Investigation of MOS Capacitors with Thin ZrO₂ Layers and Various Gate Materials for Advanced DRAM Applications

Thin ZrO₂ layers were used to realize MOS capacitors with aluminum, polysilicon, and molybdenum gate electrodes. The layers, 300–600 A in thickness, were obtained by metal organic chemical vapor deposition. The effects of various high-temperature treatments as well as gate material deposition conditions on the MOS capacitor properties were studied. Processing conditions compatible with standard silicon technology were established to obtain capacitors suitable for advanced DRAM application. Relative dielectric constant e ≥ 16, breakdown field E_B≥ 3 MV/cm, and leakage currents at applied voltage of 5 V around 10^-8 A/cm² enable the realization of capacitors with dielectric layer equivalent to 35 A of SiO₂.