Application Snapshot - Advantages For Using Atomic Force Microscopes For Polished Surfaces
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Directly Visualize Surface Texture
An AFM gives high contrast on extremely flat samples and is ideal for visualizing the surface topography of polished surfaces.
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Measure Depth of Subnanometer Polish Marks
Because an AFM directly measures a 3D topogram of the polished sample’s surface, the depth of polish marks less than .05 nm are measurable.
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Measure NanoScale Surface Roughness
The noise floor of an AFM can be less than .03 nm (30 picometers) enabling surface roughness of polished surfaces with roughness < 0.1 nm to be measured.
AFM image of a Polished Diamond Surface
Example Images
1 x 1 micron AFM image of a Polished Diamond Surface measured in vibrating mode.
Sample courtesy of Great Lake Crystal.
Line profile polish marks left on a diamond coated surface. The depth of the polish marks designated by the two arrows is 0.215 nm. Polish marks with a depth of less than 0.05 nm are readily measured with an AFM.
2 x 2 micron image of a polished Si wafer with an oxide film on the surface, measured with vibrating mode.
Surface texture parameters calculated directly from the AFM image of the polished Si wafer scanned in vibrating mode. The surface roughness (Sa) is 0.262 nm. Surface roughnesses of less than 0.1 nm are readily measured with an AFM.
Technical
Keywords
In the AFM instrument, a sharp probe is scanned over a surface. The motion of the probe is captured by a computer, an the line profiles are used to create a surface topogram.
The Z noise in an AFM establishes the smallest features that can be measured. Z noise is calculated from a scan taken with XY motion turned off. The Z noise is affected by the design of the AFM stage, and external structural and sound vibrations.
