Micromachined Photoplastic Probes for Scanning Probe Microscopy

Scanning Probe Microscopy (SPM) is a well-established technique for surface analysis, but batch-fabricated, low-cost probes still remain a challenging issue. The design and fabrication of entirely photoplastic probes for Scanning Force Microscopy (SFM) have been developed and used for imaging DNA molecules. Using a polymer for the cantilever facilitates the realization of mechanical properties that are difficult to achieve with classical silicon technology. Single lever and cassettes of multiple single-lever probes are presented. The probes are made of an epoxy-based photoresist, which can be structured by standard photolithography and molding techniques. The fabrication process is a simple batch process in which the integrated tips and the levers are defined in one photolithography step. Imaging soft, condensed matter with photoplastic levers, which uses laser beam deflection sensing, exhibits a resolution that compares well with that of commercially available silicon cantilevers. A similar fabrication technique was also developed to fabricate photoplastic tips for Scanning Near-field Optical Microscopy (SNOM) that are to be attached to optical fibers. This technique allows optical apertures to be integrated at the end of the well-defined tip directly by probe fabrication, without the need for any post-processing for the aperture formation. Simple fabrication, as well as topographical and optical imaging with such probes, demonstrate the potential of photoplastic-based probes for AFM and SNOM applications.

Keywords: SFM probe, SNOM probe, SU-8, photoplastic, micromachining