Yu,

There are more variables at play in the final etch rate of a sputtered
silicon nitride film than deposition rate (for example, the target can
be silicon or silicon nitride).
We used BOE etch rate as one of our metrics for a sputtered nitride film
and changed parameters to achieve the lowest etch rate possible which was
on the order of 5-10 nm/min, much worse than LPCVD nitride, which does
have the slowest etch rate.

If you are doing process design I would recommend finding a source for
LPCVD nitride, if you can work it into your process flow. If you require
a low temperature sputtered process, then by optimizing your processes I
think you can achieve better than 15:1 selectivity.

Rob




Hi,

I want to release my LTO (deposited by LPCVD) sacrificial layer uisng
BHF/BOE. Previous posts said that the selectivity is good over LPCVD silicon
nitride, but bad over PECVD silicon nitride. I would like to know its
selectivity over silicon nitride sputterred at room temperature and a rate
of ~1.5nm/min.

Any answer will be appreciated.

Thanks,

Yu Wang