Back side photomask haze revisited

Back (glass) side haze on photomasks has been previously reported and continues to present problems in many fabs throughout the industry. While some process changes have resulted in the reduction in both the occurrences and rate at which back side haze forms; proper handling and storage of reticles remains paramount in protecting all surfaces on the reticle from haze formation. We will describe again the basic mechanisms for haze formation and how proper storage can result in significantly reducing the risk of haze formation during storage and use in the fab.