Browsing by Author "Wu, Wen-Fa"

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A Comprehensive Study of Ge1-xSix on Ge for the Ge nMOSFETs with Tensile Stress, Shallow Junctions and Reduced Leakage
(2009)
Luo, Guang-Li
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Huang, Shih-Chiang
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Chung, Cheng-Ting
;
Heh, Dawei
;
Chien, Chao-Hsin
For the first time, growth of high-quality Ge-rich Ge1-xSix (0 <= x <= 0.14) layers on Ge substrate was demonstrated. An effective suppression of the phosphorus diffusion in Ge1-xSix and a better thermal stability of the nickel germanide on Ge1-xSix were observed. A higher rectifying ratio with a reduced diode leakage current in n(+)-Ge1-xSix/p-Ge1-xSix is compared with n(+)-Ge/p-Ge. These results indicate that it is suitable for Ge1-xSix to be used as source/drain (S/D) to fabricate the uniaxial tensile-strained channel Ge nMOSFETs.
Diamond-shaped Ge and Ge0.9Si0.1 Gate-All-Around Nanowire FETs with Four {111} Facets by Dry Etch Technology
(2015)
Lee, Yao-Jen
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Hou, Fu-Ju
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Chuang, Shang-Shiun
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Hsueh, Fu-Kuo
;
Kao, Kuo-Hsing
We propose a feasible pathway to scale the Ge MOSFET technology by using a novel diamond-shaped Ge and Ge0.9Si0.1 gate-all-around (GAA) nanowire (NW) FETs with four {111} facets. The device fabrication requires only simple top-down dry etching and blanket Ge epitaxy techniques readily available in mass production. The proposed dry etching process involves three isotropic/anisotropic etching steps with different Cl-2/HBr ratios for forming the suspended diamond-shaped channel. Taking advantages of the GAA configuration, favorable carrier mobility of the {111} surface, nearly defect-free suspended channel, and improved dopant activation by incorporating Si, nFET and pFET with excellent performance have been demonstrated, including an I-on/I-off ratio exceeding 10(8), the highest ever reported for Ge-based pFETs.
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
;
Ho, Chia-Cheng
;
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 annealing treatment and nanomechanical properties for multilayer Si(0.8)Ge(0.2)-Si films
(2010-06-01)
He, Bo-Ching
;
Wen, Hua-Chiang
;
Lin, Meng-Hung
;
Lai, Yi-Shao
;
Wu, Wen-Fa
Multilayered silicon-germanium (SiGe) films consisting of alternating sublayers with different mechanical properties have been epitaxially deposited by an ultra-high vacuum chemical vapor deposition (UHV/CVD) system. We report engineering of the mechanical properties of SiGe multilayer films by a commercial nanoindenter. From annealing treatment, it consists of an ex situ thermal treatments in furnace (600 degrees C) and rapid thermal annealing (800 degrees C) system. Subsequent roughness and microstructure of SiGe multilayer films were characterized by means of atomic force microscope (AFM) and transmission electron microscopy (TEM). The annealing treatment not only produced misfit dislocations as a significant role in the critical pile-up event but also promoted hardness. The hardness of the films increased slightly and then gradually achieved a maximum value (from 12.6 +/- 0 4 GPa to 14.2 +/- 0.7 GPa) with increasing annealing temperature. This may be due to the relaxation effect from thermal annealing and is potential to provide the reliability behaviours to design periodical SiGe multilayer structure in further. (C) 2010 Published by Elsevier Ltd
Effect of Nitrogen Plasma Treatment on Electrical Characteristics for Pd Nanocrystals in Nonvolatile Memory
(2010-08-01)
Kang, Tsung-Kuei
;
Liao, Ta-Chuan
;
Lin, Cheng-Li
;
Wu, Wen-Fa
;
電子工程學系及電子研究所
