User-oriented evaluation of the metrological characteristics of areal surface topography measuring instruments

Areal surface topography measurement is becoming more and more widespread. In this context, increased activities in the field of standardization can be observed in order to ensure comparable measurement results. A current hot topic in the field of standardization is areal calibration, which is going to be defined in the upcoming standard ISO 25178-700. Besides, the metrological characteristics of the ISO 25178-600, representing the properties to be calibrated, as well as the corresponding material measures of the ISO 25178-70, used for imaging, are required for a comprehensive standardization of areal calibration. It can be expected that the application of the calibration guidelines is challenging as no easy-to-implement guidelines for the evaluation routines will be included. In this paper, the standards required for areal calibration are briefly presented and their metrological properties are described. A user-friendly implementation of the algorithms required for the evaluation will be discussed in detail. The basic metrological characteristics to be evaluated are the flatness deviation, measurement noise, the topography fidelity, the amplification coefficients and linearity deviations of all axes, the x/y mapping deviation and the topographic spatial resolution. With Two-Photon laser lithography, all required material measures to calibrate a measurement device according to ISO 25178 can be printed on one single calibration artefact. Based on this universal artefact, user-oriented evaluation routines to determine the aforementioned metrological characteristics are introduced and a software package implementing the algorithms and supporting the user effectively during the holistic calibration of areal surface topography measuring instruments is described.