A quantitative analysis of room temperature recrystallization kinetics in electroplated copper films using high resolution x-ray diffraction

Abstract

Time-resolved in situ x-ray diffraction measurements were used to study the room-temperature recrystallization kinetics of electroplated copper thin films with thicknesses between 400 and 1000 nm. The thinnest films exhibited limited recrystallization and subsequent growth of grains, while recrystallized grains in the thicker films grew until all as-plated microstructure was consumed. For all films, recrystallized grains that belonged to the majority texture component, ⟨111⟩, started growing after the shortest incubation time. These grains exhibited volumetric growth until they achieved the film thickness. After this point the growth mode became planar, with the ⟨111⟩-type grains growing in the plane of the film. Grains with the ⟨100⟩ direction normal to the film surface started growing after the ⟨111⟩-type grains switched to planar growth. However, the planar growth of this texture component finished at the same time as the growth of the ⟨111⟩ grains. Profile fitting of the 111 peak permitted the separation of the diffraction signals from recrystallized and as-plated grain populations. The average strains in these two populations, calculated from the peak position of the corresponding {111} reflections, were different, indicating a heterogeneous stress state within this texture component. The increasing volume fraction of recrystallized ⟨111⟩ grains with time was monitored via the variation in the diffracted intensity. This variation could be represented by the Johnson–Mehl–Avrami–Kolmogorov model.