Browsing by Author "Yu, CH"

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A physical model for the hysteresis phenomenon of the ultrathin ZrO2 film
(2002-10-01)
Wang, JC
;
Chiao, SH
;
Lee, CL
;
Lei, TF
;
Lin, YM
This work studies and presents an inner-interface trapping physical model for the ultra-thin (effective oxide thickness=15 Angstrom) zirconium oxide (ZrO2) film to explain its hysteresis phenomenon. The shift of the capacitance-voltage characteristics swept from accumulation to inversion and then swept back with light illumination is about 110 mV, which is larger than the shift without light illumination (similar to45 mV). The mobile ion effect is obviated using bias-temperature stress measurement. The proposed model successfully explains not only the phenomenon but also the thickness effect for the capacitance-voltage characteristics and the different turn-around voltages of the current density-voltage characteristics of the zirconium dielectrics. (C) 2002 American Institute of Physics.
Barrier characteristics of PECVD alpha-SiC : H dielectrics
(2001)
Chiang, CC
;
Wu, ZC
;
Wu, WH
;
Chen, MC
;
Ko, CC
This work investigates the thermal stability and barrier characteristics of three species of PECVD alpha-SiC:H dielectric films with dielectric constants between 3.5 and 5.4. It is found that the dielectric constant decreases with increasing content of carbon in the alpha-SiC:H film. All of the three specie's of alpha-SiC:H films are thermally stable at temperatures of up to 500degreesC. However, degraded barrier capability and moisture resistance were observed for the alpha-SiC:H film with a k value around 3.5, which has a C/Si atomic ratio of 0.875. This is presumably attributed to poorly crosslinked molecular structure and porosity enhancement by the abundant amount of carbon in the alpha-SiC:H film.
Changes of longitudinal vortex roll structure in a mixed convective air flow through a horizontal plane channel: An experimental study
(1997-01-01)
Chang, MY
;
Yu, CH
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
Flow visualization and temperature measurement were conducted to investigate the buoyancy induced longitudinal vortex how structure in a mixed convective air flow through a bottom heated horizontal plane channel for the Reynolds number ranging from 20 to 50 and Rayleigh number From 6000 io 30 000. The results suggested that at low buoyancy-to-inertia ratio a longitudinal roll pair with spanwise symmetry is first induced near the duct sides and more rolls are induced adjacent to the existing rolls as the flow moves downstream. Steady vortex flow prevails after the initial transient. At high buoyancy-to-inertia ratio the splitting and merging of the rolls take place frequently causing the flow to become unsteady and highly asymmetric at high Rayleigh numbers. Several types of the roll splitting processes were identified, namely, the splitting of one roll to three rolls and two rolls to four rolls, formation of two new rolls and two successive roll splittings of the above types. The reverse processes were noted during the roll merging. The data from the measured time histories of the air temperature indicated that the flow oscillation is position dependent with the oscillation amplitude being higher in the downstream core regions. Besides, the oscillation amplitude inside a roll is determined largely by the spanwise or axial position adjustment during the roll splitting and merging processes. Finally, the data for the onset of steady and unsteady vortex flows were empirically correlated. Copyright (C) 1996 Elsevier Science Ltd.
Comparative study of physical and electrical characteristics of F- and C-doped low-K CVD oxides
(2001)
Wu, ZC
;
Shiung, ZW
;
Chiang, CC
;
Wu, WH
;
Chen, MC
This work makes a comparative study of physical and electrical properties between two species of inorganic low-K CVD oxides, namely F-doped FSG (fluorinated silicate glass, K=3.5) and C-doped OSG (organosilicate glass, K=2.9). It is found that FSG has a higher thermal stability (>600degreesC) than OSG (500degreesC) based on the results of 30 min thermal anneal in N-2 ambient. The degradation of the low-K property in OSG is predominately due to the thermal decomposition of methyl (CH3) groups at temperatures above 500degreesC, which are incorporated to reduce the density and polarizability of OSG. For the Cu-gated oxide-sandwiched low-K dielectric MIS capacitors, Cu permeation was observed in both FSG and OSG after the MIS capacitors were subjected to bias-temperature stressing (BTS) at 250 and 150degreesC, respectively, with an effective applied field of 0.8 MV/cm. It appeared that Cu drifted more readily in OSG than in FSG presumably because OSG has a more porous and less dense structure than FSG. The Cu penetration can be efficiently mitigated by a thin nitride dielectric barrier layer.
