Browsing by Author "Wu, Chi-Chang"

Now showing 1 - 19 of 19

A Novel Ion-Bombarded and Plasma-Passivated Charge Storage Layer for SONOS-Type Nonvolatile Memory
(2012-10-01)
Liu, Sheng-Hsien
;
Yang, Wen-Luh
;
Wu, Chi-Chang
;
Chao, Tien-Sheng
;
電子物理學系
A novel technique combination of ion bombardment (IB) and NH3 plasma treatment (PT) has been presented to yield a highly effective charge storage layer for Si/SiO2/Si3N4/SiO2/Si (SONOS)-type nonvolatile memory applications. The IB technique creates additional trap sites within the charge storage layer strikingly to enhance the charge trapping/detrapping efficiency of the storage layer, and the NH3 PT passivates shallow trap sites significantly to improve reliability characteristics. The distribution of trap sites corresponding with various energy levels is clearly described by discharge-based multipulse analysis. As compared with the control sample (without IB and NH3 PT), the ion-bombarded and NH3-plasma-passivatedmemory device has faster program/erase speeds and larger memory window. In addition, the competent reliability properties of the ion-bombarded and NH3-plasma-passivated memory, such as good endurance, long data retention, and acceptable disturbance, were also demonstrated in this letter.
A Robust Data Retention Characteristic of Sol-Gel-Derived Nanocrystal Memory by Hot-Hole Trapping
(2010-07-01)
Wu, Chi-Chang
;
Ko, Fu-Hsiang
;
Yang, Wen-Luh
;
You, Hsin-Chiang
;
Liu, Fu-Ken
A new sol-gel-derived Ti(x)Zr(y)Si(z)O nanocrystal (NC) memory with a high-performance data retention characteristic is demonstrated by the hot-hole-trapping method. Prior to rapid thermal annealing, the high-density NC layer is formed by depositing a well-mixed solution of titanium tetrachloride, silicon tetrachloride, and zirconium tetrachloride. The electrical properties of the sol-gel-derived NC memory are demonstrated in terms of memory window, charge retention, program speed, and endurance. The memory window of the NC memory from the novel hot-hole-trapping mechanism can be achieved up to 4.18 +/- 0.21 V, and long retention times obtained from extrapolation up to 10(6) s are observed as 8%, 13%, and 21% window narrowing under respective temperatures of 25 degrees C, 85 degrees C, and 125 degrees C. The good electrical performance is attributed to the contribution of the high density of isolated NCs and hole-trapped into the deep-trap energy level, so no significant lateral and vertical charge leakage occurs.
Effects of capping layers on the electrical characteristics of nickel silicided junctions
(2007-05-01)
Wu, Chi-Chang
;
Wu, Wen-Fa
;
Su, P. Y.
;
Chen, L. J.
;
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.
Facile sol-gel preparation of nanocrystal embedded thin film material for memory device
(2013-01-01)
Wu, Chi-Chang
;
Tsai, Yi-Jen
;
Liu, Pin-Lin
;
Yang, Wen-Luh
;
Ko, Fu-Hsiang
A promising charge trapping film with crystal embedded material is proposed for future electronic devices. Instead of conventional high-vacuum and expensive tool, this technique adopts very cheaper process of sol-gel spin-coating for fabrication of thin film material in the charge trapping flash memory (CTFM). The crystal from spinodal phase separation is observed for sol-gel thin film at 900 degrees C annealing, and is strongly related to the thickness of the spin-coated thin film. The morphology of the crystal from the ethanol solvent system is in the isolated form, while from 2-propanol solvent is in the interconnected structure. The sol-gel-derived CTFM from ethanol exhibits the better memory performance of retention times for <5 and <10 % charge loss at applied temperature of 25 and 85 degrees C, respectively. The ethanol system CTFM demonstrates a large memory window (similar to 10 V) and good reliability than 2-propanol (similar to 3 V) due to the existence of several isolated crystals in silicon dioxide film.
