Si3N4 Etching with Carboxylic-Acid-Containing Superheated Water

A selective Si 3 N 4 etching is required in the semiconductor manufacturing process. In general, Si 3 N 4 was selectively etched to SiO 2 in hot H 3 PO 4 . However, since the existing Si 3 N 4 etching process used a high-temperature and high-concentration acid solution, environment, health, and safety issues may occur. In this study, a new Si 3 N 4 etching process based on superheated water was studied. In superheated water, Si 3 N 4 was etched, but also Si and SiO 2 were etched, making it difficult to apply to actual Si 3 N 4 etching process. By adding carboxylic acid to superheated water, Si 3 N 4 was selectively etched without material loss of Si and SiO 2 in a Si 3 N 4 /SiO 2 repeated stack structure. The Si 3 N 4 etching process using superheated water with addition of carboxylic acid is an eco-friendly, safe and new etching process that can solve various problems that may occur in the existing H 3 PO 4 process.