UCLA-Materials Science Electronic Thin Film Lab at UCLA
 
 




























 
 
TOPICS:


 

2016 Publications
  1. Andriy M. Gusak, Chih Chen, and K. N. Tu, "Flux-driven cellular precipitation in open system to form porous Cu3Sn," Phil. Mag. DOI: 10.1080/14786435.2016.1162913.
  2. Jie-An Lin, Chung-Kuang Lin, Chne-Min Liu, Yi-Sa Huang, Chih Chen, David T. Chu and K. N. Tu, "Formation mechanism of porous intermetallic compound by high current stressing at high temperature in low bump height solder joints," Crystals, 6, 12 (2016).
  3. Yingxia Liu, Yi-Ting Chen, Sam Gu, Dong-Wook Kim, and K. N. Tu, "Fracture reliability concern of (Au,Ni)Sn4 phase in 3D IC microbumps using ENIG surface finishing," Scripta Mat., 119, 9-12 (2016).
  4. Yingxia Liu, Ying-Ching Chu, and K. N. Tu, "Scaling effect of interfacial reaction on intermetallic compound formation in Sn/Cu pillar down to 1 um diameter", Acta Mat, 117, 146 (2016).
  5. Yuan-Wei Chang, Yin Cheng, Feng Xu, Lukas Helfen, Tian Tian, Macro de Michael, Chih Chen, K. N. Tu, and Tilo Bambauch, "Study of electromigration inducing discrete voids formation in flip-chip solder joints by laminography observation and finite-element modeling," Acta Mat, 117, 100-110 (2016).
  6. Hongti Zhang, Jerry Tersoff, Shang Xu, Huixin Chen, Qiaobao Zhang, Kaili Zhang, Yong Yang, Chun-Sing Lee, K. N. Tu, Ju Li, and Yang Lu, "Approaching the ideal elastic strain limit in silicon nanowires," Science Advances, vol. 2, No. 8, e1501382 (2016).
  7. Menglu Li, D. W. Kim, S. Gu, and K. N. Tu, "Joule heating induced thermomigration failure in un-powered microbumps due to thermal crosstalk in 2.5D IC technology," J. Appl. Phys., 120, 075105 (2016).
  8. K. N. Tu, Yingxia Liu, and Menglu Li, "Effect of Joule heating and current crowding on electromigration in mobile technology," Appl. Phys. Rev. (invited and submitted).


 

2015 Publications
  1. K. N. Chen and K. N. Tu, "Materials challenges in three-dimensional integrated circuits," MRS Bulletin, 40, 219-222 (2015).
  2. Yingxia Liu, N. Tamura, Dong Wook Kim, Sam Gu, and K. N. Tu, "A metastable phase of Sn in 3D IC solder microbumps," Scripta Mat., 102, 39-42 (2015).
  3. C. M. Liu, H. W. Lin, Y. S. Huang, Y. C. Chu, C. Chen, D. R. Lyu, K. N. Chen, and K. N. Tu, "Low-temperature direct copper-to-copper bonding enabled by creep on (111) surfaces of nanotwinned Cu," Scientific Reports, 5, 9734 (2015).
  4. Yi-Chia Chou, Wei Tang, Chien-Jyun Chiou, Kai Chen, Andrew Minor, and K. N. Tu, "Effect of elastic strain fluctuation on atomic layer growth of epitaxial silicide in Si nanowires by point contact reactions", Nano Lett., 15, 4121-4128 (2015).
  5. Yingxia Liu, Menglu Li, Dong Wook Kim, Sam Gu, and K. N. Tu, "Synergistic effect of electromigration and Joule heating on system level weak-link failure in 2.5D integrated circuits," J. Appl. Phys., 118, 135304 (2015).
  6. Yaodong Wang, Igor M. De Rosa, and K. N. Tu, "Size Effect on Ductile-to-Brittle Transition in Cu-solder-Cu Micro-joints," IEEE ECTC Proceedings, p. 632-639 (2105). [This paper has been awarded as Intel best student paper.]
  7. Yingxia Liu, Nobumichi Tamura, Dong Wook Kim, Sam Gu, and K. N. Tu, "Effect of Au/Pd Surface Finishing on Metastable Sn Phase Formation in Microbumps," IEEE ECTC Proceedings, p. 810-815 (2015).


 

2014 Publications
  1. K. N. Tu and Wei Tang, "Metallurgical microstructure control in metal-silicon reactions," Science China - Technological Sciences, 57, 505-519 (2014).
  2. Chien-Min Liu, Han-wen Lin, Yi-Chang Chu, Chih Chen, Dian-Rong Lyn, Kuan-Neng Chen and K. N. Tu, "low temperature direct copper-to-copper bonding enabled by creep on highly (111)-oriented Cu surfaces," Scripta Mat., 78-79, 65-68 (2014).
  3. Tze-Bib Song, Yu Chen, Choong-Heui Chung, Yang (Michael) Yang, Brion Bob, Hsin-Sheng Duan, Gang Li, K. N. Tu, Yu Huang, and Yang Yang, "Nanoscale joule heating and electromigration enhanced ripening of silver nanowire contacts," ACS Nano, 8, 2804-2811 (2014).
  4. King-Ning Tu and Andriy M. Gusak, "Kinetics in Nanoscale Materials," 296 pages, Wiley, New York, 2014. ISBN: 978-0-470-88140-8.
  5. Zhang Liang and K. N. Tu, "Structure and properties of lead-free solders bearing micro and nano particles." Materials Science & Engineering: R: Reports, 82, 1-32 (2014).


 

2013 Publications
  1. K. N. Tu, Hsiang-Yao Hsiao, and Chih Chen, "Transition from flip chip solder joint to 3D IC microbump: Its effect on microstructure anisotropy," Microelectronics Reliability, 53, 2-6 (2013).
  2. Y. C. Liang, H. W. Lin, H. P. Chen, C. Chen, K. N. Tu, and Y. S. Lai, "Anisotropic grain growth and crak propagation in eutectic microstructure under cyclic temperature annealing in flip chip SnPb composite solder joints," Scripta Mat., 69, 25-28 (2013).
  3. Han-Wen Lin, Jia-Ling Lu, Chen-Min Liu, Chih Chen, Delphic Chen, Jui-Chao Kuo , and K. N. Tu, "Microstructure control of uni-directional growth of ?-Cu6Sn5 in microbumps on <111> oriented and nanotwinned Cu" Acta Mat., (in press).
  4. K. N. Tu and Tian Tian, "Metallurgical challenges in microelectronic 3D IC packaging technology for future consumer electronic products," Science China - Technological Sciences, 56, No. 7, 1-9 (2013).
  5. G. M. Wu, Y. S. Lin, and K. N. Tu, "Ion beam surface modification of GaN films for high efficient light emitting diodes," Acta Physica Polonica A, 123, 6 (2013).
  6. Shadi A. Dayeh, Wei Tang , Francesca Boioli, Karen L. Kavanagh, He Zheng , Jian Wang, Nathan H. Mack, Greg Swadener, Jian Yu Huang , Leo Miglio, K. N. Tu, and S. Tom Picraux, "Direct Measurement of Coherency Limits for Strain Relaxation in Heteroepitaxial Core/Shell Nanowires," Nano Letters, 13, 1869-1876 (2013).
  7. Wei Tang, S. Tom Picraux, Andriy Gusak, Jian Yu Huang, K. N. Tu, and Shadi Dayeh, "Nucleation and Atomic Layer Reaction in Nickel Silicide for Defect-engineered Si Nanochannels" Nano Lett., 13, 2748-2753 (2013).
  8. Wei Tang, S. Tom Picraux, Jian Yu Huang, Xiaohua Liu, K. N. Tu, and Shadi A. Dayeh, "Gold catalyzed nickel disilicide formation: A new solid-liquid-solid phase growth mechanism," Nano Lett., on line.
  9. Yu Huang and K. N. Tu, edited, "Silicon and Silicide Nanowires; Applications, Fabrication, and Properties", 466 pages, Pan Stanford Publishing, Singapore (2013).
  10. Yi-Chia Chou, Kuo-Chag Lu, and K. N. Tu, "Formation of epitaxial silicide in silicon nanowires," Chapter 5 in "Silicon and Silicide Nanowires" edited by Yu. Huang and K. N. Tu, Pan Stanford Publishing, Singapore (2013). pp. 187 – 235.


