The Use of Scanning Conduction Microscopy to Probe Abrasion of Insulating Films
Hipps, K. W.
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The scanning force microscope (SFM) is a useful tool for examining the consequences of tribological wear, particularly on inherently flat surfaces such as single crystals. How- ever, on moderately rough surfaces, changes in topography due to tribological loading are often difficult to interpret in terms of wear processes. We have examined the wear of an important class of coatings, namely fluorocarbon thin films deposited on stainless steel, using a simple modification of standard SFM techniques. Metal-coated silicon nitride tips are used to probe current flow between the tip and the con- ducting substrates. Simultaneous topography and conduction images are acquired. During wear (performed outside of the SFM), localized thinning of the film and exposure of bare metal are easily and unambiguously detected by this method on size scales less than 50 nm. We describe the technique and present results on two types of fluorocarbon thin films. This technique is similar in spirit to the use of combined STM/SFM imaging, ’ and spatially resolved potentiometry used recently to image potentials of metallic structures on integrated circuits2 Point-by-point measurements of semi- conductor conductivity have also been made using an SFM with conducting tips in efforts to probe semiconductor doping profiles as well as spatially controlled potentiometry for thin-film structures."