser fluence dependence, and behavior of tungsten, tungsten oxide and other desorbed cations (including alkali atoms) have been used to probe aspects of the energetics under different conditions of oxygen dosage and laser exposure history. It is interesting to compare the nonlinear laser PSD results with the Electron Stimulated Desorption results which have appeared in the literature.

Laser annealing of a-Si to form p-Si LCD panels requires precise control of the annealing beam shape and scan overlap. Three methods are presented for determining the annealed quality of a-Si LCD panels. The first tests the laser beam directly by using polymer coated 8 X 10 inch SensorCards. The second allows live viewing of the beam in real time with a fluorescent glass. The third looks directly at the optical properties of the annealed a-Si to infer eventual electrical properties.

Microprocessing and film deposition with laser radiation of short wavelength and pulse length are investigated to present their process capabilities for the manufacturing of surface structures and layers within precision ceramic (BaTiO₃, Si₃N₄, SiC) components. The microprocessing with fundamental (1(omega) ) and higher harmonic (2(omega) , 3(omega) ) Nd:YAG laser radiation (ns- and ps-pulses) is performed yielding structural dimensions below 20 micrometers during drilling and caving with the results related to the removal threshold fluence and the removal rate per pulse. The film deposition with excimer laser radiation ((lambda) _L equals 248 nm, (tau) _L equals 20 ns) achieves monolayer thin films of different properties according to the laser parameters and processing variables with the results related to deposit multilayer film systems. The properties of the structures and of the films are analyzed by profilometry, optical and electrical microscopy, as well as X-ray photoelectron spectroscopy. Examples are highlighted for various ceramics and discussed in view of applications of the structures and films generated.

Novel ablation of wide band gap materials such as fused quartz by multiwavelength excitation using a VUV-UV laser system is reviewed. Simultaneous irradiation of VUV and UV laser beams emitted from a VUV Raman laser presents great potential for precise microfabrication of the materials. The mechanism and the role of VUV beams in this process are made clear on the basis of band structure. Furthermore, the advantages of this technique are discussed in comparison with the conventional single wavelength ablation. This technique is applied to selected area removal of SiO₂ films on Al lines for repair of Si integrated circuits.

We report on the generation and potential applications of an UV light source tunable from 280 nm to 315 nm with an average power of more than 0.5 W and high absolute conversion efficiency. Overall conversion from the diode pumped Nd:YAG laser fundamental (1064 micrometers ) wavelength to the tunable output exceeded 6%, and an absolute efficiency of Ce:LiCaF laser to the 266 nm pump was in excess of 27%. The diode pumped Nd:YAG laser used in the experiments delivered 1.9 W of average power at 266 nm by successive doubling and quadrupling of 8 W output at 1064 mum. The advantage of using 1 kHz pulsed-diode pumped Nd:YAG laser source lies in relatively high energy per pulse, as compared to the systems with continuous diode pumping, thus allowing high conversion efficiency into fourth harmonic. The fourth harmonic output beam was slightly focused into a 5 mm long Ce(2at.%):LiCaF crystal with AR coated faces. The relatively large energy of the pump pulses resulted in a large beam cross-section in the crystal, thus allowing efficient quasicollinear longitudinal pumping. The laser was tunable from 280 nm to 315 nm. The output linewidth varied from 0.3 to 0.6 nm, depending on spectral position and the pump power. Applications in microelectronic and optoelectronic manufacturing will be discussed.

The continuing trend towards miniaturization of integrated circuits requires increasing efforts and new concepts to clean wafer surfaces from dust particles. We report here about our studies of the `steam laser cleaning' process first described by Tam and coworkers. In order to remove submicron particles from a surface, first a thin liquid layer is condensed onto the substrate from the gas phase, and is subsequently evaporated momentarily by irradiating the surface with a short laser pulse. We have investigated the nucleation and growth of gas bubbles in the liquid, by which the whole process is started, with optical techniques like light scattering and surface plasmon resonance spectroscopy. The experiments indicate that the temperature where nucleation sets in is surprisingly low, which facilitates the application of this phenomenon for cleaning purposes. On the basis of these results and in order to study the cleaning effect for the particularly interesting surface of silicon in a quantitative way, we have deposited well-characterized spherical polymer and silica particles of different diameters from several ten to hundred nanometers on commercial Si wafers and have studied systematically the cleaning efficiency of the explosive evaporation process. The results show that steam laser cleaning is a promising and suitable method for removing sub-micron particles from semiconductor surfaces.

