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The effects of CF4 plasma treatment on Gd2O3 nanocrystal (NC) memory were investigated. For material analysis, secondary ion mass spectrometry and x-ray photoelectron spectroscopy analyses were performed to characterize the fluorine depth profile of the Gd2O3-NC film. In addition, an UV-visible spectrophotometer was used to obtain the Gd2O3 bandgap and analyzed to suggest the modified structure of the energy band. Moreover, the electrical properties, including the memory window, program/erase speed, charge retention, and endurance characteristics were significantly improved depending on the CF4 plasma treatment conditions. This can be explained by the physical model based on the built-in electric field in the Gd2O3 nanostructure. However, it was observed that too much CF4 plasma caused large surface roughness induced by the plasma damage, leading to characteristics degradation. It was concluded that with suitable CF4 plasma treatment, this Gd2O3-NC memory can be applied to future nonvolatile memory applications. [ABSTRACT FROM AUTHOR]

A detailed study of soft breakdown modes for hafnium oxynitride (HfON) gate dielectrics under stress is investigated. Two types of soft breakdown, digital and analog modes, are observed in HfON gate dielectrics, featuring gate voltage fluctuation accompanying random telegraph noise and nonswitching 1/f noise, respectively. The dependence of gate area, oxide thickness, and stress current density on breakdown modes is also studied. Thin oxide thickness and small gate area contribute to the enhancement of charge to breakdown (Qbd). Large Joule heat damage generated under stress inducing the analog soft breakdown for thick hafnium oxynitride films is proposed to clearly understand the breakdown of HfON gate dielectrics. [ABSTRACT FROM AUTHOR]

Data retention characteristics of tungsten nanocrystal (W-NC) memory devices using an oxygen plasma immersion ion implantation (PIII) treatment are investigated. With an increase of oxygen PIII bias voltage and treatment time, the capacitance-voltage hysteresis memory window is increased but the data retention characteristics become degraded. High-resolution transmission electron microscopy images show that this poor data retention is a result of plasma damage on the tunneling oxide layer, which can be prevented by lowering the bias voltage to 7 kV. In addition, by using the elevated temperature retention measurement technique, the effective charge trapping level of the WO3 film surrounding the W-NCs can be extracted. This measurement reveals that a higher oxygen PIII bias voltage and treatment time induces more shallow traps within the WO3 film, degrading the retention behavior of the W-NC memory. [ABSTRACT FROM AUTHOR]

Characteristics improvement of gadolinium oxide (GdxOy) resistive random access memories (RRAMs) treated by hydrogen plasma immersion ion implantation (PIII) was investigated. With the hydrogen PIII treatment, the GdxOy RRAMs exhibited low set/reset voltages and a high resistance ratio, which were attributed to the enhanced movement of oxygen ions within the GdxOy films and the increased Schottky barrier height at Pt/GdxOy interface, respectively. The resistive switching mechanism of GdxOy RRAMs was dominated by Schottky emission, as proved by the area dependence of the resistance in the low resistance state. After the hydrogen PIII treatment, a retention time of more than 104s was achieved at an elevated measurement temperature. In addition, a stable cycling endurance with the resistance ratio of more than three orders of magnitude of the GdxOy RRAMs can be obtained. [ABSTRACT FROM AUTHOR]

Nanostructure band engineering accomplished by CF4 plasma treatment on Gd2O3 nanocrystal memory was investigated. Under the CF4 plasma treatment, the fluorine was incorporated into the Gd2O3 film and resulted in the modification of energy-band. A physical model was proposed to explain the relationship between the built-in electric field in Gd2O3 nanostructure and the improved program/erase (P/E) efficiency and data retention characteristics. The memory window of the Gd2O3–NC memory with CF4 plasma treatment and postplasma annealing was increased to 3.4 V after 104 P/E cycling. It is demonstrated that the Gd2O3–NC memory with nanostructure band engineering is promising for future nonvolatile memory application. [ABSTRACT FROM AUTHOR]

In this letter, the effects of pre-CF4 plasma treatment on Si for sputtered HfO2 gate dielectrics are investigated. The significant fluorine was incorporated at the HfO2/Si substrate interface for a sample with the CF4 plasma pretreatment. The Hf silicide was suppressed and Hf–F bonding was observed for the CF4 plasma pretreated sample. Compared with the as-deposited sample, the effective oxide thickness was much reduced for the pre-CF4 plasma treated sample due to the elimination of the interfacial layer between HfO2 and Si substrate. These improved characteristics of the HfO2 gate dielectrics can be explained in terms of the fluorine atoms blocking oxygen diffusion through the HfO2 film into the Si substrate. [ABSTRACT FROM AUTHOR]

In this letter, we reported a high-k gadolinium oxide (Gd2O3) gate dielectric formed by reactive rf sputtering. It is found that the Gd2O3 gate dielectric film exhibits excellent electrical properties such as low leakage current density, high breakdown voltage, and almost no hysteresis and frequency dispersion in C-V curves comparable to that of HfO2 film. This indicates that postprocessing treatments can reduce a large amount of interface trap and can passivate a large amount of trapped charge at defect sites. [ABSTRACT FROM AUTHOR]

In this paper, fluorine incorporation into the HfO2 gate dielectrics by post CF4 plasma treatment was proposed to improve the electrical characterization. TaN–HfO2–p-Si capacitors were demonstrated in this work. The characteristics of fluorinated HfO2 gate dielectrics were improved, including the capacitance-voltage hysteresis and current-voltage behaviors. This may be attributed to the fluorine incorporated into the HfO2 gate dielectrics as revealed by secondary ion mass spectroscopy. Moreover, the formation of Hf-F bonding was observed through electron spectroscopy for chemical analysis spectra. [ABSTRACT FROM AUTHOR]