Browsing by Author "Wu, WC"

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A two-phase fault simulation scheme for sequential circuits
(1998-09-01)
Wu, WC
;
Lee, CL
;
Chen, JE
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A two-phase fault simulation scheme for sequential circuits is proposed. In this fault simulation, the input sequence is divided into two parts. In the first phase, fault free simulation is performed with the first sequence of patterns. In the second phase, fault simulation is performed with the rest of the patterns. Five cases of faults which result from two-phase fault simulation are discussed in detail. Significant speedup in simulation time can be obtained because this fault simulation approach can quickly drop Case 1 faults, which are time-consuming faults and would be considered undetectable in the traditional three-value fault simulation but are actually detected in exact fault simulation. Almost "exact" results can be obtained for detected faults except for a small percentage of over-detected-faults (ODFs) and under-detected-faults (UDFs).
An alternative interpretation of the magnetic penetration depth data on Pr2-xCexCuO4-y and La2-xCexCuO4-y
(2005-01-01)
Voo, KK
;
Wu, WC
;
電子物理學系
;
Department of Electrophysics
We have revisited the magnetic penetration depth data on the electron-doped cuprates, Pr2-xCexCuO4-y and La2-xCexCuO4-y. It is proposed that the transition between nodal-gap-like and nodeless-gap-like behavior upon electron-doping [e.g., see M. Kim et al., Phys. Rev. Lett. 91 (2003) 87001] can be due to a scattering of the quasiparticles in the d-wave superconducting state by an incipient or weak antiferromagnetic spin-density-wave. This conjecture is supported by the inelastic neutron scattering and angle-resolved photoemission experiments on some closely related electron-doped cuprates. (C) 2004 Elsevier B.V. All rights reserved.
An intelligent vision-based real-time integration system on autonomous vehicles
(2004)
Wu, BF
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Chiu, CC
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Chen, CJ
;
Wu, WC
;
Perng, JW
In this paper, an intelligent real-time system on autonomous vehicles is presented. A wireless-based remote control scheme is developed. A vision-based obstacle detection system and a radar sensor are integrated into the on-vehicle controller to automatically brake the vehicle under emergency. Finally, a successfully on-road demonstration is also completed with our experimental car. TAIWAN iTS-1.(1)
Characteristics of fluorine implantation for HfO2 gate dielectrics with high-temperature postdeposition annealing
(2006-04-01)
Lai, CS
;
Wu, WC
;
Wang, JC
;
Cha, TS
;
物理研究所
In this work, we describe the characteristics of silicon surface fluorine implantation (SSFI) for HFO2 films with high-temperature postdeposition annealing. The thermal stability of HfO2 gate dielectrics is much improved owing to the incorporation of fluorine into HfO2 thin films. The gate leakage current of the SSFI HfO2 films is about three orders less than that of samples without any fluorine implantation. In addition, improvements in stress-induced leakage current (SILC) and charge trapping characteristics are realized in the HfO2 films with the SSFI. The incorporation of fluorine atoms into the HfO2 films reduces not only interface dangling bonds but also bulk traps, which is responsible for the improvements in properties.
Characterization of CF4-plasma fluorinated HfO2 gate dielectrics with TaN metal gate
(2005-05-30)
Lai, CS
;
Wu, WC
;
Wang, JC
;
Chao, T
;
物理研究所
In this paper, fluorine incorporation into the HfO2 gate dielectrics by post CF4 plasma treatment was proposed to improve the electrical characterization. TaN-HfO2-p-Si capacitors were demonstrated in this work. The characteristics of fluorinated HfO2 gate dielectrics were improved, including the capacitance-voltage hysteresis and current-voltage behaviors. This may be attributed to the fluorine incorporated into the HfO2 gate dielectrics as revealed by secondary ion mass spectroscopy. Moreover, the formation of Hf-F bonding was observed through electron spectroscopy for chemical analysis spectra. (c) 2005 American Institute of Physics.
Crosstalk fault detection for interconnection lines based on path delay inertia principle
(2005)
Wu, MS
;
Lee, CL
;
Chang, YJ
;
Wu, WC
;
電子工程學系及電子研究所
The crosstalk fault becomes more and more important in the deep submicron SoC and its detection involves sophisticated timing measurement. In this paper a new test scheme to detect the crosstalk fault, based on the path delay inertia, for interconnection lines in SoC is proposed. The scheme, without using timing measurement, applies a transition on the aggressor line and a critical width pulse, CWP to the victim line and detects the propagation of the CWP at the output of the victim line. The scheme is simple and simulation analysis and experiments show that it is effective in detecting crosstalk faults.
