Browsing by Issue Date, starting with "1995-12-01"

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Electrical properties of diamond films grown at low temperature
(1995-12-01)
Chen, CF
;
Chen, SH
;
Lin, KM
;
交大名義發表
;
材料科學與工程學系
The unique electronic properties of diamond, associated with the emergence of chemical vapour deposition (CVD) methods for the growth of thin films on non-diamond substrates, have led to considerable interest in electronic devices fabricated from this material. In our previous work, we found that polycrystalline diamond films can be deposited at 250 degrees C using CH4-CO2 gas mixtures. Studying the electrical properties and the upcoming problems of applications of low-temperature diamond films are relevant concerns. In this work, the electrical properties of diamond films grown at low temperatures were studied and compared with those of conventional diamond films. Platinum was used as the upper electrode. The resistivity of low-temperature diamond was around three orders of magnititude lower than that of conventional diamond. However, both the low temperature and conventional growth diamond exihibited rectifying behavior when platinum was used as the upper electrode.
Growth of SiC films on Si(100) by electron cyclotron resonance chemical vapor deposition using SiH4/CH4/H-2
(1995-12-01)
Liu, CC
;
Lee, CP
;
Cheng, KL
;
Cheng, HC
;
Yew, TR
SiC films were deposited on Si(100) substrates by electron cyclotron resonance chemical vapor deposition at 500 degrees C using SiH4/CH4/H-2 gas mixtures. The chemical composition and crystalline microstructure were investigated by x-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy, respectively. The film composition and microstructure are correlated to process variables. The deposition mechanism which controls the film characteristics is presented.
Effect of nitrogen on diamond growth using unconventional gas mixtures
(1995-12-01)
Hong, TM
;
Chen, SH
;
Chiou, YS
;
Chen, CF
;
交大名義發表
The influence of nitrogen on the growth of diamond using unconventional gas mixtures of CH4-CO2 by microwave plasma chemical vapor deposition was investigated. A clear improvement in the surface morphology and quality of the diamond films indicates the beneficial effect of adding nitrogen to CH4-CO2 gas mixtures. However, most interestingly, for lower methane concentration, the addition of small amounts of nitrogen resulted in the formation of isolated diamond particles possessing a vacant ''cage-like'' structure with completed (100) facets. This result indicates that the continued addition of nitrogen gives rise to the deterioration of (111) facets and the retention of (100) facets. Analysis using Auger electron spectroscopy and secondary ion mass spectroscopy shows very low and uniform levels of nitrogen in the diamond films. Although the amount of atomic hydrogen in the ground state decreased and CN radicals increased with increasing amounts of added nitrogen, good-quality diamond films were deposited resulting from a larger amount of atomic oxygen and the decrease in the C-2 emissions in the gas phase under optimum conditions.
Fuzzy logic approach for removing noise
(1995-12-01)
Lee, YG
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Hsueh, YC
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交大名義發表
;
資訊工程學系
;
National Chiao Tung University
This paper shows how fuzzy reasoning techniques can be applied on smoothing filters design. It uses the fuzzy concept to decide whether a pixel in an image is a noise one or not in order to achieve maximum noise reduction in uniform areas and preserve details as well.
STRUCTURAL EFFECT ON BAND-TRAP-BAND TUNNELING INDUCED DRAIN LEAKAGE IN N-MOSFETS
(1995-12-01)
WANG, TH
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CHANG, TE
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HUANG, CM
;
YANG, JY
;
CHANG, KM
The structural dependence of the hot carrier stress incurred drain leakage current via band-trap-band tunneling in off-state has been modeled and characterized in conventional S/D, DDD, and LDD n-MOSFET structures, The results shows that lateral field enhanced band-trap-band tunneling is primarily responsible for an increased drain leakage current after hot carrier stress in LDD structures while vertical field induced tunneling is dominant in conventional S/D and DDD structures.
CHARACTERISTICS OF TOP-GATE THIN-FILM TRANSISTORS FABRICATED ON NITROGEN-IMPLANTED POLYSILICON FILMS
(1995-12-01)
YANG, CK
;
LEI, TF
;
LEE, CL
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The electrical characteristics of top-gate thin-film transistors (TFT's) fabricated on the nitrogen-implanted polysilicon of the doses ranging from 2 x 10(12)-2 x 10(14) ions/cm(2) were investigated in this work, The experimental results showed that nitrogen implanted into polysilicon followed by an 850 degrees C 1 h annealing step had some passivation effect and this effect was much enhanced by a following H-2-plasma treatment. The threshold voltages, subthreshold swings, ON-OFF current ratios, and field effect mobilities of both n-channel and p-channel TFT's were all improved, Moreover, the hot-carrier reliability was also improved, A donor effect of the nitrogen in polysilicon was also found which affected the overall passivation effect on the p-channel TFT's.
A 2-PHASE ENCRYPTION SCHEME FOR ENHANCING DATABASE-SECURITY
(1995-12-01)
HWANG, MS
;
YANG, WP
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資訊工程學系
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Department of Computer Science
In this article, we propose a two-phase encryption algorithm for data base systems. The system, a record-oriented cryptosystem, allows the encryption and decryption of fields within a record by means of writing and reading subkeys of fields. In addition, we develop two algorithms for cryptographic relational algebra in data base systems. Two simple methods of solving the key management problem in the subkey scheme are presented.
