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Variation in the etch rates for fabricating single deep microtrenches by laser-induced backside wet etching (LIBWE) employing a KrF excimer laser and acetone solution of pyrene is investigated. Microtrenches with widths of 5, 8, 10, 15, and 20 μm, a length of 1 mm, and depths up to 90 μm were fabricated with a fluence of 1.3 J/cm², a pulse repetition of 80 Hz, and various pulse numbers. Special care was directed to maintaining in-focus conditions for etching. In the fabrication of 5-μm-wide microtrenches, etch rates of 5.3 nm/pulse evaluated for trenches with depths of less than 4 μm increased by a factor of 2.55 to 13.5 nm/pulse when the trenches became deeper than 16 μm. Such variation in the etch rate reduced with width and became negligibly small for 20-μm-wide microtrenches. Based on a similar dependence on width, the variation in etch rate with depth can be related to the size effect observed in LIBWE. As a factor causing the size effect as well as the variation in etch rate with depth, the interaction between the laser-heated surface and the solution in an early time region of the laser-induced phenomena is proposed. [ABSTRACT FROM AUTHOR]

Flexible and rapid preparation of FeSi2 microdots and indium tin oxide (ITO) microstructure patterns was performed using laser-induced forward transfer with a nanosecond high-frequency diode-pumped solid-state laser/galvanometer-based point-scanning system. Different types of source materials, i.e., FeSi2 and ITO, were used to explore the materials dependence of transfer. FeSi2 spheres with a lateral diameter of 5.5 μm were successfully arrayed on a micrometer scale. Sub-spot transfer was achieved, and we refer to this as laser-induced dot transfer (LIDT). In the case of ITO, although the transferred shape is flower-like rather than spherical, site-controlled transfer was achieved. The LIDT technique is useful for integrating functional micro-patterns with sub-spot resolution under room-temperature atmospheric conditions. [ABSTRACT FROM AUTHOR]

An indirect laser processing, laser-induced backside wet etching (LIBWE) is one of effective techniques for flexible laser-direct-write (LDW) type micromachining of transparent materials. Micromachining by LIBWE employing a diode-pumped solid state (DPSS) green laser and a galvanometer-based point scanning system was examined with employing organic dye solution and liquid metal as laser-absorbing media. LIBWE using liquid metal absorber showed smaller threshold pulse energies for etching (9.1 μJ/pulse) than that using organic dye solution (33 μJ/pulse). Different morphologies of etched surfaces were observed for different laser-absorbing media, indicating different mechanisms involved in the etching processes. The laser-induced dynamic phenomena were investigated by means of transient reflection measurements. The different contribution of direct and indirect actions of laser pulses was indicated for LIBWE employing different laser-absorbing media. [ABSTRACT FROM AUTHOR]

Slanted microstructures were fabricated on silica glass by laser-induced backside wet etching (LIBWE) with gradual shift of the area irradiated by normal incidence. Slanted microtrenches with tilting angles up to about 30 degrees could be fabricated by lateral shift of the irradiated area with the speed of ∼5.0 nm·pulse-1 under the conditions showing the vertical etching with rate of 7.0 - 11 nm·pulse-1. Tilting angle could be controlled by the speed of lateral shift the irradiated area during the etching. Such structures were formed as a result of both lateral and vertical etching at the etch front. The trench structure fabricated by drastic shift of the irradiated area indicated that the etching of the sidewalls occurred at the area with height of around 400 nm. [ABSTRACT FROM AUTHOR]