Filtration membranes, systems, and methods for producing purified water

Abstract

The description includes filtration membranes, related systems, and related methods for producing pure (e.g., ultrapure) water, including membranes, systems, and methods for preparing pure water that can be used in the manufacture of electronic and semiconductor devices.

Description

Filtration membrane, system and method for producing pure water The present invention relates to filtration membranes, related filtration assemblies and filtration systems, and related methods for producing pure (e.g., ultrapure) water, including membranes, systems and methods for preparing pure water that can be used to process (e.g., rinse) semiconductor and microelectronic substrates, components and devices. High-purity water, including water sometimes referred to as "ultrapure" water ("UPW"), is important for a variety of commercial uses, including in semiconductor processing (e.g., the manufacture of semiconductor devices, liquid crystal displays, silicon wafers, printed circuit boards, and other electronic and microelectronic devices), in nuclear power plant operations, and in pharmaceutical manufacturing. Purified water used in semiconductor processing is used, for example, as rinse water in semiconductor and microelectronics processing to clean or prepare the surface of a semiconductor or microelectronic device substrate, for example, as part of a "front-end" or "back-end" process recipe. Ultrapure water can be used in wet etching and cleaning ("WEC"), photolithography, and chemical mechanical polishing ("CMP") of in-process microelectronic devices. Water must be of very high purity because impurities in the water used to process a microelectronic device or semiconductor substrate and remaining on a substrate surface can affect the yield and short- and long-term performance of a final semiconductor or microelectronic device fabricated from the substrate. Filtration systems used to prepare ultrapure water must effectively remove impurities (also known as "contaminants") to a very high purity, and for manufacturing efficiency, the need to replace a filter element must be minimized over an extended period of time. Removing and replacing a filter element in a filtration system that supplies ultrapure water to semiconductor processing equipment may require shutting down the equipment for the period of time required to remove and replace the filter element, known as a "replacement" cycle. Replacement cycles are expensive in terms of lost time during the use of semiconductor processing equipment, which results in reduced processing efficiency and increased overall costs. The frequency and cycle of replacements can affect the efficiency of equipment that directly uses the purified water, and can also affect processes performed downstream of the directly affected equipment. Ultrapure water used in semiconductor processing is not completely pure, but is understood to contain very low levels of contaminants, including silicon dioxide particles (colloidal and hard SiO 2 particles), organic matter (dissolved and undissolved), and dissolved metals or metal-containing compounds (such as boron, silicon (such as SiO 2), iron, and titanium). Boron and silica impurities are particularly problematic because current filtration systems are not effective at removing and retaining boron and silica (e.g., colloids and solid silica particles) or do not operate long enough to effectively remove these impurities from a water stream. A common design for ultrapure water production facilities includes an ion exchange (IEX) resin in the form of a bed of polymer beads through which water passes to remove ions from the water. The polymer resin beads attract and retain trace ionic impurities, removing impurities from the water flowing through the polymer bead bed. With these ion exchange systems, after the system has been used to remove boron, silicon (e.g., solid and colloidal silica particles, or dissolved silica), or both, from a water source for a certain period of time, the ability of an ion exchange resin bed to remove and contain (retain) the boron, silicon, or both becomes exhausted. The ion exchange system's ability to continue removing additional amounts of boron or silicon (silicon dioxide) from the water is exhausted, and it no longer removes boron or silicon from a water stream. When this occurs, these impurities begin to pass through the ion exchange system and "leak" from the system into downstream equipment as unwanted impurities. As the complexity of microelectronic device integration continues to increase, the content of trace contaminants in ultrapure water is increasing. Therefore, ultrapure water with higher purity is required to meet goals (economic or otherwise) related to semiconductor or microelectronic device chip yield and overall reliability. The following description relates to porous polymer filtration membranes comprising a porous polymer base membrane and an aminopolyol ligand containing at least three hydroxyl groups attached to the base membrane ("aminopolyol" or "aminopolyol ligand"). The description also relates to filtration assemblies and filtration systems comprising such filtration membranes, and methods of using such filtration membranes, filtration assemblies, and filtration systems to filter a water source ("source water") to form purified (e.g., ultrapure) water. The described filtration membrane is used to remove impurities from a water source, and is particularly used to remove metallic impurities (such as dissolved boron and silicon (e.g., SiO 2) to form pure (e.g., ultrapure) water. Purified water prepared according to the described method and containing very low amounts of boron and silicon can be used in industrial processes, including but not limited to semiconductor and microelectronics manufacturing processes, such as for rinsing the surfaces of semiconductor and microelectronic substrates. As used herein, the term "ultrapure water" is given its meaning commonly used in the semiconductor processing industry to refer to water that has been treated to a very high purity level with respect to a group of contaminant types, including: organic and inorganic compounds; dissolved and particulate matter; volatile and non-volatile impurities; charged (anionic, cationic) and non-ionic impurities; reactive and inert impurities; hydrophilic and hydrophobic impurities; and dissolved gases. Ultrapure water is water that has been treated to remove organic particulates and dissolved gases, as well as other dissolved trace impurities. Ultrapure water is typically processed through three stages, including: a pretreatment stage to produce pure water; a preliminary stage to further purify the water; and a final "polishing" stage. Various published standards exist for determining impurity levels in ultrapure water. For microelectronics applications, these groups include Semiconductor Equipment and Materials International (SEMI) (microelectronics and photovoltaics), ASTM International (semiconductors, power), the Electric Power Research Institute, the American Society of Mechanical Engineers (ASME) (power), and the International Association for the Properties of Water and Steam (IAPWS) (power). Pharmaceutical manufacturers adhere to water quality standards established by pharmacopoeias, three examples of which are the United States Pharmacopoeia, the European Pharmacopoeia, and the Japanese Pharmacopoeia. ASTM D5127 "Standard Guide for Ultrapure Water for the Electronics and Semiconductor Industries" and SEMI F63 "Guide for Ultrapure Water Used in Semiconductor Processing" document common requirements for ultrapure water quality. In one aspect, the present invention relates to a polymer filtration membrane comprising: a porous polymer base membrane and an amino polyol ligand having three or more hydroxyl groups attached to the polymer base membrane. In another aspect, the present invention relates to a system for removing an impurity from a source water stream. The system includes a polymeric filtration membrane comprising a porous polymeric base membrane and aminopolyol ligands having three or more hydroxyl groups attached to the polymeric base membrane. The system also includes an ion exchange resin and a source water stream passing through the polymeric filtration membrane and the ion exchange resin. In another aspect, the present invention relates to a method for removing an impurity from a source water stream, the method comprising flowing the source water through a polymer filtration membrane comprising a porous polymer base membrane and an aminopolyol ligand having three or more hydroxyl groups attached to the polymer base membrane. The following description relates to filtration membranes comprising a porous polymer-based membrane and an aminopolyol ligand containing at least three hydroxyl groups ("aminopolyol" or "aminopolyol ligand") as part of the filtration membrane. The description also relates to filtration assemblies and filtration systems comprising such filtration membranes, and methods of using such filtration membranes, filtration assemblies, and filtration systems to filter a water source to form purified (e.g., ultrapure) water. The described filtration membranes can be used to remove impurities from a water source, and are particularly useful for removing metallic impurities such as boron and silicon (e.g., dissolved SiO 2. Or colloidal or solid SiO 2 particles) to form pure (e.g., ultrapure) water. 