[labnetwork] Cleanroom structure

[Fouad Karouta]

Dear Wing Leong,
It is a sensitive topic and here are some comments based on my personal
experience and it reflects my personal opinion.
First I like to say that I did experience two clean rooms, one having a
chase layout with CR and service areas in U form and one vertical structure
with a ballroom and subfab.

Pros Ballroom/Subfab:
1- better and efficient use of surface area where total ballroom area is
used for placing the tools.
2- It allows clustering the tools by functionality and possibly simplifies
the installation of services like gaslines.
3- It allows the dirty services to be installed in the subfab and not
influence the CR area (think pumps, heater/chillers, power supplies, etc
which generate particles, heat, etc).
4- Subfab can be engineered to receive a good portion of the clean air from
the ballroom which allows you to install dirty processes in the subfab and
still enjoy a certain cleanliness of the environment. Think CMP and some
wet etching processes.
5- It allows installation of high resolution EBL and SEM in the ballroom
area with the stabilizing scaffold on ground level.

Cons Ballroom/Subfab:
1- Long distance between tools and primary pumps which can be overcome by
oversizing slightly the pumps (more cost).
2- Possibly you may need to go to the subfab to check things if a process
fails.

There are possibly other cons and hopefully other reactions will come.

To be more concrete I am personally a fervent supporter of the vertical
structure. In my time at Eindhoven University of Technology, we had first a
small 150m2 clean room (chase layout) at level 8 of our building. Later a
bigger clean room was built early 2000's with an 800m2 foot-print in a
vertical structure (ballroom and subfab). The ballroom hosted a 100kV EBL
and a high resolution SEM.
At ANU we are in the process of constructing a new building with a 650m2
clean room in vertical structure.
On another note I had the opportunity to visit the HKUST NFF but the subfab
was engineered differently than the one I described above.

Hope this helps and best regards,
Fouad
Ex-Manager ANFF ACT Node at the Australian National University

On Sat, Sep 5, 2020 at 2:00 AM Wing Leong CHUNG <mfcchung at ust.hk> wrote:

> Dear all,
>
> NFF of HKUST are planning to build a new cleanroom research facility. We
> want to know the pros and cons of a vertical structure (cleanroom with
> sub-fab)? Hope can give us some valuable suggestion.
>
> May I have some examples of cleanroom with vertical structure as well.
>
> Many Thank.
> Jeff Chung
>
> Senior Manager, NFF, HKUST
> www.nff.ust.hk
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