Laser manipulation of the size and shape of metal nanoparticles generated by self-assembly of atoms on dielectric substrates is discussed. Techniques are presented that allow one to prepare nanoparticles with a narrow size distribution and with well-defined shape by using laser irradiation after and during particle growth. Optical spectroscopy of supported nanoparticles is demonstrated to be a very versatile tool for characterizing the particles in addition to direct imaging by scanning probe microscopy. We also show that laser manipulation of the size or shape of nanoparticles can be used to determine the homogeneous linewidth of surface plasmon excitation and thus examine the ultrafast decay time of this collective electron oscillation in nanoparticles. Prospects for future experiments in this field and applications of monodisperse nanoparticles are outlined.

The laser photopolymers and the laser imaging systems equipped with various laser diodes such as 410 nm-Violet laser, 532 nm-frequency-doubled laser and high-power- infrared laser are presented. The photopolymer's performances in sensitivity, resolution and safelight character dependent on the wavelength and power of laser light are discussed.

This paper presents investigation results of drilling of metal microcomponents by copper vapor laser. The laser consists of master oscillator - spatial filter - amplifier system, electronics switching with digital control of laser pulse repetition rate and quantity of pulses, x-y stage with computer control system. Mass of metal, removed by one laser pulse, is measured and defined by means of diameter and depth of holes. Interaction of next pulses on drilled material is discussed. The difference between light absorption and metal evaporation processes is considered for drilling and cutting. Efficiency of drilling is estimated by ratio of evaporation heat and used laser energy. Maximum efficiency of steel cutting is calculated with experimental data of drilling. Applications of copper vapor laser for manufacturing is illustrated by such microcomponents as pin guide plate for printers, stents for cardio surgery, encoded disks for security systems and multiple slit masks for spectrophotometers.

Next generation photolithography stepper tools will operate at 157 nm and require robust solid state photodetectors to ensure efficient operation and facilitate direct beam monitoring for photoresist dosimetry. There is currently no commercial detector system able to fully meet all the demanding requirements of this application. Diamond has a band gap of 5.5 eV. This implies that detectors fabricated from this material may be intrinsically visible blind and radiation hard. In this paper the results of the first study to assess the viability of the use of thin film polycrystalline diamond photodetectors for use in 157 nm F₂-He based laser lithography tools are presented. Co- planar interdigitated electrode structures were fabricated on free standing polycrystalline diamond to realise photoconductive devices. These were exposed to pulses from an F₂-He laser in the fluence range 0 - 1.4 mJcm^-2. The electrical and optical characteristics of the devices have been measured and are compared to the response of a standard vacuum photodiode. The diamond devices appear to be ideally suited for use at 157 nm in lithography applications.

Surface modification of aluminum alloy 2024-T3 using femtosecond pulsed excimer laser irradiation was studied at 248 nm. The images of the scanning electron microscopy (SEM) were characterized as a function of incident laser fluence. Results indicated that the surface features, ranging from nano- to microdimension, can be developed through variation in laser fluence intensities and pulse counts. Two ablation regimes in the logarithmic fluence dependence of the ablated depth for the 500 fs-pulse irradiation were observed. The theoretical analysis for ablation processes is in a good agreement with the experimental results.

The purpose of this work is to investigate microscale laser bending and to compare the results of bending using a pulsed and a CW laser. Samples of ceramics (Al₂O₃/TiC), silicon, and stainless steel are bent at various laser processing conditions. Changes of surface composition after laser irradiation are analyzed using an electron probe microanalyzer (EPMA). Comparisons of CW vs. pulsed bending are made in terms of the amount of bending and the damage to the specimens.

Laser ablation and etching of microcrystalline Cu- phthalocyanine thin films were examined by changing pulse duration (170 fs, 250 ps, 100 ns) of a 780 nm Ti:sapphire laser. Above fs (40 mJ/cm²) and ps (50 mJ/cm²) ablation thresholds, the etch depth becomes constant and is almost independent of laser fluence, and further increase in the fs fluence results in complete removal of the film. We name the unique ablation phenomenon discrete etching. On the other hand, the depth etched by ns laser excitation increases gradually with the fluence above its ablation threshold (80 mJ/cm². In order to reveal the difference between the fs and ns etching behaviors, we measured directly excitation energy relaxation and surface morphology change with time-resolved absorption spectroscopy and time- resolved surface scattering imaging, respectively. The fs discrete etching phenomenon and its mechanism were considered in view of time evolutions from highly intense fs laser excitation to the step-wise etching. On the basis of the results, we propose an fs laser ablation model that ultrafast stress increase brings about mechanical disruption leading to the discrete etching behavior.

In this paper, basic examinations on the laser cutting of silicon using ultrashort ((tau) _H equals 150 fs) laser pulses are presented. The influence of the polarization on the cutting process is investigated. It was found that significant deviations from the ideal cut geometry occur if the polarization is parallel to the cutting motion. An innovative automated method using image processing to assess the quality of cuts is discussed. On the basis of this method, it is shown that the deviations increase with the depth of the cut. Hence, it is suggested that deviations are caused by reflection. Two models for simulating the influence of different polarizations on the intensity distribution on the ablation ground for cutting and drilling are discussed.

