Browsing by Author "Wang, TC"

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A discussion on the Josephson AC effect and the fractional energy quantization
(1996-04-01)
Wang, TC
;
Gou, YS
;
交大名義發表
;
電子物理學系
;
National Chiao Tung University
The Josephson ac effect is assumed to be a ''phase locking'' behavior of the damped periodically driven oscillations. By reviewing a discrete time treatment of such a nonlinear dynamical behavior, this letter discusses a macroscopic fractional energy quantization interpretation for the Josephson ac effect.
A modified multi-chemical spray cleaning process for post shallow trench isolation chemical mechanical polishing cleaning application
(1998-11-02)
Wang, YL
;
Wang, TC
;
Wu, J
;
Tseng, WT
;
Lin, CF
Chemical mechanical planarization (CMP) has become widely accepted for the formation of device interconnect structures. Shallow trench isolation technology (STI) utilizes CMP and has been applied to deep-sub-micron processes. Poly Si, CVD Si or SiO2 can be grown or deposited in the trench and planarized by a CMP process. However, the typical wafer surface is contaminated with slurry particles and metallic impurities after the CMP process. The silica particles may damage the VLSI patterns and the metallic impurities can induce many crystal defects in Si wafers during the following furnace processing. Therefore, the post CMP clean is a very important step for the STI process. However, the wafer for poly-Si surface is hydrophobic, SiO2 surface is hydrophilic and Si film is very easy to charge up. Thus, the defect can be difficult to remove by a conventional cleaning technique. In this study: we propose the use of a modified multi-chemicals spray cleaning process for post STI CMP cleaning. We used a modified and heated ammonia/peroxide mix (APM) clean with an ammonia pre-soak and an HF step to etch a thin layer for the removal of trapped metallic ions which can be followed by a hydrochloric/peroxide mix (HPM) clean process to assist in the removal of metallic ions. (C) 1998 Elsevier Science S.A. All rights reserved.
Activated kinetics of room-temperature-deposited SrTiO(3) thin films investigated by reflection-high-energy-electron-diffraction-monitored annealing at different heating rates
(2005-02-01)
Wang, TC
;
Lee, JY
;
Hsieh, CC
;
Juang, JY
;
Wu, KH
A series of reflection-high-energy-electron-diffraction-monitored annealings with different heating rates have been conducted on Strontium Titanate films deposited by laser ablation at room temperature. All the films exhibited a steep RHEED intensity rise above 660 degrees C during annealing with increasing temperature. The peak temperatures of the intensity derivatives were found to shift at different heating rates, suggesting an activated surface state transition. A Kissinger type plot of the peak temperatures showed an effective activation energy of 4 eV.
Activated kinetics of room-temperature-deposited SrTiO3 thin films investigated by reflection-high-energy-electron-diffraction-monitored annealing at different heating rates
(2005-02-01)
Wang, TC
;
Lee, JY
;
Hsieh, CC
;
Juang, JY
;
Wu, KH
A series of reflection-high-energy-electron-diffraction-monitored annealings with different heating rates have been conducted on Strontium Titanate films deposited by laser ablation at room temperature. All the films exhibited a steep RHEED intensity rise above 660 degrees C during annealing with increasing temperature. The peak temperatures of the intensity derivatives were found to shift at different heating rates, suggesting an activated surface state transition. A Kissinger type plot of the peak temperatures showed an effective activation energy of 4 eV.
Comparison of characteristics and integration of copper diffusion-barrier dielectrics
(2006-03-01)
Wang, TC
;
Cheng, YL
;
Wang, YL
;
Hsieh, TE
;
Hwang, GJ
The characteristics of various copper (Cu) barrier layers, including SiN, SiCN, and SiCO, were investigated in this work. Carbon-based barrier films (SiCN and SiCO) improved the dielectric constant and line-to-line capacitance, but led to sacrifice in film deposition rate, diffusion-barrier performance, and adhesion strength to Cu in comparison with SiN films. In addition, SiN and SiCO films showed the superior electromigration (EM) performance and stress-induced void migration (SM) performance, respectively. Furthermore, the reliability results of SM and EM are strongly related to the barrier film stress characteristics and the adhesion strength between Cu layers. Therefore, optimization of the barrier layer stress and the enhancement of the interfacial condition between Cu and barrier films are crucial to significantly improve reliability. (c) 2005 Elsevier B.V. All rights reserved.
