Browsing by Author "Chen, JS"

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A CMOS bandgap reference circuit for sub-1-V operation without using extra low-threshold-voltage device
(2005-11-01)
Kew, MD
;
Chen, JS
;
Chu, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A new sub-1-V CMOS bandgap voltage reference without using low-threshold-voltage device is presented in this paper. The new proposed sub-1-V bandgap reference with startup circuit has been successfully verified in a standard 0.25-mu n CMOS process, where the occupied silicon area is only 177 pm x 106 pm. The experimental results have shown that, with the minimum supply voltage of 0.85 V, the output reference voltage is 238.2 mV at room temperature, and the temperature coefficient is 58.1 ppm/degrees C from - 10 degrees C to 120 degrees C without laser trimming. Under the supply voltage of 0.85 V, the average power supply rejection ratio (PSRR) is -33.2dB at 10 kHz.
A consistent determination of the dimerization constants of the self-association of 2,2-dimethyl-3-ethyl-3-pentanol in carbon tetrachloride from its infrared spectral data
(2005-12-01)
Kao, DY
;
Shu, WT
;
Chen, JS
;
應用化學系
;
Department of Applied Chemistry
Two equations of linear type (Eqs. 10 and 17 in the text) have been derived to analyze the IR data to determine the dimerization constant consistently. Equation 10 is to be used to fit the integrated absorbances of the monomer band to obtain the molar monomer absorptivity, epsilon(m), and dimerization constant, K; Eq. 17 is to be used to fit the integrated absorbances of the dimer bands to obtain the molar dimer absorptivity, epsilon(d), and dimerization constant, K. Thus the same dimerization constant can be independently determined either from the monomer band or from the dimer band. The discrepancy between the two determined values Provides an assessment of the consistency of determination. The monomer-dimer self-association of 2,2-dimethyl-3-ethyl-3-pentanol in the solvent of carbon tetrachloride was chosen to demonstrate the utility of these two equations.
A Laplace transform solution for tracer tests in a radially convergent flow field with upstream dispersion
(1996-09-01)
Chen, JS
;
Liu, CW
;
Chen, CS
;
Yeh, HD
;
環境工程研究所
When tracers are introduced into an injection borehole, noticeable concentration gradients at the injection well may cause a backward spreading of the initial plume during radially convergent tracer tests. Based on this concept a non-rigorous mathematical model is developed to estimate the effect of backward spreading. The injection well with an instantaneous slug input is treated as a mathematical source and the initial plume at the injection well is allowed to move upstream. The model assumes that advection and longitudinal dispersion are the transport mechanisms in a radially converging how field. The Laplace transform solution for solute concentration in an infinite porous medium is obtained using the method of Green's function. Breakthrough curves are computed by numerically inverting the Laplace transform solution. As compared with the solution of Moench, it is concluded that the presence of backward movement of initial plume yields a decrease of peak concentration and spreading out of breakthrough curve tails. This effect is significant for small Peclet numbers and can be neglected for large Peclet numbers. A field tracer test is carried out to demonstrate the applicability of the model. The experimental data are fitted with the type curves of this study, and those of Moench's study, to determine dispersivity and aquifer porosity. The results show that dispersivity values estimated by matching the two type curves are different. Because it neglects backward dispersion, Moench's solution overestimates the dispersivity and effective aquifer porosity.
A Laplace transform solution for tracer tests in a radially convergent flow field with upstream dispersion
(1996-09-01)
Chen, JS
;
Liu, CW
;
Chen, CS
;
Yeh, HD
;
環境工程研究所
When tracers are introduced into an injection borehole, noticeable concentration gradients at the injection well may cause a backward spreading of the initial plume during radially convergent tracer tests. Based on this concept a non-rigorous mathematical model is developed to estimate the effect of backward spreading. The injection well with an instantaneous slug input is treated as a mathematical source and the initial plume at the injection well is allowed to move upstream. The model assumes that advection and longitudinal dispersion are the transport mechanisms in a radially converging how field. The Laplace transform solution for solute concentration in an infinite porous medium is obtained using the method of Green's function. Breakthrough curves are computed by numerically inverting the Laplace transform solution. As compared with the solution of Moench, it is concluded that the presence of backward movement of initial plume yields a decrease of peak concentration and spreading out of breakthrough curve tails. This effect is significant for small Peclet numbers and can be neglected for large Peclet numbers. A field tracer test is carried out to demonstrate the applicability of the model. The experimental data are fitted with the type curves of this study, and those of Moench's study, to determine dispersivity and aquifer porosity. The results show that dispersivity values estimated by matching the two type curves are different. Because it neglects backward dispersion, Moench's solution overestimates the dispersivity and effective aquifer porosity.
