Morphology of Nanometer‐Thick Electrolytic Copper Layers Investigated by Atomic Force Microscopy

Abstract

The effect of electrolytic deposition parameters on the morphology of very thin (5 nm) copper layers was investigated by atomic force microscopy. Such thin copper layers were electrodeposited from solutions with different concentrations of copper sulfate and sulfuric acid on silicon wafers sputter-coated with a Ti layer and a Cu top layer. The characterization of these layers by atomic force microscopy shows that 5 nm thick Cu layers deposited by galvanostatic electrodeposition are homogeneous and present granular features on the surface. An increase of the copper sulfate concentration results in an increase in the size of the granular surface features. The lowest surface roughness is observed at a concentration of 100 g/L sulfuric acid.

Size effects in electrochemistry

“…The techniques of atomic-force microscopy in a noncontact mode progressively gain importance. 32,134 The advantage of such methods is the possibility of studying objects of low conductivities, for example, in electroplating on wide-band semiconductors, 31,32 in structural transformations of polymer deposits during dedoping 135 and in the course of formation of nanosize barrier oxide layers. 136 Combined photo-assisted probe techniques are being actively developed.…”

“…The existing nanotechnologies can be classified as local 31 and non-local. 19,160 Most often, the latter represent different versions of lithographic techniques, i.e., multistage combined technologies using photoinduced processes.…”

Investigations of X-ray metallic capillaries

“…Similarly, the increase in the roughness size beyond level of 1 nm (which equals several atomic diameters) marks significant drop in the gain parameter but still the level of 3 nm can be acceptable. Some authors reported methods resulting in the electroplated copper layer with very low rms parameter, about 1-2 nm [47][48][49]. Also, an increase in energy of the transmitted photons gives a strong attenuating effect; it seems from our simulations that the optimal energies of the transmitted photons should be in a range below 8 keV.…”

Growth Mode of Copper Films Electrodeposited on Silicon from Sulfate and Pyrophosphate Solutions

“…In Table I, the roughness of the 100 nm copper deposits and the corresponding substrates are reported. Comparison between the copper sulfate solution 23 and the copper pyrophosphate solution shows that the last solution gives smoother copper films. It appears that in our experiments the film roughness is to a small extent related to the initial roughness of the substrate but is more related to the roughness due to the growth mode.…”