Copper surface protection with a completely enclosed copper structure for a damascene process
(2004-01-30)
Wang, TC
;
Hsieh, TE
;
Wang, YL
;
Wu, YL
;
Lo, KY
As integrated circuit manufacture moving to copper interconnection for the most advanced products, protection of copper (Cu) surfaces becomes a major challenge for the back-end-of-line manufacturing process. The damages on Cu, such as Cu corrosion and oxidation, are often observed on wafers when exposing bare Cu surface in the presence of moisture and/or acidic gases. Furthermore, the Cu oxide results in poor adhesion both at Cu/barrier layer and Cu/stop layer interfaces. In this work, a novel Cu dual damascene structure which completely encloses the Cu surface with a tantalum nitride layer is presented. This capping layer avoids the Cu corrosion and oxidation due to its ability to keep moisture and acid off and away from the Cu surface. (C) 2003 Elsevier Science B.V. All rights reserved.
Effect of strength and fiber reinforcement on fire resistance of high-strength concrete columns
(2003-02-01)
Kodur, VKR
;
Cheng, FP
;
Wang, TC
;
Sultan, MA
;
土木工程學系
In this paper, results from fire resistance experiments on five types of reinforced concrete columns are presented. The variables considered in the study include concrete strength [normal-strength concrete (NSC) and high-strength concrete (HSC)], aggregate type (siliceous and carbonate aggregate), and fiber reinforcement (steel and polypropylene fibers). Data from the study is used to determine the structural behavior of HSC columns at elevated temperatures. A comparison is made of the fire resistance performance of HSC columns with that of NSC and fiber-reinforced HSC columns. The factors that influence the thermal and structural behavior of HSC concrete columns under fire conditions are discussed. The results show that the fire resistance of a NSC column is higher than that of a HSC column. Also, the addition of polypropylene fibers and the use of carbonate aggregate improve fire resistance.
Growth kinetics of homoepitaxial strontium titanate films by interrupted pulsed laser deposition
(2001-08-01)
Lee, JY
;
Wang, TC
;
Chen, SF
;
Juang, JY
;
Lin, JY
The effects of the initial surface state on the evolution kinetics of the surface morphology of strontium titanate (STO) films was investigated by in-situ monitoring the intensity variations of reflection high-energy electron diffraction (RHEED). In order to create various surface states prior to subsequent depositions, we intentionally interrupted the pulsed laser deposition (PLD) at various points during the whole deposition course to perform in-situ annealing over various periods of time. The depth of the initial drop of RHEED intensity, which is a direct indication of changes in surface step densities, shows two distinct time scales. The results suggest that the evolution of a growing surface, and hence the ultimate film surface morphology, may be manipulated by controlling the number density of the as-deposited growing islands through interrupted annealing.
Improvement of near-ultraviolet InGaN/GaN light-emitting diodes by inserting an in situ rough SiN(x) interlayer in n-GaN layers
(2003-10-27)
Tu, RC
;
Chuo, CC
;
Pan, SM
;
Fan, YM
;
Tsai, CE
Near-ultraviolet 400-nm InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with and without an in situ rough SiN(x) interlayer inserted into the n-GaN underlying layer were grown on c-face sapphire substrates by metalorganic vapor phase epitaxy. Inserting the SiN(x) interlayer into the n-GaN underlying layer slightly reduced leakage current induced by reducing the defect density. Additionally, an enhancement of light extraction for the LED with a SiN(x) interlayer is expected because of the increased intensity of light scattered on the SiN(x) nanomask, changing the directions of propagation of light. Consequently, the emission efficiency of an LED with an in situ rough SiN(x) interlayer doubles that without a SiN(x) interlayer. (C) 2003 American Institute of Physics.
Improvement of near-ultraviolet InGaN/GaN light-emitting diodes by inserting an in situ rough SiNx interlayer in n-GaN layers
(2003-10-27)
Tu, RC
;
Chuo, CC
;
Pan, SM
;
Fan, YM
;
Tsai, CE
Near-ultraviolet 400-nm InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with and without an in situ rough SiNx interlayer inserted into the n-GaN underlying layer were grown on c-face sapphire substrates by metalorganic vapor phase epitaxy. Inserting the SiNx interlayer into the n-GaN underlying layer slightly reduced leakage current induced by reducing the defect density. Additionally, an enhancement of light extraction for the LED with a SiNx interlayer is expected because of the increased intensity of light scattered on the SiNx nanomask, changing the directions of propagation of light. Consequently, the emission efficiency of an LED with an in situ rough SiNx interlayer doubles that without a SiNx interlayer. (C) 2003 American Institute of Physics.
