Integration of sharp silicon nitride tips into high-speed SU8 cantilevers in a batch fabrication process.

Nahid Hosseini,Oliver Peric,Jonathan D Adams,Matthias Neuenschwander,Santiago H Andany,Georg E Fantner

doi:10.3762/bjnano.10.226

Nahid Hosseini, Oliver Peric + Show 4 more

Open Access

https://doi.org/10.3762/bjnano.10.226

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Abstract

Employing polymer cantilevers has shown to outperform using their silicon or silicon nitride analogues concerning the imaging speed of atomic force microscopy (AFM) in tapping mode (intermittent contact mode with amplitude modulation) by up to one order of magnitude. However, tips of the cantilever made out of a polymer material do not meet the requirements for tip sharpness and durability. Combining the high imaging bandwidth of polymer cantilevers with making sharp and wear-resistant tips is essential for a future adoption of polymer cantilevers in routine AFM use. In this work, we have developed a batch fabrication process to integrate silicon nitride tips with an average tip radius of 9 ± 2 nm into high-speed SU8 cantilevers. Key aspects of the process are the mechanical anchoring of a moulded silicon nitride tip and a two-step release process. The fabrication recipe can be adjusted to any photo-processable polymer cantilever.

Highlights

Atomic force microscopy (AFM) cantilevers have been developed for numerous applications since the invention of scanning probe microscopy (SPM) [1]
Quality and accuracy of an AFM image strongly depend on the tip geometry since the image topography is the convolution of the surface topography and the cantilever tip geometry [2]
Tip sharpness measurements have been performed for 20 cantilevers, and reveal an average tip sharpness of 9 ± 2 nm

Summary

Introduction

Atomic force microscopy (AFM) cantilevers have been developed for numerous applications since the invention of scanning probe microscopy (SPM) [1]. Quality and accuracy of an AFM image strongly depend on the tip geometry since the image topography is the convolution of the surface topography and the cantilever tip geometry [2]. AFM images with tip artefacts are of reduced quality and can seriously mislead users [4]. New fabrication methods have enabled increased tip sharpness and uniformity, so that commercial AFM cantilevers have a standard tip quality. A range of specialized AFM techniques require custom tip designs, including high-speed AFM [5,6], high-resolution electrochemical and nanoelectrical imaging [7,8], Raman spectroscopy [9], nanoindentation [10], nanomechanical machining [11], plasmonic applications [12,13] and microscale grapping [14]

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