The structural and electrical characterization of a HfErO _x dielectric for MIM capacitor DRAM applications

Hafnium erbium oxide (HfErO _x) thin films were formed using atomic layer deposition. The effect of using different Hf:Er pulse ratios on the electrical and structural properties of the HfErO _x thin films (∼9 nm) in metal-insulator-metal (MIM) capacitor structures have been investigated and comparisons made between as-deposited and annealed samples. We report the stabilisation of the higher dielectric constant (k) tetragonal/cubic phase by optimising the Hf:Er pulse ratio. The dielectric properties post thermal anneal at 500°C were studied. A leakage current in the order of ∼1 × 10 ^-8 (A/cm ²) at a voltage of 1 V and a capacitance equivalent thickness of ∼1.4 nm have been achieved post thermal annealing at 500°C.