We report investigation of light-induced damage threshold (LIDT) in purified silica (transmission band down to 160 nm) by 350 fs laser pulses at the wavelength of 795 nm and 498 nm. Focusing a single pulse by a high numeric aperture NA equals 1.35 microscope objective lens results in one of the lowest single-show bulk LIDT values reported so far, 5 J/cm², while the surface ablation threshold is 2.5 J/cm² with both values being well below the critical self-focusing power in silica. Furthermore, we report the peculiarities of damage by two-pulse irradiation (duration experimental data and numeric simulation, which takes into account optical free-carrier generation and relaxation, demonstrates that these processes can explain the measured self-focusing, super-continuum generation, and light-induced damage threshold values. We argue that use of high numeric aperture objective, despite substantial temporal pulse stretching, results in tight focusing which is capable of overcoming the beam self-focusing, and the resulting fabrication quality is comparable to that obtained using shorter pulses.

Possibilities to fabricate sub-micron structures in thin metal films, metal coatings, and glass substrates using femtosecond laser pulses are systematically studied. Structures are produced by direct femtosecond-pulse laser ablation of solid targets at atmospheric pressure. Tight focusing and imaging techniques are applied. Dependencies of the structure size on laser pulse energy and pulse number are investigated.

Increasing miniaturization and integration of multiple functions into portable electronic devices and sensors ask for smaller electrical components. Conventional abrasive processes often reach their technological limit resulting in the demand for alternative technologies with increased precision and performance. Lasers have been proven to be a suitable tool for micromachining, but often suffering the disadvantage of heat or shock affected zones around the machined structures. To be feasible as an industrial solution, new approaches have to provide very high precision and process stability with minimal collateral damage. Presently, two different approaches for laser machining of semiconductor materials are being investigated. Although the interaction mechanism is completely different as described within this paper, both are regarded as promising technologies: ultrashort-pulse and short wavelength laser machining. Femtosecond laser machining has been used for a variety of applications, showing the advantage of non-thermal ablation of many kinds of materials. Due to the short pulse duration and the high intensities multi-photon absorption allows to overcome the bandgap of semiconductors while not affecting the bulk material. Due to the short wavelength excimer lasers as well as fluorine lasers provide the general ability to generate small spot sizes and emit photons with higher energies compared to the bandgap of the material, e.g. of silicon. Both technologies will be discussed and compared, and applications for micromachining of silicon will be presented.

Bulk laser modification is reported for hydroxyl (OH), chlorine (Cl) and fluorine (F) containing fused-silica glasses irradiated with 157-nm F₂-laser light. We detail the effects of OH, Cl and F concentration, as well as hydrogen (H₂) loading, on compaction, refractive-index change, and color-center formation. Volume gratings formed with several tens of kJ/cm² fluence yielded surface-relief gratings of several tens of nm amplitude and bulk refractive-index changes of nearly 10^-3 in both OH- and Cl-content glasses that were pre-soaked in high-pressure hydrogen. H₂-loading offered an approximate 2-fold increase in 157-nm glass photosensitivity, and also increased the 157-nm material absorption by several factors during the exposure. In contrast, F-doped glass did not offer a measurable 157-nm photosensitivity, and the 157-nm absorption showed a surprising order-of-magnitude drop following an approximate 10-kJ/cm² laser dose.

Etching of GaN by ablation using KrF excimer or F₂ laser has been demonstrated, as well as simultaneous irradiation of F₂ laser with KrF excimer laser to GaN has been explored. The GaN etching process is consisted of the following sequential procedures: laser ablation and an acid chemical treatment for residue removal. Single-pulse irradiation of KrF excimer laser as well as F₂ laser planarizes the etched GaN surface. Multiple KrF irradiation roughens etched GaN surface significantly; however, low intensity F₂ laser simultaneously irradiated with the KrF excimer laser improves the surface roughness. Complete removal of 700 nm-GaN is accomplished by 10 pulses with a laser intensity of approximately 40 x 10⁶ W/cm², besides, very sharp etching sidewall and extremely flat sapphire surface are obtained.

Collinear irradiation system of VUV-UV multiwavelength excitation process using F₂ and KrF excimer lasers has been developed. This system achieves high-quality ablation of fused silica. In addition, dependence of ablation rate on various conditions such as laser fluence, delay time of each laser irradiation, and pulse number is investigated. Multiwavelength excitation effect is strongly affected by the delay time and extremely high etching rate over 30 nm/pulse is obtained during -10 ns to 10 ns of the delay time. KrF excimer laser ablation threshold decreases and its effective absorption coefficient increases with increasing simultaneously irradiated F₂ laser fluence.

The combination of a wavelength tunable UV free electron laser and a high resolution photo-electron emission microscope offers unprecedented opportunities for in situ, real time imaging of the dynamics of processes on surfaces on a nanometer scale. This type of system is now in operation at the Duke University Free Electron Laser Laboratory. In this study we report real time observations of the dynamics of liquid Pt-Si islands on Si(100) surfaces. The dynamics of coalescence is observed. Moreover, a driving force for motion of the liquid micro-droplets is developed based on these observations. We also report studies of the dynamics of growth of nanometer scale TiSi₂ islands on Si(111). Depending on the growth conditions, we observe ripening or coalescence processes where smaller islands evolve into larger islands. On the (111) surface a shape transition is observed in which the islands are initially circular and then develop into long wire shaped structures. The growth processes represent a competition between kinetic and energetic processes on the surfaces.

Using Laguerre-Gaussian beams in an inverted optical tweezers geometry we observe that silver particles, 2 microns in diameter, are confined to an annulus around the outside of the beam. This annulus is situated 4 microns below the beam waist where the upward scattering force counterbalances gravity. The scattering force results in a transfer of the orbital angular momentum content of the beam to the particle causing it to rotate about the beam axis.

