Point of Use Particle Removal – Keeping the Ductwork Clear
Van Gompel, Joe
Some semiconductor deposition process tools generate significant quantities of solids in the form of nonvolatile particulate. Finer particulate (<10 microns) behaves more like a gas and less like a solid in the exhaust stream. This fine particulate is very difficult to remove using conventional abatement devices such as a wet scrubber, ulitmately leading to a clay-like buildup in the ductwork and in the rooftop scrubber. This problem is exacerbated with higher flows of silane and other deposition gases in 300-mm fabs. Conversely, such fine particulate responds well to electrostatic removal. A point of use (POU) wet electrostatic precipitator has been developed and was shown to remove fine particulate very effectively. The electrostatic precipitator follows the existing abatement device to intercept fugitive solids before they enter the ductwork. Customer tests on a high-silane poly deposition process have shown solids removal levels of > 99% by weight based on solids entering the electrostatic precipitator from the POU scrubber. In addition to silica, the electrostatic precipitator would be very effective at removing arsenic oxides and P2O5 from compound semiconductor exhaust streams, replacing HEPA stacks after POU devices on these applications. The electrostatic precipitator can either piggyback onto an existing POU device, sharing resources (eliminating additional water costs), or it can be installed as a standalone device following the already-installed POU scrubber.
[abstract as .pdf]