Suppression of boron penetration in p+ polysilicon gateP-MOSFETs using low-temperature gate-oxide N2O anneal

It has been reported that high-temperature (~1100°C) N₂ O-annealed oxide can block boron penetration from poly-Si gates to the silicon substrate. However, this high-temperature step may be inappropriate for the low thermal budgets required of deep-submicron ULSI MOSFETs. Low-temperature (900~950°C) N₂O-annealed gate oxide is also a good barrier to boron penetration. For the first time, the change in channel doping profile due to compensation of arsenic and boron ionized impurities was resolved using MOS C-V measurement techniques. It was found that the higher the nitrogen concentration incorporated at Si/SiO₂ interface, the more effective is the suppression of boron penetration. The experimental results also suggest that, for 60~110 Å gate oxides, a certain amount of nitrogen (~2.2%) incorporated near the Si/SiO₂ interface is essential to effectively prevent boron diffusing into the underlying silicon substrate     

A digital automatic current control system based on an optimumassumed model

In this paper, a new ACR (automatic current regulator) scheme is introduced for brushless DC motors. It consists of a model closely resembling the motor and PWM inverter, an assumed rising pattern of the current, and a parameter estimation. Using the control scheme, the mean value of the motor current is kept at the reference current, and the transient current of the motor is kept equal to the rising pattern. For the disturbance, because of DC-line voltage change, the proportional path from the error to the duty cycle of the PWM signal stabilizes the ACR. This ACR scheme can be realized with a microcomputer     

The NC-REN meets the North Carolina Information Highway

The North Carolina Research and Education Network (NC-REN), formerly known as CONCERT, is an existing video and data network, owned and operated by MCNC. NC-REN's purpose has been to provide network-based support for collaboration in the research community within the state since 1985. The first major application planned for the North Carolina Information Highway (NCIH) is an interactive video distance learning system. A secondary application proposed is the use of Switched Multimegabit Data Service (SMDS) as a means of providing data communications services over NCIH. The user community currently supported by NC-REN has come to expect high levels of service, reliability, interoperability and performance for data and video communications. MCNC is committed to see that NC-REN users receive service that is equal to or better than what is currently provided by the existing network. The prospect of migrating NC-REN-provided services to NCIH-provided transport has raised challenging technical and unique service issues     

Evaluation technique of gate oxide damage

Gate oxide damage by plasma processing was evaluated using structures with various antenna lengths. The gate oxide damage by plasma processing was found to be monitored quantitatively by measuring the charge to breakdown, Q_BD. From the Q_BD measurements, we have confirmed that the degradation occurs during overetching, not in main etching. Plasma current was calculated from the decrease of Q_BD during the etching. The breakdown spot in the gate oxide was detected by photon emission and TEM. The LOCOS structure plays an important role for the degradation by plasma damage. In this paper, it is demonstrated that the Q_BD method is effective for realizing a highly reliable process against plasma damage     

Energy minimization and design for testability

The problem of fault detection in general combinational circuits is NP-complete. The only previous result on identifying easily testable circuits is due to Fujiwara who gave a polynomial time algorithm for detecting any single stuck fault inK-bounded circuits. Such circuits may only contain logic blocks with no more thanK input lines and the blocks are so connected that there is no reconvergent fanout among them. We introduce a new class of combinational circuits called the (k, K)-circuits and present a polynomial time algorithm to detect any single or multiple stuck fault in such circuits. We represent the circuit as an undirected graphG with a vertex for each gate and an edge between a pair of vertices whenever the corresponding gates have a connection. For a (k, K)-circuit,G is a subgraph of ak-tree, which, by definition, cannot have a clique of size greater thank+1. Basically, this is a restriction on gate interconnections rather than on the function of gates comprising the circuit. The (k, K)-circuits are a generalization of Fujiwara'sK-bounded circuits. Using the bidirectional neural network model of the circuit and the energy function minimization formulation of the fault detection problem, we present a test generation algorithm for single and multiple faults in (k, K)-circuits. This polynomial time aggorithm minimizes the energy function by recursively eliminating the variables.     

Spread-spectrum communication techniques

Spread-spectrum modulation can be used in a radio system to reduce the likelihood of intercept, as well as providing some protection against jamming and interference. These antijam, anti-interference and low-probability-of-intercept properties are highly desirable in secured communication systems. In addition, spread-spectrum techniques have been proposed to combat spectral congestion by improving the efficiency of spectrum utilisation. Spread-spectrum techniques are also widely used in ranging systems and in local-area networks (LANs) or other multiple-access systems. In the present article, the three main spread-spectrum techniques are outlined and then applications of frequency-hopping systems and some of the techniques used are described     

Determination of Structure Corrections using Geodetic VLBI Observations of Fiducial Extragalactic Radio Sources

We present the further development of the mathematical technique for calculating the structure corrections using VLBI images of fiducial extragalactic radio sources entering the celestial reference frame. In contrast to techniques described in the literature, the proposed approach can be applied to arbitrary images rather than to images which can be represented by a few Gaussian or delta functions. This is especially topical in view of the appearance of new sophisticated and high-precision image-reconstruction techniques different from the conventional CLEAN procedure or model fitting. The calculation efficiency of the structure corrections is ensured by using the algorithm of fast Fourier transform. We apply the proposed method to analyze a sufficiently representative sample of 36 fiducial extragalactic sources entering the celestial reference frame and illustrate its use for four sources, 1357+769, 0229+131, 2201+315, and 2200+420, each of them belonging to one of the four structure-index classes.     

Spin-relaxation and magnetoresistance in FM/SC/FM tunnel junctions

The effect of spin relaxation on tunnel magnetoresistance (TMR) in a ferromagnet/superconductor/ferromagnet (FM/SC/FM) double tunnel junction is theoretically studied. The spin accumulation in SC is determined by balancing of the spin-injection rate and the spin-relaxation rate. In the superconducting state, the spin-relaxation time τ_s becomes longer with decreasing temperature, resulting in a rapid increase of TMR. The TMR of FM/SC/FM junctions provides a useful probe to extract information about spin-relaxation in superconductors.     

LIDAR mapping of ozone-episode dynamics in Paris and intercomparison with spot analyzers Supplementary material available at http://link.springer.de/journals/apb

Continuous mapping of an ozone episode in Paris in June 1999 has been performed using a differential absorption lidar system. The 2D ozone concentration vertical maps recorded over 33 h at the Champ de Mars are compiled in a video clip that gives access to local photochemical dynamics with unprecedented precision. The lidar data are compared over the whole period with point monitors located at 0-, 50-, and 300-m altitudes on the Eiffel Tower. Very good agreement is found when spatial resolution, acquisition time, and required concentration accuracy are optimized. Sensitivity to these parameters for successful intercomparison in urban areas is discussed. Received: 11 February 2002 / Published online: 14 March 2002     

Mechanism analysis of gate-induced drain leakage in off-state n-MOSFET

An analytical expression for both band-to-band and band-trap-band indirect tunnelings is used to study the gate-induced drain leakage (GIDL) current of MOSFETs measured before and after hot-carrier stress. The voltage and temperature dependence of GIDL are characterized. Both results show that interface traps situated near the midgap participate in the conduction of GIDL, and band-trap-band indirect tunneling could be the major mechanism. This is further supported by the fact that the percentage increase in GIDL induced by hot-carrier stress is about the same as the corresponding increase in interface-trap density. On the other hand, under low-field conditions, trap-assisted Poole–Frenkle emission dominates over tunneling for temperatures even well below room temperature.