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Dual Emission Laser Induced Fluorescence (DELIF) is employed to attempt to experimentally determine the nature of the lubrication regime in Chemical Mechanical Planarization. Our DELIF setup provides images of the polishing slurry between the wafer and pad. Static images were taken to provide a baseline, then dynamic runs were conducted. Analyzing these images shows that the wafer only contacts the pad in a small number of places around the wafer, mainly due to the pad's topography.

Recent experimental advances using dual emission laser induced fluorescence and image processing have provided high spatial and temporal resolution maps of the slurry layer during chemical mechanical polishing ͑CMP͒. Intensity differences in the images correspond to fluid layer thickness variations as the slurry passes between different pad and wafer topographies. Asperities expand under 14 µm deep wells and are compressed beyond the trailing edge of the well. Air pockets travel from the leading to the trailing edge of the wafer through 27 µm deep wells. The pads tested were Freudenberg FX9, Rodel IC1000, and experimental pads from Cabot Microelectronics.

Duel Emission Laser Induced Fluorescence (DELIF) and friction measurements are taken in-situ during CMP to observe slurry flow beneath a model of an integrated circuit (IC) wafer. Friction measurements average around 7.5 lb and multiple frequencies are observed. Slurry film thicknesses on the order of a 10±3µm were observed during CMP of a flat wafer. The film thickness seems uncorrelated to friction measurements except when the pad and wafer rotation speeds are significantly slowed. DELIF has also accurately measured a 9µm etched step, with noise in the image equal to ±3 µm.