[labnetwork] Aluminum contamination concerns in PVD

[Howard Northfield]

We use Al regularly in our Angstrom LPVD system.  As a rule we cover with foil any other open crucibles in the evaporator. We actually foil cover the whole inside of the system and change it every 6 months.

Howard Northfield
Research Associate
University of Ottawa

________________________________
From: labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Mcolisi Dlamini <mcolisi_dlamini at sfu.ca>
Sent: Tuesday, November 22, 2022 7:01 PM
To: labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>
Subject: [labnetwork] Aluminum contamination concerns in PVD

Attention : courriel externe | external email

Dear lab network:



We are wondering if there are any contamination issues (or potential contamination) from adding and evaporating aluminum in our PVD system. We understand that there will be physical contamination from flakes and metal buildup. However, we are not sure whether Al will contaminate and affect other deposition processes. Our PVD is non-CMOS clean grade and is currently qualified to evaporate Au, Ti, Pd, and Pt on the e-beam hearth and only Cr has been used so far on the thermal source.



The key question we have is whether aluminum has a risk of contaminating the tool and affecting other processes? Our PVD is used for basic metallization needs including for lift-off and IC chip fabrication.



We reviewed previous exchanges on this network but they mostly focused on gold contamination in vacuum systems. Notably they do emphasize that tools should be classified based on cleanliness, eg. CMOS clean, semi-clean and the Au friendly category. This is something we will definitely keep in mind moving forward. (Gold contamination lab network thread: https://mtl.mit.edu/pipermail/labnetwork/2015-June/001867.html). Additionally, there is mention of Aluminum carbide contamination when Al is evaporated via e-beam, but we gathered that this can be mitigated by evaporating at relatively low powers.



We will appreciate your insights on this topic specific to Al contamination as well as contamination in metal evaporators in general.



Thank you,

-Mcolisi



Mcolisi Dlamini

4D LABS<http://www.4dlabs.ca>

Simon Fraser University

P: 778.782.9322
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