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One bad thing about production line over 24/7 is problem never rest even on weekend. We have these problems as example:
Line issue over weekend:
2 lots seen with lifting at alignment pattern only. Inspected die seen with slightly higher undercut but no lifting. WB8B ER: 1494A/min within control. All wafers affected. Discussed with mask engineer Juce, already advance hold at incoming mask USG for them to try to align as he cannot gauge now if can align or not. Common tool from Cell8, no downtime yet.
Lots already reached and informed G3 mask engineer. To follow up with her to check alignment. Informed Pudin to help check if any misalignment issue.
Done mask, no alignment issue feedback by masking engr. Lot was proceeded to etch, and hold after due to random oxide residue across wafer. Did not trigger adv hold at incoming.
Already asked to bake+ipc lot pls follow to try re-etch .Already advance hold this product at incoming to add IPC step. After IPC, etched both lots 30s but after etch inspect only mildly improved, still have random residue
N+ OX RSD/LIFTING
Aft N+, whole lot seen with ox rsd localised at lower LHS/RHS edge. Also seen with similar lifting on alignment as previous 2 lots.
Extracted commonality. Common tool is CELL8. Lot etched in day, ER :1552A/min. etch time is 9min20s.
Refer to excel summary. To hold the lot first pending discussion with masking. Do not re-etch 1st.
Advance hold this pdt at N+ move in to inspect incoming and sample 1pc. If similar issue seen, to send another 1pc for remask+std etch
Operator hold for LM25 due to suspect Au OverEtch. Refer to photos. Seen whole lot affected, affecting LHS/RHS edge. Crown/flat ok.
Buddy lot in 1B no similar issue. Lot done in GS1. No mc down during running of this lot. Inspected 100%, not all wafers affected. Affected wfrs: #25/22/21/20/17/16/14/12/11/10/9/7/6/5/3 affecting the RHS edges only, not severe as prev lot.
The die saw pattern OverEtch for this lot is milder than prev lot. Commonality, GC1, for affected lot, no downtime for MRC. At Etch wet gold, 3rd run aft change sol
Buddy runs in MRC all terminated w/o hold. Lot was baked 5hrs after oven. see line is practising flat 90deg at AuTa etch
Started to map but if based on the die saw, only LM25 is have reject, the rest of the affected wafers, the die saw pattern still "curved". Pls verify further