Laser Ablation Dynamics of Amorphous Film of a Cu-Phthalocyanine Derivative Masahiro HOSODA*,**, Hiroshi FURUTANI*,**. Hiroshi FUKUMURA*,** Hiroshi MASUHARA*, Masanobu NISHII*** Nobuyuki ICHINOSE**,***, and Shunichi KAWANISHI**,*** *Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita Osaka 565 **Advanced Science Research Center, Japan Atomic Energy Research Institute, 25-1 Mii-minami, Neyagawa Osaka 572 **Kansai Research Establishment, Japan Atomic Energy Research Institute, 25-1 Mii-minami, Neyagawa Osaka 572 (Received March 3, 1997) 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. Key Words: Laser ablation, Amorphous film, Cu-phthalocyanine, Nanosecond interferometry, Nanosecond photography, AFM

Fig.1 Chemical structure of a Cu-phthalocyanine derivative (Savinyl Blue GLS). Fig.3 Etch depth of amorphous film of a Cu-phthalocyanine derivative as a function of 351nm excitation fluence. Fig.2 Absorption spectrum of amorphous film of a Cu-phthalocyanine derivative. Fig.4 Nanosecond time-resolved interference images of amorphous film of a Cu-phthalocyanine derivative at the fluence of 140mJ/cm2.

Fig.5 Etching dynamics of amorphous film of a Cu-phthalocyanine derivative at the fluence of 140mJ/cm2. No information was available between -13 and +9ns (hatched time region). Broken line is the final etch depth and thin solid line is a time profile of the excimer laser pulse. Fig.6 Nanosecond photographs of amorphous film of a Cuphthalocyanine derivative at the fluence of 140 mj/cm2. Fig.7 Positions which was measured by space- and timeresolved absorption spectroscopy.

Fig.8 Comparison between the absorption spectrum of amorphous film of a Cu-phthalocyanine derivative (dashed lines) and that of ejected materials (solid line) at the fluence of 70mJ/cm2 (t = 100ƒÊs). Fig.10 Absorption spectra of ejected materials as a function of the position from the surface of amorphous film of a Cu-phthalocyanine derivative. Fig.9 Normalized absorption spectra of amorphous film of a Cu-phthalocyanine derivative (dashed lines), ejected materials (solid line) at the fluence of 140 mj/cm2 (t = 100t.ts, 2mm), and Cu-phthalocyanine vapor. Fig.11 AFM images of (a) the surface of a PMMA film and (b) the surface of ejected materials on PMMA film.

1) M. Spath and M. Stuke: Appl. Surf. Sci. 54 (1992) 237. 3) H. Furutani, H. Fukumura, and H. Masuhara: Appl. Phys. Lett. 65 (1994) 3413. 5) Y. Tsuboi, H. Fukumura, and H. Masuhara: Appl. Phys. Lett. 64 (1994) 2745. 6) H. Fukumura, E. Takahashi, and H. Masuhara: J. Phys. Chem. 99 (1995) 750. 7) A. S. Davydov: Theory of Molecular Excitons (Plenum, NewYork, 1971). 8) M. Ichikawa, H. Fukumura, H. Masuhara, A. Koide, and H. Hvakutake: Chem. Phys. Lett. 232 (1995) 346. 17) H. Fukumura, N. Mibuka, S. Eura, H. Masuhara, and N. Nishi: J. Phys. Chem. 97 (1993) 13761. 18) H. Fukumura and H. Masuhara: Chem. Phys. Lett. 221 (1994) 373.