Selective Electroless Plated Ni Contacts to CMOS Junctions with CoSi2

G. E. Georgiou, P. F. Bechtold, H. Luftman, T. T. Sheng

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4 Scopus citations


We use selective electroless plated nickel alloys for filling high-aspect-ratio (height/width > 1) windows before sputtering aluminum for the first-level metallization. After briefly discussing the electroless plating process, we describe the physical analysis (cross-section transmission electron microscopy and Auger electron spectroscopy) of the Al(1%Cu)/electroless NiP/CoSi2/Si materials interaction as a function of anneal temperature. We then describe the electrical properties of contact resistance and diode leakage. Here, we study several complimentary metal-oxide-silicon (CMOS) processes with junctions 500–2500 Å deep, below 700 Å CoSi2. The Al/Ni plug metallization does not degrade CMOS devices with nominally 2500-Å-deep junctions, when the subsequent processing temperatures is <400°C. Both Al/Ni and Ni/Si (through CoSi2) interact at above 400°C. At 450°C, the Ni/Si interacts to form enough Ni2Si below CoSi2 to degrade <2000-Å-deep junctions. The Al/Ni interacts to form Al3Ni with discontinuities at window steps. Physical analysis does not indicate interaction between Al, Ni, and Si at 330°C. However, the reverse-bias diode leakage of the ultrashallow junctions 500 A below CoSi2 severely degrades after the Al/Ni metallization is annealed at 330°C.

Original languageEnglish (US)
Pages (from-to)3618-3624
Number of pages7
JournalJournal of the Electrochemical Society
Issue number12
StatePublished - Dec 1991
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry


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