Improved EOT and leakage current for metal–insulator–metal capacitor stacks with rutile TiO2

Abstract: Downscaling of the metal–insulator–metal capacitor (MIMCAP) for Dynamic Random Access Memory (DRAM) requires the introduction of high permittivity dielectrics. MIMCAP structures formed with RuO2/Ru as bottom electrode, rutile TiO2 as dielectric and TiN as top electrode are described. Ozone (O3) is needed as oxidant in the TiO2 atomic layer deposition (ALD) process in order to obtain the rutile phase (permittivity>80), while anatase TiO2 (permittivity ∼40) is obtained with H2O. As O3 etches the ruthenium substrate, an ultra-thin interlayer of TiO2 was first grown with H2O, followed by the thick TiO2 layer deposited with O3. In order to minimize the content of anatase in the TiO2 layer, responsible for a reduced dielectric constant, we investigate the effect of scaling down the thickness of the protective H2O based inter-layer on the equivalent oxide thickness (EOT) and leakage current density (J g). The four times reduction in thickness without affecting the integrity of the ruthenium substrate resulted in a significant decrease of both EOT and J g. [Copyright &y& Elsevier]