Browsing by Author "Ko, CH"

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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
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Ko, CH
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Wang, KH
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工業工程與管理學系
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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.
Channel backscattering characteristics of strained PMOSFETs with embedded SiGe source/drain
(2005)
Lin, HN
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Chen, HW
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Ko, CH
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Ge, CH
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Lin, HC
Channel backscattering ratios of PMOSFETs with various embedded SiGe source/drain structures are analyzed in terms of the scattering theory We found that both the backscattering ratio and injection velocity are greatly influenced by the location and recess depth of SiGe source/drain. Although the strain-enhanced injection velocity is beneficial to the current gain, the accompanying backscattering ratio increase adversely impacts the overall performance, and therefore a trade-off exists between injection velocity and backscattering ratio during the optimization of such strain technique. The mechanism of increased backscattering ratio under uniaxial compressive strain is also investigated.
Channel backscattering characteristics of uniaxially strained nanoscale CMOSFETs
(2005-09-01)
Lin, HN
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Chen, HW
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Ko, CH
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Ge, CH
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Lin, HC
Channel backscattering characteristics of uniaxially strained nanoscale CMOSFETs are reported for the first time. Channel backscattering ratio increases and decreases under uniaxial tensile and compressive strain, respectively. It is found that in sub-100-nm devices, strain-induced modulation of carrier mean-free path for backscattering and reduction in kBT layer thickness are responsible for the different behaviors of backscattering ratio. Nevertheless, the source-side injection velocity improves irrespective of the strain polarities. The impact of channel backscattering ratio on drive current is also analyzed in terms,of ballistic efficiency and injection velocity.
Energy-tunable transmission x-ray microscope for differential contrast imaging with near 60 nm resolution tomography
(2006-06-12)
Yin, GC
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Tang, MT
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Song, YF
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Chen, FR
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Liang, KS
An energy-tunable transmission hard x-ray microscope with close to 60 nm spatial resolution in three dimensions (3D) has been developed. With a cone beam illumination, a zone plate of 50 nm outmost zone width, a stable mechanical design, and software feedback, we obtained tomographic data sets that are close to 60 nm spatial resolution. Meanwhile, the element specific imaging was also obtained by a differential absorption contrast technique used below and above the absorption of the element. Examples of advanced intergraded circuit devices are used to demonstrate the element selectivity and spatial resolution in 3D of the microscope.
Fuzzy macromodel for dynamic simulation of microelectromechanical systems
(2006-07-01)
Ko, CH
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Chiou, JC
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper proposes an efficient approach that consists of an experimental design and a fuzzy-logic model (FLM) to generate macromodels for the simulation of microelectromechanical systems. Firstly, in the present approach, a force macromodel is adapted to perform the coupled simulations. Then, an experimental design is utilized to reduce the number of data needed for macromodel identification, and an FLM is chosen to fit the data. The identification scheme involves cluster estimation to determine the FLM structure and backpropagation method to efficiently obtain the FLM structure parameters that lead to an accurate macromodel. In order to verify the accuracy of the macromodel, the approach has been applied to a magnetic microactuator. The simulation results show that the force macromodel yielded errors of less than 1.5% for a 5-mu m displacement. Furthermore, the dynamic coupled simulation takes only several minutes. The results demonstrate the efficiency and effectiveness of the current approach.
Magnetic analysis of a micromachined magnetic actuator using the finite element method
(1999)
Ko, CH
;
Yang, JJ
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Chiou, JC
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Chen, SC
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Kao, TH
In this paper, a parametrical method is developed to design a magnetic microactuator. The method is based on modeling the magnetic microactuator using the finite element analysis software that can be used to calculate the energy density and magnetic force. Here, the concept of design on experiments (DOE) is used to identify critical parameters that affect the performances of the electromagnetic microactuator. Numerical simulation results from a series of DOE have indicated that the dimension of core and the magnetic material block have the influence on planar electromagnetic actuators. When the length of the magnetic components is equal to that of outer diameter of coil circuit, we obtain the best efficiency in magnetic force. Furthermore, when we increase the thickness of the magnetic materials block or shorten the distance between the coils and magnetic material block, the magnetic force will increase dramatically. In addition, we can achieve a great magnetic force when the combination ratio of the length of the core is half of the magnetic material block. Simulation results have shown that electromagnetic actuators with high aspect ratio planar coil could sustain higher electrical current that consequently increases the magnetic force. During the realistic fabrication, the thick resist patterning and electroplating technologies is used to fabricate:the above-mentioned electromagnetic microactuator. Experimental results indicated that the magnetic force follows closely to the simulation results.
