Browsing by Author "Liu, CY"

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A new observation of the germanium outdiffusion effect on the hot carrier and NBTI reliabilities in sub-100nm technology strained-Si/SiGe CMOS devices
(2005)
Chung, SS
;
Liu, YR
;
Yeh, CF
;
Wu, SR
;
Lai, CS
In this paper, the evidence of SiGe layer induced trap generation and its correlation with enhanced degradation in strained-Si/SiGe CMOS devices have been reported for the first time. First, a new two-level charge pumping(CP) curve has been demonstrated to identify the Ge out-diffusion effect. Secondly, enhanced degradation in strained-Si devices has been clarified based on experimental results. Both n- and p-MOSFE's exhibit different extent of HC degradation effect. This is attributed to the difference in their mobility enhancement as well as additional traps coming from the Si/SiGe interface. Finally, temperature dependence of HC and NBTI has been examined for both strained-Si and bulk devices. Sophisticated measurement techniques, charge pumping and gated-diode (GD) measurements, have been employed to understand the generated interface traps. Results show that strained-Si device is less sensitive to the temperature and has a chance for better NBTI reliability if we have a good control of the strained-Si/SiGe interface, such as through low temperature gate oxide process or better S/D junction formation.
A novel four-mask-processed poly-Si TFT fabricated using excimer laser crystallization of an edge-thickened alpha-Si active island
(2004-06-01)
Chen, TF
;
Yeh, CF
;
Liu, CY
;
Lou, JC
;
電子工程學系及電子研究所
A novel four-mask-processed polycrystalline silicon thin-film transistor (poly-Si TFT) is fabricated using 50-pulse KrF excimer laser to crystallize an edge-thickened amorphous silicon (a-Si) active island without any shrinkage. This method introduces a temperature gradient in the island to enlarge grains from the edge, especially when the channel width is narrow. The grain boundaries across the width of the channel suppress the leakage current and the drain-induced barrier lowering. Moreover, the proposed poly-Si TFT with a channel length of L = 2 mum and a channel width of W = 1.2 mum possesses a high field-effect mobility of 260 cm(2)/Vs and an on/off current ratio of 2.31 x 10(8).
A simulated annealing algorithm for integration of shop floor control strategies in semiconductor wafer fabrication
(2003-09-01)
Sha, DY
;
Liu, CY
;
工業工程與管理學系
;
Department of Industrial Engineering and Management
The semiconductor manufacturing industry is one of the most important industries in Taiwan. Wafer fabrication is an essential process in semiconductor manufacturing. However, controlling the production system on the shop floor is extremely difficult owing to the complicated manufacturing process and reentrant characteristics. In this paper, the shop floor control (SFC) integration strategies (order review/release, dispatching, and rework strategies) in wafer fabrication are considered with using several performances. We reviewed the literature on SFC strategies in wafer fabrication. The proposed combination simulation and simulated annealing (SA) algorithm is presented for SFC strategies in wafer fabrication. The objective was to seek the near global optimum solution for the combination of SFC strategies for a specific performance indicator. From the results, the proposed methodology was found to perform well for combinations of SFC strategies using different performance indicators in wafer fabrication. However, no single combination of SFC strategies could satisfy all performance indicators. Hence, considering the trade-off among these production control strategies, a suitable strategy should be chosen based on the system control tactics. Considerable computational time was saved in this research.
An improved two-frequency method of capacitance measurement for SrTiO3 as high-k gate dielectric
(2002-09-01)
Lue, HT
;
Liu, CY
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An improved two-frequency method of capacitance measurement for the high-k gate dielectrics is proposed. The equivalent circuit model of the MOS capacitor including the four parameters of intrinsic capacitance, loss tangent, parasitic series inductance, and series resistance is developed. These parameters can be extracted by independently measuring the capacitor at two different frequencies. This technique is demonstrated for high-k SrTiO3 gate dielectrics and the results show that the calibrated capacitances are invariant over a wide range of frequency. In addition, the extracted loss tangent, inductance and resistance are independent on gate voltage and frequency. The effect of series resistance on the frequency dispersion of the capacitance can be also explained by this model. These results indicate that this modified technique can be incorporated in the routine capacitance-voltage (C-V) measurement procedure providing the physically meaningful data for the high-k gate dielectrics.