The Thermal Resist Enhanced Optical Lithography (TREOL) process models an optical system to double device resolution by exploiting non-reciprocal laser activated processes. A possible prototype thermal resist consists of stacked bismuth on indium layers sputter deposited on a glass/quartz substrate with thickness ratios matching the eutectic alloy (Bi 53%). Laser radiation locally melts the metals which alloy upon cooling. BiIn resist is relatively wavelength insensitive because its UV optical characteristics vary modestly. Reflection and energy absorption/cc calculations indicate the best arrangement is a 30-45-nm total thickness bilayer with bismuth on indium. Exposing the highly absorbing BiIn with CW argon (514/488 nm) or 4-ns Nd:YAG pulses at 533 nm (40 mJ/cm² for 300-nm thick) and 266 nm transforms the resist to a weakly absorbing alloy with a visually identifiable pattern. 30-nm thick converted film transmission changes from 1.0OD to 0.35OD (830-350 nm) until a 350-nm absorption edge. Profilometry and SEM showed no signs of ablation or oxide growth in exposed areas. The resist was developed with HNO₃:CH₃COOH:H₂O etch, preferentially removing unexposed areas, leaving written patterns of alloyed lines seen both in profilometry and SEM images. Thus BiIn forms a complete thermal alloying resist with selectively etched exposed patterns that can be stripped in an HCl:H₂O₂:H₂O bath.

Transparent conducting indium tin oxide (ITO) thin films were grown by pulsed laser deposition (PLD) on glass and on flexible polyethylene teraphthalate (PET) substrates. The structural, electrical and optical properties of these films were investigated as a function of substrate deposition temperature and background gas pressure. Films were deposited using a KrF excimer laser (248 nm, 30 ns FWHM) at a fluence of 1.2 J/cm². Films were deposited at substrate temperatures ranging from 25 degree(s)C to 150 degree(s)C in oxygen pressures ranging from 10 to 60 mTorr. ITO films (280 nm thick), deposited by PLD on PET at 25 degree(s)C and 45 mTorr of oxygen, exhibit a low electrical sheet resistance (20 - 25 (Omega) /sq.) and high transparency (approximately 85%) in the visible range (400-700 nm). We have also used the ITO thin films deposited on both glass and PET substrates by PLD as the anode contact in organic light emitting devices (OLEDs) and measured the device performance. The external quantum efficiency measured at a current density of 250 A/m² for the device on PET was approximately 0.9%, which is higher than that (approximately 0.5%) for the device on glass. The reduction in the driving voltage and high external quantum efficiency made an ITO coated PET substrate very promising for future large scale OLED application.

Laser-induced forward transfer (LIFT) was applied to eject the particles placed on a thin film. The behavior of the fluorescent particles in the gas phase was observed by a two-dimensional laser-induced fluorescence (2D-LIF) technique. The behavior of emissive particles was also imaged. The speed of the particles was in the order of few hundreds m/s, and changed with ablation conditions. The fastest speed was around 280 m/s.

We have utilized pulsed-laser ablation in ambient inert gas to synthesize silicon (Si) nanoparticles and to perform surface modification and impurity doping. The dynamical growing process of Si nanoparticles has been investigated by measuring time-resolved light emission induced by the second pulsed-laser irradiation with a delayed time. It was found from the time-resolved measurements that the onset of the formation of Si nanoparticles appears at around 1 ms, on inert gas pressure and laser fluence. We demonstrate that light emission can be controlled by adding hydrogen or oxygen gas to inert gas. It is also demonstrated that the thermal quenching which has been serious problem in Er-doped semiconductors can be removed in 1.54 micrometers photoluminescence of Er-doped Si nanocrystallites. These results suggest that laser ablation is useful not only for synthesis of nanostructured materials such as nanoparticles and nanowires/nanotubes, but for their surface modification and impurity doping that are important techniques for realizing functional nanostructures.

Photo-dissociation and laser ablation of solid nitrogen film at 10 K was carried out upon irradiation with a picosecond UV laser (FHG of Nd:YLF laser; 263 nm, 8 ps, 10 Hz) in vacuum. The optical emission lines, attributed to molecular and atomic nitrogen of the film, were monitored by a time-resolved spectroscopic technique. The mechanism of these processes was discussed on the basis of multi-photon absorption of molecular nitrogen.

There is much interest in using subnanosecond pulsed lasers for micro-machining due to the ability of these lasers to machine very precise features. The micro-machining precision of these lasers is a result of the reduced thermal diffusion depth compared to that obtained using longer laser pulses. Experimental research in the literature shows evidence of thermal mechanisms, such as recast layers and thermal distributions of ejected particles, but claims that normal evaporation is responsible are not justified by kinetic calculations. This work critically reviews the experimental evidence from literature and the possible thermal mechanisms that may participate during subnanosecond laser ablation. Phase explosion (due to homogeneous vapor nucleation) is shown to be the most likely mechanism of mass removal; however, there are many questions regarding how phase explosion proceeds on a subnanosecond time scale. Theoretical estimates of the time lag required for reaching an equilibrium distribution of vapor nuclei have been associated with the time required for ablation to proceed. This time lag is on the order of one nanosecond or longer, raising many questions about the validity and applicability of this calculation. This work studies phase explosion and the associated time lag and discusses topics for future research.

