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Microstructure Characterization for Nano-thick Nickel Cobalt Composite Silicides from 10 nm-Ni0.5Co0.5 Alloy films

10 nm 두께의 니켈 코발트 합금 박막으로부터 제조된 니켈코발트 복합실리사이드의 미세구조 분석

  • 송오성 (서울시립대학교 신소재공학과) ;
  • 김상엽 (서울시립대학교 신소재공학과) ;
  • 김종률 (서울시립대학교 신소재공학과)
  • Published : 2007.04.01

Abstract

We fabricated thermally-evaporated 10 nm-Ni/(poly)Si and 10 nm-$Ni_{0.5}Co_{0.5}$/(Poly)Si structures to investigate the microstructure of nickel silicides at the elevated temperatures required lot annealing. Silicides underwent rapid annealing at the temperatures of $600{\sim}1100^{\circ}C$ for 40 seconds. Silicides suitable for the salicide process formed on top of both the single crystal silicon actives and the polycrystalline silicon gates. A four-point tester was used to investigate the sheet resistances. A transmission electron microscope and an Auger depth profilescope were employed for the determination of vortical microstructure and thickness. Nickel silicides with cobalt on single crystal silicon actives and polycrystalline silicon gates showed low resistance up to $1100^{\circ}C$ and $900^{\circ}C$, respectively, while the conventional nickle monosilicide showed low resistance below $700^{\circ}C$. Through TEM analysis, we confirmed that a uniform, $10{\sim}15 nm$-thick silicide layer formed on the single-crystal silicon substrate for the Co-alloyed case while a non-uniform, agglomerated layer was observed for the conventional nickel silicide. On the polycrystalline silicon substrate, we confirmed that the conventional nickel silicide showed a unique silicon-silicide mixing at the high silicidation temperature of $1000^{\circ}C$. Auger depth profile analysis also supports the presence of this mixed microstructure. Our result implies that our newly proposed NiCo-alloy composite silicide process may widen the thermal process window for the salicide process and be suitable for nano-thick silicides.

Keywords

References

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