NOVELTY - The method involves patterning an inorganic membrane to selectively expose a portion of a membrane or membrane as a whole. A set of tracks of material damage is formed in the exposed portion of the inorganic membrane by irradiation with energetic ions. The track damaged material is chemically etched to define pores through the inorganic membrane with a predetermined geometrically defined cross sectional shape by selection of etching agents e.g. phosphoric acid, and etching conditions and with a controlled diameter range from less than 1 nm and up to micrometer scale.    USE - Method for fabricating isolated pores e.g. conical pores, cylindrical pores and biconical pores, in an inorganic membrane e.g. ultra thin inorganic film such as ultra thin silicon nitride film (all claimed), that is utilized for separation/filtration and biosensing process, fuel cells membrane, molecular sieve and mimicking biological channels, and as a support and windows for transmission electron microscopy, and masks for nanofabrication processes. Can also be used for fabricating hour-glass shaped pores in a silica film and an alumina film.    ADVANTAGE - The inorganic membrane is less than 10 nm thin, so as to enhance transport rate compared to micrometers thick polymer membranes. The material of membrane can withstand harsh conditions such as high temperatures, so that the applications for nanoporous membranes are widened. The method enables utilizing common lithographic techniques for easy integration of the membranes to micro/nanofluidic complex devices. The surface of the inorganic membrane and pore walls can be easily functionalized with desirable biological/chemical molecules such as DNA and proteins, using silane. The membrane contains small crystalline structures which can provide diffraction patterns. The membrane can serve as windows or collimators for low energy ion beams.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for an ultra thin inorganic film comprising isolated nanopores.    DESCRIPTION OF DRAWING(S) - The drawing shows a plan view of a silicon wafer in which a set of patterned membranes are fabricated using track etching.    Silicon wafer (12)