Browsing by Author "Chen, SC"

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A physical model for the hysteresis phenomenon of the ultrathin ZrO2 film
(2002-10-01)
Wang, JC
;
Chiao, SH
;
Lee, CL
;
Lei, TF
;
Lin, YM
This work studies and presents an inner-interface trapping physical model for the ultra-thin (effective oxide thickness=15 Angstrom) zirconium oxide (ZrO2) film to explain its hysteresis phenomenon. The shift of the capacitance-voltage characteristics swept from accumulation to inversion and then swept back with light illumination is about 110 mV, which is larger than the shift without light illumination (similar to45 mV). The mobile ion effect is obviated using bias-temperature stress measurement. The proposed model successfully explains not only the phenomenon but also the thickness effect for the capacitance-voltage characteristics and the different turn-around voltages of the current density-voltage characteristics of the zirconium dielectrics. (C) 2002 American Institute of Physics.
A universal calibration curve for the TSI aerodynamic particle sizer
(2004-05-01)
Tsai, CJ
;
Chen, SC
;
Huang, CH
;
Chen, DR
;
環境工程研究所
A universal calibration curve for the accurate determination of particle aerodynamic diameter by the TSI APS (TSI, Inc., St. Paul, MN, USA) operating at various temperature, pressure, particle, and gas properties is proposed. The previous dimensionless APS response function proposed by Chen et al. (1985) uses the Stokes number as the governing parameter and is valid in the Stokesian regime only. In the non-Stokesian regime, an additional non-Stokesian correction factor is needed to correct for the indicated aerodynamic diameters of the APS. The universal curve in the present study is based on the relationship between V-p* and Stm, where V-p* = V-p /V-g and V-p is particle velocity, V-g is gas velocity at the nozzle exit, and Stm is modified Stokes number. Stm incorporates the non-Stokesian effect and is defined as 24St/(Re* C-D), where Re is the flow Reynolds number and C-D is the particle drag coefficient. We find that the new calibration curve can predict the particle aerodynamic diameter accurately within 6% of error under different operating conditions and particle/gas properties from the referenced condition without the need to introduce additional correction factors.
An interfacial investigation of high-dielectric constant material hafnium oxide on Si substrate
(2005-09-22)
Chen, SC
;
Lou, JC
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Chien, CH
;
Liu, PT
;
Chang, TC
In this study, the hump in the capacitance-voltage (C-V) curves, variation of leakage current, interfacial layer increase, and electron trapping in non-surface treated hafnium oxide (HfO2) samples were observed and investigated. From the results of the investigation, it was found that both rapid thermal oxidation and NH3 surface treatments improved the C-V curves. In addition, it was observed that samples treated with ammonia exhibited a lower leakage current when compared with the others. From the results of the dielectric, leakage current study, a severe electron trapping effect was exhibited under higher electric field stress. Finally, the conduction mechanism in the HfO2 thin film was dominated by Frenkel-Poole emission in a high electric field. (c) 2005 Elsevier B.V All rights reserved.
Annealing effect on boron high-energy-ion-implantation-induced defects in
(2004-08-01)
Hsu, WC
;
Liang, MS
;
Chen, SC
;
Chen, MC
;
電子工程學系及電子研究所
In this work, we investigate the annealing effect on defects in Si induced by boron high-energy (1.5 MeV) ion implantation with respect to implantation dose (1.1 X 10(13) and 5 x 10(13) cm(-2)) as well as annealing scheme [rapid thermal annealing (RTA) and furnace annealing (FA)]. The higher dose implantation resulted in more serious degradation of the minority carrier generation lifetime in the implanted layers. Also, the degree of lifetime recovery by either RTA or FA was very limited with the higher dose implantation, presumably due to the presence of the implantation-induced dislocations. The degradation of the lifetime in the lower dose-implanted sample could be significantly recovered by the annealing process, particularly the RTA scheme; this is presumably because RTA has a better ability to reduce the implantation-induced interstitials.
