Browsing by Author "Ho, Chia-Cheng"

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Dielectric anisotropy in the integration of Cu-SiLK (TM) system
(2008-01-01)
Tseng, Hal-Sin
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Chiou, Bi-Shiou
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Wu, Wen-Fa
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Ho, Chia-Cheng
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電子工程學系及電子研究所
As device density and performance continue to improve, low dielectric constant (k) materials are needed for interlevel dielectric (ILD) applications. The dielectric anisotropy of polymers with low k is an important property to consider for developing ILD. This is on-going research on the integration aspects of Cu-SiLK(TM) system. In this study, the dielectric anisotropy of SiLK polymer was evaluated with two test structures: the metal-insulator-metal (MIM) parallel capacitor structure for the out-of-phase dielectric constant (k(perpendicular to)) and comb-and-serpentine interdigitated structure for the in-plane dielectric constant (k(parallel to)). A k(perpendicular to) of 2.65, a k(parallel to) of 2.75, and a dielectric anisotropy of 3.77% were obtained for SiLK. However, SiLK exhibits larger leakage current as compared to amorphous SiO2 films. The reliability issue on the integration of Cu-SiLK is discussed. (C) 2007 Elsevier B.V. All rights reserved.
Effect of plasma treatment on the microstructure and electrical properties of MIM capacitors with PECVD silicon oxide and silicon nitride
(2007-02-01)
Ho, Chia-Cheng
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Chiou, Bi-Shiou
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電子工程學系及電子研究所
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Innovative Packaging Research Center
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Department of Electronics Engineering and Institute of Electronics
Metal-insulator-metal (MIM) capacitors with plasma enhanced chemical vapor deposited (PECVD) nitride exhibit trap-induced dispersive behavior and electrical hysteresis, which lead to degradation in capacitor linearity at low frequencies. The dominant defect was suggested to be silicon dangling bonds originated from nitrogen deficiency. Previous methods to eliminate the dispersive behavior and electrical hysteresis include use of oxide-nitride-oxide (ONO) stacks and/or plasma pre-treatment of silicon substrate before nitride deposition [Van Huylenbroeck S, Decoutere S, Venegas R, Jenei S, Winderickx G (2002) IEEE Electron Device Lett 23:191; Lau WS (1990) Jpn J Appl Phys 29:L690]. In this study, the plasma post-treatment method was employed; MIM capacitors with PECVD oxide and nitride were treated with N2O and SiH4/NH3 plasma, respectively, after deposition of the dielectric layer. No apparent change in film microstructure is observed after plasma treatment. Plasma post-treatment is effective in eliminating the electrical hysteresis shift of the nitride capacitors. Fourier transform infrared (FTIR) absorption spectra suggest an increase of the Si-H bond after SiH4/NH3 plasma bombardment of the nitride films. Auger depth profiling indicates a slight increase of nitrogen to silicon ratio after plasma treatment. The increase of the Si-H bonds as well as the raise of nitrogen to silicon ratio are two possible causes for the elimination of the hysteresis shift of the plasma-treated nitride capacitors. The time dependent dielectric breakdown testing indicates a decrease in both the leakage current and the lifetime of the MIM capacitors treated with plasma. Possible dielectric degradation mechanism is explored.
Effect of size and plasma treatment and the application of Weibull distribution on the breakdown of PECVD SiNx MIM capacitors
(2008-01-01)
Ho, Chia-Cheng
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Chiou, Bi-Shiou
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電子工程學系及電子研究所
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Innovative Packaging Research Center
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Department of Electronics Engineering and Institute of Electronics
The dielectric breakdown field is one of the important concerns for device reliability. The breakdown of dielectric is originated at a fatal flaw that grows to cause failure and can be explained by the weakest-link theory. In this study, metal-insulator-metal (MIM) capacitors with plasma enhanced chemical vapor deposited (PECVD) SiNx are prepared. Ammonia (NH3) plasmas are applied after the deposition of the dielectric SiNx. The Weibull distribution function, which is based on the weakest-link theory, is employed to analyze the effect of the electrode area as well as the plasma treatment on the breakdown of the MIM capacitors. The time dependent dielectric breakdown testing indicates a decrease in both the leakage current and the lifetime of the MIM capacitors treated with plasma. Possible dielectric degradation mechanisms are explored. (C) 2007 Elsevier B.V. All rights reserved.
