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<p class="MsoNormal">Hi Mario,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We use PI-2600 (2610 and 2611) extensively with Ti-Pt and Ti-Au metallization (sputtered). Films are 2 um and 5 um, respectively.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Recipes and procedures are often tailored to specific toolsets and projects, so let’s start higher level with some general thoughts:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<ol style="margin-top:0in" start="1" type="a">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">I suggest a vacuum dehydration bake before each film deposition – so, before the polyimide and again before the metal. We use our polyimide oven for this. The dehydration bake before
metal dep has had a marked impact on our metal adhesion.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">Are you imizing your polyimide at >350 C under an inert (N2) atmosphere? We do 375C because nothing in our stack is that temperature sensitive. Occasionally our oven crashes before
reaching 375C and I’ve seen bubbles beneath the metal and other issues down the line. I’ve heard of some people curing the polyimide at lower temperatures, and while you can drive off all the solvent and get a mechanically stable film, the imidization may
be incomplete.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">Our process deviates from the datasheet on the softbake. We softbake for 10 minutes at 95C (so, lower temp for longer time). This is unusually cool for NMP drive-off, but the process
has worked for our team since long before I arrived. If your films are thicker, you may need to increase one parameter or the other.<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">Does your polyimide curing oven get used for organics other than polyimide?<o:p></o:p></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1">I avoid adhesion promoters between Si and PI unless it’s strictly necessary (and it’s generally not, for my processes). I view it as another variable and possible contaminant down
the line – this contamination possibility is why I bring it up here. That said, others in my facility have used adhesion promoters for polyimide on glass without issue… but it’s good to reduce variables where you can.<o:p></o:p></li></ol>
<p class="MsoListParagraph"><o:p> </o:p></p>
<p class="MsoNormal">I’m happy to discuss further if you have additional questions/issues or want a detailed procedure.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best,<o:p></o:p></p>
<p class="MsoNormal">Travis Massey<o:p></o:p></p>
<p class="MsoNormal">Lawrence Livermore National Laboratory<o:p></o:p></p>
<p class="MsoNormal">7000 East Avenue, Livermore, CA 94550<o:p></o:p></p>
<p class="MsoNormal">925-422-9509 (desk)<o:p></o:p></p>
<p class="MsoNormal">925-495-7103 (work cell)<o:p></o:p></p>
<p class="MsoNormal"><a href="mailto:massey21@llnl.gov">massey21@llnl.gov</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> labnetwork <labnetwork-bounces@mtl.mit.edu> <b>
On Behalf Of </b>Beaudoin, Mario<br>
<b>Sent:</b> Wednesday, February 1, 2023 11:08 AM<br>
<b>To:</b> labnetwork@mtl.mit.edu<br>
<b>Subject:</b> [labnetwork] Question: adhesion of metal to BPDA/PPD polyimide<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p>Dear Networkers,<o:p></o:p></p>
<p>I'm new to polyimide processing. We have a student project that requires deposition of metal on polyimide (BPDA/PPD PI-2600 series from HD microsystems). We tried liftoff with depositon of Ti/Pt by Ebeam. Despite a 1min O2 plasma, albeit at low power,
the metal was peeling off. Moreover, the photoresist was also peeling off from the polyimide. Does anyone have a good working recipe for metalization of polyimide?<o:p></o:p></p>
<p>Thanks,<o:p></o:p></p>
<p>Mario<o:p></o:p></p>
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