We report the electrical resistance and microstructure of sputter deposited copper thin films grown in an oxygen containing ion-beam sputtering atmosphere. For films thinner than 5 nm, 2-10% oxygen causes a decrease in film resistance, while for thicker films there is a monotonic increase in resistivity. X-ray reflectivity measurements show significantly smoother films for these oxygen flow rates. X-ray diffraction shows that the oxygen doping causes a refinement of the copper grain size and the formation of cuprous oxide. We suggest that the formation of cuprous oxide limits copper grain growth, which causes smoother interfaces, and thus reduces resistivity by increasing specular scattering of electrons at interfaces.

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We report and contrast both the electrical resistance and the microstructure of copper thin films deposited in an oxygen containing atmosphere by ion-beam and dcmagnetron sputtering. For films with thicknesses 5 nm or less, the resistivity of the Cu films is minimized at oxygen concentrations ranging from 0.2% to 1% for dc-magnetron sputtering and 6% to 10% for ion beam sputtering. Films sputtered under both conditions show a similar decrease of interface roughness with increasing oxygen concentration, although the magnetron deposited films are smoother. The dc-magnetron produced films have higher resistivity, have smaller Cu grains, and contain a higher concentration of cuprous oxide particles. We discuss the mechanisms leading to the grain refinement and the consequent reduced resistivity in both types of films.

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Surface particle defects smaller than the minimum detection limit (MDL) of particle detection metrology, may, after a thin-film deposition step, get decorated and become larger than the MDL. Chip manufacturers may therefore incorrectly identify the thin-film deposition step as the defect creation step and allocate resources incorrectly. The effect of thin film deposition on pre-existing poly-styrene latex (PSL) spheres on the wafer surface was studied. Results show that both the physical size and scattering cross section of the spheres increased after thin film deposition. For a film thickness of 128 nm, the increase in size of the PSL spheres was found to be about 60-80 nm depending on original particle size. Experimental results are in good agreement with feature scale simulations. Shadowing at the interface of large PSL spheres and the wafer surface was predicted by simulations and confirmed by experimental observations.