Browsing by Issue Date, starting with "2001-11-01"

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Structures and properties of the SiNC films on Si wafer at different deposition stages
(2001-11-01)
Wu, JY
;
Kuo, CT
;
Liu, TL
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The films were deposited on Si wafer by a microwave plasma chemical vapor deposition (MPCVD) system with CH4, N-2, up to 8.3 vol.% HZ and additional Si chips as the sources. The films were examined at different deposition times to explore different growth stages of deposition. Examination indicated the deposition can be roughly divided up to three stages, depending on deposition time and based on their structure and property. In the early deposition stages, the films consist of two layers, i.e. Si-oxide and SiNC layers. The SiNC layer consists essentially of nano-crystals embedded in ternary SiNC amorphous matrix with crystal structure close to SiC. In contrast, in the later stage, the films are further covered by a layer of the binary SiN crystalline phases with crystal structures much closer to alpha -Si3N4 than beta -Si3N4 and tetragonal Si3N4 type structures. The band gaps, as revealed by CL (cathodoluminescence) spectra, are similar to3.88 eV (320 nm) for SiN layer and similar to2.82 eV (440 nm) for SiNC layer. Depending on the deposition conditions, the growth competitions among SiC, Si-N and SiNC crystalline phases may result in different morphologies, compositions and properties of the films. (C) 2001 Elsevier Science B.V All rights reserved.
Successive current-voltage measurements of a thick isolated diamond film
(2001-11-01)
Huang, BR
;
Ke, WC
;
Hsu, JF
;
Chen, WK
;
電子物理學系
Polycrystalline diamond films were deposited on p-type (100) silicon substrate using a methane/hydrogen gas mixture in a microwave plasma-assisted chemical vapor deposition system. After the back-etched process, the Al contacts were evaporated on both sides of a 150 mum thick isolated diamond film for consecutive high-voltage measurements. It was found that the current-voltage (I-V) characteristics of the Al/diamond/Al structure exhibited two Schottky barrier diodes in a back-to-back configuration. Since the top diamond surface possessed better diamond quality than the bottom surface, the top Schottky diode with a breakdown voltage of 897 V and a lower breakdown voltage of -515 V for the bottom Schottky diode was observed for the first I-V measurement. However, the breakdown voltage was decreased by 37 and 140 V for the top and bottom Schottky diodes after the consecutive sixth repeated measurements. It was found that the oxygenated phenomenon was more prominent; in addition, the quality of the isolated diamond film was also degraded after the consecutive high-voltage measurements. It was indicated that decrease of the breakdown voltage was due to the oxidation layer and the non-diamond components on both surfaces of the isolated diamond film. (C) 2001 Elsevier Science B.V. All rights reserved.
Nanostructure patterns written in polycarbonate by a bent optical fiber probe
(2001-11-01)
Chen, SH
;
Chen, YF
;
電子物理學系
;
Department of Electrophysics
An atomic force, microscope operated in tapping mode using a homemade bent optical fiber probe was used to pattern nanometer-scale features. Trenches of different dimensions were written on polycarbonate that was pre-exposed to an excimer laser. Lines with widths varying from 260 to 600 nm and depths ranging from 30 to 120 nm have been made. The present technique as a complementary tool to other lithographic processes has been demonstrated to be potentially suitable for low-cost and high-precision applications. (C) 2001 American Vacuum Society.
Enhancing the resistance of low-k hydrogen silsesquioxane (HSQ) to wet stripper damage
(2001-11-01)
Chang, TC
;
Mor, YS
;
Liu, PT
;
Tsai, TM
;
Chen, CW
The interaction between low-k hydrogen silsesquioxane (HSQ) film and wet stripper was investigated. The wet stripper has been commonly used to remove photoresister in IC integration processing. However, the high content of alkalinity in the stripper solution often leads to the hydrolysis of HSQ film, forming dangling bonds in the HSQ. The dangling bonds in the HSQ film can easily react with hydroxide ion (OH-) in wet stripper solution and form Si-OH bonds. The resultant HSQ film will tend to uptake water and consequently increase both the leakage current and dielectric constant. In this study, H-plasma pre-treatment was applied to the HSQ film. The hydrogen plasma treatment passivates the HSQ surface and prevent HSQ from water uptake during photoresist stripping. Therefore, dielectric degradation can be avoided with the H-2-plasma pre-treatment. (C) 2001 Elsevier Science B.V. All rights reserved.
