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Laser-induced backside wet etching of fusedsilica plates using an aqueous solution of naphthalene-1,3,6trisulfonic acid trisodium salt (Np(SO[sub 3]Na)[sub 3]) is reported. A KrF excimer laser was employed as a light source. The etch rate varied greatly with the concentration of the solution and the laser fluence. For lower concentration solutions, the etch rate increased linearly with laser fluence. For highly concentrated solutions, however, the etch rate increased abruptly at higher fluence. Well-defined line-and-space and grid micropatterns were fabricated using a low etch rate. The etched surface was as flat as the surface of the virgin plates and the etched pattern was free of debris and microcracks. The formation and propagation of shockwaves and bubbles in the solution during the etch process were monitored. High pressure, as well as the high temperature generated by the photothermal process, plays a key role in the etching process. [ABSTRACT FROM AUTHOR]

By a laser-induced backside wet etching method using a pyrene/acetone solution, a fused silica plate was etched upon irradiation with a conventional XeCl excimer laser. The etch rate was about 50% lower than that obtained with a KrF excimer laser under the same experimental conditions. The threshold fluence for etching was estimated to be below 0.5 J cm−2 and a typical etch rate was around 10 nm pulse−1 at a fluence of 1 J cm−2. After producing the sample having the 10 μm lines and space by irradiation with the first 200 pulses, the second 400 pulses were irradiated to the target sample rotated at right angle. As a result, a square dotted pattern was given without damages for the first etched pattern. Micrographs of the etched surfaces show that this process is a remarkably gentle process free from crack and debris, and favorable for microcrack-free etching of transparent materials. [Copyright &y& Elsevier]

Abstract. In order to control both molecular structures and molecular orientation simultaneously, we investigated organic molecular beam deposition combined with a laser-induced photochemical reaction. Bis(ethynylstyryl) benzene (BESB) films of trans,trans-isomer were deposited by this new method. The cis,cis-molecules were sublimed and cis-to-trans photoisomerization was conducted upon KrF excimer laser irradiation (lambda = 248 nm) in this process. The laser irradiation after and during the deposition at the substrate temperature of 25 Celsius yielded amorphous films. In contrast, the growth of well-oriented crystalline films was achieved upon the laser irradiation during the deposition at the substrate temperature of 60 Celsius. At this substrate temperature only the trans,trans-molecules were 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 proceeds favorably due to the surface migration of the trans,trans-isomer and the absence of the cis,cis-isomer. It was thus found that simultaneous progress of the laser-induced isomerization and the deposition caused the growth of the well-oriented crystalline films of trans,trans-BESB. [ABSTRACT FROM AUTHOR]

To clarify the initial stage of laser-induced backside wet etching, we directly measured transient pressure upon laser ablation of toluene under KrF excimer laser irradiation by using a fast-response pressure gauge. The propagation time of the pressure peak to the gauge agreed well with the time for the shock wave to reach the gauge on time-resolved images. The peak pressure P decreased slowly with increasing distance d: P=30.4 MPa for d=100 μm to P=11.1 MPa for d=1000 μm at a fluence F=1.0 J cm-2 pulse-1. The initial pressure, estimated to be of the order of 10–200 MPa, impinges on a transparent plate and contributes to the etching. [ABSTRACT FROM AUTHOR]

The preparation of TiO2, In2O3, SnO2 doped In2O3 (ITO) and PbZr0.5Ti0.5O3 (PZT) films have been investigated by the metallorganic (MO) laser photolysis. TiO2 anatase phase was successfully obtained from Ti-2-ethylhexanolate by a two-step irradiation method, while rutile was formed from TiOacac under the same irradiation conditions. In2O3 and ITO films were crystallized by ArF irradiation above the laser fluence of 10 mJ/cm2. The resistivity of the In2O3 film irradiated by further ArF laser in a vacuum and air atmosphere was 2.2×10−2 and 2.2×10−1 Ω cm, respectively. The lowest resistivity of the ITO film irradiated by the ArF laser in a vacuum was 6.0×10−4 Ω cm. Epitaxial PZT film on a SrTiO3 substrate was successfully obtained by MO laser photolysis. [Copyright &y& Elsevier]

We have investigated the onset of surface optical breakdown on a polished, synthetic silica glass under KrF excimer laser irradiation. With increasing laser fluence, a transient, localized luminescence is often observed. If the fluence is increased further, the luminescence reappears and grows gradually more intense with continued exposure. Subsequent examination of damaged surfaces show small craters, about 1 μm in diameter, in the damaged region. Surfaces damaged by single laser pulses at still higher fluences show similar morphologies, suggesting that the same defects or flaws are responsible for damage under multiple pulse and single pulse conditions. [Copyright &y& Elsevier]