Integrated circuits complexity is controlled by defective sections which decrease IC yields and limit chip area to a few sq. cm. The post fabrication laser processing techniques of cutting lines and forming connections are effective in removing defects and enhancing fault tolerance in large VLSI circuits. Successful applications require designs which include redundant sections for substitution and the defect avoidance points built into the structure. Commercial devices have used cutting polysilicon lines to substitute rows and column blocks in memory chips (DRAM's), microprocessor's cache memory and Field Programmable Gate Arrays. More complex wafer scale systems of 25 sq cm have been built using combinations of additive connections and line cutting to route signals around defective areas thus creating defect free large working systems. These used laser diffused links consisting of two conductively doped lines in silicon separated by a gap. An argon ion laser pulse (100 microsec., 2 W, 1.2 micron FWHM) spreads dopant throughout the gap generating approximately 70 ohms connections. Metal links of two metal lines, separated by 1 micron), covered by intermetal insulator. A laser pulse expands the metal, fractures the SiO₂ between the lines, and forces molten metal to make < 3 ohms connections. Both links show lower impedance alternative like active transistor switches (approximately 3 - 6 Kohm).

Removal of foreign materials formed during VLSI/ULSI processing, is one of the challenges of advanced semiconductor technology. As device geometries continue to shrink, microcontaminants such as particles, metallic contaminants, photoresists and other organic residues have an increasing impact on yield. As wafer processing becomes more aggressive and contaminants which are yield limiting become much smaller, traditional cleaning techniques based on wet-chemistry cleaning become less adequate. Only a completely dry cleaning process can overcome all the drawbacks associated with the problematic wet chemistry cleaning. A novel DUV-Excimer laser Dry removal method allows the elimination of these contaminants, in a single step process.

A photon flux from a laser can provide an alternative method to clean and prepare industrial surfaces. The laser-based cleaning method presented in this paper uses only photons coupled with a laminar, flowing gas which is inert to the surface. This method can eliminate or reduce the water and chemical volumes used in industrial applications. In this paper, the development issues bringing a technology into the mainstream are discussed.

Novel single block process facility including UV excilamp and sources of atomic hydrogen is described. Circular sealed-off KrCl* excilamp emitting two intensive bands at 195 and 222 nm was used. The source of atomic hydrogen on the base of reflecting Penning arc discharge was placed in line with the lamp. Semiconducting structures were treated in an expanding effusion jet of atomic hydrogen. The possibility to realize the process of cleaning GaAs surface under joint action of atomic hydrogen and UV radiation has been investigated. Effect of UV radiation on the rate of removing oxide layer is found at low temperature (18 - 100 degree(s)C). The mechanism providing an explanation for this event is suggested. The possibility to realize GaAs surface cleaning using successive performing the procedures of the surface treatment by atomic hydrogen, its oxidation with UV- stimulation and additional treatment by atomic hydrogen was also studied. The sources of atomic hydrogen and UV radiation developed allows to improve cleaning control and provides a way of producing the surface with specified properties.

The dry etching of Si with XeF₂ and of GaAs with Cl₂ in a wavelength range around 120 nm combines very high efficiency with excellent selectivity and provides a perspective to reach lateral resolutions required in about 10 years. Projection optics based on conventional optical materials and light sources seem to be feasible. The high quantum efficiencies between 10 and 100 removed atoms per photon originate from chain reactions. The relevant reactions are initiated by excitation of surface layers which provides the high selectivity. Optimal etching conditions concerning dark reaction and nonselective reactions are specified. The influence of the chain reactions on the topography is investigated.

The chemical composition and surface morphology of (001) InP wafers, selectively etched in a chlorine atmosphere in the presence of UV laser illumination, was studied. The etching was carried out in a low pressure mixture of chlorine and helium (10% Cl₂/He). For etching to take place, the surfaces were exposed to 308 nm pulsed XeCl excimer laser radiation with the fluence well below the ablation threshold of InP. The x-ray photoemission spectroscopy investigations indicate that, at room temperature, the applied etch mixture does not spontaneously react with the InP wafers. Laser irradiation at a fluence less than the ablation threshold of InP stimulates a chemical reaction. At low fluence, no In-Cl compound remains on the wafer surface after the process. In the illuminated areas, the presence of In-P-O and P-O is observed at larger amount than in the non-illuminated areas. Scanning electron microscopy studies show that laser illumination results in the efficient removal of reaction products from the illuminated area. The small scale morphological structures observed on the surface depend on the total amount of exposure to laser radiation.

