Analysis of gate oxide damage by ultraviolet light during oxide deposition in high density plasma

The UV-induced damages to the gate oxide in a commercially available high-density-plasma dielectric oxide deposition system for the ultra-large integrated circuit fabrication process were analyzed systematically using the metal-oxide-semiconductor capacitors with different antenna ratio. UV-induced damages exclusively in the gate oxide were evaluated by depositing 2500 Å thick oxide layer only once and twice on the two wafers separately and comparing the two results: the deposition of the oxide layer of only 2500 Å did not cause any degradation in the SPDM wafer while the double deposition revealed antenna-ratio dependent shift of the breakdown voltage. The deviation of the values of breakdown voltage of the damaged wafer from its normal ones was found mainly at the center of the wafer where the intensity of the UV light is generally higher in the inductively coupled plasma source.     

Stability of dimethyldioctadecylammonium bromide Langmuir-Blodgett films on mica in aqueous salt solutions—implications for surface force measurements

Langmuir-Blodgett (LB) monolayer films of dimethyldioctadecylammonium bromide (DDOA) on muscovite mica have been studied using Wilhelmy plate type wetting measurements, surface force measurements, atomic force microscopy (AFM), and Brewster angle microscopy (BAM) on insoluble monolayers of DDOA before deposition. In particular, the effect of exposure to aqueous KBr salt solutions was investigated. BAM shows a heterogeneous monolayer with small condensed domains of dendritic shape under conditions normally used for deposition. A stick-jump behaviour of the meniscus is seen during deposition, leading to a large-scale heterogeneity measurable in wetting studies. These also show breakdown and hydrophilization of the LB film at the three-phase contact line (meniscus) and when exposed to salt solutions of approximately 10⁻² M concentration. The advancing contact angle against water is approximately 105°. Surface force measurements show long-range attraction in water, but also a surface charge which depends on salt concentration, and breakdown when surfaces are brought into contact in high salt concentrations. AFM images of untreated films show small holes, and breakdown when exposed to salt solution, especially at the three-phase line. The LB film is judged to be less suitable as a model hydrophobic surface owing to its heterogeneity and instability in salt solution.     

探讨电弧离子镀中“大颗粒”净化方法

传统电弧离子镀存在着大颗粒污染、沉积温度相对较高和易引发微弧击穿效应等诸多不足,制约其在精细薄膜、低温沉积和功能薄膜等方面的应用。本文简要介绍了电弧离子镀中大颗粒的形成机理,旨在探讨用磁场控制、脉冲电弧、磁过滤及脉冲偏压等方法来减少大微粒污染及其作用机理。     

Studying energy evolution in the discharge chamber of a multichamber lightning protection system

We present experimental data on the distribution of energy deposition along the discharge chamber of a multichamber lightning protection system at the initial stage of a discharge process modeling a lightning current pulse with 10 kA amplitude. The multichamber system comprised serially connected gas-discharge chambers. The breakdown between electrodes situated on the bottom of a channel in each chamber induces the formation of a shock wave. Subsequent energy evolution during the development of discharge proceeds in the entire volume bounded by the shock wave.     

Aluminium nitride deposition on 4H-SiC by means of physical vapour deposition

190 nm thick aluminium nitride (AlN) with a dielectric constant of 8.8 was deposited by physical vapour deposition (PVD) on n- and p-type Si and n-type 4H-SiC samples. The Metal–Insulator–Semiconductor, MIS, structures were analysed by IV and CV techniques and 1.2 kV SiC diodes were used to evaluate leakage current before and after AlN deposition. The samples were prepared both with and without 5% HF dip after UV exposure, prior to the AlN deposition. Structural AlN analysis showed polycrystalline composition with a dominant [002] phase, a density of 3.27 g/cm³ and stochiometry of Al_0.4N_0.6. Surface pre-treatment did not have much influence on the IV characteristics of Si samples (breakdown field ∼3 MV/cm). However, the non-HF-etched sample is characterised by 2.5 times smaller CV hysteresis for the p-type sample at 100 kHz. The SiC MIS structures have a high leakage current, nevertheless a beneficial influence of UV irradiation is observed in the case of the non-HF-etched sample (soft breakdown field ∼3 MV/cm compared to ∼2 MV/cm for HF-etched sample). The diode reverse current was about 2 pA before UV irradiation and 4 and 600 pA after AlN deposition at room temperature and at 150 °C, respectively.     

