Titanium nitride (TiN) has been extensively studied in semiconductor devices because of its ideal thermal, mechanical, and electrical properties, along with its ability to act as a diffusion barrier to WF₆ during W metal fill. Similarly, tantalum nitride (TaN) is being utilized as a diffusion barrier on SiOCH to Cu, as Cu can readily diffuse, causing device reliability issues. Metal halide precursors are typically preferred over organometallic grown films when there is no concern about substrate etching; however, organometallic-grown films usually contain higher levels of carbon and oxygen contamination, which has been correlated with an increase in film resistivity. Plasma enhanced-ALD TiN has been shown to achieve optimal growth rates with lower contamination at temperatures below 350°C, but the film and underlying substrate can suffer from plasma-induced damage. In this study, low temperature thermal ALD TiN_x from anhydrous N₂H₄ and TiCl₄ was performed on SiO₂, and the deposited films were studied using x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). TaN_x films were grown utilizing N₂H₄ and tris(diethylamido)(tertbutylimido) tantalum(V) (TBTDET) and characterized similarly. In situ XPS was employed to demonstrate pulse saturation during ALD for TiCl₄ + N₂H₄ à TiN_x. AFM showed that 40 cycles of TiCl₄ + N₂H₄ at 300°C produces pinhole-free, conformal films. Additionally, the effect of air exposure on TiN_x films was studied; O attacked the TiN_x film, evidenced by observing a 1.5 eV BE shift of the Ti 2p 3/2 peak. A comparison was made of the TiN_x films grown at 300ºC and 400ºC with NH₃ vs. N₂H₄; even at 400ºC there was approximately 2x more O and C and 50% more Cl in NH₃ grown films. Furthermore, N₂H₄ films showed lower resistivities, attributed to lower contamination and likely better nucleation density, especially at 300^oC. In situ XPS was also used to study TaN_x films grown using TBTDET and N₂H₄. To study the nucleation on SiO₂, an initial TBTDET exposure was performed; the Ta 4d peak position confirmed the nucleation and formation of Si-O-Ta bonds. After subsequent cycles, the Ta 4d peak shifts ~2eV toward lower binding energy upon forming Ta-N bonds. While the films were of extremely high purity with stoichiometry resembling Ta₃N₅, the N₂H₄ was unable to reduce the Ta oxidation state from films grown between 100^oC and 300^oC showing the need for some metals for the use of low oxidation state precursors or a stronger, highly energetic reducing agent. These studies with anhydrous N₂H₄ show the potential to form high purity barrier layers using low temperature thermal ALD as long as highly energetic reactants are used.