Optimal design of the magnetic microactuator using the genetic algorithm
(2003-07-01)
Ko, CH
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Chiou, JC
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電控工程研究所
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Institute of Electrical and Control Engineering
This paper presents the,optimal design of the magnetic microactuator using the genetic algorithm. The magnetic microactuator is composed of an enclosed core and a permalloy plate to form a closed magnetic circuit. The present design allows the area of the magnetic poles to be optimally enlarged and achieve a maximum force generation. To obtain the optimal geometry and maximum force, the genetic algorithm (GA) which is a robust, stochastic search method modeled on the concept of natural section and evolution is proposed. To increase the search efficiency of the GA, strategies like population-elitist scheme, fitness scaling, and operator probability adaptations are used. The simulation results indicated that a dramatically improvement in generating magnetic force, that has the potential to enhance the actuating aspect in MEMS applications. (C) 2003 Elsevier Science B.V. All rights reserved.
S-band gain-clamped grating-based erbium-doped fiber amplifier by forward optical feedback technique
(2006-04-03)
Yeh, CH
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Lin, MC
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Huang, TT
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Hsu, KC
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Ko, CH
An S-band gain-clamped erbium-doped fiber amplifier module, employing a fiber Bragg grating to serve as a reflected element for lasing a saturated tone injected into the module by forward optical feedback method, is proposed and investigated experimentally. Moreover, the performance and behavior of the gain and noise figure in the proposed gain- clamped S-band fiber amplifier have also been discussed in the effectively wavelength range of 1478 to 1520 nm. (c) 2006 Optical Society of America.
The impact of uniaxial strain engineering on channel backscattering in nanoscale MOSFETs
(2005)
Lin, HN
;
Chen, HW
;
Ko, CH
;
Ge, CH
;
Lin, HC
The influence of uniaxial process-induced strain on carrier channel backscattering in nanoscale MOSFETs is reported for the first time. It is observed that the backscattering ratio can be reduced by uniaxial tensile strain while it is increased by uniaxial compressive strain mainly due to strain-induced modulation in mean-free-path for backscattering and slight decrease in k(B)T layer thickness. Nevertheless, both strain polarities improve source-side injection velocity because of reduced carrier effective mass. Impact to current drive under uniaxial strain is analyzed in terms of mean-free-path, k(B)T layer thickness, ballistic efficiency and injection velocity.
X-ray micromachining SU-8 resist for a terahertz photonic filter
(2005-04-07)
Shew, BY
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Li, HC
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Pan, CL
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Ko, CH
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機械工程學系
Deep x-ray lithography (DXL) was used to fabricate two-dimensional photonic crystals (PCs) for a terahertz high-pass filter. Instead of the conventional poly(methyl rnethacrylate) resist, high-sensitivity SU-8 resist was used to pattern the ultra-deep (1 mm), and high aspect ratio (> 30) PC structures. In this study, an x-ray mask with thick Si membrane was used in the DXL process owing to the high-sensitivity nature of SU-8. The robust mask structure can significantly improve the fabrication yield of the conventional x-ray mask with a very thin (< 2 mu m) membrane. Preliminary results demonstrate that SU-8 has poor pattern definition after DXL process, probably due to its high sensitivity. This phenomenon can be eliminated by dissolving oxygen into the resist to 'quench' the excessive photochemical reaction. Thanks to the high adhesion property of SU-8, the sticking problem of the high aspect ratio crystals is easily solved with natural drying by reducing the unbalanced capillary force. After optimizing all the processes. the proposed DXL SU-8 technique successively fabricated the terahertz crystals with high efficiency, high precision 1(< 1 mu m) and high surface quality (R(a) similar to 12 nm). The resist pillars were then deposited with a 300 nm thick gold layer for subsequent terahertz, measurement. The measurement results show that the PC structure acts as a high-pass filter in the terahertz, range. agreeing with the simulation results.