Electric field and tip-surface interaction dependence in nanopattern deposition by electropulsed scanning probe microscopy

摘要

The reduced dimensions of novel integrated devices and systems stresses the need for new nanopatterning techniques. We showed that metallic individual pixels, pixilated patterns and smooth patterns can be obtained by applying negative voltage pulses to a tip coated with a CoCr metallic film while scanning in tapping mode AFM. Electropulsed AFM deposition at different negative pulse voltages and frequencies, and different tip-surface interaction conditions is reported in this work. Deposits with pixel diameter between 21 and 34 nm and height between and 2-3 nm were obtained by applying -12 V pulses to the tip. When the pulse voltage goes to -16.8 V the pixel diameter increases to 90 nm and height exceeds 4.0 nm. At 10 Hz pulse frequencies the patterns obtained are pixilated, resulting in high surface roughness (Ra=0.44 nm). At 20 Hz the deposited pixels are fully merged, resulting in flat surfaces with low roughness (Ra=0.19 nm). For higher pulse frequencies up to 60 Hz the roughness remains between Ra=0.17 and Ra =0.22 nm. The deposited thickness increases from values around 1.0 nm at -7 V pulse voltage to values around 4 nm at -16.5 V. By properly tuning the amplitude setpoint for a new tip a similar deposited thickness dependence can be obtained. The deposited thickness increases with the tip-surface interaction.