By Karlsruhe Nano Micro Facility (KNMF)
Atomic Force Microscopy Since its invention in 1986, the atomic force microscope (AFM) has become widely used for inspecting sample surfaces down to the atomic scale. The experimental setup of an AFM is based on a simple concept: it detects forces acting between a sample surface and a sharp tip mounted on a soft leaf spring, known as a cantilever. A feedback system controls the vertical (z) position of the tip on the sample surface, maintaining a constant deflection of the cantilever (and thus a constant force between the tip and the sample). By moving the tip relative to the sample in the x–y plane using piezoelectric drives, the actual z-position of the tip is recorded as a function of the lateral x–y position with high precision. The resulting data represent a map of equal forces, which can be interpreted as the surface topography. The lateral resolution (x–y) depends on the tip radius, which ranges from 10 to 20 nm, while the vertical resolution (z) is typically better than 1 nm. For specific cantilevers, the lateral resolution can be less than 1 nm, depending on the tip radius and geometry. Features - Measurements in different modes and techniques – Contact mode – Dynamic modes (tapping, AM-mode,...) – Friction force microscopy (FFM) – Magnetic force microscopy (MFM) – Electrostatic force microscopy (EFM) – Kelvon probe force microscopy (KPFM) – Nanolithography option – Nanoindentation option - Large sample sizes (up to 8’’ wafer) - Large scan ranges (up to 800 μm x 800 μm) - Measurement in ambient conditions and fluids - Combination of AFM and optical microscopy - With motorized stages installed, the instruments can perform correlated measurements - Sample heating and cooling during scanning (-30°C up to 200°C) Limitations/constraints - Sample should be smooth and flat - Maximal sample height is restricted to 2 cm
