Diffusion, LPCVD (Low Pressure Chemical Vapor Deposition)

Low Pressure CVD (LPCVD) is one of the technologies used to deposit thin films by exposing the substrate to one or more volatile precursors, which react and/or decompose on the surface.
LPCVD applications are typically used in semiconductor manufacturing to create Polysilicon thin films, insulating oxides or passivation layers.

Diffusion is a thermal process used for oxidation and nitration of the wafer surface, or to change the electrical properties of the doped layers.

Application requirements

  • Vacuum performance stability over time for optimized yield
  • High robustness: condensable management, powder handling
  • High process lifetime at low operating costs: Low power consumption, low repair cost

How does it work?
Both LPCVD & Diffusion technologies use thermal energy to activate the chemical reaction, typically in the range of 500 to 900 °C. Besides excellent step coverage & high purity deposition, this technology allows a much larger substrate surface treatment than other CVD technologies. LPCVD or Diffusion equipment are commonly batch types, processing up to 200 wafers simultaneously.

Vacuum requirements
Depending on the material to be deposited, several precursors can be used leading to multiple varieties of by-products to be handled by dry vacuum pumps: Condensable or solid, some applications combining both simultaneously.

Product portfolio
Considering the numbers of wafers processed in a batch furnace, dry pump robustness & process lifetime are critical to insure production throughput: The A4 Series is the perfect fit to meet these challenges.

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