Deconvolution processing for increasing the resolution of magnetic force microscopymeasurements

Abstract

Magnetic force microscopy (MFM) is a widely used form of scanning probe microscopy(SPM) that is used for obtaining a magnetic image from a surface with nanoscaleresolution. Currently, the resolution of MFM is limited to approximately 20 nm due to thelong-range nature of magnetic interactions between the MFM probe’s tip and themagnetic medium. This paper describes an optimal signal processing solutionto the problem of achieving high resolution MFM with the goal of significantlyexceeding the level at which MFM metrology currently performs, thus providingmetrologists with a means of resolution increase that is believed will enable, forexample, the rapid development of high-density magnetic recording media(>100 Gbit in−2). This is achieved by using focused-ion beam trimming of a conventional tip to create aprobe tip of predictable magnetic characteristics and then, provided that the sample couldbe approximated as a thin-film, using knowledge of this tip’s sensitivity field for performinga deconvolution on the measured signal to better estimate the magnetic state of the surfaceunder study. Stated differently, as the MFM measured signal is modelled as the convolutionof the magnetized surface and the tip’s sensitivity field, we exploit knowledge of the tip’sproperties to increase the resolution of the MFM image. Details of the deconvolutionapproach as well as images resulting from this processing are the focus of this paper.