Moshe,

We have successfully used PECVD Silicon Carbide as a hard mask for KOH
etching. This film is also relatively unaffected by HF. I recommend you try
PECVD SiC deposition on your glass plate, pattern with photoresist, dry etch
the SiC with a CF4 plasma, then strip the photoresist. Your plate should now
be ready for HF etch.

Best Regards,

Pat Kayatta
Rogue Valley Microdevices
943 Automation Way, Suite F
Medford, Or. 97504
(541) 774-1901
(541) 774-1904 Fax
(541) 951-8027 Cell
[email protected]


-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Morten Aaroe
Sent: Friday, March 06, 2009 3:18 AM
To: [email protected]; General MEMS discussion
Subject: Re: [mems-talk] Looking for mask to make holes in glass


I think wet etching is remarkably difficult in this case, as you are not
really talking about mask stripping. What is happening, in my opinion,
is simply that the HF etches the glass away, that was bound to the mask.
Improving mask adhesion will not help in this case. Also, HF has a
remarkable ability to get into small crevices - which is why you have to
clean the oxide away before depositing your masking material, even when
etching Si wafers. This is at least my experience. I'm guessing it is
because of the large diffusivity of HF, but I have no theoretical
background to back that up.

// Morten

Moshe wrote:
> Thank you for all the answers
> I prefer to focus on a way to made holes with wet etch.
> I there a resist so the HF do not strip it ?
> As I said I tried gold and polysilicon and the HF strip it.