Squeeze Film Air Damping in Tapping Mode Atomic Force Microscopy.

Yang Zhao,Liansheng Zhang,Qiangxian Huang,Yong Zhang,Rongjun Cheng

doi:10.3390/mi8070226

Yang Zhao, Liansheng Zhang + Show 3 more

Open Access

https://doi.org/10.3390/mi8070226

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Abstract

In dynamic plowing lithography, the sample surface is indented using a vibrating tip in tapping mode atomic force microscopy. During writing, the gap between the cantilever and the sample surface is very small, usually on the order of micrometers. High vibration frequency and small distance induce squeeze film air damping from the air in the gap. This damping can cause variations in the cantilever’s vibrating parameters and affect the accuracy of the nanoscale patterning depth. In this paper, squeeze film air damping was modeled and analyzed considering the inclined angle between the cantilever and the sample surface, and its effects on the resonant amplitude and damping coefficient of the cantilever were discussed. The squeeze film air damping in the approaching curve of cantilever was observed, and its effect on fabricating nanopatterns was discussed.

Highlights

Tapping mode atomic force microscopy (AFM)-based nanolithography has been widely used for structuring materials and fabricating nanopatterns [1,2]
In the Dynamic plowing lithography (DPL) process, the cantilever—which is driven by a dither piezo actuator—vibrates near its resonance frequency
The image of the sample topography can be obtained by recording and regulating the modulation amplitude applied to the dither piezo that drives the cantilever oscillations

Summary

Introduction

Tapping mode atomic force microscopy (AFM)-based nanolithography has been widely used for structuring materials and fabricating nanopatterns [1,2]. The distance between the cantilever and the sample surface during the nanolithography process is very small, and usually on the order of micrometers [8]. Combining the Lorentz equation and the theory of mechanics, Leveque [12] studied the effect of air damping on cantilever amplitude when the cantilever operates at low frequency.

Results

Conclusion