Artifacts in SPM measurements of thin films and coatings

Abstract

Ideally, scanning probe microscopy (SPM) should generate a three-dimensional map of a sample surface such that the result is an exact replication of the actual sample. Any measurement data that result in an image differing from the actual sample surface are artifacts. The chief sources of SPM artifacts are mechanical systems, piezoelectric crystals, electronic scanners, tip-sample interaction, and image processing. For example, choosing the proper SPM probe for a specific sample is only the first step in minimizing probe-related artifacts. In fact, geometrical effects cause the largest number of artifacts. Good quality atomic SPM images can be clearly seen in raw data and should respond appropriately when the scan range or rotation is changed. Because SPM images are often periodic, it is possible for heavily filtered “data” to sometimes be misinterpreted as “atomic resolution images”. This paper presents SPM image studies using a range of materials from hard rough diamond films to soft nanometer smooth polyimide films. The investigation brings out the hidden sources of SPM artifacts for samples with different geometries and physical properties. Ten suggestions are presented which, if implemented/followed, should minimize the number of SPM image artifacts thereby assuring high quality images.