 

2012 Publications
  1. Jung Kyu Han, Daechul Choi, Masaru Fujiyoshi, Nobuhiko Chiwata, and K. N. Tu, "Current density redistribution from no current crowding to current crowding in Pb-free solder joints with an extremely thick Cu layer," Acta Mat 60, 102-111 (2012)
  2. Y.S. Huang, Hsiang-Yao Hsiao, Chih Chen, and K.N. Tu, "The effect of a concentration gradient on interfacial reactions in microbumps of Ni/SnAg/Cu during liquid-state soldering", Scripta Materialia 66, 741-744 (2012)
  3. G. M. Wu, K. N. Tu, C. C. Kuo, "Engineering design of high quality GaN epitaxy on silicon substrate using varying GaN/AlGaN composite buffer structures," Rare Metal Mat. Eng, 41(S1), (2012)
  4. Hsiang-Yao Hsiao, Chien-Min Liu, Han-wen Lin, Tao-Chi Liu, Chia-Ling Lu, Yi-Sa Huang, Chih Chen, and K. N. Tu, "Unidirectional Growth of Microbumps on (111)-Oriented and Nanotwinned Copper," Science, 336, 1007-1010 (2012).
  5. Tian, T., Tu, K. N., Chen, H.-Y., Hsiao, H.-Y. and Chen, C. (2012) Thermomigration in SnPb and Pb-Free Flip-Chip Solder Joints, in Lead-Free Solders: Materials Reliability for Electronics (ed K. N. Subramanian), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9781119966203.ch17
  6. Chen, C., Liang, S.-W., Chang, Y.-W., Hsiao, H.-Y., Han, J. K. and Tu, K. N. (2012) Electromigration in Pb-Free Solder Joints in Electronic Packaging, in Lead-Free Solders: Materials Reliability for Electronics (ed K. N. Subramanian), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9781119966203.ch15


 

2011 Publications
  1. Yi-Chia Chou, Wen-Wei Wu, Chung-Yang Lee, L. J. Chen, and K. N. Tu, "Heterogeneous and homogeneous nucleation of epitaxial NiSi2 in [110] Si nanowires," J. Phys. Chem. C, 115, 397-401 (2011).
  2. K. N. Tu, "Reliability challenges in 3D IC packaging technology," Microelectronics Reliability, 51, 517-523 (2011).
  3. A. M. Gusak, A. O. Kovalchuk, and K. N. Tu, "Diffusion in point contact reaction," Defect and Diffusion Forum, Vol. 309-310, pp. 143-148 (2011).
  4. A. M. Gusak, N. V. Tyutyunyk, and K. N. Tu, "Models of interdiffusion in a polycrystalline alloy: Kirkendall effect versus non-equilibrium vacancies and back-stress," Defect and Diffusion Forum, Vol. 309-310, pp. 135-142 (2011).
  5. J. O. Suh, K. N. Tu, Albert T. Wu, and N. Tamura, "Preferred orientation relationships with large misfit interfaces between Ni3Sn4 and Ni in reactive wetting of eutectic SnPb on Ni," J. Appl. Phys. 109, 123513 (2011).
  6. Kuo-Chang Lu, Wen-Wei Wu, Hao Ouyang, Yung-Chen Lin, Yu Huang, Chun-Wen Wang; Zheng-Wei Wu, Chun-Wei Huang; Lih-Juann Chen, and K. N. Tu, "The Influence of Surface Oxide on the Growth of Metal/Semiconductor Nanowires," Nano Lett., 2011, 11 (7), pp 2753-2758.
  7. Yu-Min Lin, Chau-Jie Juang, John H. Lau, Tai-Hong Chen, Robert Lo, M. Kao, Tian Tian, and K. N. Tu, "Electromigration in Ni-Sn intermetallic micro bump joint for 3D IC chip stacking," 2011 IEEE ECTC Proceedings, 351-357 (2011).
  8. Tian Tian, Kai Chen, A. A. MacDowell, Dula Parkinson, Yi-Shao Lai, and K. N. Tu, "Quantitative x-ray microtomography study of 3D void growth induced by electromigration in eutectic SnPb flip-chip solder joints," Script Mat. 65, 646-649 (2011).
  9. Tian Tian, Feng Xu, Jung Kyu Han, Daechul Choi, Yin Cheng, Luksa Helfen, Marco Di Michiel, Tilo Baumbach, and K. N. Tu, "Rapid diagnosis of electromigration induced failure time of Pb-free flip chip solder joints by high resolution synchrotron radiation laminography," Appl. Phys. Lett., 99, 082114 (2011).
  10. Jung Kyu Han, Daechul Choi, Masaru Fujiyoshi, Nobuhiko Chiwata, and K. N. Tu,"Current density redistribution from no current crowding to current crowding in Pb-free solder joints with an extremely thick Cu layer," Acta Mat 60, 102-111 (2012).


 

2010 Publications
  1. Kai Chen, N. Tamura, Wei Tang, M. Kunz, Yi-Chia Chou, K. N. Tu, and Yi-Shao Lai, "High precision thermal stress study on flip chips by synchrotron polychromatic X-ray microdiffraction," J. App. Phys., 107, 063502 (2010).
  2. S. W. Liang, Chih Chen, J. K. Han, Luhua Xu, K. N. Tu, and Yi-Shao Lai, "Blocking hillock and whisker growth by intermetallic compound formation in Sn-0.7Cu flip chip solder joints under electromgiration," J. Appl. Phys. 107,093715 (2010).
  3. Zhengzheng Chen, Nicholas Kioussis, K. N. Tu, Nasr Ghoniem, and Jenn-Ming Yang, "Inhibiting adatom diffusion through surface alloying," Phys. Rev. Lett., 105, 015703 (2010).
  4. Chih Chen, H. M. Tong, and K. N. Tu, "Electromigration and thermomigraion in Pb-free flip chip solder joints," Annu. Rev. Mater. Res. 2010. 40:531-555.
  5. W. W. Wu, K. C. Lu, C. W. Wang, H. Y. Hsieh, S. Y. Chen, Y. C. Chou, S. Y. Yu, L. J. Chen, and K. N. Tu, "Growth of multiple metal/semiconductor nanoheterostructures through point and line contact reactions," Nano Lett., 2010, 10 (10), pp 3984-3989.
  6. K. N. Tu, "Electronic Thin-Film Reliability," 395 pages, Cambridge University Press, UK, available in November 2010 (a text book).
  7. Xiao-Ning Guo, Ru-Jing Shang, Dong-Hua Wang, Guo-Qiang Jin, and Xiang-Yun Guo, and K. N. Tu, "Avoiding loss of catalytic activity of Pd nanoparticles partially embedded in nanoditches in SiC nanowires," Nanoscale Res Lett. 5:332-337 (2010).
  8. Kuan-Chia Chen, Wen-Wei Wu, Chien-Neng Liao, Lih-Juann Chen, and K. N. Tu, "Stability of nanoscale twins in copper under electric current stressing," J. of Appl. Phys., 108, 066103 (2010).
  9. Yi-Chia Chou, Kuo-Chang Lu, and K. N. Tu, "Nucleation and growth of epitaxial silicide in silicon nanowires," Materials Science and Engineering: R: Reports, Vol. 70, pp. 112-125 (2010).
  10. Yi-Chia Chou, Wen-Wei Wu, Chung-Yang Lee, L. J. Chen, and K. N. Tu, "Heterogeneous and homogeneous nucleation of epitaxial NiSi2 in [110] Si nanowires," J. Phys. Chem. C, 2011, 115 (2), pp 397-401.
  11. A. O. Kovalchuk, A. M. Gusak, and K. N. Tu, "Theory of repeating nucleation in point contact reactions between nanowires," Nano Letters, vol. 10, issue 12, pp. 4799-4806.


 

2009 Publications
  1. Di Xu, Vinay Sriram, Vidvuds Ozolins, Jenn-Ming Yang, K. N. Tu, Gery R. Stafford, and Carlos Beauchamp, "In situ measurements of stress evolution for nanotwin formation during pulse electrodeposition of copper", J. Appl. Phys., 105, 023521 (2009)
  2. Yi-Shao Lai, Ho-Ming Tong, and K. N. Tu, edited a special section on "Recent Research Advances in Pb-Free Solders," Microelectronics Reliability, vol. 49, pp. 221-322 (2009)
  3. A. M. Gusak and K. N. Tu, "Interaction between Kirkendall effect and inverse Kirkendall effect in nanoscale particles," Acta Mat., 57, 3367-3373 (2009).
  4. Y. C. Chou, W. W. Wu, L. J. Chen, and K. N. Tu, "Homogeneous nucleation of epitaxial CoSi2 and NiSi in Si nanowires," Nano Lett., 9, 2337-2342 (2009).
  5. C. N. Liao, K. C. Chen, W. W. Wu, L. J. Chen, and K. N. Tu, "In-situ TEM study of electromigration in Cu lines," in "Stress-induced Phenomena in Metallization" ed. by P. S. Ho, S. Ogawa, and E. Zschech, AIP Conference Proceedings, Vol. 1143, Melville, New York (2009).
  6. K. Chen, R. Tamura, M. Kunz, K. N. Tu, and Yi-Shao Lai, "In situ measurement of electromigration-induced transient stress in Pb-free Sn-Cu solder joints by synchrotron radiation based X-ray polychromatic microdiffraction, " J. Appl. Phys., 106, 023502 (2009).
  7. Tian Tian, and K. N. Tu, "Thermomigration in flip chip solder joints," ASE Technology Journal, Vol. 2, No. 2, 132-136 (2009).