High-Performance Double-Layer Nickel Nanocrystal Memory by Ion Bombardment Technique
(2013-10-01)
Liu, Sheng-Hsien
;
Yang, Wen-Luh
;
Lin, Yu-Hsien
;
Wu, Chi-Chang
;
Chao, Tien-Sheng
A novel ion bombardment (IB) technique is presented to fabricate and embed double-layer (DL) Ni nanocrystal (NC) in silicon nitride for TaN/Al2O3/Si3N4/SiO2/Si nonvolatile memory applications. In contrast to other methods of forming DL metal NC, the IB technique is a relatively simple fabrication method and completely compatible with the current IC manufacturing technologies. Using the IB technique, a high-quality ultrathin interlayer between top and bottom layered NCs can be easily formed and controlled. Compared with the control sample, the IB-induced DL Ni NC memory exhibits superior performance in terms of faster program and erase (P/E) speeds, longer data retention, better endurance, negligible program disturbance, and great potential for a multilevel operation. In addition, the IB-induced DL Ni NC device also shows higher P/E efficiency as well as similar excellent reliability by comparison with other conventional DL metal NC memories due to the high-quality ultrathin interlayer.
High-Performance Polyimide-Based ReRAM for Nonvolatile Memory Application
(2013-01-01)
Liu, Sheng-Hsien
;
Yang, Wen-Luh
;
Wu, Chi-Chang
;
Chao, Tien-Sheng
;
Ye, Meng-Ru
In this letter, high-performance polyimide (PI)-based resistive random access memory (ReRAM) is presented by utilizing a new DAXIN-PI thin film as a resistance layer. The switching between high-and low-resistance states is triggered by the formation and dissociation of the charge transfer complex. As compared with the electrochemical-metallization-based ReRAM and the valence-change-based ReRAM, this DAXIN-PI ReRAM shows excellent performance, including large Ron/Roff ratio, superior endurance, low operation voltage, fast switching speed, needless of a forming process, and acceptable retention characteristics. Among them, large Ron/Roff ratio (> 10(5)) and superior endurance (> 10(5) cycles) can be simultaneously achieved, and the detailed reliability test for PI-based ReRAMs has been analyzed for the first time.
Improving electrical characteristics of Ta/Ta2O5/Ta capacitors using low-temperature inductively coupled N2O plasma annealing
(2007)
Tsai, Kou-Chiang
;
Wu, Wen-Fa
;
Chao, Chuen-Guang
;
Wu, Chi-Chang
;
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.
Ion-Bombarded and Plasma-Passivated Charge Storage Layer for SONOS-Type Nonvolatile Memory
(2014-09-01)
Liu, Sheng-Hsien
;
Wu, Chi-Chang
;
Yang, Wen-Luh
;
Lin, Yu-Hsien
;
Chao, Tien-Sheng
This paper examined the application of ion bombardment (IB) and NH3 plasma treatment (PT) techniques in fabricating a high-performance Si3N4 charge storage layer. The IB technique can be used for creating numerous additional trap sites in the storage layer to enhance charge trapping efficiency and also causes changes in trap centroid location. In addition, the effect of centroid location on operation efficiency and reliability was investigated. Using gate-sensing and channel-sensing analysis, the changes in centroid location were demonstrated. In addition, the energy-level distribution of trap sites was clearly delineated by performing discharge-based multipulse analysis. The NH3 PT technique can substantially passivate IB-induced shallow trap sites to increase data retention time. The influence of the NH3 PT time on the memory characteristics of an IB-induced Si3N4 sample was investigated. The optimal characteristics of an ion-bombarded and plasma-passivated Si3N4 storage layer are presented. Compared with the conventional Si3N4 storage layer, the optimal ion-bombarded and plasma-passivated Si3N4 sample exhibited higher operation efficiency and superior reliability.
