Deposition (CVD and PVD)

What is it called when a gas containing a dopant such as phosphorus is flowed during LPCVD polysilicon deposition to make a conductive film?

  1. AIn-situ doping
  2. BIon implantation
  3. CThermal oxidation
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Answer: A. In-situ doping

Flowing a dopant gas during deposition so the impurity is incorporated as the film grows is called in-situ doping. It removes the need to introduce impurities afterward by implantation or diffusion and makes it easier to dope films uniformly even inside deep trenches.

  • A. Correct. The impurity is incorporated during deposition.
  • B. Ion implantation introduces impurities after deposition.
  • C. Thermal oxidation forms an oxide film.
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More Deposition (CVD and PVD) questions

  1. Before filling contact holes with tungsten by CVD, what is the main reason a thin film such as TiN (titanium nitride) is deposited underneath?
  2. What is the main purpose of "densification", a high-temperature anneal after depositing oxide by low-temperature CVD or similar?
  3. In ALD, what is the temperature range called in which self-limiting surface reactions keep the thickness per cycle constant?
  4. Which is an advantage of sputtering over vacuum evaporation?
  5. Which type of CVD reactor heats only the stage holding the wafer while keeping the reactor walls cool?