Dielectric integrity of ion beam deposited aluminum oxide films in the 10-100 nm thickness range

Catastrophic electrical breakdown of thin Al₂O₃ reader gap films is becoming increasingly important for Giant Magneto-Resistive (GMR) recording heads. In this paper, we study the dielectric integrity of thin Al₂O₃ films in the 10-100 nm thickness range produced by ion beam deposition. The effects of substrate preparation, film thickness and assist beam parameters on electric breakdown are investigated. It was found that optimized films produced using an Al₂O₃ target break down at electric field strengths in the 8.5-9 MV/cm range.     

半绝缘多晶硅薄膜的钝化与性能研究

通过LPCVD的方法,在Si基体表面制备了掺氧半绝缘多晶硅薄膜(SIPOS),分析了钝化机理,讨论了不同流量比与沉积速率、含氧量的关系以及SIPOS膜的含氧量对膜系结构、电阻率、折射率的性能影响,获得了最佳钝化条件,测试结果表明SIPOS薄膜晶体管击穿电压高、可靠性好、性能更稳定,可以满足现代生产的需要.     

Arsenic-doped Ge-spiked monoemitter SiGe:C heterojunction bipolar transistors by low-temperature trisilane based chemical vapor deposition

In this work we optimized the Ge-spiked monoemitter for the SiGe:C heterojunction bipolar transistor by using low-temperature trisilane based chemical vapor deposition to meet the requirements of high growth rate and high electrically-active doping levels of arsenic. The resultant devices show improvement of open-base breakdown voltage and no degradation of cutoff frequency with incorporation of a Ge spike in the monoemitter.     

Characterization of the aqueous peroxomethod for the synthesis of transparent TiO2 thin films

This article summarizes our progress made on an aqueous chemical solution deposition method used for the deposition of photocatalytically active TiO₂ thin films. Starting from Titanium(IV)butoxide we achieved a stable titanium precursor solution containing titanium-peroxo compounds by reaction between Titanium(IV)butoxide and hydrogen peroxide. We were able to deposit anatase TiO₂ films with good optical transparency and abrasion resistance. Dip-coating was used to deposit thin films on glass substrates from the solution. The occurring reaction mechanism was examined via thermal analysis, mass spectrometry and Raman spectroscopy. Decomposition of organic polluents was confirmed by the breakdown of ethanol. The obtained results show promising possibilities of this low-carbon containing synthesis method towards transparent, photocatalytic coatings. Presence of carbon was minimized by avoiding organic complexing agents. These materials are of great importance in the synthesis of self-cleaning materials.     

Electrical insulation and bending properties of SiOx barrier layers prepared on flexible stainless steel foils by different preparing methods

Stainless steel foils on which flexible display devices and integrated solar modules are prepared need to be coated by barrier layers for electrical insulation. In this study, SiO_x barrier layer was prepared on steel foils (SUS 304) by ion beam assisted deposition, Sol-gel deposition and plasma enhanced chemical vapor deposition, respectively. The electrical properties of the SiO_x films, such as resistance, reactance, leakage current density, breakdown field strength and performance index were investigated, and the bending properties were evaluated by bending tests. The best electrical insulation and bending properties of barrier could be achieved with 4 μm thick SiO_x layer prepared by plasma enhanced chemical vapor deposition.     

