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PMMA (Polymethylmethacrylate) substrate was covered with 1,2,3,5-tetrafluorobenzene by spin-coating. Then the sample was irradiated by a KrF-excimer laser ( λ = 248 nm). After drying out the polymeric substrate, the sample surface was investigated by SEM and EDX indicating some fluorine content at the top of the sample layer. A UV-photochemical fluorination mechanism is proposed.

Surface relief gratings are written into the surface of a planar PMMA substrate by the UV-excimer laser based phase mask method. The surface relief grating topography (grating amplitude and grating constant) is investigated in dependence on the laser irradiation parameters (fluence and irradiation dose) yielding some information relevant for the ablation and grating formation mechanism.

Grating structures are fabricated in polymer substrates by femtosecond- (fs-) IR-laser radiation. Several sorts of polymer are employed as polymeric basic material for the grating manufacture: polymethylmethacrylate (PMMA), fluorinated PMMA, poly-N-methyl methacrylimide (PMMI), polycarbonate (PC), polyimide (PI) and polysiloxane. Surface and volume gratings are fabricated by positioning the focus of the fs-laser beam directly on the surface or inside the volume of the polymeric substrate, so by the right choice of the irradiation parameters the irradiated zone of the substrate is ablated, modified or carbonized. The sample is moved according to a scanning algorithm in order to generate the grating structure. The diffraction efficiency of the grating samples is measured by a HeNe laser. Some proposals are given for the mechanism of the grating generation.

The refractive index of some polymers can be locally increased in a controllable way by UV-excimer laser irradiation. Thus by mask lithographic methods integrated-optical waveguiding and dispersive structures are generated in the surface of a planar polymer chip. By this way a polymeric Bragg sensor component in integrated-optical form was fabricated by the UV-light of an excimer laser. The functional properties of the polymeric Bragg sensor have been investigated in dependence on the irradiation parameters and the temperature.

In this treatment method laser radiation, which is guided from a co-axially expanding liquid jet-stream, locally initiates on a metal surface a thermochemical etching reaction, which leads to selective material removal. Time-resolved measurements of the electrical potential were correlated with the specific processing parameters to identify conditions for stable and enhanced chemical etching reactions. The chemical etching reaction was additionally influenced by an electrical field. Depending on its polarity a significant increase in the etch rate or improvement of the treatment quality was observed. Exemplary, the fabrication of superelastic micro-grippers prepared by cutting of temperature-sensitive shape memory alloys is shown.

In this paper the development of a new plasma-CVD method for synthesis of PC-diamond coatings in air is presented. The method does not require any vacuum or reaction chamber and is based on plasma-CVD processes taking place in a photon-initiated stationary plasma in the open-air atmosphere maintained in the electromagnetic optical field of a high-power cw-CO 2 laser radiation. To use this plasma as an activation source for the CVD process with different gas precursors, a special photon plasmatron operating in air has been designed and constructed. The high temperature in the photon-initiated plasma (15 000–20 000 K) as well as the high pressure (≥1 atm) of the precursor gases, are prerequisites for a high-rate synthesis of PC-diamond coatings. For this purpose, different gases like Ar, CO 2 , CH 4 , H 2 , N 2 and their mixtures have been used. The properties of the deposited coatings in dependence on the experimental conditions have been investigated with SEM, EDX, AUGER and RAMAN techniques. With this new technology uniform and continuous PC-diamond films on molybdenum, Si and cemented carbides have been locally deposited onto an area of approximately 2 cm 2 with a deposition rate of up to 2 μm/min for the present. With optimisation of the process, a further significant increase in deposition rate can be expected.

Simultaneous UV-laser irradiation during the deposition of DLC films has been found to significantly influence the growth process and to favourably modify the film properties. The influence of the spectral and energetic parameters of laser radiation was investigated with respect to the optical, structural and mechanical properties of DLC films. Detailed investigations on the mechanism of laser-induced structural transformations in DLC films are presented, as studied by Raman spectroscopy. Further, the characteristic peak for the nanocrystalline diamond phase at 1140 cm −1 was evident for irradiated films. Noteworthy is the increase in film microhardness with increasing energy of the deposited carbon ions with a simultaneous reduction in internal stresses, caused by photolytically induced modification of the film structure by UV-laser radiation. As a result, hard (up to 30 GPa) and thick (up to 3 μm) defect-free DLC films without cracks have been synthesized.