 

2008 Publications
  1. J. O. Suh, K. N. Tu, G. V. Lutsenko and A. M. Gusak, "Size distribution and morphology of Cu6Sn5 scallops in wetting reaction between molten solder and copper," Acta Mat., 56, 1075-1083 (2008).
  2. Yung-Chen Lin, Kuo-Chang Lu, Wen-Wei Wu, Jingwei Bai, Lih J. Chen, K. N. Tu, and Yu Huang, "Single crystalline PtSi nanowires, PtSi/Si/PtSi nanowire heterostructures, and nanodevices," Nano Letters 8, 913-918 (2008).
  3. Yuhaun Xu, Shengquen Ou, K. N. Tu, Kejun Zeng, and Rajiv Dunne, "Measurement of impact toughness of eutectic SnPb and SnAgCu solder joints in ball grid array by mini-impact tester", J. Mater. Res., 23, 1482-1487 (2008).
  4. Dong-Hua Wang, Di Xu, Qing Wang, Ya-Juan Hao, Guo-Qiang Jin, Xiang-Yun Guo, and K. N. Tu, "Periodically twinned SiC nanowires", Nanotechnology, 19, 215602 (2008).
  5. Michael Tong, David Sturgess, K. N. Tu, and Jenn-Ming Yang, "Solder joints fabricated by explosively reacting nanolayers," Appl. Phys. Lett. 92, 144101 (2008).
  6. Kai Chen, N. Tamura, B. C. Valek, and K. N. Tu, "Plastic deformation in Al (Cu) interconnects stressed by electromigration and studied by synchrotron polychromatic X-ray microdiffraction," J. Appl. Phys., 104, 013513 (2008).
  7. S. W. Liang, Y. W. Chang, Chih Chen, Jackie Preciado, and K. N. Tu, "Effect of Migration and Condensation of Pre-existing Voids on Increase in Bump Resistance of Flip Chips on Flexible Substrates during Electromigration" J. of Electronic Materials, 37, 962-967 (2008).
  8. Yi-Chia Chou, Wen-Wei Wu, Shao-Liang Cheng, Bong-Young Yoo and Nosang Myung, Lih J. Chen and K. N. Tu, "In situ TEM observation of repeating events of nucleation in epitaxial growth of nano CoSi2 in nanowires of Si," Nano Letters, 8, 2194-2199 (2008).
  9. Kuen-Chia Chen, Wen-Wei Wu, Chien-Neng Liao, L. J. Chen, and K. N. Tu, "Observation of atomic diffusion at twin-modified grain boundaries in Copper," Science, vol. 231, 1066-1069 (2008).
  10. Luhua Xu, Jung-Kyu Han, Jarrett Jun Liang, K. N. Tu, and Yi-Shao Lai, "Electromigration induced high fraction of compound formation in SnAgCu flip chip solder joints with copper column,"Appl. Phys. Lett., 92, 262104 (2008).
  11. Debbie Yang, Y. C. Chan, and K. N. Tu, "The time-dependent melting of flip chip solder joints under current stressing," Appl. Phys. Lett., 93, 041907 (2008).
  12. Hsiao-Yun Chen, Chih Chen, and K. N. Tu, "Failure induced by thermomigration of interstitial Cu in Pb-free flip chip solder joints, " Appl. Phys. Lett., 93, 122103 (2008).
  13. Di Xu, Vinay Sriram, Vidvuds Ozolin, Jenn-Ming Yang, K. N. Tu, Gery R. Stafford, Carlos Beauchamp, Inka Zienert, Holm Geisler, Petra Hofmann, and Ehrenfried Zschech, "Nanotwin formation and its properties and effect on reliability of copper interconnects," Microelectronic Engineering, 85, 2155-2158 (2008).
  14. Luhua Xu, Di Xu, K. N. Tu, Yuan Cai, Ning Wang, Pradeep Dixit, John H. L. Pang, and Jianmin Miao, "Structure and migration of (112) step on (111) twin boundaries in nanocrystalline copper," J. Appl. Phys., 104, 113717 (2008)


 

2007 Publications
  1. Zhenghao Gan, A. M. Gusak, W. Shao, Zhong Chen, S. G. Mhaisalkar, T. Zaporozhets, and K. N. Tu, "Analytical modeling of reservoir effect on electomigration in Cu interconnects," J. Mater. Res., 22, 152-156 (2007).
  2. Luhua Xu, Pradeep Dixit, Jianmin Miao, John H. L. Pang, Xi Zhang, and K. N. Tu, "Through-wafer electroplated copper interconnect with ultrafine grains and high density of nanotwins," Appl. Phys. Lett., 90, 033111 (2007).
  3. Chengkun Xu, Xi Zhang, K. N. Tu, and Y. H. Xie, "Nickel displacement deposition of porous silicon with ultrahigh aspect ratio," J. of Electrochemical Society, 154(3), D170-D174 (2007).
  4. K. N. Tu, Chin Chen, and Albert T. Wu, "Stress analysis of spontaneous Sn whisker growth," J. Mater. Sci: Mater. Electron., 18, 269-281 (2007).
  5. W. Shao, S. G. Mhaisalkar, T. Sritharan, A. V. Vairagar, H. J. Engelmann, O. Aubel, E. Zschech, A. M. Gusak, and K. N. Tu, "Direct evidence of Cu/cap/liner edge being the dominant electromigration path in dual damascene Cu interconnects," Appl. Phys. Lett., 90, 052106 (2007).
  6. Xi Zhang, Zhong Chen, and K. N. Tu, "Immersion nickel deposition on blank silicon in aqueous solution containing ammonium fluoride", Thin Solid Films, 515, 4696-4701 (2007).
  7. Jae-Woong Nah, Kai Chen, K. N. Tu, Bor-Rung Su, and Chih Chen, "Mechanism of electromigration-induced failure in flip chip solder joints with a 10 micron thick Cu under-bump-metallization", J. Mater. Res., 22, 763-769 (2007).
  8. Chengkun Xu, Mingheng Li, Xi Zhang, K. N. Tu, and Y. H. Xie, "Theoretical studies of displacement deposition of Ni into porous Si with ultrahigh aspect ratio", Electrochimica Acta, 52, 3901-3909 (2007).
  9. J. W. Jang, J. K. Lin, D. R. Frear, T. Y. Lee, and K. N. Tu, "Ripening-assisted void formation in the matrix of Pb-free solder joints during solid-state aging," J. Mater. Res., 22, 826-830 (2007).
  10. Fan-Yi Ouyang, K. N. Tu, Chin-Li Kao, and Yi-Shao Lai, "Effect of electromigration in the anode Al interconnect on melting of flip chip solder joints," Appl. Phys. Lett., 90, 211914 (2007).
  11. Kuo-Chang Lu, K. N. Tu, W. W. Wu, L. J. Chen, Bong-Young Yoo, and Nosang V. Myung, "Point contact reactions between Ni and Si nanowires and reactive epitaxial growth of axial nano-NiSi/Si," Appl. Phys. Lett., 90 253111 (2007).
  12. Kuo-Chang Lu, Wen-Wei Wu, Han-Wei Wu, Carey M. Tanner, Jane P. Chang, Lih J. Chen, and K. N. Tu, "In-situ control of atomic-scale Si layer with huge strain in the nano-heterostructure NiSi/Si/NiSi through point contact reaction," Nano Letters, Vol. 7, No. 8, p. 2389-2394, (2007).
  13. Jong-ook Suh, K. N. Tu, and N. Tamura, "Dramatic morphological change of scallop-type Cu6Sn5 formed on (001) single crystal copper in reaction between molten SnPb solder and Cu," Appl. Phys. Lett., 91, 051907 (2007).
  14. K. N. Tu, "Solder Joint Technology: Materials, properties, and reliability", 368 pages, Springer, 2007.? ISBN - 13: 978-0-387-38890-8
  15. Dan Yang, B. Y. Wu, Y. C. Chan and K. N. Tu, "Microstructural evolution and atomic transport by thermomigration in eutectic SnPb flip chip solder joints," J. Appl. Phys. 102, 043502 (2007).
  16. J. O. Suh, K. N. Tu, and N. Tamura, "Preferred orientation relationship between Cu6Sn5 scallops-type grains and Cu substrate in reactions between molten Sn-based solders and Cu," J. Appl. Phys., 102, 063511 (2007).
  17. Xi Zhang, K. N. Tu, Zhong Chen, Y. K. Tan, C. C. Wong, S. G. Mhaisalkar, X. M. Li, C. H. Tung, and C. K. Cheng, "Pulse Electroplating of Copper Film: A Study of Process and Microstructure, "Journal of Nanoscience and Nanotechnology, Vol.8, No.3,1-7 (2007).
  18. Fan-Yi Ouyang, Kai Chen, K. N. Tu, and Yi-Shao Lai, "Effect of current crowding on whisker growth at the anode in flip chip solder joints,"Appl. Phys. Lett., 91, 231919 (2007).
  19. Di Xu, Wei Lek Kwan, Kai Chen, Xi Zhang, Vidvuds Ozolins, and K. N. Tu, "Nanotwin formation in copper thin films by stress/strain relaxation in pulse electrodeposition," Appl. Phys. Lett., 91, 254105 (2007).
  20. L. L. Zhao, N. Li, A. Langner, M. Steinhart, T. Y. Tan, E. Pippel, H. Hofmeister, K. N. Tu, and U. Goesele, "Crystallization of amorphous SiO2 microtubes catalyzed by lithium,"Advanced Functional Materials, 17, 1952-1957 (2007).


