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ABSTRACT: A new accelerated testing scheme for detecting SRAM bit failure caused by random telegraph noise (RTN) is proposed. By repeatedly monitoring the fail bit count (FBC) under a reduced margin operation condition, increasing trend of FBC along time was clearly observed, which is believed to be caused by RTN. In addition, physics-based ultra-fast Monte Carlo RTN simulation program has been developed, which quantitatively reproduces the test results. By using the simulation calibrated by the test, product reliability against RTN can be accurately predicted.
VLSI Technology (VLSIT), 2010 Symposium on; 07/2010
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ABSTRACT: We investigated the thermal characteristics of Cu/low-k interconnects to suppress the impact of Joule heating (JH) on electromigration. The thermal time constants in multilayered Cu/low-k interconnects were experimentally investigated for the first time on the basis of the transient thermal response. Furthermore, we analyzed the use of direct radiation through stacked contact/via to suppress the temperature increase from JH. The impact of JH on the critical product of the current density and the line length was also investigated.
Reliability Physics Symposium (IRPS), 2010 IEEE International; 06/2010
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ABSTRACT: New analysis methods useful for understanding both complex waveforms and statistical behaviors of Random Telegraph Noise (RTN) are proposed. Complex waveforms are clearly visualized using Time Lag Plots. Bias dependence of statistically extracted average trap number is discussed, with emphasis on the importance of undetectable traps on product reliability.
Electron Devices Meeting (IEDM), 2009 IEEE International; 01/2010
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ABSTRACT: Reliability of 32-nm-node ultralow-k (k=2.4)/Cu multilevel interconnects incorporating a bilayer low-k barrier cap (k=3.9) was improved without excessive wiring resistance by using CuAl seed technology with high-temperature and short-time annealing. Though the increase in wiring resistivity was about 10%, both electromigration (EM) and stress-induced voiding (SiV) reliability was clearly improved by using Cu-0.5 wt%Al seed metal.
Electron Devices Meeting (IEDM), 2009 IEEE International; 01/2010
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ABSTRACT: A single-charge-based random fluctuation model suited for analyzing both random telegraph noise (RTN) and intrinsic channel transistors (UTB-SOI, FinFET etc) is proposed. Combining a quantitative formula for the worst case V<sub>TH</sub> shift (DeltaV<sub>TH</sub>) with measured data of RTN amplitude distributions, it is shown that RTN should not be ignored for scaled SRAM design. The model also shows that scaling of intrinsic channel FETs will be limited by the fluctuations caused by residual random charge, which rapidly increase in proportion to 1/LW.
VLSI Technology, 2009 Symposium on; 07/2009
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ABSTRACT: We investigated Joule heating effects on EM in Cu/low-kappa interconnects. The 1-D radiation mainly contributes to Joule heating. The contribution of the 2-D radiation is larger in a smaller area. However, the passive lines in the same layer do not act as a radiation activator but rather as a compounding factor. EM lifetime degradation is remarkable for dense structure due to poor 2-D radiation. High frequency pulse stress reduces Joule heating, and EM lifetime is improved due to reduction of the Joule heating.
Reliability Physics Symposium, 2009 IEEE International; 05/2009
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D. Oshida,
T Takewaki,
M Iguchi,
T. Taiji,
T Morita,
Y Tsuchiya,
H Tsuchiya, S. Yokogawa,
H. Kunishima,
H. Aizawa,
N Okada
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ABSTRACT: We have analyzed the correlation between insulator surface copper contamination and time-dependent dielectric breakdown (TDDB) quantitatively for the first time. TDDB lifetime strongly depends on the copper contamination after CMP process, and it is important to control the redox potential to be less than -0.5 V vs. NHE and to utilize a chelating agent on cleaning sequence. Furthermore, we have successfully optimized the post-CMP sequence to decrease the size of antioxidant-copper complex, and improved the TDDB lifetime.
