Reticle Haze Control: Global Update and Technology Roadmap

Three years ago Entegris pioneered a novel method of controlling ammonium sulfate (AS) haze by maintaining 193 nm reticles in a low humidity environment. Since then, this approach has became an industry standard and is widely used in production fabs around the world. Based on analysis of practical applications in HVM fabs, this paper describes a successful approach to reticle haze control, outlines its critical elements and explains its limiting factors. In addition to actual fab data, the paper provides a large body of comparative experimental data on humidity dynamics in different reticle storage schemes and arrangements. With this data, the authors explain why some designs work much better than others and provide practical recommendations for lithography practitioners on haze control equipment selections and reticle management strategy development.