Person:
Li, Zhefeng

Profile Picture

Email Address

AA Acceptance Date

Birth Date

Research Projects

Organizational Units

Job Title

Last Name

Li

First Name

Zhefeng

Name

Li, Zhefeng

Filters

2010 - 20172

Settings

Author's Publications: search.filters.isAuthorOfPublication.97de17b5-c93b-4730-995a-a1e17aa68d17

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Publication
    Quantitative Evaluation of Cobalt Disilicide/Si Interfacial Roughness
    (The Electrochemical Society, 2017) Yang, Jing; Feng, Jun; Li, Kecheng; Bhandari, Harish B; Li, Zhefeng; Gordon, Roy
    The formation of smooth, conformal cobalt disilicide (CoSi2) without facets or voids is critical for microelectronic device reliability owing to the ultra-shallow contact areas. Here we demonstrate the formation of smooth and conformal CoSi2 films by chemical vapor deposition (CVD) of cobalt nitride (CoxN) films on silicon (Si) or on silicon on insulator (SOI) substrates, followed by in-situ rapid thermal annealing (RTA) at 700°C. To reveal the CoSi2/Si interfacial morphology, we report a back-to-front sample preparation method, in which mechanical polishing, anisotropic tetramethylammonium hydroxide (TMAH) wet etching, hydrofluoric acid (HF) wet etching, and isotropic xenon difluoride (XeF2) dry etching are employed to remove the SOI substrate from the back side to expose the CoSi2/Si interface. This method offers a robust and reliable procedure for quantitative assessment of the CoSi2/Si interfacial roughness, as well as analytical support for advanced fabrication process development.
  • Thumbnail Image
    Publication
    Direct-Liquid-Injection Chemical Vapor Deposition of Nickel Nitride Films and Their Reduction to Nickel Films
    (American Chemical Society, 2010) Li, Zhefeng; Gordon, Roy; Pallem, Venkateswara; Li, Huazhi; Shenai, Deo V.
    Smooth and continuous films of nickel nitride (NiNx) with excellent step coverage were deposited from a novel nickel amidinate precursor, Ni(MeC(NtBu)2)2, and either ammonia (NH3) or a mixture of NH3 and hydrogen (H2) gases as co-reactants. The reactants were injected together in direct-liquid-injection chemical vapor deposition (DLI-CVD) processes at substrate temperatures of 160−200 °C. Depending on the ratio of NH3 to H2 gases during deposition, the Ni:N atomic ratio in DLI-CVD NiNx films could be varied from 3:1 to 15:1, having either a cubic nickel structure or a mixture of hexagonal Ni3N and cubic Ni4N crystal structures with an incorporation of nitrogen as low as 6%. The chemical vapor deposition (CVD) growth rates of NiNx could be increased to more than 5 nm/min. The CVD films were smooth and continuous, and they had 100% step coverage in high-aspect-ratio (>50:1) holes. The as-deposited NiNx films had resistivities as low as 50 μΩ cm for film thicknesses of 25 nm. Annealing of the films in H2 at 160 °C or hydrogen plasma treatment at room temperature removed the nitrogen and led to pure nickel films.