Effect of sub-0.1 μm filtration on 248nm photoresist performance

The implementation of resist filtration below 0.1 μm within existing dispense systems raises concern as the removal rating of the filter approaches the size of large molecular weight components of the photoresist. A comprehensive study has shown, however, that as the filter removal rating became finer, the resist performance in terms of photospeed, process window, and thermal stability did not change. This indicates that, using existing dispense systems, photoresists can be filtered to as fine as 0.03μm without significant polymer shearing or the unintentional removal of important materials from the resist. Based on these data, appropriate protection in terms of particle removal is possible as linewidths necessitate the use of finer filters in resist dispense pumps.