Effect of Mn Alloying on the Internal and Surface Structure of Cu Thin Films Designed for Interconnect Applications

Internal and surface structure of Cu - Mn alloys as prospective contact and interconnect material for memory and IC applications were studied. A combinatorial preparation was used as a quick method to overview the characteristics as a function of composition of the DC sputtered Cu - Mn thin films. At low Mn content the alloys exhibit fcc - Cu(Mn) solid solution phas e, around 50 at% Mn content an amorphous phase , while at high Mn content an  Mn(Cu) solid solution phase . The three single - phase regions are separated by two two - phase regions composed of crystalline and amorphous phase s . The dependences of the grain size and surface roughness on film composition show s imilar, parabol ic behaviour . The grain size distributions obtained from AFM and TEM images show good correlation, although differe nt from th ose obtained by the Scherrer formula around 25 at % Mn content . From the difference spontaneous phase separation process could be concluded at this composition.