Ion-beam-sputter deposited titanium nitride thin films for conductive atomic force microscope probes

Abstract

We investigated the application of titanium nitride (TiN) thin film as the coating material for atomic force microscope (AFM) probes. TiN exhibits high hardness, chemical stability, and relative high electrical conductivity that are ideal for protective coating of conductive AFM probes. The TiN thin films were deposited by ion beam sputter deposition (IBSD) using a Ti target with nitrogen as the reactive gas and argon as the carrier gas. The nitrogen partial pressure affected the composition, crystallinity, and resistivity of TiN films — increase of N2/Ar flow rate ratio reduced the TiN composition and crystallinity. Consequently, the electrical resistivity of TiN coating increased. The profiles of AFM probe tips before and after TiN thin film (~30nm) deposition were characterized by scanning electron microscopy. The tribological properties of TiN coated probes were evaluated by AFM scans and hard-contact electrical measurements; the performances were compared with commercial probes with metal coatings.In this work, we reported on the performance of TiN thin films as a functional coating for conductive AFM probes, and discussed the relation between electrical/tribological properties and IBSD process parameters for TiN thin films.