Accurate determination of dimerization constants from IR study of monomer-dimer self-association: 3-ethyl-2-methyl-3-pentanol in carbon tetrachloride as an example
(2004-10-01)
Chen, JS
;
Kao, DY
;
應用化學系
;
Department of Applied Chemistry
The monomer-dimer self-association of 3-2-methyl-pentanol in CCl4 at four different temperatures has been studied using IR spectroscopy. The spectral band of the OH fundamental stretching for a free monomer and that for a hydrogen-bonded dimer were resolved, and their respective integrated absorbances were calculated. The integrated absorbances of the monomer band for various concentrations at a given temperature were then employed based on Eq. 9 to obtain the molar absorptivity of the monomer band and the dimerization constant at that temperature. Similarly, those of the dimer band were employed based on Eq. 13 to determine the molar absorptivity of the dimer band and the dimerization constant at that temperature. Since the same dimerization constant can be determined independently either from the monomer band or from the dimer band, the discrepancy between the two determined values can serve as a criterion of the goodness of the determination. The standard enthalpy and entropy of the dimerization were also obtained from a van't Hoff plot for dimerization constants at different temperatures.
Characteristics of low-temperature-prepared (Ba, Sr)TiO3 films post treated by novel excimer laser annealing
(2002)
Shye, DC
;
Chiou, BS
;
Hwang, CC
;
Chen, JS
;
Su, IW
Thin (Ba0.5Sr0.5)TiO3 (BST) films were sputtered on Pt[FiN/Ti/Si multilayer substrates at very low temperature (150degrees C). A novel process, using wavelength 248-nm KrF excimer laser annealing (ELA), has been undertaken to implement barium strontium titanate (BST) films at a low process temperature of 300degrees C. The crystallinity and dielectric constant are greatly improved after ELA treatment. In this work, the variation of texture was investigated. Besides, the escaped oxygen atoms from BST films were detected in-situ using a residual gas analyzer (RGA) during ELA process. Thus, the degradation of upper surface is strongly influenced by the laser energy fluence for an ELA-BST film.
Current-temperature characteristics of low-temperature-sputtered (Ba,Sr)TiO3 films post treated by rapid thermal annealing
(2002)
Shye, DC
;
Chen, JS
;
Kuo, MW
;
Chou, BCS
;
Jan, CK
This work reports the current-temperature characteristics of the low-temperature-sputtered (Ba0.8Sr0.2)TiO3 (BST) film post treated by rapid thermal annealing (RTA) in O-2 ambient. The top electrode was biased under negative/positive voltage to investigate the interface properties of the Pt/BST/Pt multifilm. As the results, the current density of the RTA-treated BST film was greatly reduced owing to compensation of oxygen vacancies. The RTA-treated BST thin film biased at negative voltage exhibits a negative temperature-coefficient-resistivity (NTCR) behavior, but, intriguingly, that biased at positive voltage reveals a positive temperature-coefficient-resistivity (PTCR) behavior. According to the leakage current analysis, the Schottky emission dominates the negative biased current at upper interface, but the Heywang barrier scattering confines the positive biased current.
Dependence of polarization on temperature coefficient resistance of (Ba, Sr)TiO3 thin films post-treated by RTA
(2003-04-01)
Shye, DC
;
Chiou, BS
;
Kuo, MW
;
Chen, JS
;
Chou, BCS
The temperature coefficient of resistance (TCR) characteristics of Pt/(Ba0.8Sr0.2)TiO3 (BST)/Pt thin-film resistors are studied for the BST films with rapid thermal annealing (RTA) treatments. The polarizations induced by bias voltages greatly influence the TCR characteristics. The RTA-treated BST thin film exhibits negative TCR (NTCR) behavior at a negative voltage, but, intriguingly, positive TCR (PTCR) behavior at a positive voltage. According to the leakage current analysis, Schottky emission dominates the negatively biased current at the upper interface, but Heywang barrier scattering confines the positive biased current. (C) 2003 The Electrochemical Society.
