Pacific Nanotechnology Inc.

AFM for Nano-Surface Texture/Roughness

Examples of Sample Texture Measurements

Visualization:
Often it is difficult to fully characterize surface texture without direct visualization of a surface. Atomic force microscopes are well suited for visualization of surface texture, especially when the surface feature sizes are far below one micron. Illustrated below is the surface texture of a piece of commercially available recording tape.

Figure 2: 10 µm × 10 µm AFM image of commercially available magnetic tape showing the surface texture. The maximum Z scale on this image is 48.5 nanometers. Such images facilitate a visual inspection of surface roughness and texture.

Line Roughness:
After acquiring an AFM image it is possible to measure the 1-D surface roughness on a line in the horizontal or vertical direction in the image. After identifying the line for the measurement, a computer calculates all of the relevant parameters. Below is an illustration of the 1-D surface roughness measured on a polymer film.

Figure 3: Line surface roughness of a polymer film showing a value for Ra of about .71 nanometers. There are larger features on the image, as large as 18.39 nanometers, but they are not included in the calculations of these line roughness parameters.

Area Roughness:
Optimal characterization of surface texture is often expressed with area roughness calculations that are made on the entire surface. Surface roughness calculations are similar to line roughness calculations but they include data in the x and y plane of the surface.

Figure 4: This is a 1 ÷m X 1 ÷m image of a bare silicon wafer image with the Nano-RT AFM system. The area roughness values shown are for the entire image.