Browsing by Author "Wang, CK"

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A direct determination technique for azimuth alignment in photoelastic modulation ellipsometry
(1999-12-01)
Chao, YF
;
Wang, CK
;
Liu, S
;
光電工程學系
;
Department of Photonics
Instead of the nulling method, a three-intensity-measurement technique is proposed to determine the azimuth deviation of the polarizer (P), photoelastic modulator (PEM) and analyzer (A) with respect to the specimen surface for ellipsometric measurements. After the initial alignment in a straight-through setup, we adjusted the azimuth of P at 45 degrees to the strain axis of the PEM. Arranging a Polarizer-PEM-Sample-Analyzer ellipsometer by subjecting a specimen at the required incident angle, we measured a set of three DC radiances at the zero point of the zero-order Bessel function. In addition to the azimuth deviation, the ellipsometric parameter can also be determined from the same measurements.
A VLSI architecture design for dual-mode QAM and VSB digital CATV transceiver
(1998-12-01)
Shiue, MT
;
Wang, CK
;
Way, WI
;
電信工程研究所
;
Institute of Communications Engineering
In this paper, a transceiver VLSI architecture is proposed for high speed digital CATV modems, which can perform both the QAM and the VSB transmissions [1], [2]. The proposed architecture of all-digital dual-mode QAM/VSB receiver consists of digital AGC, digital demodulator, fractionally spaced blind equalizer and DFE, digital carrier recovery, and symbol timing recovery. Finite word-length simulation results show that the proposed architecture can achieve an SNR 29 dB for both the 64-QAM mode and 8-VSB mode when the 10 bit ADC input signal SNR is 36 dB, and there are +/-6 kHz of carrier frequency offset, +/- 110 ppm of symbol rate offset, and -82 dBc carrier phase-jitter at 10 kHz away from the nominal carrier frequency.
Calculation of laminar separated flow in symmetric two dimensional diffusers
(1995-12-01)
Tsui, YY
;
Wang, CK
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
This study is concerned with numerical analysis of laminar separated flow in symmetric, two-dimensional, straight-walled diffusers. With Reynolds numbers Re = 56 and 114 and expansion ratios ER = 3 and 4, totally, there are four cases considered. At the low Reynolds number and the low expansion reaction the flow in the diffuser is nearly symmetric to the center line, irrespective of the diffusion angle. As Reynolds number or expansion ratio increases, a large recirculation region forms at one side wall and a small one at the other side. For the case with Re = 114 and ER = 4 the small recirculating flow disappears at small diffusion angles and a third recirculating flow appear in the same side of the small main recirculation region for large diffusion angles. The pressure recovery reaches its peak value somewhere downstream of the reattachment point of the large recirculating flow. The effectiveness of the diffuser deteriorates as the diffusion angle increases, apart from that at Re = 56 the effectiveness increases from theta = 15 to 30 deg. Symmetric flow solutions can be obtained by incorporating a symmetric relaxation method. The pressure recovery is higher for the symmetric flow than that for the asymmetric flow owing to the weaker recirculating strength in the former.
Characterization of electron emission from relaxed InAs quantum dots capped with InGaAs
(2005-07-01)
Chen, JF
;
Hsiao, RS
;
Wang, CK
;
Wang, JS
;
Chi, JY
The effect of strain relaxation in a relaxed InAs quantum dot (QD) capped with InGaAs is investigated by admittance and deep-level transient spectroscopy (DLTS). Strain relaxation markedly increases the emission time in the QD region and extends carrier depletion to the bottom GaAs layer. The experimental data show the presence of relaxation traps in the QD region and the neighboring bottom GaAs.layer. The electron emission from the QD region is governed by a trap located at 0.17-0.21 eV below the QD ground state. The electron-escape process is identified as thermal activation at high temperatures and direct tunneling at low temperatures from the trap. In the bottom GaAs layer near the QD, DLTS reveals a relaxation trap at 0.37-0.41 eV relative to the GaAs conduction band. The energy difference between these two traps is comparable to the QD ground-state energy relative to the GaAs conduction-band edge, suggesting that the two traps may be the same trap which is pinned to the GaAs conduction band. The considerable difference between their properties may result from different atoms surrounding the trap. (c) 2005 American Institute of Physics.
Differential matched filter architecture for spread spectrum communication systems
(1996-08-15)
Lin, WC
;
Liu, KC
;
Wang, CK
;
電信工程研究所
;
Institute of Communications Engineering
The authors present a new digital matched filter architecture: digital differential matched filter (DDMF), that employs novel schemes to reduce the number of multiplications and accumulations (M and A). Theoretical analysis shows that the DDMF saves half of the M and A hardware in comparison with the conventional filter, and maintains identical processing gain. This makes the proposed DDMF more suitable for direct sequence spread spectrum (DSSS) communication systems and low power VLSI implementations.
Differential matched filter architecture for spread spectrum communication systems
(1996-08-15)
Lin, WC
;
Liu, KC
;
Wang, CK
;
電信工程研究所
;
Institute of Communications Engineering
The authors present a new digital matched filter architecture: digital differential matched filter (DDMF), that employs novel schemes to reduce the number of multiplications and accumulations (M and A). Theoretical analysis shows that the DDMF saves half of the M and A hardware in comparison with the conventional filter, and maintains identical processing gain. This makes the proposed DDMF more suitable for direct sequence spread spectrum (DSSS) communication systems and low power VLSI implementations.