Pd nanocrystals (NCs) are successfully embedded in a TaN/SiO(2)/HfAlO/Si structure The initial memory window increases at a higher rate with increasing fabrication temperature of Pd NCs compared with the linear variation of Pd NC density, which is related to the thermally induced neutral traps in the HfAlO film around Pd NCs After manufacturing a TaN/SiO(2)/Pd NCs/HfAlO/Si/Al structure, the subsequent N(2) plasma treatment is conducted at 300 degrees C for 3 min The number of leakage current paths in the SiO(2) blocking layer adjacent to TaN is clearly reduced, but that of leakage current paths in SiO(2)/HfAlO around Pd NCs is slightly increased owing to the thermal stress The thermally induced neutral traps in the HfAlO film around the Pd NCs can be passivated by nitrogen atoms, which leads to the improvement of the final memory window for the Pd NC samples fabricated at 600-700 degrees C However, the intrinsic traps in the HfAlO film play an important role in memory characteristic and the final memory window is reduced by thermal densification for the Pd NC samples fabricated at 500 degrees C (C) 2010 The Japan Society of Applied Physics
Effect of repetition nanoindentation of GaN epilayers on a-axis sapphire substrates
(2011-05-01)
Lin, Meng-Hung
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Wen, Hua-Chiang
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Chang, Zue-Chin
;
Wu, Shyh-Chi
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Wu, Wen-Fa
In this work, gallium nitride (GaN) epilayers were deposited on a-axis sapphire substrate by means of metal organic chemical vapor deposition (MOCVD). Berkovich nanoindentation was used to explore the repetition pressure-induced impairment of the GaN film. The observation of load-displacement vs stress-strain curves concludes that basal slip is implicated in the deformation on the A plane GaN. The increase in the hardness (H) and elasticmodulus (E) was determined from cyclic nanoindentation, and resulted in a crack due to the formation of incipient slip bands and/or the to-and-fro motion of mobile dislocation. It is indicated that the generation of individual dislocation and residual deformation of the GaN films are showed by CL mapping analysis. From the morphological studies, it is revealed that the crack was found by means of atomic force microscope (AFM) technique at nine loading/reloading cycles even after the indentation beyond the critical depth on the residual indentation impression. Copyright (C) 2010 John Wiley & Sons, Ltd.
Effect of strain relaxation of oxidation-treated SiGe epitaxial thin films and its nanomechanical characteristics
(2010-03-01)
He, Bo-Ching
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Wen, Hua-Chiang
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Chinag, Tun-Yuan
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Chang, Zue-Chin
;
Lian, Derming
In this study, we examined the effect of high-temperature oxidation treatment on the SiGe epitaxial thin films deposited on Si substrates. The X-ray diffraction (XRD), atomic force microscopy (AFM), and nanoindentation techniques were employed to investigate the crystallographic structure, surface roughness, and hardness (H) of the SiGe thin films, respectively. The high-temperature oxidation treatment led to Ge pileup at the surface of the SiGe thin films. In addition, strain relaxation occurred through the propagation of misfit dislocations and could be observed through the cross-hatch pattern (800-900 degrees C) and SiGe islands (1000 degrees C) at the surface of the SiGe thin films. Subsequent hardness (H) measurement on the SiGe thin films by continuous penetration depth method indicated that the phenomenon of Ge pileup caused a slightly reduced H (below 50 nm penetration depth), while relaxation-induced defects caused an enhanced H (above 50 nm penetration depth). This reveals the influence of composition and defects on the structure strength of high-temperature oxidation-treated SiGe thin films. (C) 2009 Elsevier B.V. All rights reserved.
Effects of capping layers on the electrical characteristics of nickel silicided junctions
(2007-05-01)
Wu, Chi-Chang
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Wu, Wen-Fa
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Su, P. Y.
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Chen, L. J.
