Average stress evolution as a function of film thickness for two electrodeposition processes of Cu on glass/Au substrates with the same average current density: pulse electrodeposition with pulse current, 5 ms pulse-on time and 50 ms pulse-off time (solid line), and dc electrodeposition with current density (dashed line). The pulsed deposit was stopped at a thickness of 500 nm.
The evolution of (a) deposit stress thickness and (b) average film stress as a function of pulse deposition time. The deposition potential was −0.70 V vs Cu with 0.1 s pulse-on time and 9.9 s pulse-off time.
The evolution of (a) deposit stress thickness as a function of time and (b) average film stress as a function of deposit thickness for pulse-on times of 0.1 and 0.5 s.
(a) TEM Bright field image of Cu grains containing nanoscale twin boundaries from the sample deposited during in situ stress measurements (−0.70 V pulse potential, 0.1 s pulse-on time, and 9.9 s pulse-off time), diffraction patterns of the Cu grains showing twinning spots. The growth direction and the top of the Cu film are indicated with arrows. (b) Histogram of twin spacing for the Cu film sample deposited during in situ stress measurements.
Total energy of FCC Cu and nanotwinned Cu as a function of strain. The total energies of nanotwinned Cu with 6 (111) layers, 9 (111) layers, and 12 (111) layers at strain-free states are indicated in the figure. The dashed lines show that if 0.2% tensile strain in FCC Cu is fully relieved, the possible nanotwin structure with the same energy will be the spot which is marked as layer spacing. The spacing can be calculated as 135 (111) layers, which is about 28 nm.
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