Direct observation of phase transitions by time-resolved pyro/reflectometry of KrF laser-irradiated metal oxides and metals

Semmar, Nadjib; Tebib, M.; Tesař, Jiří; Puscas, Niculae N.; Amin-Chalhoub, Eliane

doi:10.1016/j.apsusc.2008.08.084

Cited by 12 publications

(8 citation statements)

References 16 publications

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“…concluded that liquid phase can last up to 300 ms for Ti under the laser fluence of 1 J/cm 2 [30]. Hence for Ti alloy ablated at 5 kHz, the laser pulses will irradiate on a melt surface.…”

Section: Discussionmentioning

confidence: 98%

“…3). Since many experiments have found that plasma formation occurs on a timescale between picosecond and tens of microseconds [28][29][30], one can expect that there should be no interaction between a current laser pulse and its following plasma when the laser repetition rate <5 kHz. It means any plasma will be certainly gone when the next laser pulse arrives.…”

Section: Discussionmentioning

confidence: 98%

See 1 more Smart Citation

Effects of laser operating parameters on metals micromachining with ultrafast lasers

Cheng

Perrie

Edwardson

et al. 2009

Applied Surface Science

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“…concluded that liquid phase can last up to 300 ms for Ti under the laser fluence of 1 J/cm 2 [30]. Hence for Ti alloy ablated at 5 kHz, the laser pulses will irradiate on a melt surface.…”

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 98%

Effects of laser operating parameters on metals micromachining with ultrafast lasers

Cheng

Perrie

Edwardson

et al. 2009

Applied Surface Science

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“…These situations explain the removal of copper from the surface that increases as increasing the number of laser shots (from 1 to 150). The shift of the TRR signal (≈4 mV and 9 mV [15]. In opposite, in the case of sample 4, the melting kinetics is the most dominant mechanisms and the typical TRR signals evolve to their initial values after a negative drop.…”

Section: Effect Of Number Of Laser Shot and Substratementioning

confidence: 89%

“…Laser heating and melting of semiconductors (especially silicon) have been done by nanosecond pulsed laser [4][5][6]. Melting duration, threshold for metallic thin films upon pulsed laser annealing were determined by time-resolved reflectivity method [7,[13][14][15]. On time scale of microseconds, the longest melting duration in the interaction of the excimer laser with gold films about a few microseconds [2] and amorphous Si thin films about 1.7 μs [8] was determined by the reflectance measurements of Ar + ion and He-Ne probe lasers respectively.…”

Section: Introductionmentioning

confidence: 99%

In-situ and ex-situ ripples formation on copper thin films induced by nano and picosecond pulsed lasers

Huynh

Petit

Pichard

et al. 2012

AIP Conference Proceedings

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Laser induced periodic surface structure (LIPSS) process on copper thin films by nano and picosecond pulsed lasers was analyzed by scanning electron microscope (SEM) and time resolved reflectivity (TRR) methods. The 500nm and 1000nm thickness of copper thin films were deposited on silicon and glass substrates by magnetron sputtering technique. Different periodic surface micro and nanostructures of copper thin films (thickness of 1000nm) on silicon substrate were observed post-mortem by SEM. Namely, a wrinkling microstructure and classical ripple with period spatial near wavelength of laser (approximately 266nm) were induced by nanosecond pulse laser at fluence 100 mJ/cm 2 . The conical nanostructure and ripple microstructure were induced by picosecond pulse laser. TRR method permits the real time monitoring of melting and/or surface morphology changes. The reflectivity signals have shown the increase of the removal copper thin film as increasing the laser fluence and of the number of laser shots. Under the same laser conditions (fluence and number of shots), copper thin films on glass were removed easier than on silicon case due to the intrinsic thermal conductivity of substrate. An obtained TRR signal of wrinkling formation was induced by nanosecond pulse laser. TRR method is suitable for monitoring LIPPS in the nanosecond but not in the picosecond. However, SEM analyses give more information and details of the structure changes in the nano and picosecond. We can assume that mainly thermal 'drift' forces are responsible for wrinkling microstructure formation in the nanosecond regime, and photonic forces for periodic surface nanostructure formation in the picoseconds one.

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“…Consequently, the melt layer persists for a longer time, approximately 300 µs [36]. If we consider the repetition rate, at 1 kHz the pulses are 999 µs apart.…”

Section: Discussionmentioning

confidence: 99%

Effect of Repetition Rate on Femtosecond Laser-Induced Homogenous Microstructures

2016

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We report on the effect of repetition rate on the formation and surface texture of the laser induced homogenous microstructures. Different microstructures were micromachined on copper (Cu) and titanium (Ti) using femtosecond pulses at 1 and 10 kHz. We studied the effect of the repetition rate on structure formation by comparing the threshold accumulated pulse (Fsans-serifΣpulse) values and the effect on the surface texture through lacunarity analysis. Machining both metals at low Fsans-serifΣpulse resulted in microstructures with higher lacunarity at 10 kHz compared to 1 kHz. On increasing Fsans-serifΣpulse, the microstructures showed higher lacunarity at 1 kHz. The effect of the repetition rate on the threshold Fsans-serifΣpulse values were, however, considerably different on the two metals. With an increase in repetition rate, we observed a decrease in the threshold Fsans-serifΣpulse on Cu, while on Ti we observed an increase. These differences were successfully allied to the respective material characteristics and the resulting melt dynamics. While machining Ti at 10 kHz, the melt layer induced by one laser pulse persists until the next pulse arrives, acting as a dielectric for the subsequent pulse, thereby increasing Fsans-serifΣpulse. However, on Cu, the melt layer quickly resolidifies and no such dielectric like phase is observed. Our study contributes to the current knowledge on the effect of the repetition rate as an irradiation parameter.

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Direct observation of phase transitions by time-resolved pyro/reflectometry of KrF laser-irradiated metal oxides and metals

Cited by 12 publications

References 16 publications

Effects of laser operating parameters on metals micromachining with ultrafast lasers

Effects of laser operating parameters on metals micromachining with ultrafast lasers

In-situ and ex-situ ripples formation on copper thin films induced by nano and picosecond pulsed lasers

Effect of Repetition Rate on Femtosecond Laser-Induced Homogenous Microstructures

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