Emission spectra and etching of polymers and graphite irradiated by excimer lasers

Koren, G.; Yeh, J. T. C.

doi:10.1063/1.334211

Cited by 147 publications

(22 citation statements)

References 10 publications

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“…At an energy density below 0.5 J/cm2, only the broad continuum spectrum was observed. These spectra are the same as those already reported by Koren and Yeh [7,8]. Almost the same emission spectra in air, argon, and helium were also observed with a XeCI excimer laser.…”

Section: Resultssupporting

confidence: 78%

Polymer processing with excimer lasers.

Ishizaka¹

1993

J. Photopol. Sci. Technol.

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Section: Resultssupporting

confidence: 78%

Polymer processing with excimer lasers.

Ishizaka¹

1993

J. Photopol. Sci. Technol.

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“…Infrared spectroscopy [69], gas chromatography [166], and mass spectrometry [272] have been used to identify the principal gaseous products of Kapton ablation: CO 2 , CO, H 2 O, HCN, and various light hydrocarbons (up to four carbon atoms). Laser-induced fluorescence measurements indicate that diatomic fragments C 2 and CN are also formed, at least transiently, during ablation [273]. Larger molecules (e.g., C 60 ) up to visible carbon particles are also formed [274].…”

Section: Laser Application Of Polymersmentioning

confidence: 99%

Laser Application of Polymers

Lippert

2004

Polymers and Light

150

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Laser ablation of polymers has been studied with designed materials to evaluate the mechanism of ablation and the role of photochemically active groups on the ablation process, and to test possible applications of laser ablation and designed polymers. The incorporation of photochemically active groups lowers the threshold of ablation and allows high-quality structuring without contamination and modification of the remaining surface. The decomposition of the active chromophore takes place during the excitation pulse of the laser and gaseous products are ejected with supersonic velocity. Time-of-flight mass spectrometry reveals that a metastable species is among the products, suggesting that excited electronic states are involved in the ablation process. Experiments with a reference material, i.e., polyimide, for which a photothermal ablation mechanism has been suggested, exhibited pronounced differences. These results strongly suggest that, in case of designed polymers which contain photochemically active groups, a photochemical part in the ablation mechanism cannot be neglected. Various potential applications for laser ablation and the special photopolymers were evaluated and it became clear that the potential of laser ablation and specially designed material is in the field of microstructuring. Laser ablation can be used to fabricate three-dimensional elements, e.g., microoptical elements.Keywords Laser ablation · Ablation mechanism · Photopolymers · Polyimide · Spectroscopy This was not always true, of course. For many years, the laser was viewed as "an answer in search of a question". That is, it was seen as an elegant device, but one with no real useful application outside of fundamental scientific research. In the last two to three decades however, numerous laser applications have moved from the laboratory to the industrial workplace or the commercial market. Lasers are unique energy sources characterized by their spectral purity, spatial and temporal coherence, and high average peak intensity. Each of these characteristics has led to applications that take advantage of these qualities: -Spatial coherence: e.g., remote sensing, range finding and many holographic techniques. -Spectral purity: e.g., atmospheric monitoring based on high-resolution spectroscopies. -and of course the many other applications in communication and storage, e.g., CDs.All of these high-tech applications have come to define everyday life in the late twentieth century. One property of lasers, however, that of high intensity, did not immediately lead to "delicate" applications but rather to those requiring "brute force". That is, the laser was used in applications for removing material or heating. The first realistic applications involved cutting, drilling, and welding, and the laser was little more advanced than a saw, a drill, or a torch. In a humorous vein A.L. Schawlow proposed and demonstrated the first "laser eraser" in 1965 [4], using the different absorptivities of paper and ink to remove the ink without damaging the und...

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“…The new tail might be a plasma-like emission and suggests that a new ablation process is involved. This type of emission has been confirmed also for polyimides, PMMA, graphite, and biological tissues (2,21,22). The Bremsstrahlung and recombination processes may respond to the continuum in problem.…”

Section: Laser Ablation Dynamics Of Pvcz Filmmentioning

confidence: 65%

“…While a plasma-like emission and fluorescence behavior of ablated radicals have been reported (21,22), fluorescence dynamics of the polymer itself has been considered for the first time in the present work. A typical temporal characteristic of PVCz film at 1.3 J/cm 2 fluence was as follows.…”

Section: Resultsmentioning

confidence: 96%

Molecular Studies on Laser Ablation Processes of Polymeric Materials by Time-Resolved Luminescence Spectroscopy

Masuhara¹,

Itaya

Fukumura

1989

ACS Symposium Series

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By fluorescence analyses just upon laser ablation and of ablated surface, molecular aspects of ablation mechanism were elucidated and a characterization of ablated materials was performed. Laser fluence dependence of poly(N-vinylcarbazole) fluorescence indicates the inportance of mutual interactions between excited singlet states. As the fluence was increased, a plasma-like emission was also observed, and then fluorescence due to diatomic radicals was superimposed. While the polymer fluorescence disappeared mostly during the pulse width, the radicals attained the maxi mum intensity at 100 ns after irradiation. Fluorescence spectra and their rise as well as decay curves of ablated surface and its nearby area were affected to a great extent by ablation. This phenomenon was clarified by probing fluorescence under a microscope.There are a number of reports concerning laser ablation of polymeric materials in relation to microelectronics technology (1-8).Most of the polymers studied were polyimide, poly(methyl methacrylate), poly(ethylene terephthalate) and some photoresists. They have carbonyl as well as amino groups and hetero-atoms. In view of photophysics and photochemistry, this means that fluorescence lifetime is very short, intersystem crossing occurs with high quantum yield, and they are photochemically reactive (9).On the other hand, there are other series of polymers having π-electronic chromophore such as N-carbazolyl and 1-pyrenyl groups, whose photophysical properties are quite different from the above polymers and whose laser chemistry is studied in detail. A relation among interchromophoric interaction, spectral shape and geometrical structure in the excited singlet, triplet, cationic and anionic 1 Current address: ERATO, JRDC (1988-1993), 15 Morimoto-cho, Shimogamo, Sakyo-ku,

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Emission spectra and etching of polymers and graphite irradiated by excimer lasers

Cited by 147 publications

References 10 publications

Polymer processing with excimer lasers.

Polymer processing with excimer lasers.

Laser Application of Polymers

Molecular Studies on Laser Ablation Processes of Polymeric Materials by Time-Resolved Luminescence Spectroscopy

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