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It is important to recognize that photolithography processes and materials vary greatly from one manufacturer to another, and therefore a customized solution may be required. Several factors are important in selecting the appropriate photoresist filter of which contaminant removal, differential pressure, flow rate, material compatibility, cartridge extractables, membrane wettability, and filter lifetime are some of the most important.
A small amount of gel particles can normally be found in photoresists. These gels can form during the manufacturing and storage of photoresists. Their removal from photoresists is highly dependent on differential pressure across the filtration system. Since, these gels are deformable they can extrude through a filter at high differential pressures. At low differential pressures, the forces that would deform gel particles are lower; therefore they are not extruded through the membrane. CUNO has been able to maximize filtration surface area to assure a low inlet pressure to the pump/dispense system as well as a low filter differential pressure, which is optimal for gel removal. The increase in filtration surface area is achieved by utilizing CUNO's patented Advanced Pleat Technology™.
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