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Ko, Fu-Hsiang
In this paper, effects of capping layers on formation and electrical properties of Ni-silicided junctions have been investigated. Nickel silicide films using the Ti or TiN-capped layer process are used to compare to those by the uncapped process. The uncapped (Ni single layer) and TiN-capped samples are shown to exhibit better thermal stability than the Ti-capped samples. For the silicided junctions, samples using Ti capping layer processes exhibit larger leakage current densities. A high-resistivity NiTiSi, compound layer is formed on the surface during silicidation for the Ti-capped sample, while the uncapped and TiN-capped samples are not. In addition, it is found that the thickness of NiSi layer, as well as the Ni,TiySi, layer, increases with increasing the Ti capping layer thickness. The formation of Ni,TiySi, layer not only increases the contact resistance, but also deepens the silicide thickness. (c) 2007 Elsevier B.V. All rights reserved.
Evaluating nanotribological behavior of annealing Si(0.8)Ge(0.2)/Si films
(2011-12-01)
Wu, Ming-Jhang
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Wen, Hua-Chiang
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Wu, Shyh-Chi
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Yang, Ping-Feng
;
Lai, Yi-Shao
In this study, the SiGe epilayers were created on silicon substrate by using ultra-high vacuum chemical vapor deposition (UHV/CVD) and followed by annealing procedures. The frictional behaviors of SiGe epilayers were subjected to nanoscratch techniques under a ramping load. Damage caused by scratching was examined by atomic force microscopy (AFM); the results showed that the pile-up phenomena were significant on both sides of the scratch in the case of SiGe epilayers, suggesting that the dynamic deformation behavior was dominated by cracking as ploughing occurred during scratching. In addition, the SiGe epilayers films with different annealed conditions exhibited the decrease in coefficient of friction (COF), indicating the higher shear resistance exist in annealed SiGe epilayers, which probably affect the film uniformity and device yield under IC process integration. (C) 2011 Elsevier Ltd. All rights reserved.
Evaluating nanotribological behavior of annealing Si0.8Ge0.2/Si films
(2011-12-01)
Wu, Ming-Jhang
;
Wen, Hua-Chiang
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Wu, Shyh-Chi
;
Yang, Ping-Feng
;
Lai, Yi-Shao
In this study, the SiGe epilayers were created on silicon substrate by using ultra-high vacuum chemical vapor deposition (UHV/CVD) and followed by annealing procedures. The frictional behaviors of SiGe epilayers were subjected to nanoscratch techniques under a ramping load. Damage caused by scratching was examined by atomic force microscopy (AFM); the results showed that the pile-up phenomena were significant on both sides of the scratch in the case of SiGe epilayers, suggesting that the dynamic deformation behavior was dominated by cracking as ploughing occurred during scratching. In addition, the SiGe epilayers films with different annealed conditions exhibited the decrease in coefficient of friction (COF), indicating the higher shear resistance exist in annealed SiGe epilayers, which probably affect the film uniformity and device yield under IC process integration. (C) 2011 Elsevier Ltd. All rights reserved.
Evaluating the abrasive wear of Zn(1-x)Mn(x)O heteroepitaxial layers using a nanoscratch technique
(2010-08-01)
Chang, Yu-Ming
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Wen, Hua-Chiang
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Yang, Chu-Shou
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Lian, Derming
;
Tsai, Chien-Huang
In this study, we used nanoscratch techniques under a ramping load to evaluate the abrasive wear of Zn(1-x)Mn(x)O epilayers (0 <= x <= 0.16) grown through molecular beam epitaxy (MBE) on sapphire substrates. We analyzed the surface roughness and damage using atomic force microscopy (AFM) and nano-indenter techniques. The scratched surfaces of the Zn(1-x)Mn(x)O epilayers were significantly different for the various Mn compositions. AFM imaging of the Zn(1-x)Mn(x)O films revealed that pileup phenomena were important on both sides of each scratch. During the scratching process, we found that cracking dominated in the case of Zn(1-x)Mn(x)O films while ploughing; also we observed lower values of the coefficient of friction and shallower penetration depths for the films upon increasing the Mn content (x) from 0 to 0.16, suggesting that higher Mn contents provided the Zn(1-x)Mn(x)O epilayers with higher shear resistances, enhanced by the presence of MnO bonds. (C) 2010 Elsevier Ltd. All rights reserved.
