A profilometer is an instrument used to measure the height profile of a surface in order to quantify its roughness or shape. Typically profilometers are used for checking the heights of structures such as steps, ridges, or trenches formed on the wafer during processing. The achievable vertical resolution is in the nanometer level, though lateral resolution tends to be poorer. There are two main types of profilometers: contact and optical (non-contact).
In a contact profilometer a sharp stylus is pressed vertically against the sample surface with a controlled force and moved laterally across the sample. Both the vertical and lateral positions of the stylus are recorded during the scan, producing a graph ...