Filtration membrane, system, and method for producing purified water

Abstract

To provide a system for preparing purified water capable of being used in a process of manufacturing electronic and semiconductor devices.SOLUTION: A system with a first porous polymer filter membrane having an aminopolyol ligand useful for producing purified (e.g. ultrapure) water, a second porous polymer filter membrane configured to remove solid particulate contaminants, and an ion exchange resin, and related methods are described.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to filter membranes, related filter assemblies and filtration systems, and related methods useful for the production of purified (e.g., ultra-pure) water, including membranes, systems, and methods useful for the preparation of purified water that can be used for processing (e.g., rinsing) semiconductor and microelectronic substrates, components, and devices. [Background technology]

[0002] High purity water, including water sometimes referred to as "ultrapure" water ("UPW"), is important for a variety of commercial applications including semiconductor processing (e.g., the manufacture of semiconductor devices, liquid crystal displays, silicon wafers, printed circuit boards, and other electronic and microelectronic devices), nuclear power plant operation, and pharmaceutical manufacturing.

[0003] Purified water used in semiconductor processing is useful in semiconductor and microelectronic processing (as one example) as a rinse water 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. As a use, ultrapure water can be used for in-process microelectronic device wet etching and cleaning ("WEC"), photolithography, and chemical mechanical polishing ("CMP"). Water is used to process microelectronic devices or semiconductor substrates and must be of very high purity because impurities in the water that are left on the substrate surface affect the yield and short-term / long-term performance of the resulting semiconductor or microelectronic device made from the substrate.

[0004] Filtration systems for preparing ultrapure water must remove impurities (aka "contaminants") to very high purity and for manufacturing efficiency, must do so over long periods of time while minimizing the need to replace filtration elements. Removing and replacing filtration elements in filtration systems that supply ultrapure water to semiconductor processing equipment may require the equipment to be shut down for the period required to remove and replace the filtration elements, i.e., the "changeover" period. Changeover periods are costly in terms of lost semiconductor processing equipment time, resulting in reduced processing efficiency and increased overall costs. The frequency and duration of changeovers can affect the efficiency of equipment that directly uses the purified water and can also affect processes that run downstream of the directly affected equipment.

[0005] Ultrapure water used in semiconductor processing is understood to be not completely pure, but to contain very low levels of contaminants including silica particles (colloidal and hard SiO2 particles), organics (dissolved and undissolved), and dissolved metals or metal-containing compounds such as boron, silicon (e.g., as SiO2), iron, and titanium. Boron and silica impurities are particularly problematic because current filtration systems are not effective enough to remove and retain boron and silica (e.g., colloidal and solid silica particles), or may be effective over a not long enough operating life to remove these impurities from water streams.

[0006] A common design for ultrapure water generating facilities includes 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 hold trace ionic impurities, removing the impurities from the water flowing through the bed of polymer beads. In such ion exchange systems, after a period of time in which the system is used to remove boron, silicon (e.g., solid and colloidal silica particles, or dissolved silica), or both from a water source, the capacity of the ion exchange resin bed to remove and contain (retain) the boron, silicon, or both becomes exhausted. The ability of the ion exchange system to continue removing additional amounts of boron or silicon (silica) from the water becomes exhausted and it no longer removes boron or silicon from the water stream. When this occurs, these impurities begin to pass through the ion exchange system and "leak" out of the system to downstream equipment as undesirable impurities.

[0007] As the integration of microelectronic devices becomes more complex, trace amounts of contaminants in ultrapure water become more and more significant. Thus, ultrapure water with higher levels of purity is required to meet goals (economic and otherwise) for wafer die yield and overall reliability of semiconductor or microelectronic devices. Summary of the Invention

[0008] The following description relates to a porous polymeric filter membrane that includes a porous polymeric base membrane and an aminopolyol ligand ("aminopolyol" or "aminopolyol ligand") that contains at least three hydroxyl groups attached to the base membrane. The description also relates to filter assemblies and filtration systems that include this type of filter membrane, and methods of using the filter membrane, filter assemblies, and filtration systems to filter a water source ("source water") to form purified (e.g., ultrapure) water.

[0009] Filter membranes as described are useful for removing impurities from water sources, and are particularly useful for removing metallic impurities such as dissolved boron and silicon (e.g., as SiO2) from water sources to form purified (e.g., ultrapure) water. Purified water prepared according to the methods described and containing very low amounts of boron and silicon can be useful in industrial processes, including, but not limited to, semiconductor and microelectronic manufacturing processes, such as for rinsing the surfaces of semiconductor and microelectronic substrates.

[0010] As used herein, the term "ultrapure water" is given its meaning commonly used in the semiconductor processing industry and refers to water that has been processed to an extremely high level of purity with respect to a group of contaminant types including organic and inorganic compounds, dissolved and particulate matter, volatile and nonvolatile impurities, charged (anionic, cationic) and nonionic impurities, reactive and inert impurities, hydrophilic and hydrophobic impurities, and dissolved gases. Ultrapure water is water that has been processed to remove organic particles and dissolved gases, as well as other dissolved trace impurities. Ultrapure water is generally processed through three processing stages including a pretreatment stage to produce purified water, a primary stage to further purify the water, and a final "polishing" stage.

[0011] There are various published standards to specify the levels of impurities present in ultrapure water. For microelectronic applications, these groups include the Semiconductor Equipment and Materials Association (SEMI) (microelectronics and photovoltaics), the American Society for Testing and Materials (ASTM International) (semiconductors, power), the Electric Power Research Institute, the American Society of Mechanical Engineers (ASME) (power), and the International Association of Water and Steam Properties (IAPWS) (power). Pharmaceutical plants follow water quality standards developed by pharmacopoeias, three examples of which are the United States Pharmacopoeia, the European Pharmacopoeia, and the Japanese Pharmacopoeia.

