Browsing by Author "Tsai, MH"

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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
An efficient improvement for barrier effect of W-filled contact
(1996-02-01)
Yeh, WK
;
Chan, KY
;
Chang, TC
;
Tsai, MH
;
Chen, SH
A post chemical vapor deposition of tungsten (CVD-W) treatment by N-2 plasma is proposed to suppress the WAl12 formation during subsequent thermal annealing, which improves the thermal stability of W-filled contact. Selective CVD-W is employed to fill the contact hole. Following W deposition, in situ N-2 plasma treatment is performed prior to Al alloy metallization. It is shown that this post CVD-W treatment efficiently suppresses the formation of WAl12, resulting in an improvement of the barrier capability of W-filled contact.
Anion-terminated zinc-blende CdS(100) surface
(1997-10-15)
Lin, CM
;
Tsai, MH
;
Yang, TJ
;
Chuu, DS
;
電子物理學系
Using the local-orbital density-functional molecular-dynamics method, we have studied the surface structure of the strain-stabilized zinc-blende monolayer anion-terrainated CdS(100) surface. By analogy with the GaAs(100) surface, we have considered four structural models and found that the structure with a (2 x 4) unit cell, in which there are a two-dimer unit and a two-shifted-dimer unit, is the most favorable. These results can be understood in terms of physical properties associated with ionicity.
Caching in I-CSCF of UMTS IP multimedia subsystem
(2006-01-01)
Lin, YB
;
Tsai, MH
;
資訊工程學系
;
Department of Computer Science
The IP multimedia core network subsystem (IMS) provides multimedia services for Universal Mobile Telecommunications System (UMTS). In IMS, any incoming call will first arrive at the interrogating call session control function (I-CSCF). The I-CSCF queries the home subscriber server (HSS) to identify the serving CSCF (S-CSCF) of the called mobile user. The S-CSCF then sets up the call to the called mobile user. This paper investigates the performance of the IMS incoming call setup. We also propose cache schemes with fault tolerance to speed up the incoming-call-setup process. Our study indicates that the I-CSCF cache can significantly reduce the incoming-call-setup delay, and checkpointing can effectively enhance the availability of I-CSCF.
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.
Comparison of the electronic structures of AIN nanotips grown on p- and n-type Si substrates
(2005-12-07)
Chiou, JW
;
Tsai, HM
;
Pao, CW
;
Dong, CL
;
Chang, CL
At and N K-edge x-ray absorption near-edge structure (XANES), scanning photoelectron microscopy (SPEM) and x-ray emission measurements were performed on AIN nanotips grown on p- and n-type Si substrates (p-AIN and n-AIN). Features and intensities in the Al and N K-edge XANES spectra of these AIN nanotips overall are similar. In contrast, the intensities of the valence-band SPEM spectra of p-AIN are apparently larger than those of n-AIN, which indicates that the valence-band density of states of p-AIN exceeds that of n-AIN. This result may be related to the observed enhancement of field-emission intensity of AIN nanotips grown on the p-type Si substrate.
Direct experimental evidence of hybridization of Pb states with O 2p states in ferroelectric perovskite oxides
(2005-07-04)
Jan, JC
;
Tsai, HM
;
Pao, CW
;
Chiou, JW
;
Asokan, CK
This work presents the O K- and Ti L-3,L-2-edge x-ray absorption near-edge structure (XANES) spectra of PbxSr1-xTiO3 (PxSTO) and BaxSr1-xTiO3 (BxSTO) compounds with various Pb and Ba concentrations. The result provides direct evidence that the Pb-O bonding strongly affects O 2p-Ti 3d hybridization in the TiO6 octahedron of PxSTO. In contrast, the Ba-O bonding does not substantially affect O 2p-Ti 3d hybridization in BxSTO. The Ti L-3-edge XANES spectra show the splitting of the e(g) band for PxSTO with x greater than or similar to 0.5, which provides an evidence of Pb-induced tetragonal distortion in the TiO6 octahedron. In contrast, e(g) band splitting is absent in BxSTO. (c) 2005 American Institute of Physics.
