Browsing by Author "Yeh, CC"

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A comparative study of SILC transient characteristics and mechanisms in FN stressed and hot hole stressed tunnel oxides
(1999)
Zous, NK
;
Wang, TH
;
Yeh, CC
;
Tsai, CW
;
Huang, CM
The mechanisms and transient characteristics of hot hole stress and FN stress induced excess leakage currents in tunnel oxides are investigated. Hot hole SILC is found to have a more pronounced transient effect. The transient is attributed to positive oxide charge detrapping and thus annihilation of positive charge-assisted tunneling current. The positive charge assisted tunneling current can be annealed by substrate hot electron injection. The DC and transient components in FN SILC are also discussed.
A novel erase scheme to suppress overerasure in a scaled 2-bit nitride storage flash memory cell
(2004-09-01)
Yeh, CC
;
Wang, TH
;
Tsai, WJ
;
Lu, TC
;
Liao, YY
The cause of over-erasure in a two-bit nitride storage Flash memory cell is investigated. Extra positive charges accumulated above the n(+) unction and channel-shortening enhanced drain-induced barrier lowering effect are found to be responsible for threshold voltage (V-t) lowering in an over-erased cell. A modified erase scheme is proposed to resolve this issue. By applying a source voltage during erase, the erase speed can be well controlled for cells with different channel lengths and a wide range of program-state Vt distribution, which will reduce overerasure significantly.
A novel fully CMOS process compatible PREM for SOC applications
(2005-03-01)
Yeh, CC
;
Wang, TH
;
Tsai, WJ
;
Lu, TC
;
Liao, YY
A novel nonvolatile memory cell named programmable resistor with eraseless memory (PREM) is proposed for system on chip applications for the first time. PREM combines a novel "eraseless" algorithm and the progressive breakdown of an ultrathin oxide. No or one extra mask is needed with a standard CMOS process. Multitime programming, multilevel cell, nonvolatility, and low-voltage operation are realized. Good reliability is demonstrated based on the result of a single cell.
A novel PHINES flash memory cell with low power program/erase, small pitch, two-bits-per-cell for data storage applications
(2005-04-01)
Yeh, CC
;
Wang, TH
;
Tsai, WJ
;
Lu, TC
;
Chen, MS
A novel programming by hot-hole injection nitride electron storage (PHINES) Flash memory technology is-developed. The memory bit size of 0.046 mu m(2) is fabricated based on 0.13-mu m technology. PHINES cell uses a nitride trapping storage cell structure. Fowler-Nordheim (FN) injection is performed to raise V-t in erase while programming is done by lowering a local V-t through hand-to-hand tunneling-induced hot hole (BTBT HH) injection. Two-bits-per-cell feasibility, low-power and high-speed program/erase, good endurance and data retentivity make it a promising candidate for Flash EEPROM technology in gigabit era applications.
A novel soft-program for a narrow erased state Vt distribution, read disturbance suppression and over-program annihilation in multilevel cell flash memories
(2003-04-01)
Yeh, CC
;
Fan, TH
;
Lu, TC
;
Wang, TH
;
Pan, S
In floating gate flash memories, anode hot hole injection induced by the channel FN erase will result in tunnel oxide, degradation, severe read disturbance and an abnormally fast program. All of these issues are critical for multilevel cell (MLC) flash memory design, which requires precise threshold voltage placement, good data retentivity and programming controllability. In this paper, a novel soft-program scheme is proposed to narrow the threshold voltage distribution in the first level. Cycling-induced read disturbance and programming inaccuracy are also reduced. This technique is essential for the application of more-than-2-bit MLC, flash memories.
Design of microstrip bandpass filters with a dual-passband response
(2005-04-01)
Kuo, JT
;
Yeh, TH
;
Yeh, CC
;
電信工程研究所
;
Institute of Communications Engineering
This paper presents a rigorous design of microstrip bandpass filters with a dual-passband response in parallel-coupled and vertical-stacked configurations. Based on resonance characteristics of a stepped impedance resonator (SIR), the second resonant frequency can be tuned over a wide range by adjusting its structure parameters. Emphasis is placed on filter synthesis for simultaneously matching in-band response and singly loaded Q by using tapped input/output couplings for the two designated passbands. Fractional bandwidth design graphs are used to determine proper geometric parameters of each coupled stage when filter specification is given. Realizable fractional bandwidths of the two passbands for a coupled SIR structure are clearly depicted in fractional bandwidth design graphs. Several experimental litters are fabricated and measured to demonstrate the design.
