Very High Resolution Calibration Reference for AFM an SEM
![](http://wp.asmicro.com/wp-content/uploads/2018/02/150-2D_3um_scan-MR.jpg)
![](http://wp.asmicro.com/wp-content/uploads/2018/02/150-2D_average_height_profile.gif)
The smooth bumps produce a very regular height profile that gives improved measurement precision.
The bump height is about 90 nm. This specimen is not recommended as a height reference because it is not easy for the standard AFM probes to reach the substrate below the level between the bumps.
The above scans were made in TappingMode.
![](http://wp.asmicro.com/wp-content/uploads/2018/02/150-2D_5um_ContactModeScan-MR-1.jpg)
During scanning in contact mode using a 0.5 N/m SiN cantilever, we did not notice any surface or tip wear affecting the image.
SEM Characteristics
A leading independent analytical lab examined a Model 150-2D specimen in a Hitachi S4700 FE-SEM. The specimen was mounted using a conductive carbon adhesive tape and easily imaged at high resolution. Four accelerating voltages were used: 1, 5, 10, and 20 kV. No significant charging was observed at any voltage.
High magnification images
The following images were captured with a magnification setting of 100 kX. The appearance of the bumps changes with accelerating voltage as expected. At 1 kV, the electrons penetrate only a short distance, giving a surface sensitive image that shows the rounded topography of the bumps. At 5 kV, the bumps have a flat appearance. The edges appear brighter at 10 kV and at 20 kV, the edge contrast is very pronounced.
![](http://wp.asmicro.com/wp-content/uploads/2018/02/150-2D_1kV_100kx-crop-LR.jpg)
![](http://wp.asmicro.com/wp-content/uploads/2018/02/150-2D_5kV_100kx-crop-LR.jpg)
![](http://wp.asmicro.com/wp-content/uploads/2018/02/150-2D-10kV-100kx-crop2-LR.jpg)
![](http://wp.asmicro.com/wp-content/uploads/2018/02/150-2D_20kV_100kx-crop-LR.jpg)
Medium Magnification
At 5 kX, the individual bumps were still well-resolved. Large fields of view show how few defects are present. The most common defects are single missing bumps or a single extra bump inserted between lattice positions. Two vacancies are present in the image shown here.
![](http://wp.asmicro.com/wp-content/uploads/2018/02/150-2D_20kV_5kx-crop-LR.jpg)
After completing the work, the analyst said: “It was nice to have something with sharp features.”