[labnetwork] Low-stress Sputtered Ir

[Matthew Oonk]

Hello all
We are having difficulty getting a low-stress (less than +/- 200MPA)
sputtered Ir film here for a couple of users.

-It's a batch-to-batch variability so the first Ir wafer can vary between
-100 and >1000MPA for the first wafer and then films are consistently that
same stress wafer-to-wafer when we run 5 wafer batches.  (There is a small
first wafer affect but not anywhere near the run-to-run magnitude shifts.)

-We start with similar base pressure and we have tried pre-coating the
chamber with Ti and running Ir burn-in but the large batch-to-batch stress
variability persists.

-We run low-stress similar metals such as Ti, W, Ta, TiW  on the same tool
with consistent stress and these all respond typically to pressure and
power changes as well.

-The vendor has very little insight.

-The Ir film stress changes as expected with pressure, power and bias. So
we could run the film now by measuring the first wafer stress and then
adjusting the bias but this burns thru target and makes the runs more
likely to flake out on the shielding.


Does anybody run sputtered Ir with consistent stress?   Any insight as to
what else we could try?

Thanks for any information
 -Matt

Matthew Oonk
Research Engineer
Lurie Nanofabrication Facility
University of Michigan
734-646-1275
mwoonk at umich.edu
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