Surface Roughness (Ra)

Surface roughness measurements are made with a Zygo NewView 100 3D Imaging Surface Structure Analyzer using white light interference microscopy.

Example 1:  The surface roughness (Ra) of a metallic film on a silicon wafer was measured to be 0.004 μm over an area of 90 by 60 μm.  The peak to valley difference is 0.068 μm in this area.

Metal film on Si Wafer, low roughness

In the upper left image, the height is color-coded. The Ra (surface roughness) value along the horizontal line shown is 0.003 μm, with the height along that line shown in the lower left image. The Ra in the entire 0.09mm x 0.06mm area examined is 0.004 μm. The 3-dimensional plot of the image in the upper right displays the sample height directly.  The image in the lower right is an optical image of the surface.

Example 2: The surface roughness (Ra) of a metallic film on a silicon wafer is 0.011 μm in the 90 x 60 μm area examined.  The peak to valley difference is 0.412 μm

Surface Roughness of a Metal Film on a Silicon Wafer, medium roughness

Example 3: The surface roughness (Ra) of a metallic film on a silicon wafer is 0.077 μm

It is common to examine larger areas on rougher sample.

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