Evaluating the abrasive wear of Zn1-xMnxO heteroepitaxial layers using a nanoscratch technique
(2010-08-01)
Chang, Yu-Ming
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Wen, Hua-Chiang
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Yang, Chu-Shou
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Lian, Derming
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Tsai, Chien-Huang
In this study, we used nanoscratch techniques under a ramping load to evaluate the abrasive wear of Zn1-xMnxO epilayers (0 <= x <= 0.16) grown through molecular beam epitaxy (MBE) on sapphire substrates. We analyzed the surface roughness and damage using atomic force microscopy (AFM) and nano-indenter techniques. The scratched surfaces of the Zn1-xMnxO epilayers were significantly different for the various Mn compositions. AFM imaging of the Zn1-xMnxO films revealed that pileup phenomena were important on both sides of each scratch. During the scratching process, we found that cracking dominated in the case of Zn1-xMnxO films while ploughing; also we observed lower values of the coefficient of friction and shallower penetration depths for the films upon increasing the Mn content (x) from 0 to 0.16, suggesting that higher Mn contents provided the Zn1-xMnxO epilayers with higher shear resistances, enhanced by the presence of MnO bonds. (C) 2010 Elsevier Ltd. All rights reserved.
Evaluation of the nanoindentation behaviors of SiGe epitaxial layer on Si substrate
(2010-01-01)
He, Bo-Ching
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Cheng, Chun-Hu
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Wen, Hua-Chiang
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Lai, Yi-Shao
;
Yang, Ping-Feng
In this paper, ultra-high vacuum chemical vapor deposition (UHV/CVD) was employed to synthesize silicon-germanium (SiGe), and sequence to endure annealing treatment. Morphological characterization, roughness, and microstructural morphology were observed by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The elements distribution, crystallographic, and nanomechanical behavior were carried out using energy-dispersive Xray spectroscopy (EDS) mapping technique, X-ray diffraction (XRD), and nanoindentation technique. The annealing treated SiGe leads to the 2D germanium segregation on the surface. The phenomenon is interpreted in terms of dislocation-induced structural changes in annealing treatment, Thus, the dislocation propagation in the microstructure was observed. Subsequently hardness and elastic modulus were increased because of a comparatively unstable microstructure after annealing treatment. (C) 2009 Elsevier Ltd. All rights reserved.
High Performance Poly Si Junctionless Transistors with Sub-5nm Conformally Doped Layers by Molecular Monolayer Doping and Microwave Incorporating CO2 Laser Annealing for 3D Stacked ICs Applications
(2015)
Lee, Yao-Jen
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Cho, Ta-Chun
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Sung, Po-Jung
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Kao, Kuo-Hsing
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Hsueh, Fu-Kuo
A junctionless (JL) fin thin film transistor (FinTFT) with a novel shell doping profile (SDP) formed by a damage-free conformal molecular monolayer doping (MLD) method and a combination of microwave annealing (MWA) and CO2 laser spike annealing (COLSA) is demonstrated and studied. MWA drives in and partially activates the MLD dopants; the resultant SDP features an ultra-shallow depth (< 5nm) and an abrupt steepness (< 0.8 nm/dec). The dopant activation of the devices experienced MLD and MWA is further enhanced by the nonmelting COLSA without dopant diffusion, and which can also avoid fin deformation and recover surface defects left by fin patterning. Thanks to the enhanced dopant activation by COLSA, the SDP-FinTFTs overall exhibit better performance than the SDP-FinTFTs without COLSA and the conventional implanted (imp) FinTFTs in terms of subthreshold swing (S.S.), on-currents (I-on by 160% compared to the SDP-FinTFTs without COLSA) and on/off current ratio (I-on/I-off > 10(7)) for 3D stacked ICs applications. Our results reveal the potential of the proposed SDP formed by MLD, MWA and COLSA enabling a JLFinTFT showing excellent performance.
