Electrical and Reliability Characteristics of MOS Devices With Ultrathin $\hbox{SiO}_{2}$ Grown in Nitric Acid Solutions
TL;DR: In this article, the electrical and reliability properties of ultrathin silicon dioxide, grown by immersing silicon in nitric acid solution have been studied, and it is observed that the temperature, oxidation time, and concentration of the nitric acids solution play important roles in determining the thickness as well as the quality of the oxide.
Abstract: In this paper, electrical and reliability properties of ultrathin silicon dioxide, grown by immersing silicon in nitric acid solution have been studied. It is observed that the temperature, oxidation time, and concentration of the nitric acid solution play important roles in determining the thickness as well as the quality of the oxide. Prolonged exposure to nitric acid degrades the quality of the oxide. However, it was found necessary to reduce the oxidation temperature and the concentration of nitric acid to grow oxide of thickness 2 nm. In these conditions, the leakage current and fixed oxide charge in the chemical oxide were found to be too high. However, when this chemical oxidation was followed by anodic oxidation using ac bias, the electrical and reliability characteristics of metal-oxide-semiconductor (MOS) devices showed tremendous improvement. A MOSFETs with gate oxide grown by this technique have demonstrated low subthreshold slope, high transconductance and channel mobility. It is thus proposed that chemical oxidation followed by ac anodization can be a viable alternative low-temperature technique to grow thin oxides for MOS application.
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TL;DR: In this paper, a dielectric stack with Al2O3/HfO2/SiO2 (18 nm/16 nm/25 nm) trilayer structure prepared by low temperature in situ natural oxidation during dc sputtering is investigated.
Abstract: In this work, a dielectric stack with Al2O3/HfO2/SiO2 (18 nm/16 nm/25 nm) trilayer structure prepared by low temperature in situ natural oxidation during dc sputtering is investigated We study the electrical characteristics, including the dielectric leakage of 10−8 A/cm2 at Vg=−2 V, the current transport mechanism and trap distributions through the trilayer dielectric stack The Fowler–Nordheim barrier height of the prepared Al2O3 (ϕFN,Al2O3) was extracted as 306±015 eV The current variation ratios [ΔJg/Jg(0)] during constant voltage stressing were found to decrease with raising gate stress voltages for the trilayer stack in comparison with that [ΔJg/Jg(0)] increase with raising gate stress voltages for the two-layer HfO2/SiO2 stack Shallow traps located in HfO2 were supposed to be major trapping centers within the trilayer stack The proposed method of in situ oxidation during dc sputtering is of merit and low in process temperature The trilayer dielectric stacks are an alternative option for no
21 citations
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19 Dec 2012
TL;DR: Semiconductor-based ultraviolet photodiodes have been continuously developed that can be widely used in various commercial, civilian areas, and military applications, such as optical communications, missile launching detection, flame detection, UV radiation calibra- tion and monitoring, chemical and biological analysis, optical communications and astro- nomical studies, etc as mentioned in this paper.
Abstract: Semiconductor-based ultraviolet (UV) photodiodes have been continuously developed that can be widely used in various commercial, civilian areas, and military applications, such as optical communications, missile launching detection, flame detection, UV radiation calibra‐ tion and monitoring, chemical and biological analysis, optical communications, and astro‐ nomical studies, etc. [1-2]. All these applications require very sensitive devices with high responsivity, fast response time, and good signal-to-noise ratio is common desirable charac‐ teristics. Currently, light detection in the UV spectral range still uses Si-based optical photo‐ diodes. Due to the Si-based photodiodes are sensitive to visible and infrared radiation, the responsivity in the UV region is still low [3-5]. To avoid these disadvantages, wide-bandgap materials (such as diamond, SiC, III-nitrides and wide-bandgap II–VI materials) are under intensive studies to improve the responsivity and stability of UV photodiodes, because of their intrinsic visible-blindness [6].
10 citations
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TL;DR: In this article, the oxide layer on the surface of a p-type silicon substrate was grown under various growth times and temperatures while under nitric acid treatment, and an efficiency improvement of absolute 2% was obtained using their laboratory fabrication process.
Abstract: In this study, we investigate the effect of nitric acid oxidation on p-type silicon solar cells. The oxide layer on the surface of a p-type silicon substrate was grown under various growth times and temperatures while under nitric acid treatment. After 30 min of growth at 23 °C, an efficiency improvement of absolute 2% was obtained using our laboratory fabrication process.
9 citations
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TL;DR: In this article, a tilted-substrate sputtering technique, which provides various film thicknesses in one processing step, was proposed and useful for the characterization of charge distribution in low-temperature dielectric stacks with anodic oxide interfacial layer (ANO-IL).
Abstract: Hafnium oxide dielectric stacks with anodic oxide interfacial layer (ANO-IL) were investigated under low-temperature consideration. A tilted-substrate sputtering technique, which provides various film thicknesses in one processing step, was proposed and useful for the characterization of charge distribution. It was found that charges existed in the HfO2/ANO-IL were smaller than that in HfO2/rapid-thermal-oxidation IL. The prepared samples exhibit good electrical characteristics, including small electrical hysteresis (< 10 mV), low leakage current, high effective dielectric breakdown field of 12.7 MV/cm, and maximum operating voltages of -2.74 V at 25degC and -2.32 V at 125degC for EOT = 2.3 nm stacks under a ten-year lifetime evaluation. The results suggest that the quality of IL in the dielectric stack is a critical reliability issue and that ANO is provided as a candidate for IL consideration of low-temperature dielectric stacks.
