Characterization of ion-beam-sputtered tungsten films on silicon

• Published in: Applied surface science Vol. 36; no. 1; pp. 231 - 239
• Main Authors: Meyer, Françoise, Schwebel, Christian, Pellet, Claude, Gautherin, Guy
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 1989; Elsevier Science
• Subjects: Analysing. Testing. Standards; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Measurement of properties and materials state; Metals, semimetals and alloys; Metals. Metallurgy; Nondestructive testing; Physical properties of thin films, nonelectronic; Physics; Specific materials; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Scanning electron microscopy; Electrical conductivity; Silicides; Support; Temperature effect; Ion beam; Transition metal; Experimental study; Physical properties; Texture; Sputtering; Thin film; Textures; Process conditions; Substrate; Rutherford backscattering; Reflection high energy electron diffraction; RHEED diffraction; Electric resistivity; Silicon; Microstructure; Auger electron spectrometry
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/0169-4332(89)90918-5

The present work reports a study of the dependence of the properties of ion-beam-sputtered tungsten on silicon upon deposition parameters, especially deposition temperature and nature of the working gas. The physical characteristics of W layers such as morphology (SEM), texture (RHEED) and resistivity were investigated. The thermal stability and the silicide formation were studied by means of in situ AES and ex situ RBS. When W was deposited on heated substrates, the metal could react and disilicide (WSi 2) could form at temperature as low as 450°C. The nature of the rare gas had a great influence on layer properties: roughness, density, room temperature resistivity, resistivity dependence on layer thickness and measurement temperature. Resistivities of layers grown with xenon exhibited rather normal behaviour, i.e. characteristic of electron-phonon scattering, whereas layers obtained with argon gave rise to abnormal results that revealed that these layers had a great defect concentration and were polluted with a rather large amount of argon. This rare gas contamination was independent of the deposition temperature. We believe that energetic particles, bombarding the deposit as it accumulates, produce defects in the W layer and induces the abnormal properties of the metal layers. These particles are generated by reflection of the primary ions on the target, and they are expected to be more numerous when the working gas is argon according to its very low atomic mass relative to tungsten.