ATOMIC LAYER DEPOSITION TIN BARRIER LAYERS FOR THROUGH SILICON VIA APPLICATIONS

Atomic layer deposited TiN thin films on SiO2/Si for Through Silicon Via applications were investigated in this paper. TiCl4 and NH3 were used as the source and reactant gases, respectively. The thin films were deposited at the temperature range between 350 degrees C and 500 degrees C. Difference analysis methods, including AES, XRD, four-point probe and ellipsometer were employed to evaluate the properties of deposited TiN films. The measured deposition rate of TiN films is about 0.15 angstrom/cycle, independent from the process condition, which indicates the growth mechanism of ALD. Resistivity of deposited thin films was measured by a four-point probe and the relationship between the resistivity and deposition temperature was investigated. Resistivity of the films is less than 125 mu Omega.cm when deposition temperature is above 400 degrees C, which decreases when the deposition temperature increases, as well as the film thickness. TiN film was grown with [100] preferred orientation at 350 degrees C, while with [111] preferred orientation at 400 degrees C and higher temperatures. Chemical composition was analyzed by AES, the content of chorine in TiN films is about 1.5 at. % at the deposition temperature of 350 degrees C, and it decrease to 0.5 at. % when the deposition temperature is above 350 degrees C. In order to investigate the performance of TiN as diffusion barrier layer, the structure of Cu/TiN/SiO2/Si was prepared. Annealing of the samples were performed in a vacuum ambient of 10(-5) Pa at selected temperatures for 1h. XRD analysis results indicate that no copper diffusion into the SiO2 for Si with Cu/TiN/SiO2 films after annealing below 500 degrees C.