SERDAR AKSU: CHEMICAL MECHANICAL PLANARIZATION (CMP)
The increasing complexity of device designs and the emergence of submicron device geometries both rely on minimum surface topographies on the silicon wafers during processing. Chemical mechanical planarization (CMP) is the preferred method to provide global and local planarization. It has become the process of choice for multilevel metallization process flows, as it meets the stringent lithographic requirements of device manufacturing on silicon wafers.
SLURRY •Abrasive particles •Chemicals Wafer Slurry feeder Polishing Plate POLISHING PAD Pressure Rotation
Carrier
CMP is a chemically active
polishing process, which enables
manufacture of chips with multilevel metallization in planar manner
CMP takes advantages of the synergetic effect of both mechanical and chemical forces for planarization of wafers. During CMP, the wafer is rotated and pressed against a rotating platen covered by a polishing pad. Chemically active slurries are applied. At present slurries contain sub-micron sized abrasive particles (SiO2, Al2O3, ceria, diamond, etc.), but alternative approaches such as abrasives fixed in the pad matrix are under development in the industry. Both the mechanical action of the abrasive particles and the chemical action of slurry constituents remove material from the wafer surface. Planarization results because material is removed faster from protruding regions on the surface than from recessed regions.
Here are some useful links if you would like to learn more about CMP:
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You can reach me at: serdar@socrates.berkeley.edu |