Browsing by Author "Li, CH"

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A fast downsizing video transcoder based on H.264/AVC standard
(2004)
Li, CH
;
Wang, CN
;
Chiang, TH
;
交大名義發表
;
National Chiao Tung University
This paper presents a novel spatial transcoding technique for H.264/AVC based video applications. With superior coding performance, H.264 will be used in a variety of multimedia applications. For various video applications, spatial transcoding techniques can facilitate compact storage of video sequences with specified resolution and bitstrem format. Under demands, we can convert the archival bitstreams to another bitstream with different bitrates and different. resolution before transmission. For H.264 video transmission that needs spatial resolution conversion, we propose a bottom-up motion vector re-estimation, rapid rate-distortion (R-D) optimized mode decision. and adaptive motion search range to speed up the spatial transcoding and retain visual quality of transcoded video. The results show that the fast transcoder has the R-D performance close to or better than R-D re-encoding algorithm. which has the highest complexity and best coding efficiency.
A fast H.264-based picture-in-picture (PIP) transcoder
(2004)
Li, CH
;
Lin, H
;
Wang, CN
;
Chiang, T
;
電子工程學系及電子研究所
The paper presents a novel and fast transcoding scheme with PIP (Picture-in-Picture) functionality based on H.264/AVC standard. We seamlessly achieve significant speedup and maintain identical video quality for the composite video content using two H.264 bitstreams. The proposed Partial Re-Encoding transcoder (PRET) method based on the intra-prediction refinement, inter-prediction refinement and rate-distortion optimization has sped up by 8 times for with rate-distortion (R-D) based optimization. In addition, the performance of the PRET is better than that of R-D re-encoding algorithm.
A low complexity Picture-in-Picture transcoder for Video-on-Demand
(2005)
Li, CH
;
Wang, CN
;
Chiang, TH
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The paper presents a low complexity transcoding (LCT) approach with Picture-in-Picture (PIP) functionality based on H.264/AVC standard for Video-on-Demand (VOD) application. To address the high complexity of H.264 decoding and encoding tools, the novel and fast LCT approach composes a PIP frame in the transform domain based on an auxiliary bitstream. The auxiliary bitstream is generated along with the primary bitstream to provide the syntax elements including the transform coefficients and motion information for a rapid frame composition. To balance the transcoding speed and the Rate-Distortion (R-D) performance, the PIP transcoding with the auxiliary bitstream is applied to all inter-coded frames and the partially re-encoding transcoding, is used for the intracoded frames. By removing the high complexity g spatial interpolation, modules including motion compensation, in-the-loop deblocking filter and inverse spatial prediction from the transcoding process of all inter-coded frames, the LCT approach can significantly increase the transcoding throughput with very low memory requirement. Our experimental results show that the R-D performance of the LCT scheme is almost identical to that of the cascaded re-encoding approach, which can provide the theoretical best quality with highest complexity. In addition, the LCT approach that allows users to select the location and size of the foreground frame is applicable to the applications with interactive PIP service.
A new simple and reliable method to form a textured Si surface for the fabrication of a tunnel oxide film
(1998-05-01)
Chang, KM
;
Li, CH
;
Sheih, BS
;
Yang, JY
;
Wang, SW
In this work, a textured Si surface was formed with a new simple and reliable method for tunnel oxide fabrication. First, a thin poly-Si layer (12 nm thick) was deposited on Si surface and a 30-nm thick dry oxide film was then grown in O-2 ambient. This oxide film was served as a sacrificial oxide. The poly-Si film and Si substrate were both oxidized during thermal oxidization. After stripping this sacrificial oxide, a textured Si surface was obtained. Tunnel oxide grown on this textured Si surface has an asymmetrical J-E characteristics, less interface states generation and better reliability (larger Q(bd)) as compared to those of normal oxide.
A VBR rate control using MINMAX criterion for video streaming
(2002)
Li, CH
;
Wang, CN
;
Chiang, TH
;
資訊工程學系
;
電子工程學系及電子研究所
In this paper, we present a frame-level rate control scheme based on a modified linear Rate-Distortion model to achieve minimal maximum (MINMAX) distortion for frame-dependent quantizers. The MINMAX distortion measure is used because the worst visual quality often dominates the overall perceptual quality. In our approach, we first perform the iterative offline analysis of the rate-distortion behavior for the original sequences on a video server. Such compactly stored information enables the encoder to select quantization parameters in real-time during streaming process. Our results show that our algorithm obtains higher minimum PSNR values than the TM5 rate control while the average PSNR is similar. We also use the same technique to optimize statistical multiplexing for a multi-channel transmission application.