Label-free biosensing of a gene mutation using a silicon nanowire field-effect transistor
(2009-12-15)
Wu, Chi-Chang
;
Ko, Fu-Hsiang
;
Yang, Yuh-Shyong
;
Hsia, Der-Ling
;
Lee, Bo-Syuan
We have developed a silicon nanowire field-effect transistor (NWFET) that allows deoxyribonucleic acid (DNA) biosensing. The nanowire (NW) was fabricated on a silicon-on-insulator wafer to provide effective ohmic contact. The NWFET sensor displayed n-channel depletion characteristics. To demonstrate the sensing capacity of the NWFET, we employed the BRAF(V599E) mutation gene, which correlates to the occurrence of cancers, as the target DNA sequence. The threshold voltage of the NWFET increased when the mutation gene was hybridized with the capture DNA strands on the nanowire, and decreased to the original level after de-hybridization of the gene. The shift in the drain current-gate voltage (ID-VG) curves revealed that the electrical signal had a logarithmic relationship with respect to the concentration of the mutation gene of up to six orders of magnitude, with the detection limit in the sub-femtomolar level. The detection results of mismatched DNA sequences, including one- and five-base-mismatched DNA strands, could be distinguished from complementary DNA gene by this sensor. The excellent electrical results obtained using this label-free NWFET sensor suggest that such devices might be potentially useful tools for biological research and oncogene screening. (C) 2009 Elsevier B.V. All rights reserved.
Label-free Detection of Prostate Specific Antigen Using a Silicon Nanobelt Field-effect Transistor
(2012-05-01)
Wu, Chi-Chang
;
Pan, Tung-Ming
;
Wu, Chung-Shu
;
Yen, Li-Chen
;
Chuang, Cheng-Keng
In this study, we proposed a silicon nanobelt field-effect transistor (FET) to detect prostate specific antigen (PSA). The nanobelt FET device displayed n-channel depletion characteristics. The immobilization of prostate specific antibody (anti-PSA) molecules was attached onto the nanobelt FET surface by using the aldehyde groups of glutaraldehyde linked to the amino groups of 3-aminopropyltriethoxysilane (APTES). The shift in the drain current vs time curves of a nanobelt FET biosensor revealed that the electrical signal had a logarithmic relationship with respect to the concentration of the PSA, and detection capability was estimated in the 5 pg/mL level. To enhance the sensitivity of a nanobelt FET biosensor, this biosensor was designed by inserting arginine molecules between glutaraldehyde and APTES. Therefore, the detection capability of the developed sensor was extended to 50 fg/mL. Also, the relationship between the current shift and the logarithm of PSA concentration was exhibited linearity in the range 50 fg/mL - 500 pg/mL. The excellent electrical results of this label-free PSA nanobelt FET biosensor suggested that such biosensor might be potentially useful tools for biological research and future prostate cancer screening.
Nanocrystallization and interfacial tension of sol-gel derived memory
(2008-03-24)
Wu, Chi-Chang
;
Tsai, Yi-Jen
;
Chu, Min-Ching
;
Yang, Shao-Ming
;
Ko, Fu-Hsiang
The formation of the nanocrystals (NCs) by using the sol-gel spin-coating method at various annealing temperatures had been studied. The film started to form the islands at 600 degrees C annealing, and finally transferred into NCs at 900 degrees C. A model was proposed to explain the transformation of thin film. The morphology of sol-gel thin film at 600 degrees C annealing was varied and had higher interfacial energy. The crystallized process at 900 degrees C annealing could minimize the energy. The retention for 900 degrees C annealed sample exhibited less than 30% charge loss after 10(6) s at 125 degrees C measurement. (c) 2008 American Institute of Physics.
Nanowire Field Effect Transistor With its Sub-picomolar Label-free Biosensing Capability Toward a Gene Mutation
(2010)
Wu, Chi-Chang
;
Ko, Fu-Hsiang
;
Su, Ting-Siang
;
Li, Bo-Syuan
;
Wu, Wen-Fa
We describe the efficiency of deoxyribonucleic acid (DNA) immobilization onto a nanowire (NW) after employing various surface cleaning methods. From surface tension measurements and fluorescence microscopy images of the silicon oxide surfaces, we determined that the effectiveness of surface cleaning using an acetone/ethanol mixture was similar to that of piranha solution (sulfuric acid/hydrogen peroxide). Thus, we employed surface cleaning with an acetone/ethanol mixture en route toward the fabrication of a series of label-free, back-gated, 60-nm nanowire field-effect transistor (NWFET) sensors for the detection of the BRAFV599E oncogene. We applied the NWFET sensor to the successful detection of the hybridization and dehybridization processes of the BRAFV599E mutation gene.
