Low-cost mask for excimer laser projection ablation

Abstract

Excimer laser projection ablation is a dry 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 extensively in the microelectronics industry for patterning both organic and inorganic materials. Excimer laser projection ablation requires the use of a mask which is similar to a conventional 1X photomask. The laser ablation mask must withstand significantly higher energy densities than conventional photolithographic masks. A dielectric mask structure which consists of a quartz substrate coated with a stack of dielectric thin films has been developed for this process. Although the dielectric mask has been used successfully in a manufacturing environment, it suffers from the disadvantages of a complex fabrication process and high cost. Alternatives to the dielectric mask have been explored and a new mask has been developed which consists of an aluminum film on a quartz substrate. This mask meets the requirements for the laser ablation process and has the advantage of a low cost fabrication process which is similar to conventional chrome on quartz photomasks. The mask development, specifications, fabrication and results are discussed. ©2005 Copyright SPIE - The International Society for Optical Engineering.