Lithography
What is the main purpose of the bottom anti-reflective coating (BARC) applied under resist?
- ATo speed up etching
- BTo suppress standing waves in the resist and dimensional variation caused by reflection from the underlying layers
- CTo bond the resist to the wafer
Show answer and explanation
Answer: B. To suppress standing waves in the resist and dimensional variation caused by reflection from the underlying layers
When exposure light passes through the resist and reflects from underlying layers, it interferes with the incoming light, creating standing waves in the resist, and topography in the underlying layers causes dimensional variation. BARC suppresses reflection from below and improves dimensional accuracy.