Nitrided Oxide Films Research Articles

Nitrogen bonding, stability, and transport in AlON films on Si

The chemical environment of N in nitrided aluminum oxide films on Si(001) was investigated by angle-resolved x-ray photoelectron spectroscopy. Two different bonding configurations were identified, namely N–Al and N–O–Al, suggesting the formation of the AlN and AlO2N compounds. The near-surface region is N-rich and AlN compounds therein are more abundant than AlO2N, whereas in bulk regions the proportions of these two compounds are comparable. Rapid thermal annealing at 1000 °C for 10 s in vacuum or in low-pressure oxygen atmosphere led to the breakage of N–Al bonds in AlN, releasing N and Al. The mobile N is partly lost by desorption from the surface and partly fixed by reacting with the network to form AlO2N. The released Al atoms, which remain immobile, react with oxygen from the film or from the gas phase. Characterization of the films outermost surfaces by low-energy ion scattering revealed that the migration of Si atoms from the substrate across the films, reaching the surface and being oxidized therein, is not entirely inhibited in AlON/Si, although this migration is largely reduced as compared to nonnitrided Al2O3 films.

Electronic transport in amorphous carbon nitride (a-CN x:H) and carbon oxide (a-CO x:H) films

The dielectric properties of a-CN x :H and a-CO x :H thin films have been investigated using ohmic σ( T) and field-dependent σ( F) electrical conductivity measurements. A lower density of electronic states in carbon oxides has been inferred from the Ln( σ)≈ T −1/4 behavior, consistent with a hopping mechanism. The dielectric constant ε values deduced from the Poole–Frenkel field-dependence are found to decrease (increase) with increasing oxygen (nitrogen) content. Using refractive index values obtained from ellipsometry, a good agreement between ε and n 2 is found for the oxygen-rich (18–20%) alloys, having values of ε∼1.9–2.3, which could be considered as a new low dielectric constant material.

Thermal stability of plasma-nitrided aluminum oxide films on Si

The effect of post-deposition rapid thermal annealing in vacuum and in dry O2 on the stability of remote plasma-assisted nitrided aluminum oxide films on silicon is investigated. The areal densities of Al, O, N, and Si were determined by nuclear reaction analysis and their concentration versus depth distributions by narrow nuclear reaction resonance profiling, with subnanometric depth resolution. Annealing in both vacuum and O2 atmospheres produced partial loss of N from the near-surface regions of the films and its transport into near-interface regions of the Si substrate. Oxygen from the gas phase was incorporated in the AlON films in exchange for O and N previously existing therein, as well as in the near-interface regions of the Si substrate, leading to oxynitridation of the substrate. Al and Si remained essentially immobile under rapid thermal processing, confirming that the presence of nitrogen improves the thermal stability characteristics of the AlON/Si structures in comparison with non-nitrided Al2O3/Si.

Oxide-Nitride-Oxide막을 게이트 절연막으로 사용하여 제조한 다결정실리콘 박막트랜지스티의 특성

HTO(High Temperature Oxide) films are mainly used as a gate insulator for polysilicon thin film transistors(Poly-Si TFT's). The HTO films, however, show the demerits of a high leakage current and a low electric breakdown voltage comparing with conventional thermal oxides even though they have a better surface in roughness than the thermal oxides. In this paper, we propose an ONO(Oxide-Nitride-Oxide) multilayer as the gate insulator for poly-Si TFT's. The leakage current and electric breakdown voltage of the ONO and HTO were measured. The drain current variation of poly-Si TFT's with a variety of gate insulators was observed. The thickness optimization in ONO films was carried out by studying I<TEX>$\_$</TEX>on/I<TEX>$\_$</TEX>off/ ratio of the poly-Si TFT's as a function of the thickness of ONO film adopted as gate insulator.

Fabry–Pérot structures for attenuated phase-shifting mask application in ArF and F2 lithography

We demonstrate a structure for an attenuated phase-shifting mask (APSM) which is based on a three-layer Fabry–Pérot structure for ArF (193 nm) and F2 (157 nm) excimer laser based lithographies. The APSM structure is composed of a metal/dielectric/metal stack. The optical characteristics of the Fabry–Pérot structure meet the following requirements: 180° phase shift, transmittance in the range of 4%–15%, reflectance of less than 10% at the exposure wavelength, and high inspection contrast at the inspection wavelength. Common dielectric and metal materials, such as chromium, tungsten, amorphous silicon, silicon dioxide, aluminum oxide, and aluminum nitride films, can be used to construct the Fabry–Pérot structure. The top metal layer can also prevent charge accumulation during electron-beam writing.