Direct determination of azimuth angles in photoelastic modulator system
(1998-06-01)
Chao, YF
;
Wang, CK
;
光電工程學系
;
Department of Photonics
Instead of the nulling method, a high-level intensity technique is proposed to determine the relative azimuth orientation of a photoelastic modulator and an analyzer. In a photoelastic modulating system, one can obtain a DC intensity distribution by varying the phase modulation amplitude at two azimuth angles of the analyzer, which are pi/4 apart from each other. The relative azimuth orientation can be determined by taking the ratio of the slopes of these two intensity distributions around the linear region of the zero point of the zero-order Bessel function. A similar technique is also applicable to wave plates for aligning their optical axes with the system.
Enhanced metalorganic chemical vapor deposition titanium nitride film fabricated using tetrakis-dimethylamino-titanium for barrier metal application in sub-half-micron technology
(1996-08-01)
Wang, CK
;
Liu, LM
;
Liao, M
;
Cheng, HC
;
Lin, MS
Enhanced metalorganic chemical vapor deposition (MOCVD) titanium nitride (TiN:C) film with low resistivity (< 700 mu Omega . cm) has been fabricated by thermal decomposition of tetrakis-dimethylamino-titanium (TDMAT; Ti[N(CH3)(2)](4)) Enhancement is carried out by in-situ N-2 plasma treatment of as-deposited TiN:C film and the enhanced TiN:C film has good stability: less than 4% increase in film resistivity after exposure to air for 24 days. The amount of oxygen absorbed in this enhanced TiN:C film after air exposure, determined by Auger electron spectroscopy (AES) was significantly reduced. This enhanced MOCVD TiN:C film has been successfully applied to sub-half-micron devices. A void-tree tungsten plug (W plug) for sub-half-micron holes can be achieved. Good barrier performance and low contact/via resistance have also been demonstrated.
Enhanced metalorganic chemical vapor deposition titanium nitride film fabricated using tetrakis-dimethylamino-titanium for barrier metal application in sub-half-micron technology
(1996-08-01)
Wang, CK
;
Liu, LM
;
Liao, M
;
Cheng, HC
;
Lin, MS
Enhanced metalorganic chemical vapor deposition (MOCVD) titanium nitride (TiN:C) film with low resistivity (< 700 mu Omega . cm) has been fabricated by thermal decomposition of tetrakis-dimethylamino-titanium (TDMAT; Ti[N(CH3)(2)](4)) Enhancement is carried out by in-situ N-2 plasma treatment of as-deposited TiN:C film and the enhanced TiN:C film has good stability: less than 4% increase in film resistivity after exposure to air for 24 days. The amount of oxygen absorbed in this enhanced TiN:C film after air exposure, determined by Auger electron spectroscopy (AES) was significantly reduced. This enhanced MOCVD TiN:C film has been successfully applied to sub-half-micron devices. A void-tree tungsten plug (W plug) for sub-half-micron holes can be achieved. Good barrier performance and low contact/via resistance have also been demonstrated.
Integrated tungsten chemical mechanical polishing process characterization for via plug interconnection in ultralarge scale integrated circuits
(2002-08-01)
Wang, CK
;
Wu, HS
;
Ou, NT
;
Cheng, HC
;
電子工程學系及電子研究所
One integrated tungsten (W) chemical mechanical polishing (CMP) process characterization with wide production margin is developed for W plug application in sub-quarter micron technology. In this study, it is identified that donut-type function failure and reliability degradation on a designed application specific integrated circuit (ASIC) product vehicle result from an extra oxide layer atop the W plugs. W recess in via holes makes the plugs more vulnerable to oxide layer formation. CMP polish rate uniformity, layout dependence of via holes and queue-time (Q-time) control between WCMP and post-cleaning treatment are key parameters for preventing failure from interfacial oxide layer. Integrated optimization of WCMP process combined with W extrusion by a slight oxide polish immediately after WCMP is proposed to achieve a robust W plug process. Significant yield improvement from 45% to 82% in wafer edge region and 0% failure in three qualification lots in a product reliability test are demonstrated.
Measurement of optical activity using a photoelastic modulator system
(1999-02-01)
Wang, CK
;
Chao, YF
;
光電工程學系
;
Department of Photonics
Adjusting the analyzer at 90 degrees to the strain axis of a photoelastic modulator, one can determine the optical activity by measuring the slope of its DC intensity distribution under various phase modulation amplitudes. This technique was applied to measure the ellipticity of few quartz quarter-wave plates and the optical rotation of an optical active crystal. A multiple reflection enhancement effect in the wave prate was observed and discussed. By considering the photoelastic modulator as an elliptical retarder, we also determined its intrinsic ellipticity and static phase retardation, to increase the accuracy of measurements.
Optimization of PVD Ti/CVD TiN liner for 0.35 mu m tungsten plug technology
(1996)
Wang, CK
;
Liu, LM
;
Liao, DM
;
Smith, DC
;
Danek, M
A novel plasma enhanced CVD TiN process was integrated with high density plasma sputter etch preclean (PCII) and 1:1.5 collimated PVD Ti (c-PVD Ti) process to deposit a Ti/TiN liner for tungsten contact and via plugs. The integrated liner process was optimized for a 0.35 mu m non-salicide CMOS device application. RF power and sputter depth used for contact preclean were the major process Variants affecting the contact resistance, junction leakage and transistor threshold voltage. Low contact resistance was obtained for a c-PVD Ti thickness of similar to 375 Angstrom. Via resistance was significantly lower with c-PVD Ti/CVD TiN liner as compared to only a TiN liner. Contact resistance for c-PVD Ti/c-PVD TIN and c-PVD Ti/CVD TiN liners were comparable while contacts with conventional PVD Ti/TiN liner showed significantly higher values due to poor step coverage. Low junction leakage current was obtained for integrated c-PVD Ti/CVD TiN stack.