After quartz blanks with various sulfate ion amount on the surfaces were exposed by an ArF laser, growing defects, haze,
on the surfaces were consequently counted by an inspection tool. As a result, the number of haze largely depends on the
sulfate ion amount, and it is found that no haze is generated when the sulfate ion amount is smaller than a threshold value.
A new haze generation model is provided to explain the threshold phenomenon. And then storage impact on increase of
the sulfate ion amount was investigated. The sulfate ion amount increases with storage time and airborne SOx
concentration. From the results, the adsorption coefficient of an extended Langmuir equation was calculated, and the
adsorption phenomenon was analyzed in detail. Simulation results show that it is recommended, regarding for storage
environment, to keep under 0.01 ppbv airborne SOx concentration in order to prevent haze for one year.
|