 

2006 Publications
  1. A. M. Gusak, G. V. Lutsenko, and K. N. Tu, "Ostwald ripening with non-equilibrium vacancies," Acta Mat., 54, 785-791 (2006).
  2. Lingyun Zhang, Shengquan Ou, Joanne Huang, K. N. Tu, Stephen Gee, and Luu Nguyen, "Effect of current crowding on void propagation at the interface between intermetallic compound and solder in flip chip solder joints, " Appl. Phys. Lett., 88, 012106 (2006).
  3. S. W. Liang, T. L. Shao, Chih Chen, Everett C. C. Yeh, and K. N. Tu, "Relieving the current crowding effect in flip-chip solder joints during current stressing, " J. Mater. Res., 21, 137-146 (2006).
  4. M. O. Alam, B. Y. Wu, Y. C. Chan, and K. N. Tu, "High electric current density induced interfacial reactions in the micro Ball Grid Array (BGA) solder joint" Acta Mat., 54, 613-621 (2006).
  5. J. W. Nah, Fei Ren, K. N. Tu, Sridharan Venk, and Gabe Camara, "Electromigration in Pb-free flip chip solder joints on flexible substrates," J. Appl. Phys., 99, 023520 (2006).
  6. Young-Woo Okm Tae-Yeon Seong, Chel-Jong Choi, and K. N. Tu, "Field emission form Ni-disilicide nanorods formed by using implantation of Ni an Si couples with laser annealing," Appl. Phys. Lett., 88, 043106 (2006).
  7. Z. H. Gan, W. Shao, M. Y. Yan, A. V. Vairagar, T. Zaporozhets, M. A. Meyer, A. Krishnamoorthy, , K. N. Tu, A. Gusak, E. Zschech, and S. G. Mhailkar, "Understanding the impact of surface engineering, structure, and design on electromigration through Monte Carlo simulation and in-situ SEM studies," in "Stress-induced phenomena in metallization," AIP Proceedings of 8th Workshop on Stress-induced Phenomena in metallization, Dresden, Germany, vol. 817, p.34-42 (2006)
  8. M. Y. Yan, K. N. Tu, A. V. Vairagar, M. A. Meyer, H. Geisler, A. Preusse, and E. Zschech, "Effect of overburden thicknss on the copper microstructure of dual-inlaid interconnect structures," AIP Proceedings of 8th Workshop on Stress-induced Phenomena in metallization, Dresden, Germany, vol. 817, p. 211-216 (2006).
  9. K. N. Tu, M. Y. Yan, Fei Ren, Joannne Huang, Emily Ou, L. Y. Zhang, and J. W.Nah, "Electromigration in flip chip solder joints," AIP Proceedings of 8th Workshop on Stress-induced Phenomena in metallization, Dresden, Germany, vol. 817, p. 327-338 (2006)
  10. Jae-Woong Nah, Fei Ren, Kyung-Wook Paik, and K. N. Tu, "Effect of electromigration on mechanical shear behavior of flip chip solder joints," J. Mater. Res., 21, 698-702 (2006).
  11. M. O. Alam, B. Y. Wu, Y. C. Chan, and K. N. Tu, "High electric currentdensity induced interfacial reactions in the micro Ball Grid Array (mBGA)solder joint" Acta Materialia, 54, Issue 3, 613-621 (2006).
  12. Annie Huang, A. M. Gusak, K. N. Tu, and Yi-Shao Lai, "Thermomigration in SnPb composite flip chip solder joints," Appl. Phys. Lett., 88, 141911 (2006).
  13. S. W. Liang, Y. W. Chang, T. L. Shao, Chih Chen, and K. N. Tu, "Effect of three-dimensional current and temperature distribution on void formation and propagation in flip chip solder joints during electromigration," Appl. Phys. Lett., 89, 022117 (2006).
  14. Xi Zhang, K. N. Tu, Y. H. Xie, C. H. Tung, and S. Y. Xu, "Single-step fabrication of Ni films with arrayed macropores and nanostructured skeletons," Adv. Mater., 18, 1905-1909 (2006).
  15. Xi Zhang, K. N. Tu, Y. H. Xie, and C. H. Tung, "High aspect ration Ni structure fabricated by electrochemical replication of hydrofluoric acid etched Si," Electrochemical and Solid State Letters, 9, C150-C152 (2006).
  16. R. Agarwal, Shengquan E. Ou, and K. N. Tu, "Electromigration and critical product in eutectic SnPb solder lines at 100 C," J. Appl. Phys., 100, 024909 (2006).
  17. Annie T. Huang, K. N. Tu and Yi-Shao Lai, "Effect of the combination of electromigration and thermomigration on phase migration and partial melting in flip chip composite SnPb solder joints," J. Appl. Phys., 100, 033512 (2006).
  18. Fei Ren, Jae-Woong Nah, K. N. Tu, Bingshou Xiong, Luhua Xu, and John H. L. Pang, "Electromigration induced ductile-to-brittle transition in lead-free solder joints," Appl. Phys. Lett., 89, 141914 (2006).
  19. Luhua Xu, John H. L. Pang and K. N. Tu, "Effect of electromigration-induced back stress gradient on nano-indentation marker movement in SnAgCu solder joints," Appl. Phys. Lett., 89, 221909 (2006).
  20. Fan-Yi Ouyang, K. N. Tu, Yi-Shao Lai, and Andriy M. Gusak, "Effect of entropy production on microstructure change in eutectic SnPb flip chip solder joints by thermomigration." Appl. Phys. Lett., 89, 221906 (2006).
  21. Xi Zhang and K. N. Tu, "Preparation of hierarchically porous nickel from macroporous silicon," J. of Am. Chem. Soc., 128 (47), 15306-15307, Nov. 2006.
  22. Xi Zhang, F. Ren, M. S. Goorsky, and K. N. Tu, "Study of the initial stage of electroless nickel deposition on Si (100) substrates in aqueous alkaline solution", Surface and Coatings Technology, 201 (6), 2724 -2732, Dec. 2006.
  23. Jae-Woong Nah, J. O. Suh, K. N. Tu, Seung Wook Yoon, Vempati Srinivasa Rao, Vaidyanathan Kripesh, and Fay Hua, "Electromigration in flip chip solder joints having a thick Cu column bump and a shallow solder interconnect," J. Appl. Phys., 100, 123513 (2006).


