Mechanical stress control in a VLSI-fabrication process: a method for obtaining the relation between stress levels and stress-induced failures

An ideal fabrication process is designed to minimize mechanical stress in semiconductor devices and to improve device reliability. Mechanical stress levels were predicted by in-house simulations supported by a thin-film database. These stress levels were correlated with stress-induced defects by TEM analysis supported by fail bit addressing on matured megabit SRAMs. Amorphous-doped silicon film with various annealing temperatures were used for the gate electrode to change the mechanical stress in devices and to get the direct relationship between predicted stress levels and stress related defects. The authors describe brief guidelines for suppressing dislocations in the small geometry shallow-trench isolation process utilizing this system. Polysilicon thickness in the W-polycide gate electrode is designed to minimize mechanical stress in the gate oxide and to suppress the gate oxide failure in probe and class tests. Moreover, critical stress generates dislocations during post source/drain ion implantation anneal obtained by a ball indentation method. This indicated that lower temperature anneal is effective in suppressing the dislocations. A two-step anneal was introduced to suppress dislocations and to enable higher ion activation.     

STRUCTURE FORMATION OF COATED FILMS WITH DISPERSED PIGMENTS DURING DRYING

In the drying of coated films with dispersed pigments, such as floppy disks, the structure of the film is formed during the drying process and depends on the drying condition. It is important to understand the structure formation during drying for the design of the dryer and die better quality of the product. We measured die drying characteristics of the film and determined the structure of dried film experimentally. A qualitative model for the structure formation during drying of the coated film is suggested.     

Development of cable fault location method using fiber optic distributed temperature sensor

When ground-fault problems occur on a cable line, immediate fault location and restoration are required. Therefore, various new methods to locate the fault point instantaneously have been investigated to replace such conventional methods as the Murray loop method and the pulse radar method [1]. These methods require a long time to locate the fault point. One possible fault location method is to sense the temperature rise following a ground fault using a fiber optic distributed temperature sensor. Application of this method was found feasible through sensing the temperature rise at a ground-fault test using a thermocouple as a temperature sensor with test cables [4]. A power/optical composite cable was prepared experimentally and after verifying its thermal mechanical performance, the temperature rise at an incidence of a fault was determined and the anticipated performance was demonstrated in a ground-fault test. This article describes the outline of the test.     

The effect of probability of coalescence on the evolution of bubble sizes in a turbulent pipeline flow: A numerical study

A population balance method in which continuum and discrete phases are integrated is developed to simulate the evolution of polydisperse population of bubbles in a turbulent pipeline flow. The investigation is focused on the effect of the coalescence efficiency on this evolution. A dilute system of bubbles under microgravity conditions is considered. It is found that if the initial coalescence efficiency is low, a slight increase produces a significant effect on the bubble coalescence rate, and thus on the evolution of the population. If, however, the initial coalescence efficiency is high, its increase results in a marginal effect on the way the population evolves. The results of simulations are validated against experimental data on the population mean.     

Fabrication of blue-light emission fused-silica substrates by using Si-ion implantation and high-temperature annealing

We fabricated fused-silica substrates which emit blue light by using Si-ion implantation and high-temperature annealing. Photoluminescence peak wavelengths are around 400 nm, and the peak intensities can be remarkable after annealing above 1150 °C.     

Effect of inhibitors on ω-and (ω-1)-hydroxylation of lauric acid by frog liver microsomes

To investigate the involvement of different cytochrome P-450 monooxygenases in fatty acid hydroxylation in frog liver microsomes, the effect of various inhibitors of cytochrome P-450 monooxygenases on the ω- and (ω-1)-hydroxylation of laurate was examined. The ω/ω-1-hydroxylation ratios were changed significantly by various levels of carbon monooxide (CO) inhibition; the formation of ω-hydroxylaurate was more sharply inhibited by various levels of CO than was the formation of (ω-1)-hydroxylaurate. On the contrary, metyrapone inhibited only the formation of (ω-1)-hydroxylaurate and stimulated the formation of ω-hydroxylaurate. 7,8-Benzoflavone as well as CO was more inhibitory to the ω-hydroxylation of laurate. At low concentrations of KCN (0.2 and 0.1 mM), the (ω-1)-hydroxylase activity was stimulated, but both the ω- and (ω-1)-hydroxylase activities were inhibited at the higher concentrations (5–10 mM). The effect of drugs and hydroxylaurate isomers on the ω- and (ω-1)-hydroxylation was also examined. Aminopyrine showed a stimulative effect on ω-hydroxylase activity and no effect on the (ω-1)-hydroxylase activity, whilep-nitroanisole inhibited the (ω-1)-hydroxylase activity and showed almost no effect on the ω-hydroxylase activity. 12-Hydroxylaurate inhibited both the ω- and (ω-1)-hydroxylase activities, but the ω-hydroxylase activity was inhibited to a much greater extent. 11-Hydroxylaurate had no effect on either hydroxylation. These findings strongly support the hypothesis that different cytochrome P-450 species are involved in the hepatic microsomal hydroxylation of laurate at ω- and (ω-1)-positions in the frog.     

Theranostic Agent Combining Fullerene Nanocrystals and Gold Nanoparticles for Photoacoustic Imaging and Photothermal Therapy

Developing photoactivatable theranostic platforms with integrated functionalities of biocompatibility, targeting, imaging contrast, and therapy is a promising approach for cancer diagnosis and therapy. Here, we report a theranostic agent based on a hybrid nanoparticle comprising fullerene nanocrystals and gold nanoparticles (FGNPs) for photoacoustic imaging and photothermal therapy. Compared to gold nanoparticles and fullerene crystals, FGNPs exhibited stronger photoacoustic signals and photothermal heating characteristics by irradiating light with an optimal wavelength. Our studies demonstrated that FGNPs could kill cancer cells due to their photothermal heating characteristics in vitro. Moreover, FGNPs that are accumulated in tumor tissue via the enhanced permeation and retention effect can visualize tumor tissue due to their photoacoustic signal in tumor xenograft model mice. The theranostic agent with FGNPs shows promise for cancer therapy.     

Thermal cis–trans conversion in thiophene oligomers

Thermal cis–trans conversion has been examined in oligothiophene single molecules encapsulated in the molecular vessels of cyclodextrin and Na-mordenite. At high temperatures, optical absorption intensities are enhanced in bithiophene, terthiophene and quinquethiophene, while the intensity of quarterthiophene is temperature independent. Optical absorption comes from uncompensated transition dipole moment due to the thermal torsion between cis and trans forms.     

A Low-Loss Built-In Current Sensor

This paper presents a novel built-in current sensor that uses two additional power supply voltages besides the system power supply voltage, and that is constructed by using a current mirror circuit to pick up an abnormal IDDQ. It is activated only by an abnormal quiescent power supply current and minimizes the voltage drop at the terminal of the circuit under test. Simulation results showed that it could detect 16-A IDDQ against 0.03-V voltage drop at 3.3-V VDD and that it reduced performance degradation in the circuit under test. It is therefore suitable for testing low-voltage integrated circuits. Moreover, we verified the behavior of the sensor circuit implemented on the board by using discrete devices. Experimental results showed that the real circuit of the sensor functioned properly.