A 65 nm Embedded SRAM With Wafer Level Burn-In Mode, Leak-Bit Redundancy and Cu E-Trim Fuse for Known Good Die

We propose a wafer level burn-in (WLBI) mode, a leak-bit redundancy and a small, highly reliable Cu E-trim fuse repair for an embedded 6T-SRAM to achieve a known good die (KGD) SoC. We fabricated a 16 Mb SRAM with these techniques using 65 nm LSTP technology, and confirmed the efficient operations of these techniques. The WLBI mode enables simultaneous write operation for 6T-SRAM, and has no area penalty and a speed penalty of only 50 ps. The leak-bit redundancy for 6T-SRAM can reduce the infant mortality of the bare die, and improves the standby current distribution. The area penalty is less than 2%. The Cu E-trim fuse can be used beyond the 45 nm advanced process technology. The fuse requires no additional wafer process steps. Using only 1.2 V core transistors will allow CMOS technology scaling to enable fuse circuit size reduction. The trimming transistor is placed under the fuse due to there being no cracking around the trimmed position. We achieve the small fuse circuit size of 6 x 36 mum² using 65 nm technology.     

Origins of Improved Hole‐Injection Efficiency by the Deposition of MoO3 on the Polymeric Semiconductor Poly(dioctylfluorene‐alt‐benzothiadiazole)

The electronic structure of the interfaces formed after deposition of MoO₃ hole‐injection layers on top of a polymer light‐emitting material, poly(dioctylfluorene‐alt‐benzothiadiazole) (F8BT), is studied by ultraviolet photoelectron spectroscopy (UPS), X‐ray photoelectron spectroscopy and metastable atom electron spectroscopy. Significant band bending is induced in the F8BT film by MoO₃ “acceptors” that spontaneously diffuse into the F8BT “host” probably driven by kinetic energy of the deposited hot MoO₃. Further deposition leads to the saturation of the band bending accompanied by the formation of MoO₃ overlayers. Simultaneously, a new electronic state in the vicinity of the Fermi level appears on the UPS spectra. Since this peak does not appear in the bulk MoO₃ film, it can be assigned as an interface state between the MoO₃ overlayer and underlying F8BT film. Both band bending and the interface state should result from charge transfer from F8BT to MoO₃, and they appear to be the origin of the hole‐injection enhancement by the insertion of MoO₃ layers between the F8BT light‐emitting diodes and top anodes.     

Choking flow modeling with mechanical non-equilibrium for two-phase two-component flow

A mechanistic model which considers the mechanical non-equilibrium is described for two-phase choking flow. The choking mass flux is obtained from the momentum equation with the definition of choking. The key parameter for the mechanical non-equilibrium is a slip ratio. The dependent parameters for the slip ratio are identified. In this research, the slip ratio which is defined in the drift flux model is used to identify the impact parameters on the slip ratio. Because the slip ratio in the drift flux model is related to the distribution parameter and drift velocity, the adequate correlations depending on the flow regime are introduced in this study. In this mechanistic modeling approach, the choking mass flow rate is expressed by the function of pressure, quality and slip ratio. The developed model is evaluated by comparing with the air–water experimental data to eliminate the thermal effect. The comparison of predicted choking model for mechanical non-equilibrium with other experimental data in high quality region (up to 80%) is quite reasonable with a small error.     

Reversible Control of Exo‐ and Endo‐Budding Transitions in a Photosensitive Lipid Membrane

We have developed a method for the photomanipulation of lipid membrane morphology in which the shape of a vesicle can be switched by light through the use of a synthetic photosensitive amphiphile containing an azobenzene unit (KAON12). We prepared cell‐sized liposomes from KAON12 and 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) and conducted real‐time observations of vesicular transformation in the photosensitive liposome by phase‐contrast microscopy. Budding transitions—either budding toward the centre of the liposome (endo‐bud) or budding out of the liposome (exo‐bud)—could be controlled by light. We discuss the mechanism of this transformation in terms of the change in the effective membrane surface area due to photoisomerization of the constituent molecules.     