Dynamic mechanical properties of polyimide/poly(silsesquioxane)-like hybrid films
(2001-09-06)
Tsai, MH
;
Whang, WT
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Polyimide/poly(silsesquioxane)-like (PI/PSSQ-like) films have three-dimensional structure with linear PI blocks and a crosslinked PSSQ-like structure. They have higher thermal stability and char yields than pure PI from 4,4'-diaminodiphenyl ether and 3, 3'-oxydiphthalic anhydride (ODPA). In a series of X-PIS [PI modified with p-aminophenyltrimethoxysilane (APTS), where X is the molecular weight of each PI block] hybrid films, decreasing the PI block chain length enhances the storage modulus, tensile modulus, and glass-transition temperature (T-g) but reduces the alpha -relaxation damping peak intensity, density, and elongation. The change in the former three properties may be caused by an increase in the crosslinking density and rigidity of the network structure. The changes in the next two properties are caused by an increase in the free volume or the PI interblock separation and decreases in the interblock PI chain interaction. The change in the last property (i.e., a decrease in elongation) is related to the increase in the rigidity of the network structure. The activation energy of the a transition depends on the chain length of the PI block. A maximum value is reached at the chain length of 10,000 because of two different factors: crosslinking density and free volume. In a series of X-PIS-y-PTS [X-PIS modified with phenyltrimethoxysilane (PTS), where y is the weight-ratio percentage of PTS to APTS-polyamic acid] films with a constant PI block length, the storage modulus, tensile modulus, T-g, density, and alpha -relaxation damping peak intensity decrease with the PTS content. This could be because of the increase of the PSSQ-like domain size with the PTS content, which leads to the introduction of more free volume or interblock separation and to a decrease in the interblock chain interaction force. (C) 2001 John Wiley & Sons, Inc.
Effect of rapid thermal annealing on the electrical and physical properties of metalorganic chemical-vapor-deposited TiN
(1996-01-29)
Sun, SC
;
Tsai, MH
;
奈米中心
;
Nano Facility Center
This work reports on the effect of postdeposition thermal treatment using rapid thermal annealing on the physical and electrical properties of metalorganic chemical-vapor-deposited (MOCVD) titanium nitride (TiN) thin films. When ammonia is used as the annealing ambient, the resistivity decreases with increasing annealing temperature. The resistivity of MOCVD TiN was reduced from 6000 to 320 mu Omega cm after 800 degrees C rapid thermal annealing in ammonia (RTN). Annealing in nitrogen ambient was found to be not nearly as effective as that in ammonia. The decrease in resistivity may be attributed to a reduction in the carbon and oxygen content, growth in grain size through polycrystalline recrystallization, as well as to an increase in film density. (C) 1995 American Institute of Physics.
Effect of the Ca content on the electronic structure of Pb1-xCaxTiO3 perovskites
(2003-10-20)
Jan, JC
;
Kumar, KPK
;
Chiou, JW
;
Tsai, HM
;
Shih, HL
This study performs O K- and Ti L-3,L-2-edge x-ray absorption near-edge structure (XANES) measurements and first-principles pseudopotential calculations for the electronic structures of ABO(3)-type Pb1-xCaxTiO3 (x=0-1) perovskites. The features in the O K-edge XANES spectra are found to be contributed primarily by hybridization between O 2p and Ti 3d, Pb 6p, and Ca 3d orbitals. The O K-edge XANES spectra reveal that partial substitution of A cations, Pb, by Ca not only decreases O 2p-Pb 6p but also O 2p-Ti 3d hybridization. The Ti L-3,L-2-edge measurements find that the off-center displacement of Ti, and hence, ferroelectricity persist up to a Ca concentration between 0.3 and 0.4. (C) 2003 American Institute of Physics.
Electrical characteristics and annealing study of boron-doped polycrystalline diamond films
(1995-12-01)
Chen, SH
;
Chen, SL
;
Tsai, MH
;
Shyu, JJ
;
Chen, CF
Annealing processes are an important area of fundamental research within the field of diamond electronic applications. In this study, annealing was applied to as-grown boron-doped diamond films. The current-voltage (I-V) characteristics of the Al/boron-doped diamond films were also investigated. First, the conductivity of films was examined to determine the effect of annealing on boron-doped diamond films. Experimental results indicated that the activation energy for the as-deposited diamond films (intrinsic or light boron-doped) is about 0.38 eV. After annealing, the activation energy did not change. However, the activation energy of the heavily doped films remarkably would change to 0.014 eV after annealing. Next, Fourier transform infrared spectroscopy (FTIR) and cathodoluminescence (CL) were performed to understand more clearly the correlation between the activation energy and the annealing effect on B-doped diamond films. These results revealed that for the lightly B-doped films, the boron atoms were effectively activated at the substitutional site. For the heavily doped case, boron was initially located in an inactive site (e.g., grain boundary, interstitial or clustering sites) and would diffuse into the substitutional site after 900 degrees C annealing.