Improved characteristics for Pd nanocrystal memory with stacked HfAlO-SiO(2) tunnel layer
(2011-07-01)
Kang, Tsung-Kuei
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Liu, Han-Wen
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Wang, Fang-Hsing
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Lin, Cheng-Li
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Liao, Ta-Chuan
Stacked HfAlO-SiO(2) tunnel layers are designed for Pd nanocrystal nonvolatile memories. For the sample with 1.5 nm-HfAlO/3.5 nm-SiO(2) tunnel layer, a smaller initial memory window is obtained compared to the sample with 3.5 nm-HfAlO/1.5 nm-SiO(2) tunnel layer. Owing to the thermally induced traps in HfAlO-SiO(2) films are located at a farther distance from the Si substrate and more effective blocking of charge leakage by asymmetric tunnel barrier, a larger final memory window and better retention characteristic can be obtained for Al/blocking oxide SiO(2)/Pd NC5/1.5 nm-HfAlO/3.5 nm-SiO(2)/Si structure. A N(2) plasma treatment can further improve the memory characteristics. Better memory characteristics can be obtained for Pd-nanocrystal-based nonvolatile memory with an adequate thickness ratio of HfAlO to SiO(2). (C) 2011 Elsevier Ltd. All rights reserved.
Improved characteristics for Pd nanocrystal memory with stacked HfAlO-SiO2 tunnel layer
(2011-07-01)
Kang, Tsung-Kuei
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Liu, Han-Wen
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Wang, Fang-Hsing
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Lin, Cheng-Li
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Liao, Ta-Chuan
Stacked HfAlO-SiO2 tunnel layers are designed for Pd nanocrystal nonvolatile memories. For the sample with 1.5 nm-HfAlO/3.5 nm-SiO2 tunnel layer, a smaller initial memory window is obtained compared to the sample with 3.5 nm-HfAlO/1.5 nm-SiO2 tunnel layer. Owing to the thermally induced traps in HfAlO-SiO2 films are located at a farther distance from the Si substrate and more effective blocking of charge leakage by asymmetric tunnel barrier, a larger final memory window and better retention characteristic can be obtained for Al/blocking oxide SiO2/Pd NC5/1.5 nm-HfAlO/3.5 nm-SiO2/Si structure. A N-2 plasma treatment can further improve the memory characteristics. Better memory characteristics can be obtained for Pd-nanocrystal-based nonvolatile memory with an adequate thickness ratio of HfAlO to SiO2. (C) 2011 Elsevier Ltd. All rights reserved.
Improving electrical characteristics of Ta/Ta2O5/Ta capacitors using low-temperature inductively coupled N2O plasma annealing
(2007)
Tsai, Kou-Chiang
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Wu, Wen-Fa
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Chao, Chuen-Guang
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Wu, Chi-Chang
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材料科學與工程學系
The electrical characteristics of Ta/Ta2O5/Ta capacitors are improved by treatments with inductively coupled N2O plasma. A low-temperature (250 degrees C) and short (5 min) process was used to reduce the leakage current and improve the reliability. A low leakage current density (4.0x10(-10) A/cm(2) under 1 MV/cm), high breakdown field (4.2 MV/cm at 10(-6) A/cm(2)), and lifetime of over 10 years at 1.61 MV/cm is obtained for the Ta/Ta2O5/Ta capacitor with the inductively coupled N2O plasma treatment. The conduction mechanism of the leakage current in the Ta/Ta2O5/Ta capacitor is discussed using current-voltage analyses and shows that the leakage current of the Ta/Ta2O5/Ta capacitor is dominated by Schottky emission. N2O plasma treatment can effectively reduce oxygen vacancies and the surface roughness of the Ta2O5 film, inhibiting the conduction of the leakage current. (c) 2007 The Electrochemical Study.
