Pellicle dimensions for high NA photomasks

摘要

At photomask manufacturing, post pellicle inspection suffers from an interference of pellicle size and height dimensions with the inspection equipment requirements. This pellicle shadow causes non-reliable inspection results. The evolution of this effect as well as similar potentially upcoming effects during other lithography processes need to be understood in order to identify potential problems ahead of time and guide the industry accordingly. The study recommends standardizing pellicle size and height dimensions in order to coordinate the required changes at scanner, mask inspection, mask metrology and pellicle vendors in the near and long term. Since frequent changes in other pellicle properties are expected over time to fulfill the requirements for high NA lithography and haze reduction, a standard in pellicle dimensions will also help controlling the complexity of pellicle variations.