Kinetics of formation of silicides in a-Si:H/Pd interfaces monitored by in situ ellipsometry and kelvin probe techniques

We report the formation of palladium silicides during the exposure of Pd substrates to silane and/or to an rf glow discharge used for a-Si:H deposition. By the use of two in situ techniques (ellipsometry and Kelvin probe) we monitor the kinetics of the reaction of the silane gas and/or of the a-Si:H film with the Pd substrate. The characterization of the samples by Rutherford Backscattering Spectrometry (RBS) allows us to accurately determine the resulting profiles of Pd and silicon. We found that even without plasma Pd₂Si is formed by the exposure of a 500-1500 Å Pd film to the silane at 250°C.