We have investigated the relationship between particle removal efficiency and etched depth in SC-1 solution (the mixture composed of ammonium hydroxide, hydrogen peroxide and DI water) for Si wafers. The Si etching rate increases with increasing NH4OH (ammonium hydroxide) concentration. The particle removal efficiency depends on the etched Si depth, and is independent of NH4OH concentration. The minimum required Si etching depth to get over 95% particle removal efficiency is 4 nm. Particles on the Si wafers exponentially decrease with increasing the etched Si depth. However the particle removal efficiency is not affected by particle size ranging from 0.2 to 0.5 µm. The particle removal mechanism on the Si wafers in SC-1 solution is dominated by the lift-off of particles due to Si undercutting and redeposition of the removed particle.

For a discrete Lyapunov matrix equation, we present another such equation that shares the solution to the original one. This renders some existing lower bounds for measures of the size of the solution meaningful, when they yield only trivial bounds. A generalization of this result is suggested.

A design rule relaxation approach is one of the most important requirements for high density DRAMs. The approach relaxes the design rule of a element in comparison with the memory cell size and provides high density DRAMs with the minimum development of a scaled-down MOS structure and a fine patterning lithography process. This paper describes two design rule relaxation approaches, a close-packed folded (CPF) bit-line cell array layout and a Boosted Dual Word-Line scheme. The CPF cell array provides 1.26 times wider active area pitch and maximum 1.5 times wider isolation width. The Boosted Dual Word-Line scheme provides 2n times wider 1st Al pitch on memory cell array, double word-line driver pitch and 1.5 times larger design rule for 1st Al and contacts under 1st Al. Especially wide design rule of the Boosted Dual Word-Line scheme provides several times depth of focus (DOF) for 1st Al wiring which gives several times higher storage node and larger capacitance for capacitor over bit-line (COB) stacked capacitor cells. These approaches are successfully implemented in a 4 Mb DRAM test chip with a 0.91.8 µm2 memory cell.

A technique to realize a transconductance which is relatively insensitive over temperature variations is reported. Simulation results with MOS and bipolar transistors indicate substantial improvement in temperature insensitivity over a range exceeding 100 degrees Celsius. It should find useful applications in analog LSI/VLSI systems operating over a wide range of temperature.

Among various photonic switching technologies, photonic frequency division multiplexing technology is most promising. In this paper a novel photonic FDM (Frequency Division Multiplexing) system is proposed. The proposed system consists of n (multiplicity of frequencies) independent subnetworks, each of which is identified by a specific frequency, and of which each network topology is identical. When a connection is required by a terminal, the network selects a subnetwork that can afford it, and assigns a frequency representing the selected subnetwork to the terminal. This system eliminates frequency converting devices and traffic concentration equipment, which will reduce the size and cost of the system. A very small sized switching system of very large capacity will be easily realized. In this paper, first we will address the basic concept of the proposed system, and then discuss some technical problems and their solutions concerning network configuration, switch matrix structure, subscriber network configuration, control scheme and frequency multiplicity. Some experimental results are also mentioned.

The photonic Space-Division (SD) switching network is attractive for constructing flexible broadband networks. This paper first describes possible applications of the network. A broadband STM switching system, Digital Cross-connect System (DCS) and Video signal distribution switch, especially for HDTV signals, are attractive near term applications. Recent activities on photonic SD switching network developments aiming at these application are also reviewed. A 128 line prototype switching system has been developed. This system utilizes LiNbO3 photonic switch matrices, semiconductor traveling wave amplifiers (TWAs) and three dimensional optical interconnections for multi stage switching networks. It is confirmed that the system has been operating in providing 150Mb/s TV phone services and 600Mb/s HDTV distribution services with high stability. An experimental optical Digital Crossconnect System (optical DCS) has also been demonstrated. Line failure restoration operation at 2.4Gb/s has been successfully demonstrated. These experimental demonstrations prove that practical photonic switching systems are feasible with current technologies.

A new mobility model dependent upon electron concentration is presented for studying the screening effect on ionized impurity scattering. By coupling this model with the drift-diffusion and Hartree models, the effects of self-consistent and quasi-equilibrium screening on carrier transport in heavily doped systems are revealed for first time. The transport mechanism is found to be dominated by the electron-concentration-dependent mobility, and transconductance is shown to be determined by effective mobility and changes from degraded to enhanced characteristics with electron concentration modulation.

We consider a communication system in which a transmitter is connected to a receiver through parallel channels, and the Go-Back-N ARQ scheme is used to handle transmission errors. A packet error on one channel results in retransmission of packets assigned to other channels under the Go-Back-N ARQ scheme. Therefore, the channel-grouping (a grouped-channel is used to transmit the same packet at a time), would affect the throughput performance. We analyze the throughput performance, and give a tree-algorithm to efficiently search for the optimal channel-grouping which makes the throughput to become maximum. Numerical results show that the throughput is largely improved by using the optimal channel-grouping.