Improving electrical properties and thermal stability of (Ba,Sr)TiO3 thin films on Cu(Mg) bottom electrodes
(2006-06-01)
Tsai, Kou-Chiang
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Wu, Wen-Fa
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Chao, Chuen-Guang
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Lee, Jain-Tsai
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Shen, Shih-Wen
Cu(Mg) alloy films have replaced pure Cu as bottom electrodes for (Ba,Sr)TiO3 (BST) capacitors used in high-frequency devices. A combined BST/Cu(Mg) structure reduced the leakage current density to 3.0 x 10(-8) A/cm(2) at 1 MV/cm, and increased the breakdown field from 0.4 to 2.4 MV/cm at 10(-6) A/cm(2), from the corresponding values of the BST/Cu structure. High-quality characteristics probably follow the formation of a self-aligned MgO layer following the deposition of a Cu(Mg) alloy by annealing in an oxygen ambient, yielding an electrode with an excellent diffusion barrier and electrical characteristics, which is therefore effective in a BST thin-film capacitor. Additionally, the bias temperature stress and time-dependent dielectric breakdown in ambient nitrogen at an electric field of up to 2 V at temperatures between 100 and 200 degrees C were considered to accelerate Cu+ ion drift.
Induced NH2 bonding of carbon nanotubes using NH3 plasma-enhanced chemical vapor deposition
(2012-04-01)
Chiou, Ai-Huei
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Chang, Yu-Ming
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Wu, Wen-Fa
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Chou, Chang-Ping
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Hsu, Chun-Yao
Plasma-enhanced chemical vapor deposition was used to modify the multiwall carbon nanotubes (MWCNTs) using ammonia (NH3) plasma. For various durations of NH3 plasma treatment, a scanning electron microscope, X-ray, Raman spectroscopy and contact angle measurement were used to ascertain several characteristics of the MWCNTs. The experimental results show that: (1) the length of the MWCNTs is reduced, if the duration of the plasma treatment is increased; (2) the NH3 plasma treatment can incorporate amine (NH2-) or amino (NH-) functional groups onto the MWCNT surface; (3) the plasma treated carbon nanotubes become more hydrophilic.
Influence of bias-temperature stressing on the electrical characteristics of SiOC : H film with Cu/TaN/Ta-gated capacitor
(2006-07-01)
Tsai, Kou-Chiang
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Wu, Wen-Fa
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Chao, Chuen-Guang
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材料科學與工程學系
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Department of Materials Science and Engineering
Experiments on bias-temperature stressing, capacitance-voltage measurements, current-voltage characteristics, and time-dependent dielectric breakdown were performed to evaluate the reliability of Cu and low-k SiOC:H integration. A high leakage current of similar to 8 X 10(-10) to 2 X 10(-8) A/cm(2) at 1 MV/cm in SiOC:H dielectrics in a Cu-gated capacitor, and a lower 2 X 10(-10) to 5 X 10(-10) A/cm(2) at 1 MV/cm in a Cu/TaN/Ta-gated capacitor, were observed at evaluated temperatures. The drift mobility of the Cu ions in the Cu/TaN/Ta-gated capacitor was lower than that in a Cu-gated capacitor. A physical model was developed to explain the observed kinetics of Cu+ ions that drift in Cu-gated and Cu/TaN/Ta-gated capacitors. The electric field in the Cu-gated MIS capacitor in the cathode region is believed to be increased by the accumulation of positive Cu+ ions, which determines the breakdown acceleration. Good Cu, ions drift barrier layers are required as reliable interconnects using thin TaN and Ta layers. Additionally, Schottky emission dominates at low electric fields, E < 1.25 MV/cm, and Poole-Frenkel emission dominates at high fields, E > 1.5 MV/cm.