The Etching of Silicon Nitride in Phosphoric Acid with Novel Single Wafer Processor

Traditionally, wafer cleaning via the batch type in semiconductor manufacturing has been used for many years. And the single wafer processor has developed for the advantage in particle control by preventing the pollution from accumulated materials. Although single wafer processor can overcome the particle and defect problem in conventional wet station, silicon nitride removal by phosphoric acid still uses the bench type tool even other processes including RCA cleaning has been changed to the single wafer tool in advanced technology. One of the reasons is the selectivity of silicon nitride to oxide. In this work, fundamental studies on the etching rate, uniformity, and selectivity were investigated by a general process tuning knobs in the single wafer processor, such as the rotation speed, puddle time, temperature, etc., which brought us a deeper understanding on the relationship of silicon nitride etching rate to the phosphoric acid.