Effect of Top Electrode Materials on the Nonvolatile Resistive Switching Characteristics of CCTO Films
(2011-03-01)
Lin, Chun-Chieh
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Chang, Yi-Peng
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Ho, Chia-Cheng
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Shen, Yu-Shu
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Chiou, Bi-Shiou
A novel material CaCu(3)Ti(4)O(12) (CCTO) for resistive random access memory (RRAM) application was prepared by sol-gel spin-coating method. Our previous studies indicated that the CCTO possesses stable resistive switching behavior. In this work, the effects of the top electrode (TE) material on the resistive switching characteristics of CCTO films are investigated. It indicates the work function of the TE is an important factor on the resistive switching properties. Successive resistive switching was observed for electrode materials of Ni, Pd, and Pt. Furthermore, optimized consideration of the electrode material for RRAM is also studied.
Effects of annealing temperature on the resistance switching behavior of CaCu(3)Ti(4)O(12) films
(2008-12-01)
Shen, Yu-Shu
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Chiou, Bi-Shiou
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Ho, Chia-Cheng
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電子工程學系及電子研究所
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Innovative Packaging Research Center
In this study, a novel material CaCu(3)Ti(4)O(12) (CCTO), for resistance random access memory application, was prepared by sol-gel method and annealed at various temperatures. The crystallinity and microstructure of CCTO film, improve as annealing temperature increases. The CCTO films annealed at 800 degrees C and above endure more switching cycles (> 1000) and exhibit a small degradation of the resistance ratio between the high resistance state and the low resistance state than those annealed at 700 degrees C do. The correlation between resistance switching behaviors and film microstructure is discussed. (C) 2008 Elsevier B.V. All rights reserved.
Effects of annealing temperature on the resistance switching behavior of CaCu3Ti4O12 films
(2008-12-01)
Shen, Yu-Shu
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Chiou, Bi-Shiou
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Ho, Chia-Cheng
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電子工程學系及電子研究所
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Innovative Packaging Research Center
In this study, a novel material CaCu3Ti4O12 (CCTO), for resistance random access memory application, was prepared by sol-gel method and annealed at various temperatures. The crystallinity and microstructure of CCTO film, improve as annealing temperature increases. The CCTO films annealed at 800 degrees C and above endure more switching cycles (> 1000) and exhibit a small degradation of the resistance ratio between the high resistance state and the low resistance state than those annealed at 700 degrees C do. The correlation between resistance switching behaviors and film microstructure is discussed. (C) 2008 Elsevier B.V. All rights reserved.
Effects of plasma treatment on the high frequency characteristics of Cu/Ta/hydrogen silsesquioxane (HSQ) system and electrical behaviors of Cu/Ta/HSQ/Pt MIM capacitors
(2007-04-01)
Ho, Chia-Cheng
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Chiou, Bi-Shiou
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電子工程學系及電子研究所
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Innovative Packaging Research Center
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Department of Electronics Engineering and Institute of Electronics
With the increasing of the operating frequencies, insertion loss, signal propagation delay, and parasitic coupling capacitance become the significant problems. Small capacitance (C) between interconnects is required to reduce the crosstalk, insertion loss, and RC delay associated with the metal interconnect system. Therefore, the interconnect with low dielectric constant (k) material is required. Implementation of Cu/low-k dielectric is used for reducing insertion loss, RC delay, crosstalk noises, etc. In this work, Cu-hydrogen silsesquioxane (HSQ) systems are studied. Ammonia (NH3) plasma is employed for the nitridation of HSQ. The effects of NH3 plasma treatments on the high frequency characteristics (100 MHz to 20 GHz) of the interconnect structure Cu/Ta/HSQ and electrical behaviors of Cu/Ta/HSQ/Pt MIM capacitors are evaluated. Auger electron spectroscopy (AES) results suggest the diffusion of oxygen and copper atoms during copper annealing. This raises resistance of Cu interconnect and increases the conductance of the HSQ films. Hence, 400 degrees C-annealed Cu/Ta/HSQ interconnect systems become lossy at high frequencies (> 2 GHz). Ammonia (NH3) plasma bombardments break some of the Si-H bonds and the resulting dangling Si bonds increase the moisture absorption. Meanwhile, NH3 plasma treatments reduce the leakage current by passivating the Si dangling bond and forming silicon nitride. The absorption of moisture and/or the formation of SiNx result in high dielectric constant of HSQ after prolonged NH3 plasma bombardment. The dielectric constant of HSQ decreases and then increases with the increase of NH3 plasma treatment time and a minimum dielectric constant of 2.2 is obtained after 50 s NH3 plasma treatment at 200 W. Among various specimens in this study, the smallest insertion loss is 1.97 dB/mm at 20 GHz for the 400 degrees C-annealed Cu/Ta/HSQ (NH3-plasma-treated for 50 s). Appropriate NH3-plasma bombardment helps to form a thin SiNx barrier layer which prevents the diffusion of oxygen without increasing the dielectric constant of the Cu-HSQ interconnect system. The leakage currents versus electric field characteristics suggest that a Schottky emission dominate conduction mechanism. (c) 2007 Elsevier B.V. All rights reserved.
