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US 5,114,447 AGranted
Ultra-high efficiency porous metal filter
AssigneeMott Metallurgical Corporation
InventorChristopher B. Davis
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AssigneeMott Metallurgical Corporation
InventorChristopher B. Davis
Estimating the term…
An ultra-high efficiency particulate air filter for use in the microelectronics manufacturing industry is formed as a fully homogeneous sintered metal filter that exhibits an efficiency substantially in excess of a 6 log reduction and preferably equal to or exceeding a 9 log reduction (an efficiency of 99.9999999%). The filter can be used as a process gas in-line filter in state of the art gas supply systems. The porous metal filter exhibits long term stability relative to mechanical or thermal stress and operates within the desired ultra-high efficiency levels even under high pressure conditions. It does not exhibit an outgassing problem and there is no particle shedding. These features are provided within a unit no larger than those conventionally employed heretofore with organic membranes and under substantially identical operating conditions.
An ultra-high efficiency particulate air filter for use in filtering process gases for the semiconductor and microelectronics manufacturing industries comprising a filter element made from porous sintered metal, said element having a filtration efficiency relative to its most penetrating particle size of at least 6 log reduction and a specific surface per unit area of at least 0.055 m.sup.2 /cm.sup.2 when standardized to a thickness of 0.068 inch, said filtration efficiency being measured at a flow rate of 30 SLPM for an 11.3 in..sup.2 filter area.
An ultra-high efficiency particulate air filter comprising a filter element of porous sintered metal powder having a presintered mean particle size substantially less than 20 microns and a sintered density of at least 5 g/cc., the filter element having been sintered to a degree sufficient to hold the metal powder permanently in position and less than would cause reduction in filtration efficiency below 99.9999%.
Dependencies are inferred from the claim text.