Eutectic reaction of gold thin-films deposited on silicon surface

Eutectic reaction of gold thin-films deposited on silicon surfaces have been studied using a field-ion microscope (FIM) and a time-of-flight atom probe FIM. The heat treatment for the eutectic reaction was performed at about 400–1000 °C for a few seconds. Amount of 0.7–100 Au monolayers were deposited on a Si tip surface, and Au rods embedded in the Si substrate are formed in eutectic alloys near the surface after heating. The size of the Au rods in these eutectic alloys is proportional to the amount of deposited Au, while the number of rods increases with decreasing amount of deposited Au. These eutectic alloys are always covered by an intermixed layer. No crystalline silicide phases were observed. The atom probe analysis showed that the grown Au rods contain no Si atoms. On the other hand, it showed that the Si phase contains a very small amount of Au atoms.