Deposition (CVD and PVD)

Which correctly describes silicon nitride deposited by plasma CVD?

  1. AIt contains relatively much hydrogen and tends to be less dense than thermal CVD film
  2. BIt is perfectly stoichiometric (Si3N4) and contains no hydrogen
  3. CIt conducts electricity like a metal
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Answer: A. It contains relatively much hydrogen and tends to be less dense than thermal CVD film

Plasma CVD silicon nitride is formed by reacting silane, ammonia and the like at low temperatures of about 300 to 400 °C, so it contains much hydrogen in the form of Si-H and N-H. It therefore tends to be less dense and etch faster than thermal CVD film. It is used, for example, as a protective (passivation) layer.

  • A. Correct. It contains much hydrogen and is less dense.
  • B. Being deposited at low temperature, it contains hydrogen and its composition deviates easily.
  • C. Silicon nitride is an insulator.
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More Deposition (CVD and PVD) questions

  1. When filling a narrow trench by deposition, what problem tends to occur if film builds up thickly near the trench opening (overhang)?
  2. What is the purpose of placing a plate with many holes (a collimator) between the target and wafer in a sputtering system?
  3. In PVD such as sputtering and evaporation, why is it hard to coat the sidewalls and bottoms of deep trenches?
  4. What is it called when a gas containing a dopant such as phosphorus is flowed during LPCVD polysilicon deposition to make a conductive film?
  5. Before filling contact holes with tungsten by CVD, what is the main reason a thin film such as TiN (titanium nitride) is deposited underneath?