Reduction of Particle Contamination in Plasma-Etching Equipment by Dehydration of Chamber Wall

The mechanism of particle generation is investigated in order to prevent defects formed on wafers in the plasma etching of multi-layered films composed of tungsten silicide (WSi) and polycrystalline silicon (poly-Si). Particles are measured by an in situ monitoring system using laser light scattering during the etching process. The particles are composed of AlF 3 , which is presumably generated by reacting the coating material Al 2 O 3 on the etching chamber wall with plasma containing fluorine atoms, F in the presence of H 2 O absorbed into the chamber parts and materials. We demonstrated successfully that dehydration of the chamber parts and materials by plasma discharge suppresses particle generation.