Thin dielectric reliability assessment for DRAM technology with deep trench storage node

The reliability results of thin gate oxide and nitride–oxide film development for application in dynamic random access memories are presented. Data and observations from this technology development are embedded in general state-of-the-art review. Therein features of lifetime extrapolation models are discussed. Process and test structures as well as the stress procedure are briefly described. Among the data presented are long term stress results supporting the anode hole injection model down to 5 V, breakdown propagation results and the soft breakdown of 6 nm oxide, which allows detection of device degradation due to Fowler–Nordheim stress. Furthermore the dependence of the voltage acceleration on oxide thickness is shown for the range of less than 2–10 nm oxide thickness. The importance of physical failure analysis is emphazised.

Carbon-nanotube-based nonvolatile memory with oxide–nitride–oxide film and nanoscale channel

We have fabricated a single-wall carbon-nanotube (CNT)-based nonvolatile memory device using SiO2–Si3N4–SiO2 (ONO) layers as a storage node. The memory device is composed of a top gate structure with a channel width of a few nanometers and the ONO layer embedded between CNT and gate electrode. When the bias voltage between the CNT and gate electrode increases to 4 V, charges are tunneled out from CNT surfaces and captured to the traps in the ONO layers. Stored charges on the trap sites make the threshold voltage shift of 60 mV and is independent of charging time, suggesting that the ONO has traps with a quasiquantized energy state. The quantized state is related to the localized high electric field associated with CNT channel. The CNT-field-effect transistor with an ONO storage node could be used for an ultrahigh-density nonvolatile memory.

A model of radiation effects in nitride–oxide films for power MOSFET applications

Total dose effects in composite nitride–oxide (NO) films with various nitride and oxide thicknesses are studied. Metal nitride oxide semiconductor (MNOS) devices with thicknesses in the range of power transistors have been irradiated with X-rays up to a total dose of 1 Mrad (SiO 2). A model is proposed to describe the observed flatband voltage shifts as a function of total dose in the range of electric fields where the charge yield in the dielectrics to a first order approximation is linearly proportional to the electric field. The modulation of electric field in the dielectrics due to charge accumulation at the NO interface is found to be the dominating factor in determining the flatband voltage shift. It is suggested that, for the process conditions examined here, n-channel MNOS devices with oxide thickness between 12 and 15 nm give minimal radiation-induced flatband voltage shifts.

Combining Eels and Angle-Resolved Aes to Measure Shallow Profiles of Thin Nitrided Oxide Films on Si

Journal Article Combining Eels and Angle-Resolved Aes to Measure Shallow Profiles of Thin Nitrided Oxide Films on Si Get access J Bruley, J Bruley IBM Microelectronics Division, Hopewell Junction, NY Search for other works by this author on: Oxford Academic Google Scholar H Wildman, H Wildman IBM Microelectronics Division, Hopewell Junction, NY Search for other works by this author on: Oxford Academic Google Scholar A Paterson A Paterson IBM Microelectronics Division, Hopewell Junction, NY Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 8, Issue S02, 1 August 2002, Pages 596–597, https://doi.org/10.1017/S1431927602105927 Published: 01 August 2002

Measurement of the elastic and viscoelastic properties of dielectric films used in microelectronics

The Brillouin light scattering technique has been exploited in order to study the elastic properties of dielectric films used in microelectronics, such as silicon oxide, silicon oxinitride and silicon nitride films deposited on (1 0 0)-Si by different techniques. In the case of films as thick as approximately 0.4 μm, a number of Rayleigh–Sezawa modes, polarised in the sagittal plane were detected, as well as Love modes which have a shear horizontal polarisation. In addition, the longitudinal resonance corresponding to a longitudinal wave travelling parallel to the free surface was revealed. In thicker films (0.8–0.9 μm) we could also measure the longitudinal bulk mode, travelling at an angle with respect to the film normal. The mass density of the films was accurately measured by X-ray reflectivity. A best fit procedure of the calculated acoustic phase velocities on the measured ones enabled us to determine the elastic properties of the films and to put in evidence their dependence on the particular deposition technique and on the annealing treatment. The obtained values of the elastic constants were used to reproduce, using finite element calculations, the measured stress vs. temperature, achieving an estimation of both the thermal expansion coefficient and the viscosity of the films.

