An Advanced Method Of Polysilicon Hard Mask Wet Etch

In the process of semiconductor manufactory, the particle attached on wafer surface is always one of the important elements impacting the yield of wafer. During SiON hard mask layer wet removing process after polysilicon etching, hot phosphoric acid easily induces surface particle. The remained particle easily induces failure of next process so much as circuit contact opening and makes a transistor glitch.It focuses on the mechanisms of the particle’s formation during SiON hard mask layer wet removing process, and provides the root cause of particle’s formation. The reason is because of the stickiness of remained phosphoric acid after hot phosphoric acid wet process. Besides, it expatiates on different types of cleaning method for particle issue, then brings forwards 3 different solutions by physical aspects and chemical aspects, and gives the best way to solve particle issue after hot phosphoric wet etching by means of detail experiment data. The best way includes HF clean step, H3PO4 clean step, dryer step and SC1 clean step. The SC1 clean step is executed between H3PO4 clean step and dry step. Particle can be removed before forming condense defect on its surface by using the advanced way to remove SiON hard mask layer. Furthermore, the surface of wafer performs negative characteristic after dipping into SC1 chemical solution, it can prevent particle re-depositing on wafer as a result of electrostatic exclusion function. The final experimental result indicates it can reduce average 30% amounts of particle on the each wafer and 30% failure rate of particle accordingly, thereby, the advanced way can improve the yield of wafers greatly, and it provides theory basis and practice gist for the semiconductor factories.