US5607647A — Air filtering within clean environments

Claim 1

Independent Claim 238 words

An air filtering system for filtering an air stream for use in a clean environment to effectively remove a process-limiting molecular contaminant therefrom comprising sequentially arranged upstream and downstream air filtering beds, said upstream air filtering bed being constructed and arranged for filtering air for use in a clean environment, being positioned to receive an air stream from the clean environment and comprising activated carbon particles in the size range of 20×140 mesh impregnated with an upstream chemically active reagent of sulfuric acid in a quantity selected to reduce the concentration of a process-limiting molecular contaminant in the air stream to a level below that which is detrimental to a process associated with the clean environment as said air stream passes through the upstream air filtering bed, said upstream chemically active reagent releasing a characteristic volatile component into said air stream at a concentration level that is detrimental to the associated clean environment process, and said downstream air filtering bed being constructed and arranged to filter air for use in a clean environment, being positioned to receive the air stream that has passed through said upstream air filtering bed and comprising activated carbon particles in the size range of 20×140 mesh impregnated with a downstream reagent selected to reduce the concentration of the characteristic volatile component released by said upstream reagent of sulfuric acid to a level below that which is detrimental to the associated clean environment process.

Claim 2

Dependent Claim 238 words

An air filtering system for filtering an air stream for use in a clean environment to effectively remove a process-limiting molecular contaminant therefrom comprising sequentially arranged upstream and downstream air filtering beds, said upstream air filtering bed being constructed and arranged for filtering air for use in a clean environment, being positioned to receive an air stream from the clean environment and comprising activated carbon particles in the size range of 20×140 mesh impregnated with an upstream chemically active reagent of sulfuric acid in a quantity selected to reduce the concentration of a process-limiting molecular contaminant in the air stream to a level below that which is detrimental to a process associated with the clean environment as said air stream passes through the upstream air filtering bed, said upstream chemically active reagent releasing a characteristic volatile component into said air stream at a concentration level that is detrimental to the associated clean environment process, and said downstream air filtering bed being constructed and arranged to filter air for use in a clean environment, being positioned to receive the air stream that has passed through said upstream air filtering bed and comprising activated carbon particles in the size range of 20×140 mesh impregnated with a downstream reagent selected to reduce the concentration of the characteristic volatile component released by said upstream reagent of sulfuric acid to a level below that which is detrimental to the associated clean environment process.

Claim 3

Dependent Claim 14 words

The air filtering system of claim 1 wherein said downstream reagent is a base.

Claim 4

Dependent Claim 23 words

The air filtering system of claim 1 wherein said sulfuric acid is impregnated on activated carbon particles at a doping level of 5-90%.

Claim 5

Dependent Claim 13 words

The air filtering system of claim 3 wherein said doping level is 20-50%.

Claim 6

Dependent Claim 17 words

The air filtering system of claim 1 wherein said downstream reagent is potassium hydroxide or potassium iodide.

Claim 7

Dependent Claim 23 words

The air filtering system of claim 5 wherein said downstream reagent is impregnated on activated carbon particles at a doping level of 5-15%.

Claim 8

Dependent Claim 61 words

The air filtering system of claim 1 wherein the air stream of the clean environment is subject to molecular contamination including airborne proton acceptors and said upstream reagent comprises sulfuric acid impregnated on an adsorbent media at a doping level selected to remove the airborne proton acceptors from the airstream as the air stream passes through said upstream air filtering bed.

Claim 9

Dependent Claim 26 words

The air filtering system of claim 1 wherein said upstream and downstream reagents are impregnated on activated carbon particles in the size range of 20×50 mesh.

Claim 10

Dependent Claim 82 words

The air filtering system of claim 1 wherein said upstream and downstream air filtering beds respectively comprise a molecular chemical filter comprising an air permeable web of non-woven fibrous carrier material of pleated form, said web comprising a matrix formed of a multiplicity of synthetic fibers and characterized in that activated carbon particles are distributed throughout said web, bound in the interstices of the matrix in a manner preventing loss to the air stream particles in quantity detrimental to the clean environment.

