[labnetwork] Some info on HfO2 precursors

Thu Aug 20 10:27:29 EDT 2026

Hello,
We use TDMAH also for our new Fiji G2 at Ohio State. We have limited data with it but so far, so good.

We have a VERY old PicoSun Sunale 150 and used a precursor from EMD/SAFC that they call HFCMMM. Chemical name is Bis(methylcyclopenta-dienyl) Methoxymethyl Hafnium. It is a solid. That PicoSun has/had a heated source made for sources like this called PicoSolid. The precursor works well when first installed but quickly changes colors and/or blocked the plumbing lines. We believe this is due to the PicoSolid itself, not necessarily the precursor. The tooling for the PicoSolid is not a bubbler or cylinder, but a set of two glass cylinders with a frit, o-ring, and ceramic spacer. The seal to the ALD is another O-ring. This tooling was intended for true research where you’d install a precursor, use it immediately, then remove it. Basically, for ALD precursor development. This is not how we used it and that caused problems. In any event, just adding this other precursor to the mix. I see no reason to continue using it now that we have the Fiji and TDMAH. But I am very interested in this issue.

Would love to be added to an ALD group if there is one.

Best,
Aimee

Aimee Bross Price
Manager, Nanofabrication
The Ohio State University
Nanotech West Lab
Institute for Materials and Manufacturing Research
1381 Kinnear Road
Suite 100
Columbus, OH 43212
614-292-2753
Price.798 at osu.edu<mailto:Price.798 at osu.edu>
Nanotech.osu.edu

Pronouns: she/her/hers

From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Gila,Brent P
Sent: Wednesday, August 19, 2026 5:20 PM
To: Frank Flack <fsflack at wisc.edu>; Martin, Michael <michael.martin at louisville.edu>; Network Fab <labnetwork at mtl.mit.edu>
Cc: Yu <ywu387 at gatech.edu>; Stefan Myhajlenko <myhajlenko at asu.edu>; dleber <dleber at vt.edu>; Morris, JD <james.morris.3 at louisville.edu>; a-dhote <a-dhote at northwestern.edu>; Chen, Zhi D. <zhi.chen at uky.edu>; Gary <gary.spinner at ien.gatech.edu>; Tony Whipple <whipp003 at umn.edu>; Bill Mitchell <mitchell at ece.ucsb.edu>
Subject: Re: [labnetwork] Some info on HfO2 precursors

We also use TDMAH in our Fiji at UF with no issues. Very reliable end of life and performance. I too would like to be added to an ALD mail group if possible. Thank you, Brent On 8/19/2026 12: 10 PM, Frank Flack wrote: [External Email] Hi all,

We also use TDMAH in our Fiji at UF with no issues.  Very reliable end of life and performance.

I too would like to be added to an ALD mail group if possible.

Thank you,
Brent

[cid:image001.png at 01DD308D.CD708BD0]

On 8/19/2026 12:10 PM, Frank Flack wrote:
[External Email]
Hi all,

We use TDMAH in our Fiji G2 and have not had delivery issues though we do keep the cylinder at elevated temps when idle.

Is there a separate ALD group mail or just an informal mailing list?  Please add me, if so!

Thanks,
Frank

Frank S. Flack

University of Wisconsin Centers for Nanoscale Technology

Rm. 3120 Engineering Centers Bldg.

1550 Engineering Drive

Madison, WI 53706

________________________________
From: labnetwork <labnetwork-bounces at mtl.mit.edu><mailto:labnetwork-bounces at mtl.mit.edu> on behalf of Martin, Michael <michael.martin at louisville.edu><mailto:michael.martin at louisville.edu>
Sent: Tuesday, August 18, 2026 4:35 PM
To: Network Fab <labnetwork at mtl.mit.edu><mailto:labnetwork at mtl.mit.edu>
Cc: Stefan Myhajlenko <myhajlenko at asu.edu><mailto:myhajlenko at asu.edu>; dleber <dleber at vt.edu><mailto:dleber at vt.edu>; Yu <ywu387 at gatech.edu><mailto:ywu387 at gatech.edu>; a-dhote <a-dhote at northwestern.edu><mailto:a-dhote at northwestern.edu>; Chen, Zhi D. <zhi.chen at uky.edu><mailto:zhi.chen at uky.edu>; Gary <gary.spinner at ien.gatech.edu><mailto:gary.spinner at ien.gatech.edu>; Bill Mitchell <mitchell at ece.ucsb.edu><mailto:mitchell at ece.ucsb.edu>; Morris, JD <james.morris.3 at louisville.edu><mailto:james.morris.3 at louisville.edu>; Tony Whipple <whipp003 at umn.edu><mailto:whipp003 at umn.edu>
Subject: [labnetwork] Some info on HfO2 precursors

Hi Labnetwork:
   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.

"I see there are something like 4 Hf precursors that folks have used in the literature.

  1.  TEMAHf   (Tetrakis(ethylmethylamido)hafnium(IV),(EtMeN)4Hf)

  1.  Tris(dimethylamido)cyclopentadienyl Hafnium, HfCp(NMe2)3 (HyALD)

  1.  Tetrakis(dimethylamido)hafnium(IV) [TDMAH]

  1.  And a chlorinated Hf compound.

We have some limited experience with TDMAH but Beneq suggests TEMAHf or HyALD is more stable.  What is your go-to Hf precursor? "

Tony Whiple from Minnesota pointed out that they:
"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.

We have had a few issues with using this, mainly the random end of service of the precursor.
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."

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.

My inclination based on this advice is to try the 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 .

I'd love to hear any other advice people may want to share on this process and precursors.

Regards,

   Michael Martin, Ph.D.

Manager, Micro/Nano Technology Center

University of Louisville
(502) 552-1945

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