2) can be used in industrial processes, including (but not limited to) semiconductor and microelectronics manufacturing processes, such as for rinsing the surfaces of semiconductor and microelectronic substrates. The described filter membrane can be configured for use in a microelectronic or semiconductor device manufacturing system as a point-of-use filtration system that directly treats a water source upstream of the manufacturing system to supply purified (e.g., ultrapure) water for use with the manufacturing system. Alternatively, the described filter membrane, filter assembly, or filter system can be used to produce purified water (e.g., ultrapure water) for storage in a storage container for optional storage, transportation, and final use. The membrane described comprises a porous polymer base membrane to which an aminopolyol ligand is directly or indirectly attached. The base membrane (sometimes simply referred to as a "substrate") can be a membrane in the form of a polymer sheet (i.e., a flat, planar, double-sided porous membrane) made of any useful polymer material or combination of materials. Example base membranes can be made of polymer materials known for use in porous filtration membranes and capable of chemically modifying the aminopolyol ligand to attach to one of its surfaces. The base membrane can be made of a polymer containing a reactive site to which the aminopolyol ligand can attach, or can be made of a polymer that can be chemically coated or modified in other ways to provide a reactive site to which the aminopolyol ligand can attach. Example base films can be formed from one or more polymeric materials, for example, a single polymeric material, a mixture of different polymeric materials, or a polymeric material and a non-polymeric material. The polymer materials that can be used to form the base membrane include various polymers, including hydrophobic polymers such as polyolefins or halogenated polymers. Exemplary polyolefins include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polybutylene (PB), polyisobutylene (PM), and copolymers of two or more of ethylene, propylene, and butylene. In certain embodiments, a base membrane may include ultra-high molecular weight polyethylene (UPE). Ultra-high molecular weight polyethylene filter materials (such as UPE membranes) are typically composed of polyethylene with a molecular weight greater than about 1×10 6 Dalton (Da) (such as about 1×10 6 to 9×10 6 Da or 1.5×10 6 to 9×10 6 Crosslinking between polyolefin polymers (such as polyethylene) can be promoted by using heat or crosslinking chemicals such as peroxides (e.g., dicumyl peroxide or di-tert-butyl peroxide), silanes (e.g., trimethoxyvinylsilane), or azo ester compounds (e.g., 2,2'-azo-bis(2-acetoxy-propane)). Exemplary halogenated polymers include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), fluorinated ethylene polymer (FEP), polyhexafluoropropylene, and polyvinylidene fluoride (PVDF). In other embodiments, a base film may be made of a polymer selected from polyamide, polyimide, polysulfone, polyethersulfone, polyarylsulfone, polyamide, polyacrylate, polyester, nylon, cellulose, polycarbonate, or a combination thereof. A base film comprising any one or a combination of these polymers can include, consist of, or consist essentially of any one or a combination of these polymers. A base film consisting essentially of a polymer or combination of polymers is a base film containing the polymer or combination of polymers and no more than minor amounts of other materials (e.g., no more than 5, 2, 1, 0.5, or 0.1 weight percent of other materials). Specific examples of polymers used to prepare porous polymer filtration membranes are described in U.S. Patent Publication No. 2020 / 0254398, which is incorporated herein by reference in its entirety. In certain modes of practice, the polymer material of the base membrane may be chemically modified to facilitate modification of the base membrane with an aminopolyol ligand. The aminopolyol ligand may contain an amine group, which may facilitate adhesion to a polymer material of the base membrane. If the polymer material itself is not amine-reactive, it may be modified, such as by halogenation or haloalkylation, to provide a surface reactive chemistry for attachment of the aminopolyol ligand. In certain modes of practice, the polymer material of a base film is halogenated to provide amine reactive sites. For example, polyethylene can be chlorinated by reacting gaseous chlorine at a temperature greater than 50°C, optionally diluted with an inert gas, or solid polyethylene powder (see, for example, U.S. Pat. No. 2,928,819). In another mode of practice, the polymer of a base membrane can be haloalkylated, such as chloromethylated. Chloromethylation is a known technique for modifying polymers and typically uses a chloromethylating agent (e.g., bischloromethyl ether (BCME); chloromethyl methyl ether (CMME); formaldehyde / methanol / hydrogen chloride / chlorosulfonic acid). Lewis acids and Friedel-Crafts reaction catalysts (such as zinc chloride, zinc oxide, or ferric chloride) can be used with the chloromethylating agent at elevated temperatures to modify the polymer (e.g., see US 2003 / 0018091 (Pafford et al.) and WO 2008 / 144115 (Harris et al.)). To provide the ligands of the present invention on the polymeric material, the haloalkyl group of the haloalkyl-modified filter material can be reacted with an amine polyol or an amine polyphosphonic acid, resulting in covalent bonding of the ligand to the filter material surface. In another mode of practice, the amino polyol ligand can be attached to a filter material by attaching it with a reactive cross-linking coating. For example, the polymer material can be coated with an amine-reactive polymer (such as poly(vinylbenzyl chloride), polyepichlorohydrin, or epoxy resin). The coated polymer material can then be cross-linked, and the remaining reactive sites can be used for attachment of the desired ligand. For example, poly(vinylbenzyl chloride) can be dissolved in a suitable solvent, dried onto a porous polymer base membrane, cross-linked with a diamine, polyamine, or any other multifunctional reactive cross-linking agent, and then the amine-containing polyol ligand can be attached. Using a similar method, cross-linking and ligand attachment can occur simultaneously. Alternatively, the amine-reactive polymer can be cross-linked via irradiation or by cross-linking using a photoinitiator, followed by attachment of the amine-containing ligand. In another practical mode, ligand attachment can occur prior to coating the polymeric substrate. For example, an aminopolyol-functionalized polymer can be prepared by reacting an aminopolyol ligand with a polymeric material (such as poly(vinylbenzyl chloride)) that has a functional group reactive with the amine of the ligand. The substrate can then be coated with the resulting aminopolyol ligand-modified polymer and dried. Optional cross-linking techniques may also be used. In another mode of practice, the base film can be modified with the desired aminopolyol ligand via monomer crosslinking. For example, the desired aminopolyol ligand can be in the form of a reactive monomer containing an acrylamide, vinyl, or other suitable unsaturated group. An example of a reactive monomer containing an aminopolyol is the reaction product of vinylbenzyl chloride and N-methylglucosamine. The aminopolyol-containing monomer can be added to a monomer formulation containing a difunctional monomer, such as N,N'-methylenebisacrylamide. These monomer formulations can also contain a photoinitiator, such as OMNIRAD 2959 (1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one). Once the membrane is imbibed with the resulting monomer solution, it can be irradiated (UV, electron beam, gamma, etc.) to form a crosslinked coating in which the desired aminopolyol ligand is incorporated (see, for example, WO2017 / 205722 (Jaber et al.)). In another mode of practice, the desired aminopolyol ligand can be attached to a polymeric material via grafting from a membrane. "Grafting" can be accomplished by irradiating the polymeric material in the presence of a photoinitiator and an unsaturated monomer containing the desired aminopolyol ligand (see, for example, WO2016 / 081729 A1 (Jaber et al.)). In another mode of practice, the polymeric material can be attached to the desired aminopolyol ligand by grafting from the membrane using electron beam or gamma irradiation. Grafting using electron beam or gamma irradiation can be accomplished using techniques known as pre-irradiation grafting or simultaneous irradiation grafting. In another practical mode, a polymer material can be embedded with resin particles to form a hybrid particle / membrane base membrane. For example, porous poly(styrene-co-divinylbenzene) resin particles with the desired amino polyol ligand attached can be introduced into a polymer mixture for film extrusion or film casting. In this way, the resulting porous polymer membrane will be embedded with the porous particles with the desired amino polyol ligand attached. In some embodiments, the resulting membrane can have a compact particle retention membrane placed downstream of the membrane containing the porous particles (see, for example, U.S. 2009 / 0039019 A1 (Raman)). The amount (concentration) of the aminopolyol ligand introduced into the polymeric material of the base membrane can be sufficient to allow the aminopolyol ligand to be fixed to a surface of the base membrane at a desired density. A ligand solution can be applied to the surface of a base membrane by any useful technique, such as by spraying, immersion, soaking the base membrane in the solution, etc. Ideally, the entire surface of the base membrane can be contacted with the solution, such as all inner surfaces of a porous filter membrane. If desired, the application step can include manipulating the filter material, for example, by rolling or squeezing a porous filter medium to wet all surfaces of the porous filter. Porous base membranes and filter membranes made from base membranes by chemically attaching an amino polyol ligand to the base membrane can be described based on various physical characteristics of a porous filter membrane. As used herein, an exemplary porous base membrane of a porous filter membrane comprises a