[0012] General requirements for ultrapure water are documented by ASTM D5127, "Standard Guide for Ultra-Pure Water Used in the Electronics and Semiconductor Industries" and SEMI F63, "Guide for ultrapure water used in semiconductor processing."

[0013] In one aspect, the present disclosure relates to a polymeric filter membrane. The membrane comprises a porous polymer base membrane and an aminopolyol ligand having three or more hydroxyl groups attached to the polymer base membrane.

[0014] In another aspect, the present disclosure relates to a system useful for removing impurities from a source water stream. The system includes a porous polymer-based membrane and a polymeric filter membrane that includes an amino polyol ligand having three or more hydroxyl groups bound to the polymeric base membrane. The system also includes an ion exchange resin and a source water stream passing through the polymeric filter membrane and the ion exchange resin.

[0015] In yet another aspect, the disclosure relates to a method for removing impurities from a source water stream, the method comprising passing the source water through a polymeric filter membrane comprising a porous polymeric base membrane and an amino polyol ligand having three or more hydroxyl groups bound to the polymeric base membrane.

[0016] The present disclosure may be more fully understood in consideration of the following description of various illustrative embodiments in conjunction with the accompanying drawings, in which: The figures are schematic and are not necessarily to scale. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 shows aminopolyol ligands to a base membrane as described. [Diagram 2] FIG. 1 illustrates an exemplary filter assembly of the present specification. [Diagram 3] FIG. 2 illustrates an exemplary composite filter of the present specification. [Figure 4] FIG. 1 illustrates an exemplary filter assembly of the present specification. [Figure 5A] FIG. 1 illustrates exemplary components of a filtration system herein. [Figure 5B] FIG. 1 illustrates exemplary components of a filtration system herein. [Figure 6] 1A-1C are schematic diagrams illustrating semiconductor manufacturing equipment and methods for use with filter membranes as described. [Figure 7] FIG. 1 is a schematic diagram of a test system according to an embodiment of the present disclosure. [Figure 8] FIG. 1 shows test data for a filter membrane of the present invention and a comparative filter membrane. [Figure 9] FIG. 1 shows test data for a filter membrane of the present invention and a comparative filter membrane. [Figure 10] FIG. 1 shows test data for a filter membrane of the present invention and a comparative filter membrane. [Figure 11] FIG. 1 shows test data for a filter membrane of the present invention and a comparative filter membrane. [Figure 12] FIG. 1 is a schematic diagram of a test system according to an embodiment of the present disclosure. [Figure 13] FIG. 1 shows test data for a filter membrane of the present invention. [Figure 14] FIG. 1 shows test data for a filter membrane of the present invention. [Figure 15] FIG. 1 shows test data for a filter membrane of the present invention. [Figure 16] FIG. 1 shows test data for a filter membrane of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] While the present disclosure 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. It should be understood, however, that it is not intended to limit aspects of the disclosure to the specific illustrative embodiments described. On the contrary, the intent is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.

[0019] The following description relates to a filter membrane that includes a porous polymer-based membrane and an amino polyol ligand ("amino polyol" or "amino polyol ligand") that contains at least three hydroxyl groups as part of the filter membrane. The description also relates to filter assemblies and filtration systems that include this type of filter membrane, as well as methods of using the filter membrane, filter assemblies, and filtration systems to filter a source of water to form purified (e.g., ultrapure) water.

[0020] The filter membranes as described can be used to remove impurities from water sources, and are particularly useful for removing metal impurities such as boron and silicon (e.g., dissolved SiO2, or colloidal or solid SiO2 particles) from water sources to form purified (e.g., ultrapure) water. Purified water prepared according to the described methods and containing very small amounts of boron and silicon (e.g., silica, SiO2) can be used in industrial processes including, but not limited to, semiconductor and microelectronic manufacturing processes, such as for rinsing the surfaces of semiconductor and microelectronic substrates. The filter membranes as described can be configured for use in microelectronic or semiconductor device manufacturing systems as a point-of-use filtration system that processes a source of water immediately upstream of the manufacturing system to provide purified (e.g., ultrapure) water for use in the manufacturing system. Alternatively, the filter membranes, filter assemblies, or filtration systems as described can be used to generate purified water (e.g., ultrapure water) for storage in a storage vessel for any storage, transportation, and eventual later use.

[0021] The membrane as described includes a porous polymer base membrane to which the aminopolyol ligand is directly or indirectly bound.The base membrane (sometimes referred to as "base" for short) may be a membrane in the form of a polymer sheet (i.e., a flat, planar, double-sided porous membrane) made from any useful polymer material or combination of materials.Exemplary base membranes can be made from polymer materials that are known to be useful for porous filtration membranes and can be chemically modified to bind aminopolyol ligands to their surfaces.The base membrane may be made from a polymer that contains reactive sites to which the aminopolyol ligand can be bound, or can be chemically coated or modified in other ways to provide reactive sites to which the aminopolyol ligand can be bound.

[0022] An exemplary base membrane may be formed from one or more polymeric materials, for example, a single polymeric material, a mixture of different polymeric materials, or polymeric and non-polymeric materials.

[0023] Polymeric materials that can be used to form the base membrane include a variety of polymers, including hydrophobic polymers such as polyolefins or halogenated polymers. Exemplary polyolefins include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polybutene (PB), polyisobutylene (PM), and copolymers of two or more of ethylene, propylene, and butylene. In certain embodiments, the base membrane may include ultra-high molecular weight polyethylene (UPE). Ultra-high molecular weight polyethylene filter materials, such as UPE membranes, typically have a molecular weight of about 1×10 6 More than daltons (Da), e.g., about 1 × 10 6 ~9×10 6 Da, or 1.5 × 10 6 ~9×10 6They are formed from resins having molecular weights in the Da range. Crosslinking between polyolefin polymers, such as polyethylene, can be promoted by the use of heat or crosslinking chemicals, such as peroxides (e.g., dicumyl peroxide or di-tert-butyl peroxide), silanes (e.g., trimethoxyvinylsilane), or azoester compounds (e.g., 2,2'-azo-bis(2-acetoxy-propane).

