A heater-integrated scanning probe microscopy probe array with different tip radii for study of micro-nanosize effects on silicon-tip/polymer-film friction

Electric-heated cantilever-tip probes fabricated by micromachining techniques can be used for high-density data storage, nanopatterning, etc., where contact-scanning and thermal-plastic nanowritings are frequently implemented on the surface of a polymer thin-film such as polymethylmethacrylate (PMMA). In such kind of applications, micro-nanofriction effects, e.g., contacting-size and temperature effects of the tip/film friction system, will largely influence the performance of the applications. To elucidate the effects, present research fabricates a monolithically integrated probe array that comprises three scanning probe microscopy cantilever-tip probes with different tip radii of tens of nanometers, submicrometers and microns, respectively. The tip is enabled an electric-heating function by integrating a heating resistors on the tip. Using the tips, the tip/film friction experiment shows an obvious contacting-area effect. Within a wide temperature range, the friction signal and the normal force load exhibit a nonlinear relationship for the nanoradius tip but a linear relationship for the submicron tip. With the heated tips, the experiment directly reveals significant size effects on friction and adhesion behaviors. It is found that the glassy transition of the PMMA film can be characterized using the submicron tip, while the nanotip is suited to detect the secondary beta transition process. By fitting the experimental data into a power law with apparent friction coefficient included, the temperature-effect combined size effect of the micronano tip/polymer friction is modeled and discussed.