Research on new technology of surface roughness measurement

A method to detect surface roughness by reflected interference pattern of transparent (or semitransparent) film is introduced, whose thickness testing range is from 0.2 micron to less than 20 micron. In the testing for silicon dioxide film, the thickness testing error is within 2 nm compared with the results obtained from ellipsometry. Moving on a film, an optical fiber sensor can be used to get the thickness value of different points on the film surface by analyzing the reflected interference pattern. With the help of step motor, the film surface roughness is detected through continuous measurement to the thickness of different points on the film. This technique has the advantages over the other non-contact detecting ones due to it has no limit on transverse testing range and its quite simple system.