Dominant role of grain boundary scattering in the resistivity of nanometric Cu films

The dominant role of grain boundary scattering in the low-temperature resistivity of both ${\text{SiO}}_2$ and $\text{Ta}/{\text{SiO}}_2$ encapsulated Cu thin films is demonstrated by the experimental variation and quantification of film thickness, roughness, and grain size. The independent variation in film thickness (28–158 nm) and grain size (35–466 nm) is achieved through subambient temperature film deposition followed by annealing. Experimentally measured film resistivities are compared with both surface scattering and grain boundary scattering models for the classical size effect, showing the dominance of the latter.

Figure 1

Plot of grain sizes of Cu thin films as a function of Cu layer thickness. The open circles show an example of an ideal data set without correlation between the two variables and the filled circles are the experimental data from Table .

Figure 2

The resistivity of ${\text{SiO}}_2/\text{Cu}/{\text{SiO}}_2$ and ${\text{SiO}}_2/\text{Ta}/\text{Cu}/\text{Ta}/{\text{SiO}}_2$ thin films (a) as a function of Cu layer thickness and (b) as a function of Cu layer grain size. The data points correspond to the samples listed in Table . The solid curve corresponds to the FS model in (a) and MS model in (b).