porous solid in the form of a double-sided sheet having opposing surfaces (sides), a length and a width extending along the two surfaces, and a thickness extending between the two opposing surfaces. The porous membrane contains porous (e.g., microporous) interconnected pathways (pores, channels, gaps) extending from one surface of the membrane to the opposing surface of the membrane. The pathways typically provide a tortuous channel or path through which the source water to be filtered must pass. Metal species small enough to pass through the pores of the membrane can be captured on the membrane through interaction with the amino polyol ligand (such as through a chelating interaction between the ligand and the metal). This is referred to as a "non-sieving filtration mechanism." Porous membranes can also be used to physically prevent particles (e.g., metal-containing particles) present in source water from passing through the membrane. Particles larger than the pores will be prevented from entering the membrane, or may be physically prevented from passing through the membrane by the structure of the membrane (i.e., where the particles are removed by a sieving-type filtration mechanism). Source water passes through the membrane, resulting in water that contains a reduced amount of contaminants removed by the non-sieving or sieving mechanism, such as a reduced amount of ionic metal species, a reduced amount of metal-containing particles, or both. Thus, a porous filtration membrane described comprising a polymer-based membrane having aminopolyol ligands attached thereto can effectively remove metal and metal ion contaminants from source water passing through the membrane, as well as remove materials that are too large in physical size to pass through the pores of the membrane. The porous membranes of the present invention may be described with reference to one or more properties of the membrane. The example porous polymer filtration membranes described herein can be characterized by physical characteristics including pore size, bubble point, and porosity. For example, the membranes can be described based on their bubble point, which is often used to reflect pore size. The bubble point of a membrane is an indirect measurement of pore size, which is based on the concept that for a specific fluid and pore size, the pressure required to force a bubble through a porous membrane, while the membrane is continuously wetted, is inversely proportional to the pore size of the membrane. Methods for determining the bubble point may include wetting a membrane, contacting one side of the membrane with a gaseous fluid, and then determining the pressure at which the gaseous fluid can pass through the membrane as bubbles emitted from the opposite surface of the membrane. To determine the bubble point of a porous material, a sample of the porous material is immersed in ethoxy-nonafluorobutane HFE 7200 (available from 3M) at a temperature of 20 to 25°C (e.g., 22°C) and wetted with it. An air pressure is applied to one side of the sample with compressed air and gradually increased. The differential pressure at which the wet flow rate is equal to half the dry flow rate (the flow rate without the wetting solvent) is called the bubble point. In the example filter membranes described herein, a porous filter membrane (e.g., a base membrane, or a base membrane with attached amino polyol ligands) can have any useful bubble point, wherein examples of useful bubble points are in the range of about 2 psi to about 400 psi, about 4 psi to about 200, or preferably about 4 psi to about 160 psi when using ethoxy-nonafluorobutane (HFE-7200) as the wetting solvent and at a temperature of 22 degrees Celsius. Another characteristic of a porous membrane is the pore size of the membrane, such as the average pore size. Pore size can be measured by known techniques, such as mercury porosimetry (MP), scanning electron microscopy (SEM), liquid displacement (LLDP), or atomic force microscopy (AFM). A porous membrane as described (e.g., a base membrane, or a base membrane with attached amino polyol ligands) can have any pore size that will allow the filter membrane to effectively function as a filter membrane. The pore size can be correlated with bubble point determination. In some embodiments, the porous filter membrane can have an average pore size in a range of about 0.001 microns to about 5 or 10 microns (e.g., 0.01 to 0.8 microns). The average pore size can be selected based on one or more factors, including fluid flow rate, pressure, pressure drop considerations, viscosity considerations, impurities in the liquid to be treated (such as the amount of metallic impurities), and any particle size of the impurities. Furthermore, the present invention contemplates the use of polymer-based membranes or porous filtration membranes having generally uniform pore size due to a high degree of pore symmetry throughout the thickness of the membrane, as well as membranes having non-uniform pore size (variable pore size) due to pore asymmetry. The pores can be isotropic or anisotropic, skinned or unskinned, symmetric or asymmetric, and any combination thereof. A porous polymer filter layer as described can have any porosity that will allow the porous polymer filter layer to be effective as described herein. Example porous polymer filter layers can have a relatively high porosity, such as a porosity of at least 60%, 70%, or 80%. As used herein, and in the art of porous bodies, the "porosity" (sometimes also referred to as void fraction) of a porous body is a measure of the void (i.e., "empty") space in the body as a percentage of the total volume of the body, and is calculated as the fraction of the void volume of the body over the total volume of the body. A body with a void fraction of zero is completely solid. The porous membrane described herein can be a sheet having any useful or desired geometric configuration suitable for use in a filter assembly described herein. Example porous membranes can have a shape selected from circular, semicircular, elliptical, semi-elliptical, or polygonal (e.g., square, rectangular, hexagonal, or octagonal). The porous membrane can be in the form of a flat sheet, a corrugated sheet, a pleated sheet, and a hollow fiber. A porous membrane described can be in the form of a sheet of any useful thickness, for example, a thickness in a range of 20 to 400 microns, such as 40 or 80 to 100 or 200 microns. As described herein, a porous filtration membrane comprises a base membrane made of a polymer material, to the surface of which is chemically attached an aminopolyol ligand containing at least three hydroxyl groups ("aminopolyol" or "aminopolyol ligand"), such as n-methylglucosamine. In a method for producing purified (ultrapure) water by filtering source water through a filter medium, the aminopolyol ligand (such as n-methylglucosamine) has been identified as effective when placed on the surface of a filter medium for removing metal ions from source water (e.g., by a non-sieving filtration mechanism). The amino polyol ligand can be n-methylglucosamine or another amino polyol ligand that effectively removes metal ions from source water by filtration (e.g., by a non-sieving filtration mechanism). Specific examples of amino polyol ligands other than n-methylglucosamine are described in U.S. Patent Publication No. 2020 / 0254398, which is incorporated herein by reference in its entirety. As described in Publication No. 2020 / 0254398, an "aminopolyol ligand" is a chemical moiety comprising nitrogen and a polyol moiety containing three or more hydroxyl groups. Examples of aminopolyols having three hydroxyl groups include 3-aminobutane-1,2,4-triol (threonine), 4-aminobutane-1,2,3-triol, methylaminoglycerol (1-(methylamino)propane-1,2,3-triol), 2-(methylamino)propane-5-aminopentane-1,2,4-triol, and 5-aminopentane-1,2,3-triol. Examples of amino polyols having four hydroxyl groups include 1-aminopentane-1,2,3,5-tetrol, 1-aminopentane-1,1,2,2-tetrol, 1-amino-2,2-di(hydroxymethyl)propane-1,3-diol, 1-aminohexane-2,3,4,5-tetrol, 1-(methylamino)hexane-2,3,4,5-tetrol, 2-aminopentane-1,2,4,5-tetrol, 2-aminopentane-1,2,3,4- Tetrol, 3-aminopentane-1,2,4,5-tetrol, 4-aminopentane-1,1,2,3-tetrol, 4-aminopentane-1,2,3,5-tetrol, 5-aminopentane-1,2,3,4-tetrol (libamine); 1-amino-1-deoxyribonucleic acid alcohol, 5-aminopentane-1,1,1,5-tetrol, 6-aminohexane-1,2,3,4-tetrol and 6-(methylamino)hexane-1,2,4,5-tetrol. Examples of amino polyols having five hydroxyl groups include 1-aminopentane-1,2,3,4,5-pentanol, 1-(methylamino)hexane-1,2,3,4,6-pentanol, 5-(methylamino)hexane-1,2,3,4,6-pentanol, 6-aminohexane-1,2,3,4,5-pentanol, 5-(methylamino)hexane-1,2,3,4,6-pentanol, 6-(methylamino)hexane-1,2,3,4,5-pentanol (n-methylglucamine), 1-deoxy-1-(methylamino)-D-glucitol, and 6-(butylamino)hexane-1,2,3,4,5-pentanol. Examples of amino polyols having six hydroxyl groups include 6-(3-hydroxypropylamino)hexane-1,2,3,4,5-pentanol, 6-(2-hydroxyethylamino)hexane-1,2,3,4,5-pentanol, 6-(2-hydroxyethylamino)hexane-1,2,3,4,5-pentanol, 1-(propylamino)hexane-1,2,3,4,5,6-hexanol, 6-(methylamino)hexane-1,1,2,3,4,5-hexanol, 7-(methylamino)heptane-1,2,3,4,5,6-hexanol, and 7-(propylamino)heptane-1,2,3,4,5,6-hexanol. Examples of amino polyols having seven hydroxyl groups include 6-(2,3-dihydroxypropylamino)hexane-1,2,3,4,5-pentanol, 1-(ethylamino)hexane-1,1,2,3,4,5,6-heptanol, 1-(2-hydroxyethylamino)hexane-1,2,3,4,5,6-hexanol, and 8-(methylamino)octane-1,2,3,4,5,6,7-heptanol. Examples of amino polyols having more than seven hydroxyl groups include 6-(2,2,2-trihydroxyethylamino)hexane-1,2,3,4,5-pentanol, 1-(2,3-dihydroxypropylamino)hexane-1,2,3,4,5,6-hexanol, and 6-(2,3,4,5,6-pentahydroxyhexylamino)hexane-1,2,3,4,5-pentanol. The present invention also contemplates all enantiomers and stereoisomers of the amino polyols, such as described herein. Example filtration membranes (including a polymeric