The thermal atomic layer deposition (ALD) of copper oxide films from the nonfluorinated yet liquid precursor bis(tri-n-butylphosphane)copper(I)acetylacetonate, [((Bu3P)-Bu-n)(2)Cu(acac)], and wet O-2 on Ta, TaN, Ru, and SiO2 substrates at temperatures of < 160 degrees C is reported. Typical temperature-independent growth was observed at least up to 125 degrees C with a growth-per-cycle of similar to 0.1 A for the metallic substrates and an ALD window extending down to 100 degrees C for Ru. On SiO2 and TaN, the ALD window was observed between 110 and 125 degrees C, with saturated growth shown on TaN still at 135 degrees C. Precursor self-decomposition in a chemical vapor deposition mode led to bimodal growth on Ta, resulting in the parallel formation of continuous films and isolated clusters. This effect was not observed on TaN up to similar to 130 degrees C and neither on Ru or SiO2 for any processing temperature. The degree of nitridation of the tantalum nitride underlayers considerably influenced the film growth. With excellent adhesion of the ALD films on all substrates studied, the results are a promising basis for Cu seed layer ALD applicable to electrochemical Cu metallization in interconnects of ultralarge-scale integrated circuits.