Hello everyone,

I am looking to etch THROUGH a standard thickness wafer (about 500micron).
As a result, I am using a secondary support wafer (also 500micron thickness)

I have tried bonding the wafers prior to etch (using 7 um of SPR220-7
photoresist),
but I am not getting good heat transfer and my resist is buring very quickly...
(I am using 7-10 micron SPR220-7 as a mask as well)

If I am just etching one wafer (ie -- no secondary support wafer) I get decent
results with the same process. (but obviously I am stopping before going all the
way through the wafer....)

I have tried reducing chiller temp, but this didn't help much. I am using 30-40W
platen
during the etch and 20W platen during the passivation. I think we have a 300W
generator, so not sure how much lower I can go.

I am thinking of switching to an oxide hardmask.

1 - Does anyone have an idea of how drastically this will affect the etch
results. ?
2 - How should I compensate ? (in order to get similar results as using PR mask)

My wafers have large features mostly and about 25-30% exposed silicon.

Current process is approximately:
etch - 450sccm SF6, 20sccm O2 ---> 2200Wsource, 40W platen (6 seconds)
passivation - 200sccm C4F8 ----> 1600Wsource, 20W platen (3 seconds)

Thanks in advance for any help.

neo man
[email protected]




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