1 Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064, China 2 Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China 3 State key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, China
Cite this article:
Jianxiong ZOU,Bo LIU,Liwei LIN,Ding REN,Guohua JIAO,Yuanfu LU,Kewei XU. Microstructure and Thermal Stability of MoC DopedRu-Based Alloy Films as Seedless Diffusion Barrier. Acta Metall Sin, 2017, 53(1): 31-37.
Cu has been adopted to replace Al for conduction lines and contact structures in very large-scale integrated circuits due to its low resistivity. However, Cu could rapidly react with the SiO2-based dielectric under 300 ℃ and form deep level impurities which are strong sink for carriers, leading to the dielectric degradation of the devices. Therefore, it is important to insert a stable barrier between the Cu wiring and SiO2-based dielectric for suppressing Cu diffusion and improving the adhesive strength. The prediction of international technology roadmap for semiconductors that the thickness of diffusion barrier would be further reduced to 3 nm for 22 nm technology node indicates the widely being used Ta/TaN barrier would be incompetent in the future, since Ta/TaN barrier at the limited thickness exhibits a high resistivity and a columnar grain structure which provides lots of vertical grain boundaries for Cu diffusion. Therefore a directly platable amorphous single barrier with low resistivity is highly desired. In this work, MoC are chosen as impurity to expect for amorphous Ru-based films. The RuMoC films with different components were deposited by RF magnetron co-sputtering with different deposition power ratios of MoC versus Ru targets. The sheet resistances, microstructures and components of the RuMoC films in RuMoC/Si and Cu/RuMoC/p-SiOC∶H/Si structures were studied. The sheet resistances, residual oxygen contents and microstructures of the RuMoC films have close correlation with the doping contents of Mo and C elements which can be easily controlled by tuning the deposition power on MoC target. When the deposition power ratio of MoC versus Ru targets was 0.5, amorphous RuMoC II film with low sheet resistance and residual oxygen content was obtained. After annealing at 500 ℃ the Mo-C and Ru-C bonds were well-preserved and co-suppressed the recrystallization of the film and the increasing of the oxygen content, contributing to excellent thermal stability and electrical properties of Cu/RuMoC II/p-SiOC∶H/Si film.
Fund: Supported by National Natural Science Foundation of China (Nos.11075112 and 11605116), Shenzhen Industry Development Fund Project (Nos.JCYJ20150925163313898 and JCYJ20140417113130693) and Shenzhen Engineering Laboratory Project (No.2012-1127)
Fig.1 Evolution of the compositions and sheet resistance of RuMoC films obtained at different deposition power ratios (PMoC/PRu) (PMoC, PRu—sputtering powers of MoC and Ru targets)
Fig.2 GIXRD patterns of as-deposited Ru (100 nm)/Si, RuMoC I (100 nm)/Si and RuMoC II (100 nm)/Si samples (a), and HRTEM image and Fourier transform (inset) of as-deposited RuMoC II (100 nm)/Si film (b)
Fig.3 Sheet resistances of samples A and B as a function of annealing temperatures (Sample A—Cu/RuMoC II (5 nm)/p-SiOC∶H (200 nm)/Si, Sample B—Cu/Ru (5 nm)/p-SiOC∶H (200 nm)/Si)
Fig.4 GIXRD patterns of sample A (a) and B (b) as-deposited and annealed at different temperatures
Fig.5 XPS spectra of C1s (a), Ru3d (b) and O1s (c) from as-deposited and 500 ℃ annealed RuMoC II samples
Bond
Fitting peak
Binding energy / eV
A0 / %
At / %
Ref.
C1s
C-Ru
280.8
22.1%
21.1
[26]
C-Mo
281.8
68.7%
70.9
[27]
C-C
284.8
9.2%
8.0
[28]
O1s
MoOx
530.5
18.0%
17.0
[29]
RuOx
531.8
82.0%
83.0
[30]
Ru3d
Ru-C
279.2 (Ru3d5/2)
5.9 (Ru3d5/2)
5.6 (Ru3d5/2)
[26]
283.6 (Ru3d3/2)
Ru
280.2 (Ru3d5/2)
92.3 (Ru3d5/2)
90.7 (Ru3d5/2)
[26,28,30]
285.0 (Ru3d3/2)
RuOx
281.8 (Ru3d5/2)
1.8 (Ru3d5/2)
3.7 (Ru3d5/2)
[29~31]
286.2 (Ru3d3/2)
Table 1 Binding energy of fitting peaks and area percentages of C1s, Ru3d and O1s XPS spectra from RuMoC II film
Fig.6 J-E curves of as-deposited and 500 ℃ annealed sample A and 400 ℃ annealed sample B (J—current density, E—electric field intensity)
[1]
Liu B, Song Z X, Li Y H, et al.An ultrathin Zr(Ge) alloy film as an exhaustion interlayer combined with Cu(Zr) seed layer for the Cu/porous SiOC∶H dielectric integration[J]. Appl. Phys. Lett., 2008, 93: 174108
[2]
Rosenberg R, Edelstein D C, Hu C K, et al.Copper metallization for high performance silicon technology[J]. Annu. Rev. Mater. Sci., 2000, 30: 229
[3]
Semiconductor Industry Association.2005 International Technology Roadmap for Semiconductors [Z]. TX, USA: International SEMATECH, 2005: 1
