Ming-Jer Jeng

Thin-gate oxides prepared by pure water anodization followed by rapid thermal densification

Anodic oxidation at room temperature with pure deionized water as electrolyte and then followed by high-temperature rapid thermal densification was used to prepare high breakdown endurance thin-gate oxides with thicknesses of about 50 /spl Aring/. It was observed that the oxides prepared by anodic oxidation followed by rapid thermal densification (AOD) show better electrical characteristics than those grown by rapid thermal oxidation (RTO) only. The AOD oxides have a very low midgap interface trap density, Ditm, of smaller than 1/spl times/10/sup 10/ eV/sup -1/ cm/sup -2/ and negative effective oxide trapped charge. From the smaller leakage currents observed during staircase ramp voltage time-zero dielectric breakdown (TZDB) and constant field time-dependent dielectric breakdown (TDDB) testings, it is supposed that the uniform interfacial property and the pretrapped negative charges in AOD oxides are responsible for the improved characteristics.

Clockwise C-V hysteresis phenomena of metal--tantalum-oxide--silicon-oxide--silicon ( p) capacitors due to leakage current through tantalum oxide

Thermal tantalum oxide with a thickness of 620 A was studied. The dc leakage resistance and high‐frequency (1‐MHz) resistance of a metal–tantalum‐oxide–silicon capacitor were found to be on the order of 108 and 1 Ω cm2, respectively. The C‐V behavior of the capacitor, with its initial states being carefully treated, was reproduced and observed to be dependent on the return voltage and hold time (at return point) of the measurement conditions. And only negative charges were observed to be responsible for the conduction current through tantalum oxide. A model with the considerations of the ac equivalent circuit and low‐frequency leakage characteristic of tantalum oxide was proposed for these observations. Theoretical examples, with their parameters being suitably given according to the measured data, were shown, and they explained the experimental observations quite well. It is found that the measurement conditions and effect of the ac resistance of tantalum oxide on the determination of flat‐band capacitan...

Enhanced nitrogen incorporation and improved breakdown endurance in nitrided gate oxides prepared by anodic oxidation followed by rapid thermal nitridation in N2O

Room‐temperature anodic oxidation (ANO) followed by rapid thermal nitridation in N2O was used as new method to prepare thin nitrided oxides. It was found that the ANO nitrided oxides demonstrate better interfacial property and breakdown endurance than rapid thermal oxidation (RTO) nitrided oxides. The concentration of nitrogen incorporated in ANO nitrided oxide is larger than that in RTO nitrided oxides. It is believed that the loose density and the existence of hydrogen related species in anodic oxides formed by room‐temperature anodization cause nitrogen to diffuse easier into oxide and pile up at Si/SiO2 interface during N2O nitridation. In addition, the self‐readjustment of anodization current through the weak path in oxide is beneficial to thin gate oxides.

Fluorinated thin gate oxides prepared by room temperature deposition followed by furnace oxidation

Abstract Room temperature deposition in H 2 SiF 6 solution, i.e., liquid phase deposition (LPD), followed by furnace oxidation (FO) is first used to prepare fluorinated thin oxides (LPD/FO). The amount of fluorine existing in the gate oxide is controlled by varying the LPD time in this work. A turnaround breakdown behavior is observed for LPD/FO oxides with various LPD conditions. The oxide with an optimized fluorine concentration shows a significant improvement in oxide breakdown characteristics.

Rapid thermal postoxidation anneal engineering in thin gate oxides with Al gates

The effects of rapid thermal postoxidation annealing (POA) on the characteristics of thin gate oxides, /spl sim/10 nm, were systematically studied with respect to POA time, temperature and pressure. Two kinds of rapid thermal POA techniques were examined. One (POA1) was carried out by switching oxygen into nitrogen immediately after oxidation, while the other (POA2) was done by cooling down first and subsequently heating again in pure nitrogen. It was experimentally observed that the samples annealed by POA2 have larger charge-to-breakdown, Q/sub BD/, and lower interface trap density, D/sub itm/, than those annealed by POA1. But, the samples annealed by POA2 will result in poor immunity to radiation damage. In addition, it is also found that the samples with high POA temperature and low POA pressure treatments have large improvement in Q/sub BD/, but have serious degradation in the radiation hardness. A reoxidation technique after POA was used to improve the radiation hardness degraded by POA.

Preparation of low-temperature fluorinated oxides by anodic oxidation in dilute hydrofluosilicic acid (H2SiF6) solution

Anodic oxidation at room temperature in dilute H2SiF6 solution is proposed as a method to grow the low-temperature fluorinated oxides. It was found that two competing mechanisms exist in anodization. One is the growing mechanism due to constant current anodization and the other is the etching mechanism due to the existing HF solution. It was observed that fluorine atoms are incorporated into the anodic oxides. A growth rate of about 1 μm/h was found that is much higher than by liquid phase deposition (LPD) techinques reported nowadays. Also, the anodic oxides show less leakage current and higher breakdown field properties than the conventional LPD oxides. An excellent breakdown field strength of 10 MV/cm was found in this work.

Rapid thermal post-metallization annealing effect on thin gate oxides

Rapid thermal processing is used for post-metallization annealing (PMA) in this work. It was found that the rapid thermal PMA can do almost the same anneal work in the initial characteristics of MOS capacitors with an oxide thickness of 10 nm as the conventional furnace PMA. But the reliabilities in hot-carrier and radiation resistances of MOS capacitors depend on the PMA process significantly. It was found that rapid thermal PMA samples exhibit worse properties in hot-carrier resistance but better properties in radiation hardness than furnace PMA samples. For rapid thermal PMA process, the higher the annealing temperature, the stronger the initial annealing extent but the worse the hot-carrier and the radiation resistances.

Rapid Thermal Post-Metallization Annealing in Thin Gate Oxides

Rapid thermal technique was used in the post-metallization annealing (PMA) of thin gate oxide devices. A suitable choice of the rise rate, the setting temperature, and the hold time in the rapid thermal PMA (RTPMA) process is helpful to improve the oxide quality. It was found that the samples subjected to appropriate RTPMA conditions exhibit almost the same initial characteristic in flatband voltage V FB and midgap interface trap density D itm as those subjected to conventional furnace PMA (FPMA). However, the RTPMA samples exhibit longer time-to-breakdown t BD and higher time-zero-dielectric-breakdown (TZDB) field E BD than the FPMA ones. In addition to the known spiking effect caused by aluminum penetration into silicon, which seriously degrades the breakdown property, formation of aluminum oxide near the Al/SiO2 interface in the early stage and then aluminum silicon alloy in the later stage was proposed to explain the experimental observation.