Hydrogen Concentration In Films Research Articles

Synthesis and characterization of helium-charged titanium hydride films deposited by direct current magnetron sputtering with mixed gas

Controllable helium-containing TiH2 phase films were prepared on Si (100) substances by magnetron sputtering with hydrogen-helium-argon mixed gas, in order to investigate the helium behavior in titanium tritide. The TiHxHe films were characterized by ion beam analysis (IBA) in which elastic recoil detection (ERD) and Rutherford backscattering spectrometry (RBS) methods are included, X-ray diffraction (XRD) and scanning electron microscope (SEM). It is found that with the increase in the relative hydrogen flow rate (QH: QAr) under the fixed helium flow and sputtering pressure, the hydrogen concentration in TiHxHe films increases at first, and then decreases. Though the hydrogen concentration in TiHxHe films can be greatly increased by increasing the total sputtering pressure, excessive sputtering pressure will deteriorate the crystallization quality. Although the helium concentration mainly relies on the relative helium flow rate of mixed gas during sputtering, the increase of the relative helium flow rate will reduce the concentration of hydrogen in films at fixed sputtering pressure dramatically. Fortunately, suitable relative hydrogen flow and sputtering pressure can maintain a high concentration of hydrogen in the films. Thus TiHxHe films with controllable hydrogen and helium content can be achieved.

水素吸蔵合金ＬａＮｉ５の薄膜アクチュエータのパラジウム表面処理による高応答性

In this study, the effect of the palladium surface treatment was investigated on the mechanical response of the LaNi5 thin film actuator deposited on polyimide substrates. Since controlling the hydrogen concentration in film by changing the pressure may reversibly drive this actuator, this film actuator can be expected as a sensor and/or a controller of hydrogen gas flux in various hydrogen-related devices. In the present experiments, it was shown that the initiating time for the actuation to be measured after hydrogen gas exposure was reduced from 100 s to 1 s by the palladium surface treatment. This significantly improved mechanical response was attributed to the switching of the reactions in the rate determining steps. The rate determining reaction after the palladium treatment was no longer the dissociation of hydrogen gas molecules on the sample surface, but the hydrogen permeation or diffusion in the film. Furthermore, it was found that the high responsiveness induced by the palladium treatment was also caused by the high permeability of hydrogen in palladium film at room temperature.

Plasma-enhanced CVD of organosilicate glass (OSG) films deposited from octamethyltrisiloxane, bis(trimethylsiloxy)methylsilane, and 1,1,3,3-tetramethyldisiloxane

Octamethyltrisiloxane (OMTS), bis(trimethylsiloxy)methylsilane (BTMS), or 1,1,3,3-tetramethyldisiloxane (TMDS) mixed with oxygen and argon produced organosilicate glass (OSG) films having high methyl content under pulse plasma-enhanced chemical vapor deposition (PECVD). The hydrogen concentration in films deposited from OMTS, BTMS, and TMDS can exceed twice the maximum concentration in films grown from methylsilane precursors. However, the refractive indices and dielectric constants of the films grown from OMTS, BTMS, and TMDS were close to that of minimum values observed for the films grown from methylsilane precursors. This suggests that at high concentrations, methyl incorporation does not result in further reduction of film density. 29Si nuclear magnetic resonance (NMR) resolves the complex differences in the structure of the OSG films that are not apparent from Fourier transform infrared spectroscopy (FTIR) and reveals that the stability of OSG materials is improved by eliminating M groups and favoring the incorporation of T groups. These films exhibit low dielectric constants in the range of 2.4–2.6.

Hydrogen-induced breakdown of low-temperature molecular-beam epitaxy of Si.

