Grooves play a key role in CMP slurry fluid mechanics, heat and polish debris removal, and mixing of fresh and spent chemistries. An experiment was developed using porous-media fluid mechanics to quantify the fluid flow resistance in the pad asperity layer relative to the grooves. New pad descriptors were obtained with which a 3-D fluid flow model was built of the full pad-wafer gap of a dual-axis polisher. Slurry motion was studied in concentric circular, XY grid, and radial grooves relative to adjacent texture areas and found in all cases to depart strongly from the direction of platen rotation. Resolved at groove scale, transient slurry mixing profiles in the pad-warbr^ap showed trailing wakes in the grooves having a length dependent- on the local orientation of the pad and wafer velocity vectors. Circular grooves created steady-state mixing patterns under the wafer, whereas XY and radial grooves induced cyclic mixing dynamics.
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