Paper-Like Display Utilizing Organic Electroluminescent Diodes Fabricated on 10 Micron-Thick Polyimide Films

ABSTRACTAn organic light emitting device (OLED) has been successfully fabricated on a thin paper-like polyimide substrate (about 10 μm-thick), which is sandwiched between silicone oxide and silicone nitride films. The emission characteristics of the OLEDs, which consist of diamine derivative (α-NPD) and 8-hydroxyquinoline aluminum (Alq3), are similar to those fabricated on a conventional glass substrate. Since the substrates and the OLEDs are very thin like a paper, the devices can be applicable for paper-like displays.

Abrupt current increase due to space-charge-limited conduction in thin nitride–oxide stacked dielectric system

In this article, the conduction mechanisms in nitride–oxide stacked structures on Si are investigated experimentally and theoretically. Amorphous silicon nitride films (3–5 nm thick) were deposited by low-pressure chemical vapor deposition. The ultrathin oxide layers (1–1.5 nm thick) were formed by reoxidization of the nitride layer at about 900 °C in wet ambient. The current–voltage characteristics for negative and positive gate polarities are asymmetric. An abrupt current increase under negative gate bias prior to dielectric breakdown is reported for this structure. This current–voltage phenomenon is attributed to trap-controlled single-carrier steady-state space-charge-limited conduction—the solid state analog of space-charge-limited current in a vacuum diode. Details of space-charge-limited conduction parameters depend on the thickness of the dielectric film and temperature. The study of those parameters can yield information about the traps inside nitride–oxide films. Such information can provide considerable insight into charge transport mechanisms and carrier trapping in these materials, which are important in understanding the physical processes involved in the basic film properties.

Growth of germanium quantum dots on different dielectric substrates by chemical-vapor deposition

The growth of Ge quantum dots on various nitrided oxides has been achieved by ultra-high-vacuum chemical-vapor deposition with GeH4 gas at temperatures between 550 and 650 °C. The characteristics of the Ge dots were investigated using atomic-force microscopy, Auger electron spectroscopy, and x-ray photoelectron spectroscopy in order to find the mechanism of the Ge dot formation. On N2O-annealed nitrided oxide films, we obtained Ge dots with height and diameters of 3.2 and 11 nm, respectively. No Ge dots were formed on surfaces of other dielectric substrates at 550 °C. From our experimental results, we suggest that the surface of N2O-annealed nitrided oxide contains a large amount of defects such as dangling bonds, which act as Ge nucleation sites. This is further confirmed by studying the growth kinetics and the influence of in situ annealing of the samples.

Structure of defects in silicon oxynitride films

Amorphous silicon oxynitride (a-SiNxOy) films were deposited at 300 °C using a plasma-enhanced chemical vapor deposition technique, which was carried out with variation in the nitrogen-flow-rate ratio (RN) and the oxygen-flow-rate ratio (RO) to control the nitrogen and oxygen contents, x and y, respectively. Changes in the structural properties and the characteristics of defects in the films were examined based on the electron spin resonance as well as infrared and optical absorption measurements. An increase in either RN or RO was found to decrease the deposition rate, the density of charged or neutral defects, and the randomness of the bonding network. Thus the incorporation of O or N atoms into Si nitride or Si oxide films, respectively, acts to improve the qualities of the insulating films. Furthermore, the nearest N and O atom neighboring to a Si site would be randomly bonded to the Si atom. Our results also showed that N-related dangling bonds, other than so-called K centers, are favorably created after annealing, but that the formation of Si–O bonds in the films makes the formation of such defects difficult.

Total dose effects in composite nitride-oxide films

Total dose effects in composite nitride-oxide (NO) films with nitride thicknesses from 58 nm to 183 nm and oxide thicknesses from 5 nm to 30 nm are studied. A model is proposed in order to relate the threshold-voltage shift to the NO thickness combinations. It is found that the electron-hole pairs generated in the bulk of the nitride do not contribute significantly to shifting the threshold-voltage. The NO films with 10 nm oxide show smaller threshold-voltage shift than composite films with any other oxide thicknesses.