Electrical characteristics and deep-level admittance spectroscopies of low-temperature grown GaAs p-i-n structures
(1997-02-01)
Chen, JF
;
Chen, NC
;
Wang, PY
;
Tsai, MH
;
交大名義發表
The properties of low-temperature grown GaAs are studied via the electrical characterization of p-i-n structures with part of the intrinsic layer grown at 300 degrees C. Comparisons are made between the low-temperature and normally grown samples. The current of the low-temperature sample is about two orders of magnitude higher than that of the normally grown sample in both forward and reverse bias. From temperature-dependent analysis, the leakage current of the low-temperature sample is contributed by the recombination current through defect levels around the midgap, from which a recombination lifetime of 9.4X10(-12) a was obtained. By using admittance spectroscopy we observed a dominant electron level at 0.60 eV with a corresponding capture cross section of 1.0x10(-13) cm(2) that was not observed in the normally grown sample; thus it is believed to be introduced by the As-rich low-temperature layer. (C) 1997 American Institute of Physics.
Growth mechanism and properties of the large area well-aligned carbon nano-structures deposited by microwave plasma electron cyclotron resonance chemical vapor deposition
(2002-03-01)
Lin, CH
;
Chang, HL
;
Tsai, MH
;
Kuo, CT
;
材料科學與工程學系
Large area (4-inch diameter) well-aligned carbon nano-structures on Si substrate were successfully synthesized by using a catalyst-assisted microwave plasma electron cyclotron resonance chemical vapor deposition (ECR-CVD) system with CH4 as source gas. The catalysts include Fe, Co and Ni. The catalysts and the deposited nano-structures were characterized by scanning electron microscopy (SEM) transmission electron microscopy (TEM), Raman and field emission I-V measurements. Effects of process parameters on morphologies, structures and properties of the nano-structures were examined. The results show that the deposited nano-structures can include normal nano-tubes, split catalyst nano-tubes, seaweed-like nano-sheets and carbon film, depending mainly on substrate temperature and bias, catalyst materials and their application methods. Deposition mechanisms for different nano-structures, especially, the unique split catalyst nano-tubes and seaweed-like nano-sheets, were proposed. The differences in oxidation resistance and field emission proper-ties between different nano-structures will be compared and discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
High temperature lifetime of polyimide/poly(silsesquioxane)-like hybrid films
(2001-06-01)
Tsai, MH
;
Whang, WT
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Decomposition kinetics in thermogravimetric analysis (TGA) and dynamic mechanical relaxation in dynamic mechanical analysis (DMA) are used to study the high temperature lifetime of the new type of polyimide/poly(silsesquioxane)-like (PI/PSSQ-like) hybrid films, which are designed to form three-dimensional structures with linear polyimide blocks and a crosslinked PSSQ-like structure. Both TGA and DMA analysis reveal that the PI/PSSQ-like hybrid films have a longer lifetime (are more reliable) with regard to their thermal and mechanical characteristics than that of pure PI. Even just 2 wt% of p-aminophenyltrimethoxysilane (APTS) in a PI/PSSQ-like hybrid film can significantly improve the service lifetime by as much as at least four times in a TGA decomposition kinetic study. The dynamical relaxation data are well fitted to the calculated WLF (Williams-Landel-Ferry) master curves. In a series of X-PIS (PI modified with APTS) hybrid films, decreasing the PI block chain length increases the decomposition activation energy, lifetime (in both TGA and DMA) and relaxation modulus. In a series of X-PIS-y-PTS [PI modified with APTS and phenyltrimethoxysilane (PTS)] films, the decomposition activation energy and lifetime (in TGA) increase with the PTS content. Interestingly, the dynamic mechanical relaxation modulus of 10000-PIS-100-PTS film is lower than that of the corresponding 10000-PIS film at frequency > 10(2) rad/sec, but higher at frequency < 10(2) rad/sec. The 10000-PIS-100-PTS has a lower relaxation time than the 10000-PIS at the modulus 5x10(8) Pa, but the relaxation time of the former becomes higher at 5x10(7) Pa.
