Aluminum films deposited at three different conditions, such that texture is the only microstructural variable, were tested for electromigration behavior. Texture analysis shows that random and (111) fiber texture components are present in the films deposited by both partially ionized beam (PIB), physical vapor deposition and sputtering. Two parameters are required to properly quantify the texture: (111) volume fraction and the distribution (half-width) of the (111) fiber component. As the (111) texture becomes stronger, the median time to failure increases, while the failure standard deviation decreases. Previous texture correlations are based on incomplete information, so they cannot predict electromigration behavior in all cases.

The effects of thin Ti, TiN, or Ti/TiN underlayers on the development of the crystallographic texture and the grain structure are explored. Metal layers ∼0.5 μm in thickness of Al-0.5Cu or of Cu are deposited on these underlayers and on amorphous SiO2 as a reference. A strongly textured underlayer such as Ti〈0002〉 or Ti〈0002〉/TiN〈111〉 induces a similarly strong 〈111〉 texture in the AlCu. In copper with 〈111〉, 〈200〉, and random texture components, an underlayer induces a stronger 〈111〉 component compared to an analogous film deposited on SiO2. A nearly random texture in TiN significantly weakens the texture in subsequent metal films. Grain size distributions in all AlCu films are monomodal reflecting a process of normal grain growth. The grain size distribution for Cu sometimes deviates from lognormal. The bimodal distribution implies that grain growth is abnormal even though the median grain size does not exceed a low multiple of the film thickness.

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The addition of 0.4–8.6 at. % Co to Cu thin films strongly influences the temperature evolution of microstructure, stress, and resistivity. For concentrations near 1 at. % Co in coevaporated Cu-Co on oxidized Si, normal grain growth begins at about 75 °C, about 50 °C lower than in pure Cu. There is an abrupt decrease in resistivity and stress at a temperature which increases with Co content from 120 °C (0% Co) to 250 °C (8.6 at. % Co), and coincides with precipitation of Co within Cu grains. A dramatic change in texture is observed in both coevaporated and electroplated Cu-Co films upon annealing above 250 °C. As-deposited films have a three-component texture of (111) fiber, (200) fiber, and random but annealed films have a dominant (200) fiber texture. This ‘‘cube’’ texture differs from the dominant (111) texture of annealed pure Cu, and appears to be coupled to an abnormal grain growth process since many grains are observed to be larger than ten times the film thickness. It is proposed that segregation of Co to external surfaces or to Cu grain boundaries may favor this (200) texture by selectively affecting grain-boundary mobility or the surface energy driven grain growth.