Factors affecting the safety performance of bus companies - The experience of Taiwan bus deregulation
(2005-06-01)
Chang, HL
;
Yeh, CC
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
This study was undertaken to explore the factors affecting the safety performance of bus companies in Taiwan. A conceptual framework was developed based on the theory of organizational accidents. Environmental and organizational factors were assumed to determine the safety performance of bus companies. Since the deregulation of intercity passenger transportation in 1995 the bus transportation industry in Taiwan has been restructured, and this provides an opportunity to gain insight into the factors that influence the safety performance of bus companies. The study results show that the bus companies on joining intercity bus services in Taiwan did experience higher risks of being involved in major injury and minor injury accidents. The study results provide convincing evidence that organizational factors, including driver-specific, vehicle-specific and general management factors, have significant effects on the safety performance of bus companies. Therefore, if the economic deregulation was implemented with some safety regulation policies, we might have the opportunity to pursue a better safety performance by the bus transport industry as a whole, rather than just prevent the deterioration of the existing safety performance. Furthermore, the limited resources available to monitor the safety performance of bus companies are suggested to focus on those companies that run intercity services as well as those companies of small size, having older fleets, and a higher traffic conviction rate. (c) 2005 Elsevier Ltd. All rights reserved.
Investigation of programmed charge lateral spread in a two-bit storage nitride flash memory cell by using a charge pumping technique
(2004)
Gu, SH
;
Wang, MT
;
Chan, CT
;
Zous, NK
;
Yeh, CC
The lateral distribution of programmed charge in a hot electron program/hot hole erase nitride storage flash cell is investigated by using a charge pumping technique. Our study shows that the secondly programmed bit has a wider trapped charge distribution than the first programmed bit. In addition, we find prograrnmed charge spreads further into the channel with program/erase cycle number.
Positive oxide charge-enhanced read disturb in a localized trapping storage flash memory cell
(2004-03-01)
Tsai, WJ
;
Yeh, CC
;
Zous, NK
;
Liu, CC
;
Cho, SK
Read disturb-induced erase-state threshold voltage instability in a localized trapping storage Flash memory cell with a poly-silicon-oxide-nitride-oxide-silicon (SONOS) structure is investigated and reported. Our results show that positive trapped charge in bottom oxide generated during program/erase (P/E) cycles play a major role. Both gate voltage and drain voltage will accelerate the threshold voltage (V-t) drift. Hot-carrier caused disturb effect is more severe in a shorter gate length device at low temperature. A model of positive charge-assisted electron tunneling into a trapping nitride is proposed. Influence of channel doping on the V-t drift is studied. As the cell is in an "unbiased" storage mode, tunnel detrapping of positive oxide charges is responsible for the threshold voltage shift, which is insensitive to temperature.
Role of positive trapped charge in stress-induced leakage current for flash EEPROM devices
(2002-11-01)
Wang, TH
;
Zous, NK
;
Yeh, CC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The transient behavior of hot hole (HH) stress-induced leakage current (SILC) in tunnel oxides is investigated. The dominant SILC mechanism is positive oxide charge-assisted tunneling (PCAT). The transient effect of SILC is attributed to positive oxide charge detrapping and thus the reduction of PCAT current. A correlation between SILC and stress-induced substrate current is observed. Our study shows that both SILC and stress-induced substrate current have power law time-dependence t(-n) with the power factor n about 0.7 and 1, respectively. Numerical analysis for PCAT current incorporating a trapped charge caused Coulombic potential in the tunneling barrier is performed to evaluate the time-and field-dependence of SILC and the substrate current. Based on our model, the evolution of threshold voltage shift with read-disturb time in a Flash EEPROM cell is derived. Finally, the dependence of SILC on oxide thickness is explored. As oxide thickness reduces from 100 Angstrom to 53 Angstrom, the dominant SILC mechanism is found to change from PCAT to neutral trap-assisted tunneling (TAT).