Anomalous substrate current in polycrystalline silicon thin-film transistors
(2003)
Zan, HW
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Chen, SC
;
Wang, SH
;
Chang, CY
;
電子工程學系及電子研究所
In this paper, the substrate current of polycrystalline silicon thin-film transistors was measured and investigated the first time. With typical T-gate pattered structure, an abnormal high substrate current was found while devices were operated under high gate voltage. This is generated from the parasitic tunnelling current between the n+ inversion region and the p+ body region. Under lower gate voltage, substrate current generated from impact ionization effect is also observed and characterized. After extracting fitting parameters from the device characteristics, a simple physically-based model was established and compared with the measured results. A plausible grain boundary scattering effect was included in the proposed model. Good agreements were found through a wide range of gate bias and various drain bias, verifying the validity of this unified model.
Connecting wave functions at a three-leg junction of one-dimensional channels
(2006-01-01)
Voo, KK
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Chen, SC
;
Tang, CS
;
Chu, CS
;
電子物理學系
We propose a scheme to connect the wave functions on different one-dimensional branches of a three-leg junction (Y junction). Our scheme differs from that due to Griffith [Trans. Faraday Soc. 49, 345 (1953)] in the respect that ours can model the difference in the widths of the quasi-one-dimensional channels in different systems. We test our scheme by comparing results from a doubly connected one-dimensional system and a related quasi-one-dimensional system, and we find a good agreement. Therefore our scheme may be useful in the construction of one-dimensional effective models out of (multiply connected) quasi-one-dimensional systems.
Effect of catalyst on growth behavior of carbon nanotube synthesizing by microwave heating thermal chemical vapor deposition process
(2001-05-01)
Chen, SC
;
Shih, LY
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Chang, YC
;
Tu, GC
;
Lin, IN
A modified chemical vapor deposition process, which utilizes a susceptor to absorb the microwave and to self generate the heat, for heating up the Si substrate, was used for growing carbon nanotubes (CNTs). The advantage of such a process is that the deposition chamber can be maintained at around room temperature with only the substrates localized heated, such that the deposition temperature can be more precisely controlled. The influence of the pretreatment process for catalyst-coated Si substrates on growth behavior of CNTs and the related electron field emission properties were systematically examined. Among the form of catalyst used, the Fe(NO3)(3)-ethythersilicate mixture performs much better than the de sputtered Fe films. The higher the concentration of Fe species in the catalyst mixture, the denser the CNTs formed on the subs;rates, resulting in better held emission properties. Thus grown CNTs can be turned on at a very low field (E(0)congruent to0.78 V/mum), achieving a very large emission current density (J(e)congruent to 13 mA/cm(2)) at 5.5 V/mum applied field. (C) 2001 American Vacuum Society.
Effects of base oxide in HfSiO/SiO2 high-k gate stacks
(2004)
Wu, WH
;
Chen, MC
;
Wang, MF
;
Hou, TH
;
Yao, LG
Electrical characteristics of HfSiO/SiO2 high-k gate stacks have been extensively explored with regard to the effects of base oxide. The flatband voltage shift in N/PMOS capacitors is independent of base oxide thickness, and the dielectric breakdown of the gate stacks is determined by base oxide. In addition, base oxide thickness has a great impact on device performance and charge trapping, presumably due to remote Coulomb scattering (RCS) in the HfSiO bulk layer and direct tunneling through the base oxide. Threshold voltage instability induced by charge trapping will be a major reliability concern for Hf-based high-k gate dielectrics in the future.