[4]
Chang C A.Formation of copper silicides from Cu(100)/Si(100) and Cu(111)/Si(111) structures[J]. J. Appl. Phys., 1990, 67: 566
[5]
Leu L C, Norton D P, McElwee-White L, et al. Ir/TaN as a bilayer diffusion barrier for advanced Cu interconnects[J]. J. Appl. Phys. Lett., 2008, 92: 111917
[6]
Wang J H, Chen L J, Lu Z C, et al.Ta and Ta-N diffusion barriers sputtered with various N2/Ar ratios for Cu metallization[J]. J. Vac. Sci. Technol., 2002, 20B: 1522
[7]
Yang L Y, Zhang D H, Li C Y, et al. Comparative study of Ta, TaN and Ta/TaN bi-layer barriers for Cu-ultra low-k porous polymer integration [J]. Thin Solid Films, 2004, 462-463: 176
[8]
Hsu K C, Perng D C, Wang Y C.Robust ultra-thin RuMo alloy film as a seedless Cu diffusion barrier[J]. J. Alloys. Compd., 2012, 516: 102
[9]
Arunagiri T N, Zhang Y, Chyan O, et al.5 nm ruthenium thin film as a directly plateable copper diffusion barrier[J]. Appl. Phys. Lett., 2005, 86: 083104
[10]
Liu B, Zhang Y P, Xu K W.Improvement of thermal stability and electrical property of Cu/Cu(Zr)/SiOC∶H film stack by controlling the structure and composition of Zr(Ge) nano-interlayer[J]. Microelectron. Eng., 2014, 118: 41
[11]
Bouhtiyya S, Lucio Porto R, La?k B, et al.Application of sputtered ruthenium nitride thin films as electrode material for energy-storage devices[J]. Scr. Mater., 2013, 68: 659
[12]
Damayanti M, Sritharan T, Mhaisalkar S G, et al.Effects of dissolved nitrogen in improving barrier properties of ruthenium[J]. Appl. Phys. Lett., 2006, 88: 044101
[13]
Jiao G H, Liu B, Li Q R.Investigation of amorphous RuMoC alloy films as a seedless diffusion barrier for Cu/p-SiOC∶H ultralow-k dielectric integration[J]. Appl. Phys., 2015, 120A: 579
[14]
Henderson L B, Ekerdt J G.Time-to-failure analysis of 5 nm amorphous Ru(P) as a copper diffusion barrier[J]. Thin Solid Films, 2009, 517: 1645
[15]
Hsu K C, Perng D C, Yeh J B, et al.Ultrathin Cr added Ru film as a seedless Cu diffusion barrier for advanced Cu interconnects[J]. Appl. Surf. Sci., 2012, 258: 7225
[16]
Wojcik H, Krien C, Merkel U, et al.Characterization of Ru-Mn composites for ULSI interconnects[J]. Microelectron. Eng., 2013, 112: 103
[17]
Cattaruzza E, Battaglin G, Riello P, et al.On the synthesis of a compound with positive enthalpy of formation: Zinc-blende-like RuN thin films obtained by rf-magnetron sputtering[J]. Appl. Surf. Sci., 2014, 320: 863
[18]
Jansson U, Lewin E.Sputter deposition of transition-metal carbide films-a critical review from a chemical perspective[J]. Thin Solid Films, 2013, 536: 1
[19]
Trgala M, ?emli?ka M, Neilinger P, et al.Superconducting MoC thin films with enhanced sheet resistance[J]. Appl. Surf. Sci., 2014, 312: 216
[20]
Huang Q F, Yoon S F, Rusli, et al. Molybdenum-containing carbon films deposited using the screen grid technique in an electron cyclotron resonance chemical vapor deposition system[J]. Diam. Relat. Mater., 2000, 9: 534
[21]
Kacim S, Binst L, Reniers F, et al.Composition and structure of reactively sputter-deposited molybdenum-carbon films[J]. Thin Solid Films, 1996, 287: 25
[22]
Liu B, Yang J J, Liu C H, et al.Ultrathin CuSiN/p-SiC∶H bilayer capping barrier for Cu/ultralow-k dielectric integration[J]. Appl. Phys. Lett., 2009, 94: 153116
[23]
Laurila T, Zeng K, Kivilahti J K, et al.Chemical stability of Ta diffusion barrier between Cu and Si[J]. Thin Solid Films, 2000, 373: 64
[24]
Holloway K, Fryer P M, Cabral C Jr, et al.Tantalum as a diffusion barrier between copper and silicon: failure mechanism and effect of nitrogen additions[J]. J. Appl. Phys., 1992, 71: 5433
[25]
Seibt M, Hedemann H, Riedel A A, et al.Structural and electrical properties of metal silicide precipitates in silicon[J]. Phys. Status Solidi, 1999, 171A: 301
[26]
Lee J S, Yie J E.An XANES study of carbides of molybdenum and tungsten[J]. Korean J. Chem. Eng., 1991, 8: 164
[27]
Bachman B J, Vasile M J.Ion bombardment of polyimide films[J]. J. Vac. Sci. Technol., 1989, 7A: 2709
[28]
Anwar M, Hogarth C A, Bulpett R.Effect of substrate temperature and film thickness on the surface structure of some thin amorphous films of MoO3 studied by X-ray photoelectron spectroscopy (ESCA)[J]. J. Mater. Sci., 1989, 24: 3087
[29]
Shen J Y, Adnot A, Kaliaguine S.An ESCA study of the interaction of oxygen with the surface of ruthenium[J]. Appl. Surf. Sci., 1991, 51: 47
[30]
Hammond J S, Gaarenstroom S W, Winograd N.X-ray photoelectron spectroscopic studies of cadmium- and silver-oxygen surfaces[J]. Anal. Chem., 1975, 47: 2193
[31]
McEvoy A J, Gissler W. ESCA spectra and electronic properties of some ruthenium compounds[J]. Phys. Status Solidi, 1982, 69A: k91
