METHODS OF INCREASING THE ACCURACY OF MEASUREMENT WITH A SCANNING PROBE MICROSCOPE DEPENDING ON THE GEOMETRY OF THE PROBE

Abstract

The article analyzes the influence of different types of probe geometry of a scanning probe microscope (SPM) on the features of measuring the surface topography of a nano-object. Based on the analysis, it was determined that the main drawback inherent in all modes of scanning probe microscopy is the finite size of the measuring probe tip, which cannot reach certain areas of the measuring surface during scanning, which is caused by the geometric characteristics of the probe shape. This leads to a significant deterioration of the spatial resolution and significant distortions in the SPM images when scanning surfaces with large unevenness of the ratio between the typical vertical and horizontal dimensions. Based on the conducted research, the methods of restoration of SPM images are proposed, which are built on mathematical and computer processing of SPM data, which takes into account the specific shape of the probe tip and allows improving the metrological characteristics of the measurement information. It is proved that the SPM image and the experimentally obtained shape of the tip are two-dimensional arrays of discrete values, for which the derivative is an incorrectly determined value. It is recommended that instead of deriving discrete functions during the numerical deconvolution of SPM images, during scanning with a constant average height, use the requirement for the minimum distance of the tip to the surface. It has been proven that the most effective way of digital correction of the surface topography is numerical deconvolution using the tip image obtained experimentally by scanning test structures with a well-known topography and subsequent computer processing of the data. A method of partial restoration of the topography is proposed, which is characterized by flexibility to the set metrological tasks and is aimed at increasing the speed of computing operations while ensuring the necessary accuracy of measurement information.