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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.</div>
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Howard Northfield
<div class="ContentPasted0">Research Associate</div>
University of Ottawa<br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> labnetwork <labnetwork-bounces@mtl.mit.edu> on behalf of Mcolisi Dlamini <mcolisi_dlamini@sfu.ca><br>
<b>Sent:</b> Tuesday, November 22, 2022 7:01 PM<br>
<b>To:</b> labnetwork@mtl.mit.edu <labnetwork@mtl.mit.edu><br>
<b>Subject:</b> [labnetwork] Aluminum contamination concerns in PVD</font>
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<div style="font-size:9pt; font-family:'calibri'; color:#FF4233"><b>Attention : courriel externe | external email</b></div>
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<span style="font-size:11pt; color:black; font-family:Arial,Helvetica,sans-serif">Dear lab network:</span></p>
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<font face="Arial, Helvetica, sans-serif"><span style="font-size:11pt">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 </span></font><font face="Arial, Helvetica, sans-serif"><span style="font-size:11pt">and is </span></font><font face="Arial, Helvetica, sans-serif"><span style="font-size:11pt">currently
qualified to </span><span style="font-size:14.6667px">evaporate</span><span style="font-size:11pt"> Au, Ti, Pd, and Pt on the e-beam hearth and only Cr has been used so far on the thermal source.</span></font></p>
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<span style="font-size:12.0pt; color:black"><span style="font-family:Arial,Helvetica,sans-serif; font-size:11pt"> </span></span></p>
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<span style="font-size:11pt; color:black; font-family:Arial,Helvetica,sans-serif">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. </span></p>
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<span style="font-size:12.0pt; color:black"><span style="font-family:Arial,Helvetica,sans-serif; font-size:11pt"> </span></span></p>
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<span style="font-size:12.0pt; color:black"><span style="font-family:Arial,Helvetica,sans-serif; font-size:11pt">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: </span><a href="https://mtl.mit.edu/pipermail/labnetwork/2015-June/001867.html" target="_blank" id="LPlnk476711" title="https://mtl.mit.edu/pipermail/labnetwork/2015-June/001867.html
Ctrl+Click or tap to follow the link"><span style="color:blue; font-family:Arial,Helvetica,sans-serif; font-size:11pt">https://mtl.mit.edu/pipermail/labnetwork/2015-June/001867.html</span></a><span style="font-family:Arial,Helvetica,sans-serif; font-size:11pt">). 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.</span></span></p>
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<span style="font-size:12.0pt; color:black"><span style="font-family:Arial,Helvetica,sans-serif; font-size:11pt"> </span></span></p>
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<span style="font-size:11pt; color:black; font-family:Arial,Helvetica,sans-serif">We will appreciate your insights on this topic specific to Al contamination as well as contamination in metal evaporators in general.</span></p>
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<span style="font-size:12.0pt; color:black"><span style="font-family:Arial,Helvetica,sans-serif; font-size:11pt"> </span></span></p>
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<span style="font-size:11pt; color:black; font-family:Arial,Helvetica,sans-serif">Thank you,</span></p>
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<span style="font-size:11pt; color:black; font-family:Arial,Helvetica,sans-serif">-Mcolisi</span></p>
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<p><span style="font-family:Calibri,Helvetica,sans-serif; font-size:10pt"><span style="font-size:11pt"><b><span style="font-family:Calibri,Helvetica,sans-serif; font-size:11pt; color:rgb(117,123,128)">Mcolisi Dlamini</span></b></span></span></p>
<span style="color:rgb(117,123,128)"></span><span style="font-family:Calibri,Helvetica,sans-serif; font-size:11pt"></span><span style="font-family:Helvetica,Arial,sans-serif"></span><span style="font-family:Calibri,Helvetica,sans-serif; font-size:11pt"></span><span style="color:rgb(117,123,128)"></span>
<p><a href="http://www.4dlabs.ca" class="x_OWAAutoLink" id="LPNoLP"><span style="font-family:Calibri,Helvetica,sans-serif; font-size:11pt; color:rgb(117,123,128)">4D LABS</span></a></p>
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<p><span style="font-family:Calibri,Helvetica,sans-serif; font-size:11pt; color:rgb(117,123,128)">Simon Fraser University</span></p>
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<p><span style="font-family:Calibri,Helvetica,sans-serif; font-size:11pt; color:rgb(117,123,128)">P: 778.782.9322</span></p>
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