I have used the S1800 series (e.g., S1822) for a short HNA etch and it was
OK.
Note that someone else on this group reported having problems with this
resist,
but used Cr+Au under the resist as a mask.
Remember that if you mix the HNA solution I reported on,
it must sit for a long time, preferably a day,
for chemical reactions to form the final etchant to be complete.
> -----Original Message-----
> From: Weili Liu [mailto:[email protected]]
> Sent: Tuesday, February 12, 2002 2:12 PM
> To: [email protected]
> Subject: Re[2]: [mems-talk] [Q] Mask for isotropic silicon wet etch?
> (fwd)
>
>
> Hello kirt,
>
> I am also trying to use HNA. I contacted with Shipley and they have
> S1818 and S1827. Will they work as HNA mask and can you
> suggest a receipt?
>
> >> I am trying to isotropically wet etch silicon using a
> >> 126:60:5 HNO3:H20:NH4F
> >> etchant (as described by Williams and Muller, J. of MEMS
> >> 1996). The etchant
> >> appears to work well, but masks made of AZ5214 do not. In
> less than
> >> 15 minutes, the AZ5214 layer has visibly thinned and formed holes.
> >>
> >> Can anyone recommend a more durable mask (PR, metal, both or
> >> otherwise) for this etchant?
>
> kac> In my measurements with this etchant the photoresist
> etch rate was zero
> kac> (or it might have even swelled slightly).
> kac> Try OCG (formerly KTI) 820 or similar in this series of resists
> kac> or
> kac> Shipley Microposit 1822 or similar in this series.
> kac> Silicon dioxide is slowly etched.
> kac> Silicon nitride is barely etched.
> kac> Titanium is etched.
> kac> Chromium is not etched.
>
> kac> --Kirt Williams Agilent Technologies
> kac> _______________________________________________
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> kac> Visit us at http://www.mems-exchange.org/
>
>
>
>
> Best regards,
> Weili mailto:[email protected]
>
> ----
> Weili Liu
> 14-124 Engineering IV
> Department of Mechanical and Aerospace Engineering
> University of California-Los Angeles
> 420 Westwood Plaza, Los Angeles, CA90095
> Tel: 310-825-7457
> Fax: 310-206-2302
> _______________________________________________
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