Excimer laser machining for the fabrication of analogous microstructures (original) (raw)
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Fabrication of high-aspect-ratio microstructures using excimer laser
Optics and Lasers in Engineering, 2004
An excimer laser micromachining system is developed to study the ablation of high-aspectratio microstructures. The study examines the ablation efficiency, specifically, the impact of changing major laser operating parameters on the resulting microstructural shapes and morphology. The study focuses on glass, although results on silicon and aluminum are also included for comparison. In ablating grooved structures, the ablation depth has been observed to be linearly proportional to the operating parameters, such as the pulse number and fluence. The results specifically indicate that ablation at low fluence and high repetition rates tends to form a V-shaped cross-section or profile, while a U-shaped profile can be obtained at high fluence and low repetition rate. The ablation rate or ablated volume has then been quantified based on the ablation depth measured and the ablated profile observed. The threshold fluence has also been obtained by extrapolating experimental data of ablation rate. The extrapolation accuracy has been established by the good agreement between the extrapolated value and the one predicted by Beer's law. Moreover, a one-dimensional analytical solution has been adopted to predict the ablated volume so as to compare with the experimental data. The reasonable agreement between the two indicates that a simple analytical solution can be used for guiding or controlling further laser operations in ablating glass structures. Finally, the experimental results have shown that increasing the repetition rate favors the morphology of ablated surfaces, though the effect of repetition rate on ablation depth is insignificant. r
Fabrication of High-Aspect-Ratio Microstructures Using Excimer Lasers
An excimer laser micromachining system is developed to study the process in fabricating high-aspect-ratio microstructures. Specifically, the study experimentally examines process efficiency and the impact of changing major laser operating parameters on the resulting microstructural shapes and morphology. The materials considered in the study include glass, silicon, and aluminum. The ablation or micromachining rate has been observed to be strongly dependent on the operating parameters, such as the pulse fluence, number, and repetition rate. The results specifically indicate that ablation at low fluence and high repetition rate tends to form a V-shaped cavity, while a U-shaped cavity can be obtained at high fluence and low repetition rate. Additionally, the present study also indicates that a three-dimensional V-shaped cavity with large vertex angle can be formed by varying the focus depth of excimer laser. Materials of low thermal conductivity and low melting temperature are indeed more applicable to laser ablation.
Design and performance of an excimer-laser based optical system for high precision microstructuring
Optics and Laser Technology, 1998
We report on the design of an excimer-laser based system for high precision micromachining of spinnerets using a mask imaging technique. Both the illumination and imaging unit are optimized for specified demagnification ratios of 5 and 15, respectively. Detailed investigations were performed to measure the resolution, depth of focus and the sensitivity for the position accuracy of the substrate depending on illumination parameters. A special test mask for measuring the resolution in combination with a new definition of measurement procedure is used. SEM views of ablation results with high machining quality are presented. ß
Projection ablation of glass-based single and arrayed microstructures using excimer laser
Optics and Laser Technology, 2005
Ablation of single and arrayed microstructures using an excimer laser is studied. The single feature microstructures are fabricated for evaluating the ablation mechanism, threshold fluence, and associated material removing (ablation) rate. The morphology changes during ablation are investigated with the focus on the formation of the ablation defects, debris or recast. The possibility of removing these defects is also evaluated and demonstrated. The present study concentrates on the borosilicate glass, although ablation of polyimide and silicon are performed and discussed for comparison. Polyimide and silicon are the most popular polymer or semiconductor material used in the electronics industry. The arrayed microstructures are ablated to demonstrate the fact that, by repetition of a simple-patterned mask associated with synchronized laser pulses and substrate movement, arrayed and more complex structures can be cost-effectively manufactured. The potential applications of these arrayed microstructures are discussed and illustrated. A low-cost replication technique that uses the arrayed microstructure presently machined as the forming mold for making electroforming nickel microneedles is specifically presented. Finally, the potential areas of using excimer laser in micromachining of glass-based structures for future research are also briefly covered. r
Excimer laser micro machining: fabrication and applications of dielectric masks
Applied Surface Science, 2000
Excimer laser ablation is a versatile tool for the micro machining of various materials. Mask projection configurations employing dielectric masks allow fast and flexible high power processing. Due to their high reflectivity at the laser processing wavelength, these dielectric masks show superior performance concerning damage threshold and durability compared to chrome on quartz or metal stencil masks.
An alternative method of fabricating sub-micron resolution masks using excimer laser ablation
Journal of Micromechanics and Microengineering, 2004
In the work presented here, an excimer laser micromachining system has been used successfully to fabricate high-resolution projection and contact masks. The contact masks were subsequently used to produce chrome-gold circular ac electro-osmotic pump (cACEOP) microelectrode arrays on glass substrates, using a conventional contact photolithography process. The contact masks were produced rapidly (∼15 min each) and were found to be accurate to sub-micron resolution, demonstrating an alternative route for mask fabrication. Laser machined masks were also used in a laser-projection system, demonstrating that such fabrication techniques are also suited to projection lithography. The work addresses a need for quick reproduction of high-resolution contact masks, given their rapid degradation when compared to non-contact masks.
