The Impact of Polymer Compositional Homogeneity on Lithography and Defects

Herein the after-develop inspection (ADI) and after-etch inspection (AEI) for pitch 36 nm & pitch 28 nm trench features for two EUV chemically amplified photoresists (CAR) using different polymers are compared. In this study MALDI was used to compare the compositional homogeneity of co-monomers through molecular weight of the two polymers. The measured differences in compositional homogeneity impacted lithography and defectivity. More homogeneous monomer distributions through molecular weight resulted in lower LWR at both pitches. Interestingly, lower AEI defectivity was found for the less homogeneous polymer. A model to explain this counterintuitive trend was developed based on known impacts of changing monomer composition on the material properties. The insights gained from this study demonstrate the importance of controlling compositional homogeneity and the benefits that optimizing polymer homogeneity can have on LWR and AEI defectivity.