base membrane chemically modified to include an aminopolyol ligand) can have the aminopolyol ligand attached to a surface of the base membrane in a useful manner. An example includes a porous polymeric base membrane made of a polyolefin (e.g., polyethylene) that has been chemically modified by attaching the aminopolyol ligand directly to the base membrane polymer (i.e., to the polyolefin). The filtration membrane can have a surface that contacts liquid source water during a filtration process, and such surface presents the attached aminopolyol ligand to the source water. In some cases, an aminopolyol ligand-modified surface of a filtration membrane can be represented by the formula: MF-NP, where MF is the filter material (e.g., polyolefin), N is nitrogen, and P represents the polyol portion of the aminopolyol ligand. In other cases, an aminopolyol ligand-modified surface can be represented by MF-LNP, where MF, N, and P have the definitions herein, and L is a chemical linking agent that links the aminopolyol to the filter material. Example aminopolyol ligands are chemically attached (i.e., covalently bonded) to the polymer of the base membrane. In other embodiments, an aminopolyol ligand-modified surface can be represented by Poly-NP, where N and P have the definitions herein, and Poly is a polymer backbone to which the polyol is attached. For this embodiment, the filter material is internally coated with a modified polymer coating, which may also be cross-linked. FIG. 1 shows an example of an aminopolyol ligand (n-methylglucamine, as shown) attached directly to a polymer (eg, polyolefin) of a base film 10 . A porous filter membrane can be present as part of a filtration assembly that includes a housing containing the filter membrane and passing a liquid through the membrane for a filtration step. The filter membrane can be included as part of a filter cartridge or other filtration product or assembly that acts as a housing. The housing containing the filter cartridge and filter membrane is fluid-tight except for inlet and outlet ports and is capable of allowing liquid to pass through the inlet port, through the membrane contained in the housing without bypassing the membrane, and then exit the housing through the outlet port. A housing can be included as a component of a larger filtration or water purification system, which can further include multiple filtration or purification devices connected in line with each other (in series). A larger filtration system would include a filtration membrane as described herein (e.g., as part of a filtration assembly or as part of a filter cartridge) positioned in a flow path of a liquid (source water) such that at least a portion of the liquid flows through the filtration membrane, causing the filtration membrane to remove a certain amount of impurities or contaminants from the liquid. Specifically, source water passing through a filtration membrane as described herein can effectively remove impurities selected from dissolved metals and metal ions (e.g., dissolved iron, titanium, and boron), dissolved silica, and silica particles (colloidal or solid). The structure of a filter assembly or filter cartridge can include one or more of a variety of additional materials and structures that support the filter membrane within the filter assembly or filter cartridge to allow fluid to flow from a filter inlet, through the filter material (e.g., filter membrane), and out through a filter outlet. The filter membrane supported by the filter assembly or filter cartridge can be of any useful shape, such as a pleated cylinder, a cylindrical pad, one or more non-pleated (flat) cylindrical sheets, a pleated sheet, etc. Referring to FIG2 , a schematic diagram of an example of a filtration apparatus and a method for removing metal contaminants from flowing liquid source water is shown, wherein the source water passes through a porous polymer filtration membrane containing an amino polyol ligand. As shown in FIG2 , filtration apparatus 100 comprises a porous polymer filtration membrane 102 comprising an amine polyol ligand attached to the surface of a porous polymer base membrane. Filtration apparatus 100 includes a housing 104, which provides an exterior structure for filtration apparatus 100 and fluidically seals an interior portion of the filter containing filtration membrane 102. Housing 104 can be of any shape and size, such as cylindrical, polygonal, or the like. Filtration apparatus 100 includes an inlet port 106 for receiving source water to be filtered. Inlet port 106 can be configured to connect to a fluid supply line that supplies a source water stream (not shown). Accordingly, inlet port 106 can include a valve, a gasket, etc. (not shown) to facilitate connection to a fluid supply. Source water can flow through inlet port 106 in the direction indicated by arrow 116 and into headspace 114 defined by an input-facing surface 124 of porous polymer filter membrane 102, the interior surface of housing 104, and inlet port 106. The interior portion of the filter apparatus 100 contains a filter membrane 102 in any suitable position or configuration, with FIG2 showing a filter membrane 102 having a disc-like shape (shown in cross-section). An edge 122 of the filter membrane 102 (e.g., the outer circumference of the membrane) can contact or otherwise form a fluid-tight seal with the inner surface of the housing 104. The filter membrane 102 also includes an input-facing surface 124 that first contacts the source water and an output-facing surface 126, through which the treated (filtered) source water with reduced levels of contaminants (metals, metal ions, etc.) flows. The filter device 100 optionally includes one or more structures that support the filter membrane 102 inside the filter device. Any arrangement for supporting the filter membrane 102 can be used, such as a frame, bracket, clip, mesh, net, cylinder or cage, or adhesive that can be used to support a membrane 102. As shown in Figure 2, the filter device 100 includes a frame having frame portions 110 and 112, wherein the frame portion 110 contacts the inner surface of the housing 104 attached to the portion 112. The portion 112 can contact the output-facing surface 124 of the membrane 102 and can provide support for the membrane 102 during filtration. The frame portion 112 can have a grid-like structure to freely allow the filtered liquid to enter the rear space 120 inside the filter device 100, while still providing structural support for the polymer porous filter membrane 102 under the fluid pressure caused by the flow of source water through the membrane 102. In use, a liquid such as source water enters the filter device 100 through the inlet 106 in the direction indicated by arrow 116 and then fills the head space 114 within the filter device 100. Sufficient fluid pressure is applied to move the source water through the porous polymer filter membrane (102) at a desired flow rate. After passing through the filter membrane 102, the source water enters the rear space 120 and then exits the housing 104 through the outlet 108. A filter membrane as described, or a composite ("stack") filter membrane comprising at least one filter membrane as described (see below), should allow a useful flow rate (volume per unit time) of a fluid (e.g., source water) through the filter membrane during use in a filtration process. A useful fluid flow rate is a rate that allows for efficient (preferably cost-effective) operation of a filtration system having a filter membrane for supplying a desired flow rate (volume per unit time) of purified water to equipment such as semiconductor processing equipment. Exemplary flow rates for the described porous membranes can be in the range of about 0.1 L / min to about 40 L / min, or more preferably about 10 L / min to about 30 L / min (liters per minute). Alternatively, the flow rate of a fluid through a porous membrane can be expressed as the amount of liquid flowing per unit time and pressure per filter area (e.g., liters / m2). 2 / h = LMH), such as about 100 LMH / bar to about 30,000 LMH / bar, or more preferably about 5,000 LMH / bar to about 15,000 LMH / bar. According to certain example filter membranes described, the filter membrane can be a composite membrane (i.e., a "stacked membrane") comprising two or more filter membranes that are effective in removing the same or different contaminants from source water flowing through the membranes. A composite membrane can comprise at least one filter membrane as described, made from a base polymer having amino polyol ligands attached. This membrane will effectively remove dissolved metal-containing contaminants (e.g., dissolved metals, metal ions, or metal compounds) (such as boron) and contaminants such as silicon dioxide from a source water stream passing through the filter membrane, for example, by a non-sieving filtration mechanism. A second membrane can be different from the first membrane and can effectively remove other (e.g., non-metallic or undissolved metals or metal ions) types of contaminants from the source water, for example, can effectively remove contaminants such as silicon dioxide (SiO 2) Solid particle pollutants. Porous polymer filtration membranes for removing solid particulate contaminants such as silica particles are known and can take the form of, for example, a polymer filtration membrane described herein that does not require an aminopolyol ligand. Typically, a useful filtration membrane can be microporous (e.g., having an average pore size in the range of 10 nm to 10 μm) and made from a useful polymer, such as, but not limited to, polysulfone, a polyolefin (e.g., polyethylene), or a fluoropolymer (e.g., a fluorinated polyolefin). Example membranes can have a bubble point (measured using HFE) in the range of approximately 10 to 100 psi (e.g., 40 to 60 psi) and can effectively remove silica particles using a combination of a sieving mechanism and a non-sieving mechanism. A composite membrane may also contain one or more additional layers, namely one or more support layers, to maintain the composite's structure. A support layer is a porous membrane or film that is supportedly attached to a composite membrane to provide support for the composite membrane while still allowing source water to flow from one side of the membrane to the other. For example, the support layer need not perform any filtration function and may have pores or openings that are substantially larger than the pores or openings of one of the composite's filter membranes, such that the flow resistance of source water through the support layer is less than the flow resistance of one of the composite membrane's filter membranes. The example support membrane may comprise a macroporous polymer film made from any useful polymer having a structure and thickness to provide the composite support. The pores may be openings or windows that are visible without magnification. The polymer may be any polymer having sufficient structure and chemical non-reactivity (inertness), such as a polyolefin or a modified polyolefin polymer (e.g., high-density polyolefin, polypropylene, perfluoroalkoxy, etc.). 