Deposition (CVD and PVD)

Under what condition does CVD give good step coverage (conformality)?

  1. ASurface-reaction-limited conditions (such as relatively low temperature and low pressure)
  2. BConditions limited by the supply of source gas
  3. CConditions with source gas blown at high speed from one direction
Show answer and explanation

Answer: A. Surface-reaction-limited conditions (such as relatively low temperature and low pressure)

Under surface-reaction-limited conditions, the source gas reaches deep into trenches before reacting at the surface, so the deposition rate varies little with location and films deposit uniformly on sidewalls and bottoms. Under supply-limited conditions, films tend to be thicker at openings where gas arrives more easily.

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More Deposition (CVD and PVD) questions

  1. When silicon films are deposited by thermally decomposing silane, what kind of film forms if the deposition temperature is lowered?
  2. Which is an example of a typical material deposited by ALD?
  3. What is the main purpose of a sputtering method that ionizes sputtered atoms and draws them vertically onto the wafer with a bias?
  4. In deposition and etching equipment, which mechanism holds the wafer on the stage by electrostatic force?
  5. Which pair of source gases is used to deposit silicon nitride (Si3N4) by thermal CVD?