Manual beaker development in fumehood

Beaker development, in fume hood 09: UV development or fume hood 10: e-beam development, is a fall-back option if you have a process, which is not compatible with the automatic, or semi-automatic, tools. We always recommend using, or at least trying, the automatic and semi-automatic tools, instead of using manual beaker development.

Manual beaker development is necessary for some processes, but should be avoided if possible, due to the fact that it is notoriously difficult to get a stable repeatable process - especially when multiple users are sharing the same process; everybody simply does things a bit different from each other, which leads to changes in the process outcome. Some processes have a very narrow process window, which makes them inherently sensitive to small changes in the development. The manual development also has a much greater chance of producing particles, both from the operator and the environment.

Finally the safety of the operator is at a significantly higher risk, since any manual handling of chemicals carries the risk of accidental spills with it. This is especially problematic if the developer is TMAH based, where direct skin exposure of >1% TMAH on a few percent of the body must be treated as a life-threatening event.

Special rules for manual beaker development of TMAH

Automatic agitation methods are not allowed - this includes magnetic stirring or sonication
Manual agitation methods, which create large waves or turbulence in the development solution, are not allowed
Users must submit a risk assessment for any process requiring manual beaker development of TMAH based developers
Users requiring manual beaker development of TMAH based developers must additionally provide valid reasons for not using the already available automatic and semi-automatic tools

Standard manual beaker development procedure

Standard procedure for manual beaker development in fume hood:
1) Submerge exposed substrate into development solution
2) When timer ends, move substrate directly into Rinse 1
3) After a few seconds, move substrate into Rinse 2*
4) Remove developed substrate for drying
(*It is allowed to omit the Rinse 2 step)

The standard procedure for manual beaker development in a fume hood is as follows:

Prepare development process
Perform development
Clean up

Prepare development process

Write the chemical label, which must always be present in your chemical setup - your write your label before pouring the chemical
Find the beakers required for your process
Find the items required for holding/submerging your substrate during the process
Find carriers or other storage units for placing your substrate after the process has finished
Find a timer - make sure it works as you expect it to, before submerging your substrate into the development solution and discovering that the timer is in fact broken
Get some cleanroom wipes and keep them nearby, for wiping any drops spilled during handling
Do not cover too many of the exhaust holes in the fume hood table, as this will reduce the efficiency of the exhaust, which reduces safety
Do not place your beakers too close to the fume hood sash, as this can make it difficult to efficiently extract the fumes escaping from the beakers, which reduces safety

Perform development

Put on the appropriate personal protection gear
Pour rinsing agent into Rinse 1 and Rinse 2 beakers - typically DI water or IPA
Pour development solution into development beaker
Place exposed substrate in the appropriate carrier
Set timer
Submerge substrate into development beaker
Start timer immediately
When timer is 5 seconds from ending, prepare to lift the substrate out of the development beaker
Lift substrate out of development beaker - it can help to lift it at a slight angle, to allow liquids to drain more easily from large surfaces
Submerge it immediately into Rinse 1
Agitate up/down for at least a few seconds
Move substrate into Rinse 2*
Agitate slightly
The developed substrate can now be removed and dried

(*It is allowed to omit the Rinse 2 step)

Clean up

Pour Rinse 1 and Rinse 2 into appropriate waste: water goes into the sink, IPA goes into C-waste drain
Rinse beakers with the DI-water gun
Pour development solution into appropriate waste: solvent based developer goes into C-waste drain. NB! TMAH is an aqueous alkaline solution, which must never be mixed with solvents! TMAH waste goes into the dedicated TMAH waste container, stored in the chemical cabinet in E-4.
If your developer solution is not TMAH based:
- Rinse beaker 3 times, discard water into sink
If your developer solution is TMAH based:
- Rinse beaker once with DI-water and discard this into the TMAH waste
- Rinse beaker two more times, discarding the water into the sink
Hang all beakers to dry on the drying rack
Erase the chemical label text
Wipe any droplets on the fume hood surface
Discard any napkins/other trash in the bin inside the fume hood