Browsing by Issue Date, starting with "2002-07-01"

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A multiprocess performance analysis chart based on the incapability index C-pp: an application to the chip resistors
(2002-07-01)
Pearn, WL
;
Ko, CH
;
Wang, KH
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Statistical process control charts, such as the (X) over bar, R, S-2, S, and MR charts, have been widely used in the manufacturing industry for controlling/monitoring process performance, which are essential tools for any quality improvement activities. Those charts are easy to understand, which effectively communicate critical process information without using words and formula. In this paper, we introduce a new control chart, called the C-pp multiple process performance analysis chart (MPPAC), using the incapability index C-pp. The C-pp MPPAC displays multiple processes with the departure, and process variability relative to the specification tolerances, on one single chart. We demonstrate the use of the C-pp MPPAC by presenting a case study on some resistor component manufacturing processes, to evaluate the factory performance. (C) 2002 Elsevier Science Ltd. All rights reserved.
A simple remote user authentication scheme
(2002-07-01)
Hwang, MS
;
Lee, CC
;
Tang, YL
;
資訊工程學系
;
Department of Computer Science
In this article, we propose a simple remote user authentication scheme using smart cards. This scheme has the following features. First, it does not require any password or verification tables. Second, it can withstand the message replay attack. Third, any legal users can arbitrarily choose and change their own passwords at will. And finally, the password of a user is not revealed to the server. In addition, the computational costs of this scheme are less than those of any previously proposed schemes. (C) 2002 Elsevier Science Ltd. All rights reserved.
Solutions of semilinear elliptic equations with asymptotic linear nonlinearity
(2002-07-01)
Hsu, CH
;
Shih, YW
;
應用數學系
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Department of Applied Mathematics
Structure effects on electron-optical phonon interaction in GaAs/AlxGa1-xAs quantum wells
(2002-07-01)
Lee, HC
;
Sun, KW
;
Lee, CP
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Based on the dielectric continuum model, we have studied the electron-optical phonon scattering rates in GaAs/AlxGa1-xAs quantum wells with different structure parameters. It was found that the scattering rate of the symmetric interface phonon mode has a stronger dependence on the Al composition in the barriers than that of the confined mode. The effective phonon energy emitted by hot electrons in GaAs/AlxGa1-xAs quantum wells with various Al compositions was estimated and the calculated value agrees with the experimental results qualitatively. For the dependence on the well width, scattering rates of the S+ mode drop considerably as the well width is increased. The dependence of the electron-optical phonon interaction on structure parameters can be clearly explained by the H and G factors defined in the article. (C) 2002 American Institute of Physics.
Formation of self-assembled ZnTe quantum dots on ZnSe buffer layer grown on GaAs substrate by molecular beam epitaxy
(2002-07-01)
Kuo, MC
;
Yang, CS
;
Tseng, PY
;
Lee, J
;
Shen, JL
Self-assembled ZnTe quantum dot structures were grown by molecular beam epitaxy on GaAs substrates with a 200 nm ZnSe buffer layer. Surface morphology was studied by atomic force microscopy. A three-dimensional Volmer-Weber growth mode was identified. Two types of dots were observed. Strong photoluminescence observed at 1.9-2.2 eV was attributed to emission from the large type II ZnTe quantum dots. Emission from the smaller ZnTe quantum dots was observed at an energy of around 2.26 eV. The density of the larger and smaller dots was approximately 10(8)/cm(2) and 10(9)/cm(2), respectively. (C) 2002 Elsevier Science B.V. All rights reserved.
A new process-variation-immunity method for extracting capacitance coupling coefficients in flash memory cells
(2002-07-01)
Cho, CYS
;
Chen, MJ
;
Lin, JH
;
Chen, CF
;
電子工程學系及電子研究所
Overestimation of capacitance coupling coefficients in flash memory cells is encountered in the subthreshold slope method. By means of a two-parameters subthreshold current model I-D = I-o exp[q(V-GB - nV(SB))/nkT], a mathematical formulation of the subthreshold swing ratio in the subthreshold slope method is constructed to isolate the measurement errors caused by process variations from the errors traditionally caused by bulk capacitance coupling. To minimize the effect of process variations, a new method is developed based on the model. In this method, the control gate voltage shift due to weak body effect is measured in flash memory cells in subthreshold, while the corresponding slope factor n is adequately deduced from threshold voltage versus source-to-substrate bias measurement in dummy devices. The corrected capacitance coupling coefficients show large improvements compared to the design values, and the updated errors are found to be close to that caused solely by bulk capacitance coupling. The method is also fast since only a small source-to-substrate bias of 0.1 V is needed for implementation of weak body effect, and thereby it can be used as an in-line monitor of capacitance coupling coefficients.