Low dielectric polyimide/poly(silsesquioxane)-like nanocomposite material
(2001-04-01)
Tsai, MH
;
Whang, WT
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A new type of low dielectric polyimide/poly(silsesquioxane)-like (PI/PSSQ-like) hybrid nanocomposite material is successfully prepared from the polyimide (ODA-ODPA) precursor containing phenyltrialkoxysilane IPTS) at two chain ends and monoaryltrialkoxysilane with a self-catalyzed sol-gel process. We employ p-aminophenyltrimethoxysilane (APTS) to provide bonding between the PTS and ODPA-ODA phase, It is shown by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) that the PSSQ-like domain sizes with uniform size are fairly well separated in the hybrid films. The silica domain sizes of 5000-PIS and 5000-PIS-50-PTS films are in the range of 30-100 nm, of 5000-PIS-100-PTS and 10000-PIS-100-PTS in the range of 80-200 and 300-600 nm, respectively. The dielectric constant can be 2.79 for 5000-PIS-140-PTS with fairly good mechanical properties. The PI/PSSQ-like hybrid films have higher onset decomposition temperature and char yield in thermogravimetric analysis (TGA) and higher T-g in differential scanning calorimetry (DSC) than the pure PI. Moreover, the PI/PSSQ-like hybrid films have excellent transparency even under high PTS content. In the series of X-PIS hybrid films, the coefficient of thermal expansion (CTE) below T-g increases with the PI block chain length, but in the series of X-PIS-y-PTS films, it slightly increases with the PTS content. However, above T-g the CTE of X-PIS and X-PIS-24-PTS is much lower than that of the pure PI. The dielectric constant and water absorption of X-PIS-V-PTS films decrease with the PTS content because of the higher free volume and hydrophobicity. (C) 2001 Elsevier Science Ltd. All rights reserved.
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.
Metalorganic chemical vapor deposition of tungsten nitride for advanced metallization
(1996-03-04)
Tsai, MH
;
Sun, SC
;
Chiu, HT
;
Chuang, SH
;
電子工程學系及電子研究所
In this study, the physical and electrical properties of tungsten nitride thin films deposited by thermal decomposition of bis(tertbutylimido)bis(tertbutylamido)tungsten have been investigated. The films have an excellent step coverage over high aspect-ratio contact holes as well as a low carbon concentration. Strong W-N double bonds in the precursor preserved the nitrogen atoms during the pyrolysis process. This method subsequently yielded low-resistivity films. A decrease in film resistivity from 4300 to 620 mu Ohm cm corresponded to an increase in the deposition temperature from 500 to 650 degrees C, X-ray diffraction (XRD) and wavelength dispersive spectroscopy (WDS) results indicated that the as-deposited films have face centered cubic (fcc) phase polycrystalline structures with excessive nitrogen atoms. (C) 1996 American Institute of Physics.
Performance of MOCVD tantalum nitride diffusion barrier for copper metallization
(1995)
Sun, SC
;
Tsai, MH
;
Tsai, CE
;
Chiu, HT
;
奈米中心
Physical and mechanical properties of polyimide/titania hybrid films
(2004-01-30)
Chiang, PC
;
Whang, WT
;
Tsai, MH
;
Wu, SC
;
材料科學與工程學系
Titania-containing polyimide (PI) hybrid films with homogeneous and flexible properties have been fabricated via sol-gel process. Various contents of titania are added to three different PI systems by using acetylacetone to reduce the reaction rate and to prohibit gelation. The thermal, electrical and mechanical properties of the hybrid films will be measured and compared to pure PI. Results indicate that the metal-containing PI possesses lower thermal expansion and resistivity than pure PI. Incorporation of small amount of titania enhances mechanical properties of the hybrid films at both low and elevated temperature. The relationship between the effect of titania concentration, structure and properties will also be discussed. (C) 2003 Elsevier B.V. All rights reserved.