Laser Ablation Dynamics of Amorphous Film of a Cu-Phthalocyanine Derivative

Laser ablation dynamics of amorphous film of a Cu-phthalocyanine derivative was studied by using nanosecond interferometry, nanosecond photography, space- and time-resolved absorption spectroscopy, and atomic force microscope (AFM). At 140mJ/cm2, etching of the film was found to begin at the early half of an excimer laser pulse followed by the ejection of gaseous compounds. Since the absorption spectrum of ejected materials was similar to that of the amorphous film, main molecular specie of the ejected materials is the Cu-phthalocyanine derivative, meaning no decomposition even upon laser ablation. It is suggested that photothermal mechanism is responsible for the ablation. It was observed with AFM that surface structure of the PMMA film adhered with ejected materials was covered with humps whose minimum dimension was about 120nm. It is suggested that Cu-phthalocyanine derivative was ejected not as single molecules but as submicron particles upon laser ablation.