Combining AFM with FIB/SEM in Nanofabrication

Activity: Talk or presentationInvited talk at conference or symposiumScience to science

Description

The ongoing trend towards miniaturization of components in electronics and other technologies is driving the development of suitable fabrication- and analysis tools for nanoscale structures. Versatile tools in this context are dual beam microscopes that combine a Scanning Electron Microscope (SEM) with a Focused Ion Beam (FIB). These beams enable nanofabrication via subtractive structuring (FIB milling, etching) and additive manufacturing (Focused Particle Beam Induced Deposition), as well as obtaining a variety of information about the sample (e.g. different imaging modes, X-ray spectroscopy). In contrast, for complementary information such as the quantitative sample morphology in 3D, mechanical, electrical and magnetic surface properties, Atomic Force Microscopy (AFM) is often the method of choice. While usually both techniques are done one after the other, for many questions it is advisable or even partly unavoidable to apply FIB/SEM and AFM in situ, in parallel or simultaneously. Therefore, integrating an AFM into a FIB/SEM chamber can provide new insights that are not accessible with stand-alone microscopes. In this contribution we first discuss the benefits of AFM measurements in vacuum compared to ambient conditions. In a first use cases we present 3-dimensional reconstructions of sample volumes where the physical properties (e.g. mechanical, magnetic, electrical) can be mapped for each layer using advanced AFM modes and then correlated with information obtained by FIB/SEM. The individual layers can be produced either by FIB-slicing (subtractive tomography) or by layer-by-layer growth (additive tomography). Figure 1 shows subtractive tomography of polymer beads in an aluminum matrix, where the stiffness in each FIB slice was measured by the AFM. An example of additive tomography is given in Figure 2, where the electron beam was used to deposit single layers of material (FEBID), while the AFM monitored the layer-by-layer growth in situ [1]. In other applications, the SEM can be used to select the region of interest and precisely position the AFM for mechanical testing of nanostructures. In addition, we present correlative characterization of FIB cuts in a multilayer system combining FIB-SEM-EDX and AFM techniques. Again, we go beyond simple AFM based height and phase imaging and use more advanced AFM modes (magnetic/electric force, conductive AFM) to obtain comprehensive information of the sample. However, such AFM modes require specialized nanoprobes, therefore, we briefly outline the fabrication route of such advanced AFM tips via 3D-nanoprinting. The selected examples all demonstrate the advantages of correlative microscopy of a FIB-SEM dual beam microscope with an in situ AFM.
Period4 Sep 20229 Sep 2022
Event title16th Multinational Congress on Microscopy : 16MCM
Event typeConference
LocationBrno, Czech Republic
Degree of RecognitionInternational

ASJC Scopus subject areas

  • General Materials Science

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Basic - Fundamental (Grundlagenforschung)