Experiments on deep drilling of steel by 300 ps, 1 ps and 125 fs laser pulses are reported. The ablation rate dependence on the channel depth was studied and energy losses in through channels for different radiation parameters were measured. The low-threshold cluster-assisted air breakdown was revealed to play an important role in ablation by 300 ps pulses. The ablated particles remaining inside the channel between laser shots provide substantial reduction of the air breakdown threshold. Laser-induced spark produces noticeable shielding effect and, presumably, is main reason of observed deep channel widening. Pronounced strengthening of light shielding by laser-induced spark was observed under steel target ablation comparing with pure air without target for ultrashort (125 fs, 1 ps) laser pulses. The dramatic reduction of the drilling rate in deep channels was observed for all examined pulsewidths. In the case of 300 ps pulses, the drilling rate falls down sharply by two order of magnitude at a certain critical channel depth increasing with the incident laser fluence. It was found that the integral plasma transmittance (breakdown plus ablation) remains unchanged when the drilling rate decreases.

We report the onset of plume formation and optical breakdown in a synthetic silica glass under KrF excimer laser irradiation by luminescence spectroscopy and imaging. With increasing laser fluence, bright, highly localized luminescence due to plume formation appears on the luminescence image, and sharp lines due to Si atom fluorescence appear in the 200-300 nm region on the luminescence spectra. The SEM images on the laser-damaged region show typically two structures: (1) many small holes of the order of 1 micrometer suggesting localized vaporization, and (2) large craters of 10-100 micrometers due to spallation. The large craters have irregular shapes consistent with fracture often seen in amorphous materials.

Polyperinaphthlenic organic semiconductor (PPNOS) films with polyperinaphthalene (PPN) structure for anode electrodes for ultra thin rechargeable Li ion batteries are prepared on temperature-controlled substrates by excimer laser ablation (ELA) of 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) or mixture target of PTCDA with a few metal powder (PTCDA/M) using a 308 nm (XeCl) pulsed excimer laser beam. It is demonstrated that ELA of PTCDA at a fluence of less than 0.5 Jcm^-2pulse^-1 enables us to obtain PPNOS on a substrate at 300 degree(s)C. It is found that ELA of PTCDA/Co at a fluence of more than 1.0 Jcm^-4pulse^-1 leads to produce effectively fragments without anhydride groups of PTCDA. FT-IR and Raman spectroscopies reveal that ELA of PTCDA/Co enables us to obtain better-defined PPN films with electric conductivity of approximately 1x10^-1Scm^-1 on a substrate at 300 degree(s)C. Electrochemical doping characteristics of lithium ion into the films obtained by ELA are performed to verify the lithium doping mechanism by in situ Raman spectroscopy. Furthermore a trial piece of thin lithium ion rechargeable battery with the films is fabricated to appraise performance of the films as anode thin electrodes for ultra thin rechargeable lithium ion batteries.

The area of display devices has experienced extremely rapid growth in recent years and these advances show no sign of declining. One of the major developments in this field has been the use of lasers for various microfabrication tasks. This paper describes some techniques which have been developed using excimer lasers for the production of novel microstructures in polymer materials. Examples of the types of microstructures which are produced are presented and their applicability for display device applications is outlined. Forthcoming developments in the laser manufacture of displays are discussed.

We use high intensity nanosecond laser pulses of different wavelengths to modify thin film coatings (silica and titania) on the surface of silicon. We find that films as thick as 1 micron can be removed from the surface in one shot with minor or no damage to the Si surface. We also find the accumulated effect of multiple pulse irradiation. Finally we report our preliminary results on phase transformations in titania films induced by high intensity laser.

The usage of laser treatments for production of semiconductor elements becomes necessary in order of it is great advantages. The traditional methods for preparation of photosensitive layers from A²B⁶ compounds are vacuum evaporation, cathode or magnetron sputtering with additional thermal treatment and usage same techniques for contact areas formation of In, Ga, Al, Cd, CdO. The creation of Om- power points for solar elements, using CdS an n-layer, continues to be a problem because of the necessity of transparency and linear characteristics. In this paper is offered a method for preparation of solar cells deposited by vacuum evaporated on cital substrate with additional laser treatment by CW CO₂ laser and in situ formation of Om- power points from CdO over a layer of CdS using UV TEA N₂ laser. The electronic and compositional properties of solar cells were analyzed by XRD, XPS, and SEM. Using vacuum evaporation of CdS on cital substrate and laser treatments of layers in powder of CdS, CdCl₂ and CuCl, the photosensitivity of CdS layers has been improved by 8 orders of magnitude, which makes them suitable for solar cells and photoresistors with planar Om contact areas from CdO with very high transparency - about 80% while it is about 1% for the metal power points.

This paper discusses the use of high power lasers in the manufacture of microelectromechanical systems (MEMS). The ability to process a wide range of materials, and to produce truly three-dimensional structures with tolerances at the micron or sub-micron level, give laser micromachining some key advantages over other more established micromachining techniques. Previous work in this area is reviewed, covering the following topics: use of ablation in the direct fabrication of MEMS devices and to define polymer masters for subsequent replication by electroforming and moulding (the so-called Laser-LIGA process); laser-assisted deposition and etching on planar and non-planar surfaces; laser-assisted manipulation of microparts and laser-assisted assembly.

Excimer laser ablation of polymers is demonstrated to be a well suited technology for cost effective fabrication of prototypes of polymer microstructures in relatively short times. Prototyping is realized by ArF excimer laser ablation (193 nm) using mask projection techniques in combination with high precision sample movement as well as mask movement. Different techniques and their restrictions in structural diversity are illustrated by examples from micro-optics, like fiber switches and waveguide couplers. Microparts the functionality of which has been proven by prototypes can be fabricated in large numbers by the Laser-LIGA technique. For the Laser-LIGA process a master structure is generated in PMMA that is coated onto a titanium wafer, using the same CNC data as for rapid prototyping without additional expenditure. From the PMMA master a mould insert of Ni or Cu can be generated by electroforming that allows time and cost effective mass fabrication via hot embossing or injection moulding if the required part numbers are large. Advantages and disadvantages of the laser ablation prototyping technique compared to other rapid prototyping methods are discussed and the Laser-LIGA technique is compared to the standard LIGA process using deep X-ray lithography.

