Atomic force microscope anodization lithography using pulsed bias voltage synchronized with resonance frequency of cantilever

Abstract

An applied bias voltage between the atomic force microscope tip and the substrate is one of the important factors related to the growth of oxide patterns. A pulse modulator was used to apply a pulsed bias voltage that synchronizes with the resonance frequency of the cantilever between the tip and the substrate in tapping mode. The height of the protruded oxide structure was increased for short duration times of the pulsed bias due to the reduction of built-up space charge in oxide. The aspect ratio of patterns using pulsed bias voltage was about two times higher than that using continuous bias voltage. This study revealed that the pulsed bias has an advantage for obtaining a higher aspect ratio pattern than the continuous bias by reducing the effect of space charge in oxide.

A study of the transient current during the formation of titanium oxide nanodots by AFM anodic oxidation

“…It has been reported that the use of pulsed bias voltages produces oxide structures with higher aspect ratio because it changes the kinetics of the oxidation [31,[34][35][36]. The main advantage of using the pulsed bias voltage is the neutralization of trapped charges at the oxide/Ti interface during the idle part of the cycle.…”

Scanning Probe Oxidation Lithography on Ta Thin Films

“…Recent study with a shorter duration time of pulsed voltage has proved to be able to fabricate significantly improved high aspect ratio oxide compared to the conventional AFM anodization lithography process using continuous bias. 36 For electrical characterization, a 1 × 1 m 2 TaO x layer with oxide height of 2.3 nm was formed on a Ta film to measure the electrical properties of TaO x . The 3D surface topography and the spreading surface resistance image (SRI) of the TaO x layer on this Ta film are shown in Figures 6(a) and (b) respectively.…”

Engineering nanostructures at surfaces using nanolithography

“…Instead electrochemical reactions are carried out simply by the application of a voltage between the tip and the substrate, creating a current through the meniscus. This technique is often referred to in the literature as 'anodization lithography' [256][257][258][259] or 'local oxidation nanolithography' [260]. However, reductive reactions can be initiated on surfaces with the delivery of a precursor 'ink' to the surface along with the application of a voltage between the tip and the substrate [261][262][263] and this is known as 'electrochemical DPN'.…”