Electrical breakdown and nanogap formation of indium oxide core/shell heterostructure nanowires

We report the electrical breakdown behavior and subsequent nanogap formation of In(2)O(3)/InO(x) core/shell heterostructure nanowires with substrate-supported and suspended structures. The radial heterostructure nanowires, composed of crystalline In(2)O(3) cores and amorphous In-rich shells, are grown by chemical vapor deposition. As the nanowires broke down, they exhibited two distinct current drops in the current-voltage characteristics. The tips of the broken nanowires were found to have a cone or a volcano shape depending on the width of the nanowire. The shape, the size, and the position of the nanogap depend strongly on the device structure and the nanowire dimensions. The substrate-supported and the suspended devices exhibit distinct breakdown behavior which can be explained by the diffusive thermal transport model. The breakdown temperature of the nanowire is estimated to be about 450?K, close to the melting temperature of indium. We demonstrated the usefulness of this technique by successful fabrication of working pentacene field-effect transistors.     

Nitrogen dilution effects on structural and electrical properties of hot-wire-deposited a-SiN:H films for deep-sub-micron CMOS technologies

Hot-wire chemical vapor-deposited silicon nitride is a potential dielectric material compared to glow-discharge-deposited material due to its lower hydrogen content. In several earlier publications we have demonstrated these aspects of the HWCVD nitride. However, to replace SiO₂ with a-SiN:H as the gate dielectric, this material needs further improvement. In this paper we report the results of our efforts to achieve this through nitrogen dilution of the SiH₄+NH₃ gas mixture used for deposition. To understand the electrical behavior of these nitride films, we characterized the films by high-frequency capacitance–voltage (HFCV) and DC J–E measurements. We attempted to evolve a correlation between the breakdown strength, as determined from the J–E curves, and aspects such as the bond density, etching rate, deposition rate and refractive index. From these correlations, we infer that nitrogen dilution of the source gas mixture has a beneficial effect on the physical and electrical properties of the hot-wire a-SiN:H films. For the highest dilution, we obtained a breakdown voltage of 12 MV cm⁻¹.     

Zirconia and hafnia films from single source molecular precursor compounds: Synthesis, characterization and insulating properties of potential high k-dielectrics

Novel hafnium and zirconium complexes with oximato ligands are used for chemical solution deposition of zirconia and hafnia thin films. X-ray diffraction and high resolution transmission electron microscopy reveal an amorphous microstructure. Scanning electron as well as atomic force microscopy show uniform and smooth films of both oxides. Electrical breakdown measurements are carried out in order to evaluate the application potential of the hafnia and zirconia thin films as dielectric layers in thin film transistors.     

Room temperature electroluminescence from arsenic doped p-type ZnO nanowires/n-ZnO thin film homojunction light-emitting diode

The highly arrayed arsenic doped p-ZnO nanowires/n-ZnO thin film homojunction light-emitting diode was fabricated on semi-insulated Si substrate. The homojunction was consisted of high-quality n-ZnO thin film grown by metal–organic chemical vapor deposition technology following arsenic doped ZnO nanowires grown by chemical vapor deposition. The device shows good rectification characteristic with a turn-on voltage of ~4.8 V and reverse breakdown voltage of ~18 V. Moreover, two distinct electroluminescence bands centered at 2.35 and 3.18 eV are detected from this device under forward bias at room temperature.     

Ageing effect on the field emission reproducibility of multiwalled carbon nanotubes

The ageing effect on the field emission (FE) reproducibility of multiwalleded carbon nanotubes (MWCNTs) synthesised by plasma enhanced chemical vapour deposition was investigated by scanning electron microscopy. To investigate the ageing effect on the physical state of the MWCNTs, a scanning electron microscope (SEM), a Raman spectrometer, an X-ray photoelectron spectroscope and an X-ray diffractometer were used to characterise the MWCNTs comprehensively before and after the ageing. Through ageing, the FE reproducibility became better because the larger number and more evenly distributed shorter MWCNTs – (resulted from the local vacuum breakdown of higher MWCNTs due to Joule heating and oxidisation) – became the dominating emitters.     