Claim 11

Dependent Claim 24 words

The air filtering system of claim 1 wherein said upstream and downstream air filtering beds are integrated into a common pleated non-woven carrier material.

Claim 12

Dependent Claim 39 words

The air filtering system of claim 1 further comprising an intermediate air filtering bed disposed between said upstream and downstream air filtering beds and comprising an intermediate reagent selected to remove the volatile component released by said upstream reagent.

Claim 13

Dependent Claim 39 words

The air filtering system of claim 1 further comprising an intermediate air filtering bed disposed between said upstream and downstream air filtering beds and comprising an intermediate reagent selected to remove the process-limiting molecular contaminant from said air stream.

Claim 14

Dependent Claim 28 words

The filtering system of claim 1 wherein said upstream reagent releases into the air stream said characteristic volatile component at a concentration of about 600 ppt or greater.

Claim 15

Dependent Claim 207 words

An air filtering system for filtering an air stream for use in a clean environment to effectively remove a process-limiting molecular contaminant therefrom comprising sequentially arranged upstream and downstream air filtering beds, said upstream air filtering bed being constructed and arranged for filtering air for use in a clean environment, being positioned to receive an air stream from the clean environment and comprising whetlerite to reduce the concentration of a process-limiting molecular contaminant in the air stream to a level below that which is detrimental to a process associated with the clean environment as said air stream passes through the upstream air filtering bed, said whetlerite releasing a characteristic volatile component into said air stream at a concentration level that is detrimental to the associated clean environment process, and said downstream air filtering bed being constructed and arranged to filter air for use in a clean environment, being positioned to receive the air stream that has passed through said upstream air filtering bed and comprising activated carbon particles in the size range of 20×140 mesh impregnated with downstream reagent selected to reduce the concentration of the characteristic volatile component released by said whetlerite to a level below that which is detrimental to the associated clean environment process.

Claim 16

Dependent Claim 207 words

An air filtering system for filtering an air stream for use in a clean environment to effectively remove a process-limiting molecular contaminant therefrom comprising sequentially arranged upstream and downstream air filtering beds, said upstream air filtering bed being constructed and arranged for filtering air for use in a clean environment, being positioned to receive an air stream from the clean environment and comprising whetlerite to reduce the concentration of a process-limiting molecular contaminant in the air stream to a level below that which is detrimental to a process associated with the clean environment as said air stream passes through the upstream air filtering bed, said whetlerite releasing a characteristic volatile component into said air stream at a concentration level that is detrimental to the associated clean environment process, and said downstream air filtering bed being constructed and arranged to filter air for use in a clean environment, being positioned to receive the air stream that has passed through said upstream air filtering bed and comprising activated carbon particles in the size range of 20×140 mesh impregnated with downstream reagent selected to reduce the concentration of the characteristic volatile component released by said whetlerite to a level below that which is detrimental to the associated clean environment process.

Claim 17

Dependent Claim 15 words

The air filtering system of claim 14 wherein the downstream reagent is a metal salt.

Claim 18

Dependent Claim 25 words

The air filtering system of claim 14 wherein the downstream reagent is an acid suitable for exposure to air for use in a clean environment.

Claim 19

Dependent Claim 28 words

The filtering system of claim 14 wherein said upstream reagent releases into the air stream said characteristic volatile component at a concentration of about 600 ppt or greater.

