Can Al corrosion occur with just water during rel?

Guest

Is it possible for aluminum corrosion to occur without the presence of contaminants (such as P or Cl) during rel tests such as autoclave or H3TRB? And does this make any difference whether the device is biased or not biased. Sometimes we found Al corrosion after H3TRB, but there are no contaminants such as P or Cl on EDX (only oxygen located).

Would appreciate your reply.

Thanks.

Joined: 20 Jun 2026 Posts: 76

Hi Curious,

Yes, you need ionic contaminants with your moisture to get the oxidation/reduction activities that will corrode your metal. You don't need a lot of Cl ions to corrode your Al lines, so this is one reason why you don't always see Cl during EDX analysis of affected parts. I suggest that you look at the ionic contam readings of water samples from your chambers.

On the next question, yes, bias affects the tendency of a metal to corrode. Corrosion mechanisms involve potential thresholds that can easily be affected by application of bias. This is why you sometimes encounter a device that's not corroding if it is not under bias, but suddenly corroding under bias.

Thanks,
FARel Engr

Guest

Hello FARel Engr,

Thank you for your reply. My main question is whether it is possible for Al corrosion to occur in H3TRB rel without the presence of ionic contaminants. Specifically I am asking is can an Al corrosion phenomenon be triggered by just water ingression into the package and electrical bias supplied to the device--without the presence of any ionic contaminants. Package delamination was observed using C-SAM but we could not find any trace of Cl under EDX.

Rgds.

Guest

jst want to share my thoughts with you guys. i read somewhere that even though al is an 'active' metal, it doesnt corrode easily. the oxide formed when it reacts with oxygen protects its surface well. so in real life maybe you really need some ions to make Al corrode. i say real life because no matter how hard you try, you cant get pure water. even di water has conductivity. besides, I also read somewhere that pure water cant help corrosion coz its not conductive.

fence sitter

Guest

Hello fence-sitters,

Thank you for sharing your thoughts. Specifically I am interested to know whether the Al corrosion can be sustained without the presence of Cl contaminants. Al can probably react with water to form Al(OH)3. The Al will also probably react with H2O and OH to form some form of Aluminum oxide (under bias--electrolysis?). But as you said the oxide formed will probably prevent further reaction. So, without any ionic contaminants to act as catalysts, can the corrosion be sustained in this case? This is what I am wondering. Can Al corrosion be triggered and sustained mainly by water and bias. We have pretty drastic corrosion after H3TRB, but we cannot find any presence of ionic contaminants under EDX. EE mentioned that only a trace amount of Cl is needed to trigger the Al corrosion; maybe this is what is happening.

Rgds.

Posted: Thu Mar 11, 2026 11:30 am Post subject:

EDX just could identify % level of contamination. If we want to identify ppb to ppt level's ion contamination , we may use IC(Ion chromatography).

Posted: Thu Mar 11, 2026 5:34 pm Post subject:

Guest,

Thank you. I think you are right. However, in our company, there's this one person who things she knows it all. We can't learn the EDX because ayaw nya ipagamit. Para namang kung sino to. Anyway, di namin alam ba't lumalaki ang ulo nya.

Thanks again. We'll just find other means to use the EDX without being frowned at and shouted at. Ang hirap talaga pag may kasama kang matandang mataba.

Thanks,
Mas Curious

Posted: Wed Mar 24, 2026 4:08 pm Post subject:

Hi Mas Curious:
I can't understand your message very well.
Recently we have a experiment about the source of Al corrision in our Fab.
We extract the wafer surface with DI water and then analysis by IC,
We found the corrision wafer have the high F, SO4 and NH4 content.(Cl content without obvious abnormal.)
And we spike the SO4 and NH4Cl to wafer surface , the wafer soon enhance corrision.
If we put the wafer in the environment of H2SO4 and NH4OH, the wafer also enhance corrision soonly.
I think the enhancement of corrision may caused by contaminat (F, Cl, SO4, NH4OH) etc and moisture.
If we want to find the resource of corrision, maybe we could detect the corriosion position directly with low detection limit chemical analsysi tool,
Maybe we can find the root cause.