KrF excimer laser ablation of thin Cr film on glass substrate

In order to understand the removal mechanism and seek the optimal processin g conditions, KrF excimer laser ablation of Cr films deposited on glass sub strates is investigated. The surface morphology of the laser-irradiated spo t is examined by scanning electron microscopy, and the ablation rate is als o obtained from the energy-dispersive X-ray spectrometry of SEM. The measur ed single-shot ablation rate is found to be about two times the result of n umerical analysis based on a surface vaporization model and heat conduction theory. Surface morphology examination indicates that the Cr film is remov ed by the sequence of cracking-melting-surface vaporization-melt expulsion by plasma recoil, and that the outmost ripple of the diffraction pattern gi ves a strong effect on the morphology of molten Cr during the melting and v aporization processes. Although removal quality is divided into film damage , partial removal, excellent removal, and glass damage, EDXS shows that abo ut 14% of Cr remains even at the excellent removal condition. Optimal fluen ce range which gives excellent removal, good precision of pattern size, and few droplets and cracks, is so narrow that the process conditions for patt erning should be established carefully. From this study, it is found that t hinner films are well ablated by excimer lasers.