In plasma etching of high-aspect-ratio patterns, which phenomenon has electrons blocked by sidewalls so negative charge builds at the top of the pattern while positive ions are deflected at the bottom, causing profile defects and damage?

Answer: A. The electron shading effect

Electrons move in random directions and have trouble entering deep into narrow patterns, so negative charge builds on the upper sidewalls. Ions arrive vertically and charge the bottom positively. This charge imbalance deflects subsequent ions, causing notching and gate insulator damage.

• A. Correct. Electrons are shaded, creating a charge imbalance.
• B. The tunnel effect is a quantum phenomenon of passing through a barrier.
• C. The piezoelectric effect relates force and charge in piezoelectric materials.