It seems that Cr is sputtered and re-deposited during the oxide etched causing
roughness across the wafer. The effect is quite evident if a large portion of
the wafer is masked with Cr. You can probably minimised it by leaving a large
an area as you can unmasked and if you are using photoresist to pattern the
Cr, try to leave it on the Cr during the SiO2 etch, but make sure it doesn't
overhang the Cr mask.

Simone Capecchi
Optical Engineer
Terahertz Photonics Limited
Rosebank park
Livingston
EH54 7EJ
Tel :- 01506-818534
Fax :- 01506-818577

 -----Original Message-----
From:   lib zhou [mailto:[email protected]]
Sent:   17 July 2002 09:49
To:     [email protected]
Subject:        [mems-talk] problem of SiO2 dry etching

Dear All:

In my SiO2 etching experience with ECR model ,when I used metal Cr film as the
etching mask, the etched surface is very rough even though the self bias is
small ,when the self bias -40V approximately,the roughness nearly 500A.however
when I used metal Al film as the etching mask and through the same process,
the etch result is smooth.as in my experience,the Cr film is must be used,so I
am urgently.want to know the reason of the roughness and how to get smooth
surface with Cr mask.  Coulf you give me some information,thank you very much
ahead!

Lib zhou
Yahoo! Autos - Get free new car price quotes
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