Deposition (CVD and PVD)
What is the main reason many deposition processes are carried out in vacuum equipment?
- ATo make the wafer lighter
- BTo reduce equipment noise
- CTo prevent impurities from entering the film and unwanted collisions between source particles and gas molecules
Show answer and explanation
Answer: C. To prevent impurities from entering the film and unwanted collisions between source particles and gas molecules
Air contains oxygen, moisture and particles that contaminate or oxidize the film. In sputtering and evaporation, atoms in flight that collide with gas molecules have trouble reaching the substrate. Many depositions are therefore done in vacuum or low-pressure equipment.
- A. It is unrelated to wafer weight.
- B. It is not done to reduce noise.
- C. Correct. It prevents contamination and unwanted collisions.