A novel laser-based process developed at the Naval Research Laboratory has been used to fabricate pseudocapacitors and microbatteries with tailored capacities for small electronic devices having size and/or weight restrictions. This process, called MAPLE DW (for matrix-assisted pulsed-laser evaporation direct write) can deposit rugged mesoscale (1 micrometers to 10 mm) electronic components over any type of substrate. A pulsed laser operating at 355 nm is used to forward transfer material from a tape-cast ribbon to a suitable substrate to form a precision design. With MAPLE DW, customized mesoscale electronic components can be produced, eliminating the need for multiple fabrication techniques and surface-mounted components. Direct write processing is especially attractive for the fabrication of micro-power sources and systems. The versatility of laser processing allows battery designs to be easily modified. Batteries and/or pseudocapacitors can be integrated with power management electronics to deliver a wide range of power outputs. By building power sources directly on electronic components, the weight of the power sources is decreased as the electronic substrate becomes part of the battery packaging and the lengths of interconnects are shortened, reducing conductor losses. RuOxHy pseudocapacitors deposited with MAPLE DW show good storage capacities. Pads of hydrous RuO₂ having dimensions of 2.2 mm x 1.0 mm x 30 micrometers have been deposited in a planar configuration on gold current collectors. Rechargeable Zn/MnO₂ alkaline microbatteries comprising of MnO₂, Zn, an ethyl cellulose separator barrier layer and a KOH electrolyte have also been fabricated by MAPLE DW. The resulting structures with dimensions of 1.5 mm x 1.5 mm x 60 micrometers represent the first demonstration of a multilayer microbattery made by MAPLE DW. The performance of these prototypes are shown and the potential impact of MAPLE DW for the fabrication of novel microbattery systems for integrated power applications are discussed.

Tungsten microcone arrays with a high aspect ratio, which protrude from the initial surface of a target material, have been formed by Nd:YAG laser irradiation of tungsten in a low pressure inert gas atmosphere. The laser fluences were 1.5- 9.6 J/cm² at SHG. The tungsten substrate was irradiated with 1-3600 pulses. The microcone growth was strongly affected by the number of laser pulses. The microcones were up to 20 micrometers tall and had about a 1.5 micrometers diameter at the tip. Several ten or several hundred pulses caused only a rough surface while subsequent pulses created the microcone arrays. Silicon, polymer, and oxides were used as the target materials in the former studies. The growth on these substrates could be attributed to the presence of various impurities and chemical gases. However, we used no impurities or chemical gases in this experiment. We believe that the growth mechanism of the microcones might be different from this study. It was concluded that the melted/solidification tungsten tip induced by the repetition of the pulsed laser irradiation on the top surface plays a significant role in the formation of the microcones. These tall tungsten microcone arrays might be very attractive for various industrial applications.

The rapid fabrication of microcomponents made from polymers will be presented. The whole fabrication process is divided into three main steps: First, direct patterning of polymers with excimer laser radiation enables the fabrication of first prototypes. Second, laser assisted micromachining using Nd:YAG and KrF-Excimer laser allows a rapid manufacturing of microstructured mold inserts. Third, the application of light induced reaction injection molding (UV-RIM) gives the access to the replication of the previously fabricated mold insert. The fabrication of prototypes made of polymer is carried out highly precisely with excimer laser radiation. With the aid of a motorised aperture mask, CAD data are transmitted directly into the polymeric surface. With an appropriate pretreatment of the polymer surface the debris formation can be drastically reduced. A promising method of micropatterning of mold inserts made of steel is called laser microcaving. This processing technique enables a clean patterning process with only a small amount of debris and melt. The etch rate and surface quality strongly depend on the chemical composition of the steel and the process parameters. Surface qualities with a roughness of about 300 nm can be achieved. Microstructures composed of polymers or ceramic-composites are successfully demolded by using the UV-RIM technique with aspect ratios up to 10. Capillary Electrophoresis-Chips made of PMMA are fabricated, and the functionality of the CE-Chips is demonstrated.

A set of new laser-light delivery microtools (LDM) based on laser technology is investigated and discussed. Wide application of LDM in different fields of science, medicine, biology, industry and information processing is considered. Fiber optical networks in medical diagnostics and technical, civil engineering and other technological areas are discussed. The general approach based on electromagnetic field equations-transformation for all range of dimensions (mini-, micro and nanodomain) is given. Laser-assisted technology for drawing-out and for microstructuring optical tools is investigated, high-speed movie has been applied to study the process and compared with theoretical description. Finally a number of fibers and micropipettes-based medical tools and SNOM-tips has been fabricated and tested. Applications of some tools for medical operations (thermocoagulation), protein rasters preparing, SNOM-microscopy investigation have been demonstrated.

