In this work, a novel fabrication of Au/hydrogen silsesquioxane (HSQ) and Cu/HSQ damascene structures by hot-embossing and a simple post curing process is proposed. The various embedded metal nanowires in HSQ films can be obtained by various post-curing conditions. The transferring of metal nanowires on flexible material, parylene-C/polyimide, is also demonstrated.
The Au nanowires were fabricated by E-beam lithography and immersion plating. The growth mechanism of Au nanowires is investigated. The effects of immersion plating bath, immersion temperature, and immersion time were also studied. The morphology and grain size were obtained by scanning electron microscope (SEM) and atomic force microscopy (AFM). Grazing incident X-ray diffractometer (GIXRD) was used to study the preferential orientation of Au grains. The composition analysis of Au nanowires was examined by Auger electron spectroscopy (AES). The dense Au nanowires with width of ~100 nm can be obtained by room-temperature immersion Au plating on a-Si surface. The Au nanowires with grain size of ~ 100 nm can be obtained by thermal annealing at 200 oC for 30 min. The resistivities are 3.1-3.9 μΩ cm measured by conductive atomic force microscopy (C-AFM). The Au nanowires were transferred onto HSQ by hot-embossing at room temperature with pressure of 2.2-4.6 Mpa. Post curing at 300-400 oC for 5 s-30 min was then applied to the sample to fabricate embedded Au nanowires in the HSQ film. The Au nanowires were also transferred onto flexible material, parylene-C/polyimide, by hot-embossing at temperature of ~120 oC with pressure of 2.2-4.6 Mpa. The resistivities of transferred Au nanowires were 4-5 μΩ cm.
The Cu nanowires were also prepared by e-beam lithography and room-temperature immersion plating on a-Si. The effect of thermal annealing on Cu nanowires was studied. The coalesced Cu grains with size of ~100 nm in Cu nanowires can be obtained by thermal annealing at 400 oC for 5 s. The morphology and grain sizes were studied by SEM, AFM, and transmission electron microscopy (TEM). The resistivities are 4.8-5.3 μΩ cm. The size-dependent melting temperature of Cu nanocrystallines was examined at temperature of 500-750 oC. The element distribution on the Cu nanowires was obtained by Auger electron spectroscopy (AES). After the Cu nanowires were transferred onto HSQ film at RT with pressure of 2.2-3.3 Mpa, the Cu/HSQ damascene structure was fabricated at 350 oC for 10 s or 400 oC for 5 s. The transferred Cu nanowires were embedded to the depth of ~30 nm by post curing at 400 oC for 60 s. The chemical structure of HSQ film was investigated by Fourier transform infrared spectroscopy (FTIR). Furthermore, the parallel damascene Cu/HSQ interconnects with width/spacing = 100 nm/100 nm were fabricated. The line-to-line leakage current was measured as a function of electric field at temperature of 25-200 oC to investigate the leakage current conduction mechanism. The phonon-assisted hopping conduction was found to responsible for the leakage current. The trap level, and hopping distance were further analyzed from the leakage current data. Finally, the transferring of Cu nanowires on parylene-C/polyimide was demonstrated. The topography, cross section, and grain size of Cu nanowires and transferred Cu nanowires were examined by scanning electron microscope (SEM) and AFM. Meanwhile, the surface roughness of Cu nanowires and damascene structure was obtained by AFM operating in tapping mode. The Cu nanowires were also transferred onto parylene-C/polyimide by hot-embossing at temperature of ~120 oC with pressure of 3.3 Mpa.