Characterization of phosphorus-doped and boron-doped diamond-like carbon emitter arrays
(2001-11-01)
Tsai, CL
;
Chen, CF
;
Lin, CL
;
材料科學與工程學系
;
Department of Materials Science and Engineering
We synthesized phosphorus-doped and boron-doped emitters by using trimethylphosphite P(OCH3)(3) and trimethylborate B(OCH3)(3) as doping sources in a microwave plasma chemical vapor deposition system. Based on our experimental results from scanning electron microscopy and Raman spectra, there is much difference among undoped, phosphorus-doped, and boron-doped diamondlike material. In addition, doping both phosphorus and boron can enhance electric properties by reducing the turn-on voltage and can increase the emission current density. The turn-on voltages of undoped, boron-doped, and phosphorus-doped emitters in triode-type field emitter arrays are 15, 8, and 5 V, respectively. The emission currents of boron-doped and phosphorus-doped emitters are about 20 and 80 times larger than the undoped. (C) 2001 American Institute of Physics.
Correlation between defect concentration and carrier lifetime of GaAs grown by molecular beam epitaxy at different temperatures
(2001-11-01)
Lin, GR
;
Liu, TA
;
Pan, CL
;
光電工程學系
;
Department of Photonics
A pump-probe study of GaAs grown by molecular beam epitaxy at low temperatures (LT-GaAs) is performed. Ultrashort carrier lifetimes of the as-grown LT-GaAs increase from <0.13 ps (measurement limitation) to 1.8 +/-0.2 ps as the growth temperature is increased from 200 degreesC to 320 degreesC. The carrier lifetime was found to be approximately inversely proportional to the antisite defect concentration. This trend is found to be in reasonably good agreement with the Schokley-Read-Hall model. The decreasing trend in the amplitudes of continuous-wave and transient reflectivities (DeltaR/R) as a function of the growth temperature for the LT-GaAs is explained as an induced absorption caused by dense arsenic antisite defects. The sign of the transient DeltaR/R reversed for LT-GaAs grown at 200 degreesC. This is tentatively attributed to the band gap renormalization effect.
Properties of Si-C-N films prepared on Si substrate using cobalt interfacial layers
(2001-11-01)
Chang, HL
;
Kuo, CT
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A microwave plasma chemical vapor deposition (MPCVD) process was successfully used to synthesize Si-C-N films. The film properties were tuned by deposition parameters and engineering interfacial Co layers on Si substrates. The films were deposited by using CH4, N-2, and additional solid Si columns as raw material sources. The films were characterized by scanning electron microscopy (SEM) for film morphologies, X-ray photo-emission spectroscopy (XPS) and cathodoluminescence (CL) spectroscopy for bonding structure and band gap analyses. The results show that the application of Co interlayer can have the following effects: (1) it can change film morphology from (100) preferred orientation to become pyramidal structure, and the band gap from 2.93 to 4.00 eV; (2) it may possess the additional Si(2p)-Si bonding in the films. By adding additional Si source, the atomic ratio of Si:C:N can change significantly with the decrease in carbon content of films, the film structure may vary from amorphous to crystalline and possess additional C(1s)=N bonding (or N(1s)=C bonding). In summary, the composition, morphology, bonding and crystal structures of Si-C-N films have been successfully demonstrated to be manipulated through applications of Co interlayer and additional Si source. (C) 2001 Elsevier Science B.V. All rights reserved.
Optimal minimal-order least-squares estimators via the general two-stage Kalman filter
(2001-11-01)
Hsieh, CS
;
Chen, FC
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電控工程研究所
;
Institute of Electrical and Control Engineering
A direct derivation of the optimal minimal-order least-squares estimator (OMOLSE) is presented using the recently developed general two-stage Kalman filter (GTSKF). Using this new result, the reduced-order estimators of O'Reilly and Fairman are readily shown to be equivalent. A practical implementation issue to consider these two estimators is also addressed.
