[labnetwork] Light filtering in photolithography bays

Wed Mar 4 20:50:38 EST 2026

Hi Deon,

I found the UV filters photobleached with time and became less effective.

After my initial inquiry a few years ago, my end solution was to go with a native amber LED.  This is as opposed to more typical phosphor-converted LED, which uses a blue LED to excite a phosphor that emits orange.  I didn't want to deal with the "maybes" and "what-ifs" of having white/blue light anywhere in the system.  With a native amber LED, I can know with absolute certainty that lab members' resist woes are not due to the lights.

These native amber fixtures were semi-custom, at least in my form factor, but several vendors were willing to quote the work.  We ended up paying $38k for 140 fixtures, which included spares in case a few die over the next 20 years.  I realize that's more expensive, but so are failed processes!  Averaged over 20 years, it's only $2k/y.  Not bad.

Fab techs/engineers complained for a day or two about the lighting being "more orange," similar to folks in Ana's lab, but they quickly got used it and forgot that there was a color difference from the old lights (white LEDs with filters).  We've been very happy with the result.

Best,
Travis

From: Collins, Deon <deonc69 at illinois.edu>
Sent: Wednesday, March 4, 2026 2:16 PM
To: Cohen, Ana N CTR USARMY DEVCOM ARL (USA) <ana.n.cohen.ctr at army.mil>; labnetwork at mtl.mit.edu; Massey, Travis <massey21 at llnl.gov>
Subject: Re: Re: [labnetwork] Light filtering in photolithography bays

Revisiting this older post.

HMNTL has T-8's currently with UV filters.

Before I pull the trigger on filtered LED replacements, I want to make an inquiry. I am contemplating purchasing nonfiltered LEDs and reusing the UV filters from our CFL bulbs. Being we have 8 photolithography labs; initial conservative savings look to be around $5000.

Superbrightleds T8BDA-30K18A-30PK at 568.50 for a 30 pack
Vs Superbrightleds T8U4-SW5C22-F-25PK at 199.99 for a 25 pack

Thanks in advance.

Deon D. Collins

Director of Facilities

The Grainger College Of Engineering UIUC
Holonyak Micro & Nanotechnology Lab
208 N Wright St Rm. 1114 | MC-249
Urbana, IL 61801
217-300-7531 | deonc69 at illinois.edu<mailto:deonc69 at illinois.edu>

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________________________________
From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> on behalf of Cohen, Ana N CTR USARMY DEVCOM ARL (USA) <ana.n.cohen.ctr at army.mil<mailto:ana.n.cohen.ctr at army.mil>>
Sent: Friday, February 17, 2023 9:55 AM
To: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu> <labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>>; massey21 at llnl.gov<mailto:massey21 at llnl.gov> <massey21 at llnl.gov<mailto:massey21 at llnl.gov>>
Subject: Re: [labnetwork] Light filtering in photolithography bays

Hi Travis,

A couple years ago we switched our lithography bay fluorescents (T8) to
amber tube LEDS from Super Bright LEDs. The light is more orange than yellow
so took a little adjusting (many users first thought it was darker than
usual), but visibility has actually been much better since we these bulbs
are more stable and we don't end up with dark patches from dead
fluorescents.
https://www.superbrightleds.com/t8-uv-blocking-led-tube-clean-room-18w-1800-<https://urldefense.us/v3/__https:/www.superbrightleds.com/t8-uv-blocking-led-tube-clean-room-18w-1800-__;!!G2kpM7uM-TzIFchu!248iO78McTq49lWLpgFtmXickcg8iXevKK83UTDVii_LuGwhySm-zcgYhVTdUgSb8BhPOaR5CpAYu0MVbCEHIA$>
lumens-single-end-dual-end-ballast-bypass-type-b-32w-equivalent-1800k+packam
t-30-Pack

Our fume hoods are still fluorescent bulbs with filters. I've definitely
noticed a degredation over time, but our facilities also have purchased
different filters over the years, so I can't provide much comparison to your
situation. However, it may be that your LEDS are emitting higher wavelengths
than the fluorescents. UV Process has UV filters along with the color tubes
which could be useful
https://www.uvprocess.com/c3/1790-gamtube-and-supertube-filters.html<https://urldefense.us/v3/__https:/www.uvprocess.com/c3/1790-gamtube-and-supertube-filters.html__;!!G2kpM7uM-TzIFchu!248iO78McTq49lWLpgFtmXickcg8iXevKK83UTDVii_LuGwhySm-zcgYhVTdUgSb8BhPOaR5CpAYu0OKBX3hFQ$>

We don't filter our computer screens because don't notice much light
pollution and we don't keep anything photosensitive nearby long-term, but
you can definitely turn down the brightness and blue saturation on the
monitors. We also have not needed to replace the darker pigment filters on
our doors' windows, but similar to the monitors they are placed sufficiently
distant from the photoresists/coated substrates.

Good luck!
Ana

--
Ana N. Cohen [she/her/hers]
Photolithography Cleanroom Technician
Contractor | General Technical Services, LLC
US Army Research Laboratory
2800 Powder Mill Road, Adelphi, MD 20783
Tel: 301-394-1527
Email: ana.n.cohen.ctr at army.mil<mailto:ana.n.cohen.ctr at army.mil>
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