53,354 research outputs found
Reliability characterization and prediction of high k dielectric thin film
Full text linkAs technologies continue advancing, semiconductor devices with dimensions in nanometers have entered all spheres of human life. This research deals with both the statistical aspect of reliability and some electrical aspect of reliability characterization. As an example of nano devices, TaOx-based high k dielectric thin films are studied on the failure mode identification, accelerated life testing, lifetime projection, and failure rate estimation.
Experiment and analysis on dielectric relaxation and transient current show that the relaxation current of high k dielectrics is distinctive to the trapping/detrapping current of SiO2; high k films have a lower leakage current but a higher relaxation current than SiO2. Based on the connection between polarization-relaxation and film integrity demonstrated in ramped voltage stress tests, a new method of breakdown detection is proposed. It monitors relaxation during the test, and uses the disappearing of relaxation current as the signal of a breakdown event.
This research develops a Bayesian approach which is suitable to reliability estimation and prediction of current and future generations of nano devices. It combines the Weibull lifetime distribution with the empirical acceleration relationship, and put the model parameters into a hierarchical Bayesian structure. The value of the Bayesian approach lies in that it can fully utilize available information in modeling uncertainty and provide cogent prediction with limited resources in a reasonable period of time. Markov chain Monte Carlo simulation is used for posterior inference of the reliability projection and for sensitivity analysis over a variety of vague priors.
Time-to-breakdown data collected in the accelerated life tests also are modeled with a bathtub failure rate curve. The decreasing failure rate is estimated with a non-parametric Bayesian approach, and the constant failure rate is estimated with a regular parametric Bayesian approach. This method can provide a fast and reliable estimation of failure rate for burn-in optimization when only a small sample of data is available
The Interrelationship Between N Policy M/G/1/K and F Policy G/M/1/K Queues with Startup Time
No full text[[abstract]]This paper studies the interrelationship between the N - policy M/G/1/K queue and the F - policy G/M/1/K queue. The N - policy queuing problem investigates the most common issue of controlling service. The F - policy queuing problem deals with the most common issue of controlling arrivals. We provide a recursive method, using the supplementary variable technique and treating the supplementary variable as the remaining service time, to develop the solution algorithm for the - N policy M/G/1/K queue with startup time. We have demonstrated that the N - policy M/G/1/K queue with startup time has been effectively used to derive the solution algorithm to the F - policy G/M/1/K queue with startup time. The interrelationship between the N - policy and the F - policy queueing problems are illustrated analytically for 3-stage Erlang (service or interarrival) time distribution
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
Full text linkThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
Kwanghwana miscanthi Karun., C. H. Kuo & K. D. Hyde 2020, sp. nov.
No full textKwanghwana miscanthi Karun., C.H.Kuo & K.D.Hyde, sp. nov. (Fig. 2) INDEX FUNGORUM NUMBER. — IF557101. FACESOFFUNGI NUMBER. — FoF 07776. ETYMOLOGY. — Refers to the generic name for the host. HOLOTYPE. — MFLU 18-1950. CULTURE CHARACTERS. — Colonies on PDA slow growing at 20-25° C, circular, white at the growing edge, light to dark pink in the centre; reverse white at the edge, the centre dense, convex or dome-shaped to umbonate, with entire edge, glabrous with tiny granular on surface, no pigment produced. MATERIAL EXAMINED. — Taiwan, Chiayi Province, Kwang Hwa, alt. 1330 m, 23°30.084’N, 120°41.73.5’ E on Miscanthus floridulus (Poaceae) leaf sheath, 17.III.2018, A. Karunarathna, AKTW 05 (holo-, MFU [MFU 18-1952]), ex-type living culture, FU 31017, NCYUCC 19-0372. DESCRIPTION Associated with Miscanthus floridulus (Poaceae) leaf sheath. Sexual state Ascomata. 