Thermal Evaporator System

Deposition

A thermal evaporator uses an electric resistance heater to melt the material and raise its vapor pressure to a useful range. This is done in a high vacuum, both to allow the vapor to reach the substrate without reacting with or scattering against other gasphase atoms in the chamber, and reduce the incorporation of impurities from the residual gas in the vacuum chamber. Thermal evaporation is the simplest way of depositing material onto a substrate.

  • Coating uniformity up to 4” substrate size.
  • Substrate heating up to 200 deg C using localized heaters. 

System Configuration:

Pumping System 

Main Line: 1600L/s. 6” oil diffusion pump; DC 704 silicon oil is used for diffusion pump. 

Roughing Line: 240L/m, direct drive mechanical rotary pump

     

Specifications of the system

  • Uses tungsten or Molybdenum filaments to heat evaporants. 
  • Ultimate chamber pressure 1x10-6mbar.
  • Typical filament currents are 0-200Amps. 
  • Exposes substrate to visible or IR radiation.
  • Maximum deposition thickness that can be achieved is 300nm. 
  • Substrate temperature can be increased up to 200 deg C.

Crystal Monitor 

  • Quartz crystal is used to monitor the thickness of the deposited film and also to  control the rate of evaporation.  
  • Crystal has to be cleaned or changed periodically
 

Thermal Evaporator make

Vacuum techniques

Crystal monitor make

Model DTM -10

Heating filaments/boats

Tungsten, molybdenum

Materials evaporated

Low melting point metals (Al, Cr, Au, Pd, Ti, Ni, Ag)

Pressure in System

1X10-6 mbar
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(c) National Nanofabrication Centre, CeNSE, IISc, 2018.