Overview
After photolithography defines a pattern in the photoresist, etching is used to physically remove the unprotected material, leaving behind the desired circuit structures.
Types of Etching
- Wet Etching: Uses liquid chemicals to dissolve material; typically isotropic (removes material in all directions).
- Dry Etching (Plasma Etching): Uses reactive gases or ions; can be highly anisotropic (removes material in a specific direction), which is essential for creating vertical features.
- Atomic Layer Etching (ALE): A highly precise method that removes material one atomic layer at a time.
Role in Fabrication
Etching is repeated many times during the manufacturing process to build up the complex 3D structures of modern transistors and interconnects.