Electroplated Cu was found to have a fine as-plated microstructure, 0.05 ±0.03 μm, with multiple grains through the film thickness and evidence of twins and dislocations within grains. Over time at room temperature, the grains grew to greater than 1 μm in size. Studied as a function of annealing temperature, the recrystallized grains were shown to be 1.6 ± 1.0 μm in size, columnar and highly twinned. The grain growth was directly related to the time dependent decrease in sheet resistance. The initial grain structure was characterized using scanning transmission electron microscopy (STEM) from a cross-section sample prepared by a novel focused ion beam (FIB) and lift-out technique. The recrystallized grain structures were imaged using FIB secondary electron imaging. From these micrographs, the grain boundary structures were traced, and an image analysis program was used to measure the grain areas. A Gaussian fit of the log-normal distribution of grain areas was used to calculate the mean area and standard deviation. These values were converted to grain size diameters by assuming a circular grain geometry.

was found to be dependent on the electroplating current. It was shown that longer transient times were correlated with a greater incorporation of plating impurities for the bath chemistry used in this study. The present work shows that the grain growth that occurs during the resistance transient is initiated by the formation of abnormally large grains, where the transformed structure reveals strong E3 type twinning. The increase in the fraction of twin grain boundaries with transient time is quantified, and a comparison of the time dependencies of resistivity and the grain size shows that the MayadasShatzkes model can qualitatively describe grain boundary resistivity. X-ray analysis revealed that the structure is strongly { 11 1) textured and the contribution of (200) texture increases during transformation. Atomic Force Microscopy (AFM) and imaging with the secondary electron in-lens detector showed that surface morphology of Cu structures varies across the film and is dependent on the plating current.

No abstract

The formation of thin copper films by H-atom reaction with Cu(FOD)2 and Cu(HFA)2 has been demonstrated at near room temperature. Oxygen atoms have now also been reacted with these β-diketonate copper complexes, producing films of copper oxide which can be readily reduced by subsequent treatment with H-atoms. The thin copper films produced are conductive and highly adherent. The oxygen atom reaction with the copper complex produces a visible chemiluminescent glow, yielding information on the nature of the reaction process.

Figure 1: Diagram of experimental assembly.