Deposition (CVD and PVD)

Learn the differences between CVD, PVD and ALD, sputtering and the advantages of plasma CVD through multiple-choice questions.

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Deposition (CVD and PVD): key points

Deposition creates thin films such as insulators, semiconductors and metals on the wafer. It is broadly divided into CVD, which deposits films through chemical reactions of gases, and PVD, which deposits them physically, as in sputtering and evaporation.

As devices shrink and become three-dimensional, ALD, which controls film thickness one atomic layer at a time and coats deep trenches uniformly, is becoming more important.

All Deposition (CVD and PVD) questions (50)

  1. Into which category does deposition by sputtering fall?
  2. Which is a characteristic of ALD (atomic layer deposition)?
  3. What is the main advantage of plasma CVD (PECVD)?
  4. Which correctly describes step coverage in deposition?
  5. Which deposition method is mainly used to fill trenches for copper wiring?
  6. Which is a characteristic of low-pressure CVD (LPCVD)?
  7. Which source gas is commonly used to deposit polysilicon by LPCVD?
  8. Which correctly describes vacuum evaporation?
  9. What problem tends to occur when a deposited thin film has large internal stress?
  10. What is the method called in which liquid material is dropped onto the center of a wafer and spun at high speed to form a uniform film?
  11. Which liquid organosilicon compound is widely used as a source for CVD of silicon oxide?
  12. Which gas is used as the source for tungsten CVD?
  13. Why has high-density plasma CVD (HDP-CVD) been used to fill narrow trenches with insulator?
  14. Which correctly describes uses of silicon nitride (Si3N4) films?
  15. What is the main purpose of placing magnets behind the target in magnetron sputtering?
  16. Under what condition does CVD give good step coverage (conformality)?
  17. When silicon films are deposited by thermally decomposing silane, what kind of film forms if the deposition temperature is lowered?
  18. Which is an example of a typical material deposited by ALD?
  19. What is the main purpose of a sputtering method that ionizes sputtered atoms and draws them vertically onto the wafer with a bias?
  20. In deposition and etching equipment, which mechanism holds the wafer on the stage by electrostatic force?
  21. Which pair of source gases is used to deposit silicon nitride (Si3N4) by thermal CVD?
  22. What is the method called that sputters a titanium target in a nitrogen-containing gas to form titanium nitride (TiN) films?
  23. What is an advantage of plasma-enhanced ALD (PEALD)?
  24. In CVD equipment, which component supplies source gas uniformly over the wafer through many small holes?
  25. Which deposition method fills very narrow, deep trenches from the bottom with a flowable film and then solidifies it?
  26. What is generally done to increase the deposition rate in sputtering?
  27. For films of the same material, in what way are high-temperature thermal CVD films generally better than plasma CVD films?
  28. What is the approximate film thickness deposited in one ALD cycle?
  29. What is an advantage of vacuum evaporation that heats material with an electron beam?
  30. Which technique uses differences in surface materials to grow films only in specific places?
  31. What is the most appropriate range for the thickness of thin films handled in semiconductor manufacturing?
  32. Which correctly describes the basic way an LSI is built in manufacturing?
  33. What is the main reason many deposition processes are carried out in vacuum equipment?
  34. Which deposition method has mainly been used to form aluminum wiring films?
  35. What does "sputter yield" mean in sputtering?
  36. Which correctly describes silicon nitride deposited by plasma CVD?
  37. When filling a narrow trench by deposition, what problem tends to occur if film builds up thickly near the trench opening (overhang)?
  38. What is the purpose of placing a plate with many holes (a collimator) between the target and wafer in a sputtering system?
  39. In PVD such as sputtering and evaporation, why is it hard to coat the sidewalls and bottoms of deep trenches?
  40. What is it called when a gas containing a dopant such as phosphorus is flowed during LPCVD polysilicon deposition to make a conductive film?
  41. Before filling contact holes with tungsten by CVD, what is the main reason a thin film such as TiN (titanium nitride) is deposited underneath?
  42. What is the main purpose of "densification", a high-temperature anneal after depositing oxide by low-temperature CVD or similar?
  43. In ALD, what is the temperature range called in which self-limiting surface reactions keep the thickness per cycle constant?
  44. Which is an advantage of sputtering over vacuum evaporation?
  45. Which type of CVD reactor heats only the stage holding the wafer while keeping the reactor walls cool?
  46. Which is an example of the precursors used to deposit HfO2 gate dielectrics by ALD?
  47. Which model organizes, by temperature and gas pressure, the tendency of sputtered metal films to form columnar grains with many voids at low deposition temperatures?
  48. In CVD, what is the phenomenon called in which more source gas is consumed and the deposition rate drops as the area of wafers or patterns being coated increases?
  49. In reactive sputtering, what is the phenomenon called in which, with too much reactive gas flow, the target surface becomes covered with a compound and the deposition rate drops sharply?
  50. Which method is used to tune the stress of plasma CVD silicon nitride from compressive to tensile?

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