The world's first micro stereo lithography, named IH process, was proposed and developed by the speaker in 1992. By now, several types of micro stereo lithography systems have been developed. Three-dimensional resolution of solidification has reached to 0.2 micron at present. These 3D micro fabrication processes using UV curable polymer gave a big impact on not only MEMS but also optics. The latest version of IH process enables us to make a movable micro mechanism without assemble process or sacrificial layer technique often used in silicon process. It is well known that the IH process is the mother of two-photon micro stereo lithography and its applications. Recently new micro chemical device named Biochemical IC Chip was proposed and developed by the speaker. This chip is based on the module IC chip-set like today's TTL family. IH process enable to make the biochemical IC including real three-dimensional micro fluid channels. Various kinds of Biochemical IC chips such as micro pump, switching valve, reactor, concentrator and detector have already been fabricated successfully. Basic performance of micro chemical devices constructed by the biochemical IC chips were demonstrated. The biochemical IC chips will open new bioscience and medicine based on innovative technology.

A novel laser-assisted technology for the additive fabrication of microelectronic circuits on three-dimensional polymer substrates (Molded Interconnect Devices, 3-D MID) has been developed. Advantages of the ADDIMID-approach are: a very short process chain, no etchants, no coatings (important on 3D substrates), industry-proven laser technology (diode-pumped Nd:YAG) and high writing velocity (greater than 600 mm/s). An essential component of the process is a special composite substrate material. The material consists of a polymer matrix containing finely dispersed microcapsules. The microcapsules are fabricated by coating micron-scaled copper powder with nano-scaled SiO₂. The SiO₂ coating provides electrical insulation of the copper particles and promotes adhesion to the polymer matrix. The microcapsules are mixed with a thermoplastic base material to form a granulate. Polymer substrates are produced by injection-molding. A laser direct-write process with galvanometric beam deflection is used to generate the circuit pattern. The laser uncovers the microcapsules and removes the SiO₂ coating. Metallic copper is exposed in the processed surface regions. The exposed copper acts as catalytic nucleation site. The circuitry is then formed by chemical copper-plating. This paper presents experimental investigations on direct writing with a CO₂- and a diode-pumped Nd:YAG-laser. Effects of variations in focus position, writing velocity, and pulse frequency are described and specified with regard to their impact on the quality of the circuit patterns. A phenomenological model of the laser direct-write process is outlined.

A novel laser trimming technique, fully compatible with conventional CMOS processes, is described for analogue and mixed microelectronics applications. In this method, a laser beam is used to create a resistive device by melting a silicon area, thereby forming an electrical link between two adjacent p-n junction diodes. These laser diffusible resistances can be made in less than a second with an automated system and their values can be in the range of 100 ohms to a few M ohms, with an accuracy of 50 ppm, by using an iterative process. In addition, these resistances can also be made to possess a thermal coefficient close to zero. We present the method used to create these resistances, the main device characterization and some insight on the process modeling.

A novel method is presented to produce a high precision pattern of copper tracks on both sides of a 4-layer conformal radar antenna made of PEI polymer and shaped as a truncated pseudo-parabolic cylinder. The antenna is an active emitter-receiver so that an accuracy of a fraction of the wavelength of the microwave radiation is required. After 2D layer design in Allegro, the resulting Gerber file-format circuits are wrapped around the antenna shape, resulting in a cutter-path file which provides the input for a postprocessor that outputs G-code for robot- and laser control. A rules file contains embedded information such as laser parameters and mask aperture related to the Allegro symbols. The robot consists of 6 axes that manipulate the antenna, and 2 axes for the mask plate. The antenna can be manipulated to an accuracy of +/- 20 micrometers over its full dimensions of 200x300x50 mm. The four layers are constructed by successive copper coating, resist coating, laser ablation, copper etching, resist removal, insulation polyimide film lamination and laser dielectric drilling for microvia holes and through-holes drilling. Applications are in space and aeronautical communication and radar detection systems, with possible extensions to automotive and mobile hand-sets, and land stations.

Laser induced copper deposition from solid copper formate precursor films has been studied on polyimide, FR4 and Al₂O₃ substrates. Unlike most work reported in the literatures, we used 532 nm Nd:YAG laser beam instead of CW Ar⁺ laser for the process. A writing speed of 10 mm/s was achieved for deposition of micron-thick copper lines with a typical electrical resistivity of around 85 (mu) ohm-cm. To further increase the electrical conductivity and copper thickness, selective electroless copper plating was performed on the laser processed sample. This has reduced the electrical resistivity of the copper line to below 5 (mu) ohm-cm that is about 3 times the value of bulk copper (1.673 (mu) ohm-cm). A typical copper thickness exceeding 10 micrometers has been achieved after the electroless plating process. The surface morphology and chemical composition were analyzed by using SEM and EDS. The copper line was found to adhere well to the substrate. Besides circuit repair and customization, the reported technique is potentially useful for rapid prototyping of PCB circuits.

Miniaturization is one of the keywords for the production of customer oriented and highly integrated consumer products like mobile phones, portables and other products from the daily life and there are some first silicon made products like pressure sensors, acceleration sensors and micro fluidic components, which are built in automobiles, washing machines and medical products. However, not all applications can be covered with this material, because of the limitations in lateral and 3-dimensional structuring, the mechanical behavior, the functionality and the costs of silicon. Therefore other materials, like polymers have been selected as suitable candidates for cost effective mass products. This holds especially for medical and optical applications, where the properties of selected polymers, like biocompatibility, inert chemical behavior and high transparency can be used. For this material laser micro processing offers appropriate solutions for structuring as well as for packaging with high flexibility, material variety, structure size, processing speed and easy integration into existing fabrication plants. The paper presents recent results and industrial applications of laser micro processing for polymer micro fluidic devices, like micro analysis systems, micro reactors and medical micro implants, where excimer radiation is used for lateral structuring and diode lasers have used for joining and packaging. Similar technologies have been applied to polymer waveguides to produce passive optoelectronic components for high speed interconnection with surface roughness less than 20 nm and low attenuation. The paper also reviews the technical and economical limitations and the potential of the technology for other micro products.

