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Hi all,</div>
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We use TDMAH in our Fiji G2 and have not had delivery issues though we do keep the cylinder at elevated temps when idle.</div>
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Is there a separate ALD group mail or just an informal mailing list? Please add me, if so!</div>
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Thanks,</div>
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Frank</div>
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<span style="color: rgb(0, 0, 0);">Frank S. Flack</span></p>
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<span style="color: rgb(0, 0, 0);">University of Wisconsin Centers for Nanoscale Technology</span></p>
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<span style="color: rgb(0, 0, 0);">Rm. 3120 Engineering Centers Bldg.</span></p>
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<span style="color: rgb(0, 0, 0);">1550 Engineering Drive</span></p>
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<span style="color: rgb(0, 0, 0);">Madison, WI 53706</span></p>
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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 Martin, Michael <michael.martin@louisville.edu><br>
<b>Sent:</b> Tuesday, August 18, 2026 4:35 PM<br>
<b>To:</b> Network Fab <labnetwork@mtl.mit.edu><br>
<b>Cc:</b> Stefan Myhajlenko <myhajlenko@asu.edu>; dleber <dleber@vt.edu>; Yu <ywu387@gatech.edu>; a-dhote <a-dhote@northwestern.edu>; Chen, Zhi D. <zhi.chen@uky.edu>; Gary <gary.spinner@ien.gatech.edu>; Bill Mitchell <mitchell@ece.ucsb.edu>; Morris, JD <james.morris.3@louisville.edu>;
Tony Whipple <whipp003@umn.edu><br>
<b>Subject:</b> [labnetwork] Some info on HfO2 precursors</font>
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Hi Labnetwork: </div>
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I wanted to summarize some advice from our informal ALD working group (formerly NNCI ALD group I think) about HfO2 precursors so that this info will be in the labnet archive and available in the Labnetwork chatbot. </div>
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"I see there are something like 4 Hf precursors that folks have used in the literature. </div>
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TEMAHf (Tetrakis(ethylmethylamido)hafnium(IV),(EtMeN)4Hf) </div>
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Tris(dimethylamido)cyclopentadienyl Hafnium, HfCp(NMe2)3 (HyALD)</div>
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Tetrakis(dimethylamido)hafnium(IV) [TDMAH]</div>
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And a chlorinated Hf compound. </div>
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We have some limited experience with TDMAH but Beneq suggests TEMAHf or HyALD is more stable. What is your go-to Hf precursor? " </div>
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Tony Whiple from Minnesota pointed out that they:</div>
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"use Tetrakis(dimethylamido)hafnium(IV) [TDMAH] in all of our ALD systems, Savannah, Lesker, Fiji. We continue to keep with the same precursors as users have set processes for that. </div>
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We have had a few issues with using this, mainly the random end of service of the precursor.<br>
The causes of the cylinder going bad ( not able to pulse material, while the cylinder is only half empty ) can at times be assigned to the cylinder heat being turned off and going to room temperature. After reheating to the correct temperature, there is a
chance the cylinder will go bad. We have had this happen only a few times. To keep this from happening, we avoid having the cylinders cool off." </div>
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Evidently others (Mac from Harvard and Bangzhi from PSU) have had similar problems with TDMAH- incidentally this is a big problem with the SnO2 precursor TDMASn. Mac suggests loading only a small amount of TDMAH at a time, and Bangzhi suggested that sometimes
cycling the manual valve to the bottle may free up the delivery line. </div>
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My inclination based on this advice is to try the <span style="color:rgb(0,0,0)">
TEMAHf (Tetrakis(ethylmethylamido)hafnium(IV),(EtMeN)4Hf) option given that we may not have super high throughput so a stable precursor might be important in our case and Beneq has provided a starting recipe. Generally, my impression is that the chlorinated
precursors can cause problems with the plumbing and pumps since the reaction yields HCl . </span></div>
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I'd love to hear any other advice people may want to share on this process and precursors. </div>
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<p style="direction:ltr; margin-top:0px; margin-bottom:0px"><span style="font-family:Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">Regards,</span></p>
<p style="direction:ltr; margin-top:0px; margin-bottom:0px"><span style="font-family:Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)"> Michael Martin, Ph.D.</span></p>
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<p style="direction:ltr; margin-top:0px; margin-bottom:0px">Manager, <span style="font-family:Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
Micro/Nano Technology Center</span></p>
<p style="direction:ltr; margin-top:0px; margin-bottom:0px"><span style="font-family:Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">University of Louisville</span></p>
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