[labnetwork] Fwd: ALD of SiO2 and SiN with precursors 3DMAS and BTBAS

Thu Oct 22 17:08:11 EDT 2015

Dear Vicky,

I have just a few comments in addition to the nice overview that J from Stanford sent.

First regarding silicon precursors. We have recipes on file for 3DMAS and BTBAS for both SiNx and SiO2, and for BDEAS we also have recipes for SiO2 (and I expect this one would also work for SiNx, in many cases precursors are interchangeable to an extent in these recipes). We started in the past with 3DMAS for SiNx, but most of the recent work (in collaboration with Eindhoven University) is on BTBAS (see also attached papers from me).

Second regarding TDMAT and TiCl4. The attached paper from Brennan is also from MIT doing TiN using TDMAT on an OpAL. The mentioned silicon precursors are compatible with TDMAT. For TDMAT we did quite some work at Yatton and now the results at low temperature are comparable to those for TiCl4 (we can give that recipe as well). If they want to switch from TiCl4 to TDMAT, we would normally suggest to get a new manifold to replace the chlorine contaminated manifold. From previous experience, there is a risk that chlorine contamination could decompose other precursors which are installed on that manifold. This is the recommendation, but based on the other responses in this email chain we might be too careful. I can also imagine that something with high vapour pressure and good stability such as TMA can be on the same manifold when purging is sufficient.

Best regards,
Harm

=============================
Dr.ir. Harm Knoops (H.C.M. Knoops)
Technical Sales Specialist (ALD)
Oxford Instruments Plasma Technology
Email: harm.knoops at oxinst.com<mailto:harm.knoops at oxinst.com>
Phone: +31 6 23153483
Skype: harm.knoops_oxinst
www.oxford-instruments.com<http://www.oxford-instruments.com/>
=============================

From: WARD Craig
Sent: dinsdag 13 oktober 2015 13:49
To: KNOOPS Harm; MACKENZIE Brodie
Cc: MCQUARRIE Andrew
Subject: FW: [labnetwork] Fwd: ALD of SiO2 and SiN with precursors 3DMAS and BTBAS

Chaps,

Some general information from the same chain, J is one of the main users at Stanford.

Best Regards,

Craig Ward
US Applications Manager
Oxford Instruments America, Inc.
300 Baker Avenue, Suite 150,
Concord, MA 01742, USA
Mobile: +1 (978) 764 7023
Email: craig.ward at oxinst.com<mailto:craig.ward at oxinst.com>
http://www.oxford-instruments.com/

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From: labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu> [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of J Provine
Sent: Tuesday, October 13, 2015 11:48 AM
Cc: Labnetwork
Subject: Re: [labnetwork] Fwd: ALD of SiO2 and SiN with precursors 3DMAS and BTBAS

Hello Dr. Diadiuk,
at stanford we have worked extensively on PEALD of SiN in the last year, characterizing deposition both on the Fiji systems in the SNF and on a FlexAl in a single PI laboratory. we were particularly interested in low wet etch rate in fluorine chemistries (like HF) and electrical properties such as leakage current and dielectric constant.

successful deposition was shown to be possible with 3DMAS, BTBAS, DCS (dicholorsilane, which i highly recommend against, reasons below), and TSA (trisilylamine). by far the majority of the work we have done is on 3DMAS, which we have stocked for a long time and are familiar with since we use it for SiO2 deposition as well. there are a couple of papers coming out soon on this work.

some details about each that may be helpful for you
3DMAS - good recipes established for SiO2 and SiN. most fully characterized precursor from this list. easily obtainable from sigma aldrich and strem and gelleste. price is comparable to other metal amide precursors (TDMA-Hf and TDMA-Ti). etch rate and electrical properties of SiO2 and SiN films are both demonstrably improved over PECVD at the same temperature. GPC ~0.1A/cycle

BTBAS - new precursor to us for this SiN study. not extensively studied, but deposition definitely possible for SiO2 and SiN. GPC ~0.2A/cycle. readily available and reasonably priced from all the typical precursor suppliers

TSA - promising for SiN. we have not looked into SiO2 deposition yet. not extensively explored. GPC ~0.25A/cycle for us, but others have reported even higher (close to 1A/cycle) which we could not reproduce on the FlexAl. low wet etch rate and low leakage currents, similar to what was achieved with 3DMAS. this precursor is pretty hard to stock as we could only source it from air liquid and it look a lot of effort/time/cost to get supply to Stanford. not sure why that is.