An investigation of inner light during Zen meditation using alpha-suppressed EEG and VEP
(2005)
Chang, KM
;
Liu, CY
;
Lo, PC
;
電控工程研究所
;
Institute of Electrical and Control Engineering
Sensitivity to light is a common experience during prayer or Zen meditation, in both western and eastern cultures. Higher levels of happiness and lower health insurance costs are typical for those who experience inner tight. In this report, the connection between the experience of inner light and Zen meditation is investigated by using EEG and flash visual evoked potential (F-VEP) recorded from the occipital site Oz. EEG results indicate that the experience of inner light during Zen meditation by experienced practitioners is also accompanied by a large amount of alpha-suppressed EEG. The F-VEP data also reflect shorter latency, and indicates a stronger and more sensitive visual response during Zen meditation. These data are also the typical physiological responses when the eyes are open during a rested conscious state, and thus provide a possible closer connection between Zen meditation and the sensitivity of inner light.
Bistable resistive switching of a sputter-deposited Cr-doped SrZrO3 memory film
(2005-06-01)
Liu, CY
;
Wu, PH
;
Wang, A
;
Jang, WY
;
Young, JC
Sputter-deposited Cr-doped SrZrO3-based metal-insulator-metal structures exhibited bistable resistive reversible switching as observed under bias voltage and voltage pulse. The ratio of resistance of the two leakage states (high-H, low-L) was about five orders of magnitude. The conduction of the L-state satisfied Frenkel-Poole emission and that of the H-state followed ohmic mechanism, causing the resistance ratio to decrease with increasing bias voltage. The transition time of H- to L-state was five orders of magnitude higher than that of L- to H-state. The transition from H- to L-state was the restricted part for reversible switching operation. The difference in transition time of the two states should be related to the respective conduction mechanisms.
Chaotic behaviors of bistable laser diodes and its application in synchronization of optical communication
(2001-10-01)
Wang, WC
;
Hwang, TM
;
Juang, C
;
Juang, J
;
Liu, CY
Period-doubling routes to chaos behavior in bistable laser diodes is examined numerically, An external sinusoidal electronic drive is injected to generate chaotic light output. Phase portrait, Poincare map, bifurcation diagram, and Lyapunov exponent are then calculated to assert the existence of chaos. Furthermore, according to Pecora and Carroll's theory, a drive-response system is constructed by using the bistable laser diodes to mask the sinusoidal electronic signal with chaotic light. Synchronization can be achieved for optical simplex and duplex transmissions using bistable laser diodes. The proposed synchronization scheme between two separate chaotic systems provides a key step toward optical chaotic communication.
Correlation between deep depletion and current-voltage saturation of SrTiO3 gate dielectric capacitor
(2004)
Liu, CY
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
SrTiO3 (STO) gate dielectrics were deposited on p-type silicon substrate by radio-frequency (rf) magnetron sputtering in an Ar-O-2 and Ar-N-2 mixed ambient to form metal/insulator/semiconductor (MIS) capacitor to investigate capacitance-voltage (C-V) and current-voltage (I-V) characteristics. Schottky emission and Fowler-Nordheim tunneling mechanisms were responsible for the leakage current of nitrogen-grown STO-based MIS capacitors at the low and high electric field under accumulation condition, respectively, while the generation current dominated the leakage mechanism under the inversion condition due to the highly leaky insulator and the lack of electrons. The depletion width under the inversion condition would broaden to generate more electrons to maintain the leakage current and lead to capacitance decreasing under higher bias voltage, which is called as deep depletion. Therefore, the deep depletion and leakage current saturation under inversion condition would occur at the same time. The correlation between the deep depletion and the leakage mechanism in STO-based gate dielectric capacitor under inversion condition was used to extract the generation lifetime of silicon substrate. The normalized C-V measurements at 1 kHz under illumination were also made to examine the results of extracted generation lifetime. The extracted generation lifetime could provide a simple method to judge the quality of silicon substrates. (C) 2004 Elsevier Ltd and Techna Group S.r.1. All rights reserved.
Deep depletion phenomenon of SrTiO3 gate dielectric capacitor
(2004-05-15)
Liu, CY
;
Chen, BY
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
SrTiO3 (STO) thin films were deposited on p-type silicon substrate by radio-frequency (rf) magnetron sputtering in an Ar-O-2 and Ar-N-2 mixed ambient to form metal/insulator/semiconductor (MIS) structure. We found the Schottky emission and Fowler-Nordheim tunneling mechanisms as responsible for the leakage current in the STO-based MIS structures at low and high electric fields under negative bias voltage, respectively. On the other hand, it was also observed that the generation current dominated the leakage mechanism at the high electric field under positive bias voltage due to the highly leaky insulator and lack of electrons. To maintain the leakage current at the higher electric field, the depletion width would broaden to generate more electrons, which is called deep depletion. Therefore, deep depletion was induced by high leakage current density under positive bias voltage. We also investigated the correlation between deep depletion and the leakage mechanism in STO-based gate dielectric capacitors under positive bias voltage to extract the generation lifetime of silicon substrates. The extracted generation lifetime can be used to examine the quality of silicon substrates after different processing conditions. (C) 2004 American Institute of Physics.
