An increase of industrial needs for micro-ablation and surface structuration using sub-picosecond laser working at high
repetition rate is required. In this context, new industrial lasers were recently commercialized for such a type of purpose.
The potential of a new industrial femtosecond laser source (Tangerine model from Amplitude Système) is investigated in
this work for different etching purposes. Our experimental results will be also compared to those obtained when using
Ti:Sa laser source, with the help of numerical simulations.
In this paper we propose a one step marking process using a high power near infrared fiber laser and diffractive optical elements or gratings as an alternative to traditional scanning systems. The impact of the gratings fill factor, the power level on the diffracted beams and the quality of the reconstructed images are studied. We present simulation results of gratings diffraction efficiencies, experimental observations of gratings and DOEs behaviour illuminated with a fiber laser beam. We demonstrate that the fiber laser, showing good beam quality, can be used with standard diffractive structures with interesting results.
Low-temperature polycrystalline silicon (poly-Si) is today a promising material allowing the production of large-area thin-film transistor (TFT’s) displays. High-performance poly-Si TFT’s are currently obtained using a pulsed excimer laser beam to crystallize the amorphous deposited silicon (a-Si) film on a glass substrate. The final quality of the poly-Si devices depends on several key parameters such as the laser energy density, the beam homogeneity and the number of laser shots. However, rapid quality control is needed to optimise and stabilize the crystallization process.
In this work, the micro structural evolution of the crystallized area with the laser annealing conditions and the formation in the Super Lateral Growth (SLG) region of large grain poly-Si have been investigated by interference microscopy. Phase Stepping Microscopy (PSM), which allows nanometric measurement of surface morphology, has been used to follow the annealing process in Si thin films on glass irradiated using a large area (~ 40 cm2) and long pulse duration (200 ns) excimer (XeCl) laser.
The results of the surface morphology obtained by interference microscopy and confirmed by Atomic Force Microscopy (AFM) attest to the PSM technique being one of the most interesting alternative ways that could be used for the calibration of the laser annealing process in an industrial environment.
The use of high-power pulsed excimer lasers, working in the nanosecond (ranging from 20 to 200 ns) duration regime, allows the deposition of a large amount of energy in very short times into the near surface region of amorphous silicon films deposited on glass. Under suitable conditions, the laser irradiation leads to the rapid melting of the a-si layer and its regrowth into polysilicon. In order to optimize the final quality of the poly-Si film and the formation of a large grained material through a so-called super-lateral-growth phenomenon, it appears necessary to control extremely carefully the surface melt dynamics of the laser processing, by developing a numerical simulation based on the resolution of the one-dimensional heat flow equation. It is demonstrated that the melting threshold, melt duration, depth of fusion and solidification velocity, are strongly dependent on the laser pulse duration, substrate temperature, thickness of the silicon and oxide (or nitride) barrier layers. These numerical analyses are also shown to be consistent with the experimental results.
Sol-gel coatings are finding increased applications in fields as diverse as traditional optical coatings (eg anti- and high-reflectance) and microelectronic devices. Following the deposition process heat treatment is required to densify or crystallize the films. The disadvantage of conventional heat treatment, by hot plate or oven, is the limit on temperature and time set either by the thermal stability of the materials or by interactions between film and substrate. A study has been made of the use of excimer lasers for heat treatment of PZT (PbZrO3:PbTiO3) sol-gel films, the main application being pyroelectric detector arrays.
Epitaxial Si1-yCy and Si1-x-yGexCy alloy layers are grown on monocrystalline silicon substrates by multiple energy ion implantation of Ge and C into single Si crystals followed by pulse excimer laser annealing. The properties of the alloy layers are determined precisely using spectroscopic ellipsometry (SE), x-ray diffraction (XRD) and Rutherford backscattering (RBS) techniques. We show that annealing energy densities higher than 2 J/cm2 result in monocrystalline epitaxial layers with low quantity of defects. The lattice contraction due to the carbon inclusion increases with the implanted C concentration up to about 1.1%. For higher values a more complex behavior is observed with partial (or total) relaxation of the layer and/or carbide formation. With optimized condition, the growing of pseudomorphic epitaxial layers, from group IV semiconductor alloys was successful on large areas thanks to the high power excimer laser developed at SOPRA (1 J/cm2 over 40 cm2 in one pulse).
Si1-yCy and Si1-x-yGexCy layers were grown by multiple energy ion implantation of Ge and C into single crystal Si followed by pulsed excimer laser induced epitaxy. The properties of the alloy layers obtained by this technique, in terms of film crystallinity, Ge and C redistribution and substitutional incorporation, strain formation and relaxation, SiC precipitation and C- induced band gap modification are demonstrated to depend strongly on both ion implantation and laser processing conditions. The growing of large area pseudomorphic epitaxial alloys of group IV semiconductor elements, using the high energy beam excimer laser (up to 1 J/cm2 per pulse over 40 cm2) developed by SOPRA for industrial applications, is described.
In this work, Si1-yCy and Si1-x-yGexCy alloy layers were grown by multiple energy ion implantation of Ge and C into single crystal Si followed by pulsed excimer laser induced epitaxy. The properties of the alloy layers obtained by this technique, in terms of film crystallinity, Ge and C redistribution an substitutional incorporation, strain formation and relaxation, SiC precipitation, were demonstrated to depend strongly both on ion implantation and laser processing conditions. The growing of pseudomorphic epitaxial layers, from group IV semiconductor alloys, using the very high energy and large area beam (up to 1 J/cm2 per pulse over 40 cm2) excimer laser developed by SOPRA, for mass production is reported for the first time.
In this paper, the preparation of SiGe films grown onto amorphous or single crystal substrates by pulsed excimer laser crystallization of heavily Ge implanted silicon is proposed as an alternative to classical MBE and CVD techniques. Processed films were characterized by ions (channeling-RBS) and optical (Raman) techniques.
Silicon oxide, oxynitride and nitride films are deposited at low temperature (<EQ 450 degree(s)C) by pulsed ArF excimer laser ablation from silicon, silicon monoxide, fused silica and silicon nitride targets, performed under vacuum and in oxygen atmosphere. We investigate in this paper the specific influence of laser fluence, target materials, substrate temperature and oxygen pressure on the composition and final properties of SiOxNy grown layers. The process conditions are optimized in order to deposit good quality silicon oxide and silicon nitride thin films.
In this work, we detail the basic mechanisms and potential applications of the Laser Induced Forward
Transfer (LIFT) for the rapid deposition and patterning in a clean environment, of high Tc superconducting thin
films. With the LIFT technique, a stoichiometric oxide superconductor compound is initially deposited in a thin
layer on an optically transparent support. By irradiating, under vacuum or in air, this precoated layer with a
strongly absorbed single laser pulse through the transparent support, we are able to remove the film from its
support to be transferred onto a selected target substrate, held in contact or close to the original film. The
mechanisms for transferring YBaCuO and BiSrCaCuO thin films, with a pulsed UV excimer laser are described
using a thermal melting model based on the resolution of the heat flow equation. The various possibilities given
by the LIFT technique for patterning high Tc films (mask and direct patterning) are also examined.
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