Metal Oxide Semiconductor Diodes Research Articles

Thermal behavior of deep levels correlated with iron in silicon metal-oxide-semiconductor structure

Thermal behavior of deep levels correlated with iron in Si MOS (metal-oxide-semiconductor) structure has been studied by isothermal capacitance transient spectroscopy. As a result, it is shown that interstitial iron scarcely affects the interface trap (Nt) of MOS structure. This is made clear by measuring Nt of Si MOS diodes containing iron impurity, the interstitial component of which is controlled by low temperature annealings. In addition, the low temperature (400 °C) annealing decreases interstitial iron concentration as well as interface trap density. This phenomenon is very lucky for Si MOS devices.

Metal‐Oxide‐Semiconductor Capacitance Measurements on Amorphous Silicon

A special metal oxide semiconductor (MOS) diode is built with amorphous silicon (a‐Si:H) as the semiconductor. The process is carried out so that the a‐Si is not subject to high temperatures. This allows the characterization of solar grade a‐Si:H by MOS diagnostic methods. Two types of structures (blanket a‐Si layers as well as reactive ion etched a‐Si mesas) are produced. Based on C‐V and C(ω) measurements an equivalent network is established which includes the effects of the majority carrier dissipation time constant, of the space‐charge punch‐through in depletion and inversion, and of lateral current flows. The network is checked at selected bias and frequency conditions using given geometrical and material data. When applied to accumulation, it delivers the layer resistivity and net carrier density.

Characterization of silicon surface microroughness and tunneling transport through ultrathin gate oxide

The surface morphology of chemically cleaned Si(100) surfaces has been studied by Fourier-transform infrared–attenuated total reflection (ATR) and atomic force microscopy (AFM). It is shown that the final cleaning in 0.1%HF+1%H2O2 after modified SC-1 clean yields a sharp SiH2 vibrational peak with weak SiH3 and SiH absorption bands while 4.5%HF treatment gives the twin peaks consisting of SiH2 and SiH3 absorptions. In contrast to this the AFM images exhibit no significant changes for the surfaces with significantly different ATR spectra. Quantitative analysis of the measured tunneling current for metal–oxide–semiconductor diodes fabricated on (100) surfaces with different surface morphologies has shown that the observed current is well fitted to the theoretically predicted characteristics.

Sodium contamination free ashing process using O2+H2O plasma downstream

The effect of O2+H2O plasma downstream ashing on sodium contamination from resists has been studied through measurement of flatband voltage shifts of metal–oxide–semiconductor (MOS) diodes after bias-stress treatment and measurement by atomic absorption spectroscopy of the amount of sodium in the SiO2 layer after resist stripping. The flatband voltage shift of the MOS diodes on which a resist layer was stripped by the O2+H2O plasma downstream was almost the same as that treated by the O2+H2O plasma downstream without resist and smaller than that where the resist was removed by other dry ashing methods such as O2 plasma and O2 plasma downstream. In addition, the amount of sodium that existed in the SiO2 layer after resist ashing by the O2+H2O plasma downstream was also nearly the same as that in the SiO2 layer as grown. This sodium passivation by the O2+H2O plasma downstream was most effective at the H2O percentage of 40%–60%, and did not depend on wafer temperature below 200 °C or over-ashing time. These results support our original idea of sodium passivation, i.e., OH radicals generated in the O2+H2O plasma and its downstream react with sodium to prevent sodium invasion into the SiO2layer.

Influence of Organic Impurities in Hydrogen Peroxide for Advanced Wet Chemical Processing

An improved high purity hydrogen peroxide was developed for advanced semiconductor devices manufacturing. After treatment of a Si wafer with this hydrogen peroxide, no metallic impurity was adsorbed onto the Si wafer surface. However, a few parts per million of organic impurities remain in the hydrogen peroxide as total organic carbon (TOC). These organic impurities result from the production process for raw hydrogen peroxide and are identified as formic acid, acetic acid, and cyclohexanone deviatives. To examine the influence of organic impurities on semiconductor devices, we evaluated the electrical characteristics of metal oxide semiconductor (MOS) diodes with thermal oxide films, including chemical oxide by treatment with the improved hydrogen peroxide. In spite of high organic impurity content, the experimental results show that the organic impurities in the hydrogen peroxide did not affect the properties of MOS diodes with about 9 nm oxide films.

Comparison of Lifetime Measurements from the Zerbst and the Dispersion Techniques

The admittance of metal oxide semiconductor (MOS) diode after switching from inversion to deep depletion is calculated. Special attention is given to the final stationary state in inversion conditions. For this state the relaxation equations must be modified because the usually assumed large signal carrier deficits are not valid. The results of these dispersion measurements are compared with the conventional Zerbst technique. Good agreement is obtained. The dispersion technique is a valuable tool for determining very short lifetimes.

