Browsing by Author "Chiu, HT"

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A comparative study of CVD TiN and CVD TaN diffusion barriers for copper interconnection
(1995)
Sun, SC
;
Tsai, MH
;
Chiu, HT
;
Chuang, SH
;
Tsai, CE
A heuristic approach for detecting RNA H-type pseudoknots
(2005-09-01)
Huang, CH
;
Lu, CL
;
Chiu, HT
;
生物科技學系
;
Department of Biological Science and Technology
Motivation: RNA H-type pseudoknots are ubiquitous pseudoknots that are found in almost all classes of RNA and thought to play very important roles in a variety of biological processes. Detection of these RNA H-type pseudoknots can improve our understanding of RNA structures and their associated functions. However, the currently existing programs for detecting such RNA H-type pseudoknots are still time consuming and sometimes even ineffective. Therefore, efficient and effective tools for detecting the RNA H-type pseudoknots are needed. Results: In this paper, we have adopted a heuristic approach to develop a novel tool, called HPknotter, for efficiently and accurately detecting H-type pseudoknots in an RNA sequence. In addition, we have demonstrated the applicability and effectiveness of HPknotter by testing on some sequences with known H-type pseudoknots. Our approach can be easily extended and applied to other classes of more general pseudoknots.
Adsorption and decomposition studies of t-butylamine, diethylamine, and methylethylamine on Si(100)-(2 x 1)
(2004-02-05)
Wu, JB
;
Yang, YW
;
Lin, YF
;
Chiu, HT
;
應用化學系
We have studied chemisorption and thermal decomposition of tert-butylamine (TBA), diethylamine (DEA), and methylethylamine (MEA) on Si(100)-(2 x 1) with synchrotron-based X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Adsorption at cryogenic temperature leads to molecularly intact chemisorption (dative-bonding via the nitrogen lone pair) and dissociative chemisorption via N-H scission, producing distinct N 1s peaks at binding energies of 401.1 and 398.2 eV, respectively. The corresponding change for C 1s core level is also significant, and a 0.9 eV shift toward lower binding energy is found for DEA, suggesting a high degree of charge redistribution between two adsorption configurations. Upon warming to room temperature, the adsorbed amines almost completely transform into dissociative chemisorbed forms. Thermal decomposition of TBA at elevated temperatures produces desorption species of isobutylene via gamma-H elimination, hydrogen cyanide, and H-2. In comparison, DEA and MEA decompose thermally to desorb imine via P-H elimination, ethylene via beta-H elimination, hydrogen cyanide, and H2. Eventually, silicon nitride and silicon carbide are formed. Distinct decomposition pathways lead to a C/N ratio variation among the products, with TBA yielding the lowest C/N ratio.
Applications of semiconductor nanoparticles in electron transfer, energy transfer and metal ion recognition.
(2004-08-22)
Chou, YH
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Chiu, HT
;
Chen, CY
;
Cheng, CT
;
Chou, PT
Carbon nanotubes as affinity probes for peptides and proteins in MALDI MS analysis
(2004-11-01)
Chen, WY
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Wang, LS
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Chiu, HT
;
Chen, YC
;
Lee, CY
Recently, carbon nanotubes (CNTs) have been reported to be an effective MALDI matrix for small molecules Anal. Chem 2003, 75, 6191). In a somewhat related study, we have employed CNTs produced by using NaH-treated anodic aluminum oxide (Na@AAO) as a reactive template as the assisting matrix for MALDI analysis upon the addition of high concentrations of citrate buffer. Our results indicate that the mass range can be extended to ca. 12,000 Da and that alkali metal adducts of analytes are effectively reduced. Furthermore, we have employed citric acid-treated CNTs as affinity probes to selectively concentrate traces of analytes from aqueous solutions. High concentrations of salts and surfactants in the sample solutions are also tolerated. This approach is very suitable for the MALDI analysis of small proteins, peptides, and protein enzymatic digest products. (J Am Soc Mass Spectrom 2004, 15, 1629-1635) (C) 2004 American Society for Mass Spectrometry.
Chemical vapor deposition of tantalum carbide and carbonitride thin films from Me3CE=Ta(CH2CMe3)(3) (E = CH, N)
(2003)
Chang, YH
;
Wu, JB
;
Chang, PJ
;
Chiu, HT
;
應用化學系
Chemical vapor deposition (CVD) of thin films employing Me3CCH=Ta(CH2CMe3)(3) and Me3CN=Ta(CH2CMe3)(3) as the precursors has been carried out. TaC and TaCN films were deposited at relatively low temperatures (623-923 K). In comparison, using Me3CN=Ta(CH2CMe3)(3), the Ta=N bond did not undergo cleavage during the reaction and the N atom was incorporated into the film as nitride. The volatile components evolved were collected and examined by GC-MS, FT-IR, H-1 and C-13 NMR spectroscopy. Possible decomposition pathways of the tantalum complexes are proposed to rationalize the observation.
