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ABSTRACT: Grain growth of Cu interconnects in an ultralow k dielectric was achieved at an elevated anneal temperature of 300 ° C without stress voiding related problems. For this, a TaN metal passivation layer was deposited on the Cu interconnect surface prior to the thermal annealing process, which suppressed void formation within the Cu features during the anneal process and reduced inelastic deformation within the interconnects after cooling down to room temperature. As compared to the conventional anneal process at 100 ° C , the passivation layer enabled further Cu grain growth at elevated temperatures, which then resulted in lower electrical resistance in the Cu interconnects.
Applied Physics Letters 02/2011; · 3.84 Impact Factor
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ABSTRACT: Electromigration results are described for a dual damascene structure with copper metallization and a low-k dielectric material. The failure times follow a 3-parameter lognormal behavior, with a threshold failure time needed to represent the entire failure distribution. We found that the threshold failure time scales differently with current density from the median time to failure, which has significant implications for making reliability predictions. It is shown that the threshold failure time corresponds to damage (presumably voids) nucleation of the electromigration process. The observed current density dependency, along with scanning electron microscopy cross sections of stressed samples and Monte Carlo simulations of failure distributions, suggests that both void nucleation and void growth should be considered for accurate modeling of the electromigration lifetime.
Journal of Applied Physics 06/2010; · 2.17 Impact Factor
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ABSTRACT: Electromigration testing of an interconnect system comprised of copper metallization and a low- k dielectric material gives rise to bimodal lognormal statistics with early and late fails. When separated from one another, we observed failure modes characterized by a three-parameter lognormal distribution and the same threshold failure time. It is shown that the threshold failure time corresponds to damage (presumably voids) nucleation of the electromigration process. The dependence of the threshold failure time and the median time to failure on current density suggests that both void nucleation and void growth need to be considered for accurate modeling of the electromigration lifetime.
Applied Physics Letters 09/2009; · 3.84 Impact Factor
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ABSTRACT: Electromigration results are described for a dual damascene structure with copper metallization and a low-k dielectric material. The failure times follow a bimodal lognormal behavior with early and late failures. Moreover, there is evidence of a threshold failure time such that each failure mode is represented by a 3-parameter lognormal distribution. It is found that the threshold failure time scales differently with current density from the median time to failure, which can be explained by considering two components of the electromigration lifetime: one controlled by void nucleation and the other controlled by void growth.
Reliability Physics Symposium, 2009 IEEE International; 05/2009
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R.G. Filippi,
J.F. McGrath,
T.M. Shaw,
C.E. Murray,
H.S. Rathore,
P.S. McLaughlin,
V. McGahay,
L. Nicholson,
P.-C. Wang,
J.R. Lloyd, [......],
G. Goth,
E. Barth,
G. Biery,
C.R. Davis,
R.A. Wachnik,
R. Goldblatt,
T. Ivers,
A. Swinton,
C. Barile,
J. Aitken
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ABSTRACT: The reliability of a stacked via chain stressed under various thermal cycle conditions is described. The chain consists of Cu Dual Damascene metallization with SiLK (trademark of Dow Chemical) as the organic low-k dielectric. Failure analysis indicates that cracks form in the Cu vias during thermal cycle stress. Due to the presence of two failure modes, the thermal cycle statistical behavior is described by a bimodal lognormal failure distribution. The thermal cycle lifetime exhibits a strong dependence on the temperature range and a rather weak dependence, on the maximum temperature in the cycle. Evidence of a threshold temperature range below which thermal cycle fails should not occur as well as a correlation between the test structure yield and reliability are also reported.
Reliability Physics Symposium Proceedings, 2004. 42nd Annual. 2004 IEEE International; 05/2004
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ABSTRACT: Resistance saturation as a function of current density, stripe length, stripe width, and temperature is investigated for a two-level structure with Ti/AlCu/Ti/TiN stripes and interlevel W stud vias. A simple model based on first principles is presented, which relates the maximum fractional resistance change to the current density and stripe length. Experimental results for stripe lengths of 30, 50, 70, and 100 μm are in good agreement with the model predictions. Estimated void sizes based on the resistance saturation data are consistent with the actual void sizes determined from scanning electron microscopy analysis. A weak temperature dependence is found for 0.33 μm-wide samples in the range 170–250°C, while a strong width dependence is observed between 0.33 and 1.50 μm- wide samples. The width dependence is qualitatively explained in terms of a relaxed bulk modulus that depends on the aspect ratio of the interconnect lines. © 2002 American Institute of Physics.
Journal of Applied Physics 04/2002; 91(9):5787-5795. · 2.17 Impact Factor
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ABSTRACT: The electromigration threshold in copper interconnects is reported in this study. The length-dependent electromigration degradation rate is observed and quantified in the temperature range of 295–400 °C. Based on the Blech electromigration model [I. A. Blech, J. Appl. Phys. 47, 1203 (1976)], a simplified equation is proposed to analyze the experimental data from various combinations of current density and interconnect length, as well as to estimate the electromigration threshold product of current density and line length, (jL)th, at a certain temperature. The resulting (jL)th value appears to be temperature dependent, decreasing with increasing temperature in the tested range between 295 and 400 °C. © 2001 American Institute of Physics.
Applied Physics Letters 06/2001; 78(23):3598-3600. · 3.84 Impact Factor
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ABSTRACT: We demonstrate the electromigration threshold, or the so-called short-length effect, in single-damascene copper interconnects with SiO<sub> 2</sub> dielectrics. With standard electrical lifetime measurements and a simplified equation based on the Blech model, the length-dependent electromigration behavior is studied quantitatively over a temperature range between 295°C and 400°C. It is shown that the electromigration threshold becomes more prominent with decreasing temperature. The applicability of the proposed equation is justified, and the practical aspects of the electromigration threshold in copper technologies are discussed.
Interconnect Technology Conference, 2001. Proceedings of the IEEE 2001 International; 02/2001
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ABSTRACT: Software AGC algorithms for narrowband AM/FM and single-sideband
integrated receivers are described. Computer simulations were conducted
to evaluate the proposed schemes. Results indicate that the AGC performs
well and can easily achieve a 100 dB AGC dynamic range, which is enough
for most communication systems. This software AGC design was then
implemented in the ITT/TI integrated communication, navigation, and
identification avionics integrated radio demonstration breadboard. The
AGC/squelch software was executed by TI's micro vector processor
breadboard and the 1750A data processor breadboards, interfaced with the
zero-IF (intermediate frequency) receiver. The integrated radio concept
was demonstrated by the successful execution of the transmit/receive
function with a USAF AN/ARC-186 radio set
Aerospace and Electronics Conference, 1989. NAECON 1989., Proceedings of the IEEE 1989 National; 06/1989
