The functional geometry of CD-AFM tips is typically parameterized in terms of several metrics that help to quantify the expected performance and limitations of the tip for specific measurements. For our purposes here, we follow the most common convention, as described by Dahlen et al.29 The three metrics we will emphasize here are: (1) the tip width, which determines the smallest trench that can be measured, (2) the VEH, which limits the bottom portion of the sidewall that can be observed, and (3) the maximum overhang, which determines the limit of undercut or re-entrance of a sidewall that can actually be observed.