Evaluation of Radiation Damage on Electrical Characteristics of SiO2 due to Reactive Ion Etching

Electrical characteristics of SiO2 are degraded due to reactive ion etching (RIE) radiation damage. We prepared metal-oxide-semiconductor (MOS) diode samples with plasma-exposed SiO2 film. Degradation of MOS diode characteristics was examined under several plasma conditions. Initial C-V measurement and B-T aging test show the RF power dependence of the radiation damage. The Vth shift increases with RF power. The Vth shift depends not on the plasma exposure time, but on the residual oxide thickness after plasma exposure. According to I-V measurement, trapped negative charge density increases with increasing RF power. The depth of the trapped charge centroid is proportional to Vdc1/2. Neutral and charged traps are generated in SiO2 due to ion bombardment.

Experimental Evidence for Anion Selective Behavior of Ion Beam Sputtered Film of Alkali Metal‐Free Phosphate Glass Deposited on MOS‐Diode

Selective adsorption of an anionic species on an alkali metal‐free lead phosphate glass membrane on a metal oxide semiconductor (MOS) diode was studied using capacitance‐voltage curves and electron spectroscopy for chemical analysis (ESCA) measurements. The phosphate glass‐coated MOS diode shows a linear relationship between the anion concentration and the relative capacitance change. The oxygen binding energy in the phosphate glass as determined by ESCA spectra shows two types of peaks 23.85 and 26.56 eV. It can be concluded that the anionic species can adsorb preferably on the lower surface anionic site and that the anion selective characteristics originate from the MOS diode surface.

Emission characteristics of metal–oxide–semiconductor electron tunneling cathode

We have fabricated a metal–oxide–semiconductor (MOS) electron tunneling cathode with ultrathin SiO2 and examined the emission characteristics. We found that the emission occurred from an entire gate area by electron tunneling through the potential barrier in the MOS diode and the emission current was 0.7% of the total current flowing through the diode. The emission was also found to be nearly independent of pressure.

Injection current model of a MOS diode under charge-sharing mode readout operation

Based on the Shockley diffusion theory, an injection current model for the metal-oxide-semiconductor (MOS) charge injection device (CID) under charge-sharing mode readout scheme is proposed. It is found that the relation of the injection current and the surface potential follows the ideal diode equation. A photocurrent method is developed to verify the model and the extracted ideality factor is very close to unity. An equivalent SPICE model of the MOS diode is derived and the simulated transient readout response fits the experimental data quite well.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Electrical properties of MOS and MIS diodes using an electrochemically prepared poly(N‐methylpyrrole)

AbstractOrganic semiconductor devices using electrochemically prepared poly(N‐methylpyrrole) (PNP) were characterized by capacitance‐voltage (C‐V) measurements. A device with aluminum evaporated on the PNP behaved as a MOS (metal‐oxide semiconductor) diode in vacuum. Assuming the oxide layer between the metal and the PNP to be pure Al2O3, the MOS parameters were calculated. The values obtained for depletion width W = 166 Å and acceptor density NA = 1018 cm−3 in the PNP were reasonable by comparison with the previously reported values obtained by Schottky analysis. An indium/poly(p‐phenylene)‐1,3,4‐oxadiazole (POD)/PNP diode was prepared, and C‐V measurements were carried out in air. The diode behaved like an MIS (metal‐insulator semiconductor) device, but the characteristics showed large variation with frequency. We have proposed a schematic model for this mechanism on the basis of the results obtained by dielectric measurements of POD and the temperature dependence of the MIS characteristics.

Summary Abstract: A hydrogen plasma diagnostic based on Pd metal–oxide–semiconductor diodes

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Temperature and energy dependences of capture cross sections at surface states in Si metal-oxide-semiconductor diodes measured by deep level transient spectroscopy

A new deep level transient spectroscopy technique is presented to determine capture cross sections at metal-oxide semiconductor (MOS) surface states. The technique enables us to determine energy and temperature dependences of capture cross sections separately. Applying this method, electron capture cross sections at surface states in Si MOS diodes were measured and found to have strong energy dependence and rather weak temperature dependence. It was also found that there was an effect to increase the emission rate, which may be attributed to barrier lowering at the Si-SiO2 interface.

Capacitance-voltage characteristics of Al/Al2O3/p-GaAs metal-oxide-semiconductor diodes

Metal-oxide-semiconductor (MOS) diodes were constructed on p-type GaAs by means of anodic oxidation of aluminum film evaporated on GaAs. By terminating the oxidation precisely at the Al-GaAs interface, MOS diodes in which the capacitance at low frequency increases in the positive-bias region were obtained. The interface state density determined by using the Terman method based on 1-MHz measurement of the C-V characteristics is on the order of 1010 cm−2 eV−1.

Comparison of the Behaviour of Metal-oxide Semiconductor Diodes using Different Semiconductor Materials†

ABSTRACT The theoretical behaviour of metal-oxide semiconductor diodes is analysed as a function of the semiconductor parameters. Indium arsenide, silicon. gallium arsenide and cadmium sulphide are considered. The capacitance-voltage and d.c. space charge-surface potential curves obtained by varying the bias on the metal electrode are plotted for the different materials with carrier concentration and oxide thickness as running parameters.