Roughness evolution of Nb films with thickness

摘要

The morphology of Nb films with thickness ranging between 10 and 1000 nm deposited by rf sputtering and the electron cyclotron resonance (ECR) technique was investigated by scanning probe microscopy (SPM). The roughness of the films increases with increasing thickness following a power law with an exponent of 0.26 and 0.6 for conventional sputtering and the ECR technique respectively. Firm surface features evaluated by the autocorrelation function of the SPM images show a similar dependence on the thickness with an exponent of 0.25 independent of the deposition system. Evolution of Nb film morphology deposited by rf sputtering is compatible with a surface diffusion-driven growth process where desorption is negligible, while films deposited by the ECR technique show a more complex behaviour. [References: 21]