The ablative decomposition of GaN films induced with a XeCl excimer laser ((lambda) equals 308 nm) was investigated for a potentially low-damage surface planarization process. Samples, 2-micrometers -thick, were grown on (0001) sapphire by ammonia molecular beam epitaxy. They had a characteristic micro-hillock type surface morphology with a roughness, averaged over 5 x 5 micrometers ² area, typically, of 13 nm. Following the laser irradiation, this roughness could be reduced to 3.6 nm. The results indicate that the ablation process follows the Lambert-Beer's law, with an absorption coefficient of 3 x 10⁵ cm^-1. The experiment was carried out with relatively short pulses ((tau) equals 10 ns), which appear to be responsible for the observed onset of the laser-induced decomposition of GaN and surface planarization at significantly smaller laser fluences than reported in the literature. The ability to carry out decomposition of GaN with low laser fluences is of practical importance for achieving a low-damage GaN planarization process and/or intentional delaminating of this material from the sapphire substrate by the back side irradiation technique.

A polymer multilayer was spin coated on a substrate and was structured with pulsed KrF-excimer laser radiation to generate optical waveguides. Ablation rate, surface roughness and wall-angles were determined using white light interferometry, atomic force microscopy and light microscopy. Polymeric waveguides can be used for optical transmission and their properties such as mode propagation and absorption losses were determined with beam diagnosis. However, compared to other structuring techniques absorption losses of the waveguides are high. One reason for this is the formation of debris on the surface of the waveguides during the process of structuring. Therefore, an investigation of the distribution of debris during structuring was conducted. Different types of processing gases and pressures were used to decide which configuration provides a minimum amount of debris. Absorption losses were again determined and successfully decreased after debris reducing strategies were applied.

A novel method is presented to manufacture multilevel diffractive optical elements (DOEs) in polymer by single- step KrF excimer laser ablation using a halftone mask. The DOEs have a typical pixel dimension of 5 micrometers and are up to 512 by 512 pixels in size. The DOEs presented are Fresnel lenses and Fourier computer generated holograms, calculated by means of a conventional iterative Fourier transform algorithm. The halftone mask is built up as an array of 5 micrometers -square pixels, each containing a rectangular or L- shaped window on an opaque background. The mask is imaged onto the polymer with a 5x, 0.13 NA reduction lens. The pixels are not resolved by the lens, so they behave simply as attenuators, allowing spatial variation of the ablation rate via the window size. The advantages of halftone mask technology over other methods, such as pixel-by-pixel ablation and multi-mask overlay, are that it is very fast regardless of DOE size, and that no high-precision motion stages and alignment are required. The challenges are that the halftone mask is specific to the etch curve of the polymer used, that precise calibration of each grey-level is required, and that the halftone mask must be calculated specifically for the imaging lens used. This paper describes the design procedures for multilevel DOEs and halftone masks, the calibration of the various levels, and some preliminary DOE test results.

J. A. Macken invented CO₂ lasers with distributed gold catalyst in the discharge capillary wall. This type of laser has a bright future for applications. For studying its mechanism, two tubes of lasers, one with distributed gold catalyst, the other without, have been prepared for comparison. In this paper, key techniques for preparing the new type lasers is presented.

Beam-shaping plays a very important role in the field of laser processing. Laser quench needs a rectangular speckle, which has a flat top, steep sides, high efficiency and low sidelobes. Diffractive phase elements (DPEs) have many superexcellent characters, which conventional optical elements have difficulties to achieve. Designing of the phase plane comes down to phase retrieval problem. Geometrical transformation and multiform iterative algorithms, such as G-S algorithm, Input-Output algorithm, ST algorithm are adopted. Through comparison of the results from different methods, some evaluations about algorithms are made. ST algorithm is the most feasible method for the problem, the result of which can meet the requirements of practical process. Some simulation experiments and discussions about algorithms have been done. To be fabricated as a binary optical element (BOE), the result of design has been quantified to 16 steps.

In this paper, the direct ablation of polymer films of PMMA, PI, PC and K9 glass has been studied at wavelengths of 193 nm and 308 nm. The ablation characteristics of microstructuring is mainly discussed and compared. The ablation qualities of PC, PMMA and K9 glass by XeCl (308 nm, 30 ns) excimer laser are very poor. The ablation performances of PMMA and K9 glass by ArF (193 nm, 17 ns) excimer laser are medium. Smooth surfaces and sharp edges with micron transverse resolution and submicron depth precision can be obtained by the ablation of PI at 308 nm, and PI, PC at 193 nm.

Tin oxide active layers were deposited by Pulsed Laser Deposition (PLD) and Laser assisted Chemical Vapor Deposition (LCVD) methods. The films were grown on the same substrate chips for the thin layer conductive sensor. Their chemical and morphological properties were studied in connection with gas sensor applications. The influence of the Pd catalyst was tested. The chemical composition was investigated by XPS analysis. A sensitivity to 1000 ppm of hydrogen of about 1090 for PLD and 5 for LCVD was achieved.