The surface chemical modification of polyurethane (PU) films was performed by a UV laser-induced chemical reaction in a polysaccharide solution. This was undertaken with the possible application of hydrophilic packaging of implantable medical devices and in-vivo sensors. When a PU film in an aqueous alginic acid (AAC) solution was irradiated with the XeCl laser, it turned hydrophilic. Contact angles of water on the film were changed from 110 degree(s) to 60 degree(s). Since the absorption of AAC solution at 308 nm was negligibly small, the laser irradiation produced reactive sites solely on the PU surface, where AAC could be immobilized by chemical bonds. The mechanism for the modification was investigated by surface analyses with Fourier transform infrared spectroscopy and a photometric dye staining technique. This hydrophilic modification was interpreted as nanometer-scaled grafting of AAC induced by one-photon photochemical processes.

This work investigates deformation of stainless steel and ceramic specimens with a precision on the order of submicrometers by use of a pulsed laser beam as the energy source. Such a technique is useful, for example, in a process of removing distortions on magnetic head components for a better contact between the magnetic disk head and the hard disk surface. Experiments are conducted to study the bending behavior of stainless steel and ceramics due to laser irradiation. A pulsed Nd:YLF laser beam is used to scan over the specimen to create out-of-plane deformation. The amount of deformation from each laser scan is correlated with various laser and processing parameters. A theoretical model of the laser deformation process is presented based on thermo-elasticity/plasticity. The laser deformation process is explained as a result of the laser-induced non-uniform distribution of the residual strain. Numerical simulations are carried out to estimate the laser-induced temperature field, the residual stress field, and the amount of deformation of the specimen. These theoretical studies help to understand the complex phenomena involved in the pulsed laser deformation process.

Optical transmission and reflectivity of ceramics and CVD diamond plates prior, in the process and after ablation by intensive nano- and picosecond pulses of Nd:YAG and Nd:YAP lasers are investigated. Laser induced surface layer modification effects and plasma influence are considered. Correlation between crater depth and plasma optical properties was found. The mechanisms of crater walls influence on plasma are discussed.

Semiconductor laser diodes, while not yet ready to replace YAG and CO₂ lasers from heavy duty machining, are already capable of carrying out a number of manufacturing jobs that require a power density of 100 kw/cm² or less, and CW power of 100 Watt or less. We present results of cutting cellulose materials, marking plastics, soldering electronic circuit boards, surface (transformation) hardening, chemical vapor phase deposition (by gas breakdown) using fiber coupled CW lasers at 810 nm (60 Watts) and 980 nm (25 Watts). We also present the results of sintering metal powders under different conditions to improve density and hardness, demonstrating that diodes can do an excellent job in solid free-form development (or rapid prototyping).

This paper explores the wide range of laser micromachining applications used in contract manufacturing. Contract manufacturing is used in several key industries such as microelectronics packaging, semiconductor, data storage, medical devices, communications, peripherals, automobiles and aerospace. Material types includes plastics, metals, ceramics, inorganics and composites. However laser micromachining is just one available technology for micromachining and other methods will be reviewed. Contract manufacturing offers two important glimpses of the future. Firstly prototype work for new applications often beings in contract manufacturing. Secondly, contract manufacturing can be an economic springboard to allow laser systems to be installed in a production environment.

Excimer lasers are the third major classification of industrial laser in use today (the first being CO₂ lasers and the second being solid state lasers, such as YAG). Excimer lasers are used with far field mask image projection techniques, and as such are potentially inefficient due to UV photons being lost at the mask. Cost effective materials processing requires that the maximum amount of available UV photons are efficiently utilized. This paper outlines some of the latest excimer laser beam delivery techniques currently used for high volume micromachining and via drilling production applications. UV solid state lasers are increasing in average power and beam quality but are still limited to a few watts of average power. New mask illumination techniques can improve production throughputs by factors of 2X to >10X over conventional excimer mask projection processing. This paper discusses methods currently available applying the high average power of 50 to 100 watts available with increasing cost effectiveness.

