Mask technology for excimer laser projection ablation

Abstract

Excimer laser projection ablation is a dry, precise patterning process in which an intense beam of ultraviolet light from an excimer laser is used to directly pattern a material. This technique has been used in industrial applications for patterning both organic and inorganic materials. In the manufacturing of microelectronic devices, laser ablation is used extensively to pattern insulating layers in the multi-level thin film packages. Excimer laser projection ablation is very similar to optical projection lithography, both using a photo mask or reticle which contains a master pattern. The mask used in a IX projection laser ablation tool, however, must withstand significantly higher energy densities than conventional photolithographic masks. A number of mask technologies have been developed specifically for IX excimer laser projection ablation. These masks include dielectric layers on quartz masks, thick films of aluminum on quartz masks, binary phase shifted grating masks and holographic masks. This paper will present a review of these mask types. Critical issues such as fabrication processes, advantages and disadvantages, cost and availability of each mask will be discussed.