7 citations
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References
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TL;DR: In this paper, the leakage current of the SiO2 layer formed with 61 wt'% HNO3 at its boiling temperature of 113'°C has a 1.3 nm thickness with a considerably high density leakage current.
Abstract: Ultrathin silicon dioxide (SiO2) layers with excellent electrical characteristics can be formed using the nitric acid oxidation of Si (NAOS) method, i.e., by immersion of Si in nitric acid (HNO3) solutions. The SiO2 layer formed with 61 wt % HNO3 at its boiling temperature of 113 °C has a 1.3 nm thickness with a considerably high density leakage current. When the SiO2 layer is formed in 68 wt % HNO3 (i.e., azeotropic mixture with water), on the other hand, the leakage current density (e.g., 1.5 A/cm2 at the forward gate bias, VG, of 1 V) becomes as low as that of thermally grown SiO2 layers, in spite of the nearly identical SiO2 thickness of 1.4 nm. Due to the relatively low leakage current density of the NAOS oxide layer, capacitance–voltage (C–V) curves can be measured in spite of the ultrathin oxide thickness. However, a hump is present in the C–V curve, indicating the presence of high-density interface states. Fourier transformed infrared absorption measurements show that the atomic density of the SiO...
193 citations
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TL;DR: In this article, the present understanding of wear-out and breakdown in ultrathin (t/sub ox/ < 5.0 nm) SiO/sub 2/ gate dielectric films and issues relating to reliability projection are reviewed.
Abstract: The present understanding of wear-out and breakdown in ultrathin (t/sub ox/ < 5.0 nm) SiO/sub 2/ gate dielectric films and issues relating to reliability projection are reviewed in this article. Recent evidence supporting a voltage-driven model for defect generation and breakdown, where energetic tunneling electrons induce defect generation and breakdown will be discussed. The concept of a critical number of defects required to cause breakdown and percolation theory will be used to describe the observed statistical failure distributions for ultrathin gate dielectric breakdown. Recent observations of a voltage dependent voltage acceleration parameter and non-Arrhenius temperature dependence will be presented. The current understanding of soft breakdown will be discussed and proposed techniques for detecting breakdown presented. Finally, the implications of soft breakdown on circuit functionality and the applicability of applying current reliability characterization and analysis techniques to project the reliability of future alternative gate dielectrics will be discussed.
145 citations
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TL;DR: A review of the most common dielectric reliability measurement methods can be found in this paper, where a broad number of different measurement techniques are described in detail for which the set up of the measurement and its stress parameters are clarified.
Abstract: Reliability of thin dielectric films such as silicon dioxide grown on single crystalline silicon is of great importance for integrated circuits of present and future technologies. For the characterization of the quality of dielectric films, it is essential to have measurement methods available which can give a measure of dielectric reliability in a relatively short time. Stress biases are usually highly accelerated and cause destructive dielectric breakdown. Testing for dielectric reliability has been performed for more than 30 years, and in that time many different stress methods have been established. This article reviews that most common dielectric reliability measurement methods and gives practical guidelines to the reliability engineer in the field of dielectric characterization. The examples and data shown here are mainly from MOS gate oxides. The aim of this review paper is to emphasize advantages and disadvantages of the various stress methods. Appropriate dielectric stress methods are pointed out for applications such as process development, process characterization, pocess control and screening (burn-in). A broad number of different measurement techniques are described in detail for which the set up of the measurement and its stress parameters are clarified. Suitable dielectric test structures and the determination of the correct voltage and thickness of the dielectric are discussed; they are essential to determine the electric field across the thin film. The identification of dielectric breakdown and the interpretation and significance of the measurement results are reviewed. A good understanding of the stress method and the various measured parameters is essential to draw correct conclusions for the lifetime of the dielectric at operating conditions. The commonly used, basic analysis techniques for the measurement results are illustrated. Finally, the influence of stress-induced leakage currents on the dielectric reliability characterization is discussed and other aspects relating to very thin oxides of future technologies are briefly described. The paper also includes a large bibliography of more than 250 references.
87 citations
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TL;DR: In this article, the amount of the energy shift of the substrate Si 2p3/2 peak measured as a function of the bias voltage was analyzed for 3.6-nm-thick silicon oxide/n-Si(100) metal-oxide-semiconductor devices.
Abstract: Interface states in the Si band gap present at oxide/Si(100) interfaces for ∼3‐nm‐thick Pt/2.1∼3.6‐nm‐thick silicon oxide/n‐Si(100) metal–oxide–semiconductor devices are investigated by measurements of x‐ray photoelectron spectra under biases between the Pt layer and the Si substrate, and their energy distribution is obtained by analyzing the amount of the energy shift of the substrate Si 2p3/2 peak measured as a function of the bias voltage. All the interface states observed using this new technique have discrete energy levels, showing that they are due to defect states. For the oxide layer formed in H2SO4+H2O2, the interface states have three density maxima at ∼0.3, ∼0.5, and ∼0.7 eV above the valence‐band maximum (VBM). For the oxide layer produced in HNO3, two density maxima appear at ∼0.3 and ∼0.7 eV above the VBM. The energy distribution for the oxide layer grown in HCl+H2O2 has one peak at ∼0.5 eV. The 0.5 eV interface state is attributed to the isolated Si dangling bond defect. The 0.3 and 0.7 eV ...
54 citations
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