Impedance Spectroscopy of CaCu(3)Ti(4)O(12) Films Showing Resistive Switching
(2009-01-01)
Shen, Yu-Shu
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Ho, Chia-Cheng
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Chiou, Bi-Shiou
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電子工程學系及電子研究所
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Innovative Packaging Research Center
CaCu(3)Ti(4)O(12) (CCTO), for resistance random access memory (RRAM) application, was prepared by the sol-gel method. Our preliminary study indicates that CCTO possesses the resistive switching behaviors of RRAM. In this work, the resistance switching characteristics of CCTO films were investigated. The impedance spectroscopy was applied to CCTO films during the switching cycle. Based on the results observed by impedance spectroscopy, the conduction mechanisms of the CCTO RRAMs at the original, ON, and OFF states were explored.
Impedance Spectroscopy of CaCu3Ti4O12 Films Showing Resistive Switching
(2009-01-01)
Shen, Yu-Shu
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Ho, Chia-Cheng
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Chiou, Bi-Shiou
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電子工程學系及電子研究所
;
Innovative Packaging Research Center
CaCu3Ti4O12 (CCTO), for resistance random access memory (RRAM) application, was prepared by the sol-gel method. Our preliminary study indicates that CCTO possesses the resistive switching behaviors of RRAM. In this work, the resistance switching characteristics of CCTO films were investigated. The impedance spectroscopy was applied to CCTO films during the switching cycle. Based on the results observed by impedance spectroscopy, the conduction mechanisms of the CCTO RRAMs at the original, ON, and OFF states were explored.
Improvement of electrical properties of Ba(0.7)Sr(0.3)TiO(3) capacitors with an inserted nano-Cr interlayer
(2008-07-01)
Ho, Chia-Cheng
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Chiou, Bi-Shiou
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Chang, Li-Chun
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
The metal-insulator-metal (MIM) capacitors were prepared with Ba(0.7)Sr(0.3)TiO(3)/Cr/Ba(0.7)Sr(0.3)TiO(3) (BST/Cr/BST) dielectric and Pt electrode. The multilayer BST/Cr/BST was sputtered onto Pt/Ti/SiO(2)/Si substrate. The presence of nano-Cr interlayer affects the electrical properties of the capacitors. The temperature coefficient of capacitance (TCC) of capacitors with 2 nm Cr is about 69% of that of capacitors without Cr. In a previous work, the formation of the TiO(2) secondary phase was found after the BST/Cr/BST dielectrics were annealed at 1023 K in O(2) atmosphere for 1 h. It is suggested that the nano-Cr interlayer as a catalyst leads to the TiO(2) formation during the annealing in O(2) atmosphere. The negative value of TCC of BST can be compensated by the positive TCC of TiO(2), and the temperature stability in the dielectric constant can be realized for capacitors with nano-Cr interlayer. The voltage stability of BST is also improved with the insertion of nano-Cr interlayer, and the quadratic coefficient in voltage coefficient of capacitance (VCC) of Pt/BST/Cr(2 nm)/BST/Pt is about 30% of that of the BST capacitor without Cr. The effects of Cr thickness on TCC, VCC, dissipation factor, and leakage current density of Pt/BST/Cr/BST/Pt parallel plate capacitors are investigated.
Managing News Coverage around Initial Public Offerings
(2010-03-01)
Ho, Chia-Cheng
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Huang, Chi-Ling
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Lin, Chien-Ting
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Lin, George Y. C.
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資訊管理與財務金融系註：原資管所+財金所
We examine opportunistic behavior of initial public offering (IPO) firms in Taiwan where they are required to disclose their own earnings forecasts and are unrestricted in releasing news around the offerings. We find that prior to the offerings, IPO firms tend to report higher earnings, disclose inflated earnings forecasts, and manage more good news. News management, however, emerges as the most predominant factor in aftermarket stock prices. In particular, IPO firms have a strong preference for releasing good news related to strategy/policy that may simply provide a vision of a firm's future. Furthermore, the news releases are often forward-looking when they are positive about the firms but tend to be realized when they are negative. IPO firms also tend to engage in more window dressing activities before a larger sale of IPO shares from existing shareholders or a larger decline in insiders' holdings. Our analysis shows that managerial optimism cannot fully account for their behavior.