Method for determining the optical axis and (n(e), n(o)) of a birefringent crystal
(2002-07-01)
Su, DC
;
Hsu, CC
;
光電工程學系
;
Department of Photonics
There is a phase difference between s and p polarizations when a circularly polarized heterodyne light beam is reflected from a birefringent crystal. It can be measured accurately with a common-path heterodyne interferometric technique. We have derived an equation that describes the relationship between the phase differences and n(e) n(o), and alpha. Two groups of solutions for (n(e), n(o)) can be obtained from this equation by the phase measurements performed at three incident angles under moderate conditions. Each group consists of three pairs of solutions for (n(e), n(o)). Finally, by justifying with physical conditions, we obtained the correct solution for (n(e), n(o)). Azimuth angle alpha of the birefringent crystal optical axis can also be determined. And the feasibility of this method is demonstrated. (C) 2002 Optical Society of America.
Reduction of etching plasma damage on low dielectric constant fluorinated amorphous carbon films by multiple H-2 plasma treatment
(2002-07-01)
Shieh, JM
;
Tsai, KC
;
Dai, BT
;
Wu, YC
;
Wu, YH
Two-step hydrogen plasma treatment on low dielectric constant (low-k) fluorinated amorphous carbon films (a-C:F) was conducted to improve their thermal stability and reduce the damage caused by the patterning processes. First, hydrogen plasma treatment repairs imperfect bonds of as-deposited a-C:F films, stabilizing their chemical structures and increasing their resistance against elevated thermal stresses. After this passivation process, an additional hydrogen plasma treatment was applied to a-C:F films that had been etched using a mixture of N-2+O-2+CHF3, enabling sub-130 nm damascene trenches to be patterned and repairing the chemical structures destroyed by the etching plasma. (C) 2002 American Vacuum Society.
Synthesis of alkyl-branched main chain copolyimides and their effect on the pretilt angles of liquid crystal alignment
(2002-07-01)
Lee, WC
;
Chen, JT
;
Hsu, CS
;
Wu, ST
;
應用化學系
Three series of copolyimides containing long alkyl branches were synthesized using the two-step method via poly(amic acid) precursors and chemical imidization. Most of the copolyimides prepared are soluble in polar organic solvents. Good liquid crystal alignment was achieved by buffing the copolyimide films spin-coated onto indium tin oxide glass substrates. The measured liquid crystal pretilt angles range from 0.16degrees to 15.54degrees. The Titan simulation program was used to calculate the dipole of each dianhydride structure and correlate with the observed pretilt angles. Main chain copolyimides with a long alkyl side chain, small dipole, and linear, symmetric and rigid core structures are favourable for generating large pretilt angles.
Charge pumping profiling technique for the evaluation of plasma-charging-enhanced hot-carrier effect in short-N-channel metal-oxide-semiconductor field-effect transistors
(2002-07-01)
Chen, SJ
;
Chung, SSS
;
Lin, HC
;
電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Plasma etching of poly-silicon in a metal-oxide-semiconductor field-effect transistor (MOSFET) during the gate definition process induces edge damage at the gate-drain overlap edge. This edge damage will be further enhanced by the antenna effect and cause a more serious hot-carrier (HC) effect, particularly in short-channel devices. We call this phenomenon the plasma-charging-enhanced HC effect. In this paper, this plasma-charging-enhanced HC effect is evaluated by the charge pumping (CP) profiling technique, in which the enhanced damage at the gate-drain overlap gate oxide region can be identified. A three-phase plasma damage mechanism is then proposed to explain the observed effect. According to experimental results, it was shown that the interface traps generated at the gate-drain overlap edge are mainly attributed to the plasma-charging-enhanced HC effect. These interface traps (Nit) become the dominant mechanism of the drain current (ID) degradation, which increases with a reducing channel length (L). Again, the enhanced HC-effect-induced-degradation will dominate the device reliability under long-term operations.
Sensation seeking and internet dependence of Taiwanese high school adolescents
(2002-07-01)
Lin, SSJ
;
Tsai, CC
;
師資培育中心
;
Center of Teacher Education
The present study examined excessive Internet use of Taiwanese adolescents and a psychological aspect of users. sensation seeking, thus to differentiate motivation of Internet dependents and non-dependents. Seven hundred and fifty three Taiwanese high school student, were selected using cluster sampling and 88 of them were categorized as Internet dependent users. Results indicated that Internet dependents spent more time on-line than non-dependents. While Internet dependents perceived significantly more negative Internet influences on daily routines, school performance. and parental relation than non-dependents, both Internet dependents and non-dependents viewed Internet use as enhancing peer relations. Making friends through the Internet has become a popular activity among adolescents, Potentially leading to its excessive use. Internet dependents scored significantly higher on overall sensation seeking and disinhibition than Internet non-dependents. Ho ever. both groups did not differ in the life experience seeking subscale and thrill and adventure seeking subscale. This finding contradicts that of Lavin, Marvin. McLarney, Nola. and Scott [CyberPsychol. Behav. 2 (2000) 425], Possible reasons for this discrepancy and for the relation between Internet dependence and disinhibition in Taiwanese adolescents are also discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.
