Comment lampoly SNF 2010-10-06 17:56:25: RF tolerance error problem

mtang at mtang at
Wed Oct 6 17:56:25 PDT 2010

According to Jae, he observed an RF tolerance error on several of his dummy wafers about 100 seconds into the main etch for his recipe -- before the wafer broke.
Cesar cleaned up the broken wafer and ran dummies.  He found that the VAT pressure controller had lost communication with the system.  Once he reset that, he ran wafers using Jane recipe #28 and found the same RF error.  He ran recipe #1 and found the problem consistently in Step 7.  Interestingly, the RF tuned in very nicely in all etch steps, but in step 7, the reflected power would jump from zero to nearly 250 W after about 10 seconds.  
Playing around with different recipes and etch times, a loadlock leak has been ruled out, but there is possibly something wrong with the stability of the VAT control.  Cesar tried reteaching the system, but the problem is still there.  He is planning to take apart the VAT valve tomorrow.

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