本實驗提出一新穎的製作方法製作金/含氫矽酸鹽(hydrogen silsesquioxane) 及銅/含氫矽酸鹽的鑲嵌奈米金屬線。其為利用熱壓印技術和一簡單烘烤過程來完成此製作。藉由不同的烘烤條件可控制不同的金屬線嵌入深度。另外，奈米金屬線轉移於軟性機板(聚對二甲苯/聚亞醯胺)的技術也在此論文中展示。
奈米金線是利用電子束微影技術和浸鍍法所製作。金線的成長機制將在此論文中探討。浸鍍液的濃度，浸鍍的溫度和時間對於金線生長的影響也將被研究。金晶粒的優選晶向為由低掠角X光繞射儀來得到。奈米金線的成份分析為利用歐傑電子能譜儀來進行。寬度為100 nm、緻密的奈米金線可利用非晶矽為基材進行金的浸鍍而得到。表面型態和晶粒大小為由掃描式電子顯微鏡和原子力顯微鏡來得到。晶粒大小為100 nm的奈米金屬線可以藉由溫度200 oC時間30 min的熱退火得到。利用接觸式原子力顯微鏡量得其電阻率為3.1-3.9 μΩ cm。
在利用熱壓印技術在室溫、壓力2.2-4.6 Mpa下轉印奈米金線於含氫矽酸鹽上後，溫度300-400 oC 時間 5 s-30 min的烘烤接著施加於試片上以得到鑲嵌於含氫矽酸鹽內的奈米金線。奈米金線也利用熱壓印技術在溫度120 oC、壓力4.6 Mpa下轉移到聚對二甲苯/聚亞醯胺軟性基板上。轉移後金線電阻率為 4-5 μΩ cm。
奈米銅線也為利用電子束微影技術和於非晶矽基板上以浸鍍法製備。熱退火溫度對奈米銅線的影響將被研究。表面型態和晶粒大小為由掃描式電子顯微鏡、原子力顯微鏡和穿隧式電子顯微就來進行研究。晶粒大小為100 nm的奈米銅線可藉由熱退火在400 oC時間5 s而得到。其電阻率為4.8-5.3 μΩ cm。奈米銅晶粒的尺寸效應對於其熔點的影響將於退火溫度為400-750 oC下作研究。奈米金屬線的表面元素分布為由歐傑電子能譜儀來進行。
在奈米銅線於室溫、壓力2.2-3.3 Mpa下被轉印於含氫矽酸鹽上後，大馬士革銅鑲嵌結構可於對試片作溫度350 oC 時間 10 s 或 溫度400 oC時間5 s的烘烤而獲得。在烘烤溫度400 oC時間60 s的條件下，奈米銅線可埋入含氫矽酸鹽到30 nm的深度。此外，寬度/間距 = 100 nm/100 nm的平行大馬士革奈米銅導線也利用此新穎方法製作出。在量測溫度25-200 oC下，我們藉由量測平行導線間漏電流來進一步了解其漏電流機制。聲子輔助跳躍傳導被發現為主要的漏電流傳導機制，缺陷能階，電子跳躍距離能藉由對漏電流作分析而得到。奈米銅線和轉印後的奈米銅線的表面形態、截面和晶粒大小為利用掃描式電子顯微鏡和輕敲式原子力顯微鏡來分析。同時輕敲式原子力顯微鏡也利用來研究奈米銅線和大馬士革鑲嵌結構的表面粗糙度。另外，奈米銅線也利用熱壓印技術在溫度120 oC、壓力3.3 Mpa下轉移到聚對二甲苯/聚亞醯胺軟性基板上。

References
1. www.itrs.net.
2. A. Ishikawa, Y. Shishida, T. Yamanishi, N. Hata, T. Nakayama, N. Fujii, H. Tanaka, H. Matsuo and T. Kikkawa, "Recovery processes of CMP-induced damages for copper/porous silica damascene interconnects", J. Electrochem. Soc., 154, H400 (2007).
3. T.-S. Kim, T. Konno, T. Yamanaka and R. H. Dauskardt, "Quantitative Roadmap for Optimizing CMP of Ultra-Low-k Dielectrics," in Interconnect Technology Conference, p. 171 (2008).
4. S. Y. Chou, P. R. Krauss and P. J. Renstrom, "Imprint of sub-25 nm vias and trenches in polymers", Applied Physics Letters, 67, 3114 (1995).
5. S. Y. Chou, P. R. Krauss and P. J. Renstrom, "Nanoimprint lithography", J. Vac. Sci. Technol. B, 14, 4129 (1996).
6. S. Matsui, Y. Igaku, H. Ishigaki, J. Fujita, M. Ishida, Y. Ochiai, H. Namatsu and M. Komuro, "Room-temperature nanoimprint and nanotransfer printing using hydrogen silsequioxane", J. Vac. Sci. Technol. B, 21, 688 (2003).
7. G. M. Schmid, M. D. Stewart, J. Wetzel, F. Palmieri, J. J. Hao, Y. Nishimura, K. Jen, E. K. Kim, D. J. Resnick, J. A. Liddle and C. G. Willson, "Implementation of an imprint damascene process for interconnect fabrication", J. Vac. Sci. Technol. B, 24, 1283 (2006).
8. M. T. Li, L. Chen and S. Y. Chou, "Direct three-dimensional patterning using nanoimprint lithography", Applied Physics Letters, 78, 3322 (2001).
