Conventional Thermal Oxidation Research Articles

Mobile ion effects in low-temperature silicon oxides

Mobile ions in oxides formed on silicon by low-temperature processes have been studied using a combination of bias-temperature stress and triangular voltage sweep experiments. It is found that these oxides contain intrinsically low concentrations of mobile ions (<1010 cm−2) and that the ionic instabilities which are seen are due to alkali metal ions rather than other contaminants or the inherent water and hydrogen. Mobile sodium behaves slightly differently in low-temperature oxides compared with conventional thermal oxides, and can be gettered and passivated using a low-temperature process. It is shown that sodium ions are trapped by polycrystalline silicon during plasma hydrogenation, and that atomic hydrogen is involved in this process. The trapped ions are released back into the oxide during subsequent bias-temperature stressing.

Device applications of vanadium-doped silicon-dioxide

This study has been undertaken in an attempt to investigate the possible applications of transition-metal-doped amorphous silicon-dioxide in floating-gate avalanche-metal/silicon-dioxide/silicon-type nonvolatile memories, with the objective of developing an electrically erasable programmable read-only memory structure with low WRITE and ERASE voltages, (e.g., ≂5 V) which does not depend for its operation on the very thin tunneling oxides (i.e., ≤80 Å) currently used and which are a major source of device instability and degradation. Results are presented for 200-Å-thick vanadium-doped silicon-dioxide films which show reproducible current-voltage characteristics at much reduced voltages compared with conventional thin thermal oxides.

Improved radiation hardness of MOS devices with ultrathin nitrided oxide gate dielectrics prepared by rapid thermal processing

The radiation hardness of MOS devices with ultrathin nitrided oxides ( approximately 100 AA) prepared by rapid thermal nitridation (RTD) of thin oxides has been studied. The radiation was performed by exposing devices under X-rays of 50 keV to a dose of 0.5 Mrad(Si). Compared with conventional thermal oxides, the RTN oxide devices exhibit a much smaller increase in both the fixed charge N/sub f/ and the interface state D/sub it/ densities. In addition, it is found that higher RTN temperature and/or longer durations produce smaller Delta N/sub f/ and Delta D/sub it/. >

The effect of discharge conditions on the inductively coupled plasma oxidation of silicon

Plasma oxidation of silicon offers advantages over conventional thermal oxidation in that it is a low temperature (<500°C) method of thin film production which takes place in a clean vacuum environment. The growth rate and also the electrical properties of the oxides are a strong function of the plasma input power, pressure and system geometry. In this paper the effect of these discharge conditions on oxide growth rate, electrical breakdown strength and oxide interface charge levels is presented. By optimisation of the discharge conditions and by suitable temperature annealing, device quality oxides have been produced which have oxide interface charge levels in the range 10 10–10 11 cm 2 and electrical breakdown strengths in excess of 10 MV cm −1.

Low temperature oxidation of silicon

Oxidation of silicon in dry oxygen ambient at temperatures between 25°C to 500°C, with a point-to-plane corona discharge is studied. The oxidation rate for this case is a strong function of temperature and is found to increase significantly in comparison to the conventional thermal oxidation rate. For the thicker films, refractive index of the grown oxide layer approaches the value obtained for high-temperature thermally grown oxide.

High pressure dry oxidation kinetics of silicon—evidence of a highly stressed SiO2 structure

The kinetics of monocrystalline silicon oxidation using dry oxygen have been investigated over a wide range of pressure (14&amp;lt;P&amp;lt;1000 bars) within a low-temperature domain (600&amp;lt;T &amp;lt;780 °C). In this unexplored domain, the linear and parabolic rate constants are dependent on the pressure as B/A∼P0.7 and B∼P. The activation energy of B/A (1.70 eV) is lower than the experimental values observed in conventional thermal oxidation. Very high residual stress values have been found for these oxides together with high values of refractive index suggesting that the oxidation proceeded under compressive in-grown stresses.

Photoelectronic properties of hydrogenated amorphous silicon/silicon oxide heterostructures

A glow-discharge hydrogenated amorphous silicon/insulator heterostructure has been characterized by a range of measurements including optical absorption, temperature dependence of photo- and dark conductivity, internal photoemission, xerographic discharge, and spectral dependence of photoconductivity. Efficient injection of dark and photocarriers from amorphous hydrogenated silicon into, and transport through, relatively thick SiOx:N:H has been achieved. Unlike the conventional thermal oxide on Si, no significant energy barrier to injection is found in the plasma-deposited heterostructure. The use of the structure as a potential xerographic device is demonstrated. A mobility lifetime product as high as 6×10−10 cm2/V and a transport process with an activation energy of ∼0.3 eV is found for electrons in the SiOx:N:H films.

Piiotoelectronic Proiioerties Of Amorpiious Silicon/Silicon Oxide Heterostructures

A glow-discharge deposited a-Si:H/insulator heterostructu re has been characterized by a range of measurements including optical absorption, internal photoemission, xerographic discharge and spectral dependence of photoconductivity. Efficient injection of photocarriers from a-Si:H into, and transport through, films of SiOx:N:H up to 10 μm thick has been achieved. Unlike the conventional thermal oxide on Si, no significant energy barrier to injection is fotInd in the plasma deposited heterostructure. The use of the structure as a potential xerographic device is demonstrated. A mobility lifetime product as high as 6 x 10-10 cm2/volt is found for electronsin the SiOx:N:H.

The metal-insulator-semiconductor-switch (MISS) device using thermal nitride film as the tunneling insulator

Silicon thermal nitride films grown by using direct thermal nitridation of silicon have been used as a tunneling insulator in the metal-insulator-semiconductor-switch (MISS) device. This paper has shown that better uniformity and controllability of the MISS characteristics can be easily obtained by using thermal nitride film as a tunneling insulator when compared to those using conventional thermal oxide film. The superior merits of using silicon thermal nitride film are mainly due to the fact that direct thermal nitridation of silicon in ammonia gas exhibits much lower growth rate and unique self-limiting growth. Moreover, the higher structure density of the as-grown thermal nitride film may provide higher endurance for the MISS device in integrated-circuit applications. In addition, the MISS devices operated at lower voltage (< 5 V) have been fabricated and their characteristics are discussed.

Role of polymer morphology in the oxidation of polypropylene

AbstractThe γ‐initiated oxidation and presensitized photooxidation of polypropylene films and fibers are shown to be insensitive to sample thickness (if &lt;150 μm) and a range of morphological parameters such as molecular orientation (in drawn samples) and fibrillar and void content. The relevance of these observations is discussed in the light of the many previous assertions as to the influence of morphological effects on oxidation rates. The γ‐initiated oxidation was studied in preference to conventional thermal or photoinitiated oxidation because of the greater control over the rate of radical production available by this method.

Determining the Energy Distribution of Pulse-Radiation-Induced Charge in MOS Structures from Rapid Annealing Measurements

Activation energy distributions for the positive space charge induced in MOS structures by pulsed ionizing radiation have been calculated from shortterm, isothermal annealing data. These distributions are compared for conventional thermal oxides and oxides implanted with aluminum or sodium ions.