The well-known closure tests, the cycling closure test (CCT) and the meet-in-the-middle closure test (MCT), were introduced by Kaliski, Rivest and Sherman to analyze the algebraic properties of cryptosystems, and CCT indicates that DES is not closed. Though Coppersmith presented that DES can be proved not to be closed by a particular way, the closure tests can check various kinds of cryptosystems generally. Thus, successors to MCT and CCT have been proposed at CRYPTO. This paper expands the MCT successor, the switching closure test (SCT), to apply to the DES-like cryptosystems, and shows that this SCT variant is more efficient than the closure test proposed at CRYPTO'92, because the SCT variant establishes a better relationship between the computation cost and the probability of error (the evaluation index). The MCT successors are more important than the CCTs, because the MCTs can directly break closed cryptosystemes. Therefore, if you want to detect the closure property of cryptosystems generally, the SCT variant is better.

Server aided secret computation (SASC) protocol also called the verifiable implicit asking protocol, is a protocol such that a powerful untrusted auxiliary device (server) can help a smart card (client) for computing a secret function efficiently. In this paper, we extend the concept of addition sequence to the secure addition sequence and develop an efficient algorithm to construct such sequence. By incorporating the secure addition sequence into the SASC protocol the performance of SASC protocol can be further enhanced.

It is recognized in Japan that reformation of the national research institutions is urgently necessary. Present situation and constraints are shown and the action items are discussed.

This paper considers the subliminal channel, hidden in an identification scheme, for transferring signatures. We observe the direct parallelization of the Fiat-Shamir identification scheme has a subliminal channel for the transmission of the digital signature. A positive aspect of this hidden channel supplies us how to transfer signatures without secure channels. As a formulation of such application, we introduce a new notion called privately recordable signature. The privately recordable signature is generated in an interactive protocol between a signer and a verifier, and only the verifier can keep the signatures although no third adversary can record the signatures. ln this scheme, then the disclosure of the verifier's private coin turns the signer's signature into the ordinary digital signature which is verified by anybody with the singer's public key. The basic idea of our construction suggests the novel primitive that a transferring securely signatures without secret channels could be constructed using only one-way function (without trapdoor).

New focused ion beam (FIB) methods for microscopic cross-sectioning and observation, microscopic crosssectioning and elemental analysis, and aluminum film microstructure observation are presented. The new methods are compared to the conventional methods and the conventional FIB methods, from the four viewpoints such as easiness of analysis, analysis time, spatial resolution, and pinpointing precision. The new FIB methods, as a result, are shown to be the best ones totally judging from the viewpoints shown above.

Beam-steering devices are attractive for spatial optical interconnections. Those devices are essential not only for fixed connecting routed optical interconnections, but for flexible connecting routed optical interconnections. The flexible connecting routed optical interconections are more powerful than the conventional fixed connecting routed ones. Structures and characteristics of beam-steering devices, a beam-scanning laser diode and a fringe-shifting laser diode, are reported for those interconnections. Using these lasers, the configurations of several optical interconnections, such as optical buses and optical data switching links as examples of fixed and flexible connecting routed optical interconnections are discussed.

This paper presents a zero-knowledge interactive protocol that demonstrates two factors a and b of a composite number n (=ab) are really known by the prover, without revealing the factors themselves. Here the factors a and b need not be primes. The security of the protocol is based on the difficulty of computing discrete logarithms modulo a large prime.

A full-wave analysis for the scattering problem of infinite periodic arrays on dielectric substrates excited by a circularly-polarized incident wave is presented. The impedance boundary condition is solved by using the moment method in the spectral domain. Numerical results are given and scattering properties are discussed.

In this article, we consider a hysteresis oscillator which includes periodic thresholds. This oscillator relates to a model of human's sleep-wake cycles. Deriving a one dimensional return map rigorously, we can clarify existence regions of various periodic attractors in some parameter subspace. Also, we clarify co-existence regions of periodic attractors and existence regions of quasi-periodic attractors. Some of theoretical results are confirmed by laboratory measurements.

This paper gives a systematic approach to generate a Markov chain by a discrete-valued auto-regressive equation, which is a a nonlinear auto-regressive equation having a discrete-valued solution. The power spectrum, the correlation function and the transition probability are explicitly obtained in terms of the discrete-valued auto-regressive equation. Some computer results are illustrated in figures.

High variability of object features and bad class separation of objects are the main causes for the difficulties encountered during the interpretation of ground-level natural scenes. For coping with these two problems we propose a method which extracts those regions that can be segmented and immediately recognized with sufficient reliability (core regions) in the first stage, and later try to extend these core regions up to their real object boundaries. The extraction of reliable core regions is generally difficult to achieve. Instead of using fixed sets of features and fixed parameter settings, our method employs multiple local features (including textural features) and multiple parameter settings. Not all available features may yield useful core regions, but those core regions that are extracted from these multiple features make a cntributio to the reliability of the objects they represent. The extraction mechanism computes multiple segmentations of the same object from these multiple features and parameter settings, because it is not possible to extract such regions uniquely. Then those regions are extracted which satisfy the constraints given by knowledge about the objects (shape, location, orientation, spatial relationships). Several spatially overlapping regions are combined. Combined regions obtained for several features are integrated to form core regions for the given object calss.

The potential distribution around a linear array of donor atoms in a semiconductor crystal is calculated, approximating the linear array by a continuous line charge. Two methods are used for the analysis. One is the self-consistent calculation of Poisson's equation and the effective mass Schrödinger's equation, and the other is the Thomas-Fermi approximation. Results of both methods agree very well, and it is shown that it is possible to form a potential distribution as fine as the electron wavelength by appropriate arrangement of the impurity atoms. Arrays of impurity atoms therefore can act as buiding elements for future electron wave devices.