Deposition (CVD and PVD)
What is the main purpose of a sputtering method that ionizes sputtered atoms and draws them vertically onto the wafer with a bias?
- ATo improve film coverage at the bottom of deep holes and trenches (bottom coverage)
- BTo slow down deposition
- CTo change the color of the film
Show answer and explanation
Answer: A. To improve film coverage at the bottom of deep holes and trenches (bottom coverage)
In ordinary sputtering, atoms arrive from many directions, so little film reaches the bottom of deep holes. Ionizing sputtered atoms in the plasma and drawing them in vertically with a wafer bias makes it easier to deposit film at the bottom. It is used to form barrier and seed layers.