durusmail: mems-talk: Questions regarding HMDS (Hexamethyldisilazane)
Questions regarding HMDS (Hexamethyldisilazane)
2013-11-22
Sk Fahad Chowdhury
2013-12-16
Gianmario Scotti
2013-12-16
Bill Moffat
2013-12-16
Daniel Figura
2013-12-17
Andrew Sarangan
2013-12-17
Nathan McCorkle
FW: Questions regarding HMDS (Hexamethyldisilazane)
2013-12-17
Bill Moffat
Questions regarding HMDS (Hexamethyldisilazane)
2013-12-20
Nathan McCorkle
2013-12-20
Bill Moffat
Questions regarding HMDS (Hexamethyldisilazane)
Andrew Sarangan
2013-12-17
My experience is exactly as you have stated. I am not a chemist, but I
have not seen evidence that HMDS priming improves the resist adhesion.
The real advantage comes from the hydrophobic surface preventing polar
liquids from penetrating the resist/substrate interface, which
determines how well the resist pattern will survive the wet
development. In fact, photoresist will bead up and refuse to spin coat
on an excessively primed substrate, which would suggest that the
adhesion is actually poorer on a primed surface. So it is a delicate
balance between hydrophobic and hydrophilic effects. Too little
priming will make the photoresist stick better, but it will make the
water stick even better, so all your small features will float away.
Too much priming will make the resist unable to form a film.

Interestingly, all of this has been well studied in a paper from 1984.
The conclusion of the paper reads
"In fact, the HMDS is sold as an “adhesion promoter,‘” Contrary to
this, this study revealed that  the same treatment made photoresist to
substrate adhesion drastically weaker, as demonstrated in the Dry
Adhesion Test. From this point  of view,  HMDS cannot be referred to
as an “adhesion promoter,” This inconsistency has been resolved by two
different adhesion mechanisms proposed here"

Here is the reference to that paper:
http://dx.doi.org/10.1016/0166-6622(84)80153-5



