Mask Design Issues

Question 1

Steps For Photolithography

Answer 1

1. Start with clean wafer spin-coated with photoresist
2. Apply a photomask to define the features
3. Use a mask aligner to pass UV light through the mask to the wafer
4. The exposed photoresist is washed away, unexposed resist remains
5. Etch away exposed section either using wet or dry etch. The unexposed are protected by the photoresist
6. Remove all photoresist to leave perfectly etched features.

Question 2

How do you fabricate a silicon photonic circuit?

Answer 2

The first step is photolithography: photoresist is spun on the wafer, mask is applied with UV light. Then the wafer is put into a developer to remove the exposed parts of the photoresist. Then your circuits are etched. After that the photoresist is removed and then silicon dioxide deposited by PECVD. After that the wafer is diced and chips cleaned.