http://kbose.weebly.com/uploads/1/0/4/9/10492046/force-distance_curves_by_atomic_force_microscopy_1.pdf

Force-distance curves by atomic force microscopy

A scanning probe microscope having numerous advantages is disclosed. Respective scanning force and scanning tunneling probes are removably mounted in the head using kinematic mounting techniques so that they may be substituted for one another without the need to adjust the cantilever deflection sensor. A linear position-sensitive photodetector in the deflection sensor eliminates further the need for adjustments. A motorized, non-stacked x,y coarse movement stage is kinematically positioned with respect to the base and features a minimized mechanical loop to reduce thermal and vibrational effects on the position of the sample. A z coarse movement stage positions the head kinematically with respect to the base and includes a motorized drive means which allows the height, tilt and pitch of the probe to be adjusted. The scanner includes x,y and z sample position detectors which provide an accurate measurement of the position of the sample with respect to the probe. The z position detector provides an output which is exclusive of sample tilt and which may be used as an output of the scanning probe microscope. The outputs of the x,y and z position detectors may also be connected in feedback loops with the controller to improve the performance of the scanning probe microscope.

Scanning probe microscope

Nonlinearities inherent in the piezoelectric actuators used in high‐resolution scanning probe microscopies limit the usefulness of the instruments for precision dimensional measurements of submicrometer to micrometer scale structures. These nonlinearities can result in images where the scale changes by over 40% from one region of the image to another. This paper describes a simple two‐axis optical beam displacement sensor that is used to accurately measure the (x,y) position of a piezoelectric tube scanner used in an atomic force microscope. This sensor has a noise level of 6.1 Arms over a frequency range of 0.5 Hz–1 kHz and a stability of about 200 A over a 30‐min period. Two different methods were used to correct the scans: postimaging software image correction and real‐time feedback scan correction. The software method allows fast imaging and does not alter the control of the microscope, but requires postimaging image processing. It also loses some image information because of interpolation errors and ...

Optical scan‐correction system applied to atomic force microscopy

Advances in Scanning Force Microscopy for Dimensional Metrology

The present invention allows for calibration of a scanning probe microscope under computer control. The present invention comprehends either the removal of nonlinear artifacts in the microscope output data after measurement has been taken (a off-line process), or the correction of nonlinear movements in the microscope scanner such that the scanner moves in a linear fashion during measurement (a realtime process). The realtime process may be operated in both an open-loop and a closed-loop process. The processes of the present invention uses an average cross-section of the scan in order to simplify the calculation and to improve the signal-to-noise ratio. Interpolation methods and centroid calculations are used to locate features on the scanned sample to subpixel precision. Comparison of the measured scan feature positions with the known topography of the scanned calibration specimen enable the present invention to assemble a calibrated length scale which may be used to correct individual feature positions in a full two-dimensional scan, each scan line in a two-dimensional image, or an average cross-section of the two-dimensional scan.

High precision calibration and feature measurement system for a scanning probe microscope

A serious impediment to precision metrology with scanning probe microscopes is the unreproducible, nonlinear behavior of the piezo ceramic actuators. We have developed a simple solution to the problem by measuring the position of the scanning head with capacitors. The circuit monitoring the gap between the plates has a linear response with slope 12 μm/V and noise of 0.1 nm/(Hz)1/2. The linearity of the system is verified by comparing the capacitor output with a scan of a grating that is periodic in two dimensions. We analyze the errors associated with the technique and show how to reduce them to acceptable levels.

G. L. Miller

Papers

A scanning tunneling microscope with a capacitance‐based position monitor