A UV Direct-Write Approach for Formation of Embedded Structures in Photostructurable Glass-Ceramics

Abstract

Photostructurable glass-ceramics are a promising class of materials for MEMS devices. Previous work micromachining these materials used conventional photolithography equipment and masking techniques; however, we use direct-write CAM tools and a pulsed UV laser micromachining station for rapid prototyping and enhanced depth control. We have already used this class of materials to build components for MEMS thrusters, including fuel tanks and nozzles: structures that would prove difficult to build by standard microfabrication techniques.A series of experiments was performed to characterize process parameters and establish the processing trade-offs in the laser exposure step. The hypothesis that there exists a critical dose of UV light for the growth of an etchable crystalline phase was tested by exposing the material to a fluence gradient for a variety of pulse train lengths, and then processing as usual. By measuring the dimensions of the etched region, we were able to determine the dose. We found that the dose is proportional to the square of the per-pulse fluence. This has allowed us to create not only embedded structures, but also stacked embedded structures. This also implies that we can embed tubes and tunnels with a single exposure inside a monolithic glass sample. We feel that this technique has promise for a number of applications, including microfluidics.

Three‐dimensional femtosecond laser micromachining of photosensitive glass for biomicrochips

“…Although internal microstructuring of the photosensitive glass is possible even by a nanosecond-pulsed UV laser [43][44][45][46], the multiphoton absorption by the fs-laser irradiation allows for easier fabrication of true and complicated 3D microstructures with higher spatial resolution, in particular, in a direction parallel to the laser-beam propagation. This is the reason and motivation for using the fs-laser in this study.…”

“…15 shows a schematic illustration of the microoptical device in which two waveguides were integrated with a micromirror and a microlens in a single glass chip. In the fabricated structures, one waveguide (waveguide I) of 5 mm length was connected to a micromirror with an angle of 45 procedure are described elsewhere [30]). Thus, the nearfield focal spot profile was observed.…”

Laser Processing Architecture for Improved Material Processing

“…Specifically, we have investigated the efficiency and mechanisms of the photoexcitation process [52,53], the sensitivity of the nascent chromophore to various exposure wavelengths [44,[54][55][56], the corresponding phase separation and chemical solubility of the laser-exposed material [52,53], the applicability of the photoexposure and chemical etching for 3D volumetric patterning and structure fabrication [53,[56][57][58][59], and the selective material properties that can be influenced by the photon dose [43,53,56]. A fundamental goal of our research is to develop laser pulse scripts that induce specific material transformation processes during coordinated direct-write patterning, and to acquire a detailed understanding of the underlying photophysics and chemistry that relates to these laser-induced conversion processes.…”

3D features of modified photostructurable glass–ceramic with infrared femtosecond laser pulses

“…Excimer and Nd: YAG lasers with nanosecond pulses and UV wavelengths, as well as femtosecond pulsed lasers with infrared wavelengths have been used for Foturan microfabrication [5][6][7][8][9][10].…”