Effects of post CF(4) plasma treatment on the HfO(2) thin film
(2005-04-01)
Lai, CS
;
Wu, WC
;
Fan, KM
;
Wang, JC
;
Lin, SJ
In this study, a novel approach was proposed to improve the characterization of HfO(2). Fluorine was incorporated by CF(4) plasma to improve the HfO(2) gate dielectric properties including leakage current, breakdown voltage and hysteresis. The hysteresis of capacitance-voltage characteristics can be reduced to approximately 10% hysteresis voltage for the samples with CF(4) plasma treatment. An inner-interface trapping model is presented to explain the hysteresis. The secondary-ion mass spectroscopy (SIMS) results show that there is a significant incorporation of fluorine (F) at the interface between the HfO(2) thin film and silicon substrate. The incorporation of F effectively suppressed leakage current and improved carrier trapping without an increase in interfacial layer thickness.
Fault diagnosis of odd-even sorting networks
(1997)
Hu, CW
;
Lee, CL
;
Wu, WC
;
Chen, JE
;
交大名義發表
This paper investigates detection and location for single faults in odd-even sorting networks. In the work, we have found that three tests are enough to locate single link fault and four tests are sufficient to detect single sorting element fault in an odd-even sorting network. For location tests for sorting element faults, the numbers of tests depend on the type of faults occurring at the sorting element. For most types of sorting element faults, the numbers are less than four specific tests. For the other types of faults, we have prevented the test generation procedure and binary search procedures to generate the tests. The numbers of location tests are less than (n+log(2)n), where n=log(2)N and N is the number of inputs of the sorting network.
Frequency-shaped sliding mode control for flying height of pickup head in near-field optical disk drives
(2005-02-01)
Wu, WC
;
Liu, TS
;
機械工程學系
;
Department of Mechanical Engineering
To achieve stable flying height of a pickup head in near-field optical disk drives, this study investigates a discrete sliding mode control with a frequency-shaped sliding surface. A compensator is introduced in a sliding mode using a frequency-shaped performance index with linear quadratic optimal and sliding mode control. As an actuator, a piezoelectric bender is used in this study to complement an air bearing at the head/disk interface. Experiments are carried out to demonstrate that the proposed controller performs better in flying height control than an optimal sliding mode controller. Accordingly, the controller can achieve stable flying height control in the presence of certain frequency vibration of optical disks.
Gold-free fully cu-metallized InGaP/GaAs heterojunction bipolar transistor
(2005-01-01)
Chang, SW
;
Chang, EY
;
Biswas, D
;
Lee, CS
;
Chen, KS
A gold-free, fully Cu-metallized InGaP/GaAs heterejunction bipolar transistor using platinum as the diffusion barrier has been successfully fabricated. The HBT uses Pd/Ge and Pt/Ti/Pt/Cu for n-type and p(+)-type ohmic contacts, respectively, and Ti/Pt/Cu for interconnect metals with platinum as the diffusion barrier. The Ti/Pt/Cu structure was stable during annealing up to 350degreesC judging from the X-ray diffraction (XRD) data and sheet resistance. A current-accelerated stress test was conducted on the device with a current density J(C) = 140 kA/cm(2) for 24 h, and the current gain showed no degradation. The devices were also thermally annealed at 250degreesC,for 24 h and showed little change. We have successfully demonstrated that an Au-free, fully Cu-metallized HBT can be realized using Pt as the diffusion barrier and Pd/Ge and Pt/Ti/Pt/Cu as the ohmic contacts.
Identification of robust untestable path delay faults
(1997-09-01)
Wu, WC
;
Lee, CL
;
Chen, JE
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents a theoretical analysis to identify robust untestable path delay faults. Firstly, it classifies the reconvergence of paths into seven cases and deduces the necessary conditions to robustly test path delay faults for each case. It then proposes a procedure, based on the deduced conditions, to identify the robust untestable path delay faults. The procedure is suitable for distributed processing by circuit partitioning to reduce the computation time and required memory. Experimental results on ISCAS 85' benchmark circuits show that the robust untestable faults occupy a high percentage of the total faults and high speedup can be obtained for distributed processing. In addition, it also presents a method to estimate the number of robust untestable path delay faults for a circuit.
Local density of states modulation and scanning tunneling microscopy in cuprate superconductors: Effect of gap anisotropy
(2005-06-01)
Wu, WC
;
Voo, KK
;
電子物理學系
;
Department of Electrophysics
Recent low-temperature Fourier-transformed scanning tunneling microscopy (FT-STM) data on optimally- and over-doped superconducting Bi2Sr2CaCu2O8 was shown to be an excellent manifestation of good quasiparticles in these samples. Along this line, we extend to study how the gap anisotropy effect can be investigated in the FT-STM images. The case of d(x2-y2)+s-wave gap, which may be relevant to YBa2Cu3O7-delta, is examined in details.
