Electron-Induced C─F Bond Activation in Sn₆-oxo Cluster Resist for Enhanced Sensitivity and Sub-10-nm Patterning

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Metal-oxo clusters (MOCs) are promising for extreme ultraviolet lithography (EUVL) but face challenges in optimizing resolution, line-edge roughness (LER), and sensitivity (RLS).
• Dissociative electron attachment (DEA) to C-F bonds offers a potential route to improve RLS trade-offs but is underexplored in MOC resists.

Purpose of the Study:

• To develop a scalable synthesis of tunable tin-oxo clusters for lithographic applications.
• To investigate the lithographic performance and mechanisms of a fluorinated tin-oxo cluster resist (FPAA).
• To establish design principles for MOC resists for sub-10-nm patterning.

Main Methods:

• Room-temperature, scalable synthesis of tin-oxo clusters.
• Electron beam lithography (EBL) and deep ultraviolet (DUV) lithography for patterning.
• Extreme ultraviolet lithography (EUVL) for advanced patterning evaluation.
• Mechanistic studies involving low-energy secondary electrons (LESEs) and dissociative electron attachment (DEA).

Main Results:

• Demonstrated hundred-gram-scale, single-batch production of tunable Sn-oxo clusters.
• Achieved sub-10-nm resolution (9.1 nm CD in EBL) and low LER (2.2 nm) with FPAA.
• Obtained 20.9 nm CD under EUVL and high plasma resistance (>50:1 Si:resist etch selectivity).
• Elucidated DEA-mediated C-F activation and network crosslinking as key lithographic mechanisms.

Conclusions:

• The fluorinated FPAA resist enhances sensitivity and resolution without compromising LER.
• The study provides insights into the lithographic mechanisms of Sn-oxo clusters, particularly DEA activation.
• Design principles for MOC resists are proposed, advancing sub-10-nm lithographic capabilities.