Physics of Thin Films

Arc vaporization

high current, low voltage discharge
initiate by
- touching electrode surfaces and then separating
- trigger arc by high voltage breakdown
produces large numbers of electrons
- very efficient ionization of film atoms (almost 100 %)
cool anodes to prevent deposition of anode material
avoid molten globules reaching film by bending ions using magnetic fields
Source (atoms -> gas)
- vaporization of cathode by arc
- arc moves over cathode for uniform evaporation
Transport
- arc
  - many electrons between cathode and substrate
  - efficient ionization of atoms from cathode (almost 100%)
  - creates plasma region
- ions can be accelerated toward substrate
  - energies up to 100 eV
  - may lose energy by collisions iin plasma is gas pressure is high
Deposition
- impinging ions may be high energy
  - enhanced chemical reactions
  - film densification
- alloys can be deposited
Parameters:
temperature
- substrate heating and cooling
- heating from ion bombardment
  - adjust with substrate bias
deposition rate
- adjust arc current
- adjust substrate bias to collect more ions
particle energy
- adjust substrate bias