Microstructural evolution of Cu/Ta/GaAs multilayers with thermal annealing
(2004)
Wu, WC
;
Chen, CY
;
Lee, CS
;
Chang, EY
;
Chang, L
Copper metallization for GaAs was evaluated by using Cu/Ta/GaAs multilayers for its thermal stability. A thin Ta layer of 30 nm thickness was sputtered on the GaAs substrate as the diffusion barrier before copper film metallization. As judged from the results of sheet resistance, X-ray diffraction, Auger electron spectroscopy and transmission electron microscopy, the Cu/Ta films on GaAs were very stable up to 500 degreesC without Cu migration into GaAs. After 550 degreesC annealing, the interfacial mixing of Ta with GaAs substrate occurred, resulting in the formation of TaGa2 and TaAs2, and the diffusion of Ga and As through the Ta layer formed the Cu3Ga and Cu3As phases at the Cu/Ta interface. After 600 degreesC annealing, the reaction of GaAs with Ta and Cu formed TaAs and Cu3Ga, as a result of Cu migration and interfacial instability.
Oscillation ring delay test for high performance microprocessors
(2000)
Wu, WC
;
Lee, CL
;
Wu, MS
;
Chen, JE
;
Abadir, MS
This paper proposes a new test scheme, oscillation ring test, and its associated test circuit organization for delay fault testing for high performance microprocessors. For this test scheme, the outputs of the circuit under test are connected to its inputs to form oscillation rings and test vectors which sensitize circuit paths are sought to make the rings oscillate. High speed transition counters or oscillation detectors can then be used to detect whether the circuit is working normally or not. The sensitizable paths of oscillation rings cover all circuit lines, detecting all gate delay faults, a large part of hazard free robust path delay faults and all the stuck-at faults. It has the advantage of testing the circuit at the working speed of the circuit. Also, with some modification, the scheme can also be used to measure the maximum speed of the circuit. The scheme needs minimal simple added hardware, thus ideal for testing, embedded circuits and microprocessors.
Output feedback sliding mode control for the flying height of a pickup head in near-field optical disk drives
(2003-11-01)
Wu, WC
;
Liu, TS
;
機械工程學系
;
Department of Mechanical Engineering
An output sliding mode control method to produce a stable flying height for a pickup head in a near-field optical disk drive is presented. When the optical disks have a large amplitude vibration that makes a stable flying height difficult to attain, a piezoelectric bender is used to complement an air bearing at the head/disk interface. Control simulation for an identified model using measured vibration data of an optical disk is performed to demonstrate the robustness of the proposed method.
Parameter plane analysis of fuzzy control systems for limit cycle prediction
(2003)
Perng, JW
;
Wu, BF
;
Lee, TT
;
Wu, WC
;
電控工程研究所
The main purpose of this paper is to predict the limit cycles of fuzzy control system by combining the approaches of stability equation, describing function and parameter plane. The fuzzy controller is first linearized by using the describing function method. The stability of equivalent linearized system is. then analyzed by using stability equations and the parameter plane method. According to this procedure, the amplitude and frequency of limit cycles generated by the fuzzy controller can be figured out clearly in the parameter plane. In addition, both the continuous and sampled-data systems are considered. Finally, a fuzzy control system with multiple nonlinearities is also illustrated to verify its validity.
Sliding mode based learning control for track-following in hard disk drives
(2004-10-01)
Wu, WC
;
Liu, TS
;
機械工程學系
;
Department of Mechanical Engineering
This study aims to develop a sliding mode based learning controller for track-following in hard disk drives. The proposed controller incorporates characteristics of sliding mode control into learning control. The reason for using sliding mode control is attributed to its robust properties dealing with model uncertainty and disturbances. The learning algorithm utilizes shape functions to approximate influence functions in integral transforms and estimate the control input to reduce repetitive error. Mathematical derivation of the control law and stability analysis are presented. To validate the proposed method, this work conducts track-following experiments. (C) 2004 Elsevier Ltd. All rights reserved.
Sliding mode-based learning control for positioning of flying pickup head
(2001)
Liu, TS
;
Wu, WC
;
機械工程學系
;
Department of Mechanical Engineering
To deal with repetitive runout and disturbance in near-field optical disk drives, this study develops a sliding mode based learning controller. It incorporates characteristics of sliding mode control into learning control. The reason for using sliding mode control is attributed to robust properties dealing with model uncertainty and disturbances. The learning algorithm utilizes shape functions to approximate influence functions in integral transforms and estimate the control input to perform seeking movement. It learns at each sampling instant the desired control input without prior knowledge of system dynamics. To validate the proposed method, this work conducts track-seeking experiments.