[labnetwork] Some info on HfO2 precursors

[Gila,Brent P]

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 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> on behalf of 
> Martin, Michael <michael.martin at louisville.edu>
> *Sent:* Tuesday, August 18, 2026 4:35 PM
> *To:* Network Fab <labnetwork at mtl.mit.edu>
> *Cc:* Stefan Myhajlenko <myhajlenko at asu.edu>; dleber <dleber at vt.edu>; 
> Yu <ywu387 at gatech.edu>; a-dhote <a-dhote at northwestern.edu>; Chen, Zhi 
> D. <zhi.chen at uky.edu>; Gary <gary.spinner at ien.gatech.edu>; Bill 
> Mitchell <mitchell at ece.ucsb.edu>; Morris, JD 
> <james.morris.3 at louisville.edu>; Tony Whipple <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)
> 2.
>     Tris(dimethylamido)cyclopentadienyl Hafnium, HfCp(NMe2)3 (HyALD)
> 3.
>     Tetrakis(dimethylamido)hafnium(IV) [TDMAH]
> 4.
>     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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