Study of EUV Nanostructures Using AFM With High-Aspect Ratio Tip (Purdue, Intel, Bruker)

A new technical paper, “Characterizing tip-sample interaction dynamics on extreme ultraviolet nanostructures using atomic force microscopy with a high-aspect ratio tip,” was released by researchers at Purdue University, Intel Corporation and Bruker Corporation.

Abstract

“Accurate measurements of the nanometer scale geometry of extreme ultraviolet (EUV) lithography photoresist patterns are a critical metrology step in semiconductor manufacturing. The atomic force microscope (AFM) can nondestructively measure 3D surface photoresist (PR) profiles with nanometer resolution. However, geometric and mechanical artifacts limit AFM’s accuracy when measuring tall or narrow features comparable in size to the AFM tip radius. In this work, we investigate tip-sample interaction dynamics on 40 nm pitch EUV PR features using force mapping-based AFM with high-aspect ratio diamond like carbon spike tips. We train and utilize a random forest machine learning algorithm to classify force curves based on their linearity, adhesion, and hysteresis. Some of the observed force curves are consistent with stick-slip friction between the AFM tip and photoresist sidewall during indentation. We compare the AFM measured photoresist profile to those measured with scanning electron microscopy. We conclude that a combination of photoresist shrinkage under electron beam exposure, geometric dilation of the profile due to the finite size of the AFM tip, and bending of the AFM tip as it interacts with the sidewall can explain the experimental results. This study challenges the conventional assumption that high aspect ratio tips with smaller tip radius have capability to reach narrow features; instead, we demonstrate that complex tip-sample interaction dynamics occur around the sidewall. This work contributes to an improved understanding of AFM measurement artifacts associated with high-aspect ratio spike tips on nanometer scale patterns.”

Find the technical paper here.  March 2026. Accepted manuscript.

Jung, Uidam, Todd Hoppe, Jason Osborne, Arvind Raman, and Ryan Wagner. “Characterizing tip-sample interaction dynamics on extreme ultraviolet nanostructures using atomic force microscopy with a high-aspect ratio tip.” Measurement Science and Technology (2026).