Transition metal co-precipitation mechanisms in silicon

✍ Scribed by T. Buonassisi; M. Heuer; A.A. Istratov; M.D. Pickett; M.A. Marcus; B. Lai; Z. Cai; S.M. Heald; E.R. Weber

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 994 KB
• Volume: 55
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2007.07.030

✦ Synopsis

Formation mechanisms of precipitates containing multiple-metal species in silicon are elucidated by nano-scale morphology and phase investigations performed by synchrotron-based X-ray microprobe techniques. Precipitates formed at low (655 °C) and high (1200 °C+) temperatures exhibit distinguishing features indicative of unique formation mechanisms. After lower-temperature annealing, co-localized single-metal silicide phases are observed, consistent with classical models predicting that dissolved, supersaturated metal atoms will precipitate into solid second-phase particles. Precise precipitate morphologies are found to depend on the local crystallographic environment. In precipitates formed during slow cooling from higher-temperature anneals, nano-scale phase separation and intermetallic phases are evident, suggestive of a high-temperature transition through a liquid phase. Based on experimental results and phase diagram information, it is proposed that under certain conditions, liquid metal-silicon droplets may form within the silicon matrix, possibly with the potential to getter additional metal atoms via liquid-solid segregation.