Edge hole direct tunneling in off-state ultrathin gate oxide p-channel MOSFETs
(2000)
Yang, KN
;
Huang, HT
;
Chen, MJ
;
Lin, YM
;
Yu, MC
This paper examines the edge direct tunneling (EDT) of hole from p(+) polysilicon to underlying p-type drain extension in off-state p-channel MOSFETs having ultrathin gate oxide thicknesses (1.2 - 2.2 nm). It is found that for thinner oxide thicknesses, hole EDT is more pronounced over the conventional GIDL and gate-to-channel tunneling, and as a result, the induced gate and drain leakage is better measured per unit gate width. A physical model accounting for heavy and light hole's subbands in the quantized accumulation polysilicon surface is built explicitly. This model consistently reproduces EDT I-V and the tunneling path size extracted falls adequately within the gate-to-drain overlap region. The ultimate oxide thickness limit due to EDT is projected as well.
Effects of aspect ratio on vortex flow patterns in mixed convection of air through a bottom-heated horizontal rectangular duct
(1997-05-23)
Yu, CH
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
Buoyancy-induced vortex flow structures and the associated heat transfer were numerically investigated in a mixed convective airflow in a bottom-heated horizontal rectangular duct of different aspect ratios. The unsteady three-dimensional Navier-Stokes and energy equations were directly solved by a higher order upwind finite difference scheme. Results were presented in particular for Reynolds numbers ranging from 5 to 15, Rayleigh numbers up to 9000, and aspect ratios from 4 to 12. The predicted results clearly show significant differences in vortex structures induced in ducts with small and large aspect ratios. For an aspect ratio less than 6 the transverse vortex rolls are periodically generated in the duct entry and gradually transform into longitudinal rolls when moving downstream. The resulting vortex flow eventually evolves to a time periodic state with the upstream and downstream portions of the duct dominated by the transverse rolls and longitudinal rolls, respectively. For a large aspect ratio (A > 9) the transverse rolls prevail in the duct core, with two to three longitudinal rolls existing near each sidewall. The flow oscillation in the region dominated by the transverse rolls is much higher than that dominated by the longitudinal rolls. At high Ra the flow becomes chaotic in time, and the duct is filled with unstable irregular vortex rolls.
Electrical reliability issues of integrating low-K dielectrics with Cu metallization
(2000)
Wu, ZC
;
Shiung, ZW
;
Wang, CC
;
Fang, KL
;
Wu, RG
Electrical reliability issues of two organic aromatic low-K materials (K = 2.6 similar to 2.8) were investigated. Both materials show acceptable thermal stability and good dielectric barrier property against Cu penetration. C-V curve instability was observed under bias-temperature stress (BTS) for the first time. It can be explained by the model of stress induced dielectric polarization charges. This instability may be an issue of long term stability of circuits.
Enhancing the overwriting characteristics of phase-change optical disks by doping in dielectric layers
(2004-09-01)
Yu, CH
;
Hsieh, TE
;
Yeh, TT
;
Shieh, HPD
;
材料科學與工程學系
In this work, we studied the enhancement of overwriting characteristics of phase-change optical disks by doping in the dielectric layers. The doping elements included chromium (Cr), molybdenum (Mo), nickel (Ni), tantalum (Ta), titanium (Ti), tungsten (W), vanadium (V), and nitrogen (N-2) Dynamic test showed that doping with a certain amount of W and N-2 in dielectric layers enhanced the disk overwriting characteristics. Up to fortyfold improvement in disk cycleability was observed when N-2 gas was introduced during sputtering deposition of the upper dielectric layer at the gas flow rate of N-2/Ar = 25%. Tungsten was the best among the doping metallic elements resulting in fivefold improvement in disk cycleability. Optical property measurement revealed that the refractive index (n) decreased with increasing N-2 doping percentage, while the relatively small amount of metallic element doping negligibly changed the optical constants. Subsequent modulation simulation showed that such an optical property change is beneficial to disk overwriting characteristics. Nanoindentation test showed that N-2 doping was the most effective method for increasing the hardness of the dielectric layer. This implies that, with increasing mechanical strength, the dielectric layer possesses better resistance to thermal deformation resulting from laser heating, thereby enhancing the cycleability of optical disks.