[0024] Exemplary halogenated polymers include polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), fluorinated ethylene polymer (FEP), polyhexafluoropropylene, and polyvinylidene fluoride (PVDF).

[0025] In other embodiments, the base membrane may be made from a polymer selected from polyamide, polyimide, polysulfone, polyethersulfone, polyarylsulfone, polyamide, polyacrylate, polyester, nylon, cellulose, polycarbonate, or combinations thereof.

[0026] A base membrane comprising any one or combination of these polymers may comprise, consist of, or consist essentially of any one or combination of these polymers. A base membrane consisting essentially of a polymer or combination of polymers is a base membrane that contains the polymer or combination of polymers and no more than trace amounts of other materials, for example no more than 5, 2, 1, 0.5, or 0.1 weight percent of other materials.

[0027] Specific examples of polymers useful for the preparation of porous polymeric filter membranes are described in U.S. Patent Publication No. 2020 / 0254398, which is incorporated by reference in its entirety.

[0028] In some implementations, the polymeric material of the base membrane can be chemically modified to facilitate modification of the base membrane with an aminopolyol ligand. The aminopolyol ligand can include an amine group that can facilitate attachment to the polymeric material of the base membrane. If the polymeric material is not inherently amine reactive, it can be modified, such as by halogenation or haloalkylation, to provide a surface reaction chemistry for attachment of the aminopolyol ligand.

[0029] In some implementations, the polymeric material of the base membrane is halogenated to provide amine reactive sites. For example, polyethylene can be chlorinated by reacting gaseous chlorine, optionally diluted with an inert gas, with solid polyethylene powder at temperatures above 50° C. (see, for example, U.S. Pat. No. 2,928,819).

[0030] In another implementation mode, the polymer of the base membrane can be haloalkylated, for example chloromethylated. Chloromethylation is a known technique used to modify polymers, and generally uses chloromethylation reagents (e.g., bis-chloromethyl ether (BCME), chloromethyl methyl ether (CMME), formaldehyde / methanol / hydrogen chloride / chlorosulfonic acid). Lewis acids such as zinc chloride, zinc oxide, or ferric chloride and Friedel-Crafts catalysts can be used with chloromethylation reagents at high temperatures to modify the polymer. (See, for example, U.S. Patent Publication No. 2003 / 0018091 (Pafford et al.) and WO 2008 / 144115 (Harris et al.)). To provide the ligand of the present disclosure on polymeric materials, the haloalkyl group of the haloalkyl-modified filter material can be reacted with amine polyol or amine polyphosphonic acid to covalently bond the ligand to the surface of the filter material.

[0031] In another implementation, amino polyol ligands can be attached to the filter material by binding with a reactive crosslinking coating. For example, the polymeric material can be coated with an amine-reactive polymer, such as poly(vinylbenzyl chloride), poly(epichlorohydrin), or epoxy resin. The coated polymeric material can then be crosslinked, and the remaining reactive sites can be used to bind the desired ligand. For example, poly(vinylbenzyl chloride) can be dissolved in a suitable solvent, dried on a porous polymer base membrane, crosslinked with a diamine, polyamine, or any other multifunctional reactive crosslinking agent, and then attached with an amine-containing polyol ligand. Using a similar method, crosslinking and ligand attachment can occur simultaneously. Alternatively, the amine-reactive polymer can be crosslinked by irradiation or by using a photoinitiator crosslinking agent, and then attached with an amine-containing ligand.

[0032] In yet another implementation, the ligand binding can occur before coating on the polymer base membrane. 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 resulting aminopolyol ligand modified polymer can then be coated on the base membrane and dried. Any crosslinking technique can be used.

[0033] In another implementation, the base membrane 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 with an acrylamide, vinyl, or other suitable unsaturated group. An example of a reactive monomer with an aminopolyol is the reaction product of vinylbenzyl chloride and N-methylglucamine. The aminopolyol-containing monomer can be added to a monomer formulation containing a bifunctional 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 absorbed into the resulting monomer solution, it can be irradiated (ultraviolet, e-beam, gamma, etc.) to form a crosslinked coating with the desired aminopolyol ligand incorporated into the coating (see, for example, WO 2017 / 205722 (Jaber et al.)).

[0034] In another implementation, the desired amino polyol ligand can be attached to the polymeric material via grafting from a membrane. "Grafting from" can be achieved by irradiation of the polymeric material in the presence of a photoinitiator and an unsaturated monomer containing the desired amino polyol ligand (see, for example, WO 2016 / 081729 A1 (Jaber et al.)). In another implementation, the polymeric material can be attached with the desired amino polyol ligand via grafting from a membrane using electron beam or gamma irradiation. Grafting using electron beam or gamma irradiation can be achieved using techniques known as pre-irradiation grafting or co-irradiation grafting.

[0035] In another implementation mode, polymeric materials can be embedded with resin particles to form hybrid particle / membrane-based membranes. For example, porous poly(styrene-co-divinylbenzene) resin particles with desired amino polyol ligands can be introduced into the polymer mixture used for membrane extrusion or membrane casting. Using this method, the resulting porous polymer membrane has embedded therein the porous particles with desired amino polyol ligands. In some embodiments, the resulting membrane can have a tight particle-retaining membrane located downstream of the porous particle-containing membrane (see, for example, U.S. Patent Publication No. 2009 / 0039019A1 (Raman)).

[0036] The amount (concentration) of aminopolyol ligand introduced into the polymeric material of the base membrane can be sufficient to allow the aminopolyol ligand to be immobilized on the surface of the base membrane at a desired density. The ligand solution can be applied to the surface of the base membrane by any useful technique, such as spraying, dipping, soaking, etc. the base membrane in the solution. Desirably, the entire surface of the base membrane, such as all the inner surfaces of the porous filter membrane, can be contacted with the solution. If necessary, the application step can include manipulation of the filter material, for example by rolling or squeezing the porous filter material to wet all the surfaces of the porous filter.

