Hello,
I need to etch both shallow and deep features using Deep Reactive Ion Etching.
The first etch step is fine. However, during the second etch step, deep
trenches develop at the edges of the features produced during the first etch.
I am not sure what this is due to but I think the photoresist (Shipley 9260)
spin-coated after the first DRIE etch coats the edges only very thinly and is
removed during the second etch step.

Any suggestions on how to overcome this will be greatly appreciated. Thanks.

Regards,
Melissa