9. S. S. Hiroshi Ono, Fabrication of Multilayer Interconnection Using Ultraviolet Nanoimprint Lithography, in Fourth International Conference on Networked Sensing Systems, p. 130 (2007).
10. J. Albero, L. Nieradko, C. Gorecki, H. Ottevaere, V. Gomez, H. Thienpont, J. Pietarinen, B. Paivanranta and N. Passilly, "Fabrication of spherical microlenses by a combination of isotropic wet etching of silicon and molding techniques", Opt. Express, 17, 6283 (2009).
11. H. G. Shin, J. T. Kwon, Y. H. Seo and B. H. Kim, "Fabrication of polmer master for antireflective surface using hot embossing and aao process", International Journal of Modern Physics B, 22, 5887 (2008).
12. P. Schneider, C. Steitz, K. H. Schafer and C. Ziegler, "Hot embossing of pyramidal micro-structures in PMMA for cell culture", Physica Status Solidi a-applications and Materials, 206, 501 (2009).
13. S. R. Nugen, P. J. Asiello and A. J. Baeumner, "Design and fabrication of a microfluidic device for near-single cell mRNA isolation using a copper hot embossing master", Microsyst. Technol., 15, 477 (2009).
14. Z. J. Hu, M. W. Tian, B. Nysten and A. M. Jonas, "Regular arrays of highly ordered ferroelectric polymer nanostructures for non-volatile low-voltage memories", Nat. Mater., 8, 62 (2009).
15. K. Q. Peng and J. Zhu, "Simultaneous gold deposition and formation of silicon nanowire arrays", Journal of Electroanalytical Chemistry, 558, 35 (2003).
16. K. Q. Peng, Y. J. Yan, S. P. Gao and J. Zhu, "Dendrite-assisted growth of silicon nanowires in electroless metal deposition", Adv. Funct. Mater., 13, 127 (2003).
17. T. Qiu, X. L. Wu, Y. F. Mei, P. K. Chu and G. G. Siu, "Self-organized synthesis of silver dendritic nanostructures via an electroless metal deposition method", Applied Physics a-Materials Science & Processing, 81, 669 (2005).
18. C. Carraro, R. Maboudian and L. Magagnin, "Metallization and nanostructuring of semiconductor surfaces by galvanic displacement processes", Surf. Sci. Rep., 62, 499 (2007).
19. T. Qiu, X. L. Wu, Y. F. Mei, G. J. Wan, P. K. Chu and G. G. Siu, "From Si nanotubes to nanowires: Synthesis, characterization, and self-assembly", Journal of Crystal Growth, 277, 143 (2005).
20. C. H. Ting and M. Paunovic, "Selective electroless metal-deposition for integrated-circuit fabrication", J. Electrochem. Soc., 136, 456 (1989).
21. L. Magagnin, R. Maboudian and C. Carraro, "Gold deposition by galvanic displacement on semiconductor surfaces: Effect of substrate on adhesion", Journal of Physical Chemistry B, 106, 401 (2002).
22. L. A. Nagahara, T. Ohmori, K. Hashimoto and A. Fujishima, "Effects of HF solution in the electroless deposition process on silicon surfaces", Journal of Vacuum Science Technology A, 11, 763 (1993).
23. G. Oskam, J. G. Long, A. Natarajan and P. C. Searson, "Electrochemical deposition of metals onto silicon", J. Phys. D-Appl. Phys., 31, 1927 (1998).
24. H. S. L. F.G. Menga, a, L.B. Liua, Z.P. Jina, "Thermodynamic description of the Au–Si–Sn system ", Journal of Alloys and Compounds, 431, 292 (2007).
25. M. Tsuji, M. Hashimoto, Y. Nishizawa and T. Tsuji, "Synthesis of gold nanorods and nanowires by a microwave-polyol method", Mater. Lett., 58, 2326 (2004).
26. C. H. Wang, D. C. Sun and X. H. Xia, "One-step formation of nanostructured gold layers via a galvanic exchange reaction for surface enhancement Raman scattering", Nanotechnology, 17, 651 (2006).
27. H. Okamoto, "Cu-Si (Copper-Silicon)", Journal of Phase Equilibria and Diffusion, 23, 281 (2002).
28. E. Balaur, Y. Zhang, T. Djenizian, R. Boukherroub and P. Schmuki, "Organic monolayers as resist layers for Cu deposition on Si (111) surfaces", J. Electroceram., 16, 71 (2006).
