Hot filament and hot wire CVD processes

The precipitation of polycrystalline diamond films using hot-filament chemical vapour deposition (CVD, HFCVD) is a core competence of the Fraunhofer Institute for Surface Engineering and Thin Films IST. Fully automated HFCVD systems developed at Fraunhofer IST are suitable for coating surfaces up to half a square metre. Processes and systems are also available for the diamond coating of three-dimensional base bodies and for interior diamond coating. Diamond layers with various modifications, for instance with a rough or smooth surface or also as electrically conductive films, are available for different applications.

Hot filament CVD with diamond

Hot filament CVD (chemical vapour deposition) is an established coating method for diamond films.

The technology and its benefits:

  • Chemical precipitation of films from the gas phase (chemical vapour deposition, CVD) following activation of the reactive gas on hot filaments
  • Development of coating processes and systems at Fraunhofer IST
  • Large-scale surface coating (500 x 1000 mm2) with polycrystalline diamond films
  • Diamond coating of three-dimensional base bodies and interior diamond coating
  • Variety of coating modifications adapted to the respective applications

Possible substrate materials: hard metals, silicon, high-melting metals, silicon carbide, silicon nitride, graphite

Applications

Hot wire CVD of silicon-based films

Hot filament CVD also has a number of advantages over proven plasma-assisted coating methods for the production of silicon-based films:

The technology and its benefits

  • Chemical precipitation of films from the gas phase (chemical vapour deposition, CVD) following activation of the reactive gas on hot filaments
  • High gas yields
  • High coating rates
  • Straightforward systems technology
  • Readily scalable to coating large areas
  • Gentle coating process with no damage to the substrate, growing layer through high-energy particle bombardment
  • Excellent energy efficiency
  • Low total cost of ownership

Film types

  • Amorphous and microcrystalline silicon (a-Si:H, μc-Si:H); intrinsic and doped films
  • Silicon nitride (SiNx:H)
  • Silicon carbide (SiCx:H)
  • Silicon-germanium alloys (SiGex:H)

Applications

  • Absorber layers for thin film photovoltaics
  • Anti-reflection and passivation films for monocrystalline and multicrystalline silicon solar cells
  • Thin film transistors (TFT) for displays
  • Films for microelectronics and microsystems
  • Barrier layers and corrosion protection
  • Transparent scratch protection
  • Gentle etching process with atomic hydrogen