I don't know what is on you Si, but I dry etch Si in SF6 @ 5mT in a RIE at
70 watts with a 4min/um rate.  Resist will never withstand a 4um etch in my
experience and wet etching that deep will not be easy.

Brent

Shweta Humad wrote:

> Hi all,
> I was thinking of a process which would involve a last step of HF wet
> etching to create 4 micron deep trenches in silicon. I'm not sure how
> long the photo resist can withstand the HF. The photo resist would be
> Shipley 1813. I could use BOE also instead of HF but that would take
> even longer. Has anyone does this before?
>
> Thank you
> --
> Shweta Humad
> Office: (404) 385-4306/2400
>
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