1. A high efficiency filter comprising at least one nonwoven web layer, wherein said nonwoven web layer comprises a plurality of first fibers, a plurality of second fibers, and a binder, wherein said first fibers comprise a water non-dispersible polymer, wherein said first fibers have a length of less than 25 millimeters and a minimum transverse dimension of less than 5 microns, wherein said first and second fibers have a different configuration andor composition, wherein said first fibers make up at least 15 weight percent of said nonwoven web layer, wherein said second fibers make up at least 10 weight percent of said nonwoven web layer, wherein said binder makes up at least 1 weight percent andor not more than 40 weight percent of said nonwoven web layer, wherein said nonwoven web has a filtration efficiency of at least 85% (DIN EN 1822).
2. The high efficiency filter of claim 1, wherein said nonwoven web has a filtration efficiency (DIN EN 1822) of at least 95%, at least 99.5%, at least 99.95%, at least 99.995%, at least 99.9995%, at least 99.99995%, or at least 99.999995%.
3. The high efficiency filter of claim 1, wherein said nonwoven web has a pressure drop (DIN EN 1822) of less than 2, 1, 0.75, 0.5, 0.25 inches of water at maximum flow rate.
4. The high efficiency filter of claim 1, wherein said nonwoven web has a Mullen burst strength (TAPPI 403) of at least 1, 2, 4, 6, 10, 20, 40, or 60 pounds per square inch.
5. The high efficiency filter of claim 1, wherein said nonwoven web has a tensile strength (TAPPI T494) of at least 0.5, 1, 2, 3, 4, or 5 kg15 mm.
6. The high efficiency filter of claim 1, wherein said nonwoven web has a mean flow pore size (ASTM E 1294-89) of at least 0.2, 0.5, 1, 2, or 3 micron andor not more than 10, 5, 4, 3, 2, or 1 microns.
7. The high efficiency filter of claim 1, wherein said first fibers make up at least 10, 20, 30, 40, or 50 weight percent andor not more than 90, 75, 60 weight percent of said nonwoven web layer.
8. The high efficiency filter of claim 1, wherein said second fibers make up at least 10, 25, or 40 weight percent andor not more than 80, 70, 60, or 50 weight percent of said nonwoven web layer.
9. The high efficiency filter of claim 1, wherein said binder makes up at least 1, 2, or 4 weight percent andor not more than 40, 30, or 20 weight percent of said nonwoven web layer.10. The high efficiency filter of claim 1, wherein said first fibers have a length of less than 25, 10, 5, or 2 millimeters or a length of less than 10, 5 or 2 millimeters.
10. The high efficiency filter of claim 1, wherein said first fibers have a minimum transverse dimension of less than 5, 4, 3 microns.
11. The high efficiency filter of claim 1, wherein said first fibers are derived from a multicomponent fiber.
12. The high efficiency filter of claim 1, wherein said first fibers are formed by removing a water dispersible polymer from a multicomponent fiber comprising a plurality of said first fibers.
13. The high efficiency filter of claim 12, wherein said first fibers are formed by cutting said multicomponent fiber to the length of said first fibers prior to removing said water dispersible polymer.
14. The high efficiency filter of claim 12, wherein said water dispersible polymer is a sulfopolyester. The high efficiency filter of claim 1, wherein said first fibers comprise at least one polymer selected from the group consisting of polyesters, polyamides, polyolefins, polylactide, cellulose esters, polycaprolactone, polyactides, polyurethane, polyvinyl chloride, and combinations thereof.
15. The high efficiency filter of claim 1, wherein said second fibers are selected from the group consisting of cellulosic fiber pulp, inorganic fibers, polyester fibers, nylon fibers, polyolefin fibers, rayon fibers, lyocell fibers, cellulose ester fibers, and combinations thereof.
16. The high efficiency filter of claim 1, wherein said second fibers are inorganic fibers selected from the group consisting of glass fibers, carbon fibers, boron fibers, ceramic fibers, and combinations thereof.
17. The high efficiency filter of claim 1, wherein said binder is selected from the group consisting of synthetic resin binders, phenolic binders, and combinations thereof.
18. The high efficiency filter of claim 1, wherein said binder comprises a synthetic resin selected from the group consisting of sulfopolyesters, acrylic copolymers, styrenic copolymers, vinyl copolymers, polyurethanes, and combinations thereof.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method of fabricating a semiconductor device comprising forming a silicon nitride (SiN) film provided on a crystal surface of a nitride semiconductor by parallel plate PECVD (Plasma Enhanced Chemical Vapor Deposition), the SiN film having a hydrogen content smaller than 15 atomic percent,
wherein the parallel plate PECVD is performed under conditions that a ratio of a supply gas of SiH4: (SiH4+N2+ noble gas) is equal to or smaller than 1:200, an RF power density is 0.02 to 0.1 Wcm2, and a substrate temperature is 250 to 400\xb0 C.
2. The method as claimed in claim 1, wherein a film forming rate of the SiN film is equal to or smaller than 20 nanometersecond.
3. A method of fabricating a semiconductor device comprising forming a silicon nitride (SiN) film provided on a crystal surface of a nitride semiconductor by any one of ECRCVD (Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition), and ICPCVD (Inductively Coupled Plasma Chemical Vapor Deposition), the SiN film having a hydrogen content equal to or smaller than 5 atomic percent,
wherein the ECRCVD or the ICPCVD is performed with a ratio of a supply gas of SiH4:N2 equal to or smaller than 1:10, and
wherein the SiN film is formed under conditions that the substrate temperature is at least 250\xb0 C., and a film forming rate of the SiN film is equal to or smaller than 20 nanometersecond.