Recently, the miniaturization of MOS transistors, which has been the driving force of LSI evolution, is becoming difficult because of “random variations” caused by microscopic perturbations. In this paper, after reviewing various kinds of variability, including the above, the recent findings concerning the root cause of random variations is described. Finally, the directions that should be taken in device development to reduce the variations are discussed.

Dielectric breakdown is a local phenomenon. This indicates that application of high electric stress to silicon dioxide films induces two-dimensional degradation. The degradation closely related to charge trapping within the films. The wet etching of stressed films makes the nonuniformity of the trapped charge distribution clearly observable. The two-dimensional distribution can be attributed to the microroughnesses at the surface and interface of the silicon dioxide films or the nonuniformity of the film thickness.

Research and development activities related to coherent optical communications, which aim at the full utilization of optical carriers including the optical phase, are now being undertaken again after almost twenty years of interruption. The new generation of such coherent optical communications features the combination of conventional optical technology and fast digital signal processing, and is now called digital-coherent optical communications. After briefly reviewing the thirty-year history of coherent optical communications, we discuss the possibilities that digital-coherent technology may afford us in future optical networks.

Despite many studies on the dispersion of the electron energy band, it has been difficult to analyze its character, such as the type of atomic orbitals constituting the band, its bonding character, and its orbital angular momentum. We have studied these characters as well as the three-dimensional band structure by two-dimensional photoelectron spectroscopy combined with polarized synchrotron radiation. The angular distribution of photoelectron intensity excited by linearly polarized light reveals the atomic orbitals that constitute the valence band. Intensity modulation among different Brillouin zones distinguishes bonding and antibonding character. The dichroism in the angular distribution of photoelectron intensity excited by circularly polarized light reveals the orbital angular momentum of the atomic orbitals constituting the valence band.

The physical background of random telegraph signals, 1/f noise, and charge pumping characteristics in Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) is summarized. Moreover, our recent research on the fluctuation of Si/SiO₂ interface properties in nanoscale MOSFETs is introduced. To clarify the effects of fluctuation on device characteristics, it is important to understand the electrical behaviors of all traps spread throughout the whole energy range of the band gap. In this report, it is shown that proper transient charge-pumping characteristics are observed for individual MOSFETs. It is also shown that the fluctuations in both the number and individual carrier capture rate of interface traps in the whole energy range of the band gap can be detected and evaluated.

The mechanism of typical failure modes such as electromigration (EM), stress migration (SM), and time-dependent dielectric breakdown (TDDB), and the current status of attempts to improve reliability are described focusing on the miniaturization of Cu/low-k multilayer interconnects. The driving forces that cause atomic movement depend on the type of failure mode ; such driving forces include electronic wind force, stress, and electric field. The cause of the poor reliability is considered to be the high diffusivity of atoms on the surface of the Cu wiring and in the barrier dielectric film /low-k film interface.

The Japanese semiconductor industry has been in decline for many years. Consortia and national projects don’t seem to contribute significantly to improving the industry. The achievement of R&D is not poor, but R&D isn’t particularly relevant to difficulties that the industry is facing. The biggest concern of the semiconductor industry is the continuous need to reduce costs rather than to develop cutting edge technology for achieving high performance devices. There are two choices : to develop technology to fabricate semiconductors at an extremely low cost, or to research basic science in preparation for the next generation of semiconductors after Si LSI.

Bottom-up electronics enables us to fabricate single-electron devices and molecular devices with high sub-nm precision by simply dipping a sample into a beaker. To establish these devices, we must control the tunneling probability between nanogap electrodes and the Coulomb island of a Au nanoparticle or a functional molecule by selecting a suitable molecular structure. Both molecular-resolution images and the electrical properties of the Coulomb island can be obtained by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS), respectively. Here, we demonstrate Coulomb blockade phenomena of a Au nanoparticle and a functional molecule by molecular-resolution STM and STS, and introduce established the bottom-up processes toward the realization of solid-state single-electron devices and molecular devices by utilizing the results obtained by STM and STS.

Saccharides on cell surfaces play important roles in living systems, and have recently been paid much attracted considerable attention owing to their relationship with various diseases. We have prepared saccharide materials to mimic the cell surface. We conjugated the saccharides with a substrate and nanoparticles to fabricate novel materials for use in biosensing devices.

We report a study of the reliability of high-k gate dielectrics (negative bias temperature instability (NBTI), positive bias temperature instability (PBTI), time dependent dielectric breakdown (TDDB), and 1/f noise characteristics). In order to understand NBTI, not only the interface state degradation but also the bulk hole traps should be considered. On the other hand, the key point in understanding PBTI is in the bulk electron trap behavior. In the case of TDDB, electron current may play an important role in the breakdown, in contrast to that of SiO₂, which is controlled by holes. For 1/f noise, not only interface traps but also bulk traps should be considered.

A large-array test circuit that is able to precisely and quickly evaluate the reliability of large capacity flash memory has been developed. The test circuit consists of over 80,000 devices per shot and over 5,000,000 devices per wafer. Each device corresponds to a actual cell of flash memory. The test circuit is able to analyze stress-induced leakage currents with 10^-16 A resolution and voltage fluctuations with 1mV resolution in a short time of approximately 50 or 100 seconds. In this paper, the large-array test circuit technique and examples of measurement results are presented.

Vacuums are extensively used in a variety of fields ranging from scientific investigations to technological processes ; this range encompasses atomically controlled nano/surface science and technology, semiconductor processing, and the freeze-drying of foodstuffs. In this article, the basic properties and physics of vacuums are reviewed, such as the mean free path of molecules, the frequency of molecular collisions, gas flow, tube conductance, and so forth.