Journal of the Korean Ceramic Society (한국세라믹학회지)

The Korean Ceramic Society (한국세라믹학회)
권호 표지

Leakage Current of Capacitive BST Thin Films

BST 축전박막의 누설전류 평가

  • 인태경 (포항공과대학교 재료금속공학과) ;
  • 안건호 (포항공과대학교 재료금속공학과) ;
  • 백성기 (포항공과대학교 재료금속공학과)
  • Published : 1997.08.01
Download PDF
⟨ Previous Next ⟩

Abstract

Ba0.5Sr0.5TiO3 thin films were deposited by RF magnetron sputliring method in order to clarify the anneal condition and doping effect on loakage current Nb and Al were selected as electron donor and acceptor dopants respectively, in the BST films because they have been known to have nearly same ionic radii as Ti and thought to substitute Ti sites to influence the charge carrier and the acceptor state adjacent to the gram boundary. BST thin films prepared in-situ at elevated temperature showed selatively high leakage current density and low breakdown voltage. In order to achieve smooth surface and to improve electrical properties, BST thin films were deposited at room temperature and annealed at elevated temperature. Post-annealed BST thin films showed smoother surface morphology and lower leakage current density than in-situ prepared thin films. The leakage current density of Al doped thin films was measured to be around 10-8A/cm2, which is much lower than those of undoped and Nb doped BST films. The result clearly demonstrates that higher Schottky barrier and lower mobile charge carrier concentration achieved by annealing in the oxygen atmosphere and by Al doping are desirable for reducing leakage current density in BST thin films.

Ba0.5Sr0.5TiO3박막을 RF 마그네트론 스퍼터링법을 이용하여 Pt/Ti/SiO2/Si(100) 기판에 증착하였다 .누설전류에 영향을 주는 것으로 알려진 열처리 조건, dopant 효과 등을 평가하고자 이온반경이Ti와 유사하고 대부분이 Ti 자리를 치환하는 것으로 알려진 Nb와 Al을 각각 danor와 acceptor로 선택하여 BST 박막에 첨가한 후 누설전류를 측정하였다. 고온에서 in-situ 증착된 BST 박막은 거친 표면 형상을 보이며 낮은 전압에서 파괴가 발생하고, Nb 첨가로 누설전류가 증가하였다. 삼온 증착후 후열처리된 박막은 표면 형상도 평할도가 증가하였으며 in-situ로 제조된 박막에 비해 높은 파괴전압과 낮은 누설전류를 나타내었다. 특히 Al이 첨가된 BST 박막의 누설전류밀도는 ~10A/cm2로 도핑을 하지 않은 박막이나 Nb가 첨가된 박막에 비해 매우 낮은 누설전류밀도를 나타내었으며, 이는 산화로 인한 산소공공의 감소, 이동 가능한 hole의 감소와 후열처리과정중 계면 및 입계의 산화로 Schottky 장벽에 높아진 결과로 판단된다.

