Fabrication and characterization of diamond AFM probe integrated with PZT thin film sensor and actuator

Abstract In order to develop a diamond probe with a piezoelectric sensor and actuator for atomic force microscope (AFM), we fabricated lead zirconate titanate (PZT) thin film on a diamond thin film substrate and examined its piezoelectric properties. The PZT thin film was sputtered at room temperature and then annealed to obtain a perovskite structure. After rapid thermal annealing at temperature ramp rate of more than 10 °C/s and at temperatures of more than 500 °C in a nitrogen (N2) ambient, the PZT thin film fabricated on flat Si substrates showed high piezoelectric constant, d31, of about −90 pC/N, as well as in an oxygen (O2) ambient. On diamond thin film substrates, the value of piezoelectric constant was as low as about −20 pC/N due to rough surface of the diamond film. After a poling treatment, however, its piezoelectric constant improved to about −65 pC/N. For realization of a PZT sensor and actuator on a diamond cantilever, the PZT thin film was also successfully patterned by reactive ion etching (RIE) in sulfur hexafluoride (SF6) plasma using a platinum (Pt) upper electrode layer as an etching mask without any damage on the diamond layer. Based on the fabrication and patterning of PZT thin film together with microfabrication techniques of diamond film formed by chemical vapor deposition (CVD), we demonstrate the diamond AFM probe of 150 μm in length, 50 μm in width, and 5 μm in thickness with a PZT sensor and actuator of 1 μm in thickness. The resolution of image sensing and actuation force were estimated to be about 0.4 nm at a resolution of charge measurement of 1×10−15 C, and 17 μN at an applied voltage of 8 V, respectively.