Effect of rapid thermal annealed TiN barrier layer on BST capacitors prepared by RF magnetron cosputter system at low substrate temperatures
(2000-12-01)
Hwang, CC
;
Jaing, CC
;
Lai, MJ
;
Chen, JS
;
Huang, S
This work reports on rapid-thermal-annealed TiN as a barrier for Pt/BST/Pt/TiN/Ti/Si capacitors. Experimental results indicate that the diffusion of Ti and Si from the Ti adhesion layer and Si plug, respectively, degrade the capacitor for the gigabit dynamic random access memories (DRAMs) using barium strontium titanate (BST) as a dielectric material. Although the diffusion barrier TiN between the bottom electrode Pt and Ti adhesion layer has been conventionally used to release the issue, the interdiffusion of Ti and Si occurs due to the thermal budget of the BST deposition. A rapid thermal annealing process is applied to the as-deposited TiN barrier against the interdiffusion. Excellent electrical characteristics, including high dielectric constant (epsilon (r) = 320), low leakage current (1.5 x 10(-8) A/cm(2)) under 0.1 MV/cm, and a lifetime greater than 10 years under 1.5 MV/cm are obtained. Our results further demonstrate that the proposed technique is highly promising for future high-density DRAMs. (C) 2000 The Electrochemical Society. S1099-0062(00)07-005-X. All rights reserved.
Effect of rapid-thermal-annealed TiN barrier layer on the Pt/BST/Pt capacitors prepared by RF magnetron co-sputter technique at low substrate temperature
(2001-01-01)
Hwang, CC
;
Juang, MH
;
Lai, MJ
;
Jaing, CC
;
Chen, JS
This investigation reports the effect of rapid-thermal-annealing (RTA) on metallic barrier TiN against the interdiffusions of Ti and Si into barium strontium titanate (BST) in Pt/BST/Pt/TiN/Ti/Si capacitors. In the integration of BST capacitors, the thermal budget of the BST deposition would cause the inter-diffusions of Ti and Si from Ti adhesion layer and Si plug respectively. This event would degrade the BST capacitors. To address this issue. rapid-thermal-annealed TiN barriers were deposited between the bottom electrode Pt and adhesion layer Ti. Optimal RTA condition for TiN were found ill this: experiment. Excellent electrical characteristics of Pt/BST/Pt/TiN/Ti/Si capacitors. including high dielectric constant (epsilon (r) = 320). low leakage current (1.5 x 10(-8) A/cm(2)) under 0.1 MV/cm, and greater than 10 year lifetime under 1.6 MV/cm were obtained with Ar + O-2 mixed ambient at a low substrate temperature (300 degreesC). (C) 2001 Elsevier Science Ltd. All rights reserved.
Effect of TiN treated by rapid thermal annealing on properties of BST capacitors prepared by RF magnetron co-sputter system at low substrate temperature
(2000)
Teng, TH
;
Hwang, CC
;
Lai, MJ
;
Huang, SC
;
Chen, JS
In this work, (Ba0.7Sr0.3)TiO3 thin films on Pt/TiN/Ti/Si substrate were deposited by an RF magnetron co-sputter system at 300 degrees C in an Ar+O-2 mixed ambient. In the integration of BST capacitors, the diffusion barrier (TiN) under bottom electrodes is one of the key issues. To obtain a stable and excellent diffusion barrier against inter-diffusion between Pt and Si, as well as against being oxidized during BST deposition, TiN was treated by a rapid thermal annealing (RTA) process. Experimental results indicated that proper RTA treatments resulted in a superior TiN barrier layer. In addition, low substrate temperature during BST deposition suppressed the phenomena of inter-diffusion and barrier oxidation. Furthermore, Pt hillocking, another problem during BST deposition because of high thermal budget, was also solved by reducing substrate temperature during BST deposition. The MIM (Pt/BST/Pt) structure was used in the experiments for electrical properties measurement. High dielectric constant (epsilon (r)=300), low leakage current (1.5x10(-8) A/cm(2)) under 0.1MV/cm, and 10 year lifetime under 1.6MV/cm were achieved with an Ar+O-2 mixed ambient at a low substrate temperature (300 degrees C).
Effects of post-oxygen plasma treatment on Pt/(Ba,Sr)TiO3/Pt capacitors at low substrate temperatures
(2003-02-01)
Shye, DC
;
Hwang, CC
;
Lai, MJ
;
Jaing, CC
;
Chen, JS
We investigated how oxygen plasma post-treatment improves leakage characteristics of Pt/(Ba,Sr)TiO3 (BST)/Pt capacitors prepared by the radio-frequency (RF) cosputtering technique. Experimental results indicate that oxygen plasma treatment can effectively passivate the oxygen vacancies of (Ba,Sr)TiO3 (BST) films, thus decreasing the electric conduction paths of leakage currents. By this low-temperature (250degreesC), and short-duration (similar to5 min) process, the leakage current is reduced by as many as two orders of magnitude. The reliability characteristics of time-dependent dielectric breakdown (TDDB) are improved as well. However, the usage of oxygen plasma treatment is not unrestricted. Plasma treatment for an extended period (more than 10 min) degrades both the leakage and reliability characteristics, due to plasma damage. Excellent electrical characteristics, including low leakage current (1.5 x 10(-8) A/cm(2)) under 0.1 MV/cm, high dielectric constant (288), and a lifetime longer than 10 years under 2 MV/cm can be achieved. Therefore, the proposed technique for as-deposited BST films is a highly promising means of improving the electrical characteristics of BST thin films.
