Plasma nitriding of thin molybdenum layers at low temperature

An expanding plasma of pure N-2 gas, (Ar-N-2) and (Ar-N-2-H-2) gas mixtures activated by microwave is used for thermochemical processing of Mo film by nitriding at 400 degrees C. Auger electron spectroscopy (AES) indicates th at (Ar-35% N-2) and (Ar-25% N-2-30% H-2) exposures result in a nitrogen dif fusion greater than after pure N-2 and (Ar-10% N-2) exposures. The (Ar-N-2) plasma removes 50 at.% of oxygen From the surface Mo layers. The addition of H-2 in (Ar-N-2) gas mixture at 400 degrees C and 600 degrees C leads to a large increase of nitrogen diffusion since the nitrogen amount remains co nstant up to a depth of about 50 MI and 200 nm, respectively. This is stron gly correlated to the large decrease of passive oxides and carbides layers of Mo film. The nitrided layers could act as a barrier to diffusion, preven ting Mo film from oxidizing further. (C) 1999 Elsevier Science S.A. All rig hts reserved.