Hi,

        Our research group is also working on TFTs. We use silicon nitride
for dielectric. We have no problem with both BHF wet etching or RIE dry
etching. But I think RIE is better in cleaning native oxide on Cr because
of ion bombardment. CF4 or SF6 should work.


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) 888-4567, ext. 6014
Fax: (519) 746-6321
[email protected]
http://www.ece.uwaterloo.ca/~a-sidic


On Fri, 6 Feb 2004, Paolo Tassini wrote:

> Hi everyone!
> We are doing two metallization layers to connect a matrix of polysilicon TFTs.
> We did first a chromium deposition and patterning, then we deposited PECVD
silicon oxide,
> etched via-holes through oxide with BHF and in the end another chromium layer.
> When we tried to do some electrical measurements we found out that everything
was isolated!
> We discovered that wet etching of silicon oxide on top of chromium turns this
one into
> chromium oxide, which is insulating and very hard to scratch.
> Please, does anyone know how to remove this layer of chromium oxide?
> We would like to recover this circuit somehow!
> We can do wet and dry etching (CF4, NF3, Ar RIE, O2, H2)
> Thank you very much in advance!
>
> Ing. Paolo Tassini
> Centro Ricerche ENEA
> Via Vecchio Macello, s.n.c.
> 80055    Portici    (NA)    Italy
> tel. +39 081 7723289
> fax +39 081 7723344
> e-mail [email protected]
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