Picosecond laser ablation of thin copper films

Jandeleit, Juergen; Urbasch, G.; Hoffmann, H. D.; Treusch, Hans-Georg; Kreutz, E. W.

doi:10.1007/bf01567638

Cited by 142 publications

(51 citation statements)

References 12 publications

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“…The appearance of pronounced traces of molten material in the picosecond irradiation regime 18,35,36,93 can also be related to the results of the simulations. While in the phase explosion regime the values of the maximum melting depth predicted in the two series of simulations are close to each other, the time of the melting and resolidification cycle is substantially longer in simulations performed with 50 ps laser pulses, providing the conditions for more significant redistribution of the melt within the laser spot (rim formation) and facilitating the expulsion of the melt.…”

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confidence: 54%

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Atomistic Modeling of Short Pulse Laser Ablation of Metals: Connections between Melting, Spallation, and Phase Explosion

2009

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The mechanisms of short pulse laser interactions with a metal target are investigated in simulations performed with a model combining the molecular dynamics method with a continuum description of laser excitation, electron-phonon equilibration, and electron heat conduction. Three regimes of material response to laser irradiation are identified in simulations performed with a 1 ps laser pulse, which corresponds to the condition of stress confinement: melting and resolidification of a surface region of the target, photomechanical spallation of a single or multiple layers or droplets, and an explosive disintegration of an overheated surface layer (phase explosion). The processes of laser melting, spallation, and phase explosion are taking place on the same time scale and are closely intertwined with each other. The transition to the spallation regime results in a reduction of the melting zone and a sharp drop in the duration of the melting and resolidification cycle. The transition from spallation to phase explosion is signified by an abrupt change in the composition of the ejected plume (from liquid layers and/or large droplets to a mixture of vapor-phase atoms, small clusters and droplets), and results in a substantial increase in the duration of the melting process. In simulations performed with longer, 50 ps, laser pulses, when the condition for stress confinement is not satisfied, the spallation regime is absent and phase explosion results in smaller values of the ablation yield and larger fractions of the vapor phase in the ejected plume as compared to the results obtained with a 1 ps pulse. The more vigorous material ejection and higher ablation yields, observed in the simulations performed with the shorter laser pulse, are explained by the synergistic contribution of the laser-induced stresses and the explosive release of vapor in phase explosion occurring under the condition of stress confinement.

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confidence: 54%

“…91 The complete melt expulsion has also been assumed in interpretation of experimental ablation characteristics obtained with longer, 40 ps, laser pulses, 35 when the contribution of photomechanical effects is likely to be negligible (see Section 3.4).…”

Section: On the Possible Contribution Of Melt Expulsion To The Ablatimentioning

confidence: 99%

Atomistic Modeling of Short Pulse Laser Ablation of Metals: Connections between Melting, Spallation, and Phase Explosion

2009

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“…To determine these fluence thresholds we studied the surface modifications generated at different laser fluences using the spot regresion method. 25 Briefly, when laser pulses posses a Gaussian spatial beam profile, the laser fluence, F, on the sample surface and the diameter D of the modified area are related by D 2 = 20 ln (F/Fth), where 0 is the 1/e 2 radius of the beam intensity distribution and the fluence is related to the pulse energy by F = E/π0 2 . From a plot of the D 2 versus lnE, Fth can be determined.…”

Section: Ablation Thresholdsmentioning

confidence: 99%

Femtosecond Pulsed Laser Deposition of Nanostructured CdS Films

et al. 2010

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In this work we report an investigation of the properties of nanostructured deposits obtained from femtosecond pulsed laser deposition of CdS sintered targets. Specifically, we address the effect of laser irradiation wavelength, laser fluence and substrate temperature (from 25 to 450 ºC). The composition of the deposits was characterized using X-ray photoelectron spectroscopy (XPS), their crystallinity by Xray diffraction (XRD) and the surface morphology was studied by environmental scanning electron microscopy (ESEM) and atomic force microscopy (AFM). It has been found that the smallest nanoparticles, with an average diameter of 25 nm and a narrow size distribution, together with particulates in the range 80-120 nm, are obtained at the shortest laser wavelength of 266 nm on room temperature substrates. Deposits do not contain microscopic droplets in any of the explored conditions. 3

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“…liu [1] and later adopted for thin film-removal by several other researchers. [2,3,4] the method involves generating single-pulse laser damage features at different pulse energies (but the same focus spot size), measuring the diameters of the features, and using log-linear regression techniques to infer the relevant threshold fluence. this technique is attractive because in addition to the threshold information, it also allows for precise experimental determination of the optical spot size that was used to generate the features.…”

Section: How Pulse Duration Affects Filmremoval Thresholdsmentioning

confidence: 99%

Why Pulse Duration Matters in Photovoltaics

Patel¹,

Bovatsek²,

Tamhankar³

2010

Laser Technik Journal

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In the manufacture of thin‐film photovoltaic (TFPV) solar panels, Q‐switched diode‐pumped solid‐state (DPSS) lasers are routinely used for “laser scribing” – the selective removal of thin‐film materials. These lasers are available at various wavelengths (266–1064nm), output powers (0.5–34W), repetition rates (up to 500KHz) and pulse durations (<10 to greater than 100ns).Developing the ideal laser scribe process – that is, one that removes only the desired material leaving the adjacent material unaffected – can be a challenge. In a non‐ideal scribe process, not only can there be leftover material, but also high ridges can form along the scribe line. Additionally, the supportive glass substrate can develop micro‐cracks that can then cause lift‐off of the thin‐film material. Because these unwanted ridges and burrs interfere with subsequent thin‐film layers, these non‐uniformities can lead to electrical shorts that reduce TFPV efficiencies and yields.This article addresses the various ways in which pulse duration affects the laser scribe process – specifically thin‐film removal thresholds, scribe quality and substrate quality. It is shown that laser systems with shorter pulse durations will generally result in a laser scribe process that has lower material removal thresholds, cleaner scribes and minimal damage to glass substrates, ultimately leading to higher yields and lower overall manufacturing costs of TFPV panels.

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Picosecond laser ablation of thin copper films

Cited by 142 publications

References 12 publications

Atomistic Modeling of Short Pulse Laser Ablation of Metals: Connections between Melting, Spallation, and Phase Explosion

Atomistic Modeling of Short Pulse Laser Ablation of Metals: Connections between Melting, Spallation, and Phase Explosion

Femtosecond Pulsed Laser Deposition of Nanostructured CdS Films

Why Pulse Duration Matters in Photovoltaics

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