Improved excimer laser pattern generator for photomask fabrication

Abstract

This paper describes a laser pattern generator constructed by modifying a GCA 3600F tool for the production of research photomasks. The mercury arc lamp illumination source was replaced with an excimer laser. Extensive modifications made to the subsystems and software are described. The result is a tool with a 25× average throughput improvement, a resolution of 1.0 μm, and an 8× increase in overlay precision. The laser pattern generator retains the ease of operation of the original system and exhibits improved reliability. The overall cost of the implemented improvements is a small percentage of a state-of-the-art laser or electron beam mask generation tool. We report on the results of generating 2×, 5× and 10× reticles as well as 1× photomasks from the past three years.