The processing variables in Pulsed Laser Deposition technique such as deposition rate, ion concentration and kinetic ion energy are strongly determined by the laser parameters, especially the laser wavelength and the laser power density. In this paper, results are presented on the investigation of the pulsed plasma fluxes produced by six different lasers with wavelength ranging from the UV (248 nm) to the IR (10.6 m). These results have been used to study the influence of the plasma parameters on the formation of alumina (Al2O3) and multicomponent metal alloy (Cu–Mn–Ni) thin films. Oxide and metal films with a very smooth, nearly defect- and droplet-free surface could be synthesized by the UV laser radiation. Also, a wavelength dependence of the surface morphology of the deposited films was found out. Chemical composition, microhardness and elastic modulus of the films were determined and correlated with the deposition conditions.

laser maintenance of a stationary optical discharge in a gas stream, exhausting over a substrate into the air (laser plasmatron). Nano- and polycrystalline-diamond films were deposited on tungsten substrates from atmospheric-pressure Xe(Ar):H2:CH4 gas mixtures at flow rates of 2 ?/min. A 2.5-kW CO2 laser focused beam produced plasma. The deposition area was about 1 cm2 and growth rates were up to 30–50 μm/h. Peculiarities and advantages of laser plasmatrons are discussed.

This paper presents the main results of an extensive study on the influence of the spectral. energetical and temporal laser parameters on the formation of plasma fluxes and the deposition process of alumina (Al 2 O 3 ) thin films. For the experiments, four different pulsed lasers were used - an excimer laser, two Nd:YAG lasers with a specific pulse shape in the nanosecond and millisecond range, respectively, and a TEA-CO 2 laser. It was shown, that the plasma parameters (particle flux density. plasma composition, degree of ionisation, energy distribution of the ions) and the properties of the deposited films (surface morphology) strongly depend on the laser parameters, especially on the laser wavelength. In order to better control the properties of the plasma fluxes and to avoid some disadvantages arising from the use of a single laser, a new technique was developed consisting of the synchronous superposition of pulses of two lasers on the target. By the combination of different wavelengths and by a precise adjustment of the delay between the pulses it is possible to match the plasma parameters like ion energy. plasma density and temporal shape of the plasma fluxes on some specific requirements of the deposited film system and to increase the energetical efficiency of the particle fluxes in the process of film formation on the substrate.

In this paper the first results of an experimental study of the dependence of some plasma parameters (plasma density, degree of ionisation, energy distribution of the ions) on the laser parameters (light flux density, wavelength) for two laser types (TEA-CO 2 and excimer laser) are presented. A special experimental method has been developed for absolute measurement of some plasma parameters, such as plasma flux density, ion energy, multicharge ion content and ionization degree. The results obtained show the possibility to control the parameters of plasma fluxes over the deposition conditions and herewith to control the properties of the deposited films.

Laser-induced wet chemical etching of titanium and stainless steel foils in phosphoric and sulphuric acid was investigated. Focussing of cw-Nd:YAG laser radiation at power levels up to 7 W to a focal spot diameter of about 25 μm resulted in chemical etching of grooves at speeds up to 90 μm s −1 and cutting of foils at velocities of 10–50 μm s −1 . Aspect ratios up to 2 were obtained. Fabrication of free-standing microstructures is demonstrated.

The surface properties of some polymers in relation to physicochemical affinity to similar or other materials (adhesion, moistening, adsorption etc.) are very poor, which then limits their use in specific technical applications. To improve the surface properties in this field a mechanical, wet-chemical or plasma treatment of the work pieces is applied. Most of these methods, however, have some disadvantages as, for example, alteration of the surface morphology, poor controllability and pollution of the environment. These are the reasons why improvement of these technologies are the subject of current research. One relatively new way to change the surface conditions of polymers is the use of excimer lasers. Recent results are presented concerning the interaction of UV-laser radiation with polymers and resulting photolytical modification and activation (adhesion, morphology) of their surface. These results show that under certain conditions polar groups are observable. On the basis of such activati...

