Comment pquest SNF 2007-11-13 16:21:29: re: odd etch results

tdo at tdo at
Tue Nov 13 16:21:31 PST 2007

the cause of the previous etch problems (low rate, bad morphology) was due to problems related to the RF power supply and tuning system (not the ECR/microwave).  after several test runs, the problem did repeat itself several times: low RF power (7 W instead of 44W), all of it reflected.  the automatic tuning system thus could not tune (uncertain if this is a power supply problem, tuning system problem, or both).  
the problems were very unpredictable-- some recipes worked, others did not at times.
now the system is working as expected and rf power is normal (after 3 normal runs).   if any other users notice similar problems, please report.   an obvious sign is a DC bias value that is abnormal (in my GaAs recipe should be ~ -60V, when misbehaving it was -4 V).  Keep an eye on RF power values during etches.  

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