Effects of base oxide thickness and silicon composition on charge trapping in HfSiO/SiO(2) high-k gate stacks
(2005-08-01)
Wu, WH
;
Chen, MC
;
Tsui, BY
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How, YT
;
Yao, LG
This work investigates the fundamentals of charge trapping and the effects of base oxide thickness and Si composition on charge trapping in HfSiO/SiO(2) high-k gate stacks using positive-bias temperature (PBT) stressing scheme. During the PBT stress, threshold voltage shift and saturation drain current degradation induced by charge trapping continue to grow and eventually become saturated, whereas the subthreshold swing and maximum transconductance remain unchanged. The extent of charge trapping increases with the decrease of base oxide thickness and Si composition in the HfSiO film, which can be explained by considering the channel-to-bulk tunneling time constant and the amount of neutral Hf-OH trapping centers in the HfSiO bulk layer. The power law dependence of saturation drain current degradation on the gate bias voltage indicates that charge trapping would become more significant if thin base oxide and low Si composition were employed in the further scaled HfSiO/SiO(2) high-k gate stacks.
Effects of base oxide thickness and silicon composition on charge trapping in HfSiO/SiO2 high-k gate stacks
(2005-08-01)
Wu, WH
;
Chen, MC
;
Tsui, BY
;
How, YT
;
Yao, LG
This work investigates the fundamentals of charge trapping and the effects of base oxide thickness and Si composition on charge trapping in HfSiO/SiO2 high-k gate stacks using positive-bias temperature (PBT) stressing scheme. During the PBT stress, threshold voltage shift and saturation drain current degradation induced by charge trapping continue to grow and eventually become saturated, whereas the subthreshold swing and maximum transconductance remain unchanged. The extent of charge trapping increases with the decrease of base oxide thickness and Si composition in the HfSiO film, which can be explained by considering the channel-to-bulk tunneling time constant and the amount of neutral Hf-OH trapping centers in the HfSiO bulk layer. The power law dependence of saturation drain current degradation on the gate bias voltage indicates that charge trapping would become more significant if thin base oxide and low Si composition were employed in the further scaled HfSiO/SiO2 high-k gate stacks.
Electroluminescence characteristics of aromatic polyimides by vapor deposition polymerization
(2003)
Hsu, SC
;
Whang, WT
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Chen, SC
;
材料科學與工程學系
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Department of Materials Science and Engineering
Light emitting polyimide (PI) thin films are successfully prepared from two kinds of diamines: 2,5-Bis(4-aminophenyl)-1,3,4-oxadiazole (BAO) and 4,4'-(9-Fluorenylidene)dianiline (BAPF) reacting with 4,4'-(Hexafluoroisopropylidene)diphthalic anhydride (6FDA) by vapor deposition polymerization (VDP). We succeed to reduce the thickness of the thin polyimide film to 150 Angstrom, and the threshold voltage of BAO-6FDA and BAPF-6FDA PI light-emitting diodes to 4.5 V and 6.5 V respectively. The root mean square of the surface roughness of the BAO-6FDA and BAPF-6FDA PI films are 8.8 Angstrom and 4.7 Angstrom respectively. But that of the BAO-6FDA film from wet coating process is 37.1 Angstrom. Apparently, VDP process is the better way to produce smooth polyimide film. The BAO-6FDA LED film emits a broader electroluminscence (EL) band, covering the full range of visible light (400 nm to 700 nm), than the BAPF-6FDA LED. However, the electroluminescence efficiency of BAPF-6FDA LED device is better than BAO-6FDA LED device. It is due to the better balance on the hole and electron injection in the former and better intermolecular charge transfer.