Novel coexisted sol-gel derived poly-Si-oxide-nitride-oxide-silicon type memory
(2007-11-01)
You, Hsin-Chiang
;
Wu, Chi-Chang
;
Ko, Fu-Hsiang
;
Lei, Tan-Fu
;
Yang, Wen-Luh
The authors use a very simple sol-gel spin coating method at 900 degrees C and 1 min rapid thermal annealing to fabricate three different poly-Si-oxide-nitride-oxide-silicon-type flash memories. The memory windows estimated from the curve of drain current versus applied gate voltage are 3, 3.3, and 4 V for (i) HfO2 thin film, (ii) hafnium silicate nanocrystal, and (iii) coexisted hafnium silicate and zirconium silicate nanocrystal memory, respectively. Together with the measurement from gate disturbance and drain disturbance on these fabricated devices, the coexisted nanocrystal devices exhibit better reliability than both the thin film type memory and single nanocrystal type memory. (C) 2007 American Vacuum Society.
Novel Ion Bombardment Technique for Doping Limited Cu Source in SiOx-Based Nonvolatile Switching Layer
(2013-11-01)
Liu, Sheng-Hsien
;
Yang, Wen-Luh
;
Lin, Yu-Hsien
;
Wu, Chi-Chang
;
Chao, Tien-Sheng
A novel ion bombardment (IB) technique is presented to dope a limited Cu source in an SiOx switching layer (SiOx:Cu SL) for nonvolatile memory applications. Compared with other Cu-doping methods, this IB technique has many benefits, including a local-doping effect, room-temperature process, and compatibility with current IC manufacturing technology, besteading the 1T-1R integration. Through transmission electron microscopy and energy dispersive spectrometer analyses, an IB-induced SiOx:Cu SL is confirmed. In contrast with the conventional Cu/SiOx-stacked sample, this IB-induced SiOx:Cu SL exhibits superior performance in terms of lower forming/RESET voltages, higher uniformity of SET/RESET voltages, and more stable high-temperature retention characteristics. Additionally, so far, this IB-induced TaN/SiOx:Cu/TaN device has shown the best switching endurance properties for the general SiOx-based Cu filament resistance random access memory.
Novel Sol-gel Derived SONOS-type Nanocrystal Memory
(2010)
Wu, Chi-Chang
;
You, Hsin-Chiang
;
Ko, Fu-Hsiang
;
Yang, Wen-Luh
;
材料科學與工程學系奈米科技碩博班
A nanocrystal (NC) memory by sol-gel spin-coating method was demonstrated. The high-density and isolated NC was formed by depositing a mixed solution of nickel tetrachloride, zirconium tetrachloride, silicon tetrachloride, and germanium tetrachloride with a post-rapid thermal annealing process. The electrical properties in terms of memory window, charge retention, program/erase speed, and endurance were demonstrated. The memory window of the NC memory can be up to 2.8 V: the retention times were extrapolated up to 10(6) sec for about 5% and 10% charge loss at 25 and 85 degrees C measurement, respectively. The voltage shift after 10(4) program/erase cycles is less than 1V. The good electrical performance was attributed to the effects of the high-density isolated NCs.
PREDICTIVE QUANTIZATION OF BIT LOADING FOR MIMO TIME-CORRELATED CHANNELS WITH LIMITED FEEDBACK
(2014-01-01)
Lin, Yuan-Pei
;
Wu, Chi-Chang
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
In this paper we consider variable-rate transmission for time-correlated MIMO (multi-input multi-output) channels with limited feedback. The number of bits loaded on each subchannel of the MIMO system is dynamically assigned according to the current channel condition and fed back to the transmitter. As the channel is time-correlated, so is bit loading. We propose to feedback bit loading using predictive coding, which is known to be a powerful technique for quantizing correlated signals. Assuming the channel is a first-order Gauss-Markov random process, we derive the optimal predictor for the bit loading to be coded. We show that the subchannels prediction errors are approximated Gaussian and thus can be quantized using quantizers designed for Gaussian random variables. Simulations demonstrate that the proposed predictive coding can achieve a very good approximation of the desired transmission rate with a very low feedback rate.