Fabrication of NiSi2 nanocrystals embedded in SiO2 with memory effect by oxidation of the amorphous Si/Ni/SiO2 structure
(2005-07-01)
Yeh, PH
;
Wu, HH
;
Yu, CH
;
Chen, LJ
;
Liu, PT
NiSi2 nanocrystals embedded in the SiO2 layer exhibiting a memory effect have been formed by dry oxidation of an amorphous Si/Ni/SiO2 structure at 900 degrees C. A pronounced capacitance-voltage hysteresis was observed with a memory window of I V under the 2 V programming voltage for the samples. For dry oxidation at 800 degrees C, no distinct memory effect was detected. The processing of the structure is compatible with the current manufacturing technology of the semiconductor industry. The structure represents a viable candidate for low-power nanoscaled nonvolatile memory devices. (c) 2005 American Vacuum Society.
Flow visualization and numerical simulation of transverse and mixed vortex roll formation in mixed convection of air in a horizontal flat duct
(1997-05-01)
Chang, MY
;
Yu, CH
;
Lin, TF
;
機械工程學系
;
Department of Mechanical Engineering
Combined experimental flow visualization and three-dimensional unsteady numerical simulation were carried out to investigate the formation of the traveling transverse and mixed vortex roll structures from the initially unidirectional, subcritical flow of air in a bottom heated horizontal flat duct when the Rayleigh number was raised to a supercritical level. In the study the Reynolds number was varied from 2.5 to 20 and the Rayleigh number from 1500 to 8000. Both the experiment and computation, being in qualitative agreement, indicated that in the early stage of the transient a pair of longitudinal rolls are induced in the side wall region; then new longitudinal rolls were induced near the existing ones. Meanwhile, weak transverse rolls were generated in the duct entry. As time proceeds, the transverse rolls grow in size and strength and slowly move downstream to push the longitudinal rolls in front of them out of the duct. At the same time new transverse rolls are generated in the duct entry. Ar a low Reynolds number (Rr less than or equal to 5) the transverse rolls are longer and stronger to expel all the longitudinal rolls out of the test section so that a pure and regular transverse vortex roll structure is formed. While at a higher Reynolds number (Re greater than or equal to 7.5) the transverse rolls are shorter and weaker and a few longitudinal rolls stay, all the time, near the duct sides, resulting in a mixed longitudinal and transverse roll structure. In the numerical simulation the temporal characteristics of the two vortex flow structures at the statistical state are also examined in detail. (C) 1997 Elsevier Science Ltd.
Improvement of water-related hot-carrier reliability by optimizing the plasma-enhanced tetra-ethoxysilane deposition process
(1997-08-01)
Lin, YM
;
Jang, SM
;
Yu, CH
;
Lei, TF
;
電子工程學系及電子研究所
As-deposited, steam-exposed O-3-tetra-ethoxysilane (TEOS)-based intermetallic dielectric were characterized according to the LR-absorption spectra. The plasma-enhanced-TEOS films investigated here were formed by mixed-frequency plasma processes and differentiated by reaction oxidizers and/or plasma powers. Increasing stress and nitrogen or oxygen concentrations improved the moisture resistance of PE-TEOS oxide films. In addition to the moisture resistance of PE-TEOS films, another factor affecting hot-carrier robustness is the maximum thickness of the underlayer for O-3-TEOS films, which is limited by their conformity The integrated intermetallic dielectrics were evaluated by constant-current and hot-carrier stressing. In obtaining the best device reliability, a trade-off exists between moisture resistance, gapfilling capacity of the PE-TEOS underlayer, and plasma damage. Our results indicate that an O-2-rich, PE-TEOS film with a mechanical stress of 3 x 10(9) dyn/cm(2) is the optimum.