Keywords

References

  1. NATO ASI Series v.284 no.373 Science and Technology of Electroceramic Thin Film B. Gnade;S. R. Summerfelt;D Crenshaw;O. Auciello(ed.);R. Waser(ed.)
  2. 요업재료의 과학과 기술 v.9 no.6 고유전율 박막재료의 ULSI-DRAM에서의 응용현황과 전망 황철성
  3. Proc. 8th IEEE Int. Symp. on Applications of Ferroelectrics Microstructure-Induced Schottky Barrier Effects in Barium Strontium Titanate (BST) Thin Films for 16 and 64 Mbit DRAM Cells J. F. Scott;M. Azuma;E. Fujii;T. Otsuki;G. Kano;M. C. Scott;C. A. Paz de Araujo;L.D. McMillan;T. Roberts
  4. J. Am. Ceram. Soc. v.75 no.4 Phase Equilibria in the System Barium Titanate Titanate-Strontium Titanate B A. Wechsler;K.W. Kirby
  5. Jpn. J. Appl. Phy. v.35 no.2B Fabrication and Electrical Characterization of $Pt/(Ba,Sr)TiO_3/Pt$Capacitors for Ultra large-scale Integrated Dynamic Random Access Application S. O. Park;C. S. Hwang;H. -J. Cho;C. S. Kang;H. -K. Kang;S. I. Lee;M. Y. Lee
  6. Jpn. J. Appl. Phys. v.31 Electrical Properties of $SrTiO_3$Thin Films Prepared by RF Sputtering T. Kuroiwa;T. Honda;H. Watarai;K. Sato
  7. Appl. Phys. Lett. v.62 no.10 Eximer Laser Ablated Barium Strontium Titanate Thin Films for Dynamic Random Access Memory Applications D. Roy;S B. Krupanidhi
  8. J. Mater. Res. v.10 no.3 Structures and Electrical Properties of Barium Strontium Titanate Thin Films Grown by Multi-Ion-Beam Reactive Sputtering Technique C J Peng;S B. Krupanidhi
  9. Jpn. J. Appl. Phys. v.33 no.10 Preparation of(Ba, Sr)$TiO_3$Thin Films by chemical Vapor Deposition Using Liquid Sources T. Kawahara;M. Yamamuka;T. Makita;K. Tsutahara;A. Yuuki;K. Ono;Y. Matsui
  10. Proceedings of the IEEE International Symposium on Applications of Ferroelectrics Precursor Dependant Properties of $Ba_1.5Sr_3TiO_3$Thin Films Fabricated by Sol-Gel Method J. Kim;S. I. Kwun;J. G. Yoon
  11. Thin solid Films v.2 Selection of Thin Film Capacitor Dielectrics P. J Harrop;D. S Campbell
  12. Appl. Phys. Lett. v.67 no.19 Deposition of Extremely Thin$(Ba,Sr)TiO_3$Thin Films for Ultra-Large-Scale Integrated Dynamic Random Access Memory Application C S. Hwang;S. O. Park;H. -J. Cho;C S. Kang;H. -K. Kang;S. I. Lee;M. Y. Lee
  13. Jpn. J. Appl. Phys. v.35 Metalorganic Chemical vapor-Deposition of Complex Metal Oxide Thin Films by liquid source Chemical Vapor Deposition P C. Van Buskirk;S. M. Bilodeau;J. F. Roedei;P. S Kirlin
  14. J. Am. Ceram. Soc. v.73 no.7 Application of Zinc Oxide Varistors T. K. Gupta
  15. J. Am. Ceram. Soc. v.73 no.11 Grain-Boundary Chemistry of Barium Titanate and Strontium Titanate: Ⅱ, Orgin of Electrical Brriers in Positive -Temperature-Coefficient Termistors Y. -M. Chiang;T. Takagi
  16. J. Am. Ceram. Soc. v.75 no.3 Effect of Reoxidation on the Grain-Boundary Acceptor-State Density of Reduced BaTiO₃Ceramics I. -C. Ho;S. -L. Fu
  17. J. Am. Ceram. Soc. v.77 no.1 Grain Boundary Defect Chemistry of Acceptor-Doped Titanates Space Charge Layer Width M. Vollman;R. Waser
  18. IEEE. Trans. Components. Hybrids, Manuf. Technol v.CHMT-9 no.4 Charge Carriers and Time Dependent Currents in $BaTiO_3$-Based Ceramic H. Y. Lee;L. C. Burton
  19. J. Am. Ceram. Soc. v.74 no.8 Bulk Conductivity and Defect Chemistry of Acceptor-Doped SrTiO₃in the Quenched State R. Waser
  20. J. Am. Ceram. Soc. v.72 no.12 Defect Chemistry of Relaxor Ferroelectrics and the Implicatins for Dielectric Degradation D M. Smyth;M. P. Harmer;P. Peng
  21. J. Am. Ceram. Soc. v.77 no.3 Transition of Cimpensating Defect Mode in Niobium-Doped Barium Titanate T. -B. Wu;J. -N. Lin
  22. J. Am. Ceram. Soc. v.65 no.3 Nonstoichiometry in Acceptor-Doped BaTiO₃ N.-H Chan;R.K. Sharma;D.M. Smyth
  23. Mat. Res. Soc. Symp. Proc. v.343 Growth and Characterization of $Ba_0.5Sr_0.5TiO_3$Thin Films on Si(100) by$90\circ$Off-Axis Sputtering S. Y. Hou;J. Kwo;R. K. Watts;D J. Werder;J. Shmulovich;H. M. O'Bryan
  24. Jpn. J. Appl. Phys. v.33 no.9B Dielectric properties of $(BaxSr{1-x})TiO_3$Thin Films Prepared by RF Sputtering for Dynamic Random Access Memory Application T. Kuroiwa;Y. Tsunemine;T. Horokawa;T Makita;J. Tanimura;N. Mikami;K. Sato