Laser-assisted chemical etching of Co, Cr, Cu and Ti w;is investigated using aqueous solutions of phosphoric acid and KOH at different concentrations. Thin metal films on glass substrates and thin foils were etched upon irradiation with a focussed Ar-laser operating at 514 nm and an output power of about 1 W. Static etch rates of the order of 10 pmμmsol;s were obtained at measured background etch rates less than 103 nm/s. The influence of the laser power on the etch rate suggests dominating thermally activated etch reactions. Due to the thermal nature of the etch process etched lines of about two times smaller width than the estimated laser spot diameter could be obtained. Etching of lines in thin Ti films on glass subsu'ates was performed by laser direct writing at speeds of about 1 mm/s and a laser power of about 0.3 W. Cutting of thin Ti foils was obtained at cutting velocities of about 30 um/s and a power of 0.8 W. The width of the etched lines was found to be controlled by laser power and wr...

In this paper we report on a new method for the generation of shaped holes by dynamical variation of the beam shape with a special optical system. It is based on using a q-switched Nd:YAG laser with 100 ns pulses at a wavelength of 1064 nm and an optical setup producing a photon tube. By variation of the beam divergence the shape of the photon tube can be variably modified. The optical system consists of a specially designed Galilean telescope and a focusing objective. The beam divergence can be changed in-situ by the Galilean telescope while processing. This enables to control diameter, length and angle of the photon tube. Shaped controlled structures are processed applying in-situ different optical fields which have been previously defined by simulations including aberrations and diffraction effects. As an example, the variable beam shaping resulted in through-going cylindrical bores as well as such ones with a defined conical inlet with respect to its taper angle and depth. Taper angles between 1 and nearly 50 degrees were realized by varying both the beam divergence and laser power. Furthermore, the variable beam shaping leads to improved and almost debris-free machining efficiency.

Laser-induced technological chemical processes can significantly contribute to the development of new methods for micro treatment of materials and hence to the broadening of the application spectrum of laser microtechnology. In this paper three typical laser-activated chemical technological methods in liquids, gases and solids and their possible applications are presented and discussed: (1) Laser-induced liquid-phase jet-chemical etching of metals. In this method, laser radiation which is guided from a coaxially expanding liquid jet-stream initiates locally on a metal surface a thermochemical etching reaction, which leads to a selective material removal at high resolution ( 2 laser radiation. This method allows synthesis of thin-film coatings in the open-air atmosphere without using vacuum or reaction chamber; (3) Laser-induced photochemical modification of the optical properties of polymers. This method is based on the local controllable change of the polymer structure leading to modification of the refractive index in the treated area. By numerous independently adjustable laser radiation parameters, for instance wavelength and irradiation dose, the modification process can be controllably driven in order to generate desired functional properties.

By UV-laser irradiation the refractive index of some polymers can be locally increased in a controllable way. So by mask lithographic methods integrated-optical waveguiding and dispersive structures can be generated in the surface of a planar polymer chip. Thus a polymeric Bragg-sensor component in integrated-optical form was fabricated by the UV-light of an excimer laser. The surface morphology and optical-functional properties of the polymeric Bragg sensor component have been examined especially in dependence on the irradiation parameters and the temperature. The investigations yield the suitability of the Bragg-sensor for the measurements of temperature and deformation. For the realization of a passive fiber-chip coupling for the integrated-optical components a new technology has been developed and tested. The precise control and high-resolution ablation capability inherent in excimer laser machining make it ideally suited for creating grooves for passive alignment of optical fibers to planar channel waveguides.

Laser-induced technological chemical processes can significantly contribute to the development of new methods for micro treatment of materials and hence to the broadening of the application spectrum of laser microtechnology. In this paper three typical laser-activated chemical technological methods in liquids, gases and solids and their possible applications are presented and discussed: (1) Laser-induced liquid-phase jet-chemical etching of metals. In this method, laser radiation which is guided from a coaxially expanding liquid jet-stream initiates locally on a metal surface a thermochemical etching reaction, which leads to a selective material removal at high resolution ( 2 laser radiation. This method allows synthesis of thin-film coatings in the open-air atmosphere without using vacuum or reaction chamber; (3) Laser-induced photochemical modification of the optical properties of polymers. This method is based on the local controllable change of the polymer structure leading to modification of the refractive index in the treated area. By numerous independently adjustable laser radiation parameters, for instance wavelength and irradiation dose, the modification process can be controllably driven in order to generate desired functional properties.

In this article the fabrication of grating structures in the surface of planar polymer chips by the phase mask method is discussed. By this way surface relief gratings (SRG) and bragg-structures can be generated by UV-laser irradiation. Especially the topographical surface properties of the gratings have been examined. Potential applications are the field of optical sensor and information technology.