 

2005 Publications
  1. Kejun Zeng, Roger Stierman, Tz-Cheng Chiu, Darvin Edwards, Kazuaki Ano, and K. N. Tu, "Kirkendall void formation in SnPb solder joints on bare Cu and is effect on joint reliability," J. Appl. Phys., 97, 024508-1 to -8 (2005).
  2. J. Gorlich, G. Schmidt, and K. N. Tu, "On the mechanism of the binary Cu/Sn solder reaction," Appl. Phys. Lett., 86, 053106-1 to -3 (2005).
  3. K. N. Tu and U. Goesele, "Hollow nanostructures based on the Kirkendall effect: Design and stability considerations," Appl. Phys. Lett., 86, 093111-1 to-3 (2005).
  4. H. Gan and K. N. Tu, "Polarity effect of electromigration on kinetics of intermetallic compound formation in Pb-free solder v-groove samples," J. Appl. Phys., 97, 063514-1 to 10 (2005).
  5. Y. H. Lin, Y. C. Hu, C. M. Tsai, C. R. Kao and K. N. Tu, "In-situ observation of the void formation and propagation mechanism in solder joints under current stressing," Acta Mat. 53, 2029-2035 (2005).
  6. Y. T. Yeh, C. K. Chou, Y. C. Hsu, Chih Chen, and K. N. Tu, "Threshold current density of electromigration in eutectic SnPb solder," Appl. Phys. Lett., 86, 203504 (2005).
  7. Albert T. Wu, A. M. Gusak, K. N. Tu, and C. R. Kao, "Electromigration induced grain rotation in anisotropic conducting beta-Sn," Appl. Phys. Lett., 86, 241902 (2005).
  8. M. O. Alam, Y. C. Chan, K. N. Tu, and J. K. Kivilahti, "Effect of 0.5 wt% Cu in Sn-3.5% Ag solder ball on the solid state interfacial reaction with the Au/Ni/Cu bond pad for ball grid array (BGA) applications," Chemistry of Materials, Vol. 17, No. 9, pp. 2223-2226 (2005). May 2005.
  9. L. P. Ren and K. N. Tu, "Fundamentals - Silicide formation on Si, " Chapter 5 in "Semiconductor Manufacturing Handbook," edited by Hwaiyu Geng, McGraw-Hill, New York (2005). pp.5.1 to 5.10.
  10. L. P. Ren and K. N. Tu, "Silicide technology for SOI devices," Chapter 8 in "Silicide Technology for Integrated Circuits," edited by L. J. Chen, Institute of Electrical Engineers, UK (2005). pp. 201-228.
  11. T. V. Zaporozhets, A. M. Gusak, K. N. Tu, and S. G. Mhaisalkar, "Three-dimensional simulation of void migration at the interface between thin metallic film and dielectric under electromigration," J. Appl. Phys., 98, 103508 (2005).
  12. K. N. Tu, J. O. Suh, A. T. C. Wu, N. Tamura, and C. H. Tung, "Mechanism and prevention of spontaneous Sn whisker growth," Materials Transactions, 46, 1-9 (2005).
  13. K. N. Tu and J. C. M. Li, "Spontaneous whisker growth on lead-free solder finishes," Materials Science and Engineering A, 409, 131-139 (2005).
  14. E. Zschech, H-J. Engelmann, M. A. Meyer, V. Kahlert, A. V. Vairagar, S. G. Mhaisalkar, A. Krishnamoorthy, M. Y. Yan, K. N. Tu, and V. Sukharev, "Effect of interface strength on electromigration induced inlaid Cu interconnect degradation: experiment and simulation," Zeitschrift fur Metallkunde, 96, 966-971 (2005).
  15. K. Chong, X. Zhang, K. N. Tu, D. Huang, M. C. F. Chang, and Y. H. Xie, "Three dimensional substrate impedence engineering based on p-/p+ Si substrate for mixed signal system-on-chip," IEEE Transaction on Electronic devices, 52, 2440-2446 (2005).
  16. A. V. Vairagar, S. G. Mhaisalkar, M. A. Meyer, E. Zschech, Ahila Krishnamoorthy, K. N. Tu, and A. M. Gusak, "Direct evidence of electromigration failure mechansism in dual-damascene Cu interconnect tree structures," Appl. Phys. Lett. 87, 081909 (2005).
  17. M. Y. Yan, J. O. Suh, F. Ren, K. N. Tu, A. V. Vairagar, S. G. Mhaisalkar, Ahila Krishnamoorthy, "Effect of Cu3Sn coatings on electromigration lifetime improvement of Cu dual-damascene interconnects," Appl. Phys. Lett., 87, 211103 (2005).
  18. J. W. Nah, J. O. Suh, and K. N. Tu "Effect of Current Crowding and Joule Heating on Electromigration induced Failure in Flip Chip Composite Solder Joints Tested at Room Temperature" Journal of Applied Physics, Vol. 98, 013715, (2005)
  19. M. Y. Yan, K. N. Tu, A. V. Vairagar, S. G. Mhaisalkar, and Ahila Krishnamoorthy, "Confinement of electromigration induced void propagation in Cu interconnect by a buried Ta diffusion barrier layer," Appl. Phys. Lett., 87, 261906 (2005)
  20. K. N. Tu and J. C. M. Li, "Spontaneous whisker growth on lead-free solder finishes," Materials Science and Engineering A, 409, 131-139 (2005).
  21. K. N. Tu, J. O. Suh, and A. T. Wu, "Tin whisker growth on lead-free solder finishes," Chapter 6 in "Lead-free Solder Interconnect Reliability," edited by Dongkai Shangguan, ASM International, Materials Park, Ohio (2005). Pp. 147 - 163.

     

