Use Of An Asymmetric Polysulfone Membrane Filter For The Filtration Of Liquid Corrosive Chemicals In The Electronics Industry

摘要

The filtration of chemicals used in the manufacture of semiconductor devices is essential in bulk filtration, recirculating wet bench baths and spray tools. Filtration is necessary to reduce particles to a minimum in the chemical prior to exposure to the semiconductor device. Several parameters are essential in choosing the right filter for this application. Filters must have good chemical compatibility, must be low in extractables (ions, metals, and total organic carbon), and have good flow with low pressure drop. Filters must also exhibit good particle capture and not unload particles during the life cycle of the filter. The use of highly asymmetric polysulfone membrane filters for the filtration of aggressive chemicals in semiconductor manufacturing can have several significant benefits. Polysulfone membrane is chemically resistant to a variety of common chemicals used in the manufacture of semiconductor devices. Process chemicals such as SC-1 and SC-2 chemistries, various HF concentrations, Hydrofmoroethers (HFE), and other process chemicals have been shown to be compatible with polysulfone membranes. In the case of the acid chemistries, a hydrophilic membrane is utilized. In the case of HFEs and other low surface tension organic solvents, a hydrophobic membrane is utilized. The use of asymmetric polysulfone membrane filters over traditional fluoropolymer membranes has several advantages. 1. Flow rate vs. pressure drop is significantly better for asymmetric polysulfone. PTFE membranes typically have 3-5 times the associated pressure drop when compared with the polysulfone membrane. 2. Polysulfone membranes have a higher capacity for holding and retaining particles and are not subject to particle unloading as are PTFE membranes. 3. Ionic extractables from polysulfone are at a minimum and have been independently documented as lower than those from PTFE. 4. Cost of ownership directly associated with the purchase of these filters is significantly reduced; within the range of 30-40% the cost of an all fluoropolymer filter. 5. Maintenance costs associated with filter replacement, equipment replacement (pumps) and tool downtime are additive to the polysulfone filter cost savings.