Site characterization of a dynamically compacted silty fine sand
(1998)
Huang, AB
;
Chang, JW
;
Chen, DDS
;
Yeh, CC
;
土木工程學系
A reclaimed land of approximately 2400 hectares is under construction as part of an industrial development at Mail Liao Township, on the West Coast of Taiwan. Silty fine sand dredged offshore was placed hydraulically to reach a final grade of 3 m above sea level. The foundation soil consists of similar material that extends to several hundred meters below sea level. The new sand fill and the underlying foundation soil was dynamically compacted to increase the sand density within top 10 m. Earlier attempts to estimate pile shaft frictions using CPT data according to existing methods were 30 to 70% below those measured in pile load tests at Mai Liao. A new method to predict the shaft friction that considers the characteristics of the silty fine sand at Mai Liao and the effects of dynamic compaction is proposed. The new method was developed based on a series of laboratory experiments that include CPT chamber calibration tests. According to comparisons with four pile load tests, the new method provides a reasonable and slightly conservative prediction for the shaft friction of driven PC piles. The average error was - 12%.
The life cycle of the policy for preventing road accidents: an empirical example of the policy for reducing drunk driving crashes in Taipei
(2004-09-01)
Chang, HL
;
Yeh, CC
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
The purpose of this paper is to examine the temporal variation of the effect of preventive policy on reducing traffic accidents. The life cycle theory was introduced to describe the safety effect of the intervening policy over time. Poisson regression models with dummy-based and time-based specifications were used to evaluate the effect of an intervening policy over an observation period following its implementation. The policy of "Criminal sanction for drunk driving (CSFDD)" in Taipei city was evaluated as an empirical example to determine whether the temporal variation of safety effect happened to the CSFDD policy. The study results showed that alcohol consumption, arresting the drunk driving offenders, and the implementation of the CSFDD were the significant factors affecting the rate of occurrence of fatal accidents involving drunk driving. The effect of the CSFDD policy appeared to be a rapid initial response followed by a lowerrate of decay. The existence of the life cycle implies that employing different observation periods following the implementation of a specific policy to evaluate its performance may obtain different effects. The results of this study are crucial for policy evaluation. The effects of safety policy should be carefully interpreted in order to avoid misleading the relevant authorities in coming to the wrong conclusions and as such make the wrong decisions. 9 (C) 2003 Elsevier Ltd. All rights reserved.
The relationship between the working pressure and accident risks for aggregate-hauling vehicle drivers in Taiwan
(2001)
Chang, HL
;
Yeh, CC
;
運輸與物流管理系註：原交通所+運管所
;
Department of Transportation and Logistics Management
This study is undertaken to explore the sources of stress which enhance the accident risk of AHV drivers and try to develop corresponding strategies to improve the driving safety for AT-TV drivers. In this paper, we introduce the relationship between work pressure and accident risk and develop a conceptual model based on this relationship. An empirical study was conducted by using the data collected from a face to face interview with AHV drivers to verify our hypothetical relationship. The findings of this study provide a set of valuable information to help setting effective policies and strategies.
The Taiwan system of innovation in the tool machine industry: a case study
(2003-12-01)
Yeh, CC
;
Chang, PL
;
經營管理研究所
;
Institute of Business and Management
Recent evidence suggests that the Taiwan's machine tool industry as a whole is prominent in the world, ranking sixth in output and fifth in exports. This paper explores the current status and features of Taiwan's national systems of innovation (NSI) for its machine tool industry. It is suggested that five major elements of the NSI explain the extensive diffusion of new technologies in the industry, namely: industry clusters, educational system, bridging institutions, government policy, and global business environment. Further, the structural and institutional problems of the innovation system are identified. Future directions of technology development are also discussed. (C) 2003 Elsevier B.V. All rights reserved.
Transient effects of positive oxide charge on stress-induced leakage current in tunnel oxides
(1999-08-02)
Zous, NK
;
Wang, TH
;
Yeh, CC
;
Tsai, CW
;
Huang, CM
The role of positive oxide charge in excess low-level leakage current in tunnel oxides induced by Fowler/Nordheim stress is investigated. A correlation between stress-induced gate current and substrate current in an n-channel metal-oxide-semiconductor field-effect transistor is observed. Both the gate current and the substrate current exhibit a significant transient effect. The mechanisms of the stress-induced currents and their field dependence are explored. Positive oxide charge tunnel detrapping is found to be the cause of the observed transient behavior in the two currents. The stress-created positive oxide charge can be significantly annealed by substrate hot electron injection. (C) 1999 American Institute of Physics. [S0003-6951(99)02226-3].