Surface qualities after chemical–mechanical polishing on thin films

Demands for substrate and film surface planarizations significantly increase as the feature sizes of Integrated Circuit (IC) components continue to shrink. Chemical Mechanical Polishing (CMP), incorporating chemical and mechanical interactions to planarize chemically modified surface layers, has been one of the major manufacturing processes to provide global and local surface planarizations in IC fabrications. Not only is the material removal rate a concern, the qualities of the CMP produced surface are critical as well, such as surface finish, defects and surface stresses. This paper is to examine the CMP produced surface roughness on tungsten or W thin films based on the CMP process conditions. The W thin films with thickness below 1000 nm on silicon wafer were chemical–mechanical polished at different down pressures and platen speeds to produce different surface roughness. The surface roughness measurements were performed by an atomic force microscope (DI D3100). Results show that the quality of surface finish (Ra value) is determined by the combined effects of down pressures and platen speeds. An optimal polishing condition is, then, possible for selecting the down pressures and platen speeds.