Enhancement in the Crystalline Quality of Palladium Silicide Films: Multiple Versus Single Deposition
E Mirowski, S R. Leone
Alternate deposition and anneal cycles involving the deposition of 100 of Pd metal and annealing at 350 C are used to grow thick Pd2Si films on Si(111). The surface ordering and bulk crystal properties are compared to films grown by using a single deposition of 200-600 Pd metal followed by annealing at 350 C to give the same nominal PD2Si film thickness. We observe that the surface of the multiple depositon samples remains well ordered after total depositions of 200, 400 and 600 Pd. For the single depositon method, the onset of degradation in surface ordering is observed even at the 200 Pd metal deposition indicating that there are Pd2Si grains (<15 ) present in the upper portion of the film. X-ray diffraction analysis reveals that the bulk structure of the multiple depositon film is single crystal in nature, while the single deposition film has a polycrystalline upper layer. Glancing angle X-ray diffraction data indicate that not only is the polycrystalline portion concentrated at the top of the film, but also the grain size may be smaller near the surface. Growth mechanisms to explain the differences between the multiple and single depositon films are explored.