Biotrickling filtration for control of volatile organic compounds from microelectronics industry
(2003-07-01)
Den, W
;
Huang, CP
;
Li, CH
;
環境工程研究所
;
生物科技學系
This study investigated the transient and steady-state performance of a bench-scale biotrickling filter for the removal of an organic mixture (acetone, toluene, and trichloroethylene) typically emitted by the microelectronics industry. The, microbial consortium consisting of seven bacterial strains that were fully acclimated prior to inoculation onto activated carbon media. Among the seven strains, the Pseudomonas and Sphingomonas strains appeared to be the major groups degrading toluene (> 25 ppmv/h (.) 10(8) cell) and trichloroethylene (>2.3 ppmv/h. 10(8.) cell), while Mycobacteria and Acetobacteriaceae strains were the primary decomposers of acetone (> 90 ppmv/h (.) 10(8) cell). The column performance was evaluated by examining its responses to the fluctuating influent total hydrocarbon concentrations, which varied from 850 to 2,400 ppmv. Excellent steady-state removal efficiencies greater than 95% were consistently observed, and system recovery was typically within two days after a significant increase,in the inlet loading was experienced. The overall mass-transfer rate and the biokinetic constants were determined for each organic component. Mathematical simulations based on these parameters demonstrated that the removal of acetone was kinetically limiting, whereas the removals of toluene and trichloroethylene were. at least partially mass-transfer limiting.
Characteristics of selective chemical vapor deposition of tungsten on aluminum with a vapor phase precleaning technology
(1997-01-01)
Chang, KM
;
Yeh, TH
;
Wang, SW
;
Li, CH
;
電子工程學系及電子研究所
A simple and efficient precleaning of an aluminum surface with hydrochloric acid vapor prior to selective chemical vapor deposition of tungsten was investigated. The vapor phase precleaning was shown to remove the aluminum native oxide as well as reduce the aluminum fluorides formed at the W/Al interface during initial reaction of WF6 with the aluminum underlayer. It was found that the precleaning process is spontaneous and the removal rate of aluminum is related to the concentration of reactants used. After precleaning, the aluminum surface was free of oxide and covered with a large amount of Cl species that were examined by x-ray photoelectron spectroscopy. These Cl species occupy active sites on the wafer surface and prevent further adsorption of WF6 on the aluminum during the initial stage in selective deposition of tungsten. Therefore, the probability of reaction between WF6 and the underlying aluminum is greatly suppressed. By using a hydrochloric acid vapor to pretreat the aluminum trench and via hole patterned substrates, a smooth and dense tungsten film and low selectivity loss (<50 pcs/cm(2)) were obtained. A low concentration of aluminum fluorides accumulated at the W/Al interface that were involved in low via resistance was also observed.
Comprehensive study of plasma pretreatment process for thin gate oxide (<10 nm) fabricated by electron cyclotron resonance plasma oxidation
(1996-12-01)
Chang, KM
;
Li, CH
;
Fahn, FJ
;
Yeh, TH
;
Wang, SW
In this work, we comprehensively study the effect of ECR plasma pretreatment on ECR plasma grown SiO2 film. The ECR plasma grown gate oxide growth rate in the case of no plasma pretreatment is lower than that in the case of use of the plasma pretreatment step. Because the growth processes for these two methods (with and without pretreatment) differ only in terms of the initial surface conditions, the growth mechanisms are concluded to be determined by the initial Si surface conditions before plasma oxidation. The mid-gap interface states (Di(it-m)) of the ECR plasma grown SiO2 films in the case of plasma pretreatment are lower than those in the case of no plasma pretreatment. Through use of the plasma pretreatment process, the Si surface can be improved and cleaned before plasma oxidation. For SiO2 films pretreated with N-2 or Ar gas, the breakdown fields (E(bd)) are higher than those for SiO2 films not pretreated with N-2 or Ar gas. However, for NH3 gas pretreated films, the Ebd is lower than those for SiOz films pretreated with N-2 or Ar gas. This is because the NH3 gas contains H atoms which cause deterioration of F-N tunneling characteristics. Moreover, with the plasma pretreatment step, the stress-induced leakage currents (SILC) are lower than those without this step.
