ANALYSIS OF THE OXIDATION-KINETICS AND BARRIER LAYER PROPERTIES OF ZRN AND PT RU THIN-FILMS FOR DRAM APPLICATIONS/

ZrN and Pt/Ru thin films have been grown by an automated ion beam sput ter-deposition system. Both materials were evaluated for use as barrie r layers (ZrN) and bottom electrodes (Pt/Ru) in dynamic random access memory (DRAM) applications. The ZrN films had resistivities on the ord er of 250-300 mu Omega cm. The ZrN films were (002) oriented and were rather smooth with an average surface roughness of +/- 17 Angstrom. An alysis of the oxidation kinetics of the ZrN thin films reveals a therm ally activated, diffusion-limited oxidation process with an activation energy of 2.5 eV in the temperature range of 500-650 degrees C. This implies that there is an advantage in using ZrN as a barrier layer ins tead of TiN since the activation energy for oxidation of TiN is 2.05 e V. In addition, preliminary data suggest that a Pt/Ru double layer may be a promising bottom electrode and oxygen diffusion barrier for use in DRAMs with high-permittivity dielectrics.