Excimer laser processing of BK7 and BGG31 glasses

Abstract

Large-area excimer laser processing of BK7 and BGG31 glasses was investigated for laser etching and laser-assisted metallization. Laser etching experiments were performed at wavelengths of 193, 248 and 308 nm and energy densities up to 5 J/cm^2 in various inert and reactive gases. The investigations revealed a good applicability of ArF excimer lasers for nondestructive laser etching of glass. The laser etching behavior is characterized by a characteristic threshold energy density of the order of 1 J/cm^2. Below this threshold laser etching is achieved only in reactive gases and is typically of the order of 0.1 nm/pulse. Above this specific threshold energy density the etch rate rapidly increases and is practically independent of the gas nature but depends more strongly on the gas pressure. In this ablation region the etch rate is of the order of 0.1 µm/pulse. A qualitative thermal model describing laser etching of glass in the ablation region is discussed. Laser-assisted metallization of glass surfaces has been achieved upon excimer laser irradiation of thin organometallic films on the glass surface and post-processing by electroless plating. Metallic nickel deposits showed a good adhesion and structures of a size between several 10 µm and a few millimeters were produced