Atomic Structure of the Epitaxial Al/Si Interface

Abstract

AbstractAl was deposited on Si(l l l) and observed by cross-sectional electron microscopy, both in the annealed and as deposited states. It is shown that Al is strongly textured when deposited on Si(111), with Al(111)//Si(111) and AI<110>//Si<110> or AI(100)//Si(111) and AI<I10>//Si<110>. Annealed samples are completely epitaxial with A1(111)//Si(111) and A1<110>//Si<110>. Lattices imaging of the interfaces shows an amorphous layer (native Si oxide) between Al and Si, in the as-deposited case. The two lattices are in contact only at pinholes in the native oxide and fringes on both sides of the interface are seen to be continuous through the interface only at those points. Annealed samples do not show any amorphous or disordered layer at the interface: The two lattices are completely in contact, with lattice fringes extending from one side of the interface to the other. An atomic model of the annealed interface, based on energy considerations and consistent with TEM observations, is proposed.