Plasma-assisted atomic layer deposition ͑ALD͒ of Cu, via Cu II (tmhd) 2 (tmhd ϭ tetramethyl-3,5-heptanedionate) and an inductively coupled hydrogen plasma, is shown on metallic and dielectric surfaces. Nonselective deposition was achieved on SiO 2 , Au, and TaN x in a temperature range between 60 and 400°C. Deposition was self-limiting from ϳ90 to 250°C. A novel method to determine self-limiting behavior of the first half-reaction is presented; it is determined by pulsing the precursor once, for a long time, and the resulting growth is measured by Rutherford backscattering spectrometry. Further, saturation curves for plasmaassisted ALD of each half-reaction and as a function of purging time were also determined. In contrast, thermal ALD via Cu II (tmhd) 2 and H 2 was attempted and was very slow within the self-limiting temperature range. These experiments were undertaken on all the metallic and dielectric surfaces studied here including a plasma-assisted atomic layer deposited Cu seed.Cu has been accepted as the primary interconnect material for high-performance integrated circuits ͑ICs͒. To extend Cu for future gigascale IC applications, research continues on depositing conformal, uniform, and continuous Cu films into high aspect ratio features. 1 In the near future, the commonly accepted route for Cu deposition is intended to be ''long throw'' physical vapor deposition ͑PVD͒ such as an ionized metal PVD seed, followed by electrochemical deposition for trench/via fill. 2 If such an approach cannot be extended, there is a need to investigate alternative deposition processes. One promising method is to replace the PVD seed layer with atomic layer deposition ͑ALD͒. ALD is defined by the use of self-limiting chemical reactions to obtain layer-by-layer growth. 3 Typically, a metal ALD cycle is composed of four parts: (i) the first reactant or precursor is dosed on the substrate, followed by (ii) inert gas purging to remove excess precursor, (iii) a second reactant is delivered to the substrate to remove organic or inorganic ligands and reduce the metal to its elemental state, and finally (iv) an inert gas purging is performed to remove the excess second reactant. Steps (ii) and (iv) are necessary so that intermixing of the reactants does not take place resulting in parasitic chemical vapor deposition ͑CVD͒. The repetition of this procedure yields precise thickness control and conformal thin films. Many attempts at Cu ALD have been published including those on CuCl/Zn, 4 CuCl/H 2 , 5 selective Cu II (tmhd) 2 /H 2 (tmhd ϭ tetramethyl-3,5-heptanedionate) on noble metals, 6 the formation of a Cu oxide intermediate by Cu II (hfac) 2 (hfac ϭ 1,1,1,5,5,5-hexafluoroacetylacetonate) and H 2 O followed by reduction at each cycle, 7,8 Cu II (acetylacetone) 2 /H 2 , 9 and ALD using a Cu͑I͒acetamidinate compound with H 2 . 10 All the aforementioned works showed either some sort of selectivity or lack of self-limiting behavior. In particular for the Cu II (tmhd) 2 /H 2 process, a noble metal seed layer was necessary 11 but not rep...