high selective etching of SiO2 over SiN

Hi Labmembers,

 

I need to etch SiO2 film without affecting the SiN layer underneath. I wonder if you know any recipe that has highly etching selectivity of SiO2 to SiN. By the way, both oxide and nitride layers are deposited by PECVD. Thanks in advance!

 

Thanks,

Yuan