PLEASE PLEASE help with STS etcher footing problem

[Elvis Der-Song Lin]

Hi my knowledgeable and experienced friends,

 

My groupmember and I have a question regarding methods to minimize the
footing problem when using the STS ether to etch trenches with oxide as etch
stop.  I used the "deep" recipe to etch 120 um deep trenches which are 10 um
wide.  I did about 5 minutes of over etching.  After etching, the footing
was very severe, especially at places where two trenches cross etch other.
The footing was at least 5 um on each side.  Is there a recipe that is tuned
to miniminze the "footing" problem?  Any suggestions will be high
appreciated!

 

-Elvis

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