CHARACTERISTICS OF POLYCRYSTALLINE FILMS GROWN BY ULTRAHIGH-VACUUM CHEMICAL-VAPOR-DEPOSITION SYSTEM
(1995-12-01)
LIN, HY
;
LEI, TF
;
LIN, HC
;
CHANG, CY
;
TWU, RC
In situ boron-doped polycrystalline Si1-xGex (poly-Si1-xGex) films deposited by ultrahigh vacuum chemical vapor deposition (UHV/CVD) system were characterized. Optimum fitted values of grain boundary trap state densities, 4.0 x 10(12) cm(-2) and 4.9 x 10(12) cm(-2) were obtained for poly-Si and poly-Si0.79Ge0.21, respectively. The extracted average carrier concentration in the grain agrees with secondary ion mass spectroscopy (SIMS) analysis. In turn, we found that these films are suitable Hall elements to sense magnetic field. Experimental results show that the sensitivity decreased with the increasing input current, which can be well explained using the thermionic emission theory. Finally, we use these films to fabricate thin film transistors.
Electrical characteristics and annealing study of boron-doped polycrystalline diamond films
(1995-12-01)
Chen, SH
;
Chen, SL
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Tsai, MH
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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.
TIMING-DRIVEN PARTIAL SCAN
(1995-12-01)
JOU, JY
;
CHENG, KT
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This partial scan approach reduces area overhead and performance degradation caused by test logic. Given an initial design that meets a target speed, the authors' algorithm selects a set of scan flip-flops that allows the circuit to meet performance requirements after the scan logic is added. if no such set exists, the algorithm selects a set that minimizes the total area increase caused by the scan logic and the subsequent performance optimization the circuit requires to meet target speed.
Remote scheme for password authentication based on theory of quadratic residues
(1995-12-01)
Chang, CC
;
Tsu, SM
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Chen, CY
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資訊工程學系
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Department of Computer Science
We propose a remote password authentication scheme based on quadratic residues. In our schemer any legal user can freely choose his own password in the card initialization phase. Using his password and smart card which contains identity and other information, he can then log into the system successfully. According to our analysis, intruders cannot obtain any secret information from the public information, or derive any password from intercepted messages. In addition, our scheme can withstand the attack of replaying previously intercepted log-in requests.
Thermal stability of AlSiCu/W/n(+)p diodes with and without TiN barrier layer
(1995-12-01)
Yeh, WK
;
Chen, MC
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Wang, PJ
;
Liu, LM
;
Lin, MS
Thermal stability of AlSiCu/W/n(+)p diodes with two different W contact structures prepared by selective W chemical vapour deposition (W-CVD), was first investigated. The diodes with the self-aligned W-contacted structure were able to sustain a 30 min furnace annealing up to 500 degrees C without degradation of electrical characteristics. The diodes with the contact-hole W-contacted structure were thermally less stable than the diodes with the self-aligned W-contacted structure, presumably because the sidewall of the W-filled contact hole provided a path for diffusion of Al into the Si substrate, leading to junction spiking. The insertion of a 400 Angstrom TiN barrier layer between the AlSiCu and W films blocked the Al diffusion path; thus, the AlSiCu/TiN/W/n(+)p diode was able to retain its integrity up to 550 degrees C furnace annealing.
Temperature cycling effects between Sn/Pb solder and electroless copper plated AIN substrate
(1995-12-01)
Chiou, BS
;
Chang, JH
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Duh, JG
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
Thermal cycling effects on Sn/Pb solder and electroless Cu-plated AIN substrates are investigated. X-ray diffraction patterns reveal the existence of Cu2O for the electroless Cu-plated AIN after thermal cycling in an environmental chamber. Moisture in the chamber results in the oxidation of electroless plated Cu and fracture takes place at the Cu2O/Cu interface. The oxidation of Cu is also confirmed by Auger depth profile and electrical sheet resistance measurement. For the solder/Cu/AIN system, fracture occurs at the Cu/solder interface. No intermetallic compounds between solder and Cu are found after thermal cycling. Stress resulting from the thermal expansion mismatch is the major cause of loss of adhesion.
Experimental characterization of the vibrational behavior of a fluid-filled thin shell for the purpose of response estimation
(1995-12-01)
Bai, MR
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Lin, YY
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交大名義發表
;
機械工程學系
;
National Chiao Tung University
Experimental techniques are proposed for developing a model to estimate structural vibrations induced by internal acoustic pressure at low frequencies. In these methods, the acoustic field and the structure are treated as a coupled system with the acoustic loading effect taken into account. The response model between the internal pressure and the surface vibration is established by a modified modal test on the coupled system. Experiments are performed to investigate the surface vibrations of a closed steel cylindrical shell excited by a loudspeaker inside. The experimental results show that developed techniques provide accurate estimation for the acoustically induced vibrations. (C) 1995 Acoustical Society of America.
