Experimental test of blind tip reconstruction for scanning probe microscopy

Determination of the tip geometry is a prerequisite to converting the scann ing probe microscope (SPM) from a simple imaging instrument to a tool that can perform width measurements accurately. Recently we developed blind reco nstruction, a method to characterize the SPM tip shape. In principle this m ethod allows estimation of the tip shape from an image of a till characteri zer sample that need not be known independently. In this work, we compare b lind reconstruction results to those obtained by scanning electron microsco py for two diamond stylus profiler tips, one of which has a gentle shape an d the other a more complicated profile. Of the two comparisons, the poorer agreement is still better than 30 nm for parts of the tip within a several micrometer neighborhood of the apex. In both cases the differences are comp arable to the combined standard uncertainties of the measurements. We estim ate uncertainties from five sources, the most significant of which is the r epeatability of the stylus profiling instrument. In a separate measurement we determine the geometry of a silicon nitride SPM tip. The measured radius , 4-fold symmetry, included angle, and tilt are all consistent with expecta tions for such a tip. (C) 2000 Elsevier Science B.V. All rights reserved.