Pb-free solder and wetting reactions
  1. H. K. Kim, H. K. Liou, and K. N. Tu, "Morphology of instability of wetting tips of eutectic SnBi , eutectic SnPb, and pure Sn on Cu," J. of Materials Research, 10. 497-504 (1995).
  2. Y. Wang, H. K. Kim, H. K. Liou, and K. N. Tu, "Rapid soldering reactions of eutectic SnBi and eutectic SnPb solder on Pd surfaces," Scripta Metall. And Mater., 32, 2087-2092 (1995).
  3. Y. Wang and K. N. Tu, "Ultra-fast intermetallic compound formation between eutectic SnPb and Pd where the intermetallic is not a diffusion barrier," Appl. Phys. Lett., 67, 1069-071 (1995).
  4. H. K. Kim and K. N. Tu, "Rate of consumption of Cu soldering accompanied by ripening," Appl. Phys. Lett., 67, 2002-2004 (1995).
  5. H. K. Kim and K. N. Tu, "Kinetic analysis of the soldering reaction between eutectic SnPb alloy and Cu accompanied by ripening," Phys. Rev. B53, 16027- 16034 (1996).
  6. Ann A. Liu, H. K. Kim, K. N. Tu, and P. A. Totta, "Spalling of Cu6Sn5 spheroids in the soldering reaction of eutectic SnPb on Cr/Cu/Au thin films," J. Appl. Phys.,80, 2774-2780 (1996).
  7. K. N. Tu, "Cu/Sn interdiffusion reactions: thin film case vs bulk case," Materials Chemistry and Physics, 46, 217-223 (1996).
  8. H. K. Kim, K. N. Tu, and P. A. Totta, "Ripening-assisted asymmetric spalling of Cu-Sn compound spheroids in solder joints on Si wafers," Appl. Phys. Lett. 68, 2204-2206 (1996).
  9. P. G. Kim and K. N. Tu, "Morphology of wetting reaction of eutectic SnPb solder on Au foils," J. Appl. Phys., 80, 3822-3827 (1996).
  10. C. Y. Liu, K. H. Kim, K. N. Tu, and P. A. Totta, "Dewetting of molten Sn on Au/Cu/Cr thin film metallization," Appl. Phys. Lett., 69, 4014-4016 (1996).
  11. H. K. Kim, H. K. Liou, and K. N. Tu, "Three-dimension morphology of a very rough interface formed in the soldering reaction between eutectic SnPb and Cu," Appl. Phys. Lett., 66, 2337-2339 (1995).
  12. P. G. Kim, K. N. Tu, and D. C. Abbott, "Effect of Pd thickness on soldering reaction between eutectic SnPb and plated Pd/Ni thin films on Cu leadframe," Appl. Phys. Lett. 71, 61-63 (1997).
  13. G. Z. Pan, Ann A. Liu, H, K, Kim, K. N. Tu, and P. A. Totta, "Microstructure of phased-in Cr-Cu/Cu/Au bump-limiting-metallization and its soldering behavior with high Pb and eutectic SnPb solders," Appl. Phys. Lett., 71, 2946-2948 (1997).
  14. C. Y. Liu, and K. N. Tu, "Morphology of wetting reactions of SnPb alloys on Cu as a function of alloy composition," J. Materials Research, 13, 37-44 (1998).
  15. P. G. Kim and K. N. Tu, "Fast dissolution and soldering reactions on Au foils," Materials Chemistry & Physics, 53/2, 165-171 (1998)
  16. D. W. Zheng, Weijia Wen, and K. N. Tu, "Reactive wetting and dewetting induced diffusion-limited aggregation," Phys. Rev. E57, R3719-R3722 (1998).
  17. D. W. Zheng, Z. Y. Jia, C. Y. Liu, Weijia Wen, and K. N. Tu, "Size dependent dewetting and sideband reaction of eutectic SnPb on Au/Cu/Cr thin film," J. Materials Research 13, 1103-1106 (1998).
  18. P. G. Kim, K. N. Tu, and D. C. Abbott, "Time and temperature dependent wetting behavior of eutectic SnPb on Cu lead-frame plated with Pd/Ni and Au/Pd/Ni thin films," J. Appl. Phys. 84, 770-775 (1998).
  19. C. Y. Liu, and K. N. Tu, "Reactive flow of molten Pb(Sn) alloys in Si grooves coated with Cu film," Phys. Rev. E58, 6308-6311 (1998).
  20. D. W. Zheng, Weijia Wen, K. N. Tu, and P. A. Totta, "In-situ scanning electron microscopy study of eutectic SnPb and pure Sn wetting on Au/Cu/Cr multi-layered thin films, " J. Materials Research, 14, 745-749 (1999).
  21. C. Y. Liu, Chih Chen, K. Mal, and K. N. Tu, "Direct correlation of mechanical failure and metallurgical reaction in flip chip solder joints," J. Appl. Phys. 85, 3882-3886 (1999).
  22. J. W. Jang, P. G. Kim, K. N. Tu, D. Frear, and P. Thompson, "Solder reaction-assisted crystallization of electroless Ni (P) under-bump metallization in low cost flip chip technology," J. Appl. Phys. 85, 8456-8463 (1999).
  23. P. G. Kim, J. W. Jang, K. N. Tu, and D. Frear, "Kinetic analysis of interfacial penetration accompanied by intermetallic compound formation," J. Appl. Phys. 86, 1266-1272 (1999).
  24. C. Y. Liu, Chih Chen, C. N. Liao, and K. N. Tu, "Microstructure-electromigration correlation in a thin stripe of eutectic SnPb solder stressed between Cu electrodes," Appl. Phys. Lett., 75, 58-60, 1999.
  25. J. W. Jang, P. G. Kim, K. N. Tu, and M. Lee, "High temperature Pb-free SnSb solders: wetting and interfacial reactions on Cu foils and phased-in Cu-Cr thin films", J. Materials Research , 14, 3895-3900 (1999).
  26. A. S. Zuruzi, C. H. Chiu, W. T. Chen, S. K. Lahiri, and K. N. Tu, "Interdiffusion of high Sn and high lead (PbSn) solders in low temperature flip chip joints during reflow," Appl. Phys. Lett. 75, 3635-3637 (1999).
  27. A. S. Zuruzi, C. H. Chiu, S. K. Lahiri, and K. N. Tu, "Roughness evolution of Cu6Sn5 intermetallic during soldering and its effect on wettability," J. Appl. Phys. 86, 4916-4921 (1999).
  28. P. G. Kim, J. W. Jang, T. Y. Lee, and K. N. Tu, "Interfacial reaction and wetting behavior in eutectic SnPb solder on Ni/Ti thin films and Ni foils," J. Appl. Phys. 86, 6746-6751 (1999).
  29. C. Y. Liu, K. N. Tu, T. T. Sheng, C. H. Tung, D. R. Frear, and P. Elenius, "Electron microscopy study of interfacial reaction between eutectic SnPb and Cu/Ni(V)/Al thin film metallization," J. Appl. Phys. 87, 750-754 (2000).
  30. J. W. Jang, C. Y. Liu, P. G. Kim, K. N. Tu, A.K. Mal, and D. R. Frear, "Interfacial morphology and shear deformation of slip chip solder joints,' J. Mater. Res. 15, 1679-1687 (2000).
  31. C. Y. Liu, Chih Chen, and K. N. Tu, "Electromigraiton of thin strips of SnPb solder as a function of composition," J. Appl. Phys., 88, 5703-5709 (2000).
  32. J. W. Jang, D. R. Frear, T. Y. Lee, and K. N. Tu, "Morphology of interfacial reaction between Pb-free solders and electroless Ni(P) under-bump-metallization," J. Appl. Phys., 88, 6359-6363 (2000).
  33. T. Y. Lee, K. N. Tu, S. M. Kuo, and D. R. Frear, "Electromigation of eutectic SnPb solder interconnects for flip chip technology," J. Appl. Phys., 89, 3189-3194 (2001).
  34. Q. T. Huynh, C. Y. Liu, Chih Chen, and K. N. Tu, "Electromigration in eutectic PbSn solder lines," J. Appl. Phys. , 89, 4332-4335 (2001).
  35. K. N. Tu, T. Y. Lee, J. W. Jang, L. Li, D. R. Frear, K. Zeng, and J. K. Kivilahti, "Wetting reaction vs. solid state aging of eutectic SnPb on Cu," J. Appl. Phys. 89, 4843-4849 (2001).
  36. K. N. Tu and K. Zeng, "Tin-lead (SnPb) solder reaction in flip chip technology," Materials Science & Engineering reports, R34, 1-58 (2001)
  37. K. N. Tu, Fiona Ku, and T. Y. Lee, "Morphology stability of solder reaction products in flip chip technology," J. Electronic Materials, 30, 1129-1132 (2001).
  38. T. Y. Lee, K. N. Tu, and D. R. Frear, "Electromigration of eutectic SnPb and SnAgCu flip chip solder bumps and under-bump-metallization," J. Appl.Phys., 90, 4502-4508 (2001).
  39. T. Y. Tom Lee, T. Y. Lee, and K. N. Tu, "A study of electromigration in 3-D flip chip solder joint using numerical simulation of heat flux and current density," 2001 IEEE ECTC Proceedings, pp. 558-563 (2001).
  40. C. Y. Liu, Jian Li, G. J. Vandentop, W. J. Choi, and K. N. Tu, "Wetting reaction of Sn-Ag based solder systems on Cu substrates plated with Au," J.Electronic Materials, 30, 521-524 (2001)
  41. D. R. Frear and K. N. Tu, "Metallurgical Factors," Chapter 28 in "Area Array Interconnection Handbook" edited by K. Puttlitz and P. A. Totta,Kluwer Academic Publishers, Boston (2001) pp. 1108-1144. (Book chapter)
  42. Everett C.C. Yeh, W.J. Choi, K.N. Tu, P. Elenius, H. Balkan, "Current-crowding-induced electromigration failure in flip chip solder joints," Appl. Phys. Lett., 80(4), 580-2 (2002).
  43. T. Y. Lee, W. J. Choi, K. N. Tu, J. W. Jang, S. M. Kuo, J. K. Lin, D. R. Frear, K. Zeng, and J. K. Kivilahti, "Morphology, kinetics, and thermodynamics of solid state aging of eutectic SnPb and Pb-free solders (SnAg, SnAgCu, and SnCu) on Cu," J. Materials Research. , 17, 291-301 (2002).
  44. K. Zeng and K. N. Tu, "Six cases of reliability study of Pb-free solder joints in electron packaging technology," Materials Science and Engineering Reports, R38, 55-105 (2002). (A review paper.)
  45. W. J. Choi, T. Y. Lee, K. N. Tu, N. Tamura, R. S. Celestre, A. A. MacDowell, Y. Y. Bong, L. Nguyen, and G. T. T. Sheng, "Structure and kinetics of Sn whisker growth on Pb-free solder finish," 52nd Electronic Component & Technology Conference Proceedings (IEEE Catalog number 02CH3734-5), San Diego, CA, 628-633 (2002).
  46. K. N. Tu, and K. Zeng, "Reliability issues of Pb-free solder joints in electronic packaging technology," 52nd Electronic Component & Technology Conference Proceedings, San Diego, CA, 1194-1200 (2002).
  47. W. J. Choi, E. C. C. Yeh, and K. N. Tu, "Electromigration of flip chip solder bump on Cu/Ni(V)/Al thin film under bump metallization," 52nd Electronic Component & Technology Conference Proceedings, San Diego, CA, 1201-1205 (2002).
  48. H. Gan and K. N. Tu, "Effect of electromigration on intermetallic compound formation in Pb-free solder - Cu interfaces," 52nd Electronic Component & Technology Conference Proceedings, San Diego, CA, 1206-1212 (2002).
  49. H. Gan, W. J. Choi, G. Xu, and K. N. Tu, "Electromigration in flip chip solder joints and solder lines," JOM, 6, 34-37 (2002).
  50. M. Li, F. Zhang, W. T. Chen, K. Zeng, K. N. Tu, H. Balkan, and P. Elenius, "Interfacial microstructure evolution between eutectic SnAgCu solder and Al/Ni(V)/Cu thin films," J. Mater. Res., 17, 1612-1621 (2002).
  51. G. T. T. Sheng, C. F. Hu, W. J. Choi, K. N. Tu, Y. Y. Bong, and Luu Nguyen, " Tin whiskers studied by focused ion beam imaging and transmission electron microscopy," J. Appl. Phys., 92, 64-69 (2002).
  52. A. M. Gusak and K. N. Tu, "Kinetic theory of flux-driven ripening," Phys. Rev. B66, 115403-1 to -14 (2002).
  53. K. N. Tu, A. M. Gusak, and M. Li, "Physics and materials challenges for Pb-free solders," J. Appl. Phys., 93, 1335-1353 (2003). (Applied Physics Reviews - Focused Review)
  54. W. J. Choi, E. C. C. Yeh, and K. N. Tu, "Mean-time-to-failure study of flip chip solder joints on Cu/Ni(V)/Al thin film under-bump metallization," J. Appl. Phys. 94, 5665-5671 (2003)
  55. J. S. Ha, T. S. Oh, and K. N. Tu, "Effect of super-saturation of Cu on reaction and intermetallic compound formation between Sn-Cu solder and thin film metallization," J. Mater. Res. 18, 2109-2114 (2003)
  56. K. Y. Lee, M. Li, and K. N. Tu, "Growth and ripening of (Au,Ni)Sn4 phase in Pb-free and Pb containing solder on Ni/Au metallization," J. Materials Research, 18, 2562-2570 (2003)
  57. M. O. Alam, Y. C. Chan, and K. N. Tu, "Effect of reaction time and P-content on mechanical strength of the interfaces formed between eutectic Sn-Ag solder and Au/electroless Ni(P)/Cu bond pad," J. Appl. Phys., 94, 4108-4115 (2003)
  58. M. O. Alam, Y. C. Chan, and K. N. Tu, "Effect of 0.5 wt. % Cu addition in the Sn-3.5%Ag solder on the dissoluation rate of Cu metallization," J. Appl. Phys., 94, 7904-7909(2003)
  59. M. O. Alam, Y. C. Chan, and K. N. Tu, "Effect of 0.5 wt. % Cu addition in the Sn-3.5%Ag solder on the interfacial reaction with Au/Ni metallizaion," Chemistry of Materials, 15, 4340-4342(2003)
  60. M. O. Alam, Y. C. Chan, and K. N. Tu, "Elimination of Au-embrittlement in solder joints on Au/Ni metallizaion," J. Mater. Res., 19, 1303-1306, May(2004)
  61. M. Date, T. Shoji, M. Fujiyoshi, K. Sato, and K. N. Tu, "Impact Reliability of Solder Joints," The proceedings of the 54th ECTC, Las Vegas, NV, p. 668-674, June 2004.
  62. M. Date, T. Shoji, M. Fujiyoshi, K. Sato, and K. N. Tu, "Impact Reliability of Solder Joints on bond pads," Proceedings of VLSI multilevel interconnection conference, Marina del Rey, CA, p. 205-208 (2004).
  63. M. Date, T. Shoji, M. Fujiyoshi, K. Sato, and K. N. Tu, "Ductile-to-brittle transition in Sn-Zn solder joints measured by impact test," Scripta Materialia, 51, 641-645 (2004).