Nanocomposite three-dimensional solar cells obtained by chemical spray deposition

The present study is focused on low-cost preparation of thin film TiO2/CuInS2 nanocomposite three-dimensional (3D) solar cells. With the aid of a simple spray deposition method, we have been able to obtain 3D solar cells, with a remarkable energy conversion efficiency of 5%. The new 3D solar cell design has the potential to breakdown the price barrier and to open up new production technologies for low-cost photovoltaic solar cells.     

Engineering Multiwalled Carbon Nanotubes Inside a Transmission Electron Microscope Using Nanorobotic Manipulation

This paper provides a review of recent experimental techniques developed for shell engineering individual multiwalled carbon nanotubes (MWNTs). Basic processes for the nanorobotic manipulation of MWNTs inside a transmission electron microscope are investigated. MWNTs, bamboo-structured carbon nanotubes (CNTs), Cu-filled CNTs, and CNTs with quantum dots attached are used as test structures for manipulation. Picking is realized using van der Waals forces, “sticky” probes, electron-beam-induced deposition, and electric breakdown. Cap opening and shell shortening are presented using field emission current. Controlled peeling and thinning of the shells of MWNTs are achieved by electric breakdown, and changes in MWNT structures are correlated with electrical measurements. These processes are fundamental for the characterization of nanoscale materials, the structuring of nanosized building blocks, and the prototyping of nanoelectromechanical systems.      

Atomic layer deposition ultra-barriers for electronic applications-strategies and implementation

We show that Al2O3 thin films, grown by atomic layer deposition (ALD) on polyester, are ultrabarriers with moisture permeation <10(-5) g-H2O/m2-day, as determined after aging for more than three years. We present evidence that the mechanism for gas permeation in ALD Al2O3 films is not due to pinholes, but that the onset of permeation occurs abruptly, analogous to electrical breakdown in oxide thin films. We show that the permeation onset time increases for thicker Al2O3 films and higher ALD process temperature, for which the hydrogen defect concentration in Al2O3 films is less. Further, we show that mild plasma treatment of the polyester, prior to ALD deposition of Al2O3, makes the surface more hydrophilic and reduces moisture permeation compared to an untreated surface. Similarly, ALD deposition on the bare or non-slip side of the polyester film is preferred for low permeation.     

Suppression of electrical breakdown in silicon nitride films deposited by catalytic chemical vapor deposition at temperatures below 200 degrees C

Silicon nitride (SiN(x)) films for a gate dielectric layer of thin film transistors were deposited by catalytic chemical vapor deposition at a low temperature (< or = 200 degrees C). A mixture of SiH4, NH3 and H2 was used as a source gas. Metal-insulator-semiconductor (MIS) capacitor structures were fabricated for current-voltage (I-V) and capacitance-voltage (C-V) measurements. The breakdown voltage characteristics of the SiN(x) films were improved by the increase of NH3/SiH4 and H2/SiH4 mixing ratios and substrate temperatures. H2 treatment was attempted to improve the breakdown voltage further. A breakdown voltage as high as 6.6 MV/cm was obtained after H2 annealing at 180 degrees C. The defect states inside the SiN(x) films were analyzed by photoluminescence spectra. Silicon dangling bonds (2.5 eV) and nitrogen dangling bonds (3.1 eV) were observed. These defect states inside the SiN(x) films disappeared after H2 annealing. Flat band voltage shifts were observed in C-V curves, and their magnitudes decreased as the defect states inside the SiN(x) films decreased.     

Characteristics of monopole antenna plasmas for TEOS PECVD

Silicon dioxide film was deposited on Si substrate by plasma-enhanced chemical vapor deposition using a monopole antenna plasma source. Electron density was measured by a plasma absorption probe with and without a grounded plate close to monopole antennas. A high electron density was obtained with the grounded plate. The typical electron density of the monopole antenna plasma source was ∼ 3 × 10¹⁰ cm^− 3 at a position of 13 mm away from the antenna in oxygen plasma. The electron density rapidly decreased along the distance from the monopole antenna. Since the deposition rate and breakdown field were improved with the higher electron density, the grounded plate improved the performance of the SiO₂ film deposition.