Dry etching of polysilicon with high selectivity using a chlorine-based plasma in an ECR reactor
(1996-07-01)
Chang, KM
;
Yeh, TH
;
Wang, SW
;
Li, CH
;
Yang, JY
Halogen-bearing gases have proved to be useful plasma discharge etchants for the fabrication of sub-micron poly-Si gate structures. In this paper, investigations of chlorine-based plasmas generated by an electron cyclotron resonance (ECR) reactor for poly-Si etching is studied. The influences of added oxygen, microwave power and RF power on etching characteristics are discussed. In addition, the etching mechanisms of the underlying oxide are developed. Finally, the Cl-2/HBr/O-2 mixed system is examined. The combined plasma exhibits the features of high selectivity, high anisotropy and high etching rate.
Dry etching of polysilicon with high selectivity using a chlorine-based plasma in an ECR reactor
(1996-07-01)
Chang, KM
;
Yeh, TH
;
Wang, SW
;
Li, CH
;
Yang, JY
Halogen-bearing gases have proved to be useful plasma discharge etchants for the fabrication of sub-micron poly-Si gate structures. In this paper, investigations of chlorine-based plasmas generated by an electron cyclotron resonance (ECR) reactor for poly-Si etching is studied. The influences of added oxygen, microwave power and RF power on etching characteristics are discussed. In addition, the etching mechanisms of the underlying oxide are developed. Finally, the Cl-2/HBr/O-2 mixed system is examined. The combined plasma exhibits the features of high selectivity, high anisotropy and high etching rate.
Effect of adding Ar on the thermal stability of chemical vapor deposited fluorinated silicon oxide using an indirect fluorinating precursor
(1997-05-12)
Chang, KM
;
Wang, SW
;
Li, CH
;
Yeh, TH
;
Yang, JY
For a low dielectric constant intermetal dielectric application, fluorinated silicon oxide (FxSiOy) films were deposited in an electron cyclotron resonance chemical vapor deposition system, with SiH4, O-2, and CF4 as the reaction gases. Since the CF4 is an indirect fluorinating precursor, the fluorinating mechanism resembles that of the oxide etching by a fluorocarbon plasma. Thermal stability of the incorporated fluorine (and hence, the dielectric constant) relies heavily on the deposition parameters and technologies. According to experimental results, adding Ar gas during deposition can improve the thermal stability of incorporated fluorine. Such an improvement is due to the fact that Ar sputtering enhances the removal of weakly bonded silicon fluoride on the as-deposited film surface, thereby elevating the mean bonding strength of fluoride remaining in the oxide. (C) 1997 American Institute of Physics.
Effects of cross-substrate interaction on biotrickling filtration for the control of VOC emissions
(2004-11-01)
Den, W
;
Huang, CP
;
Li, CH
;
環境工程研究所
;
生物科技學系
The effects of cross-substrate interaction to the performance of a gas-phase biotrickling filter for treating a mixture of volatile organic compounds (VOCs), including three structural heterologous in acetone, toluene, and trichloroethylene, were investigated. The biotrickling filter was inoculated with microbial consortium containing at least seven bacterial species utilizing either acetone or toluene, or both, as their carbon sources. In the performance study, the column operating under variable conditions typifying the waste gas emission from the microelectronics fabrication processes achieved a total hydrocarbon (THC) removal efficiency in excess of 85% and a mineralization capacity over 50% for THC mass loading as high as 36.2 g-CH4 m(-3) h(-1). The cross-substrate effects were examined by correlating the relative changes in the mass removal of each substrate with the biodegradative capability of the microbial consortium. The degradation of trichloroethylene was primarily due to co-metabolism by the toluene-oxidizing enzymes, but the results also indicated that trichloroethylene partially induced its own degradation. Concentration increases in acetone appeared to cause a diauxie effect that suppressed degradation of toluene and trichloroethylene, and shifted the microbial population toward the selective acetone-degraders. No irrecoverable toxicity or inhibitory effects were observed throughout the experiments. These results suggest that the relative VOC concentration in the waste gas mixture is a factor as important as the biodegradative function of the microbial consortium, and thus should be carefully evaluated to satisfy the treatment objectives. (C) 2004 Elsevier Ltd. All rights reserved.
Effects of gas ratio on electrical properties of electron-cyclotron-resonance nitride films grown at room temperature
(1996-06-01)
Chang, KM
;
Tsai, JY
;
Li, CH
;
Yeh, TH
;
Wang, SW
The effects on the electrical properties of electron-cyclotron-resonance (ECR) nitride films grown at room temperature with different SiH4/N-2 gas ratios from 7 sccm/43 seem to 2 sccm/48 seem are systematically investigated. Superior properties of the films with low bulk trap density 8X10(17) cm(-3), small trap cross section, high breakdown strength 12.12 MV/cm, and near-stoichiometric refractive index 2.0 are obtained when the gas ratio SiH4/N-2 is 5 sccm/45 sccm, the microwave power is 210 W, and the chamber pressure is 0.5 mTorr. With the microwave power, total gas flow rate, and total pressure unchanged, the decrease in SiH4/N-2 ratio lower than 5/45 results in larger trap density and some lower breakdown strength. On the other side, increasing SiH4/N-2 ratio results in higher hydrogen content, lower breakdown strength, and films which are easily degraded during consecutive voltage sweep. High microwave power will eliminate the weak bonds and strengthen the electrical stability of the high SiH4/N-2 ratio film. (C) 1996 American Institute of Physics.
