Nano-patterned standards for improving the quantitative capability of laser scanning confocal microscopy for materials characterization

We explore novel means for estimating the sizes of features that lie below the diffraction limits for laser scanning confocal microscopy (LSCM) for non-destructive, quantitative materials characterization. We first employ electron beam lithography to fabricate calibration standards consisting of hollow, nanometer-scale features as small as 70 nm in diameter etched in a poly(methyl methacrylate) photoresist. In addition to a range of feature sizes (D), we have designed these standards to also explore resolution limits through various feature-to-feature spacings. Fluorescence mode LSCM imaging of the features (i.e., saturated with fluorescent dye), and measurements via scanning electron microscopy (SEM) enable us to correlate the fluorescence intensity with the size of the sub-resolution features. Finally, we leverage this calibration for more quantitative interpretation of LSCM images of polycrystalline NaX zeolite membranes.