On Mon, Dec 16, 2013 at 5:26 PM, Daniel Figura
 wrote:
> Hello Bill and all,
>
> one question in regards to HMDS I was wondering about - does HMDS actually
> increase the adhesion in mechanical sense or only due to higher
> hydrophobicty prevents water and developer penetration between photo resist
> and substrate and prevents the delamination that way.
>
> In other words, if I would do a dry cross-cutter peel test, would I measure
> higher adhesion on HMDS primed wafers than on untreated?
>
> Thanks.
>
> With best regards,
>
> Daniel
>
>
>
> Daniel Figura
>
> smartfabgroupT Company
>
> process consulting . data processing . fab software
>
> Phone: +421 944 45 26 86
>
> E-mail: daniel.figura@smartfabgroup.com, Web: www.smartfabgroup.com
>
>
>
> Disclaimer notice: The information contained in this message and any
> attachments is intended only for the personal and confidential use of the
> designated recipient(s) named above. If you are not the intended recipient
> of this message you are hereby notified that any review, disseminitation,
> distribution or copying of this message is strictly prohibited. If you have
> received this message by error, please notify the sender immediately.
>
>
>
>
> -----Original Message-----
> From: mems-talk-bounces+daniel.figura=smartfabgroup.com@memsnet.org
> [mailto:mems-talk-bounces+daniel.figura=smartfabgroup.com@memsnet.org] On
> Behalf Of Bill Moffat
> Sent: Monday, December 16, 2013 18:18
> To: General MEMS discussion
> Subject: Re: [mems-talk] Questions regarding HMDS (Hexamethyldisilazane)
>
> Practical input from the developer of vacuum vapor prime and Silylation in
> the 80's.  HMDS has very active NH ending to the molecule which is looking
> for hydrogen, given hydrogen it quickly forms ammonia NH3, usually from
> water or hydroxyl ions. When reacting with a totally dry silicon dioxide
> surface it reacts with the hydroxyl ions and leaves a mono layer.  In This
> mono layer the molecule is now Silicon with 3 methyl atoms. A
> inorganic/organic molecule, a perfect adhesion for  an organic photoresist
> to adhere to an inorganic substrate Silicon. Bill Moffat
>
> Sent from my iPad
>
> On Dec 16, 2013, at 5:44 AM, "Gianmario Scotti" 
> wrote:
>
>> Hello Sk,
>>
>>
>> I am no HMDS expert, and am talking from memory, so don't take my word for
>> any of this:
>>
>>
>> 1: Yes, I believe HMDS is polar, just by looking at the molecule.
>> 2. and 3: HMDS forms a monolayer on SiO2, glass and hopefully (some)
>> metals, making the surface hydrophobic. Since we're talking of monolayers,
>> the thickness is probably below 1 nm. During sylilation by HMDS, some
>> ammonia may be produced.
>>
>> You will find more info in this reference: F. Deyhimi, J. A. Coles, Helv.
>> Chim. Acta 65, 1752 (1982)
>> Rapid Silylation of a Glass Surface: Choice of Reagent and Effect of
>> Experimental Parameters on Hydrophobicity
>> http://onlinelibrary.wiley.com/doi/10.1002/hlca.19820650610/abstract
>>
>>
>>
>>
>>
>>
>>
>> On Thu, Nov 21, 2013 at 8:17 PM, Sk Fahad Chowdhury <
>> sk.chowdhury.fahad@gmail.com> wrote:
>>
>>> Hi
>>>
>>> I have a few questions about hexamethyldisilazane or HMDS
>>> (CH3-Si-NH2-Si-CH3)
>>>
>>> 1.       1. Is HMDS a polar molecule? Is there any dipole present?
>>> electronegativity values of constituents are : H 2.2, C 2.55, Si 1.9, N
>>> 3.04. Carbon (2.55) - flourine (4) bonds are polar because of their
>>> electronegativity difference.
>>>
>>> 2.       2. How thick can HMDS on top of SiO2-Si be when it is dried in
> air
>>> from a liquid state? Can the thickness of HMDS be determined when it is
> air
>>> dried?
>>> 3. If HMDS is air dried and some molecules are left in sample, is it
> going
>>> to be HMDS molecule or it will be something else? Will it release
> ammonia?
>>> Also will it be a continuous layer or there will be clustering?
>>>
>>> Thanks a lot :)
>>>
>>> regards
>>>
>>> Sk
>>> _______________________________________________
>>> Hosted by the MEMS and Nanotechnology Exchange, the country's leading
>>> provider of MEMS and Nanotechnology design and fabrication services.
>>> Visit us at http://www.mems-exchange.org
>>>
>>> Want to advertise to this community?  See http://www.memsnet.org
>>>
>>> To unsubscribe:
>>> http://mail.mems-exchange.org/mailman/listinfo/mems-talk
>>
>>
>>
>> --
>> Gianmario Scotti
>>
>> Researcher
>> Aalto University, Dept. of Materials Science and Engineering
>> http://materials.aalto.fi/en/
>>
>> Micronova, Tietotie 3
>> 02150 Espoo
>> Finland
>> _______________________________________________
>> Hosted by the MEMS and Nanotechnology Exchange, the country's leading
>> provider of MEMS and Nanotechnology design and fabrication services.
>> Visit us at http://www.mems-exchange.org
>>
>> Want to advertise to this community?  See http://www.memsnet.org
>>
>> To unsubscribe:
>> http://mail.mems-exchange.org/mailman/listinfo/mems-talk
> _______________________________________________
> Hosted by the MEMS and Nanotechnology Exchange, the country's leading
> provider of MEMS and Nanotechnology design and fabrication services.
> Visit us at http://www.mems-exchange.org
>
> Want to advertise to this community?  See http://www.memsnet.org
>
> To unsubscribe:
> http://mail.mems-exchange.org/mailman/listinfo/mems-talk
>
> _______________________________________________
> Hosted by the MEMS and Nanotechnology Exchange, the country's leading
> provider of MEMS and Nanotechnology design and fabrication services.
> Visit us at http://www.mems-exchange.org
>
> Want to advertise to this community?  See http://www.memsnet.org
>
> To unsubscribe:
> http://mail.mems-exchange.org/mailman/listinfo/mems-talk
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
Visit us at http://www.mems-exchange.org

Want to advertise to this community?  See http://www.memsnet.org

To unsubscribe:
http://mail.mems-exchange.org/mailman/listinfo/mems-talk
reply