Effects of gas ratio on electrical properties of electron-cyclotron-resonance nitride films grown at room temperature
(1996-06-01)
Chang, KM
;
Tsai, JY
;
Li, CH
;
Yeh, TH
;
Wang, SW
The effects on the electrical properties of electron-cyclotron-resonance (ECR) nitride films grown at room temperature with different SiH4/N-2 gas ratios from 7 sccm/43 seem to 2 sccm/48 seem are systematically investigated. Superior properties of the films with low bulk trap density 8X10(17) cm(-3), small trap cross section, high breakdown strength 12.12 MV/cm, and near-stoichiometric refractive index 2.0 are obtained when the gas ratio SiH4/N-2 is 5 sccm/45 sccm, the microwave power is 210 W, and the chamber pressure is 0.5 mTorr. With the microwave power, total gas flow rate, and total pressure unchanged, the decrease in SiH4/N-2 ratio lower than 5/45 results in larger trap density and some lower breakdown strength. On the other side, increasing SiH4/N-2 ratio results in higher hydrogen content, lower breakdown strength, and films which are easily degraded during consecutive voltage sweep. High microwave power will eliminate the weak bonds and strengthen the electrical stability of the high SiH4/N-2 ratio film. (C) 1996 American Institute of Physics.
Electrical transport phenomena in aromatic hydrocarbon polymer
(2003-02-01)
Liu, PT
;
Chang, TC
;
Yan, ST
;
Li, CH
;
Sze, SM
Electrical transport mechanisms in a low-permittivity aromatic hydrocarbon SiLK have been characterized using metal/SiLK/Si capacitors under both thermal and electric field stressing. Two distinct transport mechanisms dominate the leakage behavior of the polymer SiLK with Al and Cu electrodes, respectively. Al-electrode capacitors show Schottky-emission (SE)-type leakage behavior while Poole-Frenkel (PF) conduction resulted from trap generation in the SiLK polymer is responsible for the leakage of Cu-electrode capacitors. The trap barrier height has been extracted from the temperature dependence of leakage current. Copper penetration into the SiLK polymer leads to the generation of trap centers and seriously deteriorates dielectric characteristics. The transition of leakage conduction from SE to PF will exponentially lead to the insulating failure of the SiLK polymer. (C) 2003 The Electrochemical Society.
Fluorescence enhancement and structural development of sol-gel derived Er3+-doped SiO2 by yttrium codoping
(2002)
Chen, SY
;
Ting, CC
;
Li, CH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Er3+-Y3+ codoped SiO2 powdered bulks were prepared by a sol-gel process. The effect of Y3+ codoping on the fluorescence properties and structural development of Er3+-doped SiO2 is investigated. The maximum similar to1.54 mum photoluminescence (PL) intensity occurs in the sample with Er3+ (10 mol%)-Y3+ (50 mol%) codoped and annealed at 985 degreesC. This can be attributed to the competition between the content of hydroxy groups and Er site symmetry. Improvement of optimum PL properties due to Y3+ codoping by a factor of similar to20 for intensity and 1.8 for the full width at half maximum (57 nm) was obtained in comparison with the Er3+-doped SiO2 system. Extended X-ray absorption fine structure analysis shows that the local chemical environment of Er3+ ions in the Er3+-Y3+ codoped SiO2 is similar to that in Er2O3. The average spatial distance between Er3+ ions is enlarged due to a partial substitution of Y3+ for Er3+ ions in the Er2O3-like local structure, which results in a reduction of the concentration quenching effect.
