Detailed Correlation of Electrical and Breakdown Characteristics to the Structural Properties of ALD Grown HfO2- and ZrO2-based Capacitor Dielectrics

Clear distinctions in the breakdown behavior of crystalline and amorphous dielectrics in MIM capacitors are correlated to different polarity asymmetries in the C-V and I-V characteristics of these symmetrical devices. Physical analysis of the complete capacitor stack reveals an oxidation of the TiN bottom electrode interface, leading to TiON formation and nitrogen diffusion into the dielectric. This can be traced back to the growth behavior of the dielectric on the TiN substrate. The atomic layer deposition caused interface formation is enhanced for crystalline films compared to amorphous, resulting in the asymmetry differences seen in electrical and breakdown characterization. In addition, asymmetrical charge trapping and a higher trap density are assumed for crystalline dielectric. These effects are detected both for doped HfO2 and ZrO2 layers.