High Force Sensitivity Composite Nanofluidic AFM Cantilever

The objective of this paper is to design and fabricate a low stiffness cantilever with an enclosed nanofluidic channel. This paper addresses the primary challenge of current hollow cantilever design, and introduces the use of a thermally decomposable polymer as the enabling technology to form a reduced stiffness, and thus higher sensitivity, cantilever. A numerical stiffness model is first developed to identify the critical geometric parameters necessary for structural soundness and bendability. A new sacrificial material is then introduced to cantilever fabrication that uses a low temperature top coat layer of plasma enhanced chemical vapor deposition nitride. Experimental measurement of the film's internal stress and the resulting bending radius of a composite cantilever are used to characterize residual stress from film deposition as a new design parameter, unique to this method, which was mitigated by a thorough analysis of the combined effect of film properties and cantilever mechanics. A numerical model is developed for optimizing cantilever geometry and refining film process parameters to minimize the internal stress of the cantilever, whilst achieving a low stiffness, high sensitivity, and composite nanofluidic atomic force microscopy cantilever.