Description of the CMP Process

FIGURE 3.3 Schematic of a typical orbital chemical-mechanical planarization tool (from Ref. 2). 

Chemical-mechanical planarization occurs when the surface of the wafer to be polished is forced against a polishing pad. Aqueous slurry that contains abrasive particles is placed on a polishing pad. The wafer is moved relative to the slurry-covered pad and the rate at which material is removed is often described by the heuristic equation called Preston s law  

Machine parameters Downpressure, linear velocity, and slurry flow 

Particle characteristics Size, size distribution, shape, mechanical properties, surface chemistry, dispersion stability, concentration, agglomeration, and oversize particle count 

Slurry chemistry Oxidizers, pH and pH drifts, pH stabilizers, complexing agents, dispersants, and corrosion inhibitors 

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