Effects of thermal stabilities for the ultra thin chromium layers applied on (Ba,Sr)TiO3 thin films
(2004)
Kuo, MW
;
Shye, DC
;
Chiou, BS
;
Chen, JS
;
Cheng, HC
This work reports the temperature-electric properties for the (Ba,Sr)TiO3(BST) thin film capacitor using the multi-film structure of BST/ultra-thin-chromium(Cr) layer/BST. The BST(200 nm)/Cr(1-3 nm)/BST(200 nm) multi-films reveal excellent properties in the thermal stabilities of dielectric property, low leakage current and less power dissipation.
Graphical method for the determination of the complex NMR shift and equilibrium constant for a hetero-association accompanying self-associations
(1997-08-01)
Lin, CC
;
Fang, CY
;
Kao, DY
;
Chen, JS
;
應用化學系
We describe a novel graphical method which, in conjunction with the previously proposed graphical determination of mono;ner shift, dimer shift, and dimerization constant for self-association, allows us to determine the complex shift and equilibrium constant for a hetero-association, A + B reversible arrow AB, accompanying self-associations, A + A reversible arrow A(2), and B + B reversible arrow B-2. The merit of the new method includes the removal of the restrictions imposed on the conventional Benesi-Hildebrand (B-H) plot: (1) that the concentration of one component must be much less than that of the other; (2) that there be no accompanying self-association, The simultaneous equilibrium of the self-association of 2-pyrrolidone (A) and that of 4-methyl-alpha-pyrrolidone (B) and the hetero-association between A and B in acetonitrile-d(3) at 25 degrees C is studied. The inappropriateness of the B-H plot in dealing with this case is also pointed out.
Graphical method for the determination of the complex NMR shift and equilibrium constant for a hetero-association accompanying self-associations
(1997-08-01)
Lin, CC
;
Fang, CY
;
Kao, DY
;
Chen, JS
;
交大名義發表
We describe a novel graphical method which, in conjunction with the previously proposed graphical determination of mono;ner shift, dimer shift, and dimerization constant for self-association, allows us to determine the complex shift and equilibrium constant for a hetero-association, A + B reversible arrow AB, accompanying self-associations, A + A reversible arrow A(2), and B + B reversible arrow B-2. The merit of the new method includes the removal of the restrictions imposed on the conventional Benesi-Hildebrand (B-H) plot: (1) that the concentration of one component must be much less than that of the other; (2) that there be no accompanying self-association, The simultaneous equilibrium of the self-association of 2-pyrrolidone (A) and that of 4-methyl-alpha-pyrrolidone (B) and the hetero-association between A and B in acetonitrile-d(3) at 25 degrees C is studied. The inappropriateness of the B-H plot in dealing with this case is also pointed out.
Green's function and eigenvalue representations of time lag for membrane permeation transport
(2002-10-01)
Chen, JS
;
Chang, WY
;
應用化學系
;
Department of Applied Chemistry
Modeling membrane permeation transport by particles undergoing random walk over a one-dimensional lattice leads to a master equation, which describes the time dependence of particle concentration. With the stipulated conditions appropriate for absorptive permeation, the master equation is then solved in the Laplace domain to find the flux into the receiver, which in turn is used to formulate the time lag, t(L). It turns out t(L) can be represented by trace(A(-1)), where A is the transition matrix associated with the master equation. An analog to this representation for the continuous coordinate space is t(L) = (0)integral(h) G(x,x)dy, where G(x, x) is the Green's function associated with the steady-state diffusion equation with zero value at both boundaries 0 and h, and the source and observation points coinciding at x (0 < x < h). We have also provided a rigorous proof for this new Green's function representation of time lag. A bonus from the latter is that the time lag can be calculated t(L) = Sigma(n) 1/lambda(n) where lambda(n) is the eigenvalue of the transmission matrix. The directional symmetry of the time lag is easy to be interpreted on the basis of Green's function or eigenvalues representations.