Chemical vapor deposition of the hafnium oxynitride for use as HIGH-K materials in microelectronic devices.
(2004-08-22)
Chuang, SH
;
Chou, YH
;
Chiu, HT
;
應用化學系
;
Department of Applied Chemistry
Comparison of the diffusion barrier properties of chemical-vapor-deposited TaN and sputtered TaN between Cu and Si
(1996-05-01)
Tsai, MH
;
Sun, SC
;
Tsai, CE
;
Chuang, SH
;
Chiu, HT
This work investigated the barrier properties of metalorganic chemical-vapor-deposited (CVD) tantalum nitride (TaN) and physical-vapor-deposited (PVD) TaN between Cu and Si. The CVD TaN film had a preferred orientation (200) with a grain size of around 60 nm, while the PVD TaN had a (111) preferred orientation with a grain size of around 20 nm, as determined by transmission electron microscopy (TEM) and x-ray diffraction (XRD) analyses. Degradation study of the Cu/TaN/Si contact system was also performed by sheet resistance measurement, scanning electron microscopy (SEM), XRD, secondary ion mass spectroscopy (SIMS), and shallow junction diodes. These results indicated that the PVD TaN film can act as a better diffusion barrier than the CVD TaN film. The higher thermal stability of PVD TaN than CVD TaN can be accounted by their difference in microstructures. The failure mechanisms of both CVD TaN and PVD TaN films as diffusion barriers between Cu and Si were also discussed. (C) 1996 American Institute of Physics.
Comparison of the diffusion barrier properties of chemical-vapor-deposited TaN and sputtered TaN between Cu and Si
(1996-05-01)
Tsai, MH
;
Sun, SC
;
Tsai, CE
;
Chuang, SH
;
Chiu, HT
This work investigated the barrier properties of metalorganic chemical-vapor-deposited (CVD) tantalum nitride (TaN) and physical-vapor-deposited (PVD) TaN between Cu and Si. The CVD TaN film had a preferred orientation (200) with a grain size of around 60 nm, while the PVD TaN had a (111) preferred orientation with a grain size of around 20 nm, as determined by transmission electron microscopy (TEM) and x-ray diffraction (XRD) analyses. Degradation study of the Cu/TaN/Si contact system was also performed by sheet resistance measurement, scanning electron microscopy (SEM), XRD, secondary ion mass spectroscopy (SIMS), and shallow junction diodes. These results indicated that the PVD TaN film can act as a better diffusion barrier than the CVD TaN film. The higher thermal stability of PVD TaN than CVD TaN can be accounted by their difference in microstructures. The failure mechanisms of both CVD TaN and PVD TaN films as diffusion barriers between Cu and Si were also discussed. (C) 1996 American Institute of Physics.
Convergent electron beam induced growth of copper nanostructures: Evidence of the importance of a soft template
(2004-01-20)
Yen, MY
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Chiu, CW
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Chen, FR
;
Kai, JJ
;
Lee, CY
In a transmission electron microscope, CuCl particles were irradiated by a convergent electron beam (CEB, 200 kV, 200 pA/cm(2), beam diameter of ca. 1-2 mum) to induce growth of copper nanostructures. Upon CEB irradiation, Cu nanoparticles (5-20 nm in diameter) were formed from commercial CuCl. Using synthesized CuCl encapsulated in permethylpolysilane, growth of polycrystalline copper nanowires (50-200 nm in diameter and up to 30 mum in length) was observed. Evolution of Cu nanoparticles from the synthesized CuCl was observed from the positions with apparent incomplete encapsulation. The effect of polymer encapsulation, acting as a soft template, is shown to be important to influence the nanostructure growth. The observation supports the vapor-solid reaction growth model.
Correlation between N 1s XPS binding energy and bond distance in metal amido, imido, and nitrido complexes
(2003-07-28)
Wu, JB
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Lin, YF
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Wang, JL
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Chang, PJ
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Tasi, CP
Synchrotron-based X-ray photoelectron spectroscopy is used to measure N 1s binding energies of several metal amido, imido, and nitrido complexes of group 5 and 6 metals. The N 1s binding energy decreases as the formal M-N bond order increases. A simple correlation between the contraction of the M-N bond and the lowering of binding energy is also observed. This correlation supports a notion that the bonding character of a linear metal-imido linkage resembles that of a metal-nitrido linkage closely.
Elongation of arrays of amorphous carbon tubes
(2005-10-01)
Wang, LS
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Wang, CH
;
Peng, CW
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Lee, CY
;
Chiu, HT
Formation of mononuclear nitrido complexes of chromium(VI) and molybdenum(VI); Syntheses and X-ray crystal structures of N Cr(OBu(t))(3) and N Mo(OSiMe(3))(3)(py)
(1996-01-21)
Chiu, HT
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Chen, YP
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Chuang, SH
;
Jen, JS
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Lee, GH
Mononuclear nitrido complexes of Cr and Mo, N=Cr(OBu(t))(3) and N=Mo(OSiMe(3))(3)(py), are synthesized; the chromium complex has an idealized C-3v symmetry while the molybdenum complex has a distorted square-pyramidal geometry with the nitrido ligand at apical position; the N-Cr distance is 1.538(5) Angstrom while the average N-Mo distance is 1.627 Angstrom.