Characterization and reliability of low dielectric constant fluorosilicate glass and silicon rich oxide process for deep sub-micron device application
(2001-11-01)
Cheng, YL
;
Wang, YL
;
Liu, CW
;
Wu, YL
;
Lo, KY
Fluorosilicate Glass (FSG) with low dielectric constant currently has been replaced as an alternative to SiO2 for device speed improvement. However, several integration aspects, such as Fluorine (F) distribution, F thermal stability, gap fill capability, capacitance reduction and via resistance of FSG prepared by the high density plasma (HDP) chemical vapor deposition (CVD) method are of concern for sub-0.18-mum devices. In this study, HDP-FSG films show different F concentrations at different locations on an 8-inch wafer. In addition, the FSG film shows poor thermal stability and F diffuses out of the film after high temperature annealing and the pressure cook test (PCT). However, the thermal stability of FSG film can be improved by capping with an oxide layer. The results indicate that silicon rich oxide (SRO) has a better effect at blocking the F diffusion out of FSG films at high temperature than plasma enhanced oxide (PE-OX). For the gap fill capability, HDP-FSG can fill all 0.23-mum gaps and some of the 0.21-mum gaps with an aspect ratio <3.8 but not the 0.19-mum gaps. A 8000 Angstrom HDP-FSG film with 600 Angstrom USG liner and 2000 Angstrom cap layer shows approximately 7.5 to 7.7% capacitance reduction on 0.23/0.23-mum gaps when compared with USG (undoped silicate glass). In addition, FSG has a larger capacitance reduction on the wider metal lines than the thinner metal lines at the same gap size due to a capacitance fringe effect. The via resistance for 0.26 mum unlanded via (which allow minor photo mis-alignment) of HDP-FSG film is also similar to that of USG. (C) 2001 Elsevier Science B.V. All rights reserved.
A new analysis of direct-sequence pseudonoise code acquisition on Rayleigh fading channels
(2001-11-01)
Sheen, WH
;
Wang, HC
;
電信工程研究所
;
Institute of Communications Engineering
Accurate performance evaluation of direct-sequence pseudonoise code acquisition on Rayleigh fading channels is investigated in this paper. For fading channels the homogeneous Markov chain model, used to characterize the acquisition process over additive white Gaussian noise channels, is no longer valid due to the correlations between cell detections incurred by fading. Hence, the traditional direct and now-graph approaches for performance evaluation of the code acquisition are not applicable to fading channels. In this paper, a new analysis is proposed for accurate evaluation of the acquisition performance on Rayleigh fading channels. The analysis is quite general and can include various search strategies, types of correlators, and test methods with different performance measures: probability mass function and/or moments of acquisition time. Analytical and simulation results show that the new method predicts the acquisition performance very accurately.
Diamond growth onCoSi(2)/Si by bias-enhanced microwave plasma chemical vapor deposition method
(2001-11-01)
Chen, MR
;
Chang, L
;
Chang, DF
;
Chen, HG
;
材料科學與工程學系
Diamond was grown on polycrystalline CoSi2/Si substrates by bias-enhanced microwave plasma chemical vapor deposition. Both of the positive and negative biasing effects were investigated by microstructural characterization. It has been found that nucleation density can reach similar to 10(9) cm(-2) with positive biasing, much higher than with negative biasing. Cross-sectional transmission electron microscopy shows that diamond deposited by positive biasing grows on a relatively smooth CoSi2 surface, while the etching effect of ion bombardment during negative biasing results in a rough CoSi2 surface. The diamond morphology obtained with negative bias has a flat surface with a strong (1 0 0) texture. (C) 2001 Elsevier Science B.V. All rights reserved.
A programmable pipelined digital differential matched filter for DSSS receiver
(2001-11-01)
Chiou, CH
;
Huang, CW
;
Wen, KA
;
Wu, ML
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電子工程學系及電子研究所
A programmable pipelined digital differential matched filter (PDMF) implemented for a direct sequence spread spectrum receiver is proposed in this paper. To reduce the power consumption, the architecture PDMF is based on the synchronization combined PN code phase acquisition algorithm (Huang et al., 1999). Compared with the conventional PN code phase acquisition algorithm, the theoretical analysis result indicates that the PDMF acquires both power efficient and preferable detection. Depending on different applications, programmability allows the PDMF to implement 3-tap, 5-tap, or 11-tap Barker codes with the same hardware but different precisions for each tap coefficient. For short tap Baker codes, the architecture could adopt more precision on each tap coefficient to resist the channel noise. Simulation results also show that there are fewer errors of high sample precision with the same tape.
