Hostname: page-component-8448b6f56d-jr42d Total loading time: 0 Render date: 2024-04-19T13:26:20.063Z Has data issue: false hasContentIssue false
  • English
  • Français

Impedance analysis of amorphous and polycrystalline tantalum oxide sputtered films

Published online by Cambridge University Press:  09 March 2011

Guneet Sethi ,
Brian Bontempo ,
Eugene Furman ,
Mark W. Horn ,
Michael T. Lanagan ,
S.S.N. Bharadwaja  and
Jing Li
Guneet Sethi*
Affiliation:
Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802
Brian Bontempo
Affiliation:
Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802
Eugene Furman
Affiliation:
Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802
Mark W. Horn
Affiliation:
Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802
Michael T. Lanagan
Affiliation:
Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802
S.S.N. Bharadwaja
Affiliation:
Center for Dielectric Studies, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802
Jing Li
Affiliation:
Center for Dielectric Studies, Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania 16802
*
a)Address all correspondence to this author. e-mail: guneet.sethi@gmail.com
Get access

Abstract

Impedance spectroscopy studies were conducted on amorphous tantalum oxide thin films prepared using pulsed-DC reactive sputtering, which were post-annealed to crystallize the films. X-ray diffraction results showed that crystallization to Ta2O5 β phase occurs for samples annealed above 650 °C, with a crystallite size of ∼40 nm. The film microstructure was studied by electron microscopy, and remnants of the columnar amorphous microstructure were found in the polycrystalline films. Complex impedance analyses revealed significant differences in dielectric behavior between the amorphous and crystalline films. Lumped circuit models were conducted on the films using resistors, capacitors, and constant phase elements. Amorphous films exhibited a single relaxation with Arrhenius activation energy of 1.1–1.3 eV. Crystallized films exhibited two relaxations with activation energies equal to 1.1 ± 0.08 and 0.6 ± 0.03 eV. The relative permittivity of the bulk crystalline grain in tantalum oxide films is close to the established permittivity of the β phase (εr = 40) of Ta2O5.

Keywords

SputteringDielectric PropertiesThin Film
Type
Articles
Information
Journal of Materials Research , Volume 26 , Issue 6 , 28 March 2011 , pp. 745 - 753
Copyright
Copyright © Materials Research Society 2011