We present, to the best of our knowledge, first demonstration of a direct three-dimensional (3D) microfabrication in the volume of silica glass. The microfabrication was carried out in two steps: 1) recording 3D patterns inside silica glass via silica damaging by focused femtosecond laser pulses (in multishot regime), and sample translation along X, Y, and Z directions; 2) etching the recorded patterns in HF based etchants. Comparative study of chemical etch rates in diluted HF, buffered HF, and a mixture of HF, H₂O and HNO₃ (P etch) reveals direct evidence of structural and/or stoichiometrical difference between damaged and fresh silica. 3D structures consisting of submicrometer size voxels (smallest optically damaged volume element per shot) were successfully fabricated in the silica glass. The presented technique allows fabrication of 3D channels as narrow as 10 micrometers inside silica, with arbitrary angle of interconnection and high aspect ratio (10 micrometers diameter channels in a 100 micrometers thick silica slab). This approach allows to speed up fabrication, and the resulting 3D structures are optically transparent, which is advantageous for optical characterization (transmission, photoluminescence, Raman scattering, etc.) with spatial resolutions determined by focusing optics.

We fabricated the ITO (In-Sn-O) thin film assisted by the infrared free electron laser (12.1 micron-meter-FEL). The novel method can in principle excite the vibration mode of the deposited molecules with matching the FEL energy and the molecular vibration-energy. The method thus is independent of the substrate temperature and has the advantage of fabrication on the low-temperature substrate. The ITO thin- film fabricated by the novel method preliminarily indicates similar transparency to one fabricated by the conventional method.

Power characteristics of four excilamps with short-pulse duration discharge plasma radiation have been investigated experimentally. At mixture pressure of 30 Torr the radiation pulse power density has made at (lambda) approximately 222 nm 0.2 kW/cm², 0.15 kW/cm², 0.09 kW/cm² for I-, H- and L-type excilamps, respectively. The maximal radiation pulse power density was received for modernized I-type excilamp and it has made 0.3 kW/cm². It has been revealed that pulse radiation output is mostly determined by excilamp voltage value, discharge geometry, value of peaking capacitance, and gas medium density.

The importance of surface cleaning is an essential factor in VLSI technology, flat panel display, and data storage devices. The results of laser cleaning technology were studied using KrF excimer laser (248 nm) irradiation in cleanroom environment. The applied energy density was 200 - 800 mJ/cm² at a repetition rate of 10 - 40 Hz with various focused beam widths. Results of photoresist stripping were made before and after laser irradiation with PR covered wafers and comparison of laser cleaning results were investigated as well with bare wafers. The atomic force microscopy (AFM) images of laser cleaning results were also presented and compared before and after laser irradiation. The surface roughness of AFM image of contaminated wafer surface before laser irradiation was 192 angstrom and that of after laser irradiation was 16.2 angstrom. The mechanism of laser cleaning and ablation is rapid thermal expansion of substrate surface induced by an instantaneous temperature rising due to laser irradiation. It is found that the temperature rising of the substrate surface was about 297 degree(s)C with a fluence of 400 mJ/cm² at 300K. Laser dry cleaning technology easily removed fingerprints, submicron Al₂O₃ and SiO₂ particulates intentionally contaminated on the top of the wafer surface without aids of toxic chemicals and deionized water.

A high-resolution 157-nm optical system has been developed for the first time to microprocess optical materials with record short-wavelength F₂-laser radiation. The F₂-laser photons drive strong material interactions in silica glasses for microsculpting surfaces and for imprinting internal refractive index structures. The high-resolution optics deliver a homogenized beam of high on-target fluence (approximately 2.5 J/cm²) for ablation of fused silica and other wide bandgap optical materials. The system resolution is approaching 1-micron lateral and less than 100-nm depth - sub-wavelength features appropriate for defining optical communication components at 1.55-micrometers wavelength. This paper describes this novel processing system and offers prospects for F₂-laser microfabrication and trimming of photonic components in the telecommunication and general optics manufacturing fields.

An Exitech Microstepper exposure tool has been used to laser micromachine a variety of polymeric materials with high resolution at a wavelength of 157 nm. We have demonstrated it is possible to machine thin film materials, different photoresists and fluorine-based polymers with submicron accuracy and resolution. The tool used for this work incorporated a 36x 0.5 NA Schwarzschild lens to project submicron resolution images of binary chrome-on-CaF₂ masks onto free-standing and spun-on polymer films. The beam delivery system and the illuminator includes beam shaping and homogenization optics that allow fluences of greater than 1J/cm² to be produced at the workpiece. Details of the optical system are presented together with process parameters and the results of the materials which have been machined.

A theoretical model describing laser microhole drilling processes in fiber reinforced composites (FRC) has been developed, which can predict the profiles of the microholes for certain incident beam profiles in space. This paper presents the comparison of the calculations and experimental results.

The deposition of different hard ceramics coatings as Al₂O₃, ZrO₂, c-BN and DLC thin films by pulsed laser deposition (PLD) has been of increasing interest as alternative process compared to the latest progress in CVD and PVD deposition. For instance, in pulsed laser deposition, the properties of the resulting thin films are influenced by the composition, ionization state, density, kinetic and excitation energies of the particles of the vapor/plasma. In order to deposit hard ceramics with different properties and applications, various substrates as Pt/Ti/Si multilayer, glass (fused silica), steel, polymethylmethacrylate (PMMA), polycarbonate (PC), Si(100) and Si(111) are used. These thin films are deposited either by excimer laser radiation ((lambda) equals 248 nm) or by CO₂ laser radiation ((lambda) equals 10.6 micrometers ). To characterize the structural, optical and mechanical properties of the hard ceramics thin films, different techniques as Raman spectroscopy, ellipsometry, FTIR spectroscopy and nanoindentation are used.