High dielectric constant hafnium oxide films were formed by electron beam ͑e-beam͒ evaporation on HF last terminated silicon ͑100͒ wafers. We report on the influence of low energy argon plasma ͑ϳ70 eV͒ and oxygen flow rate on the electrical, chemical, and structural properties of metal-insulator-silicon structures incorporating these e-beam deposited HfO 2 films. The use of the film-densifying low energy argon plasma during the deposition results in an increase in the equivalent oxide thickness ͑EOT͒ values. We employ high resolution transmission electron microscopy ͑HRTEM͒, x-ray photoelectron spectroscopy ͑XPS͒, and medium energy ion scattering experiments to investigate and understand the mechanisms leading to the EOT increase. We demonstrate very good agreement between the interfacial silicon oxide thicknesses derived independently from XPS and HRTEM measurements. We find that the e-beam evaporation technique enabled us to control the SiO x interfacial layer thickness down to ϳ6 Å. Very low leakage current density ͑Ͻ10 −4 A / cm 2 ͒ is measured at flatband voltage +1 V into accumulation for an estimated EOT of 10.9Ϯ 0.1 Å. Based on a combined HRTEM and capacitance-voltage ͑CV͒ analysis, employing a quantum-mechanical CV fitting procedure, we determine the dielectric constant ͑k͒ of HfO 2 films, and associated interfacial SiO x layers, formed under various processing conditions. The k values are found to be 21.2 for HfO 2 and 6.3 for the thinnest ͑ϳ6 Å͒ SiO x interfacial layer. The cross-wafer variations in the physical and electrical properties of the HfO 2 films are presented.

Diamond-like carbon (DLC) films were deposited utilising plasma enhanced chemical vapour deposition (PECVD) with acetylene precursor, diluted with 0 -45% argon.Electron paramagnetic resonance (EPR) measurements show the presence of one paramagnetic centre with no change in spin population over the range of film deposition conditions. However, the EPR linewidth decreases with increasing argon content of the precursor mix, suggesting an enhancement of motional narrowing due to an increase in electron delocalization, related to an increase in the sp 2 cluster size.Atomic force microscopy (AFM) measurements indicate the surface of the DLC is formed of nanoscale asperities of material. With radii of tens of nanometres for films deposited with zero argon, the size of the features increases with the argon dilution of the acetylene. Energy dispersive x-ray analysis and electrical measurements further elucidate the changes in film structure.

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Electron paramagnetic resonance (EPR) measurements have been made at X-band and room temperature on monoclinic HfO2 and ZrO2 powders from several suppliers. They reveal the presence of eight main paramagnetic centers H1, H2, H3, H4, and Z1, Z2, Z3, and Z4. H1 and Z1 are analogous as H4 and Z4 and H2 and Z2 are similar as H3 and Z3. H1 and Z1 have axial symmetry with g∥<g⊥<ge, where ge is the free electron g value. H1 is found in all, and Z1 in all but one, of the samples in their as-received state but with a wide range of concentrations. However, annealing the samples in air up to 900 °C reduces the volume concentration range and the areal concentrations all become of order 1011 cm−2. Irradiation with γ-rays does not affect their concentration. The Z1 centers are found to be the same as those previously observed in ZrO2 powders that were attributed to Zr3+ ions in coordinatively unsaturated (cus) sites at and/or near the surface. Our results are consistent with this model for Z1 and with an analogous model of cus Hf3+ for H1. H4 and Z4 are centers of isotropic symmetry with g values that are both within ±0.0004 of 2.0027; they are produced in all HfO2 and ZrO2 samples, respectively, that are heated in vacuum at ≥300 °C. Their concentration reaches a maximum of order 1017 cm−3 or 1012 cm−2 in the range of 550–750 °C. They are also most likely to be mainly at and/or near the surface and to involve an electron trapped in an oxygen vacancy cluster. The EPR spectra of H2 and Z2 are consistent with those of S=1/2 centers of orthorhombic symmetry with principal g values about equal to or just less than ge suggesting that they are trapped electron centers. The electrons produced by γ-irradiation are trapped at precursors to H2 but are easily detrapped. Z2 centers also appear to be shallow electron traps. Their identity is uncertain; they have some characteristics of electrons trapped in oxygen vacancies and of CO2− radicals. H3 and Z3 are likely to involve holes trapped on oxygen, possibly as O− and O2− type centers, respectively, but their location in not known. Their concentration increases to an upper limit as the γ-ray dose is increased and this shows that their precursors are trapping charge generated by the γ-rays. Like the H2 and Z2 centers, even annealing at 100 °C releases the charge but their precursors, at least in HfO2, are not destroyed. The significance of these centers is discussed.

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