Improvement of water-related hot-carrier reliability by optimizing the plasma-enhanced tetra-ethoxysilane deposition process
(1997-08-01)
Lin, YM
;
Jang, SM
;
Yu, CH
;
Lei, TF
;
電子工程學系及電子研究所
As-deposited, steam-exposed O-3-tetra-ethoxysilane (TEOS)-based intermetallic dielectric were characterized according to the LR-absorption spectra. The plasma-enhanced-TEOS films investigated here were formed by mixed-frequency plasma processes and differentiated by reaction oxidizers and/or plasma powers. Increasing stress and nitrogen or oxygen concentrations improved the moisture resistance of PE-TEOS oxide films. In addition to the moisture resistance of PE-TEOS films, another factor affecting hot-carrier robustness is the maximum thickness of the underlayer for O-3-TEOS films, which is limited by their conformity The integrated intermetallic dielectrics were evaluated by constant-current and hot-carrier stressing. In obtaining the best device reliability, a trade-off exists between moisture resistance, gapfilling capacity of the PE-TEOS underlayer, and plasma damage. Our results indicate that an O-2-rich, PE-TEOS film with a mechanical stress of 3 x 10(9) dyn/cm(2) is the optimum.
Intelligent leaky bucket algorithms for sustainable-cell-rate usage parameter control in ATM networks
(2004-10-01)
Chang, CJ
;
Yu, CH
;
Chang, CS
;
Lin, LF
;
電信工程研究所
In this paper, we propose two intelligent leaky bucket algorithms for sustainable-cell-rate usage parameter control of multimedia transmission in asynchronous transfer mode networks. One is the fuzzy leaky bucket algorithm, in which a fuzzy increment controller (FIC) is incorporated with the conventional leaky bucket algorithm; the other is the neural fuzzy leaky bucket algorithm, where a neural fuzzy increment controller (NFIC) is added with the conventional leaky bucket algorithm. Both the FIC and the NFIC properly choose the long-term mean cell rate and the short-term mean cell rate as input variables to intelligently determine the increment value. Simulation results show that both intelligent leaky bucket algorithms have significantly outperformed the conventional leaky bucket algorithm, by responding about 160% faster when taking control actions against a nonconforming connection while reducing as much as 50% of the queueing delay experienced by a conforming connection. In addition, the neural fuzzy leaky bucket algorithm outperforms the fuzzy leaky bucket algorithm, in aspects of three performance measures such as selectivity, responsiveness, and queueing delay, especially when the traffic flow is bursty, dynamic, and nonstationary.
Leakage mechanism in Cu damascene structure with methylsilane-doped low-K CVD oxide as intermetal dielectric
(2001-06-01)
Wu, ZC
;
Chiang, CC
;
Wu, WH
;
Chen, MC
;
Jeng, SM
This letter investigates the leakage mechanism in the Cu damascene structure with methylsilane-doped low-k CVD organosilicate glass (OSG) as the intermetal dielectric (IMD), The leakage between Cu lines was found to be dominated by the Frenkel-Poole (F-P) emission in OSG for the structure using a 50-nm SiC etching stop layer (ESL), In the structure using a 50-nm SiN ESL, the leakage component through SiN also made a considerable contribution to the total leakage in addition to the bulk leakage from trapped electrons in OSG, An appropriate ESL of sufficient thickness is essential to reduce the leakage through the ESL if an ESL is used in the Cu damascene integration scheme.