Impact of interface nature on deep sub-micron Al-plug resistance
(2001-11-01)
Tsui, BY
;
Yang, TJ
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Ku, TK
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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
Sputter clean had been accepted as an effective surface clean process prior to metal deposition. In this work, the impact of interface nature on via resistance of Al-interconnect as via size is scaled down to 0.16 mum was studied. Al-F compound was identified as the main interfacial contaminants after standard post-etch clean process if the TiN laver of the underlying metal line were etched through during via etch. For via size larger than 0.25 mum (aspect ratio lower than 3.2), Al-F compound can be removed by sputter clean effectively. However, below 0.25 mum, sputter clean efficiency decreases such that via resistance is degraded by the existence of Al-F interfacial layer. On the other hand, sputter clean results in oxide re-deposition, which in turn degrades via resistance. It is suggested that to obtain low resistance sub-0.2 mum via, via etch must stop on TiN layer such that no Al-F layer can be formed. Otherwise, new interfacial layer clean technology with high efficiency and without side effect has to be developed. (C) 2001 Elsevier Science Ltd. All rights reserved.
A multicast mechanism for mobile networks
(2001-11-01)
Lin, YB
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資訊工程學系
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Department of Computer Science
This letter proposes a multicast table approach to support GSM/UMTS multicast that minimizes the paging cost. The implementation and execution of the multicast tables are very efficient. The costs for updating these tables can be ignored compared with the costs of standard location update procedures. Furthermore, our mechanism can be implemented within the mobility databases without modifying the standard location update messages. We show that our mechanism always outperforms the existing GSM/UMTS multicast mechanisms.
Video segmentation using a histogram-based fuzzy c-means clustering algorithm
(2001-11-01)
Lo, CC
;
Wang, SJ
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資訊管理與財務金融系註：原資管所+財金所
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Department of Information Management and Finance
The purpose of video segmentation is to segment video sequence into shots where each shot represents a sequence of frames having the same contents, and then select key frames from each shot for indexing. Existing video segmentation methods can be classified into two groups: the shot change detection (SCD) approach for which thresholds have to be pre-assigned, and the clustering approach for which a prior knowledge of the number of clusters is required. In this paper, we propose a video segmentation method using a histogram-based fuzzy c-means (HBFCM) clustering algorithm. This algorithm is a hybrid of the two approaches aforementioned, and is designed to overcome the drawbacks of both approaches. The HBFCM clustering algorithm is composed of three phases: the feature extraction phase, the clustering phase, and the key-frame selection phase. In the first phase, differences between color histogram are extracted as features. In the second phase, the fuzzy c-means (FCM) is used to group features into three clusters: the shot change (SC) cluster, the suspected shot change (SSC) cluster, and the no shot change (NSC) cluster. In the last phase, shot change frames are identified from the SC and the SSC, and then used to segment video sequences into shots. Finally, key frames are selected from each shot. Simulation results indicate that the HBFCM clustering algorithm is robust and applicable to various types of video sequences. (C) 2001 Elsevier Science B.V. All rights reserved.
Diamond nucleation on Cu by using MPCVD with a biasing pretreatment
(2001-11-01)
Chuang, KL
;
Chang, L
;
Lu, CA
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Bias enhanced nucleation of diamond on polycrystalline Cu substrates has been investigated. With CH4 concentration increased, the nucleation density is increased and saturated at 10% CH4, but the quality of diamond is decreased. Bias voltages also play an important role on the nucleation of diamond. It is found that the nucleation density is highest when the voltage was set at -250 V. (C) 2001 Elsevier Science B.V. All rights reserved.
Acoustic echo cancellation using iterative-maximal-length correlation and double-talk detection
(2001-11-01)
Jenq, JC
;
Hsieh, SF
;
電信工程研究所
;
Institute of Communications Engineering
The conventional maximal-length-correlation (MLC) algorithm to estimate room impulse response for adaptive echo cancellation (AEC) is disturbed by both far-end and near-end speeches. In this paper, a new iterative-maximal-length-correlation (IMLC) algorithm is proposed to reduce the far-end speech interference. To avoid the near-end interference, a new double-talk detection (DTD) method is proposed by tracking the squared coefficients errors of the AEC filter. This DTD method has well-separated detection margins among single-talk (ST), double-talk (DT), and echo path changes. Statistical analysis and computer simulations confirm that our proposed IMLC-DTD algorithm outperforms conventional methods.
