エキシマ・レーザー・アブレーションによる生成金属粒子および金属膜の観察

抄録

Metal particles generated by excimer laser ablation are observed. Effects of laser conditions and target materials on particles are also studied. The ArF and KrF excimer laser beam are irradiated on Cu, Ni and Al plate targets in the vacuum. Laser plume is generated from the irradiated surface of a target. Then, thin film is deposited on a substrate. Surfaces of thin films and targets are observed by scanning electron microscope. Spectroscopic observation and mass-spectroscopic study of the plume are also carried out. The main results obtained are as follows.
(1) Thin films deposited on the substrates contain particles with diameters of 1∼10 μm. The diameter and number of particles in Al films are greater than those in Cu or Ni films. They also get smaller for lower laser fluence.
(2) Thicknesses of thin films linearly increases with laser fluences. Thicknesses obtained under KrF beams are greater than those under ArF beams.
(3) Surfaces morphologies of targets after laser irradiation differs with target materials. Corn morphology is obtained with Cu, the flat one with Ni and the lump one with Al, respectively.
(4) Laser plume contains a neutral atom and charged ions (M⁺ and M²⁺). Under ArF beams, M²⁺ ions are more easily generated than under KrF beams. Higher excited state is obtained in the case of higher irradiation angle. And higher intensity of optical emission is observed under higher laser fluence or higher frequency of irradiation.