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Advanced interconnect and low dielectric constant thin films
  1. H. K. Liou, J. S. Huang, and K. N. Tu, "Oxidation of Cu and Cu3Ge thin films," J. Appl. Phys., 77, 5443-5445 (1995).
  2. L. T. Shi, and K. N. Tu, "Finite element stress analysis of failure mechanism in a multi-level metallization structure," J. Appl. Phys., 77, 3037-3041 (1995).
  3. K. L. Lee, C. K. Hu, and K. N. Tu, "In-situ SEM comparison studies on electromigration of Cu and Cu(Sn) alloy for advanced chip interconnects," J. Appl. Phys., 78, 4428-4437 (1995).
  4. J. S. Huang, H. K. Liou, and K. N. Tu, "Polarity effect of electromigration in Ni2Si contacts on Si," Phys. Rev. Lett., 76, 2346-2349 (1996).
  5. J. S. Huang and K. N. Tu, "Novel dopant activation of heavily-doped p+-Si by high current density," Phys. Rev. Lett., 77, 4926-4929 (1996).
  6. C. C. Lin, W.S. Chen, H. L. Hwang, K. Y. J. Hsu, H. K. Liou and K. N. Tu, "Reliability study of submicron Ti silicide contacts," Appl. Surface Science, 92, 660-664 (1996).
  7. J. S. Huang, J. Zhang, A. Cruves, and K. N. Tu, "Grain growth in bulk Cu and Cu(Sn) alloys," Materials Chemistry and Physics, 49, 33-41 (1997).
  8. J. S. Huang, S. S. Huang, K. N. Tu, F. Deng, S. S. Lau, S. L. Cheng and L. J. Chen, "Kinetics of Cu3Ge formation and reaction with Al," J. Appl. Phys., 82,644-649 (1997).
  9. J. S. Huang, K. N. Tu, S. W. Bedell, W. A. Lanford, S. L. Cheng, J. B. Lai, and L.J. Chen, "Polarity effect on failure of Ni and Ni2Si contacts on Si, " J. Appl. Phys., 82, 2370-2377 (1997).
  10. J. S. Huang, C. N. Liao, K. N. Tu, S. L. Cheng and L. J. Chen, "Abnormal electrical behavior and phase changes in implanted p+ and n+ -Si channels under high current densities," J. Appl. Phys. 84, 4788-4796 (1998).
  11. L. A. Chow, Y. H. Xu, B. Dunn, K. N. Tu, and C. Chiang, "Cracking behavior of xerogel silica films on silicon substrates," Appl. Phys. Lett. 73, 2944-2946 (1998).
  12. Yuhuan Xu, Yi-pin Tsai, K. N. Tu, Bin Zhao, Q. Z. Liu, Maureen Brongo, George T. T. Sheng, and C. H. Tung, "Dielectric property and microstructure of a porous polymer materials with ultra-low dielectric constant," Appl. Phys. Lett. 75, 853-855 (1999).
  13. Chih Chen, J. S. Huang, C. N. Liao and K. N. Tu, "Dopant activation of heavily doped SOI by high density currents," J. Appl. Phys., 86, 1552-1557 (1999).
  14. C. N. Liao, Chih Chen and K. N. Tu, "Thermoelectric properties of silicon thin film in SOI," J. Appl. Phys.86, 3204-3208 (1999).
  15. L. A. Chow, B. Dunn, K. N. Tu, and C. Chiang, "The mechanical properties of xerogel silica films derived from stress versus temperature and cracking experiements," J. Appl. Phys. , 87, 7788-7792 (2000).
  16. D. W. Zheng, Xinhua Wang, K. K. Shyu, C. T. Chang, Y. Guo, V. Sarihari, Weijia Wen, and K. N. Tu, "A study of local stress using stress-absorbing Si diaphragm," J. Vac. Sci. Tech. B 17(5), 2178(1999).
  17. K. N. Chen, H. H. Lin, S. L. Cheng, Y. C. Peng, G. H. Shen, L. J. Chen, C. R. Chen, J. S. Huang, and K. N. Tu, "Silicide formation in implanted channels and interfacial reactions of metal contacts under high current density," J. Mater. Res. 14, 4720-4726 (1999).
  18. D. W. Zheng, Y. H. Xu, Y. P. Tsai, K. N. Tu, P. Patterson, Bin Zhao, Q. Z. Liu, and Maureen Brongo, "Mechanical property measurement of thin polymeric low dielectric constant films using bulge testing methods," Appl. Phys. lett., 76, 2008-2010 (2000).
  19. Y. H. Xu, Y. P. Tsai, D. W. Zheng, K. N. Tu, C. W. Ong, C. L. Choy, Bin Zhao, Q. Z. Liu, and Maureen Brongo, "Measurement of mechanical properties for dense and porous polymer films having a low dielectric constant," J. Appl. Phys., 88, 5744-5750 (2000).
  20. J. S. Huang, Chih Chen, C. C. Yeh, K. N. Tu, T. L. Shofner, J. D. Drown, R. B. Irwin, and C. B. Vartuli, "Effect of current crowding on contact failure in heavily doped n+- and p+-silicon-on-insulator," J. Mater. Res. , 15, 2387-2392 (2000).
  21. Everett C. C. Yeh and K. N. Tu, "Effects of contact resistance and film thickness on current crowding and critical product of electromigration in Blech structures," J. Appl. Phys., 89, 3203-3208 (2001).
  22. H. H. Lin, S. L. Cheng, L. J. Chen, Chih Chen and K. N. Tu, "Enhanced dopant activation and elimination of end-of-range defects in BF2-implanted silicon-on-insulator by high-density current," Appl. Phys. Lett., 79, 3971-3973 (2001)
  23. Z. B. Zhang, J. S. Huang, M. Twiford, E. Martin, N. Layadi, A. Salah, B. Bhowmik, D. Vitkavago, S. Lytle, E. C. C. Yeh, and K. N. Tu, "A robust multilevel interconnect module for sub-quarter-micrometer complementary metal oxide semiconductor technology integration," J. of Electrochemical Society, 149, G324-G329 (2002).
  24. D. W. Zheng, X. H. Wang, K. Shyu, Chih Chen, C. T. Chang, K. N. Tu, A. J. Mal, and Y. F. Guo, "Stress relaxation of a patterned microstructure on a diaphragm," J. Materials Research, 17, 1795-1802 (2002).
  25. C. N. Liao and K. N. Tu, "Direct measurement of contact temperature using Seebeck potential," J. Appl. Phys., 92, 635-637 (2002).
  26. K. N. Tu, "Recent advances on electromigration in very-large-scale-integration of interconnects," J. Appl. Phys., 94, 5451-5473 (2003). (Applied Physics Review)
  27. Chel-Jong Choi, Sung-Young Chang, Young-Woo Ok, Tae-Yeon Seong, H. Gan, G.Z. Pan, and K.N. Tu, "Formation of Nickel Disilicide Using Nickel Implantation and Rapid Thermal Annealing " J. Electronic Materials . 32, 1072-1078 (2003 October)
  28. A. V. Vairagar, S. G. Mhaisalkar, Ahila Krishnamoorthy, K.N. Tu, A.M. Gusak, Moritz Andreas Meyer, Ehrenfried Zschech, "In-situ observation of electromigration induced void migration in dual-damascene Cu interconnect structures," Appl. Phys. Lett., 85, 2502-2504 (2004)
  29. K. N. Tu, "Electromigration in VLSI of thin film interconnects," Proceedings of 5th International Conference on Thin Film Physics and Applications, Shanghai, edited by J. H Chu, Z. S. Lai, L. W. Wang, and S.H. Xu, SPIE vol. 5774-01, pp. 1-4 (2004).