Multilevel microelectrode structures have been produced using excimer laser ablation techniques to obtain devices for the electro-manipulation of bioparticles using traveling electric field dielectrophoresis effects. The system used to make these devices operates with a krypton fluoride excimer laser at a wavelength of 248 nm and with a repetition rate of 100 Hz. The laser illuminates a chrome-on-quartz mask which contains the patterns for the particular electrode structure being made. The mask is imaged by a high- resolution lens onto the sample. Large areas of the mask pattern are transferred to the sample by using synchronized scanning of the mask and workpiece with sub-micron precision. Electrode structures with typical sizes of approximately 10 micrometers are produced and a multi-level device is built up by ablation of electrode patterns and layered insulators. To produce a traveling electric field suitable for the manipulation of bioparticles, a linear array of 10 micrometers by 200 micrometers microelectrodes, placed at 20 micrometers intervals, is used. The electric field is created by energizing each electrode with a sinusoidal voltage 90 degree(s) out of phase with that applied to the adjacent electrode. On exposure to the traveling electric field, bioparticles become electrically polarized and experience a linear force and so move along the length of the linear electrode array. The speed and direction of the particles is controlled by the magnitude and frequency of the energizing signals. Such electromanipulation devices have potential uses in a wide range of biotechnological diagnostic and processing applications. Details of the overall laser projection system are presented together with data on the devices which have been manufactured so far.

The advent of sealed CO₂ lasers has significantly increased industrial laser applications during the last 5 years. The main advantages of this type of laser are the compact footprint, robust all-metal construction, no maintenance and low operating costs. The applications of sealed CO₂ lasers in the microelectronics industry can be broadly classified into four major categories: Ceramic Processing for Thick/Thin Films, Printed Circuit Boards and Flex Circuit Board Drilling and Routing, Solder Mask Cutting for SMT and Microwelding for the packaging industry. This paper summarizes potential applications for sealed CO₂ lasers in the microelectronics industry. Detailed process capability with speeds and thicknesses will be presented and comparisons will be made to other laser and conventional fabrication techniques.

During the last decade laser processing of polymers has become an important field of applied and fundamental research. One of the most promising proposal, to use laser ablation as dry etching technique in photolithography, has not yet become an industrial application. Many disadvantages of laser ablation, compared to conventional photolithography, are the result of the use of standard polymers. These polymers are designed for totally different applications, but are compared to the highly specialized photoresist. A new approach to laser polymer ablation will be described; the development of polymers, specially designed for high resolution laser ablation. These polymers have photolabile groups in the polymer backbone, which decompose upon laser irradiation or standard polymers are modified for ablation at a specific irradiation wavelength. The absorption maximum can be tailored for specific laser emission lines, e.g. 351, 308 and 248 nm lines of excimer lasers. We will show that with this approach many problems associated with the application of laser ablation for photolithography can be solved. The mechanism of ablation for these photopolymers is photochemical, whereas for most of the standard polymers this mechanism is photothermal. The photochemical decomposition mechanism results in high resolution ablation with no thermal damage at the edges of the etched structures. In addition there are not redeposited ablation products or surface modifications of the polymer after ablation.

Machining of reliefs is a fairly new laser application and on the verge of industrial usage. The main problem is that the surface quality degrades with increasing ablation rate. Experiments and simulations are carried out to improve the process. It will be shown that fine structures and excellent surface qualities can be achieved with CO₂ lasers. For rapid tooling a complex 3D relief for embossing and stamping applications will be presented. The machining process of reliefs in steel is described by a mathematical model. The ablation geometry is calculated analytically by the temperature field due to pulsed laser radiation. As working gas a mixture of oxygen and nitrogen is used. The oxidation process plays a vital role in the laser ablation process and will be discussed in more detail. The molten film of oxidized and non-oxidized material at the ablation front is described as a stationary boundary layer flow. The thickness of the oxidized layer determined the ablation process significantly, e.g. absorption increases with an oxidized layer rapidly. To determine the absorption of the laser radiation, the interferences between the oxidized and the non-oxidized melt films are investigated. A comparison between the calculated and the machined ablation geometry shows a good correspondence for mild steel.

Projection photolithography is widely expected to remain the main high-throughput patterning technology of microelectronic circuits in the next few years. As the critical dimensions of these devices shrink to 0.18 micrometers and below, the lithographic wavelength will decrease from 248 to 193 nm, and possible to 157 nm. This paper reviews the challenges posed by reducing the wavelength to below 200 nm, and the current state of the art in the critical areas of optical materials, photoresists, and high-resolution patterning.