Theoretical Investigation of Lattice Thermal Vibration Effects on Phase Equilibria Within Cluster Variation Method

First-principles phase equilibria calculations often overestimate an order-disorder transition temperature due to the neglect of local lattice distortion effects originated from the mixture of elements of different atomic sizes. The lattice vibration effects introduced through the Debye-Grüneisen theory within the quasi-harmonic approximation has proven to be quite effective in circumventing the inconveniences. With the preferential enhancement of the stability of a disordered phase by introducing the lattice vibration effects, the transition temperature was reduced considerably. In order to gain further insight into the lattice vibration effects, a systematic investigation of the vibrational free energy of the Debye-Grüneisen theory is attempted on the two-dimensional square lattice which constitutes a prototype study prior to the first-principles calculations on realistic alloy systems. A particular focus of the present study is placed on the effects of Debye temperatures of constituent phases on the transition temperature. It is shown that lattice softening by lattice vibration stabilizes the disordered phase by reducing the energy expended to accommodate atoms of different sizes, which is manifested by the reduction of the curvature of the atomic potentials. It is, however, predicted that an opposite case can also take place. When the Debye temperature of an ordered phase is lower than that of the pure metals, the ordered phase is more stabilized and the inclusion of the lattice vibration effects in the free energy raises the resultant transition temperature.     

Approach for wide use of diagnostic method for XLPE cables using harmonics in AC loss current

A water tree is one aspect of the degradation of XLPE cables used for underground distribution or transmission lines. We have developed the loss current method using the third harmonic in AC loss current for cable diagnosis. The harmonic components in loss current arise as a result of the nonlinear voltage– current characteristics of water trees. We confirmed that the third harmonic in the AC loss current has good correlation with respect to water tree growth and breakdown strength. After that, we applied this method to the actual 66‐kV XLPE cable lines. Up to now, results on over 130 lines have been obtained. In the case of cable lines terminated at gas‐insulated switchgear (GIS), we have to remove the lightning arrestor (LA) and the potential transformer (PT) from the test circuit. The reason is that we are afraid that each LA and PT disturbs the degradation signal from cable lines. It requires extra time (1 or 2 days) and costs more to remove the LA and PT in GIS from a circuit. In order to achieve easy and reasonable diagnosis, we have developed a new method for cable lines terminated at GIS by utilizing a technique that enables one to cancel the signal of the LA and PT from disturbed signal of the cable lines. We confirmed the effect of the new method through experiments with actual cables. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(4): 52–59, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20510     

Synthesis of (CrxV1−x )2O3 fine particles by a laser-induced vapor-phase reaction and their crystal structure

Single-phase crystalline fine particles of (CrxV1–x)2O3 have been synthesized by a vapor-phase explosive reaction of a gas mixture of CrO2Cl2 + VOCl3 + H2 + O2 induced by a single laser pulse. The distribution of particle size was uniform with a mean particle size of 80 nm. Lattice constants of (CrxV1–x)2O3 (x=0–1) were accurately determined by the whole-powder-pattern decomposition (WPPD) method. A sharp increase in the a axis-length and a sharp decrease in the c axis-length of the hexagonal unit cell of the oxide (x=0.03) have been observed. The crystal structures of (CrxV1–x)2O3 (x=0.15, 0.5, 0.7) were studied by Rietveld analysis.     

Fabrication of a submicron patterned electrode using an electrospun single fiber as a shadow-mask

We realize a uniform submicron-gap electrode by using an electrospun single fiber as a shadow-mask. By stretching an electrospun fiber, we can decrease the diameter of the fiber from 2 μm to 564 nm with its standard deviation of 57.7 nm. We place the fiber on the center of a Si/SiO₂ substrate followed by the deposition of a molybdenum trioxide adhesion layer and Au electrode. After removing the fiber from the Si/SiO₂ substrate, the submicron-gap gold electrode is formed. Characterization of the gap with scanning electron microscope revealed that the gap has a good uniformity; the average gap length is 865 nm throughout 2 mm gap width.