[0037] Porous base membranes and filter membranes made from the base membrane by chemically bonding aminopolyol ligands to the base membrane can be described in terms of various physical characteristics of the porous filter membrane. As used herein, an exemplary porous base membrane of a porous filter membrane includes a porous solid in the form of a double-sided sheet having opposing surfaces (sides), a length and width extending along the two surfaces, and a thickness extending between the two opposing surfaces. A porous membrane contains porous (e.g., microporous) interconnected passages (pores, channels, voids) that extend from one surface of the membrane to the opposite surface of the membrane. The passages generally provide a tortuous channel or path through which the source water to be filtered must pass. Metal species of a size small enough to pass through the pores of the membrane can be captured on the membrane by interaction with the aminopolyol ligand, for example, a chelating interaction between the ligand and the metal. This is referred to as a "non-sieving filtration mechanism."

[0038] The porous membrane can also function to physically prevent particles (e.g., metal-containing particles) present in the source water from passing through the membrane. Particles larger than the pores can be prevented from entering the membrane or physically prevented from passing through the membrane by the structure of the membrane (i.e., removing the particles by a sieving-type filtration mechanism). As the source water passes through the membrane, water containing reduced amounts of contaminants removed by non-sieving or sieving mechanisms, e.g., reduced amounts of ionic metal species, reduced amounts of metal-containing particulates, or both, flows.

[0039] Thus, porous filter membranes as described, comprising a polymer-based membrane having amino polyol ligands attached thereto, can be effective not only in removing metal and metal ion contaminants from source water passing through the membrane, but also in removing materials that are physically too large in size to pass through the pores of the membrane.

[0040] The porous membrane of the present disclosure can be described with reference to one or more characteristics of the membrane.The exemplary porous polymer filter membrane as described can be characterized by physical characteristics including pore size, bubble point and porosity.For example, the membrane can be described in terms of bubble point, which is commonly used to reflect pore size.

[0041] The bubble point of a membrane is an indirect measurement of pore size based on the concept that for a particular fluid and pore size, at constant wetting of the membrane, the pressure required to force a gas bubble through a porous membrane is inversely proportional to the size of the membrane's pores. Methods for determining the bubble point can include wetting the 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 that are released from the opposite surface of the membrane. To determine the bubble point of a porous material, a sample of the porous material is immersed and wetted (e.g., 22 °C) in ethoxy-nonafluorobutane HFE 7200 (available from 3M) at a temperature of 20-25 °C. Compressed air is used to apply gas pressure to one side of the sample, and the gas pressure is gradually increased. The pressure difference at which the wetting flow is equal to half of the drying flow (the flow that does not wet the solvent) is called the bubble point.

[0042] In the exemplary filter membranes herein, the porous filter membrane (e.g., the base membrane, or the base membrane having aminopolyol ligands attached thereto) can have any useful bubble point, with examples of useful bubble points ranging from about 2 psi to about 400 psi, from about 4 psi to about 200, or preferably from about 4 psi to about 160 psi at a temperature of 22 degrees Celsius when ethoxy-nonafluorobutane (HFE-7200) is used as the wetting solvent.

[0043] Another characteristic of a porous filter membrane is the pore size, e.g., the average pore size, of the pores of the membrane. The pore size can be measured by known techniques such as mercury porosimetry (MP), scanning electron microscopy (SEM), liquid displacement spectroscopy (LLDP), or atomic force microscopy (AFM).

[0044] A porous membrane as described (e.g., a base membrane, or a base membrane with aminopolyol ligands attached thereto) can have any pore size that allows the filter membrane to be effective to function as a filter membrane. The pore size can be correlated with a bubble point determination. In some embodiments, the porous filter membrane can have an average pore size ranging from 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 being treated (such as the amount of metal impurities), and any particle size of the impurities.

[0045] Additionally, the present disclosure contemplates the use of polymer-based or porous filter membranes with generally uniform pore sizes resulting from a higher degree of pore symmetry throughout the thickness of the membrane, as well as membranes with non-uniform pore sizes (variable pore sizes) resulting from pore asymmetry. The pores can be isotropic or anisotropic, skinned or unskinned, symmetric or asymmetric, and any combination thereof.

[0046] The porous polymeric filter layer as described can have any porosity that allows the porous polymeric filter layer to be effective as described herein.Exemplary porous polymeric filter layers can have relatively high porosity, for example, at least 60, 70 or 80 percent porosity.As used herein, and in the art of porous bodies, the "porosity" of a porous body (sometimes referred to as porosity) 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 ratio of the volume of the voids of the body to the total volume of the body.A body with zero percent porosity is completely solid.

[0047] The porous membrane as described can be a sheet having any useful or desired geometric configuration suitable for use in the filter assembly used as described.Exemplary porous membranes can have a shape selected from a circle, a semicircle, an ellipse, a semi-ellipse, or a polygon, such as a square, a rectangle, a hexagon, or an octagon.The porous membrane can be in the form of a flat sheet, a corrugated sheet, a pleated sheet, and a hollow fiber, among others.

[0048] Porous membranes as described may be in the form of sheets having any useful thickness, for example in the range of 20 to 400 microns, for example 40 or 80 to 100 or 200 microns.

[0049] As described herein, the porous filter membrane comprises a base membrane made of a polymeric material, and an aminopolyol ligand ("aminopolyol" or "aminopolyol ligand") containing at least three hydroxyl groups is chemically added to the surface of the base membrane, such as n-methylglucamine. The aminopolyol ligand, such as n-methylglucamine, has been found to be effective when placed on the surface of a filter medium to remove metal ions from source water (e.g., by a non-sieving filtration mechanism) in a method for forming purified (ultrapure) water by filtering source water through a filter medium.