As polymers tailored for laser ablation at a specific wavelength usually require a costly synthesis that makes them expensive, standard materials are investigated in the present study that are already produced on a large scale. Apart from an absorption band around the laser wavelength (here, 308 nm) further properties are important in technical applications, such as thermal and photochemical stability or optical transparency. High etching rates combined with high quality structuring are required for photon-efficient ablation. Depending on these criteria we chose several standard materials, which are commercially available, and characterized the ablation behavior. The substrates include polymers such as polycarbonates, polymer blends, and in addition glassy carbon substrates, which are wide-spread in industrial appliances already and promising for devices fabricated by excimer ablation lithography. The characteristic parameters were determined and the quality of the obtained structure was investigated by scanning-electron- and atomic-force-microscopy. Examples of applications in microtechnology will be shown.

Differences between EAL and the conventional photolithography are mainly with respect to the resist materials and the mask. The mask consists of dielectric multilayer reflector, and the thickness and the structure are completely different from Cr masks. This paper is aimed to clarify the influences of dielectric mask to the image qualities, and presents a rigorous simulation of the diffraction by the dielectric mask and preliminary experimental results. These results show that for low N.A. imaging system, there are not substantial differences between the dielectric mask and the metal mask concerning the resolution power, however further investigations are required for the interpretation of rather wide resist edge corresponding to a straight edge of the large opening mask.

This paper describes the studies on nanoparticle synthesis process by the laser ablation in a background gas and the metal film deposition by the laser-induced forward transfer (LIFT) technique. In order to understand and control the processes, an imaging diagnostic system has been developed. Firstly, the behavior of nanoparticles in a laser ablation plume was studied with the imaging system. The attempt to control the nanoparticle behavior was examined. Next, the metal film deposition by the LIFT technique was studied with the different laser-pulse duration from 160 fs to 60 ms. The results are reported along with the imaging observation of the LIFT process.

A novel polymer processing technique, matrix assisted pulsed laser evaporation (MAPLE), for the deposition of organic and inorganic polymers and other materials, as ultrathin and uniform coatings has been developed. The technique involves directing a pulsed excimer laser beam onto a frozen matrix target composed of the polymeric material in a solvent. The process gently lifts polymeric material into the gas phase with no apparent decomposition. A plume of material is developed normal to the target, and a substrate positioned incident to this plume is coated with the polymer. The MAPLE technique offers a number of features that are difficult to achieve with other polymer coating techniques, including: nano-meter to micron thickness range, sub monolayer thickness precision, high uniformity, applicability to photosensitive materials, and patterning of surfaces. Highly functionalized polysiloxanes have been synthesized and deposited on a range of substrates by the MAPLE technique and characterized by: infrared spectroscopy, and optical microscopy. High quality, uniform and adherent polysiloxane coatings are produced by the optimized MAPLE technique. The physicochemical properties of the coating are unaffected by the process, and precise thickness control of the coating is straightforward.

Thin films of 4-cyano-4'-pentylbiphenyl (5CB) and E7 liquid crystals have been fabricated by pulsed laser deposition. The suitability of different lasers (ArF, KrF, XeCl and CO₂) has been investigated over a range of fluence using visible-UV and infrared absorption and optical polarizing microscopy to characterize the films. High performance liquid chromatography and matrix assisted laser desorption ionization mass spectroscopy were used to assess the extent of decomposition of the films. The high photon energy of ArF and KrF excimer lasers produce severe and partial decomposition of the deposited films respectively, whilst films deposited using the CO₂ laser also present partial degradation, most likely related to thermal processes during the laser-target interaction. Films with near identical structure to that of the starting LC target and good textures were obtained by XeCl laser deposition up to fluences of 130 mJ/cm².