3 shows a schematic diagram of a single example of a composite membrane of the present description. As schematically shown, composite membrane 150 includes upstream surface 152, downstream surface 162, upstream non-filtering support membrane 154, filtering membrane 156, an additional filtering membrane 158, and downstream non-filtering support membrane 160. Upstream non-filtering support membrane 154 is a non-filtering membrane body that provides physical and structural support for composite membrane 150. Upstream support membrane 154 is porous and allows source water to flow through the membrane with a relatively low resistance compared to the overall flow resistance of the composite. Filter membrane 156 is a filter membrane as described, comprising a porous polymer-based membrane as described with chemically attached amino polyol ligands. Filter membrane 158 is a membrane suitable for filtering contaminants including solid particles, such as silica particles. Downstream support membrane 160 is porous and allows source water to flow through the membrane with a relatively low resistance compared to the overall flow resistance of the composite. In use, source water enters upstream surface 152, passes through upstream non-filtering support membrane 154, and contacts and passes through filter membrane 156, which comprises one of the described porous polymer-based membranes with chemically attached amino polyol ligands. Passing the source water through filter membrane 156 allows membrane 156 to remove dissolved contaminants (such as dissolved metals) from the source water, for example, by a non-sieving filtration mechanism. The source water then passes through filter membrane 158, which can remove particulate contaminants (such as silica particles) from the source water by a sieving filtration mechanism. The source water then passes through downstream non-filtering support membrane 160. In another example shown in FIG4 , a filtration device 200 includes a first porous polymer membrane 202 and a second porous polymer membrane 222. The two polymer membranes 202, 222 may be included in a composite membrane, or may be separate membranes arranged in series with the output-facing surface of the first porous polymer membrane 202 directly contacting the input-facing surface of the second porous polymer membrane 222. At least one of the first and second porous polymer membranes 202, 222 has attached thereto an aminopolyol ligand as described. The filtration device 200 includes a housing 204, an inlet port 206, a headspace 214, a frame having frame portions 210 and 212 for supporting the membranes during filtration, a backspace 220, and an outlet port 208. According to a single example of a useful combination of membranes 202 and 222, filter membrane 222 can be a filter membrane as described, containing a porous polymer-based membrane and amino polyol ligands. This membrane will effectively remove a large amount of dissolved metals, metal ions, or metal-containing compounds (such as boron) from a source water stream passing through filter membrane 222, for example, by a non-sieving filtration mechanism. Membrane 202 can be a porous polymer membrane that can effectively remove other (non-dissolved metal or metal ion) contaminants from the source water, for example, it effectively removes solid particulate contaminants such as silicon dioxide (SiO 2) Granules. 4 , filtration apparatus 200 includes a frame having frame portions 210 and 212, wherein frame portion 210 contacts the inner surface of housing 204 attached to portion 212. Portion 212 can contact output-facing surface 224 of membrane 222 and can provide support for membranes 202 and 222 during filtration. In an example filtration system, a filtration membrane described or a filtration apparatus comprising a filtration membrane described can be used in a larger filtration system that further comprises one or more additional filtration or purification devices that remove impurities from a source water stream that is also filtered through the filtration membrane described (comprising a base membrane and attached amino polyol ligands). The one or more additional filtration or purification devices can include, for example, an ion exchange system that removes a large amount of trace impurities from the source water before or after the source water passes through the filtration membrane described (comprising a base membrane and attached amino polyol ligands), a UV irradiation device, a reverse osmosis device, etc. Ion exchange resins are known for a variety of specific applications for removing impurities from liquids. These typically include use in industrial water treatment, power generation, pharmaceutical applications, wastewater and recycling, and for the preparation of ultrapure water. Examples of ion exchange resins specifically indicated for use in the preparation or treatment of ultrapure water include resins made from styrene-based polymers (e.g., polystyrene sulfonate). Ion exchange resins may be of the type known as a "strongly acidic cation exchange resin," a "strongly basic anion exchange resin," or a type comprising a mixture of the two. Ion exchange resins may be in the form of a gel, may be porous or non-porous, or may be in the form of solid particles (e.g., beads or pellets). Some ion exchange resins can be regenerated after a period of use (referred to as "regenerable"), and other resins cannot be regenerated. As shown in FIG5A , a filtration system 300 includes a filtration apparatus 310, which includes a housing 308 containing and enclosing a porous filtration membrane 302, as described above. The porous filtration membrane 302 comprises a base membrane and attached amino polyol ligands. In some embodiments, a composite membrane, such as composite membrane 150 described above, can be used as the filtration membrane placed in the filtration apparatus 310 shown in FIG5A and FIG5B . A filtration apparatus 320 is connected in series with and downstream of the filtration apparatus 310 and comprises an ion exchange resin 322. During operation of the filtration system 300, source water 316 flows into the inlet 306 of the filtration apparatus 310 and then passes through the filtration membrane 302. As the source water passes through the membrane 302, metal-containing contaminants are removed from the source water. The filtered source water then passes through a conduit 328 and into the housing 324 of the filtration apparatus 320. The source water passes through, through, or between the solid particles (e.g., beads, pellets) of the ion exchange resin 322, resulting in additional amounts of impurities being removed from the source water. Example ion exchange resins can be used to remove large amounts of dissolved metal contaminants (such as dissolved iron, titanium, and boron), as well as other metals (which can be anionic, cationic, or neutrally charged). After passing through the filtration device 320 and the ion exchange resin 322, the source water exits the housing 324 as purified water 340, which can be considered ultrapure water. Figure 5B shows an alternative filtration system 300 comprising filtration apparatus 310 and filtration apparatus 320 in a reverse order. In Figure 5B, source water first passes through filtration apparatus 320 and then passes through filtration apparatus 310. A filtration membrane of the present invention, or a composite membrane comprising such a filtration membrane, can be used to filter a water source ("source water") containing a relatively low level of impurities, for example, a water source that has been substantially purified or previously treated by a filtration or purification step. In an exemplary method, source water that has been previously treated to remove impurities can be provided, and the source water can be treated using a filtration membrane as described to remove a certain amount of remaining impurities (such as dissolved metal impurities) to produce further purified water (i.e., "purified water" or "ultrapure water"). Specifically, a porous polymer filtration membrane as described can be used to remove one or more dissolved and / or suspended metal-containing impurities from the source water flowing through the membrane. Solid particulate impurities can be removed from the source water by a screening mechanism, a non-screening mechanism, or both, and dissolved metal impurities can be removed from the source water by a non-screening mechanism that involves binding the dissolved impurities to the hydroxyl groups of the aminopolyol ligands of the filtration membrane. Relatively large metal-containing particles can be captured by the filter by size restriction based on pore size, and metal ions