Scanning Probe Oxidation Lithography on Ta Thin Films

Abstract

A Semi-Contact Scanning Probe Lithography Technique (SC-SPL) has been applied to create nano-oxide patterns on Ta thin films grown by DC magnetron sputtering method on SiO2/Si substrates. The height and linewidth profiles of nano-oxide lines created by a conductive AFM tip on Ta film surfaces were measured as a function of applied voltage, oxidation time, humidity, and tip apex curvature. The AFM surface measurements show that the height of the oxides increases linearly with increasing voltage; but there was no oxide growth, when less than 4 V was applied even at 85% relative humidity. Electrical measurements were performed and the resistivities of the TaOx layer and Ta film were obtained as 5.76 × 108 and 1.4 × 10−5 Ohm-cm, respectively.

Local oxidation nanolithography on Hf thin films using atomic force microscopy (AFM)

“…The transverse resistivity of the HfO x layer was found to be 4.284×10 9 cm which is in agreement with the value reported for sputtered HfO 2 films in the literature [25]. When this result is compared with our previous study [24], it can be understood that HfO x is more resistive than TaO x (resistivity of 5.76 × 10 8 cm), as created by the method of AFM local oxidation.…”

“…The 3D surface topography and the thickness profile of this pattern can be seen in figures 6(a) and (b). To obtain the current voltage characteristics of the protrusion of HfO x and Hf film, the DLC coated conductive AFM tip was allowed to touch the HfO x or Hf surface in contact mode as shown in figure 6(a) and two terminal electrical measurements were performed [24]. The distance between the conductive tip and the counter electrode was kept at 5 mm.…”