Low loss ferroelectric thin films deposited by pulsed laser deposition (PLD) are currently being used to develop a new class of tunable microwave circuits based on the electric field dependence of the dielectric constant. Single phase, (100) oriented Ba_0.5Sr_0.5TiO₃ (BST) films have been deposited onto (100) LaAlO₃, SrTiO₃, and MgO substrates. Interdigitated capacitors have been used to measure the dielectric constant and dissipation factor of these films as a function of DC bias and temperature at 1 MHz and as a function of DC bias at 1 to 20 GHz at room temperature. A low phase noise voltage controlled oscillator is currently being developed for use at frequencies from 1 - 20 GHz. To achieve low phase noise in the oscillator will require the loss tangent in the ferroelectric to be <EQ 5 X 10^-3. Origins of the dielectric loss are being investigated using optical techniques. Optical imaging of the ferroelectric films using confocal scanning optical microscopy shows reproducible polarization fluctuations over sub-micrometer length scales for BST films deposited onto SrTiO₃ which are not observed for films deposited onto MgO. Dielectric loss in the ferroelectric film is reduced through a combination of post deposition processing and donor/acceptor doping of the films. The lowest dielectric loss measured at microwave frequencies (tan(delta) equals 0.01 at 1 - 10 GHz) has been in a post-deposition annealed Ba_0.5Sr_0.5TiO₃ film doped with approximately 1 - 2 atomic % Mn.

Pulsed laser deposition has been used for the growth of high quality YBa₂Cu₃O₇ and La_0.67Sr_0.33MnO₃ thin films and multilayers for electronic device applications. In particular, YBa₂Cu₃O₇ - (SrTiO₃, CeO₂) - La_0.67Sr_0.33MnO₃ trilayer devices were fabricated to study the supercurrent suppression by the injection of a spin-polarized quasiparticle current. Our results show that the critical current for a YBa₂Cu₃O₇ - 50 angstroms SrTiO₃ - La_0.67Sr_0.33MnO₃ device was found to decrease from 120 mA to 15 mA, for an injection current of 60 mA of spin polarized current yielding a negative current gain of approximately 1.8. The effect of film microstructure on the critical current suppression was investigated. Defects in the SrTiO₃ and CeO₂ layers were found to control the device properties. Once optimized, spin injection represents a new approach to fabricating superconducting transistors which could impact electronic systems for many important next generation.

In order to fabricate functional organic thin films, we investigated organic molecular beam deposition combined with laser-induced chemical reactions. Bis(ethynylstyryl) benzene (BESB) films of trans,trans-isomer were deposited by this new method. The cis,cis-BESB was sublimed and cis-to-trans photoisomerization was induced upon KrF excimer laser irradiation ((lambda) equals 248 nm). The growth of the well- oriented crystalline films was achieved upon the laser irradiation during the deposition at the substrate temperature of 60 degree(s)C. At this substrate temperature only trans,trans-BESB was deposited on the substrate surface, which indicated that unreacted cis,cis-isomer was re- evaporated from the substrates. It can be explained that the crystal growth favorably proceeded due to the enhancement of the surface migration of the trans,trans-isomer and no hindrance of the cis,cis-isomer. We also fabricated thin films of a reaction product by inducing an intermolecular reaction of BESB with biphenyl-dithiol upon the laser irradiation during the deposition. It is thus found that the new process made it possible to produce the functional organic thin films, which were difficult to be evaporated by the conventional vacuum process. We discussed the chemical reactions and the deposition behavior in our process.

A lab scale nonflowing reactor was built to study chemical vapor deposition reactions and for the purpose of minimizing the waste of expensive high purity and toxic gases. The reactor operates as a batch process resulting in a time varying gas composition during the course of deposition. Samples were heated either resistively (thermal CVD) or with focused laser light (laser CVD). X-ray measurements were made on the deposited tungsten samples. Obtained results (tungsten structural parameters) were compared with the same parameters obtained for the tungsten films deposited in a commercial, flowing CVD process.

Laser-induced intermixing of quantum well (QW) and barrier material has been studied in GaInAsP/InP laser heterostructures grown by chemical beam epitaxy. Samples were exposed to CW Nd:YAG laser radiation for 7.5 to 300 sec with power densities in the range of 3 to 9 W/mm². With a laser beam tightly focused on the surface, this approach has the potential to `write' lines of arbitrary shapes of quantum well intermixed material. A 90 nm blue shift of the QW PL peak was demonstrated in the material processed with a triple pass of the 7.5 W/mm² laser beam. This result has been achieved with a writing speed of 20 micrometers /s. The influence of laser power, dwell time per pass and total irradiation time of the Nd:YAG laser beam on the extent of the blue shift and the optical properties of GaInAsP-based quantum well structures were investigated.