Assessment and Extendibility of Chemically Amplified Resists for Extreme Ultraviolet Lithography: Consideration of Nanolithography beyond 22 nm Half-Pitch

The major resist properties, namely, resolution, line edge roughness (LER), and sensitivity have trade-off relationships. The relationships among them are determined by the pattern formation efficiency. Because of these trade-off relationships, the assessment of resist performance has been a difficult task. The extraction of parameters associated with pattern formation efficiency is important for the proper assessment of resist materials. In this study, we improved the resist model and analysis procedure for the parameter extraction and assessed state-of-the-art extreme ultraviolet (EUV) resists. Using extracted parameters, we evaluated the expected resist performance upon exposure to a next-generation exposure tool with high numerical aperture (NA). Furthermore, assuming the technical limits of resist materials, the extendibility of chemically amplified resists was examined. It was found that the resist requirements (10 mJ cm^-2 sensitivity and 1 nm LER) for the 16 nm node are achievable at NA=0.35, although they were comparable to the assumed technical limit.