The plasma-enhanced atomic layer deposition ͑PEALD͒ of tantalum nitrides ͑TaN͒ thin films has been performed using terbutylimidotris͑diethylamido͒tantalum and hydrogen radicals at a temperature of 260°C. The film thickness per cycle is also self-limited at 0.8 Å/cycle, which is thinner than that of the conventional atomic layer deposition ͑ALD͒, 1.1 Å/cycle. X-ray diffraction analysis indicates that the as-deposited films are not amorphous but polycrystalline mixed with cubic TaN and TaC. The film crystallinity as well as the film density increases with the pulse time and the electrical power of the hydrogen plasma used. By using the hydrogen radical as a reducing agent instead of NH 3 , which is a typical reactant gas used in ALDs and metallorganic chemical vapor depositions of TaN, the films show a much lower electrical resistivity and show no aging effects under exposure to air, owing to the increased film density and crystallinity, and the presence of TaC bonding. In addition, it has been shown that films, which are formed by the PEALD, retain perfect step coverage on the submicrometer holes with an aspect ratio of 10:1.As increasing demand for smaller, faster electronic devices in ultralarge scale integrated devices ͑ULSI͒, copper ͑Cu͒ with a lower resistivity and an enhanced electromigration resistance represents a promising material for providing better performance as an interconnect metal than aluminum ͑Al͒ alloys which are currently in use. 1 However, Cu forms Cu-Si compounds and an easily drift through the oxide at a low temperature. 2 Therefore, a diffusion barrier between Cu and its underlying layers is thought to be a prerequisite for Cu to be used in applications for silicon integrated circuits. For this purpose, transition metal nitrides represent attractive alternatives for use in Cu diffusion barriers. Among these, tantalum nitride has received the most interest because of its high thermal stability and resistance to forming compounds with copper. 3,4 Until now, TaN films have been formed using a collimated and ionized physical vapor deposition ͑PVD͒ technique, since the aspect ratio of contact and via holes continuously increases, this technique will eventually meet application limits in forming conformal TaN films on the holes due to its line-of-sight type approach. In order to overcome this technological barrier, metallorganic chemical vapor deposition ͑MOCVD͒ of TaN films has been studied over the past 10 years, but conformal deposition without generating particles and an improvement in electrical resistivity remain primary issues. 5 In this respect, atomic layer deposition ͑ALD͒ represents an attractive candidate for forming TaN thin films on contact and via holes, because of its inherent abilities to grow conformal thin films almost perfectly and to prevent particle generation caused by intermixing between the reactant gases used, and to control the film thickness digitally on an atomic scale. [6][7][8] In practice, the upper deposition temperature in ALD is determined from the self-decompo...