A new in-process measurement method for wafer surface roughness

A new in-process optical measurement method is presented for measuring surface roughness of wafer in machining process. The surface quality of wafer, which is the basic material of IC chips, plays an important role in the machining process of IC chips. The arithmetic average height parameter (Ra) is chose to evaluate the surface quality of wafer and an in-process optical measurement is established. A clean fluid beam has been proposed for use to remove the coolants to create an optical measurement region to realize the measurement of the surface roughness, The feasibility of extracting the surface roughness by means of image processing of the spatial distribution of the scattered light intensity is analyzed.