Deep Trenches Cleanliness Challenges for CMOS Image Sensors

摘要

Selective silicon nitride film etching are still performed in wet benches with hot orthophosphoric acid. Several drawbacks from such process are presented with various ionic contaminations in high aspect ratio features. Moreover, a correlation is done between these contaminations and CMOS Image sensors device failure. Finally, several process alternatives are given as solutions to replace the phosphoric wet benches.