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DS: Fachverband Dünne Schichten

DS 52: Ion and Electron Beam Induced Processes

DS 52.2: Talk

Thursday, March 10, 2016, 17:15–17:30, H11

Milling and imaging techniques at the helium ion microscope for sub 2 nm nanopore fabrication — •Daniel Emmrich¹, Emanuel Marschewski¹, Jani Kotakoski², Achim Nadzeyka³, Frank Nouvertné³, Jannik Meyer², André Beyer¹, and Armin Gölzhäuser¹ — ¹Physics of Supramolecular Systems, Bielefeld University, Germany — ²Physics of Nanostructured Materials, University of Vienna, Austria — ³Raith GmbH, Dortmund, Germany

The helium ion microscope (HIM) is a charged particle microscope employing helium ions for probing the sample. In the low dose regime, the HIM operates as microscope, high doses enable material modification and sputtering. Compared to conventional focussed ion beams (FIB) using metal ions like gallium, the HIM offers a very small focal spot size down to 0.35 nm and a strongly localized sputter interaction with the material. We employ the HIM for both milling nanopores in free standing membranes as well as for the inspection of pores. The helium ion beam with its unique properties overcomes the resolution limit of conventional FIB tools as we show in a comparison with a high resolution gallium FIB. We investigated three different materials: 30 nm thick silicon nitride, graphene and 1 nm thick carbon nanomembranes (CNM) made from aromatic self-assembled monolayers by electron-induced cross-linking. By HIM milling and imaging we can detect smallest nanopores at 3 nm diameter in all membranes. Further studies on CNM with an atomic resolution STEM revealed even nanopores with diameters of less than 2 nm made by ion beam exposure.