Hello,

In my experience CHF3 is a good gas to use for silicon dioxide etching.
Under the correct conditions the vertical profile is good and
selectivity to both photoresist and PMMA is high (sometimes > 4:1).

However changing the gas might solve the problem but it does not explain
why when using CF4 as the tech gas the oxide is removed in patches. I'm
afraid on that subject I dont have any answers.

Good luck!

James

renil kumar wrote:
> Hi all,
>
>                 I am using RIE for pattern transfer on SiO2 hard mask with
CF4. It seems the oxide is getting removed in patches, not at all uniform. what
would be the best recipe for removing exposed oxide with better selectivity to
PMMA  photoresist. Thanks in advance.
>
> Renil

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Dr. James Paul Grant
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