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1.Atanassova, E. and Paskaleva, A.: Challenges of Ta2O5 as high-k dielectric for nanoscale DRAMs. Microelectron. Reliab. 47, 913 (2007).CrossRefGoogle Scholar
2.Kukli, K., Ihanus, J., Ritala, M., and Leskelä, M.: Properties of Ta2O5-based dielectric nanolaminates deposited by atomic layer epitaxy. J. Electrochem. Soc. 144, 300 (1997).CrossRefGoogle Scholar
3.Spassov, D. and Atanassova, E.: Conduction mechanisms in Ta2O5 stack in response to rapid thermal annealing. Microelectron. Eng. 85, 214 (2008).CrossRefGoogle Scholar
4.Wang, C.W., Lin, R.D., Chen, S.F., and Lin, W.K.: Effects of O2 rapid thermal annealing on the microstructural properties and reliability of RF-sputtered Ta2O5 films. IEEE Trans. Dielectr. Electr. Insul. 7, 316 (2000).CrossRefGoogle Scholar
5.Ezhilvalavan, S. and Tseng, T.Y.: Electrical properties of Ta2O5 thin films deposited on Cu. Thin Solid Films 360, 268 (2000).CrossRefGoogle Scholar
6.Ezhilvalavan, S. and Tseng, T.Y.: Electrical properties of Ta2O5 thin films deposited on Ta. Appl. Phys. Lett. 74, 2477 (1999).CrossRefGoogle Scholar
7.Dimitrova, T., Arshak, K., and Atanassova, E.: Crystallization effects in oxygen annealed Ta2O5 thin films on Si. Thin Solid Films 381, 31 (2001).CrossRefGoogle Scholar
8.Ezhilvalavan, S. and Tseng, T.Y.: Conduction mechanisms in amorphous and crystalline Ta2O5 thin films. J. Appl. Phys. 83, 4797 (1998).CrossRefGoogle Scholar
9.Chen, K., Nielsen, M., Rymaszewski, E., and Lu, T.: Study of electron trapping in the amorphous tantalum oxide thin films prepared by DC magnetron reactive sputtering. Mater. Chem. Phys. 49, 42 (1997).CrossRefGoogle Scholar
10.Kerrec, O., Devilliers, D., Groult, H., and Marcus, P.: Study of dry and electrogenerated Ta2O5 and Ta/Ta2O5/Pt structures by XPS. Mater. Sci. Eng. B 55, 134 (1998).CrossRefGoogle Scholar
11.Atanassova, E., Tyuliev, G., Paskaleva, A., Spassov, D., and Kostov, K.: XPS study of N2 annealing effect on thermal Ta2O5 layers on Si. Appl. Surf. Sci. 225, 86 (2004).CrossRefGoogle Scholar
12.Ezhilvalavan, S. and Tseng, T.Y.: Short-duration rapid thermal annealing processing of tantalum oxide thin films. J. Am. Ceram. Soc. 82, 600 (1999).CrossRefGoogle Scholar
13.Pignolet, A., Mohan Rao, G., and Krupanidhi, S.B.: Rapid thermal processed thin films of reactively sputtered Ta2O5. Thin Solid Films 258, 230 (1995).CrossRefGoogle Scholar
14.Andreoni, W. and Pignedoli, C.A.: Ta2O5 polymorphs: Structural motifs and dielectric constant from first principles. Appl. Phys. Lett. 96, 062901 (2010).CrossRefGoogle Scholar
15.Chaneliere, C., Autran, J.L., Devine, R.A.B., and Balland, B.: Tantalum pentoxide (Ta2O5) thin films for advanced dielectric applications. Mater. Sci. Eng. R 22, 269 (1998).CrossRefGoogle Scholar
16.Shibata, S.: Dielectric constants of Ta2O5 thin films deposited by r.f. sputtering. Thin Solid Films 277, 1 (1996).CrossRefGoogle Scholar
17.Pavlovic, A.S.: Some dielectric properties of tantalum pentoxide. J. Chem. Phys. 40, 951 (1964).CrossRefGoogle Scholar
18.Verkerk, B., Winkel, P., and de Groot, D.G.: On the mechanism of anodic oxidation of tantalum. Philips Res. Rep. 13, 506 (1958).Google Scholar
19.Kimura, H., Mizuki, J., Kamiyama, S., and Suzuki, H.: Extended x-ray absorption fine structure analysis of the difference in local structure of tantalum oxide capacitor films produced by various annealing methods. Appl. Phys. Lett. 66, 2209 (1995).CrossRefGoogle Scholar
20.Lau, W.S. and Leong, L.L., Han, T., and Sandler, N.P.: Detection of oxygen vacancy defect states in capacitors with ultrathin Ta2O5 films by zero-bias thermally stimulated current spectroscopy. Appl. Phys. Lett. 83, 2835 (2003).CrossRefGoogle Scholar
21.Kim, I.I., Ahn, S.-D., Cho, B.-W., Ahn, S.-T., Lee, J.Y., Chun, J.S., and Lee, W.-J.: Microstructure and electrical properties of tantalum oxide thin film prepared by electron cyclotron resonance plasma-enhanced chemical vapor deposition. Jpn. J. Appl. Phys. 33, 6691 (1994).CrossRefGoogle Scholar
22.Jeon, S.R., Han, S.W., and Park, J.W.: Effect of rapid thermal annealing treatment on electrical properties and microstructure of tantalum oxide thin film deposited by plasma enhanced chemical vapor deposition. J. Appl. Phys. 77, 5978 (2009).CrossRefGoogle Scholar
23.Lohrengel, M.M.: Thin anodic oxide layers on aluminium and other valve metals: High field regime. Mater. Sci. Eng. R 11, 243 (1993).CrossRefGoogle Scholar
24.Leach, J.S.L. and Pearson, B.R.: Crystallization in anodic oxide films. Corros. Sci. 28, 43 (1988).CrossRefGoogle Scholar
