For nanoscale electrical characterization applications, a key requirement is the availability of cantilevers with nanoscale conductive tips. Unfortunately, none of the conventional technologies allow the fabrication of probes featuring low wear rates and reliable conduction together with the requirement of small tip radii.
We have proposed the use of platinum silicide (PtSi) probes to address this problem [2011-1, 2009-2, 2009-5, 2009-12]. These tips have small radii and conductivity close to commercial PtIr coated probes, but also have an outstanding mechanical wear-out behavior and sustained electrical contact quality.
We are also researching encapsulated conductive probes with conductive cores comprising of PtSi and an insulating encapsulation consisting of SiO2 [2009-6]. These probes are significantly wear-resistant owing to their large tip–sample contact area and can also sustain high currents.
The large tip–sample contact area and the subsequently increased adhesive force also motivate our use of these probes in the retraction mode, where tip–sample contact is maintained only by virtue of the adhesive forces [2009-9]. This further enhances the durability of these probes, making them valuable tools for nanoscale electrical characterization (Fig. 1).
Figure 1. Conductive-probe technology based on platinum silicide (PtSi) and encapsulated PtSi tips.