Subgrouping small states based on socioeconomic characteristics
(2002-07-01)
Liou, FM
;
Ding, CG
;
交大名義發表
;
National Chiao Tung University
Developing small states are often discussed as a whole because of shared vulnerabilities, but could instead be treated according to their different socioeconomic characteristics. This paper investigates those differences and subgroups them through the use of statistical methods. Seven common factors were first extracted from 25 key socioeconomic indicators. Cluster analysis based on factor scores was then used to obtain distinct clusters of small states. Nine well-delineated clusters were thus obtained, each of which containing small states with similar characteristics, Managerial implications for international aid based on the findings are then proposed. (C) 2002 Elsevier Science Ltd. All rights reserved.
Eliminating dielectric degradation of low-k organosilicate glass by trimethylchlorosilane treatment
(2002-07-01)
Chang, TC
;
Liu, PT
;
Mor, YS
;
Tsai, TM
;
Chen, CW
The interaction between low-k organosilicate glass (OSG) and photoresist removal is investigated. O-2 plasma ashing and chemical wet stripper are commonly performed to remove photoresist (PR) in integrated circuit fabrication. However, O-2 plasma or wet stripper will attack function groups and cause Si-OH group formation in OSG film during PR removal processing. The Si-OH groups often lead to moisture uptake and consequently dielectric degradation will occur in OSG film. Trimethylchlorosilane (TMCS) treatment can negate the damage in the OSG film after the PR removal process. In addition, chemical TMCS can react with Si-OH groups and reduces moisture uptake so that the dielectric characteristic of OSG can be maintained. Hence, TMCS treatment is a promising method for photoresist removal. (C) 2002 American Vacuum Society.
A numerical investigation of effects of a moving operator on airflow patterns in a cleanroom
(2002-07-01)
Yang, SJ
;
Fu, WS
;
機械工程學系
;
Department of Mechanical Engineering
The variations of the airflow induced by a moving operator in a cleanroom installed with a curtain were studied numerically. This situation is cataloged to a class of the moving boundary problems. An arbitrary Lagrangian-Eulerian kinematic description method is utilized to describe the flow field and a penalty finite element formulation with moving meshes is adopted to solve this problem. The effects of the moving operator and curtain on the airflow patterns under different distances from the workbench to the curtain with the moving speed of the operator equal to 2.0 and Reynolds number Re = 500 are taken into account. The results show that recirculation zones are formed around the operator and workbench due to the movement of the operator. The recirculation zones are not favorable to the cleanroom because they may induce a local turbulent flow and entrain and trap contaminants. These phenomena are remarkably different from those of the moving operator assumed as stationary in the cleanroom. Based on the length of the curtain, it is useful for protecting the operator from the hazardous gases. (C) 2002 Elsevier Science Ltd. All rights reserved.
Novel I-line phase shift mask technique for submicron T-shaped gate formation
(2002-07-01)
Chen, SH
;
Chang, HC
;
Fu, DK
;
Chang, EY
;
Lai, YL
A novel submicron (<0.2 mum) T-shaped gate technology using a phase shift mask (PSM) technique is developed. The 8% half-tone PSM was selected for the definition of the isolated narrow space. Before lithography, a 2000 Angstrom SiN film was deposited on the wafer. After i-line PSM exposure and reactive ion etching (RIE) of the silicon nitride film, openings less than 0.2 mum wide were formed on the SiN film. To further reduce the dimensions of the openings, an additional 566 Angstrom nitride was then deposited on the wafer and etched back using RIE without any mask. An opening of 0.167 mum was formed on the wafer after the dry etching process. The wafer was then coated with another layer of photoresist to form a lift-off structure. The T-shaped gate with a length of 0.167 mum was obtained using this technique. The novel T-shaped gate technology is a high-throughput process for both silicon and compound semiconductor devices.
