Analysis of Pad Surface Roughness on Copper Chemical Mechanical Planarization

For Cu high removal rate (RR) chemical mechanical planarization (CMP), the effect of pad surface roughness on Cu RR was investigated. Because surface roughness measured by the stylus profiler and the laser microscope (optical) profiler includes various topographies, it is difficult to conclude which effective roughness parameter affects Cu RR. Accordingly, the measured surface roughness was classified into two types of roughness scales. One is the topography by pores, and the other one is the micro roughness caused by conditioner. These were divided by a wavelength of surface profile. In this result, a stylus profile could not precisely trace two types of roughness scales. On the other hand, an optical magnification of 400 could trace the change in topography by micropores. And an optical magnification of 1000 could trace the change in micro roughness caused by conditioning. In the evaluation of Cu RR and the classified roughness, micro roughness measured by the optical magnification of 1000 was strongly correlated with Cu RR. It is concluded that Cu RR is affected by micro roughness caused by conditioner, and also its roughness is necessary to be measured by an optical profiler at high magnification.