In this treatment method laser radiation, which is guided from a coaxially expanding liquid jet-stream, locally initiates a thermochemical etching reaction on a metal surface, which leads to selective material removal at high resolution and quality of the treated surface as well as low thermal influence on the workpiece. Electrochemical investigations were performed under focused laser irradiation using a cw-Nd:YAG laser with a maximum power of 15 W and a simultaneous impact of the liquid jet-stream consisting of phosphoric acid with a maximum flow rate of 20 m/s. The time resolved measurements of the electrical potential difference against an electrochemical reference electrode were correlated with the specific processing parameters and corresponding etch rates to identify processing conditions for temporally stable and enhanced chemical etching reactions. Applications of laser-induced liquid-phase jet-chemical etching in the field of sensor technology, micromechanics and micrmoulding technology are presented. This includes the microstructuring of thin film systems, cutting of foils of shape memory alloys or the generation of structures with defined shape in bulk material.

Institute ofAppliedBeam Technology, Kiagenfurter Sfr 2, 28359 Bremen, GermanyE-mail: metev@bias.deLaser-induced technological chemical processes can significantly contribute to the development ofnew methods for micro treatment of materials and hence to the broadening of the application spectrumof laser microtechnology. In this paper three typical laser-activated chemical technological methods inliquids, gases and solids and their possible applications are presented and discussed: 1) Laser-inducedliquid-phase jet-chemical etching of metals. In this method, laser radiation which is guided from a co-axially expanding liquid jet-stream initiates locally on a metal surface a thermochemical etching reac-tion, which leads to a selective material removal at high resolution (< 1 jim) and quality of the treatedsurface; 2) Local photon-plasma induced synthesis of thin film coatings. This technological method is

In this paper some recent results are presented about the photochemical modification of polymers by UV-laser-irradiation which leads to a controllable and local change of the refractive index in the irradiated area of the polymer surface. The exact modification mechanism and its relation to the modified refractive index have been investigated on the basis of PMMA used as a UV-modifiable model polymer with good optical quality. This new UV laser-assisted technology for photochemical modification of the optical properties of UV-modifiable polymers like PMMA or PMMI and their fluorinated derivates permits the fabrication of a wide range of integrated-optical components like strip waveguides, power splitters, (Mach-Zehnder-)interferometers, Bragg gratings and other dispersive structures. These integrated-optical elements are crucial for the realization of dispersive components like WDM or AWG, which have a wide application in the optical sensor and information technology. The optical and functional properties like loss rate or mode propagation of some selected integrated-optical components have been investigated and are discussed in this article.

A novel technique for CVD synthesis of materials, that does not demand a vacuum chamber and provides high deposition rates, have been developed. It is based on CW CO2-laser maintenance of a stationary optical discharge in a gas stream, exhausting over a substrate into the air. Nano- and polycrystalline diamond films were deposited on tungsten substrates from atmospherics pressure Xe(Ar):H2:CH4 gas mixtures at flow rates 2 1/min. 2,5 kW CO2-laser focused beam produced plasma. Deposition area was about 1 cm2 and growth rates up to 30-50 micrometers /hour. Peculiarities and advantages of laser plasmatrons are discussed.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

One of the most stable tendencies of modern techniques — it is tendency to miniaturization. Semiconductor transistors invention led to new directions in information processing and to the appearance of microelectronics.

Laser radiation provides a unique tool for various micromachining methods using either physical (1) or chemical (2) processes resulting in material removal. Physical processes for material removal, however, are often accompanied by redeposition of evaporated mater near the laser interaction region. Especially in the case of metals a temporary molten phase seems to be unavoidable (1). Its resolidification results in a reduction of the accuracy of the treatment (surface roughness, deviation from the desired geometry). In such cases material removal by localized chemical etching reactions can significantly increase the accuracy of laser micromachining, providing some additional means for direct 3D-micromachining of metals. In comparison to laser-induced physical processes for material removal, however, chemical processes in many cases are expected to be of lower processing speeds, as the amount of the removed material depends not only on laser power but also on the rate of mass transport of incoming and outgoing reactands as well as on the rate of elementary chemical reactions. A high density of reactands, as in liquids, and a pronounced exchange of reactands, i. e. induced by convection, are prerequisites for high chemical reaction rates. In addition, processing in an aqueous environment is accompanied by an efficient cooling of the sample’s surface.