Influences of damage and contamination from reactive ion etching on selective tungsten deposition in a low-pressure chemical-vapor-deposition reactor
(1996-09-01)
Chang, KM
;
Yeh, TH
;
Wang, SW
;
Li, CH
;
電子工程學系及電子研究所
Reactive ion etching (RIE) used in contact hole formation can result in damage and contamination of the underlying silicon substrate. In this work, influences of these phenomena on selective tungsten deposition in a low-pressure chemical-vapor-deposition reactor have been studied. The damage was generated because of ion bombardment and radiation-induced bonding changes in silicon lattices. It causes large Si consumption, rough W/Si interface during tungsten deposition, and large leakage current of W/Si Schottky structure. Simultaneously, contamination occurred with two forms of residual layers and impurity permeation layers in fluorocarbon-based RIE chemistries. The CF4/CHF3/O-2 RIE of oxide produces the SiFxCyOz complex layers deposited on the sidewall and on the Si surface as well as the embedding of impurities such as F and C in the Si substrate. The creep-up, selectivity loss, lateral encroachment, high W film resistivity, and rough W/Si interface have been observed in the contaminated samples. Accordingly, a post-RTE etching technique used to remove the damage and contaminants before tungsten growth has been developed. A CF4/O-2 plasma etching followed with an O-2 plasma ashing step exhibits the capability of efficient surface cleaning. The excellent characteristics of W films such as elimination of encroachment and creep-up, low selectivity loss (i.e., 0.25 pcs/cm(2)), low resistivity of W films, smooth W/Si interface, and very low leakage current of W/Si contacts are thus obtained. (C) 1996 American Institute of Physics.
Influences of deposition temperature on thermal stability and moisture resistance of chemical vapor deposited fluorinated silicon oxide by using indirect fluorinating precursor
(1996-08-26)
Chang, KM
;
Wang, SW
;
Wu, CJ
;
Yeh, TH
;
Li, CH
In this letter, fluorinated silicon oxide (FxSiOy) films were deposited in the electron cyclotron resonance (ECR) chemical vapor deposition system with SiH4, O-2, and CF4 as the reaction gases. The CF4, in contrast to SiF4 or FSi(OC2H5)(3) used in other reports, is an indirect fluorinating source. The fluorinating mechanism is similar to that of the etching of oxide by fluorocarbon plasma, therefore, the thermal stability of the incorporated fluorine must strongly depend on the deposition temperature. It is found that the thermal stability and moisture resistance are greatly improved by increasing the deposition temperature. However, the higher deposition temperature also results in a higher compressed stress and dielectric constant. Besides, to get the moisture resistance, the deposition temperature must be above 300 degrees C. On the other hand, ECR-SiO2 (without fluorination), even deposited at room temperature, is shown to have a good water resistance. Therefore, by choosing deposition temperature for FxSiOy to have enough thermal tolerance and capping with ECR-SiO2, the moisture resistor is suggested for the inter metal dielectric applications.
Influences of deposition temperature on thermal stability and moisture resistance of chemical vapor deposited fluorinated silicon oxide by using indirect fluorinating precursor
(1996-08-26)
Chang, KM
;
Wang, SW
;
Wu, CJ
;
Yeh, TH
;
Li, CH
In this letter, fluorinated silicon oxide (FxSiOy) films were deposited in the electron cyclotron resonance (ECR) chemical vapor deposition system with SiH4, O-2, and CF4 as the reaction gases. The CF4, in contrast to SiF4 or FSi(OC2H5)(3) used in other reports, is an indirect fluorinating source. The fluorinating mechanism is similar to that of the etching of oxide by fluorocarbon plasma, therefore, the thermal stability of the incorporated fluorine must strongly depend on the deposition temperature. It is found that the thermal stability and moisture resistance are greatly improved by increasing the deposition temperature. However, the higher deposition temperature also results in a higher compressed stress and dielectric constant. Besides, to get the moisture resistance, the deposition temperature must be above 300 degrees C. On the other hand, ECR-SiO2 (without fluorination), even deposited at room temperature, is shown to have a good water resistance. Therefore, by choosing deposition temperature for FxSiOy to have enough thermal tolerance and capping with ECR-SiO2, the moisture resistor is suggested for the inter metal dielectric applications.
Integration of finite element analysis and optimum design on gear systems
(2002-01-01)
Li, CH
;
Chiou, HS
;
Hung, CH
;
Chang, YY
;
Yen, CC
This work establishes a batch module called "integration of finite element analysis and optimum design" by taking gear systems as testing examples. This batch module consists of I-DEAS, ABAQUS/Standard and MOST software, which serve as the preprocessor, the numerical solver and the optimizer, respectively. A simple and practical method was developed, by which this module was enabled to search for contact nodes and elements and to automatically define the contact surfaces for contact analysis. A simple gear-pair system and a complete planetary gear system were successively used as testing examples for this integrated module. The module will automatically construct the geometrical model, analyze contact stress and solve for the optimal solutions when gearing parameters are input. The results are expected to enhance the technology of gear system design. (C) 2002 Elsevier Science B.V. All rights reserved.