Polyimide solvents are flammable requiring careful management of fire safety risks. The following are the considerations and how they are resolved in actual tool use and manufacture.
Limit fuel availability
Use maximum 3 gallon stainless steel canisters to store fluids.
Use only two solvents for complete process if at all possible. Solvent develop and rinse can do double duty as ebr and back side rinse
No more than 5% of the weight of the entire tool should be of flammable material. May be achieved by using CPVC and/or metallic construction and covers.
Contain and confine fuel (solvent)
Use stainless steel or braided armored tubing in all pressurized (up stream of dispense valve) solvent lines
Provide secondary containment for dispense canisters that is of sufficient volume to contain all of the solvent in the associated canister.
Provide secondary containment at process modules
Provide exhaust to the chemical storage cabinet, the spin cup, the spin module and the hot plates. All exhausts are monitored to the EMO circuit of the tool.
Prevent combustion (reducing the concentration of Oxygen in the risk ambient obviates the possibility of combustion)
Nitrogen inert the spin cup exhaust (continuous bleed of Nitrogen to the spin cup.
Nitrogen inert the hot plate exhaust (CDA to the softbake modules for process requirement but inert the downstream exhaust from the hot plate)
Nitrogen inert the chemical cabinet (continuous bleed of Nitrogen to the chemical cabinet
If after all of the foregoing it is thought necessary (though FM does not require it) to provide fire suppression there are two means of doing so. Marine type fire suppression, which is very inexpensive but effective or CO2 type which is very expensive but effective. We recommend the Marine type.