Low-temperature molecular-beam epitaxy of Si is characterized by the existence of an epitaxial thickness ${\mathit{h}}_{\mathrm{epi}}$, below which the film is epitaxial and above which the film turns amorphous. Epitaxial films with a thickness beyond ${\mathit{h}}_{\mathrm{epi}}$ can be grown, provided a rapid-thermal-anneal (RTA) step to a sufficient temperature, ${\mathit{T}}_{\mathrm{RTA}}$, is executed before reaching ${\mathit{h}}_{\mathrm{epi}}$. Positron-annihilation spectroscopy shows that ${\mathit{T}}_{\mathrm{RTA}}$=450 \ifmmode^\circ\else\textdegree\fi{}C is not sufficient but 500 \ifmmode^\circ\else\textdegree\fi{}C is. We explain this cutoff in RTA temperature using a model based on Si-H bond breaking. Nuclear reactions analysis support this model and show a high concentration of hydrogen in films grown with RTA below 450 \ifmmode^\circ\else\textdegree\fi{}C. According to the proposed model, a reduction of the hydrogen content in the growth ambient should lead to larger ${\mathit{h}}_{\mathrm{epi}}$.

Hydrogenated amorphous silicon: Hydrogen content, bonding configurations and morphology in sputter-deposited, in-chamber annealed thin films

The infrared absorption features of sputter-deposited amorphous silicon (a-Si:H) thin films prepared under different substrate temperatures ( T s) and an in-chamber annealing treatment were analysed as a function of anneling temperatures ranging from 200 to 600°C. Fourier-transform infrared absorption spectroscopy and scanning electron microscopy were used to analyse the evolution of film characteristics after annealing. Hydrogen bonding configurations for higher T s, in-chamber annealed samples showed a higher proportion of monohydride grouping, and further annealing steps revealed that hydrogen is much more tightly bonded under these deposition conditions than when T s is lower and the in-chamber annealing treatment not used. Oxygen and nitrogen contamination, both during and after deposition, have also been found to be reduced when samples were in-chamber annealed. Samples deposited at low T s and not in-chamber annealed showed the same surface damage as samples prepared at higher T s and which were then annealed at temperatures starting at 300°C, indicating a high degree of stress, probably caused by an excessive hydrogen concentration in films prepared at lower T s.

The Combined Effect of Hydrogen and Oxygen Impurities in the Silicon Nitride Film of MNOS Devices

The combined effect of varying the hydrogen and oxygen impurities in the silicon nitride film of metal‐nitride‐oxide‐semiconductor (MNOS) devices was studied to develop a correlation among the chemical composition, current conduction, charge trapping, and memory properties of the devices. The atomic percentage of hydrogen increased in the film as a function of decreasing deposition temperature from 850 to 650°C. Oxygen was incorporated into the film by replacing nitrogen atoms through the use of nitrous oxide gas during the film deposition process. The addition of oxygen further reduced the hydrogen concentration in the film. The trapped electron and hole densities decreased by 25 and 66%, respectively, with a corresponding decrease in film conductivity as hydrogen and oxygen concentration in the silicon nitride film increased by 4 and 12%, respectiyely. The incorporation of hydrogen and oxygen improved the overall average device retention and endurance characteristics by 40% and from 107 to 108 cycles, respectively. The hydrogen and oxygen impurities may passivate the silicon dangling bonds associated with shallow traps within the bandgap of silicon nitride and, thus, allow the carriers to become trapped in deep traps, yielding enhanced memory properties in the MNOS devices.

High Quality Deposition of SiO2 Downstream from a Microwave Discharge

ABSTRACTHigh quality stoichiometric silicon dioxide films have been deposited on silicon substrates at low pressure(1.0Torr) and low temperatures(≤ 350C) downstream and at a right angle to a microwave discharge. The deposition was accomplished by injecting 2% SiH4 in helium downstream of a N20 microwave generated discharge. Infrared spectroscopic analysis has determined that no detectable SiH, SiOH, Si-H2o or SiN chemical complexes were present in any films deposited at temperatures above 250C. Rutherford Backscattering and Forward Scattering Detection Spectroscopy were used to determine the elemental composition and hydrogen concentration in the films, respectively. The thick films were found to be stoichiometric with no detectable elemental impurities. The measured hydrogen concentration in the thin films was comparable to that measured in thermally grown Si0 2 of approximately the same thickness. The quality of the thin oxides(<30nm) has been determined by fabricating MOS devices from the Si-Si0 2 system.