29. M. Takagi, "Electron-diffraction study of liquid-solid transition of thin metal films", J. Phys. Soc. Jpn., 9, 359 (1954).
30. P. Buffat and J. P. Borel, "Size effect on the melting temperature of gold particles", Physical Review A, 13, 2287 (1976).
31. C. Ozdogan and S. Erkoc, "Molecular-dynamics simulation of the structural stability, energetics, and melting of Cu-n(n=13-135) clusters", Z. Phys. D-Atoms Mol. Clusters, 41, 205 (1997).
32. S. L. Lai, J. Y. Guo, V. Petrova, G. Ramanath and L. H. Allen, "Size-Dependent Melting Properties of Small Tin Particles: Nanocalorimetric Measurements", Physical Review Letters, 77, 99 (1996).
33. L. Wang, Y. N. Zhang, X. F. Bian and Y. Chen, "Melting of Cu nanoclusters by molecular dynamics simulation", Phys. Lett. A, 310, 197 (2003).
34. F. Ercolessi, W. Andreoni and E. Tosatti, "Melting of small gold particles: Mechanism and size effects", Physical Review Letters, 66, 911 (1991).
35. H. M. Lu, F. Q. Han and X. K. Meng, "Size-dependent thermodynamic properties of metallic nanowires", Journal of Physical Chemistry B, 112, 9444 (2008).
36. O. A. Yeshchenko, I. M. Dmitruk, A. A. Alexeenko and A. M. Dmytruk, "Size-dependent melting of spherical copper nanoparticles embedded in a silica matrix", Physical Review B, 75, 6 (2007).
37. J. W. Kang and H. J. Hwang, "Molecular dynamics simulation study of the melting of ultra-thin copper nanowires", J. Korean Phys. Soc., 40, 946 (2002).
38. T. Karabacak, J. S. DeLuca, P. I. Wang, G. A. Ten Eyck, D. Ye, G. C. Wang and T. M. Lu, "Low temperature melting of copper nanorod arrays", Journal of Applied Physics, 99, 6 (2006).
39. H. C. Liou and J. Pretzer, "Effect of curing temperature on the mechanical properties of hydrogen silsesquioxane thin films", Thin Solid Films, 335, 186 (1998).
40. C. C. Yang and W. C. Chen, "The structures and properties of hydrogen silsesquioxane (HSQ) films produced by thermal curing", J. Mater. Chem., 12, 1138 (2002).
41. H. J. Lee, E. K. Lin, H. Wang, W. L. Wu, W. Chen and E. S. Moyer, "Structural comparison of hydrogen silsesquioxane based porous low-k thin films prepared with varying process conditions", Chemistry of Materials, 14, 1845 (2002).
42. M. J. Loboda, C. M. Grove and R. F. Schneider, "Properties of a-SiOx : H thin films deposited from hydrogen silsesquioxane resins", J. Electrochem. Soc., 145, 2861 (1998).
43. C. S. Thomas A. Deis, Eric Moyer, Kyuha Chung, Youfan Liu, Mike Spaulding, John Albaugh, Wei Chen, and Jeff Bremmer, "Ultra low-k inorganic silsesquioxane films with tunable electrical and mechanical properties," in Mat. Res. Soc. Symp. , p. D5.18.1 (2000).
44. T. C. Chang, P. T. Liu, T. M. Tsai, F. S. Yeh, T. Y. Tseng, M. S. Tsai, B. C. Chen, Y. L. Yang and S. M. Sze, "Elimination of dielectric degradation for chemical-mechanical planarization of low-k hydrogen silisesquioxane", Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Short Notes Rev. Pap., 40, 3143 (2001).
45. T. C. Chang, Y. S. Mor, P. T. Liu, T. M. Tsai, C. W. Chen, Y. J. Mei and S. M. Sze, "Enhancing the resistance of low-k hydrogen silsesquioxane (HSQ) to wet stripper damage", Thin Solid Films, 398, 523 (2001).
46. Y. Yamada, N. Konishi, J. Noguchi and T. Jimbo, "Influence of CMP slurries and post-CMP cleaning solutions on cu interconnects and TDDB reliability", J. Electrochem. Soc., 155, H485 (2008).
47. http://flexdisplay.asu.edu.
48. A. Kahouli, A. Sylvestre, L. Ortega, F. Jomni, B. Yangui, M. Maillard, B. Berge, J. C. Robert and J. Legrand, "Structural and dielectric study of parylene C thin films", Applied Physics Letters, 94, 3 (2009).