Claim 20

Dependent Claim 265 words

An air handling system for providing a filtered air stream, substantially free of a process-limiting molecular contaminant, for use in a clean environment comprising: a semiconductor device processing station that releases a process-limiting molecular contaminant into air within a clean environment; a recirculating air system for recirculating and filtering an airstream from adjacent said processing station, said recirculating air system comprising an air filtering system comprising sequentially arranged upstream and downstream air filtering beds, said upstream air filtering bed being constructed and arranged to filter air for use in a clean environment, being positioned to receive the air stream recirculated by said recirculating air system and comprising activated carbon particles in the size range of 20×140 mesh impregnated with an upstream reagent of sulfuric acid in a quantity selected to reduce the concentration of the process-limiting molecular contaminant released by said semiconductor device processing station from the air stream as the air stream passes through said upstream air filter, said upstream reagent releasing a characteristic volatile component into the air stream at a concentration level that is detrimental to the clean environment, and said downstream air filtering bed being constructed and arranged to filter air for use in a clean environment, being positioned to receive the air stream that has passed through said upstream air filtering bed and comprising activated carbon particles in the size range of 20×140 mesh impregnated with a downstream reagent selected to reduce the concentration of the characteristic volatile component released by said upstream reagent of sulfuric acid to level below that which is detrimental to the associated clean environment process.

Claim 21

Dependent Claim 265 words

An air handling system for providing a filtered air stream, substantially free of a process-limiting molecular contaminant, for use in a clean environment comprising: a semiconductor device processing station that releases a process-limiting molecular contaminant into air within a clean environment; a recirculating air system for recirculating and filtering an airstream from adjacent said processing station, said recirculating air system comprising an air filtering system comprising sequentially arranged upstream and downstream air filtering beds, said upstream air filtering bed being constructed and arranged to filter air for use in a clean environment, being positioned to receive the air stream recirculated by said recirculating air system and comprising activated carbon particles in the size range of 20×140 mesh impregnated with an upstream reagent of sulfuric acid in a quantity selected to reduce the concentration of the process-limiting molecular contaminant released by said semiconductor device processing station from the air stream as the air stream passes through said upstream air filter, said upstream reagent releasing a characteristic volatile component into the air stream at a concentration level that is detrimental to the clean environment, and said downstream air filtering bed being constructed and arranged to filter air for use in a clean environment, being positioned to receive the air stream that has passed through said upstream air filtering bed and comprising activated carbon particles in the size range of 20×140 mesh impregnated with a downstream reagent selected to reduce the concentration of the characteristic volatile component released by said upstream reagent of sulfuric acid to level below that which is detrimental to the associated clean environment process.

Claim 22

Dependent Claim 145 words

The clean environment of claim 18 further comprising a make-up air system for drawing air from an atmosphere that is subject to molecular contamination including airborne proton acceptors, said make-up air system comprising an air filtering system comprising an upstream air filtering bed positioned to receive air streams recirculated by said recirculating air system and comprising an upstream reagent selected to effectively remove airborne proton acceptors from the air stream as the air stream passes through said upstream air filter, said upstream reagent releasing a characteristic volatile component into the air stream, and a downstream air filtering bed positioned to receive the air stream that has passed through said upstream air filtering bed and comprising a downstream reagent selected to remove the characteristic volatile component released into said air stream by said upstream reagent of the upstream air filtering bed in said make-up air system.

Claim 23

Dependent Claim 28 words

The filtering system of claim 18 wherein said upstream reagent releases into the air stream said characteristic volatile component at a concentration of about 600 ppt or greater.

Claim 24

Dependent Claim 144 words

A deep UV photolithography station comprising a deep UV lithographic process tool; a recirculating air system for recirculating and filtering an airstream from adjacent said lithographic processing station, said recirculating air system comprising an air filtering system comprising an upstream air filtering bed positioned to receive the air stream recirculated by said recirculating air system and comprising activated carbon particles in the size range of 20×140 mesh impregnated with sulfuric acid for effectively removing airborne proton acceptors from the air stream as the air stream passes through said upstream air filtering bed, and a downstream air filtering bed positioned to receive the air stream that has passed through said upstream air filtering bed and comprising activated carbon particles in the size range of 20×140 mesh impregnated with a base selected to remove volatile sulfuric acid or sulfuric acid components released into said air stream.