Interconnect Technology Conference, 2008. IITC 2008. International; 07/2008
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ABSTRACT: In this paper, we investigated the effect of impurity (aluminum; Al) doping on the resistivity of damascene copper (Cu) interconnects by categorizing it into surface, grain-boundary, and impurity-scattering factors by means of a comprehensive scattering model. Segregation of Al dopant atoms to the interface of the lines increases the resistivity through increased surface scattering. Electromigration (EM)-induced Cu drift is suppressed as the Al concentration increases. The EM lifetime is improved by the suppression of Cu diffusion due to the piled-up Al at the top surface of the Cu interconnects.
IEEE Transactions on Device and Materials Reliability 04/2008; · 1.54 Impact Factor
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S. Yokogawa,
K. Kikuta,
H. Tsuchiya,
T. Takewaki,
M. Suzuki,
H. Toyoshima,
Y. Kakuhara,
N. Kawahara,
T. Usami,
K. Ohto,
K. Fujii,
Y. Tsuchiya,
K. Arita,
K. Motoyama,
M. Tohara,
T. Taiji,
T. Kurokawa,
M. Sekine
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ABSTRACT: We investigated tradeoff characteristics between resistivity and reliability for scaled-down Cu-based interconnects. A unique resistivity-measurement technique is proposed to detect influences due to impurity doping. Using this technique, we investigated the impacts of the impurity doping on three types of copper interconnects - cobalt-tungsten-phosphorous (CoWP) metal-cap interconnects, plasma-enhanced chemical-vapor-deposition self-aligned barrier interconnects, and CuAl alloy interconnects - and clarified the tradeoffs between the resistivity and the reliability. We found that the metal-cap interconnect shows not only high reliability but also outstanding efficiency with regard to the suppression of resistance increase due to impurity doping.
IEEE Transactions on Electron Devices 02/2008; · 2.32 Impact Factor
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ABSTRACT: We investigated the impurity (Al) doping effect on resistivity of damascene Cu interconnects with decomposing into surface, grain boundary, and impurity scattering factors by employing comprehensive scattering model. The surface scattering is dominant for resistivity increasing. Electromigration-induced Cu drift is suppressed as Al concentration increases. The electromigration lifetime is improved by suppression of the Cu diffusion due to piled-up Al at the top surface of Cu interconnects.
Reliability physics symposium, 2007. proceedings. 45th annual. ieee international; 05/2007
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S. Yokogawa,
K. Kikuta,
H. Tsuchiya,
T. Takewaki,
M. Suzuki,
H. Toyoshima,
Y. Kakuhara,
N. Kawahara,
T. Usami,
K. Ohto,
K. Fujii,
Y. Tsuchiya,
K. Arita,
K. Motoyama,
M. Tohara,
T. Taiji,
T. Kurokawa,
M. Sekine
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ABSTRACT: A novel resistivity measurement technique has been proposed for scaled-down Cu interconnects viewing the high-reliability automobile applications. This technique enables to detect the interconnect resistivity dependence on impurity concentration, free from dimension dependence. Using this technique, we investigated impacts of impurity concentration on three types of Cu interconnects: 1) CoWP cap; 2) PECVD self-aligned barrier (PSAB); and 3) CuAl interconnects and clarified the tradeoffs between resistivity and reliability. We have found that CoWP cap shows not only high-reliability but also an outstanding efficiency in suppression of resistance increase due to impurity-induced scattering, indicating that it is the most viable candidate for automobile applications in 32nm generation and beyond
Electron Devices Meeting, 2006. IEDM '06. International; 01/2007
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ABSTRACT: Cu interconnects are required for high-performance system-on-a-chip because of their high performance and reliability (Yokogawa et al., 2001) and (Yokogawa, 2004). However, electromigration lifetime decreases with the cross-sectional area of the line (Yokogawa and Tsuchiya, 2005). To improve reliability, Cu-alloys such as CuSn (Tonegawa et al., 2003) and (Lee et al., 1995) and CuAl (Matsubara et al., 2003) were investigated; therefore, the lifetime was increased by a factor of 10. However, the electromigration characteristics and effects of Al doping have not been determined in detail. In this paper, we report the effects of Al doping from seed layer to Cu on electromigration in narrow single damascene lines. The test structure proposed by Kawasaki and Hu (Kawasaki and Hu, 1996) was used to measure the drift velocities accurately. In addition, to investigate the dependencies of Al concentration, the seed layer thickness was changed from 40 to 90nm. The effects of Al doping on incubation time, drift velocity, and critical threshold current density are discussed
Reliability Physics Symposium Proceedings, 2006. 44th Annual., IEEE International; 04/2006
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ABSTRACT: Stress-induced voiding (SIV) was investigated for 130 nm node dual-damascene Cu interconnects. Three SIV failure modes were revealed by TEM analyses. Cumulative failure was investigated at various metal widths, via shape and via position on a metal line at 150°C at which the maximum failure rate was observed. Stress-induced failure at narrow Cu line was also observed, which is associated with tensile stress in Cu calculated by 3D finite element method (FEM) stress analysis. Stress relaxation by dielectric structure and quenching process were demonstrated based on stress simulation, thus the resulting SIV failure was suppressed.
