Orientation dependence of the Cu-Ni and Cu-Fe reactions using Cu(100) and (111)

Abstract

Epitaxially deposited Cu(100) films on Si(100) substrates have been used to grow a number of metals with the same orientation, including Ni, Co, Ir, Rh, and Pd, achieving metal-metal epitaxy on silicon (MMES) near room temperature. Other metals, which do not grow epitaxially on Cu, show an epitaxial growth when another metal epitaxially deposited on Cu is used as seed. Fe, a body-centered cubic metal, shows only the (110) orientation when deposited directly on both Cu(100) and (111). The Cu-Ni and Cu-Fe reactions, however, show the same dependence on the Cu orientation. Both the Ni(100)/Cu(100)/Si(100) and Fe(110)/Cu(100)/Si(100) structures show a less outdiffusion of Cu through the Ni and Fe films than the respective Ni(111)/Cu(111)/Si(111) and Fe(110)/Cu(111)/Si(111) structures. The orientation dependence is similar to that of the outdiffusion of Cu through gold using oriented Cu, with Au in an (111) orientation on both Cu(100) and (111). The orientation dependence of the Cu-Ni and Cu-Fe reactions is explained using the interface bonding models, where the face-centered cubic structure of Cu is shown to favor the reaction for the (111) orientation over that for the (100) one. © 1990.