The effect of ammonia plasma treatment on low-k methyl-hybrido-silsesquioxane against photoresist stripping damage
(2001-11-01)
Chang, TC
;
Mor, YS
;
Liu, PT
;
Tsai, TM
;
Chen, CW
The integration process, low-k hybrid-organic-siloxane-polymers (HOSP) and photoresist stripping process have been investigated. The dielectric properties of HOSP films are degradated after photoresist removal. This is because photoresist stripping processes destroy the functional groups and induce moisture uptake in HOSP films. In this study, NH3-plasma treatment was used for HOSP films to form a thin nitrogen-containing layer, preventing HOSP films from O-2 plasma ashing and chemical wet stripper damage during photoresist removal. The leakage current is decreased significantly and the dielecric constant is maintained at a low value after photoresist removal. These experimental results show that NH, treatment is a promising technique to enhance the resistance of HOSP films to the photoresist stripping process. (C) 2001 Elsevier Science B.V. All rights reserved.
Differences in PM10 concentrations measured by beta-gauge monitor and hi-vol sampler
(2001-11-01)
Chang, CT
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Tsai, CJ
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Lee, CT
;
Chang, SY
;
Cheng, MT
In this paper. differences between the 24-h average PM10 concentrations of Wedding beta -gauge monitor and Andersen or Wedding hi-vol sampler were studied. When the deliquescent point is not exceeded, PM10 concentrations of the beta -gauge are close to those of the manual samplers. The ratio of beta -gauge PM10 to Andersen PM10 and Wedding PM10 is 1.08 +/-0.06 and 1.09 +/-0.12, respectively. However, when the deliquescent point is exceeded, water absorption by the inorganics of aerosols leads to higher PM10 concentrations of the beta -gauge compared to those of the manual sampler. The ratio of beta -gauge PM10 to Andersen PM10 and Wedding PM10 is 1.21 +/-0.22 and 1.27 +/-0.15, respectively. However., due to evaporation of water from the aerosols collected on the filter tape of the beta -gauge, differences in PM10 concentrations are much less than theoretically calculated. (C) 2001 Elsevier Science Ltd. All rights reserved.
Synthesizing crystalline carbon nitrides by using two different bio-molecular materials
(2001-11-01)
Kuo, CT
;
Wu, JY
;
Lu, TR
;
材料科學與工程學系
;
Department of Materials Science and Engineering
It is important to examine the deposition mechanism of crystalline carbon nitrides and to investigate the linkage between bio-molecular and superhard materials. Two different CN compound bio-molecular targets with the sixfold ring structure similar to that in the hypothetical beta -C3N4 were proposed to be used for synthesizing carbon nitride films on different substrates by reactive ion beam sputtering. Effect of the substrate material and the correlation between the bonding characters of the different target materials and the deposited films were examined. The deposited films exhibit no significant differences in the atomic NIC ratio and film properties at the condition of 1000 eV Ar-ion beam, no matter which one of the two target materials and which one of the seven substrate materials are. The XPS and AES analyses reveal that the atomic NIC ratio of the films can go up to 0.50, which is much higher than most of the reported values (0.2-0.35). The FTIR, XPS and Raman spectra clearly indicate the co-existence of chemical bondings of C-N single bond and C=N double bond; and no detectable C dropN triple bonding is observed, which forms a favor basis for further processing of the films to improve the film quality. The XRD, electron diffraction, TEM and AFM analyses indicate that the deposited films may consist of the nano-sized beta -C3N4 crystaflites embedded in matrix of graphite form of C3N4 Structure, and the volume concentrations of the crystalline phases are high enough to be detected by XRD. The implication of the results is that one highly probable way to explore the deposition mechanisms of crystalline carbon nitrides is to manipulate chemical bonding information using different target materials. (C) 2001 Elsevier Science B.V. All rights reserved.