A solid state light emitting device composed of the 10 nm thickness zirconium-doped hafnium oxide high-k gate dielectric with or without an embedded nanocrystalline ZnO layer has been fabricated and studied. The emission spectrum, which extended from visible light to IR, was broadened and the intensity was increased with the embedding of a nanocrystalline ZnO layer. The mechanisms of light emission and enhancement were investigated and explained with defect generation process in the film. This kind of device is easily prepared by the IC compatible process. There are many potential applications of this kind of device.

Metal-oxide-semiconductor capacitors made of the nanocrystalline cadmium selenide nc-CdSe embedded Zr-doped HfO2 high-k stack on the p-type silicon wafer have been fabricated and studied for their charge trapping, detrapping, and retention characteristics. Both holes and electrons can be trapped to the nanocrystal-embedded dielectric stack depending on the polarity of the applied gate voltage. With the same magnitude of applied gate voltage, the sample can trap more holes than electrons. A small amount of holes are loosely trapped at the nc-CdSe/high-k interface and the remaining holes are strongly trapped to the bulk nanocrystalline CdSe site. Charges trapped to the nanocrystals caused the Coulomb blockade effect in the leakage current vs. voltage curve, which is not observed in the control sample. The addition of the nanocrystals to the dielectric film changed the defect density and the physical thickness, which are reflected on the leakage current and the breakdown voltage. More than half of the originally trapped holes can be retained in the embedded nanocrystals for more than 10 yr. The nanocrystalline CdSe embedded high-k stack is a useful gate dielectric for this nonvolatile memory device.

Thin films of zirconium-doped tantalum oxide ͑Zr-doped TaO x ) deposited by reactive sputtering were studied in an effort to replace silicon dioxide (SiO 2 ) as the gate dielectric material for future metal-oxide-semiconductor devices. Influences of process parameters, such as Zr concentration, postdeposition annealing temperature, and film thickness, on the film's electrical and physical characteristics were investigated. The lightly Zr-doped film ͑15 nm thick͒ showed a low current density, e.g., 1.27 ϫ 10 Ϫ9 A/cm 2 at Ϫ1 MV/cm in the accumulation regime. The current conduction mechanism of the Zr-doped TaO x films was analyzed and compared with mechanisms of Poole-Frenkel and Schottky emissions. In comparison with pure tantalum oxide (TaO x ) and zirconium oxide (ZrO y ) films, the Zr-doped TaO x films had higher dielectric constants. A high-temperature annealing step reduced the film's hysteresis and fixed charge density. The interface layer composition changed from SiO x to zirconium silicate (Zr x Si y O) when the Zr concentration in the film was increased. The binding energies of Ta 4f, Zr 3d, and O 1s of the bulk shifted to lower values as the Zr concentration increased due to the charge transfer among elements. In summary, the Zr-doped TaO x films showed many advantages over pure TaO x and ZrO y films for the gate dielectric application.

Electrical and optical properties of the solid state incandescent light emitting devices made of zirconium doped hafnium oxide high-k films with and without an embedded nanocrystalline CdSe layer on the p-type Si wafer have been studied. The broad band white light was emitted from nano sized conductive paths through the thermal excitation mechanism. Conductive paths formed from the dielectric breakdown have been confirmed from scanning electron microscopic and atomic force microscopic images and the secondary ion mass spectrometric elemental profiles. Si was diffused from the wafer to the device surface through the conductive path during the high temperature light emission process. There are many potential applications of this type of device.

Ultrathin zirconium-doped hafnium oxide high dielectric constant films, e.g., with an equivalent oxide thickness less than 1 nm, have been prepared by high-power sputtering and low oxygen content annealing conditions on the p-type Si͑100͒ substrate. The influence of the process conditions on the film's material and electrical properties were investigated with X-ray photoelectron spectroscopy analysis and electrical measurements. The low equivalent oxide film also shows a small charge trapping density, a low leakage current density, and a moderate interface state density. This is a viable gate dielectric film for future complementary metal oxide semiconductor devices.The continuous shrinkage of complementary metal oxide semiconductor ͑CMOS͒ device dimensions necessitates the use of a high dielectric constant ͑high-k͒ gate dielectric material to replace the thermal grown silicon dioxide ͑SiO 2 ͒. 1 Metal oxides such as hafnium oxide ͑HfO 2 ͒ and zirconium oxide ͑ZrO 2 ͒ have been extensively studied as the high-k gate dielectric candidates because of their high k values, large electron band offsets to silicon, and good thermal stability in contact with silicon. 2-5 However, both HfO 2 and ZrO 2 crystallize at a relatively low temperature, Ͻ700°C, which is a potential reliability problem. Previously, it was demonstrated that many physical and electrical properties of a metal oxide high-k gate dielectric, such as the amorphous-to-polycrystalline transition temperature, interface layer quality, k value, dielectric breakdown strength, and leakage current density, could be improved by the doping method, i.e., adding a third element into the film. 6-9 For example, the zirconium-doped hafnium oxide ͑Zr-doped HfO 2 ͒ dielectric showed a lower equivalent oxide thickness ͑EOT͒ and smaller interface state density ͑D it ͒ than the undoped HfO 2 . 8 This result is consistent whether the high-k film was deposited by sputtering or atomic layer deposition ͑ALD͒. 8,9 The recent work on the ALD Zr-doped HfO 2 high-k dielectric film demonstrated that the addition of ZrO 2 into HfO 2 would not only help to partially stabilize the tetragonal structure of HfO 2 but also improve the surface morphology of the high-k film, both of which play critical roles in improving device characteristics. 10 Previously, it was reported that a proper amount of dopant in the high-k film can increase its crystallization temperature. 11 The Zr-doped HfO 2 dielectric film in this work is amorphous. 12 In general, the amorphous high-k dielectrics are desirable for uniform dielectric properties and reliability concerns. 1 According to the International Technology Roadmap for Semiconductor ͑ITRS͒, a high-k gate dielectric film with an EOT less than 1 nm will be required for future CMOS applications. 13 In this paper, we have investigated the feasibility of preparing such a gate dielectric by the reactive sputtering method as well as the influences of process conditions to the high-k film's dielectric properties. ExperimentalThe Zr-doped HfO 2 thin film was dep...

No abstract

Physical and electrical properties of hafnium-doped tantalum oxide thin films were studied. The doping process affects the structures, composition, thickness, dielectric constant, charges, and leakage current density of both the bulk film and the interface layer. Compared with the undoped film, the lightly doped film exhibited improved dielectric properties, such as a higher dielectric constant, a smaller fixed charge density, a larger dielectric strength, and a lower leakage current. The postdeposition annealing process condition, such as temperature and time, also influences the high-k film's dielectric properties. In summary, the hafniumdoped tantalum oxide film is a promising high-k gate dielectric material for future metal-oxide-semiconductor devices.

No abstract