that are originally small enough to pass through the pores of the filter membrane are captured by chemical interaction with the aminopolyol ligands that are attached and immobilized at the membrane surface. In one particular method, a filtration membrane comprising aminopolyol ligands attached to a base membrane as described can be used to remove metal contaminants (dissolved metals and metal ions) from source water containing desirably reduced levels of such materials, for example, to use the water in a desired manufacturing process (e.g., a semiconductor or microelectronic device manufacturing process). Metal contaminants ("impurities") include dissolved metals and metal compounds (such as boron, iron, titanium, silicon, other dissolved metals, and metal compound particles (e.g., colloidal or solid silica)) and can be charged (ionic, e.g., anionic or cationic) or uncharged (non-ionic, neutrally charged). The source water may be water that has been previously treated to remove contaminants, particles, sediments, as a step to treat the water to a desired high or very high level of purity, for example, to produce what is known as ultrapure water. Ultrapure water is produced by treating a raw (impure) water source (such as river water, groundwater, or industrial water) through a "pretreatment" process to remove significant amounts of suspended solids and organic matter from the raw water, producing what is known as "primary pure water." Primary pure water may exhibit one or more physical properties or impurity levels of ultrapure water (see Table 1 below), but may also benefit from additional treatment to remove a portion of remaining impurities, such as dissolved metals or dissolved, solid, or colloidal silica. Primary pure water may be treated through one or more additional filtration or purification steps to remove very high levels of remaining impurities from the water. In the subsequent steps of preparing ultrapure water, the primary pure water can be treated by any one or more steps such as ultraviolet irradiation, ion exchange, electrodeionization (EDI), reverse osmosis (RO), degassing, ultrafiltration (using a membrane), etc. to remove a large number of trace impurities that may be present in the primary pure water, such as trace ions, organic matter, fine particles, dissolved gases, etc. The impurity content of ultrapure water can be measured through special measurements of total organic carbon (TOC), resistivity and conductivity, total solids content, pH, and specific ions. A water source described herein may be a water source referred to as "primarily pure water," which is water that has undergone at least one purification (e.g., filtration) step to produce ultrapure water. Alternatively, a water source may be a water source that has undergone a first purification step to form "primarily pure water" and one or more additional purification steps selected from ultraviolet irradiation, ion exchange, reverse osmosis, ultrafiltration (using a membrane), or two or more of these. This water source may still contain trace amounts of dissolved metal-containing contaminants (such as dissolved boron, iron, titanium, or silicon) and may also contain trace or small amounts of solid particles, such as silica particles. A filtration membrane, filtration device, or filtration system described herein can be used to remove at least a portion of the remaining contaminants. The described method can effectively produce ultrapure water that exhibits levels of one or more of the following impurities: surface 1 Ultrapure water is commonly used in semiconductor applications with concentrations of individual metal impurities of 0.01 μg / L or less. Recently, even higher levels of purity, such as individual metal impurity levels of 1 ng / L or less, have become necessary. In one example, a filtration membrane described can be used to supply pure water (eg, ultrapure water) to a semiconductor or microelectronic device processing system during manufacturing, such as as rinse water to clean or prepare the surface of a microelectronic device substrate or a semiconductor device substrate. FIG6 illustrates a semiconductor manufacturing system 400 including chamber 402, in which a microelectronic component, such as an integrated circuit or semiconductor material, is fabricated. Chamber 402 is capable of receiving purified water (e.g., ultrapure water) to process (e.g., wash) a microelectronic device or semiconductor substrate contained in chamber 402. The purified water may be provided from source water contained in and delivered from source 412, and further processed using filter 435. The movement of the source water through conduit 416 may be affected by pump 414. Valve 430 is in fluid communication with conduit 416 and regulates the flow of source water into filter 435 and subsequently into chamber 402 through conduit 438. Filter 435 may comprise a filter membrane as described herein, including a base membrane with an aminopolyol ligand attached thereto. One or more additional filtering or purification devices may be included in series with filter 435 to remove impurities other than or in addition to those removed by filter 435. The optional additional filtering device (not shown) may be one or more of an ion exchange resin, ultraviolet radiation equipment, reverse osmosis equipment, etc., which may be upstream or downstream of the filter 435. In use, source water flows from source 412 through pump 430 and through filter 435, which removes a certain amount of trace contaminants, such as dissolved metal-containing contaminants (e.g., boron, silicon, etc.). The source water may also flow through an optional ion exchange system, and the water filtered by filter 435 and the optional ion exchange system may be used in a processing step performed in chamber 402, such as for washing a surface of a microelectronic device or semiconductor device substrate. Examples Particle retention test The filter membranes described herein are tested for filtration efficiency, including particle retention. Particle retention can be assessed by measuring the number of test particles removed from a fluid stream by a membrane placed in the fluid stream. Particle retention can be measured by passing a test stream containing a known amount (concentration) of test particles (a collection of particles of known composition, average size, and size distribution) through the membrane at a constant flow rate and collecting the permeate to measure the particle content of the permeate. Testing can be performed at a range of particle coverage levels of the filter (referred to as "filter coverage," e.g., 0.05 monolayer, 0.1 monolayer, and 0.2 monolayer coverage, i.e., 5% filter coverage, 10% filter coverage, and 20% filter coverage). The concentration of test particles in the filtrate (or "permeate") can be calculated from the permeate absorbance. Next, based on a particle concentration in the feed ([feed]) relative to the particle concentration in the filtrate ([filtrate]), the particle retention was calculated using the following equation: Particle retention = ([feed] - [filtrate]) / [feed] x 100 Particle retention testing of the filter membranes described herein was performed using the SEMI C79 test method (August 2019). Figure 7 is a schematic diagram of an effective test method (see https: / / store-us.semi.org / products / c07900-semi-c79-guide-to-evaluate-the-efficacy-of-sub-15-nm-filters-used-in-ultrapure-water-upw-distribution-systems). 7, the test was performed using the following materials, equipment, and conditions: Flush flow rate: 10 liters per minute (LPM) Flow rate during test: Based on membrane surface area (in our test: 11.2 LPM) Particle type: SiO 2. Particle size: 6 to 32 nm (polydisperse). Measurement tool: DMA / CPC-based LNS. Target challenge: 1.5E9 particles ≥ 6 nm. Challenge filter: DMA = Differential Mobility Analyzer, CPC = Condensation Particle Counter, LNS = Liquid Nanosizer. Two filters were tested: Filter 1 (comparative) and Filter 2 (invention). Filter 1 is made from a polytetrafluoroethylene (PTFE) based membrane with non-uniform morphology and is not treated to contain any amino polyol ligands, such as a chemically attached quaternary ammonium salt. Filter 1 properties include: bubble point: 30 to 60 psi, dye binding capacity < 0.1 µg / cm 2. Filter 2 is the base membrane of filter 1 modified to include quaternary ammonium attached to the polymer surface. Filter 2 properties include: bubble point: 30 to 60 psi, dye binding capacity (DBC): at least 10 µg / cm 2 . The test results are shown in Figures 8, 9, and 10. As shown in FIG8 , the retention of the comparative filter 1 on the test particles within a particle diameter range is well below 100% for all diameters, while the retention of the filter 2 of the present invention on the test particles within the particle size range is 100% for all diameters. As shown in Figure 9, for all diameters and filter coverage amounts, comparative filter 1 retained test particles well below 100% over a range of particle diameters and a range of filter coverage (percent monolayer). In contrast, Figure 10 shows that for inventive filter 2, particle retention was 100% for all particle diameters and over a range of filter coverage (percent monolayer). Static test of boron removal The membranes described herein are tested for their ability to remove boron under static immersion (non-flow) conditions. With this test, a sample of a filter membrane is exposed to a known volume of a liquid test solution ("spiked feed") containing a known amount (concentration) of dissolved boron. The sample filter membrane is allowed to contact the spiked feed (immersed in the spiked feed) for a period of time to allow the boron to be removed from the spiked feed by a non-sieving filtration mechanism, for example, by electrostatic or chemical attraction, adsorption, or another type of attachment or attraction of boron to