Dielectric characteristics of nanocrystalline Ag-Ba0.5Sr0.5TiO3 composite thin films
(2004-08-16)
Jayadevan, KP
;
Liu, CY
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Nanocrystalline Ag-Ba0.5Sr0.5TiO3 (Ag-BST) composite thin films are deposited on Pt/Ti/SiO2/Si substrates by a sol-gel method. The voltage-dependent capacitance (C-V) and dielectric loss of the films decrease with increasing Ag up to 2 mol % due to a series configuration involving low dielectric interface layers and dense microstructures. The evidence for asymmetric distribution of charge carriers in the Ag-BST film is derived from C-V measurements. The dielectric tunability of BST film with 1 mol % Ag is comparable to that of pure BST. (C) 2004 American Institute of Physics.
Effects of nitridation of silicon and repeated spike heating on the electrical properties of SrTiO3 gate dielectrics
(2002-12-02)
Liu, CY
;
Lue, HT
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Electrical properties of SrTiO3 (STO) gate dielectrics on Si substrates grown by rf-magnetron sputtering were studied. We employed the surface nitridation and repeated spike heating to improve the interfacial properties of STO/Si. The nitrogen was moderately incorporated at the interface by first growing a thin SiON layer and then removing this sacrificial layer before growing STO gate dielectric. The experimental results indicate that this nitridation treatment may retard the formation of thin interfacial layer during the high-temperature growth of STO gate dielectric and consequently decrease the equivalent oxide thickness (EOT) by about 10% toward 24% at various deposition pressures. The STO gate dielectric with this nitridation treatment exhibited slightly lower leakage current at an accumulation region and nearly 2 orders of magnitude lower leakage current at an inversion region. The repeated spike heating technique was also employed to deposit a STO gate dielectric at repeated oscillating temperatures. The results show that this thermal treatment reduced the interfacial trap states and the leakage current was also reduced by about 1 order of magnitude at the same EOT. (C) 2002 American Institute of Physics.
Electrical properties of resistance switching V-doped SrZrO3 films on textured LaNiO3 bottom electrodes
(2006-03-21)
Liu, CY
;
Wang, A
;
Jang, WY
;
Tseng, TY
;
電子工程學系及電子研究所
Sputter-deposited V-doped SrZrO3 (SZO) films were deposited on textured LaNiO3 (LNO) bottom electrodes to investigate the resistance switching properties and reliabilities. The microstructures of the SZO and LNO films were characterized by x-ray diffraction. The resistance of the AI/V-doped SZO/LNO sandwich structures can be reversibly switched by operating with dc bias voltages or voltage pulses. The device with [100] orientated SZO film had better resistance switching properties and the resistance ratio was more than 1000. The effect of thermal treatment on resistance switching properties was investigated and different behaviour of the two leakage-states was found. Finally, the reliability of the device was also investigated. The device with the properties of reversible resistance switching and non-destructive readout is suitable for nonvolatile memory application.
Electrical properties of sputter deposited SrTiO3 gate dielectrics
(2004)
Liu, CY
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We report the electrical properties of gate dielectric SrTiO3 (STO) thin films on Si substrates grown by radio-frequency magnetron sputtering. The interfacial layer between STO and Si degrades the performance of the gate dielectric. We used SiON as a sacrificial layer for incorporating nitrogen into Si substrate surface, which can retard the formation of interfacial layer during the high temperature growth of STO gate dielectric. The polycrystalline STO film grown on nitrogen incorporated Si substrate exhibited lower leakage current due to better interfacial properties and higher dielectric constant. The repeated spike heating technique was also employed to deposit polycrystalline STO film for improving the thermal uniformity of the wafer, which leads to lower gate leakage current. The processing parameters including working pressure, oxygen mass ratio and plasma power also show obvious effect on the electrical properties of the films. (C) 2003 Elsevier Ltd. All rights reserved.
Memory effect of sol-gel derived V-doped SrZrO3 thin films
(2006-01-03)
Liu, CY
;
Chuang, CC
;
Chen, JS
;
Wang, A
;
Jang, WY
V-doped SrZrO3 (SZO) thin films on LaNiO3/SiO2/Si substrate are synthesized by sol-gel method to form metal-insulator-metal (MIM) sandwich structure. The physical and electrical properties of the MIM device are studied. The structure and surface morphology of the SZO films are also characterized by X-ray diffraction and scanning electron microscopy. Such a device has the bistable switching properties of current-voltage characteristics. The resistive switching between high state and low state can also be operated with voltage pulses. The device with the properties of long retention time and non-destructive readout is expected to be suitable for nonvolatile memory application. (c) 2005 Elsevier B.V. All rights reserved.
