Application of focused ion-beam sampling for sidewall-roughness measurement of free-standing sub-μm objects by atomic force microscopy

Abstract

In the present study, a free-standing object-sampling technique for microelectromechanical systems (MEMS) is developed to measure their sidewall surface roughnesses by atomic force microscopy (AFM). For this purpose, a conventional focused ion beam (FIB) sampling technique widely used for cross-sectional transmission electron microscope specimen preparation was applied. The sub-nm-order roughness parameters were quantitatively measured for sidewalls of Si-bridge test samples. The roughness parameters were compared before and after H 2 annealing treatment, which induced smoothing of the surface by migration of the Si atoms. The reduction in the surface roughness by a factor of approximately one-third with 60-s H 2 annealing was quantitatively evaluated by AFM. The present study confirms that the developed FIB–AFM technique is one potential approach for quantitatively evaluating the surface-roughness parameters on the oblique faces of free-standing objects in MEMS devices. FIB sampling technique was developed for AFM measurement of side-wall surface roughness of free-standing objects in MEMS devices. We confi rmed that the proposed FIB-AFM technique is one potential and practical approach to quantitatively evaluate surface roughness of oblique faces of free-standing objects in MEMS devices.