DCS - stay away from this. hard to get in a compatible storage cylinder for ALD (much more common to come in large volumes for distribution throughout a facility). dangerous for sure. also, not at all clear that this precursor provides a self limiting surface reaction, so it does not perform ALD so much as CVD. could not achieve etch rate or electrical properties as good as seen with 3dmas and tsa, most likely because of the lack of self-limiting half reactions. since you are already using TiCl4, this may not be as much of a concern, but we've stayed away from chloride chemistries in SNF because of issues with co-deposition in the same chamber with Pt and Ru metals by ALD.

let me comment further on your specific questions:
Does anyone have any experience w/them & with TDMAT?

we also have used TDMA-Ti for our Ti precursor since we started ALD work in SNF. we have had great success with TiO2 and TiN deposition with this precursor. as i mentioned above we steered clear of TiCl4 because of HCl by products and compatibility issues since we wanted to deposition Pt and Ru in the same chamber. is it possible this is where the concern you mentioned about TiCl4 with metal amide precursors comes from? similar to the notes from the folks at notre dame, i don't see a safety issue with using these precursors on the same manifold. as an additional datapoint on this, berkeley's nanolab had TiCl4, TMA, and TDMA-Hf all in use on their picosun system.

Any recommendations or suggestions for precursors for SiO2 and SiN?

see above.

We'd like to assess all of these precursors and films with respect to:
1) Cost and availability of precursor

addressed above

2) Robustness of precursor  (A precursor that degrades rapidly over time wld not be preferred)

i didn't mention this above, but we never saw any of these decay over time. the only precursor we have stocked for a long time (meaning months to a year) to know for sure that it has good shelf life is 3DMAS. however, TSA at least is chemically stable and requires no heating for introduction into the chamber, so i would surmise it is also stable.

bonus info: TDMA-Ti is quite stable on the shelf or even heated (we keep it at 75C on the tools), and will last for months.

3) Quality of film:  Electrical data would be nice but even indices of refraction would do

because we have papers coming out soon, i've stopped short of supplying raw data, but gave a general level of results above. indices of refraction for the optimized recipes are on the order of 2.0 at 655nm for 3DMAS and TSA. closer to 1.9 at 655nm for BTBAS, and 1.8 at 655nm for DCS.

4) Any chemical compatibility issues.

nothing established in this regard. everything looks fine.

5) Existence of recipes on the Oxford ALD tool at other places.  This will reduce the amount of optimization that we will need to do.

on our FlexAl
recipes in existence for SiN and SiO2 for 3DMAS. SiN for TSA and BTBAS, and starting points for SiO2.

additionally a starting point recipe for SiO2 for BTBAS on a different reactor (Cambridge Nanotech FijI)

please feel free to contact me if you would like recipe details, and i can be in touch regarding our forthcoming papers related to this topic if you wish.

i hope this was helpful.
dr j

On Tue, Oct 13, 2015 at 6:03 AM, Mike Young <myoung6 at nd.edu<mailto:myoung6 at nd.edu>> wrote:
Hi Vicky. See below for relevant comments from two of my esteemed colleagues, regarding our FlexAL and its sources.

