Phase Growth in Amorphous Si-Cu and Si-Co Systems: Combination of SNMS, XPS, XRD, and APT Techniques

Abstract

Abstract. It is shown, by the combination of SNMS, (Secondary Neutral Mass Spectrometry), XRD, XPS and APT (Atom Probe Technique) that the growth of the Cu3Si crystalline layer at 408 K between the amorphous Si and nanocrystalline Cu thin films follows a linear law and the shifts of the Cu3Si/Cu and Cu3Si/a-Si interfaces approximately equally contributed to the growth of this phase. It is also illustrated that the Si atoms diffuse fast into the grain boundaries of the nanocrystalline Cu, leading to Si segregation. Both the SNMS and APT results indicate that even during the deposition of Cu on the amorphous Si an intermixed region is formed at the interface. This region easily transforms into a homogeneous Cu3Si crystalline reaction layer subsequently which further grows following apparently an interface controlled linear kinetics. Similar experiments performed in Co/a-Si system to study the formation and growth kinetics of the intermetallic phase. However, interestingly, homogenous formation of the new phase at the Co/a-Si interface was not always observed.