Reactive deposition of nitrides and oxides using a twin-cathode inverted cylindrical magnetron

Nitrides and oxides of aluminum and other metals were reactively sputtered in a twin-cathode inverted cylindrical magnetron run with mid-frequency power. This geometry is particularly suited for coating three-dimensional objects of complex shape. However, high rate reactive sputtering in such an enclosed cathode has not been reported and presents unknown processing conditions. High rate deposition requires operation at a point that is normally unstable. For aluminum nitride films, high pumping speed was sufficient to ensure stable operation. Reactive deposition of oxides required feedback from the discharge current to control the flow of oxygen. This was successful for the relatively simple case of aluminum oxide, and the much more complicated case of titanium oxide. Films were deposited onto glass substrates under conditions of different pressure, power, and reactive gas flow. Reactive gas flows were found where good films of aluminum nitride and aluminum oxide could be deposited at high rates. Rates (relative to pure aluminum) were 32% for aluminum nitride and 26–40% for aluminum oxide. Both aluminum nitride and aluminum oxide films were insulating, non-absorbing, and adherent to the glass substrates.

Effects of the Final Oxidation Step on N and O Distributions in Silicon Oxide/Nitride/Oxide Ultrathin Films

Isotopic tracing was used to determine the distribution of O and N after the final fabrication step of ultrathin silicon oxide/nitride/oxide (ONO) films, revealing how the processing parameters affect the characteristics of the resulting structure. ONO films were prepared on precleaned Si wafers in three steps: (i) thermal oxidation in dry , at 1000°C in a rapid thermal processing furnace; (ii) remote plasma enhanced chemical vapor deposition of a nitrade layer in a mixture of and silane, and (iii) a second thermal oxidation step in a Joule‐effect heated furnace, in dry , at three different temperatures and for three different times. Nuclear reaction analysis and narrow nuclear resonance depth profiling with nanometric resolution were used to determine the distribution of , , and in the samples, before and after the reoxidation step. It is shown that the final structure is not a stacked one, but rather a silicon oxynitride ultrathin film with variable composition, presenting moderate concentrations of N in the near‐surface and near‐interface regions, and a higher N concentration in the bulk. Long treatments at high temperatures produce a significant loss and redistribution of N. © 1999 The Electrochemical Society. All rights reserved.

Growth and characterization of ultrathin nitrided silicon oxide films

This paper reviews recent progress in understanding microstructural and growth-mechanistic aspects of ultrathin (<4 nm) oxynitride films for gate dielectric applications. Different techniques for characterizing these films are summarized. We discuss several nitridation methods, including thermal (oxy)nitridation in NO, N2O, and N2 as well as a variety of deposition methods. We show that a basic understanding of the gas-phase and thin-film oxygen and nitrogen incorporation chemistries facilitates the processing of layered oxynitride nanostructures with desirable electrical properties.

Mechanism of low temperature nitridation of silicon oxide layers by nitrogen plasma generated by low energy electron impact

Thermal silicon oxide layers formed on the Si substrate can be nitrided at low temperatures ranging between 25 and 700 °C by nitrogen plasma generated by low energy electron impact. The nitrogen concentration is high near the oxide surface, and the nitrogen atomic concentration ratio [N/(Si+O+N)] at the surface ranges between ∼10% and ∼25%, depending on the nitridation conditions. For nitridation above 450 °C, only N≡Si3 (i.e., a nitrogen atom bound to three Si atoms) is observed in the nitrided oxide films by x-ray photoelectron spectroscopy measurements, while both N+=Si2 (i.e., an N+ ion bound to two Si atoms) and N≡Si3 are present with nitridation below 400 °C. When a negative bias voltage is applied to the Si with respect to the grid used for the generation of nitrogen plasma, the nitrogen concentration in the film increases, indicating that nitrogen cations play a dominant role in the nitridation. It is concluded that, first, N+ ions react with SiO2 to form N+=Si2, after which inward movement of N+ ions occurs with the assistance of an electrical field induced in the nitrided oxide layers by nitrogen ions at the surface. Ultimately, N+=Si2 is transformed to N≡Si3.

Structure and Bonding in Nitrided Oxide Films by Sims and Xps

ABSTRACTThe N distribution and bonding in five types of oxynitride films have been investigated using SIMS and XPS. Films were grown using N2O, NO-O2 and NH3 gas sources, a remote plasma N source and a Helicon plasma source. The SIMS measurements show different N distributions for each type of sample. XPS measurements show only N≡Si3 bonding in the gas source films, N≡Si3 and O-N-Si2 bonding in the remote plasma sample, and N≡Si3, O-N≡Si2, and O2≡N-Si bonding in the Helicon plasma sample. Angle-resolved XPS measurements show that the O2≡N-Si bonding is deepest in the sample whereas the O-N≡Si2 bonding is associated with a surface oxide.