Problem lampoly SNF 2009-02-22 07:33:03: Etch rate problem

mtang at mtang at
Tue Feb 24 16:59:39 PST 2009

raneeyoo and chingmei both reported higher than usual etch rates on chips.  I ran an etch rate test (standard recipe 1, with 60 sec main etch, 30 sec overetch) and found the following:
Si etch depth:  4618 A, 1.1% uniformity
Selectivity to resist:  4.2X
This is perhaps less than 5% higher than what we normally see.  
The etch rate was run after 10 dummy wafers were run -- and it may be me, but it seemed the plasma got less pink with the HBr (which is slightly pink anyway) as more wafers were run....
Also, ran chamber leak rate:  0.49 mt/min
And checked gas flows -- all well within spec (less than 5% deviation of full scale.)
Sorry, there does not seem to be an obvious cause of reported etch rate issues.

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