CHEMICAL-MECHANICAL POLISHING FOR SELECTIVE CVD-W

This work investigates chemical mechanical polishing (CMP) for W-fille d contact holes, vias, and trenches by selective chemical vapor deposi tion. A novel process that combines the CMP technique with selective c hemical vapor deposition of tungsten (CVD-W) was employed to remove na il heads due to overgrowth and W-particles on the surface of dielectri c due to selectivity loss. The overfilled nail heads and the selectivi ty loss can be completely removed with very low down-pressure (3 psi) in a very short polishing time (30 s). This indicates that the novel p rocess is very promising for ULSI multilevel interconnection applicati on. The removal rate selectivities of W to thermal oxide, PECVD-TEOS, and BPSG were found to be 47:1, 30:1 and 15:1, respectively, while the selectivities of W to the barrier metals of TiW, Ti and Ta were deter mined to be 0.6:1, 6:1 and 28:1, respectively. (C) 1997 Elsevier Scien ce S.A.