[0050] The aminopolyol ligand can be n-methylglucamine or another aminopolyol ligand effective for removing metal ions from the source water by filtration (e.g., by a non-sieving filtration mechanism). Specific examples of aminopolyol ligands other than n-methylglucamine are described in U.S. Patent Publication No. 2020 / 0254398, which is incorporated herein by reference in its entirety.

[0051] As described in Publication 2020 / 0254398, an "aminopolyol ligand" is a chemical moiety that includes a nitrogen and a polyol moiety that contains three or more hydroxyl groups. Examples of aminopolyols having three hydroxyl groups include 3-aminobutane-1,2,4-triol (threosaminitol), 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.

[0052] 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-bis(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, These include 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 (livemine); 1-amino-1-deoxypentitol), 5-aminopentane-1,1,1,5-tetrol, 6-aminohexane-1,2,3,4-tetrol, and 6-(methylamino)hexane-1,2,4,5-tetrol.

[0053] Examples of aminopolyols having five hydroxyl groups include 1-aminopentane-1,2,3,4,5 pentol, 1-(methylamino)hexane-1,2,3,4,6 pentol, 5-(methylamino)hexane-1,2,3,4,6 pentol, 6-aminohexane-1,2,3,4,5 pentol, 5-(methylamino)hexane-1,2,3,4,6 pentol, 6-(methylamino)hexane-1,2,3,4,5 pentol (n-methylglucamine), 1-deoxy-1-(methylamino)-D-glucitol), and 6-(butylamino)hexane-1,2,3,4,5 pentol.

[0054] Examples of amino polyols having six hydroxyl groups include 6-(3-hydroxypropylamino)hexane-1,2,3,4,5 pentol, 6-(2-hydroxyethylamino)hexane-1,2,3,4,5 pentol, 6-(2-hydroxyethylamino)hexane-1,2,3,4,5 pentol, 1-(propylamino)hexane-1,2,3,4,5,6-hexol, 6-(methylamino)hexane-1,1,2,3,4,5-hexol, 7-(methylamino)heptane-1,2,3,4,5,6-hexol, and 7-(propylamino)heptane-1,2,3,4,5,6-hexol.

[0055] Examples of aminopolyols having seven hydroxyl groups include 6-(2,3-dihydroxypropylamino)hexane-1,2,3,4,5-pentol, 1-(ethylamino)hexane-1,1,2,3,4,5,6-heptol, 1-(2-hydroxyethylamino)hexane-1,2,3,4,5,6-hexol, and 8-(methylamino)octane-1,2,3,4,5,6,7 heptol.

[0056] Examples of aminopolyols having more than seven hydroxyl groups include 6-(2,2,2 trihydroxyethylamino)hexane-1,2,3,4,5 pentol, 1-(2,3-dihydroxypropylamino)hexane-1,2,3,4,5,6-hexol, and 6-(2,3,4,5,6 pentahydroxyhexylamino)hexane-1,2,3,4,5 pentol.

[0057] The present disclosure also contemplates all enantiomers and stereoisomers of the amino polyols as described herein.

[0058] Exemplary filter membranes comprising a polymer base membrane chemically modified to include aminopolyol ligands can have aminopolyol ligands bound to the surface of the base membrane in a useful manner. Examples include porous polymer base membranes made of polyolefins (e.g., polyethylene) that are chemically modified by direct binding of aminopolyol ligands to the base membrane polymer, i.e., polyolefin. The filter membrane can have a surface that contacts the liquid source water during the filtration process, and the surface presents the bound aminopolyol ligands to the source water. In some examples, the aminopolyol ligand-modified surface of the filter membrane can be represented by the following formula: MF-NP, where MF is the material of the filter (e.g., polyolefin), N is nitrogen, and P represents the polyol portion of the aminopolyol ligand. In other examples, the aminopolyol ligand-modified surface can be represented by MF-LNP, where MF, N, and P have the definitions herein, and L is a chemical linker that connects the aminopolyol to the filter material. Exemplary aminopolyol ligands are chemically bound (i.e., covalently bound) to the polymer of the base membrane. In other embodiments, the 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. In this embodiment, the filter material is internally coated with a modified polymer coating that may be crosslinked.

[0059] FIG. 1 shows an example of an aminopolyol ligand (n-methylglucamine as illustrated) directly bonded to a polymer (eg, polyolefin) of a base membrane 10 .

[0060] The porous filter membrane can be part of a filter assembly that includes a housing that contains the filter membrane and passes liquid through the membrane for the filtration process. The filter membrane may be included as part of a filter cartridge or other filter product or assembly that acts as a housing. The housing that contains the filter cartridge and filter membrane can be fluid-tight separately from the inlet and outlet ports, allowing liquid to pass through the inlet port, pass through the membrane contained in the housing without bypassing the membrane, and then exit the housing through the outlet port. The housing can be included as a component of a larger filtration or water purification system that can further include multiple filtration or purification devices in series with each other.

[0061] Larger filtration systems include, for example, a filter membrane as described herein, in the flow path of the liquid (source water) as part of a filter assembly or as part of a filter cartridge, for passing at least a portion of the liquid flow through the filter membrane, so that the filter membrane removes a certain amount of impurities or contaminants from the liquid. Specifically, source water passing through a filter membrane as described herein can be effective in removing impurities selected from dissolved metals and metal ions (e.g., dissolved iron, titanium, and boron), dissolved silica, and particles of silica (colloidal or solid particles).

[0062] The structure of the filter assembly or filter cartridge may include one or more of a variety of additional materials and structures that support the filter membrane within the filter assembly or filter cartridge and allow fluid to flow from a filter inlet, through the filter material (e.g., filter membrane), and through a filter outlet. The filter membrane supported by the filter assembly or filter cartridge may be of any useful shape, such as a pleated cylinder, a cylindrical pad, a cylindrical sheet without one or more pleats (flat), a pleated sheet, etc.

