24'x 20' precision photomasks manufacture

摘要

Abstract: Large area masks (LAMs) and 1X lithography are being used in the manufacturing of large area electronic devices. Some of these devices include, but are not limited to: flat panel displays (FPDs), active matrix liquid crystal displays (AMLCDs), electroluminescent flat panel displays (ELFPD), plasma display panels (PDPs), multichip modules (MCMs), and advanced interconnect systems. The use of LAMs along with 1X lithography reduces the cost of manufacturing these types of devices. However, there are several challenges in the manufacturing of LAMs. The first challenge is the lack of large area, quality substrates with quality coatings. The different types of substrates and the coatings presently available for large area photomasks are reviewed. The second challenge comes in dealing with the limitations of commercially available exposure systems used in writing LAMs. In this paper, we present an overview of several exposure systems, now available, and their resolution capabilities. The third challenge is the lack of availability of systems for the processing of photomasks larger than 14' by 14'. Processing systems for manual and automatic plate loading are also discussed. The final challenge to manufacture LAMs is inspection and quality certification. Presently, there is a void of commercially available metrology tools that can be used to measure and quantify defects on LAMs. Metrology techniques available for certifying finished LAMs are discussed along with their quality assurance capabilities. Current LAMs availability and specifications are also presented including LAMs with active areas as large as 20' by 18' (508 by 450 mm) and CDs of 2.0 micrometer. !8