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Dislocations and grain boundaries in Si
  1. G. Z. Pan, K. N. Tu, and S. Prussin, "Size-distribution of end-of-range dislocation loops in Si-implanted Si," Appl. Phys. Lett., 68, 1654-1656 (1996).
  2. Chih Chen, G. Z. Pan, and K. N. Tu, "Preparation of twist-type bicrystals of Si," Materials Chemistry and Physics, 47, 90-92 (1997).
  3. G. Z. Pan, K. N. Tu, and S. Prussin, "Size distribution and annealing behavior of end-of -range dislocation loops in Si-implanted Si," J. Appl. Phys. 81, 78-84 (1997).
  4. G. Z. Pan, K. N. Tu, and S. Prussin, "Microstructural evolution of (113) rodlike defects and (111) dislocation loops in Si-implanted Si," Appl. Phys. Lett., 71, 659- 601 (1997).
  5. G. Z. Pan and K. N. Tu, "Transmission electron microscopy on (113) rodlike defects and (111) dislocation loops in silicon-implanted silicon," J. Appl. Phys. 82, 601-608 (1997).
  6. Chih Chen, K. N. Tu, C. H. Tung, T. T. Sheng, A. Ploessl, R. Scholz, and U. Goesele, " Twist-type Si bicrystals and compliant substrates prepared from SOI wafers," Phil. Mag. A80, 881-891 (2000).
  7. C. N. Liao, C. Chen, J. S. Huang, and K. N. Tu, "Asymmetrical heating behavior of doped Si channels in bulk Si and in SOI under high current density," J. Appl. Phys. 86, 6895-6901 (1999).
  8. C. N. Liao, Y. P. Tsai, Y. Xu, K. N. Tu, B. Zhao, Q. Z. Liu, and Maureen Brongo, "Thermal conductivity measurement of low-k inter-layer-dielectric thin films," J. Appl. Phys. (submitted).

    9.

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Phase change driven by high current density, high electric and magnetic fields
  1. Weijia Wen, D. W. Zheng, and K. N. Tu, "In-situ time response measurement of the microspheres dispersed in electrorheological fluids, " Phys. Rev. E57, 4516-4519 (1998).
  2. Weijia Wen, D. W. Zheng, K. N. Tu, "Fractal or Chain? Which is the preferred spatial configuration in field-induced solid particle/liquid phase separation?" Phys. Rev. E58, 7682-7685 (1998).
  3. Weijia Wen, D. W. Zheng, and K. N. Tu, "Experimental investigation for the time- dependent effect in electrorheological fluids under time-regulated high pulse electric field," Review of Scientific Instruments, 69, 3573-3576 (1998).
  4. Weijia Wen, F. Kun, K. F. Pal, D. W. Zheng, and K. N. Tu, "Aggregation kinetics and stability of structures formed by magnetic microspheres," Phys. Rev. E59, R4758-R4761, (1999).
  5. Weijia Wen, Ning Wang, D. W. Zheng, and K. N. Tu, "Two and three-dimensional matrixes formed by magnetic microspheres," J. Materials Research, 14, 1186-1189 (1999).
  6. Weijia Wen, D. W. Zheng, and K. N. Tu, "Chain/column evolution and corresponding electrorheological effect," J. Appl. Phys. 85, 530-533 (1999).
  7. Weijia Wen, D. W. Zheng, and K. N. Tu, "Field induced coarsening of electrorheological suspensions," App. Phys. Lett. (submitted).
  8. F. evolution in tin studied by synchrotron x-ray microdiffraction," Appl. Phys. Lett. 85, 2490-2492(2004).

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Nanoscale Interdiffusion and Reactions
  1. C.B. Boothroyd, W.M. Stobbs and K.N. Tu, "The Formation of Submicron Epitaxial Islands of Pd2Si on Silicon," Appl. Phys. Lett. 50, 577-579, (1987).
  2. L. A. Clevenger, C. V. Thompson, and K. N. Tu, "Explosive silicidation in nickel/amorphous-silicon multilayer thin films," J. Appl. Phys., 67, 2894-2898 (1990).
  3. E. Ma, C. V. Thompson, L. A. Clevenger, and K. N. Tu, "Self- propagating explosive reaction in Al/Ni multilayer thin films," Appl. Phys. Lett., 57, 1262-1264 (1990).
  4. K. N. Tu and U. Goesele, Hollow nanostructures based on the Kirkendall effect: Design and stability considerations,?Appl. Phys. Lett., 86, 093111-1 to-3 (2005).

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Other basic and applied research
  1. F. G. Si and K. N. Tu, "Entropic origin of the free energy in nucleation of crystallites in amorphous CoSi2 thin films," Phys. Rev. Lett., 74, 4476-4478 (1995).
  2. T. Laursen, D. Adams, T. L. Alford, K. N. Tu, F. Deng, R. Morton, and S. S. Lau, "Encapsulation of Ag films in Ag-Ti alloy bilayer structures," Thin Solid Films, 290-291, 411-416 (1996).
  3. J. R. LaGraff, G. Z. Pan, and K. N. Tu, "Si ion implantation of STO passivated YBCO films for multi-layer processing," Applied Phys. (submitted).
  4. D. W. Zheng, Xinhua Wang, K. K. Shyu, C. T. Chang, Y. Guo, V. Sarihari, Weijia Wen, and K. N. Tu, "A study of local stress using stress-absorbing Si diaphragm," J. Vac. Sci. Tech., B17, 2178-2181 (1999).
  5. P. S. Nam, L. M. Ferreira, T. Y. Lee, and K. N. Tu, "Study of grass formation in GaAs backside via etching using inductively coupled plasma system," J. Vac. Sci. Tech., B18, 2780-2784 (2000).
  6. K. N. Tu, A. M. Gusak, and I. Sobchenko, "Linear rate of grain growth in thin films during deposition, " Phys. Rev. B67, 245408-1 to -5 (2003).
  7. A. M. Gusak and K. N. Tu, "Theroy of normal grain growth in normalized size space", Acta Mat., 51/13, 3895-3904 (2003).
  8. Shengquan Ou, Gu Xu, Yuhuan Xu, and K.N. Tu, "Optical fiber packaging by lead (Pb)-free solder in V-grooves", Ceramics International, 30, 1115-1119 (2004).
  9. G. Z. Pan, R. P. Ostrumov, Y. Lian, K. N. Tu, and K. L. Wang, "{113} defect-engineered silicon light emitting diodes", IEDM Tech Digest, pp. 343-346, Dec. (2004)

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