25.Ohishi, T., Maekawa, S., and Katoh, A.: Synthesis and properties of tantalum oxide films prepared by the sol-gel method using photo-irradiation. J. Non-Cryst. Solids 147–148, 493 (1992).CrossRefGoogle Scholar
26.Sethi, G., Sunal, P., Horn, M.W., and Lanagan, M.T.: Influence of reactive sputter deposition conditions on crystallization of zirconium oxide thin films. J. Vac. Sci. Technol. A 27, 577 (2009).CrossRefGoogle Scholar
27.Cullity, B.D.: Elements of X-ray Diffraction (Addison-Wesley, Reading, MA, 1978).Google Scholar
28.Beckage, P., Knorr, D., Wu, X., Lu, T., and Rymaszewski, E.: Discrete β-Ta2O5 crystallite formation in reactively sputtered amorphous thin films. J. Mater. Sci. 33, 4375 (1998).CrossRefGoogle Scholar
29.Bales, G.S. and Zangwill, A.: Macroscopic model for columnar growth of amorphous films by sputter deposition. J. Vac. Sci. Technol. A 9, 145 (1991).CrossRefGoogle Scholar
30.Thornton, J.A.: Influence of apparatus geometry and deposition conditions on structure and topography of thick sputtered coatings. J. Vac. Sci. Technol. 11, 666 (1974).CrossRefGoogle Scholar
31.Sethi, G., Olszta, M., Li, J., Sloppy, J., Horn, M.W., Dickey, E.C., and Lanagan, M.T.: Structure and dielectric properties of amorphous tantalum pentoxide thin film capacitors, in Proceedings of. 2007 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2007, pp. 815–818.CrossRefGoogle Scholar
32.Treacy, M.M.J. and Gibson, J.M.: Variable coherence microscopy: A rich source of structural information from disordered materials. Acta Crystallogr. A 52, 212 (1996).CrossRefGoogle Scholar
33.Gibson, J.M., Treacy, M.M.J., and Voyles, P.M.: Atom pair persistence in disordered materials from fluctuation microscopy. Ultramicroscopy 83, 169 (2000).CrossRefGoogle ScholarPubMed
34.Voyles, P.M., Treacy, M.M.J., and Gibson, J.M.: Fluctuation microscopy: A probe of atomic correlations in disordered materials. J. Electron Microsc. (Tokyo) 49, 259 (2000).CrossRefGoogle ScholarPubMed
35.Bottcher, C.J.F. and Bordewijk, P.: Theory of Electric Polarization: Dielectric in Time-Dependent Fields, Vol. II. (Elsevier, Amsterdam, 1992).Google Scholar
36.Jonscher, A.K.: The ‘universal’ dielectric response. Nature 267, 673 (1977).CrossRefGoogle Scholar
37.Kutty, T.R.N. and Ezhilvalavan, S.: The role of silica in enhancing the nonlinearity coefficients by modifying the trap states of zinc oxide ceramic varistors. J. Phys. D Appl. Phys. 29, 809 (1996).CrossRefGoogle Scholar
38.Jõgi, I.: Conduction Mechanisms in Thin Atomic Layer Deposited Films Containing TiO2 (University of Tartu, Estonia, 2007).Google Scholar
39.Ramprasad, R.: First principles study of oxygen vacancy defects in tantalum pentoxide. J. Appl. Phys. 94, 5609 (2003).CrossRefGoogle Scholar
40.Saraf, L., Wang, C.M., Shutthanandan, V., Zhang, Y., Marina, O., Baer, D.R., Thevuthasan, S., Nachimuthu, P., and Lindle, D.W.: Oxygen transport studies in nanocrystalline ceria films. J. Mater. Res. 20, 1295 (2005).CrossRefGoogle Scholar
41.Yang, G.Y., Lian, G.D., Dickey, E.C., Randall, C.A., Barber, D.E., Pinceloup, P., Henderson, M.A., Hill, R.A., Beeson, J.J., and Skamser, D.J.: Oxygen nonstoichiometry and dielectric evolution of BaTiO3. II: Insulation resistance degradation under applied dc bias. J. Appl. Phys. 96, 7500 (2004).CrossRefGoogle Scholar
42.Duggan, M.J., Saito, T., and Niwa, T.: Ionic conductivity of tantalum oxide by RF sputtering. Solid State Ion 62, 15 (1993).CrossRefGoogle Scholar
43.Abram, E.J., Sinclair, D.C., and West, A.R.: A strategy for analysis and modeling of impedance spectroscopy data of electroceramics: Doped lanthanum gallate. J. Electroceram. 10, 165 (2003).CrossRefGoogle Scholar
44.Jonscher, A.K.: Dielectric Relaxation in Solids (Chelsea Dielectrics Press, London, 1983).Google Scholar
45.Morrison, F.D., Jung, D.J., and Scott, J.F.: Constant-phase-element (CPE) modeling of ferroelectric random-access memory lead zirconate-titanate (PZT) capacitors. J. Appl. Phys. 101, 094112 (2007).CrossRefGoogle Scholar
46.McHale, A.E. and Filler, H.L.: Defects and charge transport in β-Ta2O5: Analysis of the conductivity observed in nominally pure β-Ta2O5. J. Am. Ceram. Soc. 68, 646 (2006).CrossRefGoogle Scholar
47.Kyritsis, A., Pissi, P., and Grammatikakis, I.: Dielectric relaxation spectroscopy in poly(hydroxyethyl acrylates)/water hydrogels. J. Polym. Sci. B: Polym. Phys. 33, 1737 (1995).CrossRefGoogle Scholar
48.Shannon, R.D.: Dielectric polarizabilities of ions in oxides and fluorides. J. Appl. Phys. 73, 348 (1993).CrossRefGoogle Scholar