Microstructure evolution and dielectric properties of Ba0.7Sr0.3TiO3 parallel plate capacitor with Cr interlayer
(2007-12-15)
Ho, Chia-Cheng
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Chiou, Bi-Shiou
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Chang, Li-Chun
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電子工程學系及電子研究所
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Innovative Packaging Research Center
The microstructure, crystalline phase, surface morphology, and dielectric properties of a sandwich structure of Ba0.7Sr0.3TiO3/Cr/ Ba0.7Sr0.3TiO3 (BST/Cr/BST) dielectric are characterized to understand the influence of the nano-Cr interlayer. BST dielectrics inserted with Cr film of thickness ranged from 2 nm to 15 nm all show the crystalline cubic phase. However, TiO2 layer is formed on the upper BST layer after the BST/Cr/BST dielectrics are annealed at 900 degrees C in O-2 atmosphere for one hour. In this study, TEM, AFM, SEM, X-ray diffraction, and AES are employed to investigate the microstructure evolution of the BST/Cr/BST dielectrics after annealing. The correlations between the microstructure and the dielectric properties of the Pt/BST/Cr/BST/Pt capacitors with various Cr thicknesses are explored. (C) 2007 Elsevier B.V. All tights reserved.
Reliability analysis using Weibull distribution on the breakdown of MIM capacitors
(2007)
Ho, Chia-Cheng
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Chiou, Bi-Shiou
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Rapidly growing performance and mixed-signal integration are driving the needs for product and component miniaturization in electronics application. The passive components show great potential for high frequency, high density, and low cost applications. Regarding to the capacitors, the dielectric breakdown field is one of the important concerns for the capacitor reliability. The breakdown of dielectric is originated at a fatal flaw that grows to cause failure and can be explained by the weakest-link theory. In this study, metal-insulator-metal (MIM) capacitors with plasma enhanced chemical vapor deposited (PECVD) silicon nitride and oxide are prepared. Ammonia (NH3) and N2O plasma are applied after the deposition of the dielectric silicon nitride and oxide layer, respectively. The Weibull distribution function, which is based on the weakest-link theory, is employed to analyze the effect of the electrode area as well as the plasma treatment on the breakdown of the MINI capacitors. The time dependent dielectric breakdown testing indicates a decrease in both the leakage current and the lifetime of the SiNx MIM capacitors treated after NH3 plasma treatment. Possible dielectric degradation mechanism is explored.
S-parameters-based high speed signal characterization of Al and Cu interconnect on low-K hydrogen silsesquioxane-Si substrate
(2007)
Ho, Chia-Cheng
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Chiou, Bi-Shiou
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
In this study, hydrogen silsesquioxane (HSQ) thin films are employed as the intermetal dielectric, and the high frequency characteristics of Al-HSQ and Cu/Ta-HSQ system are investigated and compared with those of Al-SiO2 system. The S-parameters of the interconnect are measured for insertion loss and crosstalk noise. The interconnect transmission parameters are extracted from the S-parameters. A figure of merit (FOM) is employed to evaluate the characteristics of the interconnect system at high frequencies (100MHz similar to 20GHz). It is found that the insertion losses are 2.01dB/mm, and 1.50dB/mm, 2.73dB/mm, 2.44dB/mm, and 1.66dB/mm at 10GHz, and 2.16dB/mm, 1.64dB/mm, 3.08dB/mm, 2.62dB/mm, and 1.82dB/mm at 20GHz for Al-SiO2, Al-HSQ, Al-HSQ (02 plasma), Cu/Ta-HSQ, and Cu/Ta-HSQ (NH3 plasma), respectively. The Al/HSQ system has better performance than the other ones do from 100MHz to 20GHz. The high frequency characteristics of Al and Cu interconnect with HSQ dielectrics are discussed.
