Publication
Applied Physics Letters
Paper

Emission spectra, surface quality, and mechanism of excimer laser etching of polyimide films

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Abstract

Emission spectra in the visible and ultraviolet range, and scanning electron microscopy of polyimide films exposed to 193, 248, and 351-nm laser radiation were used to elucidate the mechanism of the laser etching process. It was found that rough laser etched surfaces, with nonuniformities larger than 0.5 μm, are accompanied by a continuum emission from the blow-off materials, while smooth surfaces are characterized by strong C2 emission in the A 3Πg→X′ 3Πμ bands. Smoothly etched surfaces were obtained for all laser wavelengths provided the energy absorbed per unit volume in the surface exceeds a threshold value of (5.0±0.5)×104 J/cm3. It is suggested that surface smoothness results from transient melting and that the laser etching mechanism is mostly a statistical thermodynamic process without complete energy randomization.

Date

01 Dec 1984

Publication

Applied Physics Letters

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