Numerical performance and throughput benchmark for electronic structure calculations in PC-Linux systems with new architectures, updated compilers, and libraries
(2004-03-01)
Yu, JSK
;
Hwang, JK
;
Tang, CY
;
Yu, CH
;
生物科技學系
A number of recently released numerical libraries including Automatically Tuned Linear Algebra Subroutines (ATLAS) library, Intel Math Kernel Library (MKL), GOTO numerical library, and AMD Core Math Library (ACML) for AMD Opteron processors, are linked against the executables of the Gaussian 98 electronic structure calculation package, which is compiled by updated versions of Fortran compilers such as Intel Fortran compiler (ifc/efc) 7.1 and PGI Fortran compiler (pgf77/pgf90) 5.0. The We 7.1 delivers about 3% of improvement on 32-bit machines compared to the former version 6.0. Performance improved from pgf77 3.3 to 5.0 is also around 3% when utilizing the original unmodified optimization options of the compiler enclosed in the software. Nevertheless, if extensive compiler tuning options are used, the speed can be further accelerated to about 25%. The performances of these fully optimized numerical libraries are similar. The double-precision floating-point (FP) instruction sets (SSE2) are also functional on AMD Opteron processors operated in 32-bit compilation, and Intel Fortran compiler has performed better optimization. Hardware-level tuning is able to improve memory bandwidth by adjusting the DRAM timing, and the efficiency in the CL2 mode is further accelerated by 2.6% compared to that of the CL2.5 mode. The FP throughput is measured by simultaneous execution of two identical copies of each of the test jobs. Resultant performance impact suggests that IA64 and AMD64 architectures are able to fulfill significantly higher throughput than the IA32, which is consistent with the SpecFPrate2000 benchmarks.
Photochemistry and photodissociation of benzosultine and naphthosultine: electronic relaxation of sultines and kinetics and theoretical studies of fragment o-quinodimethanes
(2005-02-28)
Tang, KC
;
Lee, SJ
;
Chi, SH
;
Lu, KL
;
Chen, WC
Fluorescence decays of benzosultine and naphthosultine excited at 263 nm are detected with time-correlated single-photon counting (TCSPC). Both molecules display biexponential decay with a rapid component (time constants 90 and 350 ps for benzosultine and naphthosultine, respectively) assigned to an electronically excited state S-n at high energy and the slow one (constants 7.5 and 9.0 ns for benzosultine and naphthosultine, respectively) to the S-1 state. Dissociation of both molecules was investigated with nanosecond laser flash photolysis combined with transient absorption to detect the intermediates and products. With excitation at 266 nm, benzosultine yields a transient with absorption maximum at lambda(max) = 370 nm; this transient has a short-lived component with lifetime around 1 mus and a long-lived component. Both components are insensitive to molecular oxygen. The short-lived component is tentatively assigned to the dissociation intermediate and the long-lived to be singlet o-benzoquinodimethane (o-BQDM). Photolysis of naphthosultine yields two transient species with absorption at; lambda(max) = 420 and 520 nm; we assign the former band to triplet-triplet absorption of naphthosultine and the latter to absorption by the product singlet o-naphthoquinodimethane. Optimal geometries, energetics, and vertical transitions of benzosultine, naphthosultine, o-benzoquinodimethane, and o-naphthoquinodimethane are calculated using methods based on density-functional theory (B3LYP/6-311++G**) and time-dependent density-functional theory (TD-DFT). The results of these calculations imply that the ground electronic state of these two o-quinodimethanes (o-QDM) is singlet with a structure of diene form. Their triplet states display a biradical structure. The energy separation between singlet and triplet states of o-benzoquinodimethane is calculated to be ca. 93.6 kJ/mol, but for o-naphthoquinodimethane, it is only ca. 27.8 kJ/mol. (C) 2004 Elsevier B.V. All rights reserved.
Physical and barrier properties of plasma enhanced chemical vapor deposition alpha-SiC : N : H films
(2003-07-01)
Chiang, CC
;
Wu, ZC
;
Wu, WH
;
Chen, MC
;
Ko, CC
In this work, we investigate the thermal stability and physical and barrier properties of three species of plasma enhanced chemical vapor deposition (PECVD) alpha-SiC:N:H silicon carbide films with different carbon and nitrogen contents and dielectric constants less than a value of 5.5. For comparison, one species of alpha-SiN:H film with a k value of 7.2 is also studied. It is found that the dielectric constant decreases with increasing content of carbon and decreasing content of nitrogen in the alpha-SiC:N:H film. All of the three species of alpha-SiC:N:H and the one species of alpha-SiN:H films are thermally stable at temperatures up to 500degreesC. However, degraded barrier capability and moisture resistance were observed for the alpha-SiC:N:H film with a k value of 3.5, which has a C/Si atomic ratio of 0.875. This is presumably due to the poorly crosslinked molecular structure and porosity enhancement caused by the abundant amount of carbon in the alphaSiC:N:H film.
