Laser Wavelength Dependence on Photochemical Surface and Interface Modifications of Aluminum Thin Films on Silica Glass

摘要

Photochemical surface and interface modifications of Al thin films on silica glass were successfully carried out using a 157nm F_2 laser for micropatterning. The surface modification phenomenon was discussed in relation to by changing the laser wavelength using a 193 nm ArF laser or a 266 nm neodymium-doped yttrium aluminum garnet (Nd:YAG) laser. The ArF laser could induce the surface modification of Al thin films to form a protective AI_2O_3 layer resistant to KOH aqueous solution, similarly to the F_2 laser. However, the mechanical hardness of the ArF-laser-irradiated sample was clearly lower than that of the F_2-laser-irradiated sample. The origin of the surface modification was examined by irradiating the F_2 laser in vacuum. The interface modification phenomenon was analyzed by X-ray photoelectron spectroscopy in the three cases. The adhesion strengths of the samples were also compared. The 266 nm Nd:YAG laser was not effective for the present photochemical modifications.