49. Y. Y. Song, Z. D. Gao, J. J. Kelly and X. H. Xia, "Galvanic deposition of nanostructured noble-metal films on silicon", Electrochem. Solid State Lett., 8, C148 (2005).
50. L. Vitos, A. V. Ruban, H. L. Skriver and J. Kollar, "The surface energy of metals", Surf. Sci., 411, 186 (1998).
51. P. Gorostiza, R. Diaz, F. Sanz and J. R. Morante, "Different behavior in the deposition of platinum from HF solutions on n- and p-type (100) Si substrates", J. Electrochem. Soc., 144, 4119 (1997).
52. C. P. daRosa, R. Maboudian and E. Iglesia, "Copper deposition onto silicon by galvanic displacement: Effect of silicon dissolution rate", J. Electrochem. Soc., 155, E70 (2008).
53. B. Kalache, P. R. Cabarrocas and A. F. Morral, "Observation of incubation times in the nucleation of silicon nanowires obtained by the vapor-liquid-solid method", Jpn. J. Appl. Phys. Part 2 - Lett. Express Lett., 45, L190 (2006).
54. C. Kittel, Introduction to Solid State Physics, New work (2005).
55. A. Hiraki, J. W. Mayer and E. Lugujjo, "Formation of silicon oxide over gold layers on silicon substrates", Journal of Applied Physics, 43, 3643 (1972).
56. A. Hiraki, M. A. Nicolet and J. W. Mayer, "Low-temperature migration of silicon in thin layers of gold and platinum", Applied Physics Letters, 18, 178 (1971).
57. A. K. Green and E. Bauer, "Formation, structure, and orientation of gold silicide on gold surfaces", Journal of Applied Physics, 47, 1284 (1976).
58. K. Shabtai, S. R. Cohen, H. Cohen and I. Rubinstein, "A composite gold-silicon oxide surface for mesoscopic patterning", Journal of Physical Chemistry B, 107, 5540 (2003).
59. O. Yevtushenko, H. Natter and R. Hempelmann, "Grain-growth kinetics of nanostructured gold", Thin Solid Films, 515, 353 (2006).
60. a. B. P. Liwei Wang, "Investigation of the influence of grain size, texture and orientation on the mechanical behavior of freestanding polycrystalline gold films," in Materials Research Society, p. 0924 (2006).
61. Y. Toivola, J. Thurn and R. F. Cook, "Structural, electrical, and mechanical properties development during curing of low-k hydrogen silsesquioxane films", J. Electrochem. Soc., 149, F9 (2002).
62. L. Lu, N. R. Tao, L. B. Wang, B. Z. Ding and K. Lu, "Grain growth and strain release in nanocrystalline copper", Journal of Applied Physics, 89, 6408 (2001).
63. Q. J. Huang, C. M. Lilley, M. Bode and R. Divan, "Surface and size effects on the electrical properties of Cu nanowires", Journal of Applied Physics, 104 (2008).
64. W. Steinhogl, G. Schindler, G. Steinlesberger, M. Traving and M. Engelhardt, "Comprehensive study of the resistivity of copper wires with lateral dimensions of 100 nm and smaller", Journal of Applied Physics, 97, 7 (2005).
65. M. Naka, M. Kubo and I. Okamoto, "Wettability of silicon-nitride by aluminum, copper and silver", J. Mater. Sci. Lett., 6, 965 (1987).
66. L. Magagnin, R. Maboudian and C. Carraro, "Selective deposition of thin copper films onto silicon with improved adhesion", Electrochem. Solid State Lett., 4, C5 (2001).
67. S. M. Sze and K. K. Ng, Physics of Semiconductor Devices, Wiley, New York (2007).
68. M. Shimoyama, S. Chikaki, R. Yagi, K. Kohmura, H. Tanaka, N. Fujii, T. Nakayama, T. Ono, A. Ishikawa, H. Matsuo, K. Kinoshita and T. Kikkawa, "A Cu electroplating solution for porous Low-k/Cu damascene interconnects", J. Electrochem. Soc., 154, D692 (2007).
69. J. D. McBrayer, R. M. Swanson and T. W. Sigmon, "Diffusion of metals in silicon dioxide", J. Electrochem. Soc., 133, 1242 (1986).
70. N. F. Mott and E. A. Davis, Electronic Processes in Non-crystalline Materials, Clarendon Press, Oxford (1979).