Claim 25

Dependent Claim 144 words

A deep UV photolithography station comprising a deep UV lithographic process tool; a recirculating air system for recirculating and filtering an airstream from adjacent said lithographic processing station, said recirculating air system comprising an air filtering system comprising an upstream air filtering bed positioned to receive the air stream recirculated by said recirculating air system and comprising activated carbon particles in the size range of 20×140 mesh impregnated with sulfuric acid for effectively removing airborne proton acceptors from the air stream as the air stream passes through said upstream air filtering bed, and a downstream air filtering bed positioned to receive the air stream that has passed through said upstream air filtering bed and comprising activated carbon particles in the size range of 20×140 mesh impregnated with a base selected to remove volatile sulfuric acid or sulfuric acid components released into said air stream.

Claim 26

Dependent Claim 150 words

The deep UV photolithography station of claim 21 further comprising a make-up air system for drawing air from an atmosphere that may be subject to a molecular contaminant including airborne proton acceptors, said makeup air system comprising an air filtering system comprising an upstream air filtering bed positioned to receive the air stream recirculated by said recirculating air system and comprising an upstream reagent selected to effectively remove airborne proton acceptors from the air stream as the air stream passes through said upstream air filtering bed, said upstream reagent releasing a characteristic volatile component into the air stream in sufficient quantity to be detrimental to the clean environment, and a downstream air filtering bed positioned to receive the air stream that has passed through said upstream air filtering bed and comprising a downstream reagent selected to remove the characteristic volatile component released by said upstream reagent into said air stream.

Claim 27

Dependent Claim 25 words

The air filter of claim 21 wherein said upstream reagent is impregnated on activated carbon particles at a doping level of between 5% and 90%.

Claim 28

Dependent Claim 15 words

The air filter of claim 23 wherein said doping level is between 20% and 50%.

Claim 29

Dependent Claim 234 words

An air filtering system comprising at least two chemically active air filtering beds in sequence along an air stream associated with a clean environment, said system comprising a first chemically active air filtering bed, constructed and arranged to filter air for use inside a clean environment, comprising activated carbon particles in the size range of 20×140 mesh impregnated with a reagent of sulfuric acid in a quantity selected to reduce the concentration of a first contaminant in an air stream associated with a clean environment to a level that is below that which is detrimental to a process associated with the clean environment, said reagent of sulfuric acid having the characteristic of releasing a contaminant into the air stream that is different from said first contaminant, a downstream chemically active air filtering system, constructed and arranged to filter air for use in a clean environment, comprising activated carbon particles in the size range of 20×140 mesh impregnated with a reagent having the characteristic of reducing the concentration of the contaminant released by said sulfuric acid reagent to a level that is below that which is detrimental to the associated clean environment, wherein the chemically active air filtering beds in said system are selected and cooperatively arranged so that said air filtering system has removed from the air stream said first contaminant and any volatile contaminants detrimental to said clean environment released by said system.

Claim 30

Dependent Claim 234 words

An air filtering system comprising at least two chemically active air filtering beds in sequence along an air stream associated with a clean environment, said system comprising a first chemically active air filtering bed, constructed and arranged to filter air for use inside a clean environment, comprising activated carbon particles in the size range of 20×140 mesh impregnated with a reagent of sulfuric acid in a quantity selected to reduce the concentration of a first contaminant in an air stream associated with a clean environment to a level that is below that which is detrimental to a process associated with the clean environment, said reagent of sulfuric acid having the characteristic of releasing a contaminant into the air stream that is different from said first contaminant, a downstream chemically active air filtering system, constructed and arranged to filter air for use in a clean environment, comprising activated carbon particles in the size range of 20×140 mesh impregnated with a reagent having the characteristic of reducing the concentration of the contaminant released by said sulfuric acid reagent to a level that is below that which is detrimental to the associated clean environment, wherein the chemically active air filtering beds in said system are selected and cooperatively arranged so that said air filtering system has removed from the air stream said first contaminant and any volatile contaminants detrimental to said clean environment released by said system.