Physical and barrier properties of plasma-enhanced chemical vapor deposited alpha-SiCN : H films with different hydrogen contents
(2003-08-01)
Chiang, CC
;
Chen, MC
;
Ko, CC
;
Jang, SM
;
Yu, CH
This work investigates the thermal stability and physical and barrier properties of two species of plasma-enhanced chemical-vapor-deposited (PECVD) amorphous silicon-nitrocarbide (alpha-SiCN:H) films with different hydrogen contents and dielectric constants of less than 5. It is found that the alpha-SiCN:H film with a higher hydrogen content has a lower dielectric constant. Both species of alpha-SiCN:H films are thermally stable at temperatures up to 500degreesC. However, a degraded dielectric strength was observed for the alpha-SiCN:H film with a lower k-value of 4, which has a much higher hydrogen content. This may be attributed to hydrogen-related defects, such as Si-H+-Si hydrogen bridges, and numerous Si-H weak bonds produced by the high hydrogen content in the alpha-SiCN:H film.
Physical and electrical characteristics of F- and C-doped low dielectric constant chemical vapor deposited oxides
(2001-06-01)
Wu, ZC
;
Shiung, ZW
;
Chiang, CC
;
Wu, WH
;
Chen, MC
This work compares the physical and electrical properties of two species of inorganic low dielectric constant (low-k) chemical vapor deposited (CVD) oxides, F-doped fluorinated silicate glass (FSG, k = 3.5) and C-doped organosilicate glass (OSG, k = 2.9). Experimental results indicate that FSG has a higher thermal stability >600 degreesC! than OSG (500 degreesC), based on the results of thermal annealing for 30 min in an N-2 ambient. The degradation of the low-k property in OSG is mainly due to the thermal decomposition of methyl (-CH3) groups at temperatures above 500 degreesC. For the Cu gated oxide-sandwiched low-k dielectric metal-insulator-semiconductor (MIS) capacitors, Cu penetration was observed in both FSG and OSG after the MIS capacitors were bias-temperature stressed at 250 and 150 degreesC, respectively, with an effective applied field of 0.8 MV/cm. Specifically, Cu appeared to drift more readily in OSG than in FSG, presumably because OSG has a more porous and less dense structure than FSG. The Cu permeation can be impeded by a thin nitride (SiN) barrier layer. (C) 2001 The Electrochemical Society.
Physical and electrical characteristics of methylsilane- and trimethylsilane-doped low dielectric constant chemical vapor deposited oxides
(2001-06-01)
Wu, ZC
;
Shiung, ZW
;
Chiang, CC
;
Wu, WH
;
Chen, MC
This work investigates the physical and electrical properties of two species of inorganic C-doped low dielectric constant (low-k) chemical vapor deposited (CVD) organosilicate glasses (OSGs, alpha -SiCO:H). They are both deposited by plasma-enhanced CVD (PECVD) processes using methylsilane [(CH3)SiH3, 1 MS]- and trimethylsilane [(CH3)(3)SiH, 3 MS]-based gases as the reagents, and are designated as OSG1 and OSG2, respectively. Experimental results indicate that the thermal stability temperature of OSG1 is 500 degreesC, while that of OSG2 is 600 degreesC, based on the results of thermal annealing for 30 min in an N-2 ambient. The deterioration of the low-k property in OSG1 is predominately due to the thermal decomposition at temperatures above 500 degreesC of methyl (-CH3) groups, which are introduced to lower the density and polarizability of OSGs. For the Cu-gated oxide-sandwiched low-k dielectric metal-insulator-semiconductor (MIS) capacitors, Cu permeation was observed in both OSG1 and OSG2 after the MIS capacitors were bias-temperature stressed at 150 degreesC with an effective applied field of 0.8 MV/cm. Moreover, Cu appeared to drift more readily in OSG1 than in OSG2, presumably because OSG1 has a more porous and less cross-linked structure than OSG2. The Cu penetration can be mitigated by a thin nitride dielectric barrier. (C) 2001 The Electrochemical Society.