Investigations of effects of bias polarization and chemical parameters on morphology and filling capability of 130 nm damascene electroplated copper
(2001-05-01)
Chang, SC
;
Shieh, JM
;
Lin, KC
;
Dai, BT
;
Wang, TC
Through elucidating the effects of current density, cupric ion concentration, bath temperature, and air agitation on plating uniformity and filling capability of copper electroplating, the deposition of copper in an acid copper electrolyte will be illustrated to scale down to the sub-0.13 mum features with uniform plating, which is required by chemical mechanical polishing in current damascene techniques. In order to achieve the defect-free filling in sub-0.13 mum vias and trenches, the electrolyte must be composed of proper amounts of cupric ions, sulfuric acid, chloride ions, wetting agent, and filling promoter. The supplied current controlled at a lower current density, agitation acceded to the electroplating process were found as further keys. In the electrolyte, the filling promoter was consisted essentially of thiazole derivatives with benzyl groups and amino-group (-NH2) offering sufficient inhibition on copper depositing and selective inhibition gradient. Moreover, a lower resistivity film and higher filling capability could be obtained by using periodic pulse current plating as compared with direct current plating. (C) 2001 American Vacuum Society.
Novel strategies of FSG-CMP for within-wafer uniformity improvement and wafer edge yield enhancement beyond 0.18 micro technologies
(2001)
Chen, KW
;
Wang, YL
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Chang, L
;
Liu, CW
;
Lin, YK
The low-K films and higher multiple stacked layers would be widely applied for ultra large-scale integrated circuits [1][2]. However for 8" (200mm) or 12" (300mm) wafer the phenomena of wafer edge collapsing in higher interlayer low-K dielectric film causes from CMP polishing effect. (Shown in Fig. 1). Conventionally a amount of work has been developed in the optimization of different parameters, such as low pressure and high speed [3], metal dummy filling [4], harder pad used [4], and design of polishing head in order to resolve the problems. But these methods only engaged in design of experiment, not addressed in CMP theory of edge collapsing and controlling way. In this paper we will discuss the theory applied in Preston equation to explain the polishing behavior in wafer edge. In advance, to implement the theory, we adopted novel strategies, including of different polishing head (sweep) vibration and pad edge sprayer methods, even new wafer retaining ring design and novel delivery slurry methods in advance. The characteristics of within wafer nonuniformity and edge profile against CMP polishing low-k films, fluorinated silicate glass (FSG), would be evaluated in this new strategy action. Besides, the dimension of metal line and VIA, and edge die-yield can be directly responded to the edge profile improvement. From the action results, the average 7 similar to 10% yield improvement of 0.18 technology can be achieved, especially 15% edge-die yield improvement. The edge profile could promote the phenomena of no collapsing from the original 75 mm to 95 mm of wafer center-to-edge distance, excluding 3 mm edge of 8-inch wafer. These high efficient strategies for within-wafer planarization and edge profile is also proven and fulfilled with the reducing over 50% VIA CD deviation on the rule of lithography.
Predicting the fire resistance behaviour of high strength concrete columns
(2004-02-01)
Kodur, VKR
;
Wang, TC
;
Cheng, FP
;
土木工程學系
;
Department of Civil Engineering
A numerical model, in the form of a computer program, for tracing the behaviour of high performance concrete (HPC) columns exposed to fire is presented. The three stages, associated with the thermal and structural analysis, for the calculation of fire resistance of columns are explained. A simplified approach is proposed to account for spalling under fire conditions. The use of the computer program for tracing the response of an HPC column from the initial pre-loading stage to collapse, due to fire, is demonstrated. The validity of the numerical model used in the program is established by comparing the predictions from the computer program with results from full-scale fire resistance tests. Details of fire resistance experiments carried out on HPC columns, together with results, are presented. The computer program can be used to predict the fire resistance of HPC columns for any value of the significant parameters, such as load, section dimensions, fiber reinforcement, column length, concrete strength, aggregate type, and fiber reinforcement. (C) 2003 Elsevier Ltd. All rights reserved.
Quaternary AlInGaN multiple quantum well 368 nm light-emitting diode
(2006-01-25)
Wang, TC
;
Kuo, HC
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Lee, ZH
;
Chuo, CC
;
Tsai, MY
We report high output power from AlInGaN multiple quantum well (MQW) ultraviolet light-emitting diodes. The high Al containing cladding layer, electron blocking layer and p-contact layer were chosen for transparency at 365 nm to reduce the internal absorption, reduce electron overflow and enhance output power. The UV output power was as high as 1.52 mW at 20 mA at 368 nm under room temperature CW operation. The maximum output power in CW operation is 11 mW at 170 mA. In this letter, we demonstrate a helpful and easy way to measure and calculate the junction temperature of AlInGaN UVLEDs. (c) 2005 Elsevier B.V. All rights reserved.