a surface of the sample filter membrane. After allowing a certain amount of time for non-sieving attraction of boron to the filter membrane, the boron concentration in the liquid test solution in contact with the filter membrane sample is measured. A decrease in the boron concentration in the liquid test solution is indicative of the amount of boron removed by the sample filter membrane. Three sample filter membranes were tested: Technology A (inventive), Technology B (comparative, not inventive), and Technology C (comparative, not inventive). The Technology A membrane is made from a polyethylene ultra-high molecular weight polyethylene (UPE) base film with a substantially uniform morphology, an average pore size of 0.2 μm, and a thickness of 80 μm. The membrane is surface-modified with a stabilized N-methyl-D-glucanamine coating. The amount of N-methyl-D-glucanamine modification is quantified by performing a DBC test, which indicates the amount of accessible charged amines on the membrane surface. The DBC for Technology A was determined to be 120 μg / cm 2 . The Technology B membrane is prepared from a PTFE membrane surface modified with a stable quaternary ammonium salt coating having a substantially uniform morphology with an average pore size of 30 nm, a thickness of 25 to 60 microns, and a viscosity of at least 10 µg / cm 2 DBC. Technology C is an ultra-high molecular weight polyethylene membrane modified with sulfonic acid functional groups, which has a substantially uniform morphology and an average pore size of 0.2 microns and a thickness of 80 microns. The UPE membrane modified with sulfonic acid functional groups exhibits 4.2 meq / m 2 The ion exchange capacity. The sample filter membrane was a 47 mm circular specimen. The test solution volume was 25 ml. The sample filter membrane was immersed in the test solution for 16 hours. The boron concentration in the liquid test solution was measured using ICP-MS. The results are shown in Figure 11. As shown, the filter membrane of the present invention (Technique A) removed essentially all of the dissolved boron, while the comparative, non-inventive filter membranes (Technique B and Technique C) removed only a small portion of the dissolved boron in the test solution. Attached N- methyl -D- Determination of the dye binding capacity of positively charged membranes of dextran amine The examples demonstrate how the presence of positive charges on a porous membrane can be approximated by measuring the uptake of the negatively charged dye molecule Ponceau S. This method is used to measure the amount of charge applied to a surface-modified UPE membrane (Technique A). First, a coupon of known area is placed in a 50 mL conical tube containing 50 mL of a diluted (0.005% by weight) Ponceau S Red dye (Sigma Aldrich) feed solution in 50% isopropanol, and the tube is immediately capped and rotated for 16 hours. After rotating for 16 hours, the membrane coupon is removed from the Ponceau S solution. By determining the difference in UV absorbance between the original solution and the rotated solution, a final "dye binding capacity" (DBC) can be calculated and expressed in μg / cm 2 This number is an approximation of the level of charged functional groups on the surface of a membrane and is related to the level of ion exchange capacity of the membrane. In the case of the presence of a charged amine due to the presence of an attached N-methyl-D-glucanamine, DBC indicates the amount of N-methyl-D-glucanamine attached to the coating on the membrane surface. The Ponceau S DBC of an unmodified UPE membrane (base membrane) is 0.00 μg / cm 2 The DBC of the N-methyl-D-glucanamine surface modified membrane was determined to be 120 μg / cm 2 The same method can be used to determine the DBC of the other films in these examples. Dynamic testing of boron removal Testing Technique A: A membrane's ability to remove dissolved metals, including boron, under dynamic conditions. In this test, a sample (test piece) of a filter membrane is held in a stream of a liquid test solution ("feed") containing a known amount (concentration) of dissolved metals, including boron. The test solution flows through the sample filter membrane for a set amount of time. See Figure 12. After the selected amount of time, a sample of the filtrate is obtained and the concentration of dissolved metals in the filtrate is measured. A decrease in the concentration of dissolved metals in the filtrate relative to the amount of dissolved metals in the test solution indicates the amount of dissolved metal removed by the sample filter membrane. Referring to Figure 13, the test was performed using the following materials, equipment, and conditions: Flow rate: 10 mL / min (single pass, monitor, and control) Membrane format: Ø47 mm coupon Test metal and feed concentrations: B: 5 parts per billion (ppb) Ti: 3.6 parts per billion (ppb) (high challenge) Fe: 6.4 parts per billion (ppb) (high challenge) Fe: 0.68 parts per billion (ppb) (low challenge) Ni: 0.13 parts per billion (ppb) (low challenge) Cu: 0.13 parts per billion (ppb) (low challenge) Sampling method: time-based Sampling location: downstream of the membrane Measurement tool: ICP-MS The concentrations of dissolved metals in the test solution and filtrate were measured using ICP-MS. The results of the effectiveness of removing dissolved boron are shown in Figure 13. As shown, the filter membrane of the present invention (Technology A) removed essentially the entire amount of dissolved boron within the sampling times of 5, 10, 15 and 20 minutes. Figures 14 and 15 show the effectiveness of removing other dissolved metals at a "high challenge" feed concentration and a "low challenge" feed concentration, respectively. The tests demonstrated that the Technology A membrane was able to remove significant amounts of these metals from a test solution under both high and low challenge conditions (>80% Fe, >95% Ti, >50% Ni, >60% Cu). Dynamic test of boron capacity Using a similar dynamic test configuration and test conditions, a single test was conducted over an extended period on a Tech A sample filter membrane to evaluate its capacity to remove boron from a test solution. Flow rate: 10 mL / min (single pass, monitoring and control). Membrane format: 90 mm disk. Boron feed concentration: 5 parts per billion (ppb). Sampling method: Time-based. Sampling location: Downstream of the membrane. Measurement tool: ICP-MS. Dissolved metal concentrations in the test solution and filtrate were measured and evaluated using ICP-MS. Figure 16 shows the results of the ability to remove and contain boron from a test solution. The test showed that the Technology A filter membrane was able to remove 100% of the boron from the test solution even after 2 μg of boron had passed through the membrane. This is equivalent to removing approximately 800 μg of boron using a 10-inch filter cartridge. While several illustrative embodiments of the present invention have thus been described, those skilled in the art will readily appreciate that other embodiments may be made and used within the scope of the appended claims. Numerous advantages of the invention encompassed by this document have been set forth in the foregoing description. However, it should be understood that the present invention, in many aspects, is merely illustrative. Of course, the scope of the present invention is defined by the language expressed in the appended claims. 10: Base membrane 100: Filter device 102: Porous polymer filter membrane 104: Housing 106: Inlet port / inlet 108: Outlet 110: Frame portion 112: Frame portion 114: Head space 116: Arrow 120: Rear space 122: Edge 124: Input-facing surface 126: Output-facing surface 150: Composite membrane 152: Upstream surface 154: Upstream non-filtering support membrane 156: Filter membrane 158: Filter membrane 160: Downstream non-filtering support membrane 162: Downstream surface 200: Filter device 202: First porous polymer membrane 204: Housing 206: Inlet port 208: Outlet port 210: Frame portion 212: Frame portion 214: Head space 220: Rear space 222: Second porous polymer membrane 300: Filtration system 302: Porous filter membrane 306: Inlet 308: Housing 310: Filtration device 316: Source water 320: Filtration device 322: Ion exchange resin 324: Housing 328: Conduit 340: Purified water 400: Semiconductor manufacturing system 402: Chamber 412: Source 414: Pump 416: Conduit 430: Pump 435: Filter 438: Conduit A more complete understanding of the invention may be gained from the following description of various illustrative embodiments when considered in conjunction with the accompanying drawings, which are schematic and not necessarily drawn to scale. FIG1 shows an aminopolyol ligand relative to a base membrane, as described. FIG2 shows an example filter assembly as described. FIG3 shows a diagram illustrating an example composite filter. FIG4 shows an example filter assembly as described. 5A and 5B show example components of the described filtration system. FIG6 schematically illustrates semiconductor manufacturing equipment for use with one of the described filtration membranes and methods. FIG. 7 schematically shows a test system according to one of the examples herein. FIG8 , FIG9 , FIG10 and FIG11 show the test data of the filter membrane of the present invention and the comparative filter membrane. FIG12 schematically shows a test system according to one of the examples herein. FIG13 , FIG14 , FIG15 and FIG16 show the test data of the filter membrane of the present invention. While the present invention is susceptible to various modifications and alternative forms, details thereof have been shown by way of example in the drawings and will be described in detail. However, it should be understood that there is no intention to limit the aspects of the present invention to the particular illustrative embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention. 10: basement membrane

