A virtual lateral standard for AFM calibration

摘要

Calibration of the lateral scale of scanning probe microscopes using conventional physical calibration standards (i.e. 1D or 2D gratings) has limitations for small scanning ranges imposed by the pitch of the standards. Below approximately 1 pm the number of features on the standards that can be imaged is limited and the effects of imperfections from individual features increase the calibration uncertainty. Additionally, the standards consist of delicate nanostructures that are susceptible to contamination and damage. Due to this delicate nature these standards are less useful in a production environment. We present a lateral calibration method based on a virtual standard that is robust to contamination and damage and also enables the determination of scanner non linearity. In contrast to conventional physical standards the accuracy of the virtual standard does not decrease for smaller scan ranges. The standard is based on a highly linear shear piezo and has no specific requirements for the surface texture that is used during the lateral calibration. The calibration of the shear piezo in the range from 2 pm to 20 nm with a dedicated interferometer and its application as an accurate virtual standard to calibrate the lateral scale and non-linearity of an atomic force microscope will be discussed. (C) 2016 Elsevier B.V. All rights reserved.