No abstract

We investigated the degradation of device reliability due to Negative Bias Temperature Instability (NBTI) of PMOSFET with ultrathin gate oxide. It was experimentally demonstrated that the chemical reactions at the gate oxide/substrate interface and/or diffusion of hydrogen related species are the major cause of the NBTI. We also found that nitridation of gate oxide enhances NBTI. In order to suppress the NBTI, the density of hydrogen terminated silicon bond at the interface needs to be minimized. Thus, the concentration of nitrogen in thin gate oxide has to be optimized in terms of the reliability reduction due to NBTI. IntroductionThe thickness of the gate oxide is aggressively reduced to achieve high speed and low power circuit operation at the same time. To meet this requirement, the electric field applied to the gate oxide increases as shown in figure 1. As reported recently [ 1-31, NBTI has become a major concem when realizing highly reliable integrated CMOS devices, because the Vth shift of the PMOSFET due to NBTI has become a limiting factor for MOSFET scaling [Z].On the other hand, nitridation technology is widely used to prevent boron penetration from p+ gate electrode. However, we found that nitridation of gate oxide degrades reliability of PMOSFET due to NBTI. In this paper, we show the origin of NBTI and the lnfluence of nitrogen incorporation. A possible mechanism for NBTI is proposed.

No abstract

This paper discusses how positive emotions can help maintain and improve mental health during the COVID-19 outbreak, taking into account examples of social interaction and positive psychology research efforts in Japanese context.

The integrated responses to gustatory stimuli applied to the soft palate were recorded from the greater superficial petrosal nerve (GSP) and were compared with those from the chorda tympani nerve (CT) innervating the anterior part of the tongue in the rat. Stimuli included various concentrations of NaCl, sucrose, HCl and quinine hydrochloride, and 0.5 M of six sugars. The inhibitory effects of amiloride on the responses to sodium salts, including various concentration of NaCl, 0.1 M sodium acetate and 0.01 M sodium saccharin, were also tested. Both the phasic and tonic responses to sugars in the GSP were significantly larger than those in the CT, whereas both responses to NaCl in the GSP were significantly smaller than those in the CT. Although amiloride at 50 microM significantly depressed the phasic and tonic responses to NaCl with a wide range of concentration in the CT, little inhibitory effect was observed in the GSP. The tonic response to sodium acetate, when dissolved in amiloride solution, was depressed to 15% of the control in the CT, and slightly but significantly depressed to 70% in the GSP. These response characteristics of the GSP may play important roles in the processing of gustatory information.

No abstract

No abstract

The objects of this study were to examine the change of the fine structure in isotactic polypropylene during isothermal crystallization and to determine whether the theory of molecular weight fractionation induced by crystallization or the lamellae thickening, due t o longitudinal translation or sliding diffusion of polymer chains in a crystal state (sliding diffusion theory) is important in the crystallization process. As crystallization proceeds, low melting crystals are produced, irrespective of molecular weight and molecular weight distribution. For high molecular weight polymers, the peak of the thermogram shifts t o higher temperatures, and the high melting components are produced mainly by the sliding diffusion mechanism. If the difference between the molecular weights of both components in a polymer blend is not too great, a peak is found in the DSC thermogram of such a crystallized blend which occurs roughly midway between those of each separately component crystallized under the same conditions as the blend. If the molecular weights of the two components differ greatly the DSC thermograms of the blend show that each component tends to crystallize separately. The experimental evidences, obtained by KAWAI, HOSOI, and KAMIDE in the case of linear polyethylene, against the fractionation theory are examined in detail for isotactic polypropylene. ZUSAMMENFASSUNG:Gegenstand dieser Arbeit war die Untersuchung der Anderung der Feinstruktur von isotaktischem Polypropylen wahrend der isothermen Kristallisation und die Feststellung, ob die Theorie der durch die Kristallisation induzierten Molekularfraktionierung oder die der durch die Translationsdiffusion der Polymerkette im Kristallzustand hervorgerufenen Lamellenverdichtung (Translationsdiffusionstheorie) bei dem KristallisationsprozeB die entscheidende Rolle spielt. Mit fortschreitender Kristallisation entstehen unabhangig vom Molekulargewicht und der Molekulargewichtsverteilung bei niedriger Temperatur schmelzende Kristalle. Bei Polymeren mit hohem Molekulargewicht wird das Maximum der Warmekapazitat zu hoheren Temperaturen hin verschoben ; die hoch schmelzenden Komponenten entstehen im wesentlichen uber den Translationsdiffusionsmechanismus. Sofern der Unterschied der Molekulargewichte zweier Komponenten einer Polymermischung nicht zu grog ist, findet man im DSC-Thermogramm einer solchen auskristallisierten Mischung ein Maximum, das in erster Naherung in der Mitte zwischen den Maxima der unter den gleichen Bedingungen wie die Mischung auskristallisierten getrennten Komponenten liegt. Sofern sich die Molekulargewichte der beiden Komponenten wesentlich unterscheiden, zeigt das DSC-Thermogramm der Mischung, dal3 beide Komponenten die Tendenz getrennt zu kristallisieren aufweisen. Die von KAWAI, HOSOI und KAMIDE fur lmeares Polyathylen auf experimentellem Wege erhaltenen Hinweise gegen die Fraktionierungstheorie werden am Beispiel des isotaktischen Polypropylens im Detail untersucht.