130-150 µm × 160-170 µm. (ẍ = 138 × 168 µm, n = 5), immersed or semi-immersed, visible as minute black dots on host surface, uniloculate, subglobose, brown to dark brown, solitary; centrally ostiolate, circular, papillate. Peridium. 20-30 µm wide, with 7-9 layers at the apex and 3-4 layers at the base, thinner towards the base, the outer layers composed of brown, thick-walled cells of textura angularis, the inner layers composed of hyaline to pale brown, thin-walled cells of textura prismatica. Hamathecium. Composed of numerous,hyaline,frequently septate, broadly cellular 2-3µm wide pseudoparaphyses,often constricted at the septa, branching at the mid-point, embedded in mucilage. Asci. 60-70 × 10-13 µm (ẍ = 67.5 × 11 µm, n = 30), 8-spored, bitunicate, cylindrical to cylindric-clavate, short pedicellate, apically rounded with well-developed narrowly ocular chamber, smooth-walled, arising from the base of ascoma. Ascospores. 16-18.5 × 5-6 µm (ẍ = 17 × 5 µm, n = 40), fusiform, broadly fusoid with rounded ends, hyaline, overlapping or irregularly biseriate, 3-septate, the cells above and below the middle septum are broader, upper cell is comparatively broader, smooth-walled with large guttules; germinating within 12 hours on PDA, geminating from end cells. Asexual state Unknown.Published as part of Karunarathna, Anuruddha, Phookamsak, Rungtiwa, Jayawardena, Ruvishika S., Hyde, Kevin D. & Kuo, Chang H., 2020, Kwanghwana miscanthi Karun., C. H. Kuo & K. D. Hyde, gen. et sp. nov. (Phaeosphaeriaceae, Pleosporales) on Miscanthus floridulus (Labill.) Warb. ex K. Schum. & Lauterb. (Poaceae), pp. 119-132 in Cryptogamie, Mycologie 20 (6) on pages 124-128, DOI: 10.5252/cryptogamiemycologie2020v41a6, http://zenodo.org/record/782632
Epithelioid trophoblastic tumor of the broad ligament: A case report and review of the literature.
No full text∑_(l+m=k,l,m≥0) ((α+l-1)¦l) ((β+m-1)¦m)=((α+β+k-1)¦k) and its application to negative binomial distribution
Full text linkWe prove here the following equation: ∑_(l+m=k,l,m≥0) ((α+l-1)¦l) ((β+m-1)¦m)=((α+β+k-1)¦k) and give its application to prove the reproductive property of the negative binomial distribution.
These finite sum equation involving binomial coefficients and proof of the reproductive property are not known as far as the author knows.論文(Article)departmental bulletin pape
Shaping the Optimal Repetition Interval for Cathodal Transcranial Direct Current Stimulation (tDCS)
No full textMonte-Silva K, Kuo M-F, Liebetanz D, Paulus W, Nitsche MA. Shaping the optimal repetition interval for cathodal transcranial direct current stimulation (tDCS). J Neurophysiol 103: 1735-1740, 2010. First published January 27, 2010; doi: 10.1152/jn.00924.2009. Transcranial DC stimulation (tDCS) is a plasticity-inducing noninvasive brain stimulation tool with various potential therapeutic applications in neurological and psychiatric diseases. Currently, the duration of the aftereffects of stimulation is restricted. For future clinical applications, stimulation protocols are required that produce aftereffects lasting for days or weeks. Options to prolong the effects of tDCS are further prolongation or repetition of tDCS. Nothing is known thus far about optimal protocols in this behalf, although repetitive stimulation is already performed in clinical applications. Thus we explored the effects of different break durations on cathodal tDCS-induced cortical excitability alterations. In 12 subjects, two identical periods of cathodal tDCS (9-min duration; 1 mA) with an interstimulation interval of 0 (no break), 3, or 20 min or 3 or 24 h were performed. The results indicate that doubling stimulation duration without a break prolongs the aftereffects from 60 to 90 min after tDCS. When the second stimulation was performed during the aftereffects of the first, a prolongation and enhancement of tDCS-induced effects for <= 120 min after stimulation was observed. In contrast, when the second stimulation followed the first one after 3 or 24 h, the aftereffects were initially attenuated, or abolished, but afterwards re-established for up to 120 min after tDCS in the 24-h condition. These results suggest that, for prolonging the aftereffects of cathodal tDCS, stimulation interval might be important