Growth of CaF2/a-C core/shell nanowires.
(2005-03-13)
Huang, CH
;
Chang, YH
;
Lee, CY
;
Chiu, HT
;
應用化學系
In situ generation of the silica shell layer - Key factor to the simple high yield synthesis of silver nanowires
(2003-08-20)
Hsia, CH
;
Yen, MY
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Lin, CC
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Chiu, HT
;
Lee, CY
Kinetic and mechanistic studies of the chemical vapor deposition of tungsten nitride from bis(tertbutylimido)bis(tertbutylamido)tungsten
(2001-05-03)
Crane, EL
;
Chiu, HT
;
Nuzzo, RG
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應用化學系
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Department of Applied Chemistry
The chemical vapor deposition (CVD) of tungsten nitride from a single source reagent, bis(tertbutylimido)-bis(tertbutylamido)tungsten ((t-BuN)(2)W(NKBut)(2)), is examined with particular focus placed on the mechanisms and energetics involved in the activation and thermal decomposition of this CVD precursor. The main reactions that take place are (1) activated adsorption of the precursor, (2) hydrogen addition/exchange, leading to the evolution of tert-butylamine, (3) ligand activation via both gamma -hydride activation and B-methyl elimination processes, and (4) Ligand decomposition via C-N bond rupture. The activation energies fbr each of these processes were examined and found to be similar to 30 kcal/mol for the process(es) leading to the evolution of tert-butylamine and similar to 40 kcal/mol for the various reactions which lead to the fragmentation of the precursor ligands (pathways which appear to involve both C-H and C-C bond activation as well as the rupture of the ligand C-N bonds). The growth surface of the deposited film contained extensive quantities of carbon in addition to tungsten and nitrogen. The data also suggest that the growth in UHV does not yield a stable bulk nitride phase. Rather, it was found that the nitrogen appears to be present at levels consistent with the formation of a solid solution and that annealing to 700 K results in the loss of the nitrogen from the bulk film (as N-2).
Low-temperature solution route to molybdenum nitride
(1998-12-01)
Chiu, HT
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Chuang, SH
;
Lee, GH
;
Peng, SM
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應用化學系
Low-temperature solution route to molybdenum nitride
(1998-12-01)
Chiu, HT
;
Chuang, SH
;
Lee, GH
;
Peng, SM
;
應用化學系
Low-temperature synthesis of transition metal nanoparticles from metal complexes and organopolysilane oligomers
(2002-10-01)
Chang, YH
;
Wang, HW
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Chiu, CW
;
Cheng, DS
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Yen, MY
Mo, W, and Cu nanoparticles (5-50 nm) are synthesized from reactions employing a metal complex, such as MoO2Cl2(DME), MoCl5, WCl6, ((CuOBu)-Bu-t)(4), or CuCl2, and a organopolysilane oligomer Si(SiMe3)(4) or (SiMe2)(6) either in a hexane solution (343 K) or in a sealed tube (473-673 K). Oxo- and chlorophilicities of the silyl groups provide for an energetically favored reaction route to reduce the metal complexes. The reaction byproducts are removed easily either by evaporation or dissolution into hydrocarbon solvents. It is proposed that the homogeneous mixing of the reactants in vapor and solution phases allows the association and growth of molecules into small clusters, then into nanosized metal particles.
Metal-organic chemical vapor deposition of tantalum nitride barrier layers for ULSI applications
(1995-12-01)
Tsai, MH
;
Sun, SC
;
Lee, CP
;
Chiu, HT
;
Tsai, CE
Low-resistivity tantalum nitride (TaN) films were deposited by low-pressure metal-organic chemical vapor deposition (MOCVD) using a new precursor tertbutylimidotrisdiethyl amidotantalum. The surface morphology and the step coverage of TaN films were characterized by scanning electron microscopy. The film deposited at 450 degrees C had nearly 100% step coverage and the step coverage decreased to 25% for the films deposited at 650 degrees C, The carbon and oxygen concentrations are about 10 at.% in the CVD TaN films, as determined by Auger electron spectroscopy. From Rutherford backscattering spectroscopy and secondary ion mass spectroscopy analysis, TaN films were found to be effective diffusion barriers between aluminum and silicon up to 550 degrees C. The electrical measurements of diode-leakage current indicate that the Al/TaN/Si structure remained stable up to 500 degrees C, after which Al started to diffuse through the TaN layer and resulted in a higher leakage current.