Characteristics of ZrO2 thin films deposited by reactive magnetron sputtering

Recently, high-dielectric-constant materials have gained considerable attention as a possible alternative to gate dielectric material. Among the high dielectric materials, ZrO2 is considered to be an attractive material. Thin films of ZrO2 were deposited on silicon substrates by using a r.f. reactive magnetron sputtering technique. To investigate the plasma immersion effect and influence of reactant gas ratio during the sputtering on the electrical and the structural properties of ZrO2 thin films, we used X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM) and I-V measurement were used. The as-deposited ZrO2 films showed a polycrystalline phase. The thicknesses of ZrO2 thin films deposited on silicon were 25 similar to 30 angstrom. The dominant phases of all samples were the monoclinic phase and the tetragonal phase. However, the samples of the immersed state were different from the samples of non-immersed state in the position of the tetragonal peak. The root-mean-square (RMS) surface roughness of the samples deposited by using plasma immersing method was higher than that of the samples deposited by using plasma non-immersing method. The leakage current density of the samples that were deposited by using the plasma immersing method was different from the leakage current density of the samples deposited by using the non-immersing method. The sample that was deposited in 50 % N2O and in a plasma immersing state had the smallest leakage current density (1.28 x 10(-5) A/cm(2) at 2 V).