Interface engineering of underlayer of chemically-amplified EUV photoresists to enhance the photolithographic performance

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2024-09, Vol.307, p.117539, Article 117539
• Main Authors: Wang, Tao, Zhuang, Changchang, Yang, Guo, Xin, Hanshen, Jiang, Lin, Zhang, Jianhua
• Format: Article
• Language: English
• Subjects: Adhesion; Collapse; Interface; Lithographic performance; Surface energy
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2024.117539

•Systematic study of photoresist-underlayer adhesion for pattern collapse, stochastic failures and line edge roughness.•Hexamethyldisilane is superior to the commercial AR_300-80_new in enhancing the pattern performance.•The polar component plays a key role in photoresist adhesion and line edge roughness.•Optimal lithographic performance desires the balance of wetting, surface energy, and adhesion properties. The high numerical aperture (NA) extreme ultra-violet (EUV) requires a thin layer of photoresist stack, facing great challenges of pattern collapse during photolithography. Underlayers (ULs) emerge as a promising strategy to conquer the challenge via effectively tuning the interfacial adhesion. Two ULs of hexamethyldisilane (HMDS) and a new commercial adhesion promoter (AR_300-80_new) were explored to improve the lithographic performance of a lab-developed EUV chemically amplified photoresist (CAR). The potential impact of wetting properties, surface free energy, and adhesion properties of the ULs on the pattern collapse, stochastic failures and line edge roughness (LER) were systematically examined. HMDS (water contact angle (WCA) = 76.6°, Wsl = 71.8 mJ/m2) is superior to AR_300-80_new (WCA = 44.8°, Wsl = 86.8 mJ/m2) in enhancing the pattern performance. High polarity (18.62 mJ/m2) and low dispersive surface energy (24.75 mJ/m2) components in ULs lead to smaller LER (8.5 nm). The results showed that the polar component of the surface energy plays a determining role in regulating the adhesion of the photoresist to the substrate and its lithographic performance. In addition, a delicate balance between wetting properties, matched surface energy and adhesion properties is required to achieve optimal lithographic performance.