Processes and Technologies for Micro and Nanoelectronics

Barrier and Metal Chemical Vapor Deposition (CVD) – UPDATE coming

Barrier and e.g. copper CVD processes are used for the metallization of interconnects as an alternative process to PVD and electroplating. CVD processes gain more and more importance for 3D integration, especially in the case that structures with high aspect ratios have to be metallized. Fraunhofer ENAS possess many years of experience in this area.

Amorphous interlayer which leads to insufficient adhesion of copper deposited by CVD.
© Fraunhofer ENAS
Amorphous interlayer which leads to insufficient adhesion of copper deposited by CVD.
Application of an adhesion layer (TiN based) impedes formation of interlayer, layer stack pass copper CMP without failure.
© Fraunhofer ENAS
Application of an adhesion layer (TiN based) impedes formation of interlayer, layer stack pass copper CMP without failure.
SEM image of a cobalt oxide layer.
© Fraunhofer ENAS
SEM image of a cobalt oxide layer.

CVD of diffusion barrier: TiN

  • Precursor: TDMAT
  • Multistep process consisting of alternating MOCVD deposition and plasma treatment steps
  • Process optimization for high step coverage with regard to pattern geometry and density
  • Stabilization with SiH4 for a better performance of the diffusion barrier, mainly at structure sidewalls
  • Deposition of adhesion layer for copper CVD, e.g. for a subsequent CMP process

Copper-CVD

  • Thermal MOCVD with CupraSelect™
  • Complete fill of structures
  • Deposition of seed layers for electroplating
  • Metallization of through-silicon vias (TSV): with barrier/ seed for geometries >3 µm; complete CVD fill for geometries <3 µm
  • Process optimization for high step coverage with regard to structure geometry and depth, also very high aspect ratios (e.g. >20)
  • Metallization of nanometer sized interconnects (<100 nm)

Screening of new metal-organic precursors

  • Evaluation of new copper precursors for thermal deposition or reactive deposition
  • Testing of other precursors for metal, metal alloy and barrier deposition (e.g. Ru, Sn, Mn)

Equipment

The Fraunhofer ENAS has an Applied Materials P5000™ tool for processing wafers up to 200 mm wafer diameter, equipped with two CVD-chambers (one for Cu-CVD and one for TiN-CVD) and a plasma pretreatment chamber. Both CVD chambers are based on WxZ chambers and have different evaporation systems for liquid precursors, a Bronkhorst system with a liquid delivery system as well as a bubbler system.
 

Publications

Melzer, M.; C. K. Nichenametla; C. Georgi; H. Lang; S. E. Schulz.: Low-Temperature Chemical Vapor Deposition of Cobalt Oxide Thin Films from a Dicobaltatetrahedrane Precursor. RSC Advances 7, no. 79 (2017): 50269–78. https://doi.org/10.1039/C7RA08810H.