Evaluation of a modified chitosan biopolymer for coagulation of colloidal particles
(1999-02-15)
Pan, JRS
;
Huang, CP
;
Chen, SC
;
Chung, YC
;
環境工程研究所
Chitosan, a deacetylated derivative of chitin, is a biodegradable cationic polymer. Chitosan can be a potential substitute for aluminum salts and synthetic polyelectrolytes in water treatment because it can: (1) avoid the health effects from residual aluminum (III) and synthetic polymers; (2) produce biodegradable sludge; and (3) reuse the crab shell. Chitosan can be modified with various pretreatments including dissolution in acid solution and various deacetylation conditions to improve its coagulation efficiency. In this study, coagulations of synthetic and real water with the modified chitosan, mixed coagulant of chitosan and PACl at various ratios, and PACl were compared. The efficiency was evaluated by the factors of settling rate, hoc diameter, and residual turbidity. Coagulation with chitosan alone required least dosage. Chitosan coagulants also produced larger flee with higher settling velocity. Satisfactory results were obtained from the mixed coagulant of chitosan/PACl = 4:1. Although low pH decreased the optimal dosage, the flocs produced were smaller with slower settling rate. Increasing the rapid mixing strength improved the coagulation only when the applied dosage was less than the optimum dosage. Studies using other particles such as kaolinite and clay indicate that the properties of particles have a significant effect on the chitosan coagulation efficiency. (C) 1999 Elsevier Science B.V. All rights reserved.
HfAlON n-MOSFETs incorporating low-work function gate using ytterbium silicide
(2006-06-01)
Wu, CH
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Hung, BF
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Chin, A
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Wang, SJ
;
Yen, FY
The authors have fabricated low-temperature fully silicided YbSi2-x-gated n-MOSFETs that used an HfAION gate dielectric with a 1.7-nm EOT. After a 600 degrees C rapid thermal annealing, these devices displayed an effective work function of 4.1 eV and a peak electron mobility of 180 cm(2)/V(.)s. They have additional merit of a process compatible with current very large scale integration fabrication lines.
Impact of STI on the reliability of narrow-width pMOSFETs with advanced ALD N/O gate stack
(2006-03-01)
Chung, SS
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Yeh, CH
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Feng, HJ
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Lai, CS
;
Yang, JJ
For the first time, a shallow trench isolation (STI)-induced enhanced degradation in pMOSFETs for ultrathin gate oxide devices has been observed. The ID degradation is enhanced as a reduction in the gate width and the hot carrier (HC) or negative bias temperature instability (NBTI) effect. Extensive studies have been compared for atomic layer deposition (ALD)-grown and plasma-treated oxide pMOSFETs. Different temperature dependences were observed. At room temperature, hole trap is dominant for the device degradation, in which holetrap-induced V-T is significant, whereas at high temperature under NBTI stress, interface trap becomes more significant, which dominates the device ID degradation. In addition, the V-T rolloff can be modeled as a width narrowing effect specifically for STI. More importantly, the NBTI-induced interface/oxide traps are strongly related to the hydrogen and N-2 content in the gate oxide formation process. The interface trap generation is suppressed efficiently using the ALD-grown gate oxide. These results provide a valuable guideline for the understanding of the HC and NBTI reliabilities in an advanced ALD-grown gate oxide processes/devices.
Impacts of HF etching on ultra-thin core gate oxide integrity in dual gate oxide CMOS technology
(2003)
Lee, DY
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Lin, HC
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Chen, CL
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Huang, TY
;
Wang, TH
In this paper, we investigate the effects of HF etching on the integrity of ultra-thin oxides in dual gate oxide (DGO) CMOS technologies. We found that both the BF concentration in the etching solution and the over etching (OE) time are important parameters that greatly affect the device performance and reliability. Our results indicate that, with a proper over etching period, using a heavy BF solution results in better ultra-thin gate oxides in terms of reduced defect density, improved device performance and reliability, compared to using diluted BF solution. It is also found for the first time that negative-bias-temperature instability (NBTI) immunity for PMOSFETs is improved by using heavy HF solution.