[0063] Referring to Figure 2, there is shown a schematic diagram of one example of a filter apparatus and method for removing metal contaminants from a flowing liquid source water, where the source water is passed through a porous polymeric filter membrane containing an amino polyol ligand. As shown in Figure 2, the filter apparatus 100 includes a porous polymeric filter membrane 102 containing an amine polyol ligand bound to the surface of the porous polymer-based membrane. The filter apparatus 100 includes a housing 104 that provides the exterior structure of the filter apparatus 100 and fluid-tightly seals the interior of the filter that houses the filter membrane 102. The housing 104 can be of any shape and size, for example, cylindrical, polygonal, etc.

[0064] The filter device 100 includes an inlet port 106 for receiving source water to be filtered. The inlet port 106 can be configured to be connected to a fluid supply line that provides a flow of source water (not shown). Thus, the inlet port 106 can include valves, gaskets, etc. (not shown) to facilitate connection to a fluid source. The source water can flow through the inlet port 106 in the direction indicated by arrow 116 and into an input surface 124 of the porous polymeric filter membrane 102, an interior surface of the housing 104, and a headspace 114 defined by the inlet port 106.

[0065] The interior of the filter device 100 houses the filter membrane 102 in any suitable arrangement or configuration, with FIG. 2 showing the filter membrane 102 having a disk-like shape (a cross-sectional view is shown). One edge 122 of the filter membrane 102, such as the periphery of the membrane, can contact or otherwise form a liquid-tight seal with the interior surface of the housing 104. The filter membrane 102 also includes an input surface 124 that initially contacts the source water and an output surface 126 through which the treated (filtered) source water containing reduced amounts of contaminants (metals, metal ions, etc.) flows.

[0066] The filter device 100 optionally includes one or more structures that support the filter membrane 102 inside the filter device. Any configuration for supporting the filter membrane 102 may be used and may be useful for supporting the membrane 102, such as a frame, frame, bracket, clip, web, net, cartridge, or cage, or adhesive. As shown in FIG. 2, the filter device 100 includes a frame having frame portions 110 and 112, where the frame portion 110 is in contact with the inner surface of the housing 104 attached to the portion 112. The portion 112 may be in contact with the output side surface 124 of the membrane 102 and may provide support to the membrane 102 during filtration. The frame portion 112 may have a lattice-like structure that allows the filtered liquid to pass freely into the backspace 120 inside the filter device 100, while still providing structural support for the polymeric porous filter membrane 102 under fluid pressure caused by the flow of source water through the membrane 102.

[0067] During use, a liquid, such as source water, enters the filter device 100 through the inlet port 106 in the direction indicated by arrow 116 and then fills the headspace 114 within the filter device 100. Sufficient fluid pressure is applied to move the source water through the porous polymeric filter membrane (102) at a desired flow rate. After passing through the filter membrane 102, the source water enters the backspace 120 and then exits the housing 104 through the outlet 108.

[0068] During use in a filtration process, a filter membrane as described, or a composite ("laminated") filter membrane (see below) comprising at least one filter membrane as described, should allow a useful flow rate (volume per time) of a fluid (e.g., source water) through the filter membrane. A useful rate of fluid flow is one that allows for efficient (preferably economically efficient) operation of a filtration system having the filter membrane to supply a required flow (volume per time) of purified water to equipment, such as semiconductor processing equipment.

[0069] Exemplary flow rates for porous membranes as described can range from about 0.1 L / min to about 40 L / min, or more preferably from 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 determined as a function of time and pressure (e.g., liters per m). 2 In terms of the amount of liquid flowing per area of ​​the filter per LMH / h (LMH), it can be expressed 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, etc.

[0070] According to certain exemplary filter membranes as described, the filter membrane may be one layer of a composite membrane (i.e., a "laminated membrane") that includes two or more filter membranes that are effective for removing the same or different contaminants from the source water flowing through the membrane. The composite membrane may include at least one filter membrane made from a base polymer with an amino polyol ligand attached as described. This membrane effectively removes dissolved metal-containing contaminants such as boron (e.g., dissolved metals, metal ions, or metal compounds) as well as contaminants such as silica from the source water flowing through the filter membrane, for example, by a non-sieving filtration mechanism. The second membrane may be different from the first membrane and may be effective for removing other (e.g., non-metallic or non-dissolved metals or metal ions) types of contaminants from the source water, for example, may be effective for removing solid particulate contaminants such as silica (SiO2) particles.

[0071] Porous polymeric filter membranes useful for removing solid particulate contaminants such as silica particles are known and can be in the form (for example) of the polymeric filter membranes described herein that do not require aminopolyol ligands. In general, useful filter membranes can be microporous (e.g., having an average pore size in the range of 10 nanometers to 10 microns) and made from useful polymers such as, but not limited to, polysulfones, polyolefins (e.g., polyethylene), or fluoropolymers (e.g., fluorinated polyolefins). Exemplary membranes can have bubble points in the range of about 10 to 100, e.g., 40 to 60 psi (measured in HFE), and can be effective in removing silica particles by a combination of sieving and non-sieving mechanisms.

[0072] The composite membrane may also contain one or more additional layers that act to maintain the structure of the composite, i.e., one or more support layers. A support layer is a porous membrane or film that is supportively attached to the composite membrane to provide support to the composite membrane, while still allowing source water to flow through the membrane from one side to the other. An exemplary support layer need not perform any filtering function and may have pores or openings that are substantially larger than those of the composite filter membrane, such that the resistance to flow of source water through the support layer is less than the resistance to flow of the composite filter membrane.

[0073] Exemplary support membranes can include macroporous polymer films made from any useful polymer with structure and thickness to add support to the composite. The pores can be openings or fenestrations that are visible without magnification. The polymer can be any polymer that is sufficiently structured and non-chemically reactive (inert), such as polyolefins or modified polyolefin polymers, such as high density polyolefins, polypropylene, perfluoroalkoxyl, and the like.

[0074] 3 shows a schematic diagram of one single example of a composite membrane of the present disclosure. As shown generally, composite membrane 150 includes an upstream face 152, a downstream face 162, an upstream non-filtration support membrane 154, a filter membrane 156, an additional filter membrane 158, and a downstream non-filtration support membrane 160.

