State of the art three-dimensional atomic force microscopes (3D-AFM) cannot measure three spatial dimensions separately from each other. A 3D-AFM-head with true 3D-probing capabilities is presented ...in this paper. It detects the so-called 3D-Nanoprobes CD-tip displacement with a differential interferometer and an optical lever. The 3D-Nanoprobe was specifically developed for tactile 3D-probing and is applied for critical dimension (CD) measurements. A calibrated 3D-Nanoprobe shows a selectivity ratio of 50:1 on average for each of the spatial directions
,
, and
. Typical stiffness values are kx = 1.722 ± 0.083 N/m, ky = 1.511 ± 0.034 N/m, and kz = 1.64 ± 0.16 N/m resulting in a quasi-isotropic ratio of the stiffness of 1.1:0.9:1.0 in
:
:
, respectively. The probing repeatability of the developed true 3D-AFM shows a standard deviation of 0.18 nm, 0.31 nm, and 0.83 nm for
,
, and
, respectively. Two CD-line samples type IVPS100-PTB, which were perpendicularly mounted to each other, were used to test the performance of the developed true 3D-AFM: repeatability, long-term stability, pitch, and line edge roughness and linewidth roughness (LER/LWR), showing promising results.
Monte Carlo methods are appropriate for determining the manufacturing accuracy and measurement uncertainty for the calibration of mass standards using sorption, duplex and buoyancy artefacts that are ...referred to as transfer artefacts. Systematic influences and their application-specific measurement uncertainty can be calculated for the important parameters mass, surface area and volume. Since accurate volume measurements are complex, the evaluation of the uncertainty contribution is important. The input variables of the simulations result from the specified manufacturing tolerances as well as from the measurement uncertainties of the coordinate measuring machines employed. The developed model allows the transfer artefacts described to be calculated with a uniform approach according to the specifications of the GUM. Results for silicon transfer artefacts with a nominal mass of 1 kg are presented and discussed.
Monte Carlo methods are appropriate for determining manufacturing accuracy or measurement uncertainty for the calibration of mass standards such as sorption, duplex and buoyancy artefacts, which are ...referred to as transfer artefacts. Systematic influences and their application-specific measurement uncertainties can be calculated for three important parameters: mass, surface area and volume. The input variables of the simulations yield from the specified manufacturing tolerances as well as from the measurement uncertainties associated with the input variables related to the coordinate measuring machines employed. The model developed here allows the transfer artefacts shown to be calculated with a uniform approach in accordance with the specifications of GUM. Results for silicon transfer artefacts with a nominal mass of 1 kg are presented and discussed.
In this article a new offline method for correcting non-linear drift in all three dimensions (3D) is presented. Using this method, a sample region is measured in multiple sub-measurements, each with ...increased sampling distance and thus reduced measurement time. The datasets of the sub-measurements are aligned using a point-to-plane iterative closest point algorithm to reconstruct and correct the 3D drift. Afterwards, the corrected datasets are fused into a single dataset. Compared to conventional drift-correction methods, the new method has the advantages of drift correction in full 3D with higher temporal resolution, less extra measurement time and data redundancy, as well as high application flexibility (e.g. compatibility to non-raster sampling). However, the resulting dataset might have slightly decreased resolution. If a high-resolution low-drift dataset is required, the method can be applied in an extended way, where an additional high-resolution measurement is taken whose drift can be corrected by the aforementioned dataset generated by data fusion. Two experimental measurements and a simulation study have been carried out in a new low-noise 3D atomic force microscope, showing great application potential of the proposed method.
•We present a study in characterizing tip wear of a high speed AFM on four different samples and under different measurement conditions. Our results indicate the dominance of tip breakage in ...high-speed AFM measurements.•To understand the mechanism of tip breakage, we modelled and simulated the tip-sample interaction. The results indicate that the tip-sample interaction force increases dramatically in measurement scenarios of steep surfaces.•Detailed methods for tip characterization and wear test procedures are presented in the paper.
Tip abrasion is a critical issue particularly for high-speed atomic force microscopy (AFM). In this paper, a quantitative investigation on the tip abrasion of diamond-like-carbon (DLC) coated tips in a high-speed metrological large range AFM device has been detailed. Wear tests are conducted on four different surfaces made of silicon, niobium, aluminum and steel. During the tests, different scanning speeds up to 1 mm/s and different vertical load forces up to approximately 33.2 nN are applied. Various tip characterization techniques such as scanning electron microscopy (SEM) and AFM tip characterizers have been jointly applied to measure the tip form change precisely. The experimental results show that tip form changes abruptly rather than progressively, particularly when structures with steep sidewalls were measured. This result indicates the increased tip breakage risk in high-speed AFM measurements. To understand the mechanism of tip breakage, tip-sample interaction is modelled, simulated and experimentally verified. The results indicate that the tip-sample interaction force increases dramatically in measurement scenarios of steep surfaces.
Automated optical inspection is an important test procedure in electronic circuits assembly. Frequently 3d information is required and laser light sectioning sensors are often applied. However, some ...effects complicate the reliable automatic detection of the shape of such assemblies and their components. The packages of electronic components often are made of black plastics or ceramics so that the intensity available for the optical detection is quite low, especially in comparison to the surface of the PCBs where the components are mounted on. In addition due to rough surfaces of the components and the coherence length of the laser light speckle structures arise. In the work presented here a piezo actuator is used to oscillate the illuminating laser lines along the direction of the lines. The aim is to reduce the visibility of the speckle structures by averaging while maintaining the geometrical shape of the lines. In addition, image processing methods like segmentation and skeletonization are used to allow the detection of the shape of components and assemblies also if materials with distinct differences in the reflectivity are involved. Investigations include the influence of the parameters amplitude and frequency of the piezo actuator.
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