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The development of high-performance integrated circuit chips and the shrinkage of feature sizes according to Moore’s law bring forward continuously the requirements for low dielectric constant (low-k) materials with various excellent properties in the back-end-of-the-line (BEOL) interconnect. Porous SiCOH films prepared by plasma enhanced chemical vapor deposition (PECVD) through a porogen approach are widely applied to industry and extensively studied. Thermal annealing is an important process for fabricating the porous low-k films, which has a great influence on film structure as well as properties. SiCOH films are deposited by PECVD using tetraethoxysilane and limonene as precursors, and annealed at 450 ℃ for 1.5 h under nitrogen atmosphere. The evolutions of film structure and properties during thermal annealing are revealed, and the reaction mechanism for structure change is also proposed. Fourier transform inferred spectroscopy and solid state nuclear magnetic resonance results show that the as-deposited film is an organic-inorganic hybrid film composed of various kinds of Si-O-Si, -CHx, Si-O-CH2CH3, etc. The organic component is removed almost completely during thermal annealing, making a porous film with a Si-O-Si inorganic skeleton. The skeleton is also rearranged at the same time. Deconvolution of the Si-O-Si absorption band of the FTIR spectrum reveals that the cage-like Si-O-Si occupies the major part for both as-deposited and annealed films, while the amount of silicon suboxide Si-O-Si decreases and that of network Si-O-Si increases during thermal annealing, making the film more robust. More C=C and Si-C are formed through chemical reactions between Si-H, -CHx and Si-O-CH2-CH3, and crosslinking is further enhanced. Nitrogen adsorption/desorption isothermal measurement reveals that a large number of micropores with diameter less than 2-3 nm are created during thermal annealing, which is consistent with the removal of organic groups and the existence of cage-like Si-O-Si. As a result, both the refractive index and dielectric constant decrease significantly from 1.476 (λ =630 nm) and 3.45 to 1.365 and 2.60, respectively. Because of the increase of C=C after annealing, extinction coefficient and leakage current density increase. Although there is a shrinkage of 14.7% in film thickness and a reduction of mechanical properties after annealing, the Young’s modulus is still larger than 4 GPa. Considering all kinds of properties, the obtained film appears to be a competitive candidate as inter layer dielectrics in the BEOL interconnect of integrated circuits.
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Keywords:
- thermal annealing /
- SiCOH film /
- plasma enhanced chemical vapor deposition /
- structure and properties
[1] Baklanov M R, Ho P S, Zschech E 2012 Advanced Interconnects for ULSI Technology (Wiley) pp x-xxi
[2] Davis J A, Meindl J D (translated by Luo Z Y, Ye Z C, L Y Q, Yu W J) 2010 Interconnect Technology and Design for Gigascale Integration (Beijing: China Machine Press) pp1-3 (in Chinese) [戴维斯 J A, 梅因道 J D著(骆祖茔, 叶佐昌, 吕勇强, 喻文健 译) 2010 吉规模集成电路互连工艺及设计(北京: 机械工业出版社) 第1-3页
[3] Volksen W, Miller R D, Dubois G 2010 Chem. Rev. 110 56
[4] Favennec L, Jousseaume V, Rouessac V, Fusalba F, Durand J, Passemard G 2004 Mat. Sci. Semicon. Proc. 7 277
[5] Grill A, Patel V 2001 Appl. Phys. Lett. 79 803
[6] Favennec L, Jousseaume V, Gerbaud G, Zenasni A, Passemard G 2007 J. Appl. Phys. 102 64107
[7] Grill A, Patel V 2008 J. Appl. Phys. 104 24113
[8] Doniat F, Anderson C, Dussarrat C, Mcandrew J, Opila R, Wright B, Yang D 2012 Microelectron. Eng. 92 34
[9] Park J, Choi J K, An C J, Jin M L, Kang S, Yun J, Kong B, Jung H 2013 J. Mater. Chem. C 1 3414
[10] Ye C, Ning Z Y 2010 Chin. Phys. B 19 553
[11] Castex A, Jousseaume V, Deval J, Bruat J, Favennec L, Passemard G 2008 J. Vac. Sci. Technol. 26 1343
[12] Castex A, Favennec L, Jousseaume V, Bruat J, Deval J, Remiat B, Passemard G, Pons M 2005 Microelectron. Eng. 82 416
[13] Gourhant O, Gerbaud G, Zenasni A, Favennec L, Gonon P, Jousseaume V 2010 J. Appl. Phys. 108 124105