[0075] The upstream non-filtering support membrane 154 is a non-filter membrane body that provides physical and structural support for the composite membrane 150. The upstream support membrane 154 is porous and allows the flow of source water through the membrane with relatively low resistance compared to the total resistance to composite flow. The filter membrane 156 is a filter membrane as described, including a porous polymer-based membrane as described with chemically bonded amino polyol ligands. The filter membrane 158 is a membrane adapted to function to filter contaminants, including solid particles such as silica particles. The downstream support membrane 160 is porous and allows the flow of source water through the membrane with relatively low resistance compared to the total resistance to composite flow.

[0076] In use, source water enters the upstream surface 152, passes through an upstream non-filtering support membrane 154, and passes into contact with a filter membrane 156, which comprises a porous polymer-based membrane as described, having aminopolyol ligands chemically bonded thereto. By passing the source water through the filter membrane 156, the membrane 156 is capable of removing dissolved contaminants, such as dissolved metals, from the source water by a non-sieving filtration mechanism. The source water then passes through a filter membrane 158, which is capable of removing particulate contaminants, such as silica particles, from the source water by a sieving filtration mechanism. The source water then passes through a downstream non-filtering support membrane 160.

[0077] In another example shown in FIG. 4, a filter 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 surface of the first porous polymer membrane 202 in direct contact with the input surface of the second porous polymer membrane 222. At least one of the first and second porous polymer membranes 202, 222 has an amino polyol ligand bound thereto as described. The filter 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.

[0078] According to one single example of a useful combination of membranes 202 and 222, filter membrane 222 can be a filter membrane as described that contains a porous polymer-based membrane and an amino polyol ligand. The membrane effectively removes, for example, by a non-sieving filtration mechanism, amounts of dissolved metals, such as boron, metal ions, or metal-containing compounds from the source water flowing through filter membrane 222. Membrane 202 can be a porous polymer membrane that is effective for removing solid particulate contaminants, such as silica (SiO2) particles, that are effective for removing other (non-dissolved metals or metal ions) contaminants from the source water.

[0079] 4, filter device 200 includes a frame having frame portions 210 and 212, where frame portion 210 is in contact with an inner surface of housing 204 attached to portion 212. Portion 212 can contact output surface 224 of membrane 222 and can provide support to membranes 202 and 222 during filtration.

[0080] In an exemplary filtration system, the filter membrane as described or the filter apparatus including the filter membrane as described may be useful in a larger filtration system that further accommodates one or more additional filtration or purification devices that also remove impurities from the source water stream that is filtered through the filter membrane of the present specification (containing the base membrane and the bound amino polyol ligand). The one or more additional filtration or purification devices may include, for example, an ion exchange system, a UV irradiation device, a reverse osmosis device, etc. that removes trace impurities from the source water before or after the source water passes through the filter membrane of the present specification (containing the base membrane and the bound amino polyol ligand).

[0081] Ion exchange resins are known for a variety of specific applications for removing impurities from liquids. These generally include those for industrial water treatment, power generation, pharmaceutical applications, wastewater and recovery, and for use in the preparation of ultrapure water. Examples of ion exchange resins specifically indicated for use in the preparation or processing of ultrapure water include resins made from styrene-based polymers (e.g., polystyrene sulfonate). The ion exchange resins may be of the type referred to as "strongly acidic cation exchange resins," "strongly basic anion exchange resins," or mixed types including both. The ion exchange resins may be in the form of a gel, porous or non-porous, or in the form of solid particles (e.g., beads or pellets). Some ion exchange resins can be regenerated ("regenerable") after a period of use, while others cannot.

[0082] As shown in FIG. 5A, the filtration system 300 includes a filter device 310 including a housing 308 that houses and encapsulates a porous filter membrane 302 as described, which contains a base membrane and bound amino polyol ligand. In some embodiments, a composite membrane, such as the composite membrane 150 described above, can be used as the filter membrane disposed in the filter device 310 shown in FIG. 5A and FIG. 5B. In series with and downstream of the filter device 310 is a filter device 320 that includes an ion exchange resin 322. During operation of the filtration system 300, source water 316 flows into the inlet 306 of the filter device 310 and then passes through the filter membrane 302, where metal-containing contaminants are removed from the source water as the source water passes through the membrane 302. The filtered source water then passes through a conduit 328 into the housing 324 of the filter device 320. The source water passes through, over, or between the solid particles (e.g., beads, pellets) of the ion exchange resin 322 to remove additional amounts of impurities from the source water. Exemplary ion exchange resins may be useful for removing amounts of dissolved metal contaminants such as dissolved iron, titanium, and boron, as well as other metals that may be anionic, cationic, or neutral in charge. After passing through the filter device 320 and the ion exchange resin 322, the source water exits the housing 324 as purified water 340, which may be considered ultra-purified water.

[0083] 5B shows an alternative filtration system 300 that includes filter device 310 and filter device 320 in reverse order. In FIG. 5B, source water passes first through filter device 320, and then through filter device 310.

[0084] The filter membranes of the present disclosure or composite membranes including such filter membranes may be useful for filtering water sources ("source water") that contain relatively low levels of impurities, such as impurities that are already substantially pure or that have been previously processed by a filtration or purification process. In an exemplary method, source water that has been previously processed to remove impurities may be provided, and the source water may be processed using a filter membrane as described to remove a certain amount of remaining impurities, such as dissolved metal impurities, to produce even more purified water (i.e., "purified water" or "ultrapure water"). In particular, porous polymeric filter membranes as described may be useful for removing one or more dissolved and / or suspended metal-containing impurities from the source water that flows through the membrane. Solid particle impurities may be removed from the source water by a sieving or non-sieving mechanism, or both, and dissolved metal impurities may be removed from the source water by a non-sieving mechanism involving binding of the dissolved impurities to the hydroxyl groups of the aminopolyol ligands of the filter membrane. Relatively large metal-containing particles can be captured by the filter due to size limitations depending on the pore size, while metal ions that are otherwise small enough to pass through the pores of the filter membrane are captured by chemical interaction with aminopolyol ligands bound to those immobilized on the membrane surface.

