Figure 4. Mechanism studies in Ag-Al-Si layers.

Evaporation of Al and Ag thin layers on the Si substrate. (a) Bright field TEM image showing Ag and Al layers deposited on the Si wafer; (b), (d), (f), (h) Dark field TEM images showing the deposited layer on the Si wafer before heat treatment and after heating up to 573, 673 and 873 K, respectively; (c), (e), (g), (i) EDS line profiles across the deposited layer before heat treatment and after heating up to 573, 673 and 873 K, respectively. (d–e) Interdiffusion of Al and Ag at the interface forms an Al-Ag solid solution layer at 573 K. (h–i) The oxidation of Al occurs by the redox reaction of 4/3Al + SiO₂ → 2/3Al₂O₃ + Si at the interface between the Al-Ag solid solution layer and the Si wafer.