High repetition rate femtosecond laser forming sub-10 µm diameter interconnection vias

Tan, Bo; Panchatsharam, Senthilnathan; Venkatakrishnan, Krishnan

doi:10.1088/0022-3727/42/6/065102

Cited by 34 publications

(17 citation statements)

References 28 publications

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“…On the example of Inconel 600, it can be seen that for very short exposure times (order of seconds), the debris cohesion with the target is low. On the other hand, material ablation with longer exposure time, as a rule, resulted in a stronger debris cohesion [9]. Profilometry comparing of two targets after 7 min exposure showed that in the case of WTi, the surrounding rim equals ≈ 1.25 µm, and for Inconel 600 it was ≈ 8 µm.…”

Section: Resultsmentioning

confidence: 97%

Surface Modification of Metallic Targets with Ultrashort Laser Pulses

et al. 2009

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Interaction of pulsed femtosecond Ti:sapphire laser (160 fs), operating at high repetition rate (75 MHz) at 800 nm, with nickel-based superalloy Inconel 600 and tungsten-titanium (WTi) target was studied. The WTi target was in form of thin film deposited on silicon substrate. Low laser fluence of maximum 50 mJ/cm 2 had modified the target surface during irradiation/exposure time of seconds or minutes. The radiation absorbed from the laser beam generates at the surface a series of effects, such as direct material vaporization, formation of clusters, etc. Morphological features of the targets can be summarized as: (a) intensive removal of material and crater appearance; (b) creation of nanostructures; (c) microcracking, etc. Ablation of Inconel 600 surface is effective, resulting in formation of holes with small diameter (≤ 10 µm) and relatively large depth (≤ 50 µm). In case of WTi target/thin film, the surrounding rim is not so expressed, and crater depths are lower. It can be concluded that the average laser power of the order of watts, pulse energies of the order of nanojoules and high repetition rates (MHz range) can successfully modify metallic materials.

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Section: Resultsmentioning

confidence: 97%

Surface Modification of Metallic Targets with Ultrashort Laser Pulses

et al. 2009

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“…Morphological changes induced by femtosecond laser on WTi/Si system, show their dependence on the laser beam characteristics such as pulse duration, pulse energy, laser peak power, irradiation time (exposure)/number of accumulated pulses and laser radiation frequency (Baurle, 2011;Cheng Jian et al, 2013;Tan et al, 2009;Campbell et al, 2007). In this work, attention was focused on the influence of LRF on the morphological and compositional changes of WTi/Si system.…”

Section: Resultsmentioning

confidence: 99%

Low and high repetition frequency femtosecond lasers processing of tungsten-based thin film

et al. 2014

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In this work we reported low and high repetition frequency femtosecond laser-induced modifications of tungsten-based thin film. The tungsten-titanium (WTi) thin film, thickness of 190 nm, was deposited by sputtering on single crystal Si (100) wafer. Irradiations were performed in air by linearly polarized and focused femtosecond laser beams with following parameters: (1) pulse duration 160 fs, wavelength 800 nm, laser repetition frequency (LRF) 75 MHz -high LRF, and (2) duration 40 fs, wavelength 800 nm, LRF of 1 kHz -low LRF. The results of femtosecond lasers processing of the WTi thin film revealed laser induced periodical surface structures (LIPSS) in the case of low LRF regime. LIPSSs were formed with different periodicity and different orientation to the laser polarization at the surface: micro-scale LIPSSs with orientation perpendicular to the laser polarization and nano-scale LIPSSs parallel and perpendicular to the laser polarization. After processing of the WTi/Si system in high LRF regime ablation and nanoparticles formation were registered.

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“…Initial studies in this field are focused on microvias generation, 1 microhole processing in steel and copper foils, 2 refractive index changes in transparent materials, 3 and laser ablation of microcavities. 4,5 In addition, the potential of the technology has been already demonstrated by means of specific machining examples, such as micropyramids and embossing tools.…”

Section: Introductionmentioning

confidence: 99%

High-rate laser microprocessing using a polygon scanner system

Loeschner

Schille

Streek

et al. 2015

Journal of Laser Applications

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This paper discusses results obtained in high-rate laser microprocessing by using a high average power high-pulse repetition frequency ultrashort pulse laser source in combination with an in-house developed polygon scanner system. With the recent development of ultrashort pulse laser systems supplying high average power of hundreds watts and megahertz pulse repetition rates, a significant increase of the productivity can potentially be achieved in micromachining. This permits upscaling of the ablation rates and large-area processing, gaining increased interest of the ultrashort pulse laser technology for a large variety of industrial processes. However, effective implementation of high average power lasers in microprocessing requires fast deflection of the laser beam. For this, high-rate laser processing by using polygon scanner systems provide a sustainable technological solution. In this study, a picosecond laser system with a maximum average power of 100 W and a repetition rate up to 20 MHz was used. In raster scanning using the polygon scanner, the laser beam with a focus spot diameter of 44 μm was deflected with scan speeds of several hundred meters per second. The two-dimensional scanning capability of the polygon scanner supplied a scan field of 325 × 325 mm. The investigations were focused on high-rate large-area laser ablation of technical grade stainless steel as well as selective thin film ablation from bulk substrates. By variation of the processing parameters laser fluence, as well as temporal and spatial pulse-to-pulse distance, their impact onto the ablation process was evaluated with respect to the ablation rate, processing rate, surface quality, and ablation efficiency.

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High repetition rate femtosecond laser forming sub-10 µm diameter interconnection vias

Cited by 34 publications

References 28 publications

Surface Modification of Metallic Targets with Ultrashort Laser Pulses

Surface Modification of Metallic Targets with Ultrashort Laser Pulses

Low and high repetition frequency femtosecond lasers processing of tungsten-based thin film

High-rate laser microprocessing using a polygon scanner system

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