Surface engineering using excimer lasers

Excimer laser irradiation of insulators produces structural and chemical modifications in the near-surface region of these materials. These changes have lead to the usage of excimer lasers to engineer the surface of insulators for various applications, as illustrated in four examples presented here: i) Laser-enhanced bonding of deposited metallic films. A very strong bonding between metallic films and Al2O3 can be achieved if the substrates are pulsed-laser treated prior to deposition. AES reveals that strong bonding occurs when an intermediate interfacial compound forms as a metallic film is deposited on a laser-irradiated substrate. ii) Laser encapsulation of metallic particles in silica. Thin films of gold copper and iron deposited on silica can become encapsulated as small particles upon pulsed laser irradiation. XTEM indicates two distinctive stages in the encapsulation process, during one laser pulse. In the first stage, the film melts and dusters into small particles, and in the second stage, the particles are driven into the substrate. iii) Laser-induced surface activation for electroless deposition. In this process, a pattern is imprinted on a substrate by laser irradiating its surface through a mask. Upon immersion of the substrate in an electroless solution, a metallic film is deposited only on the laser-exposed area. Auger emission spectroscopy (AES) and cross sectional transmission electron microscopy (XTEM) indicate that electroless deposition is promoted by the presence of metallic aluminum in AlN and in Al2O3, and of substoichiometric oxide in Al2O3, as well. Other laser irradiation effects that also could induce activation are analyzed. iv) Laser-induced deactivation of a previously activated area.