Claims

1. A system for removing an impurity from a source water stream, the system comprising: (i) A first porous polymer filter membrane having an amino polyol ligand comprising one of three or more hydroxyl groups attached thereto; (ii) a second porous polymer filter membrane configured to remove solid particulate contaminants; and (iii) an ion exchange resin.

2. The system of claim 1, wherein the amino polyol ligand system comprising three or more hydroxyl groups is N-methyl-D-glucosamine.

3. The system of claim 1, wherein the second porous polymer filter membrane has a quaternary ammonium salt attached thereto.

4. The system of any one of claims 1 to 3, wherein the first porous polymer filter membrane has a pore size characterized by a bubble point in the range of 4 psi to 160 psi, the bubble point being measured using ethoxy-nonafluorobutane HFE-7200 at a temperature of 20 to 25°C.

5. The system of any one of claims 1 to 3, wherein the first porous polymer filter membrane is characterized by having a dye binding capacity greater than 100 µg / cm².

6. The system of any one of claims 1 to 3, wherein the first porous polymer filter membrane is characterized by having a dye binding capacity of 120 µg / cm².

7. The system of any one of claims 1 to 3, wherein the first porous polymer filter membrane comprises a polyolefin or a halogenated polymer.

8. The system of any one of claims 1 to 3, wherein the first porous polymer filter membrane comprises ultra-high molecular weight polyethylene.

9. The system of any one of claims 1 to 3, wherein the first porous polymer filter membrane comprises polytetrafluoroethylene.

10. The system of any one of claims 1 to 3, wherein the second porous polymer filter membrane has a pore size characterized by a bubble point in the range of 4 psi to 160 psi, the bubble point being measured using ethoxy-nonafluorobutane HFE-7200 at a temperature of 20 to 25°C.

11. The system of claim 10, wherein the foaming point is in the range of 30 psi to 60 psi.

12. The system of any one of claims 1 to 3, wherein the second porous polymer filter membrane is characterized by having a dye binding capacity of at least 10 µg / cm².

13. The system of any one of claims 1 to 3, wherein the second porous polymer filter membrane comprises a polyolefin or a halogenated polymer.

14. The system of any one of claims 1 to 3, wherein the second porous polymer filter membrane comprises ultra-high molecular weight polyethylene.

15. The system of any one of claims 1 to 3, wherein the second porous polymer filter membrane comprises polytetrafluoroethylene.

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