Claim 31

Dependent Claim 31 words

The filtering system of claim 25 wherein said upstream reagent of sulfuric acid releases into the air stream said characteristic volatile component at a concentration of about 600 ppt or greater.

Claim 32

Independent Claim 219 words

A method for filtering an air stream for use in a clean environment to reduce the concentration of a process-limiting molecular contaminant therein to a level below that which is detrimental to a process associated with the clean environment, said method comprising the steps of: providing an upstream air filtering bed within an air handling system of a clean environment to receive an air stream from the clean environment, said upstream air filtering bed comprising an upstream chemically active reagent in a quantity selected to reduce the concentration of a process-limiting molecular contaminant in the air stream to a level below that which is detrimental to a process associated with the clean environment as said air stream passes through the upstream air filtering bed, said upstream chemically active reagent releasing a characteristic volatile component into said air stream at a concentration level that is detrimental to the associated clean environment process, and providing a downstream air filtering bed within the air handling system of the clean environment to receive the air stream that has passed through said upstream air filtering bed, said downstream air filtering bed comprising a downstream reagent selected to reduce the concentration of the characteristic volatile component released by said upstream reagent to a level below that which is detrimental to the associated clean environment process.

Claim 33

Independent Claim 219 words

A method for filtering an air stream for use in a clean environment to reduce the concentration of a process-limiting molecular contaminant therein to a level below that which is detrimental to a process associated with the clean environment, said method comprising the steps of: providing an upstream air filtering bed within an air handling system of a clean environment to receive an air stream from the clean environment, said upstream air filtering bed comprising an upstream chemically active reagent in a quantity selected to reduce the concentration of a process-limiting molecular contaminant in the air stream to a level below that which is detrimental to a process associated with the clean environment as said air stream passes through the upstream air filtering bed, said upstream chemically active reagent releasing a characteristic volatile component into said air stream at a concentration level that is detrimental to the associated clean environment process, and providing a downstream air filtering bed within the air handling system of the clean environment to receive the air stream that has passed through said upstream air filtering bed, said downstream air filtering bed comprising a downstream reagent selected to reduce the concentration of the characteristic volatile component released by said upstream reagent to a level below that which is detrimental to the associated clean environment process.

Claim 34

Dependent Claim 29 words

The method of claim 27 wherein the upstream air filtering bed that is provided comprises activated carbon particles in the size range of 20×140 mesh impregnated with sulfuric acid.

Claim 35

Dependent Claim 29 words

The method of claim 28 wherein the downstream air filtering bed that is provided comprises activated carbon particles in the size range of 20×140 mesh impregnated with a base.

Claim 36

Dependent Claim 21 words

The method of claim 29 wherein the activated carbon particles of the downstream air filtering bed are impregnated with potassium hydroxide.

Claim 37

Dependent Claim 21 words

The method of claim 29 wherein the activated carbon particles of the downstream air filtering bed are impregnated with potassium iodide.

Claim 38

Dependent Claim 33 words

The method of claim 27 wherein said upstream air filtering bed that is provided releases into the air stream said characteristic volatile component at a concentration level of about 600 ppt or greater.

Claim 39

Dependent Claim 23 words

The method of claim 27 wherein said upstream reagent that is provided has a higher vapor pressure than water under normal operating conditions.

Claim 40

Dependent Claim 30 words

The method of claim 27 wherein said upstream reagent that is provided off-gases at a level that is detrimental to processes conducted within the clean environment under normal operating conditions.

Claim 41

Dependent Claim 35 words

The method of claim 27 wherein the upstream reagent that is provided is selected to reduce the concentration of amines from the air stream as the air stream passes through said upstream air filtering bed.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-03-03	2000-09-02	2001-03-04	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-03-03	2004-09-02	2005-03-04	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-03-03	2008-09-02	2009-03-04	$7700.00	Window Closed / Lapsed

Air filtering within clean environments

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