Metrology and analytics for the optimization of CMP processing

The combination of various polishing and machine parameters and their interaction with consumables (e.g. polishing pad, slurry) requires thickens measurements of chemical mechanically polished layers. Spectral reflectometry for thickness measurements of wafers immersed in water has been evaluated and optimized. This measurement technique permits thickness mapping of wafers for in-line applications after polishing and prior to the post-CMP clean. For establishing an efficient cleaning technology, VPD-AAS (vapor phase decomposition - atomic absorption spectrometry) measurements have been performed. The influence on the metallic contamination when adding different chemicals to the DI-water in the brush cleaner after polishing is discussed.