Abstract
Solid phase reactions in Fe thin films on epi-Si 0.8 Ge 0.2 , poly-Si 0.7 Ge 0.3 , a-Si 0.8 Ge 0.2 , and a-Si 0.7 Ge 0.3 layers on silicon have been investigated. The as-deposited samples were in situ annealed in the ultrahigh vacuum chamber at 400-800°C for 30 min. The island structure was found to cause the abrupt increase in the sheet resistance of the annealed Fe/SiGe samples at 700-800°C. The formation of FeSi islands containing a small amount of Ge is attributed to the preferential reactions of Fe with Si to Ge. As the annealing temperature was raised to 800°C, the Fe(Si 1-x Ge x ) phase is the only phase found in the annealed Fe/epi-Si 0.8 Ge 0.2 and Fe/poly-Si 0.7 Ge 0.3 samples. On the other hand, at the annealing temperature above 700°C, the β-Fe(Si 1-x Ge x ) 2 phase was observed in the annealed Fe/a-Si 0.8 Ge 0.2 and Fe/a-Si 0.7 Ge 0.3 but the Fe(Si 1-x Ge x ) is still the dominant phase. The results indicate that the formation of Fe disilicide was retarded by the presence of Ge atoms. © 2004 Elsevier B.V. All rights reserved.