Effect of organic additives on structure, resistivity, and room-temperature recrystallization of electrodeposited copper

Abstract

The effect of 3- N, N-dimethylaminodithiocarbamoyl-1-propanesulphonic acid (DPS) and polyethylene glycol (PEG, MW=8000) on structure, surface roughness, and resistivity of copper electrodeposited from a sulfate–sulfuric acid bath (0.3 M CuSO 4 + 1.8 M H 2SO 4 + 70 ppm Cl −) has been studied by X-ray diffraction (XRD), atomic force microscopy (AFM), and four-point probe measurements. The XRD patterns of 2 μm-thick copper films reveal the presence of (1 1 1), (2 0 0), (2 2 0), (3 1 1), and (2 2 2) peaks, intensity of which is dependent on the concentration of the organic additives in the plating bath. We show that addition of the above-mentioned organic additives affects the roughness of the film surface. Room-temperature recrystallization occurs in the films over the time period of several weeks if they are electodeposited with both DPS and PEG additives present in the plating bath. It is accompanied by a change in stress, from compressive to slightly tensile, and a decrease in resistivity. The role of stress-relieving recrystallization is linked to the increase in grain size and enhancement in (1 1 1) and especially (2 0 0) texture.