Process and Information Document
#A-111
Cleanroom Facility, Liquid Crystal Institute, Kent State University, Kent, Ohio
Photoresist Develop
This procedure uses the photolithography wet bench.
The photolithography wet bench is located in the Cleanroom Class 1000 South area.
The bench requires house exhaust for operation.
The wet bench/hood is our primary line of defense for removing volatile and hazardous
chemicals/vapors from our cleanroom working environment. The hoods draw a large
amount of air out of the facility. When the hoods are not is use, there is no reason to
draw this treated air (thermal, humidity, particle; expensive) out of the facility to be
wasted. So when not in use the hood faces should be closed. Also, the hoods will not
remove volatiles fast enough if work is not performed in the hood. Therefore, chemical
washing, acid etching, ect., should not be done anywhere but in the hood, i.e., not on
table tops throughout the room. Not only is this hazardous to your well being, but it is
hazardous to the equipment of the room. Acid vapors cause corrosion of steel tables and
equipment and volatile organic solvents can cause the deterioration of susceptible
materials used for air filtration, the flooring, etc.
Gloves and safety glasses must always be worn while in the cleanroom. Safety glasses
and gloves must also be worn by anyone standing around you, watching you or doing
unrelated work. Regular gloves (latex, nitrile) are sufficient to protect your hands from
the normal cleaning solvents (water, IPA), but have varying degrees of effectiveness for
other solvents (acetone, NMP). Gloves offer adequate protection as long as they are
intact. Pinholes develop in gloves in storage and therefore, the official facility policy is
to wear two pair of gloves. If one pair has a hole it will be unlikely that the other one will
as well. This is most important for acid etch procedures and not as much so for solvent
washing procedures.
Developer chemical is amine based. It must not be dumped down the drain. After use,
developer chemical should be collected in waste developer containers and sealed. This
chemical is also sensitive to air and will eventually become pH neutralized by CO2.
Therefore, developer chemical must be sealed when not in use and its functionality will
decrease over time upon continued exposure to air.
The essence of using the developer chemical is as follows:
1. Pour an amount of developer chemical into a shallow glass tray, sufficient to hold
and cover the substrate.
2. Submerge the substrate into the chemical and gently agitate.
3.
4.
5.
6.
Remove the substrate after the appropriate time interval and rinse with water.
Evaluate the substrate to make sure the desired outcome has been reached.
Proceed directly to the etching process without further cleaning.
Note: If there is not enough time to finish etching, substrates can be blown dry
with compressed gas and stored. Do not attempt to clean them at this point or the
remaining photoresist will be ruined by solvents.
The above information is intended to give a general overview of the process and not
enough information has been given for anyone to use the developer chemical without
additional formal training and certification. Should you need to do pattern developing,
please request formal training for the use of this machine from facility staff. Training
sessions are scheduled as staff have time and you may have to wait a week or so until a
time slot can be created and to allow for multiple users desiring the same training to be
assembled into a group.
Only Cleanroom Staff are allowed to train users on the use of cleanroom facility
equipment and processes. Please do not ask others in the department, your company or in
your research group to assist you to avoid formal training and certification. If training is
given by unendorsed individuals, both the trainer and trainee will lose cleanroom use
privileges for a period of time deemed appropriate by facility staff.