A New Correlative Microscopy Platform Integrating AFM with in situ SEM

We present a highly integrated correlative microscopy platform designed to incorporate a wide range of imaging and measurement capabilities normally found in two or more microscopy workstations [1]. The system design includes an Atomic Force Microscope (AFM) employing self-sensing cantilever technology [2] and a miniature Scanning Electron Microscope (SEM) column equipped with a Thermal Field Emission (TFE) source. A pumping system provides the necessary Ultra-High-Vacuum (UHV) environment to operate the SEM column and evacuate the sample chamber to High Vacuum (HV). The instrument modular architecture allows easy expansion of the system capabilities to include additional measurement probes and measurement option upgrades. A top port into the sample volume can be used to upgrade the system to include an Energy Dispersive X-ray Spectroscopy (EDS/EDX) system. Additional ports are also available for a variety of custom user experiment expansions. The platform employs a compact sample chamber for ease of evacuation. In addition, a three-axis sample stage, a trunnion capable of tilt and an AFM stage provide for a unique experiment capability inside the FusionScope sample chamber. For instance, with profile-view an 80-degree tilt of the combined stage and AFM scan head – the user can guide and position the AFM tip quickly and precisely, even on complex and challenging sample morphologies (see Fig. 1). At the heart of the instrument lies a truly correlated user experience, and key to this is its correlated coordinate system. This coordinate system ties together the AFM and SEM operations so that all measurements and tracking are using the same exact “map” to measure user samples and locate specific areas of interest. This also allows for automated features in the FusionScope software, such as locating an area of interest using SEM and then directing the FusionScope to automatically find that same area with the AFM. Fig. 2 shows data taken from an off the shelf commercial razor blade for quality assurance purposes. The SEM profile-view allows a careful approach and landing of the AFM tip on the razor blade edge. The data taken in contact mode shows the apex curvature for different location along the razor edge. Zero (left) and eighty (right) degrees trunnion tilt configurations. With an eighty-degree tilt it is possible to visualize and precisely position the AFM tip on regions of interest even for challenging morphologies. SEM view of an AFM tip on a razor blade (left and center). AFM data of the razor blade sharpness (right).