This paper presents the main results of an experimental study of the dependence of some important plasma parameters (plasma flux density, multicharge ion content, degree of ionization, energy distribution of the ions) on some laser parameters (light flux density, wavelength) for two laser types (TEA-CO2- and excimer laser). A special experimental method has been developed for an absolute and simultaneous measurement of the plasma parameters. The results obtained show the possibility to control the parameters of plasma fluxes over the deposition conditions and herewith to control the properties of the deposited films.

Laser-induced wet chemical etching of Co, Cr, Cu and Ti in aqueous solutions of potassium hydroxide and phosphoric acid was investigated using an Ar-laser operating at 514 nm. Etching of thin metal films on glass substrates and metal foils was obtained at static etch rates up to about 10 micrometers /s at an incident laser power of about 1 W. Measured background etch rates were less than 10 -5 nm/s. EDX-analysis of Ti foils etched in phosphoric acid revealed no enrichment of phosphorous near the laser interaction zone. An observed exponential dependence of static etch rates on laser power is interpreted in terms of dominating thermally activated chemical reactions at the metal surface. Laser direct writing of thin transparent lines in metal films on glass was obtained at writing velocities of about 1 mm/s and a laser power of about 0.3 W. Smallest line widths of about 3 micrometers were obtained which are about a factor of two smaller than the laser focal spot diameter. This observation is in agreement with dominating thermally activated surface reactions. Cutting of thin Ti foils (25 micrometers ) was obtained by laser chemical etching at a velocity of about 30 micrometers /s and an incident laser power of about 0.8 W. Wall angles between 70 and 80 degree(s) were found to depend on experimental parameters.

In the paper the results of a theoretical investigation of the growth process of laser-plasma deposited thin films are discussed. A kinetic approach has been used to establish direct relation between experimental conditions (laser flux density, substrate temperature) and film properties (thickness, structure). The results of some experimental investigations of the deposition process are presented confirming the general conclusions of the developed theoretical model.

In the paper the results of a theoretical investigation of the growth process of laserplasma deposited thin films are discussed. A kinetic approach has been used to establish direct relation between experimental conditions (laser flux density substrate temperature) and film properties (thickness structure) . The results of some ex perimental investigations of the deposition process are presented confirming the general conclusions of the developed theoretical mo del. 1 .© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Some results are presented concerning the laser-induced photochemical enhancement of the adhesive bonding strength between polypropylene (PP) and adhesives on a resinous basis. The mechanism of the laser-activated processes is discussed. At some conditions a bonding strength enhancement of more than 5 times has been achieved.

The paper presents some preliminary results on the preparation of BeO thin film exodetectors by laser evaporation: the influence of various parameters (temperature, impurity content) on the TSEE (thermally stimulated exoelectron emission) and OSEE (optically stimulated exoelectron emission), as well as the dosimetric properties of the exodetectors, have been investigated.

In the paper the results of a theoretical investigation of the nucleation and growth process of laser-plasma deposited thin films are presented. A kinetic approach has been used to establish direct relation between experimental conditions (laser flux density, substrate temperature) and film properties (thickness, structure). It has been shown that some qualitative experimental investigations of the deposition process confirm the general conclusions of the developed theoretical model.

Formation de couches minces PbTe a l'aide d'un faisceau laser pulse Nd et etude de leurs caracteristiques: epaisseur, composition, structure, par microsonde et diffraction electroniques

One of the most effective applications of the laser technology is in the microelectronics. Today lasers are widely used in two main technological processes of the microelectronics (Fig. 1).

There is increasing interest in understanding the photoinduced decay channels of simple organometallic complexes, in particular those of metal carbonyls. These complexes are noted for their high photochemical instability since the energy of an absorbed photon in the near uv or uv is sufficient to break several of the weak metal-ligand bonds. Possible applications are therefore wide spread, ranging from the favourable production of free atoms and atomic clusters, their utility as convenient model systems in photocatalysis, to their advantageous properties for laser induced metal deposition.

A laser evaporation technique has been applied to preparation of BeO thin films, and some results on the preparation conditions have been obtained. TSEE and OSEE from the films thus produced have been studied to clarify their emissive and dosimetric properties (sensitivity, dose linearity, fading) used as exodosemeters.