Interfacial Chemistry of MoS2 Films on Si
Abstract
The adhesion of thin films to their substrates is an important factor in their use in electronics, corrosion prevention, and lubrication. In particular, adhesion may be the critical parameter that determines the wear life of solid lubricant films; it has been suggested that films fail when they are pushed out of the wear track. Systems with chemical bonds across the interface will have enhanced adhesion over systems in which only van der Waals interactions are operative. Covalent materials, such as the important engineering ceramics SiC and Si3N4 and the solid lubricant MoS2, have strong directional bonds. If the same kind of bonds could be formed between such materials, a strongly adhesive lubricant-substrate system should result. The interface between rf-sputter-deposited MoS2 films and single-crystal Si was studied by observing thin (<100 A) films with electron energy loss spectroscopy, Auger electron spectroscopy, and x-ray photoelectron spectroscopy. The interface is not atomically smooth; it is a broad and chemically complex region. The surface of the native oxide (SiO2) is sulfated by the plasma. The initial MoS2 in films deposited at 220 C is chemically the same as crystalline MoS2; that is, there is no chemical bonding between the film and the substrate. There is evidence that the initial MoS2 in films deposited at 70 C is chemically bonded to the crystal, perhaps through Mo-S-O or Mo-O linkages.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 10, 1989
- Accession Number
- ADA216527
Entities
People
- P. A. Bertrand
Organizations
- The Aerospace Corporation