We came to some issue that unconclusive.
Taping relog due to same defect as prev case, photo taken - Pattern distorted at dice edges. Peding investigation and pulled commonality.
No common tool for wets side. Only common tool is Washing1.
Verified the 2 lots, only 1 wfr each affected. Batching feedback another 2 lots similar defect, bth detected at Mask. All seen with straight line "stain" defect under macro view localised from 1oadlock to wafer center, 1 wfr per lot only.
Previous also another lot 1 wfr similar defect inked off by diff. Our prev lot inked off also similar defect and location thus tats y they hold for us.
Also checked AW5P4 similar defect (now at backlap), prev at Mask. CTT on hold for masking but was waived by diffusion
When inspected under scope, defect affecting at base opening like chem seep thru, base pattern not distorted. Suspect could be resist not adhere properly at base opening area, like sc b4 mask base
Commonality points to IP01 but no correlation to defect type. Mask/Etch/tube all diff tools. Checked with diff, 1st ox measure 1 wfr post thickness at slot 1 for both center/source.
Estar shows no abnormality/interference. Wfrs running flat down, if susp stain dripping, it shld not be coincidentally at the same particular area, most prob like prev stain issue, patchy
Also the current lots no AVI scan at base level. No agreement from diff/mask. Pls help to send email for the 4 lots and relog to 1st owner. Keep device,and MQA in
copy
All the affected wafer 69 wafers but our tool ran many product.but so far no other product affected. Discuss with masking engr,and pls relog to 1st owner.