Metallurgical reactions of Sn-3.5Ag solder with various thicknesses of electroplated Ni/Cu under bump metallization
(2005-10-01)
Huang, CP
;
Chen, C
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Liu, CY
;
Lin, SS
;
Chen, KH
Nickel has been widely used as an under-bump metallization (UBM) material in the microelectronics industry. The solid-state reaction between the eutectic SnAg solder bumps and three thicknesses of Ni/Cu UBM was investigated, with 5 mu m-Cu/3 mu m-Ni, 3 mu m-Cu/2 mu m-Ni, and 0 mu m-Cu/1 mu m-Ni. It was found that the shear strength of the solder bumps decreased after the solid-state aging at 150 degrees C for 200 h, and it did not change much after it was prolonged for 500 and 1000 h. Aging of the Ag3Sn intermetallic compound (IMC) and grain growth of the solder are responsible for the decrease in the shear strength. Furthermore, the shear test results indicated that the fracture mode switched from ductile to brittle for the solder bumps with 1 mu m Ni after aging longer than 200 h, causing the strength of the solder to decrease abruptly. This is attributed to the consumption of the peripheral Ni layer after the solid-state aging for 1000 It. The Ni consumption rate was measured to be 0.02 mu m/h(1/2) at 150 degrees C.
Structural and biochemical evidence of mitochondrial depletion in pigs with hypertrophic cardiomyopathy
(2003-06-01)
Lin, CS
;
Sun, YL
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Liu, CY
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生物科技學系
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Department of Biological Science and Technology
Pig hearts with naturally occurring hypertrophic cardiomyopathy (HCM) were isolated to investigate the effects of mitochondrial deficiency at biochemical and molecular levels. Enzyme activities of mitochondrial-encoded cytochrome c oxidase and NADH dehydrogenase in the HCM hearts (n = 12) were lower than that in the controls (n = 12) by 41 +/- 29% (P < 0.01) and 43 +/- 21% (P < 0.001), respectively. Additionally, Southern blot analysis was conducted to quantify the relative amount of mitochondrial DNA (mtDNA) from the HCM and controls. The relative amount of mtDNA in the HCM hearts was significantly 57 +/- 19% (P < 0.001) lower than that in the controls. Both mitochondrial enzyme deficiency and mtDNA depletion were significantly correlated with the degree of cardiac hypertrophy judged based on the ratio of heart/body weight. In conclusion, our results reveal that a secondary effect of tissue-specific mtDNA depletion and mitochondrial dysfunction is in response to the LICK © 2003 Elsevier Science Ltd. All rights reserved.
Subcarrier multiplexing by chaotic multitone modulation
(2003-10-01)
Juang, C
;
Huang, ST
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Liu, CY
;
Wang, WC
;
Hwang, TM
Subcarrier multiplexing by chaotic multitone modulation is investigated. Optical chaotic light can be achieved by injecting multiple subcarriers into a self-pulsating laser diode. Synchronization between two identical chaotic systems (drive and response) can be implemented provided that the conditional Lyapunov exponents are all negative. By adding amplitude modulation (AM) signals to each subcarrier, the two systems become asymptotically synchronized. The AM signals in each subcarrier can be recovered by the introduction of a filtering process where the Lyapunov exponent of the synchronized error function matches the cutoff frequency of a first order low pass filter.
Surface chemical and leakage current density characteristics of nanocrystalline Ag-Ba0.5Sr0.5TiO3 thin films
(2005-09-01)
Jayadevan, KP
;
Liu, CY
;
Tseng, TY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Nanocrystatfine chi Ag-(1-x)Ba0.5Sr0.5TiO3(Ag-BST, 0 <= x <= 0.1, where x is the mole fraction of Ag) thin films have been deposited on Pt/Ti/SiO2/Si substrates by a sol-gel method. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS). The core-level XPS of oxygen (O1s) of the Ag-BST films indicate that an optimum amount of Ag (x = 0.02 or 2 mol%) enhances the binding energy of oxygen, possibly through a mechanism in which the electrophilic oxygen dissociates from the Ag surface and fills the oxygen vacancies. Similarly, the binding energy of Ag (Ag3d) shows a shift toward a higher value with increasing Ag up to 4 mol%, probably because of the chemical shift of Ag in BST along the surface layers, surface relaxation, or changes in the Fermi level of small Ag particles in the solid solution range of Ag in BST fillms (x <= 0.04). The leakage current density of 2 mol% Ag-added BST (similar to 10(-6) A/cm(2)) is less by about an order of magnitude than pure BST at an electric field of 200 kV/cm. A defect model is proposed to explain the observed leakage current density of Ag-BST films satisfactorily.