[14] Gates S M, Neumayer D A, Sherwood M H, Grill A, Wang X, Sankarapandian M 2007 J. Appl. Phys. 101 94103
[15] Jousseaume V, Favennec L, Zenasni A, Gourhant O 2007 Surf. Coat. Technol. 201 9248
[16] Jousseaume V, Zenasni A, Favennec L, Gerbaud G, Bardet M, Simon J P, Humbert A 2007 J. Electrochem. Soc. 154 G103
[17] Zenasni A, Jousseaume V, Holliger P, Favennec L, Gourhant O, Maury P, Gerbaud G 2007 J. Appl. Phys. 102 94107
[18] Grill A, Neumayer D A 2003 J. Appl. Phys. 94 6697
[19] Du J, Ye C, Yu X Z, Zhang H Y, Ning Z Y 2009 Acta Phys. Sin. 1 575 (in Chinese) [杜杰, 叶超, 俞笑竹, 张海燕, 宁兆元 2009 1 575]
[20] Yan J M, Zhang Q Y 1979 Adsorption and Condensation: Surface and Pores of Solids (Beijing: Liberation Press) pp111-116 (in Chinese) [严继民, 张启元 1979 吸附与凝聚: 固体的表面与孔(北京: 解放出版社)第111-116页
[21] Gates S M, Dubois G, Ryan E T, Grill A, Liu M, Gidley D 2009 J. Electrochem. Soc. 156 G156
[22] Jiang T, Zhu B, Ding S J, Fan Z Y, Zhang D W 2014 J. Mater. Chem. C 2 6502
[23] Xu H Y, Wang X B, Wu Z Y 2006 Chem. Res. Chin. Univ. 1 104 (in Chinese) [徐洪耀, 王献彪, 吴振玉 2006 高等学校化学学报 1 104]
[24] Marsik P, Verdonck P, de Roest D, Baklanov M R 2010 Thin Solid Films 518 4266
[25] Baklanov M R, Zhao L, Besien E V, Pantouvaki M 2011 Microelectron. Eng. 88 990
[26] Dubois G, Volksen W, Magbitang T, Miller R D, Gage D M, Dauskardt R H 2007 Adv. Mater. 19 3989
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[1] Baklanov M R, Ho P S, Zschech E 2012 Advanced Interconnects for ULSI Technology (Wiley) pp x-xxi
[2] Davis J A, Meindl J D (translated by Luo Z Y, Ye Z C, L Y Q, Yu W J) 2010 Interconnect Technology and Design for Gigascale Integration (Beijing: China Machine Press) pp1-3 (in Chinese) [戴维斯 J A, 梅因道 J D著(骆祖茔, 叶佐昌, 吕勇强, 喻文健 译) 2010 吉规模集成电路互连工艺及设计(北京: 机械工业出版社) 第1-3页
[3] Volksen W, Miller R D, Dubois G 2010 Chem. Rev. 110 56
[4] Favennec L, Jousseaume V, Rouessac V, Fusalba F, Durand J, Passemard G 2004 Mat. Sci. Semicon. Proc. 7 277
[5] Grill A, Patel V 2001 Appl. Phys. Lett. 79 803
[6] Favennec L, Jousseaume V, Gerbaud G, Zenasni A, Passemard G 2007 J. Appl. Phys. 102 64107
[7] Grill A, Patel V 2008 J. Appl. Phys. 104 24113
[8] Doniat F, Anderson C, Dussarrat C, Mcandrew J, Opila R, Wright B, Yang D 2012 Microelectron. Eng. 92 34
[9] Park J, Choi J K, An C J, Jin M L, Kang S, Yun J, Kong B, Jung H 2013 J. Mater. Chem. C 1 3414
[10] Ye C, Ning Z Y 2010 Chin. Phys. B 19 553
[11] Castex A, Jousseaume V, Deval J, Bruat J, Favennec L, Passemard G 2008 J. Vac. Sci. Technol. 26 1343
[12] Castex A, Favennec L, Jousseaume V, Bruat J, Deval J, Remiat B, Passemard G, Pons M 2005 Microelectron. Eng. 82 416
[13] Gourhant O, Gerbaud G, Zenasni A, Favennec L, Gonon P, Jousseaume V 2010 J. Appl. Phys. 108 124105
[14] Gates S M, Neumayer D A, Sherwood M H, Grill A, Wang X, Sankarapandian M 2007 J. Appl. Phys. 101 94103
[15] Jousseaume V, Favennec L, Zenasni A, Gourhant O 2007 Surf. Coat. Technol. 201 9248
[16] Jousseaume V, Zenasni A, Favennec L, Gerbaud G, Bardet M, Simon J P, Humbert A 2007 J. Electrochem. Soc. 154 G103
[17] Zenasni A, Jousseaume V, Holliger P, Favennec L, Gourhant O, Maury P, Gerbaud G 2007 J. Appl. Phys. 102 94107
[18] Grill A, Neumayer D A 2003 J. Appl. Phys. 94 6697
[19] Du J, Ye C, Yu X Z, Zhang H Y, Ning Z Y 2009 Acta Phys. Sin. 1 575 (in Chinese) [杜杰, 叶超, 俞笑竹, 张海燕, 宁兆元 2009 1 575]
[20] Yan J M, Zhang Q Y 1979 Adsorption and Condensation: Surface and Pores of Solids (Beijing: Liberation Press) pp111-116 (in Chinese) [严继民, 张启元 1979 吸附与凝聚: 固体的表面与孔(北京: 解放出版社)第111-116页
[21] Gates S M, Dubois G, Ryan E T, Grill A, Liu M, Gidley D 2009 J. Electrochem. Soc. 156 G156
[22] Jiang T, Zhu B, Ding S J, Fan Z Y, Zhang D W 2014 J. Mater. Chem. C 2 6502
[23] Xu H Y, Wang X B, Wu Z Y 2006 Chem. Res. Chin. Univ. 1 104 (in Chinese) [徐洪耀, 王献彪, 吴振玉 2006 高等学校化学学报 1 104]
[24] Marsik P, Verdonck P, de Roest D, Baklanov M R 2010 Thin Solid Films 518 4266
[25] Baklanov M R, Zhao L, Besien E V, Pantouvaki M 2011 Microelectron. Eng. 88 990
[26] Dubois G, Volksen W, Magbitang T, Miller R D, Gage D M, Dauskardt R H 2007 Adv. Mater. 19 3989
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