Stress-induced morphology and fine-line stability enhancement of NiSi on poly-SiGe with a buffer polycrystalline silicon interlayer
(2008-05-05)
Wu, Chi-Chang
;
Wu, Wen-Fa
;
Ko, Fu-Hsiang
;
You, Hsin-Chiang
;
Yang, Wen-Luh
The thermal and morphological stability of NiSi is enhanced by inserting a polycrystalline (poly-Si) buffer layer between the Ni and poly-SiGe films. NiSi films formed on poly-Si/poly-SiGe stack layers possessed continuous, smooth structures after annealing at 500-850 degrees C. Moreover, nickel germanosilicide [Ni(Si, Ge)] lines formed on the poly-SiGe exhibited a fine-line effect, i.e., the sheet resistance increased upon decreasing the linewidth, whereas the sheet resistance of NiSi lines formed on the poly-Si/poly-SiGe stack layers remained less than 5 Omega/square. A model for the stress-confined grain growth and recrystallization is proposed to explain the improved properties of the poly-Si-buffered film. (c) 2008 American Institute of Physics.
Surface Cleaning of the Nanowire Field-Effect Transistor for Gene Detection
(2011-12-01)
Wu, Chi-Chang
;
Liu, Fu-Ken
;
Lin, Ling-Hung
;
Pang, See-Tong
;
Chuang, Cheng-Keng
The efficiency of DNA immobilization by using various surface cleaning methods is studied in this work. The degree of surface cleaning is evaluated by the surface tension measurement to reveal the contribution from the polar and apolar terms. The observation from the fluorescent microscope images indicates the effectiveness of surface clean by the acetone and ethanol mixtures, as well as the sulphuric acid and hydrogen peroxide mixtures. We also fabricate a series of back-gated, 60-nm nanowired (NW) field-effect transistor (FET) sensors for mutation gene detection by following the developed acetone and ethanol mixtures. Electrical properties of the NWFET sensor demonstrate the n-channel depletion characteristics. The current of the sensor is reduced once the attachment of negative charge molecules. The single-stranded capture DNA is chemically immobilized onto the surface of silicon NWFET by three-step reactions. The sensor surface demonstrates the great performance of current shift after the suitable cleaning. The NWFET sensor is successfully applied to detect the BRAF(V599E) mutation genes from the hybridized processes. The sensing behaviour estimated from the electrical signal reaches the femtomolar level.
Ultra-fast and sensitive silicon nanobelt field-effect transistor for high-throughput screening of alpha-fetoprotein
(2018-03-01)
Manga, Yankuba B.
;
Ko, Fu-Hsiang
;
Yang, Yuh-Shyong
;
Hung, Jia-Yang
;
Yang, Wen-Luh
In this paper, we described a novel fabrication technique for Silicon nanobelt field-effect transistors (SiNB FETs) based on the Local Oxidation of Silicon (LOCOS) process widely utilized in the manufacturing of microelectronics components and explore it to screened alpha-fetoprotein (AFP). LOCOS process is used as it enables thorough compatibility with complementary metal oxide semiconductor (CMOS) technology. Thus, the need for expensive lithography tools to define the nanoscale pattern is avoided. The SiNB FETs emerges as a powerful biosensor for ultrasensitive, label-free for biological/chemical detection and direct electrical readout. The analytical sensing results of the fabricated SiNB FETs employed as a biomolecular sensor for the early, real-time, and label-free screening of AFP can be understood in term of the change in charge density at the silicon nanobelt surface after functionalization. It is observed that, by tuning the gate voltage, the electrical linearity response of the system towards AFP extends its concentration range from 3 ng/mL to 100 ng/mL, allowing the screening of hepatocellular carcinoma (HCC). These results indicate that the detection of AFP under our direct, label-free, and ultrasensitive biosensor in a microfluidic channel could be one of the promising state-of-the-art techniques applicable as an AFP detector in real samples. (C) 2017 Elsevier B.V. All rights reserved.