Hi Sungjin,
For wet etching, using a higher hardbake temperature will usually
improve the linewidth control and photoresist adhesion to the underlayer,
assuming HMDS has already been used to promote adhesion. But you may need
to use O2 plasma to strip the resist afterwards because it is highly
crosslinked.
For dry etching, CF4 + O2 plasma may erode your resist more
quickly because O2 is used to ash resist. CHF3 will improve selectivity
and anisotropy for sure. SF6 is a fast and isotropic etchant, at least at
room temp. etching. But you may try Ar + SF6 or Ar + CF4 with high Ar
ratio, besides CHF3. Good luck on your process.
Yours sincerely,
Isaac Chan
Ph.D. Candidate
Dept. Electrical & Computer Engineering
University of Waterloo
200 University Ave. W
Waterloo, Ontario, Canada
N2L 3G1
Tel: (519) 729-6409, ext. 6014
Fax: (519) 746-6321
iwchan@venus.uwaterloo.ca
http://www.ece.uwaterloo.ca/~a-sidic
On Tue, 15 Jul 2003, Sungjun Lee wrote:
> Dear all:
>
> MEMS is not my major but I need to do a simple process.
> Recently, I have worked SiO2 etching using a PMMA etch mask(100nm thickness).
> My goal is to etch SiO2 about 400A depth.(There should be PMMA alive for the
lift-off process)
> About 300nm is the width of lines written by e-beam lithography.
>
> In wet etching with 25:1 HF, I failed to get some good results.
> (PMMA was peeled off at around 120 seconds, and the etch depth is less than
100A during this time)
> Does anyone who use my condition in wet etching?
>
> We have a Oxford Etcher(plasmalab 80+).
> The 100nm-PMMA is nearly wiped-out in my conditions:
> CF4(40sccm) + O2(5sccm) under 50mtorr, 50W for 90 seconds.
> Now, I can use some other gases, Ar, SF6, and CHF3.
> Is there someone who try to other conditions?
>
> Could you please give your invaluable comments to me?
>
> Thanks in advance.
>
> Sungjun / Graduate Student.
>
>
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