Study on the voltage-controlled-oscillator circuit implemented with Al/HfO2/Si capacitors
(2007)
Pan, Tsai-Sheng
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Chang, Li-Chun
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Ho, Chia-Cheng
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Chiou, Bi-Shiou
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電子工程學系及電子研究所
Voltage controlled oscillator (VCO) is the most ubiquitous element in all communication systems, wired or wireless. In a wireless system the quality of the communication link is determined in large part by the characteristics of the VCO. The capacitance of metal/insulator/semiconductor (MIS) shows larger variation from the accumulation region to the depletion region. The dielectric constant of hafnium dioxide is larger (around 25) than that Of SiO2 (similar to 3.9). Al/Hafnium oxide (HfO2)/Si show a field dependent permittivity and can be used as a dielectric in voltage tunable capacitors. In this work, we used two types of tunable capacitor in the VCO(LC tank and Colpitts circuit) integrated within PCB: one is Al/HfO2/Si (HfO) capacitor, the other one is Philips BB 135 p-n junction capacitor for a control. The maximum MIS capacitance ratio is 4.25. The Al/HfO2/Si capacitors are then implemented as the varactor in the VCO circuit.
Thermal stability and electric properties of Ba0.7Sr0.3TiO3 parallel plate capacitor with nano-Cr interlayer
(2006-12-20)
Ho, Chia-Cheng
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Chiou, Bi-Shiou
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Chang, Li-Chun
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Chou, Chen-Chia
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Liou, Bo-Heng
A novel sandwich structure of Ba0.7Sr0.3TiO3/Cr/Ba0.7Sr0.3TiO3 (BST/Cr/BST) was sputtered onto Pt/Ti/SiO2/Si substrate. With the insertion of a Cr layer, the leakage currents are decreased and the thermal stability of the specimens is enhanced. Temperature coefficient of capacitance (TCC) of specimens with BST(200 nm)/Cr(2 nm)/BST(200 nm) multifilms can achieve about 83% lower than those with BST (400 nm) monolayer. However, the dielectric constant of the BST(200 nm)/Cr(2 nm)/BST(200 nm) multifilms decreases to about 37% of that BST monolayer. The leakage current densities under an electric field of 125 kV/cm at 90 degrees C are 4 x 10(-4) A/cm(2) and 9 x 10(-1) A/cm(2) for BST(200 nm)/Cr(2 nm)/BST(200 nm) and monolayer BST (400 nm), respectively. X-ray diffraction results indicate the formation of a CrO3 secondary phase after annealing at 700 degrees C or above in O-2 atmosphere. The root causes for the improvement of leakage currents and thermal stability with the insertion of nano-Cr interlayer are explored. The results show the insertion of Cr-nanolayer improves the electric properties for application in capacitors. (c) 2006 Elsevier B.V All rights reserved.
Thickness effects on the electrical characteristics of Ba0.7Sr0.3TiO3 capacitors with nano-Cr interlayer
(2007-03-26)
Ho, Chia-Cheng
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Chiou, Bi-Shiou
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Chang, Li-Chun
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電子工程學系及電子研究所
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Innovative Packaging Research Center
A multilayer Ba0.7Sr0.3TiO3/Cr/Ba0.7Sr0.3TiO3 (BST/Cr/BST) structure was sputtered sequentially onto Pt/Ti/SiO2/Si substrate. With the insertion of a 2 nm Cr interlayer, the temperature coefficient of capacitance of the BST/Cr/BST dielectric is about 69% lower than that of BST monolayer dielectric. The dielectric constant and dissipation factor as the function of Cr thickness are studied. X-ray diffraction patterns, the analysis results of energy dispersive spectroscopy, and the survey scan profiles of Auger electron spectroscopy reveal the formation of a TiO2 secondary phase after the multilayer is annealed at 800 degrees C in O-2 atmosphere. The insertion of nano-Cr interlayer improves the electrical properties of BST capacitors. (c) 2007 American Institute of Physics.
Thickness-dependent microstructures and electrical properties of CaCu3Ti4O12 films derived from sol-gel process
(2007-12-03)
Chang, Li-Chun
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Lee, Dai-Ying
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Ho, Chia-Cheng
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Chiou, Bi-Shiou
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電子工程學系及電子研究所
CaCu3Ti4O12 (CCTO) thin films with various thicknesses were prepared by a sol-gel multiple coating processes on Pt/Ti/SiO2/Si substrates. Microstructures and surface morphologies of CCTO thin films were analyzed by grazing incident X-ray diffractometer (GIXRD) and scanning electron microscope (SEM), respectively. The correlation between the thickness and electrical properties of CCTO films was investigated. The dielectric constants of CCTO films decreased with increasing film thickness (coating cycle). Both the dielectric constant of CCTO films and interlayer are calculated. Possible mechanisms are explored to explain the thickness dependence of the dielectric constant of CCTO films. (C) 2007 Elsevier B.V. All rights reserved.