DEFECT STUDIES ON SINGLE AND BILAYER RESIST SYSTEMS

Defect detection equipment and procedures to qualify resist systems with regard to defects have been investigated. An analysis was carried out for two bilayer resist systems which were compared to a single layer resist. One of the bilayer resists was developed for the mid-UV exposure range, the other for deep-UV. It showed that the pinhole-limited yield measured by metal-oxide-semiconductor test structures is approximately 10% lower for one of the bilayer resists compared to a single layer resist. The other bilayer resist scheme was compared to a single layer resist with regard to particulates. Here the dry-developed bilayer resist scheme showed approximately four times higher additive defect densities than the wet-developed single layer resist. A short dry etch process for opening an anti reflective coating underneath a single layer resist increased the defect densities. Water rinse steps are capable of reducing these defect levels substantially. The dry-developed resist schemes had higher defect densities, but it is certainly possible to reduce these to the densities of single layer resists.