Rutile titanium oxide (TiO₂) thin films require more energy to crystallize than the anatase phase of TiO₂. It is a prime candidate for micro-optoelectronics and is usually obtained either by high substrate temperature, applying a substrate bias, pulsed gas flow to modify the pressure, or ex situ annealing. In the present work, we managed to obtain high enough energy at the substrate in order for the particles to form rutile TiO₂ at room temperature without any intentional substrate bias in a continuous gas flow. The rutile TiO₂ thin films were deposited by a reactive radiofrequency magnetron sputtering system from a titanium target, in an argon/oxygen gas mixture. Investigations regarding the film’s structure and morphology were performed by X-ray diffraction (XRD), X-ray reflectivity (XRR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDAX), while the optical properties were investigated by means of ellipsometry.

In this work, we present experimental results examining the energy distribution of the relatively high <mml:math display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:mo></mml:mo><mml:mn>1</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>11</mml:mn></mml:mrow></mml:msup><mml:mspace width="0.3em"></mml:mspace><mml:msup><mml:mi>cm</mml:mi><mml:mrow><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mo>)</mml:mo></mml:mrow></mml:math>(1×1011cm−2) electrically active interface defects which are commonly observed in high-dielectric-constant (high- <mml:math display="inline"><mml:mrow><mml:mi>k</mml:mi></mml:mrow></mml:math>k ) metal–insulator–silicon systems during high- <mml:math display="inline"><mml:mrow><mml:mi>k</mml:mi></mml:mrow></mml:math>k process development. This paper extends previous studies on the <mml:math display="inline"><mml:mrow><mml:mi>Si</mml:mi><mml:mo>(</mml:mo><mml:mn>100</mml:mn><mml:mo>)</mml:mo><mml:mo>∕</mml:mo><mml:msub><mml:mi>SiO</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mo>∕</mml:mo><mml:msub><mml:mi>HfO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Si(100)∕SiOx∕HfO2 system to include a comparative analysis of the density and energy distribution of interface defects for <mml:math display="inline"><mml:mrow><mml:msub><mml:mi>HfO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>HfO2 , lanthanum silicate <mml:math display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi>LaSiO</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:mo>)</mml:mo></mml:mrow></mml:math>(LaSiOx) , and <mml:math display="inline"><mml:mrow><mml:msub><mml:mi>Gd</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Gd2O3 thin films on (100) orientation silicon formed by a range of deposition techniques. The analysis of the interface defect density across the energy gap, for samples which experience no <mml:math display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">H</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>∕</mml:mo><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>H2∕N2 annealing following the gate stack formation, reveals a peak density ( <mml:math display="inline"><mml:mrow><mml:mo>∼</mml:mo><mml:mn>2</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>12</mml:mn></mml:mrow></mml:msup><mml:mspace width="0.3em"></mml:mspace><mml:msup><mml:mi>cm</mml:mi><mml:mrow><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mspace width="0.3em"></mml:mspace><mml:msup><mml:mi>eV</mml:mi><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>∼2×1012cm−2eV−1 to <mml:math display="inline"><mml:mrow><mml:mo>∼</mml:mo><mml:mn>1</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>13</mml:mn></mml:mrow></mml:msup><mml:mspace width="0.3em"></mml:mspace><mml:msup><mml:mi>cm</mml:mi><mml:mrow><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup><mml:mspace width="0.3em"></mml:mspace><mml:msup><mml:mi>eV</mml:mi><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>∼1×1013cm−2eV−1 ) at <mml:math display="inline"><mml:mrow><mml:mn>0.83</mml:mn><mml:mo>–</mml:mo><mml:mn>0.92</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>eV</mml:mi></mml:mrow></mml:math>0.83–0.92eV above the silicon valence bandedge for the <mml:math display="inline"><mml:mrow><mml:msub><mml:mi>HfO</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>HfO2 , <mml:math display="inline"><mml:mrow><mml:msub><mml:mi>LaSiO</mml:mi><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>LaSiOx , and <mml:math display="inline"><mml:mrow><mml:msub><mml:mi>Gd</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Gd2O3 thin films on <mml:math display="inline"><mml:mrow><mml:mi>Si</mml:mi><mml:mo>(</mml:mo><mml:mn>100</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:math>Si(100) . The characteristic peak in the interface state density <mml:math display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:mn>0.83</mml:mn><mml:mo>–</mml:mo><mml:mn>0.92</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>eV</mml:mi><mml:mo>)</mml:mo></mml:mrow></mml:math>(0.83–0.92eV) is obtained for samples where no interface silicon oxide layer is observed from transmission electron microscopy. Analysis suggests silicon dangling bond <mml:math display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi>P</mml:mi><mml:mi>bo</mml:mi></mml:msub><mml:mo>)</mml:mo></mml:mrow></mml:math>(Pbo) centers as the common origin for the dominant interface defects for the various <mml:math display="inline"><mml:mrow><mml:mi>Si</mml:mi><mml:mo>(</mml:mo><mml:mn>100</mml:mn><mml:mo>)</mml:mo><mml:mo>∕</mml:mo><mml:msub><mml:mi>SiO</mml:mi><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>Si(100)∕SiOx /high- <mml:math display="inline"><mml:mrow><mml:mi>k</mml:mi></mml:mrow></mml:math>k /metal gate systems. The results of forming gas <mml:math display="inline"><mml:mrow><mml:mo>(</mml:mo><mml:msub><mml:mi mathvariant="normal">H</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>∕</mml:mo><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>)</mml:mo></mml:mrow></mml:math>(H2∕N2) annealing over the temperature range <mml:math display="inline"><mml:mrow><mml:mn>350</mml:mn><mml:mo>–</mml:mo><mml:mn>555</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>350–555°C are presented and indicate interface state density reduction, as expected for silicon dangling bond centers. The technological relevance of the results is discussed.

The fabrication of oxynitrides using low thermal budget process technology is a key component in the production of advanced devices. This work focuses on the use of plasma anodization of low-pressure chemical vapor deposition (LPCVD) silicon nitride films to produce silicon oxynitride films, which are characterized structurally and electrically. The oxynitride dielectric films have a three layer structure, with “SiO2”-like layers at the surface and near the interface, and a “Si3N4”-like layer between them. Hence, nitrogen atoms are replaced by oxygen atoms at the surface of the film and near the Si/dielectric interface. The conductivity of the silicon nitride film was found to be higher than the silicon oxynitride film, whereas the conductivity of the oxynitride and, therefore, its trapping characteristics are more temperature dependent. Furthermore, the activation energy required to release an electron from a trap in the silicon oxynitride film (0.218 eV) is 1.7× that of the silicon nitride film (0.130 eV). Although oxidation of the LPCVD silicon nitride film did not reduce the interface trap density (≅1012 cm−2 eV−1 for both Si3N4 and SiON films), the density of traps, which are thought to be silicon dangling bonds in the form of an sp3 state near midgap, have reduced. A model to explain the conduction properties of the silicon oxynitride film—based on the Fowler–Nordheim conduction mechanism—was developed. Moreover, this model takes into account the trapping dynamics of the film. It was found that the best theoretical fit to the experimental current density data was obtained by assuming that the areal trap density, No,=5×1012 cm−2 and the trap capture cross section, σ=1×10−16 cm2.