--Mike

Begin forwarded message:

From: Mark Richmond <Mark.M.Richmond.7 at nd.edu<mailto:Mark.M.Richmond.7 at nd.edu>>

Mike,
   I was never informed of any manifold compatibility issues of precursors by Oxford, and Dr. Xing didn't have any objections to that either. I found that odd but the system is under vacuum and is purged well before and after recipes are executed. As you can see from Dave's screen capture we have had this setup for the last few years, although we do not perform many Titanium growths.

   As for the SiO2 and SiN we use BDEAS in our recipes, Nitride growth is very slow though. We never purchased a BTBAS source but we did have a 3DMAS source. The 3DMAS source was used up in attempting to characterize the material and we never had a good material growth so we have not replaced that material. It used to be in the empty spot that is now on the machine.

   Vicky should be able to contact Oxford for their information sheets on different film recipes per precursor or I have in the past anyway.

Thanks
Mark

On Mon, Oct 12, 2015 at 2:09 PM, David Heemstra <David.Heemstra.1 at nd.edu<mailto:David.Heemstra.1 at nd.edu>> wrote:
Mike:
We also have two separate manifolds.  Below is a screen capture for our system.
Maybe im missing something but - it sounds like they don't want to put TiCl4 and TMA on the same manifold?  I believe that is how ours is currently setup.
I thought we had 3DMAS or BTBAS a long time ago - but currently Si source is BDEAS.
Possible (if we are doing something that isn't ideal) it is OK as long as you use sufficient purges afterwards?
Not really sure that this helps.  Mark may have a better understanding.
Dave

[Inline image 1]

On Sun, Oct 11, 2015 at 10:26 AM, mike young <mike.young at nd.edu<mailto:mike.young at nd.edu>> wrote:
dave/mark, can you advise Vicky regarding this ALD question?

-------- Forwarded Message --------
Subject:

[labnetwork] ALD of SiO2 and SiN with precursors 3DMAS and BTBAS

Date:

Fri, 9 Oct 2015 15:56:30 -0400

From:

Vicky Diadiuk <diadiuk at mit.edu><mailto:diadiuk at mit.edu>

To:

labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>

Hi,
 We are interested in adding SiO2 and SiN deposition capabilities to at least one of our ALD systems (specifically the Oxford FlexAL).
The system has two sets of independent precursor manifolds.
Currently, one manifold is completely filled up with TMA, the Hf source and the W source, while the second manifold only has TiCl4 for depositing TiN and TiO2.
The problem is that the TiCl4 source (and other such metal halide sources) is not compatible with metal amide sources and thus we can't put any metal amide precursors on the two open slots on the second precursor manifold.

Our users are interested in depositing SiO2 and SiN by using metal amide precursors like 3DMAS and BTBAS but that requires that the TiCl4 source be replaced with a compatible Ti precursor, such as TDMAT to deposit TiN.
The precursors we are considering based on what people seem to be using at other universities and a quick literature search are:

SiO2
3DMAS/TDMAS
BTBAS
SiN
3DMAS
Does anyone have any experience w/them & with TDMAT?
Any recommendations or suggestions for precursors for SiO2 and SiN?

We'd like to assess all of these precursors and films with respect to:
1) Cost and availability of precursor
2) Robustness of precursor  (A precursor that degrades rapidly over time wld not be preferred)
3) Quality of film:  Electrical data would be nice but even indices of refraction would do
4) Any chemical compatibility issues.
5) Existence of recipes on the Oxford ALD tool at other places.  This will reduce the amount of optimization that we will need to do.

We really appreciate any comments you might have.
Thx,
 Vicky

--
Michael P. Young                                (574) 631-3268<tel:%28574%29%20631-3268> (office)
Nanofabrication Specialist                      (574) 631-4393<tel:%28574%29%20631-4393> (fax)
Department of Electrical Engineering            (765) 637-6302<tel:%28765%29%20637-6302> (cell)
University of Notre Dame                         mike.young at nd.edu<mailto:mike.young at nd.edu>
B-38 Stinson-Remick Hall
Notre Dame, IN 46556-5637

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