Si MOSFET集積回路は,スケーリング則を微細化の指導原理として,高速化,高集積化を実現してきたが,最小寸法がサプミクロン以下になると,素子内部の高電界効果による素子破壊や劣化,あるいは,チップの配線抵抗増大や発熱密度の増大など深刻な問題が顕在化してくる.低温動作Si MOSFET集積回路は,これら問題の解決の展望を開くものである.本論文では,低温動作MOSFETの動作電圧,基板不純物濃度などの設計指針を与える温度スケーリング則ならびに温度・寸法合成スケーリング則,さらに77K動作0.1 μmチャネルMOSFETの設計について紹介する.
Si MOS ULSIにおける熱酸化膜の信頼性にかかわる事象のうちで最も大きな課題となる絶縁破壊が,酸化膜厚依存性をもち,清浄化で表面汚染を低減することにより, 10nm付近の膜厚領域で不良率が減少することを明らかにした.経時絶縁破壊に対する信頼性の向上のカギが,欠陥密度の低減と電界加速の抑制にあることを指摘し,欠陥の主たる原因がSi基板にあり,改善により信頼性が著しく向上することを示した.種々の製造プロセス中の欠陥原因について議論した.
The voltage-time characteristics of the corona onset and breakdown of (SF6/Ar) mixture gas, in a high-field composed by a small needle-plane gap, were investigated experimentally under various positive and negative rectangular pulses with wave fronts of microseconds. As in the case of pure Ar gas, the corona onset and breakdown voltages in (SF6/Ar) mixture containing a small amount of SF6 gas decreased with increase in the wave front. However, for further increase in the content of SF6 gas, the breakdown voltage increased with increasing wave front and reduced on further increase in the wave front. This particular V-t curve could be seen with a small amount of SF6 under a negative needle than positive. The polarity effect with higher voltages under a negative needle was also seen on both corona onset and breakdown in the needle-plane gap. These anomalous V-t curve of mixtures are compared with those obtained under sphere-plane gap and are discussed on the basis of prebreakdown corona characteristics.
A new carbon helical spring for use in high temperature and/or corrosive atmosphere has been developed by using carbon/carbon composite. The characteristics of the carbon spring were dependent on the property of the composite, diameter and pitch of the coil and its turning number and obeyed Hooke's Law within a certain limit of the load. Lateral elastic coefficients of compression springs were 1.7_??_2.8×106 gf/mm2 and those of tension springs were 1.0_??_1.710×106 gf/mm2. They were found to posess a sensitivity responding to the slightest stress.Permanent set in fatigue of the carbon spring was not observed.
A study on the mechanism of the occurrence of current oscillation observed in a SOGICON (Semiconductor Oscillation Generator by Injection and CONstriction) type planar device was made. Samples having n-channel region were prepared by selective thermal diffusion of phosphorus on the p-type Si substrate. For comparison, p-channel type samples were also fabricated by thermal diffusion of boron on the n-type Si substrate, the resistivity of substrates being 100 Ω•cm. By applying a pulse voltage across the specimen, oscillation waveforms were observed under various conditions. The oscillation characteristics between n-type and p-type samples were compared in order to clarify the mechanism of the occurrence of current oscillation.