[labnetwork] Fluorescent Lamp Replacement with LED lamps in the Cleanroom?

Fri Sep 25 19:01:38 EDT 2015

Coming not long ago from an LED manufacturer

Mercury “Fluorescent” lamps use mercury excitation with familiar excitation
spectrum with peaks at G, H and I lines
http://zeiss-campus.magnet.fsu.edu/articles/lightsources/images/mercurylamps
figure1.jpg.  Phosphors are applied to absorb this light and re-emit at
target color spectra and can be rated in color temperature.

LED lamps use a blue LED, typically with  emission spectra in the 430 –
460nm range, with phosphors absorption and re-emission.  The phosphor blend
and application scheme is designed to meet target fluorescence and cost
criteria and also are rated in color temperature: 2700K  & 3000K (warm),
4500K, 6500K (cool).  The excitation blue light is typically not all
absorbed by the phosphors or there would be low efficiency, hence there is a
emission spectra local peak at the blue excitation wavelength.  The epi
design to emit at wavelengths shorter than ~430nm suffers from low
efficiency and is economically unviable unless those wavelengths are desired
in the product.

So, if your resist is not sensitive below ~430nm, unwanted
exposure/desensitization is unlikely.

Dan Pulver

MIT Lincoln Lab

From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu]
On Behalf Of Ida Noddeland
Sent: Wednesday, September 23, 2015 2:49 AM
To: Noah Clay; Tribble, Thomas A.
Cc: labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Fluorescent Lamp Replacement with LED lamps in the
Cleanroom?

We do not have LED in our cleanroom, but I have heard that it is difficult
to see thickness fringes in this kind of light. Another cleanroom (Electrum
in Stockholm) installed LED in their EBL area, but had to reinstall some
“normal” light sources after requests from the operators.

Best regards,

Ida Noddeland

Head of Laboratory

NTNU NanoLab

Sem Sælands vei 14, K1-123

7491 Trondheim

+47 41288808

 <http://www.ntnu.no/nanolab> www.ntnu.no/nanolab

From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu]
On Behalf Of Noah Clay
Sent: Tuesday, September 22, 2015 11:52 PM
To: Tribble, Thomas A.
Cc: labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Fluorescent Lamp Replacement with LED lamps in the
Cleanroom?

Tom,

We use LED strip lights (3M, I believe) in our wet benches from Reynolds
Tech.  As far as I know, they install LED lighting circuits in all of their
new bench builds and I recommend speaking with Vince Reynolds for further
information.  The lighting in our lithography benches have yellow filters on
them and have posed no issues with our research community.  For the time
being, the overhead cleanroom lighting at Penn is fluorescent.

Thanks,

Noah

Quattrone Nanofabrication Facility

University of Pennsylvania

Philadelphia, PA

On Sep 22, 2015, at 2:30 PM, Tribble, Thomas A. <tribble at fas.harvard.edu>
wrote:

The replacement of T-8 and T-5 fluorescent lamps outside the cleanroom is
becoming an increasingly popular Facilities practice.  Has there been any
experience with this kind of retrofit inside the cleanroom? Specifically, in
Lithography and other UV sensitive areas of the cleanroom, have there been
any observed (or anticipated) adverse effects from the use of LED lamps?

Thanks . . . Tom

Thomas A Tribble PE, JD | Northwest 102.32 | 52 Oxford Street | Cambridge,
MA 02138 | (tel) 617 495 0990 |(cell) 617 780 5685 |

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