A 2-D ANALYTIC MODEL FOR THE THRESHOLD-VOLTAGE OF FULLY DEPLETED SHORT GATE-LENGTH SI-SOI MESFETS
(1995-12-01)
HOU, CS
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WU, CY
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
A two zone Green's function solution method is proposed to analytically model the potential distribution in the silicon film of fully depleted SOI MESFET's, in which the exact solution of 2-D Poisson's equation is obtained by using the appropriate boundary conditions, From the derived analytic 2-D potential distribution, the bottom potential in the active silicon film is used to analyze the drain-induced barrier lowering effect and the threshold voltage is defined in terms of minimum channel potential barrier, The results of the developed analytic threshold-voltage model are compared with those of 2-D numerical simulation, and good agreements are obtained for the gate length down to 0.1 mu m with wide ranges of structure parameters and bias conditions.
Influence of As/Al and Sb/Al gas flow ratios on growth of AlAs1-xSbx alloys
(1995-12-01)
Chen, WK
;
Ou, J
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交大名義發表
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電子物理學系
;
National Chiao Tung University
AlAs1-xSbx epilayers were grown on InP (100) substrates using the metalorganic chemical vapor epitaxial growth technique. Experimental results demonstrate that the solid concentration of AlAsSb is more naturally expressed as a function of the input As/Al partial pressure ratio, and not of the V/III ratio or the Sb mole fraction in group V used during the growth. In fact, the AlAs solid concentration and the input partial pressure ratio of As to Al are proportional to each other. According to the phase diagram described above, the controllability of the solid concentration of AlAsSb could be improved.
VLSI cell placement on arbitrarily-shaped rectilinear regions using neural networks with calibration nodes
(1995-12-01)
Chang, RI
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Hsiao, PY
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交大名義發表
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資訊工程學系
;
National Chiao Tung University
In VLSI or PCB layout, one often encounters a region that is either of rectilinear shape or can be approximated by a rectilinear region. Although many placement methods have been proposed, most of them are applicable only to rectangular regions. For these algorithms to be applied to a rectilinear region, two processing steps, region partitioning and rectangular region cell placement are necessary. Hence, the placement results are so far dependent on the locations of the regions partitioned and frequently become trapped in local minima. Recently, neural networks have been suggested as a new way to resolve the cell placement problem. This paper proposed a unified modeling method that uses a neural net model with additional calibration nodes to model rectilinear region cell placement. In this method, the ideal distance between cells is preserved to simultaneously minimize both the total wire length and the module overlap. Unlike traditional approaches, the proposed algorithm requires only a single processing step. Experiments have been conducted to verify the performance of the proposed algorithm. The total wire length obtained by our method is shorter than those generated by previous methods.
Chemical mechanical polishing of PSG and BPSG dielectric films: The effect of phosphorus and boron concentration
(1995-12-01)
Liu, CW
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Dai, BT
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Yeh, CF
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
Chemical-mechanical polishing of blanket and patterned oxide films doped with phosphorus and boron has been studied. FTIR was used to characterize the film microstructure. Experimental results show that an increase of phosphorus level promoted the polish rate of PSG film. We also found that increasing the boron content enhanced the polish rate of BPSG films although phosphorus contents is decreased. This implies that boron is more effective than phosphorus in enhancing the polishing rate of BPSG films. However, the hardness of these doped films is slightly affected by doping level. Excellent planarity achieved by CMP is demonstrated for patterned wafers. Here, we also identify inversion patterns for the composite dielectric formed by a thin hard film on the top of a thick soft film. Such inversion phenomenon can be used for monitoring CMP process as a means of end point detection.
Voltage-controlled optical fiber coupler using a layer of low-refractive-index liquid crystal with positive dielectric anisotropy
(1995-12-01)
Pan, RP
;
Liou, SR
;
Lin, CK
;
交大名義發表
;
電子物理學系
A variable fiber directional coupler is made using liquid crystal as the intermediate cladding layer between two side-polished optical fibers. A nematic liquid crystal with low refractive index and positive dielectric anisotropy is used. An ac electric field is applied to the liquid crystal by applying a voltage across two parallel electrode stripes on the two sides of the fibers. The electric field rotates the molecular orientations and changes the refractive index of the liquid crystal. The coupling ratio between the two fibers is then controlled by the applied voltage. The dependence of the coupling ratio on the applied voltage is studied for various light wavelengths, including a continuous variable range between 1.272 mu m and 1.310 mu m.
A shift register architecture for high-speed data sorting
(1995-12-01)
Lee, CY
;
Tsai, JM
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents a shift-register architecture or SRA, for data sorting applications. The operations performed by the proposed architecture are (1) shift right, (2) shift left, (3) load, and (4) initialize. Sorting operations, such as insert and delete, can be realized by the combination of these 4 basic operations. The architecture is very regular and mainly composed of two basic cells, sort-cell and compare-cell. The latter is designed to generate control signals orchestrating the operation of sort cells which contain the sorted input sequences. Experimental results show that a single chip solution can achieve real-time performance based on 1.2 mu m CMOS double-metal technology.