Problem pquest SNF 2008-09-08 22:33:12: high temp RF problem

tdo at tdo at
Mon Sep 8 22:33:12 PDT 2008

I tried to run a high temp recipe (50C chuck temp), and observed low DC bias was far too low (-3.4V).  Did not continue etch.  RF forward power and reverse power was normal (43W / 1W).   Also noticed the same low bias (-2V) on an oxygen clean recipe.  
I lowered the chuck temperature (13C) and ran the same etch conditions (on a different wafer) and the DC bias was relatively normal (-46.4V), and the etch rate and morphology turned out as expected. 
Reloaded first wafer, increased temperature again -- saw low DC bias again.  This time kept the same wafer in and lowered temperature to 18C.  DC bias was low for a few seconds, than increased back to normal.  

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