InAs/GaAs quantum dot infrared photodetectors with different growth temperatures
(2003-10-01)
Wang, SY
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Chen, SC
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Lin, SD
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Lin, CJ
;
Lee, CP
InAs/GaAs quantum dot infrared photodetectors were fabricated with quantum dots grown at three different temperatures. Large detection wavelength shift (5-14.5 mum) was demonstrated by changing 40 degrees of the epitaxy temperature. The smaller quantum dots grown at lower temperature generate 14.5 mum responses. The detectivity of the normal incident 15 mum QDIP at 77 K is 3 x 10(8) cm Hz(1/2)/W. A three-color detector was also demonstrated with quantum dots grown at medium temperature. The three-color detection comes from two groups of different sizes of dots within one QD layer. This new type of multicolor detector shows unique temperature tuning behavior that was never reported before. (C) 2003 Elsevier B.V. All rights reserved.
Magnetic analysis of a micromachined magnetic actuator using the finite element method
(1999)
Ko, CH
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Yang, JJ
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Chiou, JC
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Chen, SC
;
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 condition for modification of chitosan: A biopolymer for coagulation of colloidal particles
(2000-02-01)
Huang, CP
;
Chen, SC
;
Pan, JR
;
環境工程研究所
;
Institute of Environmental Engineering
Chitosan, an acetylated derivative of chitin, is a biodegradable cationic polymer. Chitosan can be a promising substitute for alum in the coagulation process, because of its potential feasibility in coagulation without posing any health threat as the residual aluminium and other synthetic polymers do. In this study, various pretreatment conditions were tested in search of the optimum chitosan modification. Batch tests with synthetic source water suggest that the optimal pretreatment condition to prepare modified chitosan coagulant is deacetylation by 45% alkali solution for 60 min, followed by dissolution in 0.1% hydrochloric acid. (C) 2000 Elsevier Science Ltd. All rights reserved.
Preparation and characterization of garnet phosphor nanoparticles derived from oxalate coprecipitation
(1999-05-01)
Chen, TM
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Chen, SC
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Yu, CJ
;
應用化學系
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Department of Applied Chemistry
Terbium-activated Y3Al5O12 (YAG:Tb) phosphor nanoparticles with homogeneous grain size and crystallinity have been prepared at 1000 degrees C by heat treatment of a metal oxalate precursor derived from an alkaline coprecipitation route, The diffraction profile of as-prepared YAG:Tb nanoparticles can be indexed as a garnet structure and exhibits peak broadening phenonmenon, as revealed by X-ray diffraction (XRD) data. Grains of YAG:Tb nanoparticles appear to be irregularly spherical or elliptical and their sizes range from 60 to 70 nm, as indicated by morphological studies from bright-field transmission electron microscopy (TEM) imaging. Furthermore, the photoluminescence (PL) spectra of the (Y2.9Tb0.1)Al5O12 phase were investigated to determine the energy level of electron transition related to luminescence processes and the possible blue shift in the excitation or emission PL spectra, (C) 1999 Academic Press.
Process quality analysis of products
(2002)
Chen, KS
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Chen, SC
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Li, RK
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工業工程與管理學系
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Department of Industrial Engineering and Management
Process capability indices are widely regarded as a flexible means of evaluating the quality and performance of a process. Accreditation by the Quality System Requirement QS9000 requires an agent to conduct a global evaluation on the process capability over the entire product family from a plant. Generally, the process capability of the whole product family is an important reference for evaluation when producing a new product or designing a new process. Therefore developing a scheme to evaluate the process capability of the whole product family or series is crucial for industry This paper takes the production of capacitors as an example of a new method for evaluating the process capability of a whole product family. As the quality characteristic for producing capacitors is "the smaller the better", the upper specification limits of the capacitors of various specifications should first be established. The process capability index C-pu for products for which "smaller is better" is then used as an evaluation toot to calculate the process capability indices for individual specified products. The relationship between the process capability indices and the yield will be studied. A process capability index is proposed to reflect the global yield of the whole product family and to serve as a reference for evaluating process capability for designing new processes or developing new products. The process capabilities for all products can thus be evaluated and the performance of each process can be evaluated according to the colour management method. Managers can determine easily whether products meet their specifications and take action to improve them if necessary, according to the colour management method.