Interconnect Technology Conference, 2003. Proceedings of the IEEE 2003 International; 07/2003
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N. Oda,
S. Ito,
T. Takewaki,
H. Kunishima,
N. Hironaga,
I. Honma,
H. Namba, S. Yokogawa,
T. Goto,
T. Usami,
K. Ohto,
A. Kubo,
H. Aoki,
M. Suzuki,
Y. Yamamoto,
S. Watanabe,
T. Takeda,
K. Yamada,
M. Kosaka,
T. Horiuchi
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ABSTRACT: A robust embedded ladder-oxide (k=2.9)/Cu multilevel interconnect is demonstrated for the 0.13 μm CMOS generation. A stable ladder-oxide IMD is integrated into the Cu metallization with minimum wiring pitch of 0.34 μm, and a single damascene (S/D) Cu-plug structure is applied. An 18% reduction in wiring capacitance is obtained compared with SiO<sub>2</sub> IMD. The stress-migration lifetime of vias on wide metals for S/D Cu-plug structure is much longer than for dual damascene (D/D). The reliability test results such as those for electromigration (EM), Cu interconnect TDDB, and pressure cooker test (PCT) are quite acceptable. Moreover, high flexibility in thermal design and packaging is obtained.
VLSI Technology, 2002. Digest of Technical Papers. 2002 Symposium on; 02/2002
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Microelectronics Reliability. 01/2001; 41:1409-1416.
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Microelectronics Reliability 01/2001; 41:1409-1416. · 1.17 Impact Factor
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M. Iguchi,
T. Takewaki,
Y. Matsubara,
Y. Kunimune,
N. Ito,
Y. Tsuchiya,
T. Matsui,
K. Fujii,
K. Motoyama,
K. Sugai, [......],
K. Nakabeppu,
S. Yamasaki, S. Yokogawa,
Y. Yamamoto,
T. Kunugi,
S. Nakata,
M. Kagamihara,
A. Shida,
S. Nakamoto,
H. Gomi
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ABSTRACT: A high performance 0.15-μm CMOS logic device has been developed
with full-0.56 μm pitch 3-level copper (Cu) interconnects. The
multi-level interconnect system consists of Cu single-damascene wiring
in combination with a borderless W plug at a high aspect ratio of 3.0. A
two-step Cu CMP method suppresses new wiring failures which are Cu ball
generated from Cu polishing dross and side wall damage. A Cu spike into
the W plug is prevented by optimizing the W plug formation process. The
0.28-μm wide Cu wiring with a borderless W plug has advantages over
Al-Cu wiring for electromigration (EM) reliability. We achieve a 23%
reduction of RC delay of a ring oscillator with a loaded wiring length
of 1.5 mm by reducing the wiring thickness by 300 nm
Electron Devices Meeting, 1999. IEDM Technical Digest. International; 02/1999
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ABSTRACT: A novel method for the prediction of early failure (EF) due to a non-visual defect is proposed for the time-dependent dielectric breakdown (TDDB) of low-k dielectrics. The yield-reliability relation model is modified to evaluate the EFs. The effectiveness of the novel method is experimentally confirmed by using a 65 nm technology node. A bimodal lifetime distribution is used to evaluate the lifetime distribution. The probability of EF can be estimated based on the basis of the results and the defect density of each wafer.
Reliability Physics Symposium, 2008. IRPS 2008. IEEE International;
