Chemically Resolved IR-AFM Metrology of Sub-25 nm Half-Pitch Patterns in Self-Assembled Block Co-Polymers

Resist stochastics ultimately limit patterning, a result of interplay of resist composition, exposure, bake and development. Metrologies like OCD and CD-SEM only measure uniformity after development, offering limited process control. Each step modifies molecular bonds, leaving IR (5-20 μm) fingerprints in activated chemical structures. When combining IR & AFM, nearfield effects resolve alterations at the nm scale. We show how IR-AFM offers chemical selectivity and lateral resolution to resolve modifications in latent DSA and EUVL images, even before PEB and development. Metrology data from these images facilitate improved process control.