Properties Of HfO2 Thin Films Research Articles

Comparison of Electrical and Structural Properties of HfO2 Thin Films on Strained and Relaxed Si1-xGex

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MeV-Si ion irradiation effects on the electrical properties of HfO2 thin films on Si

We studied the irradiation effect of 2-MeV Si ions on HfO2 films deposited on Si substrates. HfO2 films ∼11nm thick were deposited onto 〈100〉 Si substrates by chemical vapor deposition. The samples were then irradiated by 2-MeV Si ions at a fluence of 1×1014cm−2 at room temperature, followed by rapid thermal annealing at 1000°C for 10s. After annealing, a layer of aluminum was deposited on the samples as the gate electrode to form metal-oxide-semiconductor (MOS) capacitor structures. Rutherford backscattering spectrometry and electrical measurement of both capacitance and current as a function of voltage were used to characterize the samples before and after annealing. Non-insulating properties of the HfO2 films deteriorated immediately after the ion irradiation, but rapid thermal annealing effectively repaired the irradiation damages, as reflected in improved capacitance versus voltage characteristics and significant reduction of leakage current in the MOS capacitors.

Comparison between atomic-layer-deposited HfO2 films using O3 or H2O oxidant and Hf[N(CH3)2]4 precursor

The dielectric properties of HfO2 thin films, which were deposited on Si wafers by an atomic layer deposition (ALD) technique at a wafer temperature of 300 °C using a N-containing, tetrakis dimethylamido hafnium precursor (Hf[N(CH3)2]4), were highly improved by adopting O3 as the oxidant during the ALD instead of H2O. The films contained a much smaller carbon impurity concentration and were of more amorphous nature compared to the films grown using H2O as oxidant. Temperature-dependent leakage current analysis showed that the films grown using O3 as oxidant had a higher interfacial potential barrier for tunneling and the leakage current densities of the as-deposited film were three orders of magnitude smaller than that of the films grown using H2O. The dielectric constant of the HfO2 film was 24.4 and the leakage current density was 1.6×10−7A∕cm2 when the capacitance equivalent thickness was 1.49 nm.

Evolution of Sputtered HfO2 Thin Films Upon Annealing

AbstractWe investigated the evolution of the physical and electrical properties of HfO2 thin films deposited by the reactive DC magnetron sputtering method on the (100) silicon substrate upon annealing. The HfO2 thin films deposited at room temperature were amorphous, while the films after annealing were poly crystalline. The crystallization temperature of the HfO2 thin films was dependent on the annealing methods (RTP or Furnace) and ambient (nitrogen or oxygen). The microstructures of HfO2 thin gate oxides of Tox <15A thick were analyzed by HRTEM, XPS and XRD. We also focused on the interfacial layer between HfO2 thin films and silicon substrates. Due to its high oxygen diffusivity, any annealing led to oxygen diffusion rapidly through the HfO2 films. The EOT increased upon annealing due to the increased SiO2-containing layer. The HfO2 thin films deposited at room temperature have the undesirable interfacial states due to the surface damage by sputtering. We found that the HfO2 thin films <15A thick were optimized by RTP or furnace annealing.