Enhancement in the crystalline quality of palladium silicide films: multiple versus single deposition

Alternate deposition and anneal cycles involving the deposition of 100 Angs trom of Pd metal and annealing at 350 degreesC are used to grow thick Pd2Si films on Si(1 1 1). The surface ordering and bulk crystal properties are c ompared to films grown by using a single deposition of 200-600 Angstrom Pd metal followed by annealing at 350 degreesC to give the same nominal Pd2Si film thickness. We observe that the surface of the multiple deposition samp les remains well ordered after total depositions of 100, 400 and 600 Angstr om Pd. For the single deposition method, the onset of degradation in surfac e ordering is observed even at the 200 Angstrom Pd metal deposition indicat ing that there are Pd2Si grains ((15 A) present in the upper portion of the film. X-ray diffraction analysis reveals that the bulk structure of the mu ltiple deposition film is single crystal in nature, while the single deposi tion film has a polycrystalline upper layer. Glancing angle X-ray diffracti on 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 sur face. Growth mechanisms to explain the differences between the multiple and single deposition films are explored. (C) 2000 Elsevier Science B.V. All r ights reserved.