With the use of 193nm lithography, haze growth has increasingly become a critical issue for
photomask suppliers and wafer fabs. Recent photomask industry surveys indicate the occurrence
rate of haze is 10 times higher on 193nm masks compared to 248nm masks. Additionally, work has
been presented that shows strong relationship between environmental conditions around the
photomask and the occurrence of haze at 193nm. This underscores the need to better understand
the basic mechanisms of haze and the measures such as environmental airborne molecular
contamination (AMC) control which can be employed to reduce the occurrence of haze in use.
A custom excimer laser test system capable of 193nm and 248nm wavelengths was built to
accelerate haze growth and to better understand haze formation mechanisms. Work on materials
impact on haze growth, such as pellicles and reticle compacts, as well as preliminary findings on
environmental impacts have been presented previously. Results indicate even on pristine
surfaces haze can grow when contaminants are present in the storage and use environment. The test
system has been upgraded to include tight control on the concentration of specific airborne
contaminants of concern. The impact of these contaminants and their relative concentrations will be
examined in this paper and are presented to aid the industry in determining the level of
environmental control needed over the life of a reticle.