RHEED in-situ monitored step edge diffusion during interrupted laser ablation epitaxy growth of SrTiO3
(2004-12-01)
Wang, TC
;
Lee, JY
;
Hsieh, CC
;
Juang, JY
;
Wu, KH
A series of investigations on the interrupted deposition of laser ablation strontium titanate epitaxy growth were conducted. RHEED intensity recovery curves at various temperatures show a near-quadratic power law dependence on annealing time. Combined with the evidence showing the intimate correlation between the step edge density and the RHEED intensity, a diffusion Arrhenius plot with the activation energy of 1.0 eV was obtained for the kinetics of step edge migration.
ROBIN: a tool for genome rearrangement of block-interchanges
(2005-06-01)
Lu, CL
;
Wang, TC
;
Lin, YC
;
Tang, CY
;
生物科技學系
ROBIN is a web server for analyzing genome rearrangement of block-interchanges between two chromosomal genomes. It takes two or more linear/circular chromosomes as its input, and computes the number of minimum block-interchange rearrangements between any two input chromosomes for transforming one chromosome into another and also determines an optimal scenario taking this number of rearrangements. The input can be either bacterial-size sequence data or landmark-order data. If the input is sequence data, ROBIN will automatically search for the identical landmarks that are the homologous/conserved regions shared by all the input sequences.
Stress migration and electromigration improvement for copper dual damascene interconnection
(2005)
Wang, TC
;
Hsieh, TE
;
Wang, MT
;
Su, DS
;
Chang, CH
Stress migration (SM) and electromigration (EM) were widely used to study the performance of interconnection process of metal/via formation in copper dual damascene of wafers. Necking and voids at the via bottom were important in causing failures in tests of stress migration and electromigration. In this report, the contamination of the bottom of via, which results in poor step coverage, the adhesion of seed layers, and poor copper grain formation are identified to be the underlying causes of the necking and void formation after the first EM and SM tests are performed. The contamination of the via formation processes included via etching, trench etching, and barrier/seed layer depositions. A well-shaped via profile can be optimized using three methods, the first involves Cu/SiN interface stress, the second involves Cu grain growth, and the third involves post via etching clean study. Eliminating the contamination of the via bottom and optimizing step coverage and adhesion of the barrier seed layers improve the EM and SM performance from time-to-fail = 13 to 59 s, in the copper-related processes for fabricating 300 mm wafers using technology that is beyond 0.13 mm technology. (C) 2004 The Electrochemical Society.
Stress-strain curves for high strength concrete at elevated temperatures
(2004-01-01)
Cheng, FP
;
Kodur, VKR
;
Wang, TC
;
土木工程學系
;
Department of Civil Engineering
The effects of high temperature on the strength and stress-strain relationship of high strength concrete (HSC) were investigated. Stress-strain curve tests were conducted at various temperatures (20, 100, 200, 400, 600, and 800degreesC) for four types of HSC. The variables considered in the experimental study included concrete strength, type of aggregate, and the addition of steel fibers. Results from stress-strain curve tests show that plain HSC exhibits brittle properties below 600degreesC, and ductility above 600degreesC. HSC with steel fibers exhibits ductility for temperatures over 400degreesC. The compressive strength of HSC decreases by about a quarter of its room temperature strength within the range of 100-400degreesC. The strength further decreases with the increase of temperature and reaches about a quarter of its initial strength at 800degreesC. The strain at peak loading increases with temperature, from 0.003 at room temperature to 0.02 at 800degreesC. Further, the increase in strains for carbonate aggregate HSC is larger than that for siliceous aggregate HSC.
Study of InGaN multiple quantum dots by metal organic chemical vapor deposition
(2006-04-01)
Wang, TC
;
Kuo, HC
;
Lu, TC
;
Tsai, CE
;
Tsai, MY
We reports a study of InGaN Multiple quantum dot layers. Using the in-situ SiNx treatment process, InGaN multiple quantum dot layers were successfully developed. The InGaN multiple quantum dot layers were constructed with SiNx dot mask layers, InGaN dot layers, and GaN cap layers on a 2-mu m-thick GaN underlying layer on a sapphire substrate. Optical properties including room temperature photoluminescence (PL), temperature dependent PL, and low power power-dependent PL were examined and discussed. The structure was also analyzed by transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) line scan.
Thermally activated diffusion observed by in situ reflection high energy electron diffraction intensity monitoring on interrupted SrTiO3 homoepitaxial growth
(2004-02-01)
Wang, TC
;
Juang, JY
;
Wu, KH
;
Uen, TM
;
Gou, YS
The reflection high energy electron diffraction (RHEED) intensity is reported following a quadratic power law dependence on annealing time for interrupted laser ablation-grown strontium titanate films. The activation energy of 1.0eV can further be obtained from the diffusion Arrhenius plot by assuming a direct proportionality between the RHEED intensity and the diffusion length.