MICROROUGHNESS MEASUREMENTS ON POLISHED SILICON-WAFERS

Six different techniques i.e. Stylus profilometry, Phase Shift Interferometry (PSI), Scanning Optical Microscopy in Differential Phase Contrast mode (SOM-DPC), Light Scattering Topography (LST), Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM) have been used for measurements of silicon surface microroughness. Specimens with 4 different surface roughness levels have been prepared by variation of the mechanical or chemical components of a traditional polishing process. At low microroughness, a contradiction is observed between 2 groups: on one hand stylus and PSI, which sample the longer length scales from about 1 micron upwards, and STM and AFM on the other hand, which in this work sampled in the submicron range. The results of SOM-DPC and LST, which sample intermediate roughness scales, coincide with the latter group.