Browsing by Author "Chin, YL"

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A fair scheduling algorithm with adaptive compensation in wireless networks
(2001)
Wang, KC
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Chin, YL
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資訊工程學系
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Department of Computer Science
In this paper, we propose a fair scheduling algorithm with adaptive compensation (AC-FQ) for wireless networks, which can achieve fairness as well as graceful QoS degradation. AC-FQ changes a flow's weight according to its queue length. A flow with large (small) queue length means its traffic load is heavy (tight). In this way, AC-FQ can not only adaptively compensate recovered error-prone flows based on its traffic load, but also does not degrade the QoS of other error-free flows. Simulation results show that, without sacrificing throughput (queuing delay), ACFQ has less queuing delay (higher throughput) than CIF-Q, which also adopted a compensation mechanism for real-time (non-real-time) applications. Theoretical analysis of AC-FQ supports that our algorithm has bounds on fairness and throughput.
Effect of aluminum seed layer on the crystallographic texture and electromigration resistance of physical vapor deposited copper interconnect
(2000-12-01)
Chin, YL
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Chiou, BS
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Wu, WF
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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
The effects of an Al underlayer with respect to texture control and electromigration (EM) resistance of Cu films are investigated in this study. The Al underlayer enhances the (111) texture of Cu films and the surface smoothness of the annealed Cu film. The same cubic crystal structure (face-centercd cubic) and small difference of the nearest interatomic distance of the (111) plane between Cu and Al result in the increase of the peak ratio I((111))/I-(200) of Cu films. The thicker the Al film, the more preferred the Cu (111) orientation. The resistivity of the Cu/AI bilayer film, which increases at about 0.2 mu Omega .cm per 1-nm-thick Al underlayer, is smaller than the reported value of single phase Cu(Al) solution. The EM resistance of Cu interconnects is also improved when the Al underlayer is present. The mean time to failure (MTF) of Cu interconnects with a 5-nm-thick Al underlayer is longer by one order of magnitude than that without an Al underlayer at 240 degreesC and 12 MA/cm(2).
Effect of the tantalum barrier layer on the electromigration and stress migration resistance of physical-vapor-deposited copper interconnect
(2002-05-01)
Chin, YL
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Chiou, BS
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Wu, WF
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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
The effects of a Ta barrier layer on electromigration and stress migration of Cu films are investigated. The Ta barrier layer enhances both the (111) texture and the median grain size of the annealed Cu films. At 225degreesC, the electromigration mean time to failure (225degreesC-MTF) of Ta/Cu/Ta multilayer interconnects is about two times longer than that of Cu monolayer interconnects. After 500 thermal cycles, the 225degreesC-MTF of Ta/Cu/Ta multilayer interconnects does not change and is about three times longer than that of Cu monolayer interconnects. The activation energy E-a of electromigration of Ta/Cu/Ta multilayer interconnects is 0.77 eV, which is higher than that of Cu monolayer interconnects (0.65 eV). Since the Ta/Cu/Ta specimen has enhanced crystallographic texture and larger grain size. it has both higher electromigration endurance and thermal stress resistance than Cu. However. the measured MTF is shorter than that predicted by an equation proposed by Vaidya and Sinha [Thin Solid Films 75 (1981) 253]. The shorter MTF and smaller E-a values for the Ta/Cu/Ta multilayer compared to the predicted ones are due to the weak Ta/Cu interface, A lifetime of 100 years is predicted for Ta/Cu/Ta multilayer interconnects with and without 500 thermal cycle stress.
Effects of underlayer dielectric on the thermal characteristics and electromigration resistance of copper interconnect
(2003-12-01)
Chin, YL
;
Chiou, BS
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
The effects of underlayer dielectric on the thermal characteristics and electromigration resistance of copper interconnects are investigated. It is shown that the thermal impedance of metal lines on polyimide is about three times that of metal lines on plasma-enhanced chemical vapor deposition of tetraethylorthosilicate (PETEOS) oxide. The open-circuit failure occurs after 75 s stressing at a current density of 1.4 x 10(7) A/cm(2) for polyimide underlayer specimens due to the high joule heating effect which causes the extreme temperature rise at, interconnects. Hence, decomposition of polyimide occurred which further accelerated the breakdown of interconnects. The thermal impedance is one of the major factors causing the electrical resistance to change during the electromigration (EM) test. The activation energies for electromigration of Cu are 0.87 eV for SiO2/Cu/PI2610 and 0.65 eV for SiO2/Cu/SiO2. After 500 thermal cycles, both the mean time-to-failure (MTF) and activation energy E-a decrease for EM, and lognormal standard deviation increases. At 225degreesC, the MTF of SiO2/Cu/PI2610 is about two times longer than that of SiO2/Cu/SiO2.