When lasers were introduced three decades ago, initial materials applications were limited due to the narrow range of laser wavelengths that were available. In those early days, infrared and visible lasers (CO2, ruby, and Nd:YAG) were used for welding, cutting, and drilling of different metals.
With the invention of the UV excimer laser in the mid-seventies, a host of new possibilities for material processing emerged. Today, high resolution direct patterning—down to the micron level—is possible for a wide range of materials.
UV lasers offer distinct advantages for direct patterning. Most materials, especially organic polymers, have higher absorption at UV laser wavelengths than at longer wavelengths. The short pulse length, high absorptivity, and high energy density available with UV excimer lasers allow efficient ablation of material. An equally important advantage is the ability to pattern the light beam onto the substrate by projection systems, thereby allowing direct patterning and
obviating the need for the solvents and other wet processing present in conventional photolithography.