高等学校化学学报

高等学校化学学报 ›› 2000, Vol. 21 ›› Issue (S1): 222.

• Chemistry in Materials Sciences • 上一篇    下一篇

Self-aligned Submonolayer Cobalt Silicide Formation Studied by Variable Temperature Scanning Tunneling Microscopy in UHV System

YE J. H.1, BAO G. W.2, WANG Yi1,2, Pan J. S.1, LI S. F. Y.2   

  1. 1. Institute of Materials Research and Engineering, 3 Research Link 3, Singapore 117602, Republic of Singapore;
    2. Department of Chemistry, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 Republic of Singapore
  • 出版日期:2000-12-31 发布日期:2000-12-31
  • 通讯作者: YE J. H. E-mail:jh-ye@imre.org.sg
  • 基金资助:

    The authors are grateful to the National Science and Technology Board (NSTB) of Singapore for the financial support (NSTB/172/2/1-12).

Self-aligned Submonolayer Cobalt Silicide Formation Studied by Variable Temperature Scanning Tunneling Microscopy in UHV System

YE J. H.1, BAO G. W.2, WANG Yi1,2, Pan J. S.1, LI S. F. Y.2   

  1. 1. Institute of Materials Research and Engineering, 3 Research Link 3, Singapore 117602, Republic of Singapore;
    2. Department of Chemistry, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260 Republic of Singapore
  • Online:2000-12-31 Published:2000-12-31
  • Contact: YE J. H. E-mail:jh-ye@imre.org.sg
  • Supported by:

    The authors are grateful to the National Science and Technology Board (NSTB) of Singapore for the financial support (NSTB/172/2/1-12).

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被引次数

39

摘要：

Epitaxial growth of defect free metal silicides with high thermal stability is important to ultra large scale integration devices (ULSI)[1]. Cobalt silicide has been used as an interconnect in CMOS devices due to its low resistivity and good thermal stability[2] and excellent lattice match between cobalt silicide and silicon[3,4]. In the present work, we have investigated epitaxial growth of ultra-thin cobalt layer (ca. 10 Å) by electron beam evaporation of cobalt on Si(111) (7×7) surface followed by thermal annealing up to 700℃ in UHV system. The morphologies and the surface structures of epitaxial silicide formation were investigated by using scanning tunneling microscopy (STM). Adlayer structures of Co silicide after annealing were observed to coexist as the closely and loosely packed clusters at 230℃ separated by a boundary. A new structure with ring-like clusters has (l×l) configuration with 3.5 A spacing between hollows of vicinal clusters at 400℃. Si-rich CoSi2 surfaces terminated by Si bilayers showed (2×2) structures after annealing at 480℃, in which Si-rich CoSi2 clusters were observed to be very mobile at room temperature. As the surface was annealed to above 500℃, The domain island became regular triangles, where atomic resolution of the l×l surface of CoSi2(111) were readily discernable. CoSi2(111) surface is suggested to be terminated by a Si-bilayer.

Abstract:

Epitaxial growth of defect free metal silicides with high thermal stability is important to ultra large scale integration devices (ULSI)[1]. Cobalt silicide has been used as an interconnect in CMOS devices due to its low resistivity and good thermal stability[2] and excellent lattice match between cobalt silicide and silicon[3,4]. In the present work, we have investigated epitaxial growth of ultra-thin cobalt layer (ca. 10 Å) by electron beam evaporation of cobalt on Si(111) (7×7) surface followed by thermal annealing up to 700℃ in UHV system. The morphologies and the surface structures of epitaxial silicide formation were investigated by using scanning tunneling microscopy (STM). Adlayer structures of Co silicide after annealing were observed to coexist as the closely and loosely packed clusters at 230℃ separated by a boundary. A new structure with ring-like clusters has (l×l) configuration with 3.5 A spacing between hollows of vicinal clusters at 400℃. Si-rich CoSi2 surfaces terminated by Si bilayers showed (2×2) structures after annealing at 480℃, in which Si-rich CoSi2 clusters were observed to be very mobile at room temperature. As the surface was annealed to above 500℃, The domain island became regular triangles, where atomic resolution of the l×l surface of CoSi2(111) were readily discernable. CoSi2(111) surface is suggested to be terminated by a Si-bilayer.

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