Zirconium-doped tantalum oxide high-k gate dielectric films
Full text linkA new high-k dielectric material, i.e., zirconium-doped tantalum oxide (Zr-doped TaOx), in the form of a sputter-deposited thin film with a thickness range of 5-100 nm, has been studied. Important applications of this new dielectric material include the gate dielectric layer for the next generation metal-oxide-semiconductor field effect transistor (MOSFET). Due to the aggressive device scaling in ultra-large-scale integrated circuitry (ULSI), the ultra-thin conventional gate oxide (SiO2) is unacceptable for many practical reasons. By replacing the SiO2 layer with a high dielectric constant material (high-k), many of the problems can be solved. In this study, a novel high-k dielectric thin film, i.e., TaOx doped with Zr, was deposited and studied. The films electrical, chemical, and structural properties were investigated experimentally. The Zr dopant concentration and the thermal treatment condition were studied with respect to gas composition, pressure, temperature, and annealing time. Interface layer formation and properties were studied with or without an inserted thin tantalum nitride (TaNx) layer. The gate electrode material influence on the dielectric properties was also investigated. Four types of gate materials, i.e., aluminum (Al), molybdenum (Mo), molybdenum nitride (MoN), and tungsten nitride (WN), were used in this study. The films were analyzed with ESCA, XRD, SIMS, and TEM. Films were made into MOS capacitors and characterized using I-V and C-V curves. Many promising results were obtained using this kind of high-k film. It is potentially applicable to future MOS devices
Hafnium-doped tantalum oxide high-k gate dielectric films for future CMOS technology
Full text linkA novel high-k gate dielectric material, i.e., hafnium-doped tantalum oxide (Hf-doped
TaOx), has been studied for the application of the future generation metal-oxidesemiconductor
field effect transistor (MOSFET). The film's electrical, chemical, and
structural properties were investigated experimentally. The incorporation of Hf into TaOx
impacted the electrical properties. The doping process improved the effective dielectric
constant, reduced the fixed charge density, and increased the dielectric strength. The
leakage current density also decreased with the Hf doping concentration. MOS capacitors
with sub-2.0 nm equivalent oxide thickness (EOT) have been achieved with the lightly
Hf-doped TaOx. The low leakage currents and high dielectric constants of the doped films
were explained by their compositions and bond structures. The Hf-doped TaOx film is a
potential high-k gate dielectric for future MOS transistors.
A 5 ����
tantalum nitride (TaNx) interface layer has been inserted between the Hf-doped
TaOx films and the Si substrate to engineer the high-k/Si interface layer formation and
properties. The electrical characterization result shows that the insertion of a 5 ����
TaNx
between the doped TaOx films and the Si substrate decreased the film's leakage current density and improved the effective dielectric constant (keffective) value. The improvement
of these dielectric properties can be attributed to the formation of the TaOxNy interfacial
layer after high temperature O2 annealing. The main drawback of the TaNx interface layer
is the high interface density of states and hysteresis, which needs to be decreased.
Advanced metal nitride gate electrodes, e.g., tantalum nitride, molybdenum nitride,
and tungsten nitride, were investigated as the gate electrodes for atomic layer deposition
(ALD) HfO2 high-k dielectric material. Their physical and electrical properties were
affected by the post metallization annealing (PMA) treatment conditions. Work functions
of these three gate electrodes are suitable for NMOS applications after 800������C PMA.
Metal nitrides can be used as the gate electrode materials for the HfO2 high-k film.
The novel high-k gate stack structures studied in this study are promising candidates
to replace the traditional poly-Si-SiO2 gate stack structure for the future CMOS
technology node
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