Scan line profile determined by the tip shape
[ OMCL-AC160TS / 240TS- series ]
As can be seen in the illustration below, a tetrahedral tip is located at the exact end of the cantilever.
The finite tip shape will determine the Scan line profile as in the illustrations below.
The tip profile is symmetric with a tip angle of 35 degrees from its front side (see left below). The side tip profile is asymmetric with a tip angle of 35 degrees. When the cantilever chip is attached to a chip holder in your AFM with an angle, about 10 degrees, the asymmetry of the scan line profile is improved (see right below).
Top of the tetrahedral tip becomes thinner because of an oxide sharpening process. The tip angle around a few hundreds of nanometer down from the top, is about 15 to 25 degrees (see below).
The following is an SEM picture of a Tetrahedral tip observed from the side of a cantilever free end. The tip half angle is less than 18 degrees. Compare the tip with the yellow lines which are at 18 degree angle. The tip apex in 1.2 um shows a tip half angle of about 10 degrees.