Impact of MOSFET gate-oxide reliability on CMOS operational amplifiers in a 130-nm low-voltage CMOS process
(2005)
Chen, JS
;
Ker, MD
;
電機學院
;
College of Electrical and Computer Engineering
The effects of the gate-oxide reliability of MOSFETs on operational amplifiers were investigated with the two-stage and folded-cascode structures in a 130-nm low-voltage CMOS process. The tested operating conditions include unity-gain buffer (close-loop configuration) and comparator (open-loop configuration) under different input frequencies and signals. After overstress, the small-signal parameters, such as small-signal gain, unity-gain frequency, and phase margin, were measured to verify the impact of gate-oxide reliability on circuit performances of the operational amplifier. The gate-oxide reliability can be improved by the stacked configuration in the operational amplifier with folded-cascode structure. A simple equivalent device model of gate-oxide reliability for CMOS devices in analog circuits was investigated and simulated.
Interlayer growth and electrical behavior of Ta2O5/SiOxNy/Si gate stacks
(2004)
Lai, YS
;
Chen, JS
;
Wang, JL
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Growth and reaction of the interlayer (IL) between ultrathin Ta2O5 films and bare, and N2O or NH3 plasma-nitrided Si substrate, before and after rapid thermal oxidation (RTO), is examined by X-ray photoelectron spectroscopy. The IL thickness extracted from the attenuated Si 2p photoelectron signal shows that the thermal instability between Ta2O5 and Si causes the IL to grow further after RTO annealing. The SiOxNy layer formed on the N2O plasma-nitrided Si appears to provide better barrier efficiency in retarding the growth of IL. For current-voltage measurements, an anomalous saturated current is observed for as-deposited Ta2O5 films when stressed positive bias, presumably due to the film/substrate stress-induced Si bandgap widening. After RTO annealing, the leakage current through Ta2O5/IL stacks is higher under positive bias than under negative bias. Ta2O5 deposited on N2O-nitrided Si also exhibits the best leakage behavior among the three systems with the current of 1.7 x 10(-8) A/cm(2) at E = 2.0 MV/cm and 1.9 x 10(-7) A/cm(2) at E = +2.0 MV/cm. The correlation between leakage current as well as IL growth is also discussed. (C) 2004 The Electrochemical Society.
Low temperature radio-frequency-sputtered (Ba, Sr)TiO3 films on Pt/TiN/Ti/Si substrates with various oxygen/argon mixing ratios
(2003-02-01)
Shye, DC
;
Chiou, BS
;
Lai, MJ
;
Hwang, CC
;
Jiang, CC
(Ba, Sr) TiO3 (BST) films were fabricated on Pt/TiN/Ti/Si substrates by low temperature radio frequency magnetron cosputtering at 300degreesC. Material and electrical properties of BST films sputtered at low temperatures are significantly affected by the O-2/(Ar + O-2) mixing ratio (OMR). Plasma emission spectra indicate that the deposition rate declines at a higher OMR due to oxide formation on the target surface. The dielectric constant of the BST films can reach a maximum of 364 at 5% OMR. The ten-year lifetime of the time-dependent dielectric breakdown implies that the reliability of the capacitor can be enhanced at a higher OMR due to compensation of oxygen vacancies and smaller grain sizes. Current-voltage analysis indicates that the leakage current of the Pt/BST/Pt capacitor is limited by Schottky emission (SE)/Poole-Frenkel emission (PF) at a lower/higher applied field. The applied field boundary between SE and PF shifts toward higher field as OMR increases. Moreover, an energy band model was proposed and this leakage mechanism was discussed. (C) 2003 The Electrochemical Society.
Low-temperature process to improve the leakage current of (Ba, Sr)TiO3 films on Pt/TiN/Ti/Si substrates
(2000-12-15)
Hwang, CC
;
Lai, MJ
;
Jaing, CC
;
Chen, JS
;
Huang, S
In this study, we employed an oxygen plasma post-treatment to improve the leakage characteristics of Pt/(Ba, Sr)TiO3(BST)/Pt capacitors prepared by the RF cosputtering technique. Applying oxygen plasma treatment to BST thin films can effectively passivate the oxygen vacancies of the BST films, thus decreasing the electric conduction paths of leakage current. The leakage current is reduced by as many as two orders of magnitude by this low-temperature (250 degreesC) and short duration (similar to5 min) process. However, the usage of oxygen plasma treatment is not unrestricted. Plasma treatment over a long time (more than 10 min) degrades the leakage characteristics, due to plasma damage. Therefore, a proper oxygen plasma treatment for as-deposited BST films is desired to improve leakage characteristics of BST thin films.