TEM observation of the microstructure in sputtered NiFe/Au multilayer films

Abstract

The cross-sectional nanostructure and plan-view structure of NiFe/Au multilayer films (MLFs) were investigated using high-resolution electron microscopy (HREM). MLF series with different Au layer thicknesses, unseeded or with Cr or Cu buffer layers, were deposited on Si (100) wafers by magnetron sputtering. The HREM images show that the Au layers have a strong (111) texture along the film normal direction and dominate the crystallographic growth of the MLFs. Although the layer structure looks wavy near the grain boundaries, the interfaces between the Au and NiFe layers are very flat - some atomic steps and twins are visible. The difference in lattice parameters between the NiFe and Au is taken up by misfit dislocations at the interfaces. Plan-view images show the fcc (111) lattice planes of NiFe and Au lying in the plane of the layers. Thin buffer layers of Cr and Cu do not affect the crystal growth, but a thick Cu buffer (15 nm) disorders the (111) texture and the interface structure of the MLFs.