An increase in interconnection density, a reduction in packaging sizes and the quest for lowcost product development strategy are some of the key challenges facing micro-optoelectronics design and manufacture. The influence of high-density, small-sized products has placed significant constraints on conventional electrical connections prompting various fabrication methods, e.g. photolithography, being introduced to meet these challenges and ameliorate the rapidly changing demand from consumers. While high-power solid state lasers are fundamental to large scale industrial production, excimer laser on the other hand has revolutionised the manufacturing industry with high precision, easy 3D structuring and less stringent production requirements. Micro-structuring using excimer laser, best known as laser ablation, is a non-contact micro- and nano-machining based on the projection of high-energy pulsed UV masked beam on to a material of interest such that pattern(s) on the mask is transferred to the substrate, often at a demagnified dimension with high resolution and precision. The use of mask with desired patterns and beam delivery system makes the fabrication in this case accurate, precise and easily controllable. The first part of this chapter introduces the fundamentals of laser technology and material processing. In the second part, optical interconnects as a solution to ‘bottlenecked’ conventional copper interconnections is introduced with emphasis on excimer laser ablation of polymer waveguides and integrated mirrors. Key research findings in the area of optical circuit boards using other techniques are also briefly covered. Cite : Zakariyah, S.S. (2012). Laser Ablation for Polymer Waveguide Fabrication, Micromachining Techniques for Fabrication of Micro and Nano Structures, Mojtaba Kahrizi (Ed.), ISBN: 978-953-307-906-6, InTech, Available from: http://www.intechopen.com/articles/show/title/laser-ablation-for-polymer-waveguide-fabrication.
Femtosecond laser internal manufacturing of three-dimensional microstructure devices
Applied Physics A, 2015
Potential applications for three-dimensional microstructure devices developed rapidly across numerous fields including micro-optics, microfluidics, micro-electromechanical systems (MEMS), and biomedical devices. Benefiting from many unique fabricating advantages, internal manufacturing methods have become the dominant process for three-dimensional microstructure device manufacturing. This paper provides a brief review of the most common techniques of femtosecond laser three-dimensional internal manufacturing (3DIM). The physical mechanisms and representative experimental results of 3D manufacturing technologies based on multiphoton polymerization, laser modification, micro-explosion and continuous hollow structure internal manufacturing (CHSIM) are provided in details. The important progress in emerging applications based on the 3DIM technologies are introduced as well.
Optimization of laser micromachining process for biomedical device fabrication
The International Journal of Advanced Manufacturing Technology, 2015
Laser machining is commonly used for fabrication of medical devices with microscale features, including vascular stents, drug delivery devices, and scaffolds for tissue engineering with controlled pore size and porosity. The process can also be used to produce structured scaffolds for controlling cell growth, orientation, and location. Moreover, lasers may be used to fabricate complex channel nets in which cells are subsequently seeded or to pattern channels for microfluidic devices. Traditionally, these micro devices were fabricated using silicon substrates, but recently the use of titanium allowed to produce more robust devices at a reasonable cost. In particular, the high quality surfaces that can be obtained with laser machining reduce the liquid flow turbulence and avoid micro cavities formation, critical for bacteria proliferation. The present research reports the results of an investigation on the process capability of laser ablation to produce micro pockets fabricated on titanium sheet (0.5 mm thick). A first experimental campaign was designed for identifying a set of laser ablation cycles able to realize the micro pockets by changing the process parameters as scanning speed, laser power, q-switch frequency, loop number, and duty cycle. Moreover, a process optimization was executed in order to produce the pockets with a highly flat surface. The results were acquired by a confocal laser scanning microscope (CLSM) to obtain high-resolution images with depth selectivity and were analyzed with statistic methods for the identification of the best parameter configuration.
Micromachining of TiNi shape memory alloy by excimer laser ablation
Device and Process Technologies for MEMS and Microelectronics II, 2001
In this paper we investigate excimer laser micromachining of TiNi shape memory alloy using an image projection system as an alternative to photolithographic patterning. We report on the characteristics of material removal by KrF excimer laser induced ablation at 248 nm and the dependence of material removal rates on laser parameters such as fluence and pulse frequency. Fluences at the workpiece using a 10× projection lens were up to 2.5 J cm -2 with pulse repetition rates up to 100 Hz. Conventional chrome-on-quartz masks were used for pattern transfer. Material removal mechanisms and rates of material removal are compared with those observed during excimer laser micromachining of polymers and ceramics and limitations on achievable lateral and depth resolution explored. Data obtained by a variety of characterisation methods are correlated to assess the effects of laser induced damage.