Datasets:
srobertsphd
/
mit-labnetwork

Dataset card Data Studio Files
xet
Community
1
text
stringlengths
1
2.97k
Malcom Hathaway suggested a change in the substrate reflectivity, which is
my current hypothesis. However this seems to affect both Si and oxide,
since I see this effect on both cases, so this may be in fact a case of
chemicals sticking to the surface and not coming out even during long
piranha baths. I have AFM and other surface characterization options
planned, it is a matter of finding a good time to have it done now.
Thank you all again for the suggestions and references. I'll make sure to
post an update here if I have anything useful.
Best,
--
Gustavo de Oliveira Luiz, PhD
Applications/Research Specialist
nanoFAB, University of Alberta
On Fri, Mar 24, 2023 at 3:21?PM Hathaway, Malcolm R <
hathaway at cns.fas.harvard.edu> wrote:
> Hi Gustavo,
>
> Another thought (from a non-photo-expert, for sure!):
>
> It may be the prior photo steps are changing the reflectivity of the
> silicon (or aluminum, on Travis's samples), especially as it shows up as
> having an effect on dose. Surface roughening? A very thin chemical
> residue?
>
> Perhaps an AFM scan would be revealing...
>
>
> Mac Hathaway
> Harvard CNS
>
> ------------------------------
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> on behalf of Massey,
> Travis <massey21 at llnl.gov>
> *Sent:* Friday, March 24, 2023 2:30 PM
> *To:* Gustavo de Oliveira Luiz <deolivei at ualberta.ca>;
> labnetwork at mtl.mit.edu <labnetwork at mtl.mit.edu>
> *Subject:* Re: [labnetwork] Strange "sample memory" with LOR 5B
>
>
> Hi Gustavo,
>
>
>
> I don?t have a definitive answer for you, and I?m certainly no chemist,
> but also consider the role of AZ Developer (another base) and reactions of
> NMP with residual water or alkaline solutions.
>
>
>
> First, the pair of alkaline developers *may* actually be enough to break
> through the relatively thin oxide created by the piranha, at which point
> the bases will start attacking the silicon. Second, if this is only
> happening with LOR, it?s also possible that residual liquid (likely
> alkaline) is being trapped under the AZ 1512 then reacting with the NMP.
> Spinning may not do a great job of removing this liquid trapped beneath the
> resist overhang. I suspect a bulk attack, though, since the residual
> patterns in the wafer reflect the resist pattern itself rather than the
> perimeters of the resist patterns. I haven?t noticed this before on SiO2,
> but NMP alone ? and especially water-contaminated NMP ? can attack some
> metals (Al, Cu, etc.). This paper suggests that acidic or alkaline
> contaminants in NMP may exacerbate the problem. I see these ghosts of
> previous patterns all the time in aluminum-coated wafers I pattern and
> reuse repeatedly for process development/characterization, and I?ve
> recently started seeing it on Ti as well ? no LOR, just an assortment of
> positive resists.
>
> https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9211805
> <https://urldefense.proofpoint.com/v2/url?u=https-3A__ieeexplore.ieee.org_stamp_stamp.jsp-3Ftp-3D-26arnumber-3D9211805&d=DwMGaQ&c=WO-RGvefibhHBZq3fL85hQ&r=TEMLD8-VsxCGtcVzmvpT5GFNSczskEKHzW6aYlttmIY&m=1-k7qvkCMYMPtYpozWsK_KGAJGieHTpEbECqW_3lIM8S9M8eXG8-e5DadL6e-7pS&s=Z-bdFigBPa6X1HeTz5-YGnfzpYQPP0zbhVFxbzVW_0A&e=>
>
>
>
> Best,
>
> Travis Massey
>
> Center for Micro and Nanotechnology
>
> Lawrence Livermore National Laboratory
>
>
>
> *From:* labnetwork <labnetwork-bounces at mtl.mit.edu> * On Behalf Of *Gustavo
> de Oliveira Luiz
> *Sent:* Friday, March 24, 2023 10:37 AM
> *To:* labnetwork at mtl.mit.edu
> *Subject:* [labnetwork] Strange "sample memory" with LOR 5B
>
>
>
> Hello everyone,
>
>
>
> While working on a recipe for LOR 5B/AZ 1512 in our automatic development
> system, I encountered some intriguing effects when reusing wafers for my
> tests. This could be a problem for our users when developing their own
> process, so we'd appreciate it if anyone could help us to understand what
> is going on.
>
>