An adaptive measured-based preassignment scheme with connection-level QoS support for mobile networks
(2002-07-01)
Luo, XY
;
Li, B
;
Thng, ILJ
;
Lin, YB
;
Chlamtac, I
This paper presents a new adaptive bandwidth allocation scheme to prevent handoff failure in wireless cellular networks, known as the measurement-based preassignment (MPr) technique. This technique is particularly useful in micro/pico cellular networks which offers quality-of-service (QoS) guarantee against call dropping: The proposed MPr scheme distinguishes itself from the well-known guarded channel (GC) based schemes in that it allows the handoff calls to utilize a prereserved channel. pool before competing for the shared channels with new call arrivals. The key advantage of the proposed MPr scheme is that it enables easy derivation of the number of channels that needs to be reserved for handoff based on a predetermined handoff dropping probability, without the need for solving the often complex Markov chain required in GC schemes; thus, making the proposed MPr scheme-simple and efficient for implementation. This is essential in handling multiple traffic types with potentially different QoS requirements. In addition, the MPr scheme is adaptive in that it can dynamically adjust the number of reserved channels for the handoff according to the periodical measurement of the traffic status within a local cell; thus completely eliminating the signaling overhead for status information exchange among cells mandated in most existing channel allocation schemes. Numerical results and comparisons are given to illustrate the tradeoff.
An efficient and stable ray tracing algorithm for parametric surfaces
(2002-07-01)
Wang, SW
;
Shih, ZC
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
In this paper, we propose an efficient and stable algorithm for finding the ray-surface intersections. Newton's method and Bezier clipping are adapted to form the core of our algorithm. Ray coherence is used to find starting points for Newton iteration. We introduce an obstruction detection technique to verify whether an intersection point found by using Newton's method is the closest one. When Newton's method fails to achieve convergence, we use Bezier clipping as the substitution to find the intersection points. This combination achieves significant improvement in tracing primary rays. A similar approach also successfully improves the performance in tracing secondary rays.
Computer program for calculating the p-value in testing process capability index C-pmk
(2002-07-01)
Pearn, WL
;
Lin, PC
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
Many process capability indices, including C-p, C-pk, and C-pm, have been proposed to provide numerical measures on the process potential and performance. Combining the advantages of these indices, Pearn et al. (1992) introduced a new capability index called C-pmk, which has been shown to be a useful capability index for processes with two-sided specification limits. In this paper, we implement the theory of a testing hypothesis using the natural estimator of C-pmk, and provide an efficient Maple computer program to calculate the p-values. We also provide tables of the critical values for some commonly used capability requirements. Based on the test we develop a simple step-by-step procedure for in-plant applications. The practitioners can use the proposed procedure to determine whether their process meets the preset capability requirement, and make reliable decisions. Copyright (C) 2002 John Wiley Sons, Ltd.
Numerical investigation of heat transfer from a heated oscillating cylinder in a cross flow
(2002-07-01)
Fu, WS
;
Tong, BH
;
機械工程學系
;
Department of Mechanical Engineering
A numerical simulation is performed to study the flow structures and heat transfer characteristics of a heated transversely oscillating cylinder in a cross flow. The variations of flow and thermal fields are classified into a class of moving boundary problems. The moving interfaces between the fluid and cylinder have been considered. An arbitrary Lagrangian-Eulerian kinematic description method is adopted to describe the flow and thermal fields. A penalty consistent finite element formulation is applied to solve the governing equations. The subsequent developments of the vortex shedding and heat transfer characteristics around the heated cylinder are presented in detail. The effects of Reynolds number, oscillating amplitude, oscillating speed on the flow structures and heat transfer characteristics are examined. The results show that the interaction between the oscillating cylinder and vortex shedding from the cylinder dominates the state of the wake. The flow and thermal fields may approach a periodic state in lock-in regime. The heat transfer of the cylinder in the lock-in regime is enhanced remarkably. (C) 2002 Published by Elsevier Science Ltd.
Low-voltage cathodoluminescence properties of the Y2O2S : Eu red light emitting phosphor screen in field-emission environments
(2002-07-01)
Lo, CL
;
Duh, JG
;
Chiou, BS
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Y2O2S: Eu phosphors doped with different concentrations of Eu were fabricated by a high-temperature flux fusion method. For applications in field emission displays, phosphor powders were electrophoretically deposited on an indium-tin oxide coated glass substrate to form a phosphor screen. Cathodoluminescence properties of phosphor screens were examined at a low excitation voltage of 5 kV in a high-vacuum chamber (5 x 10(-8) Torr), and characteristics of Y2O2S: Eu phosphors, including brightness and wavelength data, are presented and discussed. The red emission brightness for the Y2O2S: Eu phosphor screens can be significantly improved by adjustment of the Eu additions, which decrease the x coordinate slightly, while having no significant influence on the color performance. Considering the effects of Eu concentrations on red light emission spectra and brightness for Y2O2S: Eu phosphor screens, it is found that brightness for Y2O2S: Eu phosphor screens could be obtained up to 120 cd/m(2) with chromaticity of x = 0.63 and y = 0.36, and the Eu dopant concentration is suggested to be in the range 6-7.5 wt %. (C) 2002 The Electrochemical Society.