[0085] In certain methods, the filter membranes described, including aminopolyol ligands bound to the base membrane, are used to remove metal contaminants (dissolved metals and metal ions) from source water containing levels of these materials that may be desirably reduced, for example, so that the water can be used in a desired manufacturing process, such as 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, particles of metal compounds (e.g., colloidal silica or solid silica), and may be charged (ionic, e.g., anionic or cationic) or uncharged (non-ionic neutral charge).

[0086] The source water may be water that has previously been processed to remove contaminants, particles, and sediments, for example, as a step to process the water to a desired high or very high level of purity, for processing the water into what is referred to as ultrapure water.

[0087] Ultrapure water is produced by treating a source of stock (non-purified) water, such as river water, ground water, industrial water, etc., with a "pretreatment" process to remove the amount of suspended solids and organic matter in the stock water and produce what is referred to as "primary pure water." Primary pure water may exhibit one or more physical characteristics or impurity levels of ultrapure water (see Table 1 below), but may also benefit from additional treatment to remove some of the residual impurities, such as dissolved metals or dissolved solids, or colloidal silica. Primary pure water may be treated by one or more additional filtration or purification steps to remove very high levels of residual impurities from the water.

[0088] In the subsequent process of preparing ultrapure water, the primary pure water can be treated by one or more of the following processes: ultraviolet irradiation, ion exchange, electrodeionization (EDI), reverse osmosis (RO), degassing, ultrafiltration (using a membrane), etc., to remove trace impurities such as trace ions, organic matter, particulates, dissolved gases, etc. that may be present in the primary pure water.

[0089] The impurity content of ultrapure water can be measured in terms of total organic carbon content (TOC), resistivity and conductivity, total solid particle content, pH, and specificity measurements of certain ions.

[0090] The water source as described herein may be a water source referred to as "primary pure water", which is water that has undergone at least one purification (e.g., filtration) step to prepare ultrapure water. Alternatively, the water source may be a water source that has undergone a first purification step to form "primary pure water" and one or more additional purification steps selected from ultraviolet irradiation, ion exchange, reverse osmosis, ultrafiltration (using membranes), or two or more of these. Such water sources may still contain trace amounts of dissolved metal-containing contaminants, such as dissolved boron, iron, titanium, or silicon, and may contain trace or small amounts of solid particles, such as silica particles. The filter membrane, filter device, or filtration system of the present specification is useful for removing at least a portion of the remaining contaminants.

[0091] The method as described can be effective to produce ultrapure water exhibiting one or more of the following levels of impurities: TIFF2025069178000002.tif104170

[0092] Typically, ultrapure water with individual metal impurity concentrations of 0.01 μg / L or less is used for semiconductor applications, but more recently, even higher levels of purity, such as individual metal impurity concentrations of 1 ng / L or less, are sometimes required.

[0093] In one example, a filter membrane as described may be useful for supplying purified water (e.g., ultrapure water) to a semiconductor or microelectronic device processing system, for example, as rinse water for cleaning or preparing the surface of a microelectronic or semiconductor device substrate during manufacturing.

[0094] FIG. 6 illustrates a semiconductor fabrication system 400 including a chamber 402 in which microelectronic components such as integrated circuits or semiconductor materials are fabricated. The chamber 402 can receive purified water (e.g., ultrapure water) for processing (e.g., cleaning) a microelectronic device or semiconductor substrate housed in the chamber 402. The purified water can be provided from source water contained in and delivered from a source 412 and can be further processed using a filter 435. Movement of the source water through a conduit 416 can be affected by a pump 414. A valve 430 is in fluid communication with the conduit 416 and can regulate the flow of the source water to the filter 435 and subsequently through a conduit 438 to the chamber 402. The filter 435 can include a filter membrane as described herein, including a base membrane having aminopolyol ligands bound to the base membrane. One or more additional filtration or purification devices in series with the filter 435 can be included to remove impurities different from or in addition to the impurities removed by the filter 435. Optional additional filter devices (not shown) may be upstream or downstream of filter 435 and may be one or more of an ion exchange resin, an ultraviolet irradiation device, a reverse osmosis device, and the like.

[0095] During use, source water flows from source 412 through pump 430 and through filter 435 to remove 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 water filtered by filter 435 and the optional ion exchange system may be used in processing steps performed in chamber 402, such as for cleaning surfaces of microelectronic or semiconductor device substrates. EXAMPLES

[0096] Particle Retention Test The filter membranes herein were tested for filtration performance, including particle retention. Particle retention can be evaluated by measuring the number of test particles removed from a fluid stream by a membrane placed in the fluid stream. In one method, particle retention can be measured by passing a test feed 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 of the test feed, collecting the permeate, and measuring the particle content of the permeate. Tests can be performed at a range of levels of particle coverage of the filter (e.g., coverage of 0.05 monolayer, 0.1 monolayer, and 0.2 monolayer, referred to as "filter coverage", i.e., 5 percent filter coverage, 10 percent filter coverage, and 20 percent filter coverage). The concentration of the test particles in the filtrate (or "permeate") can be calculated from the absorbance of the permeate. Particle retention is then calculated based on the concentration of particles in the feedstock ([Feedstock]) relative to the concentration of particles in the filtrate ([Filtrate]) using the following formula: Particle retention rate = ([Feedstock] - [Filtrate]) / [Feedstock] x 100

[0097] Particle retention testing of the filter membranes herein was performed using the SEMI C79 test method (August 2019). Figure 7 is a schematic diagram of the efficacy 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).

[0098] With reference to FIG. 7, testing was performed using the following materials, equipment, and conditions: Flush flow rate: 10 liters per minute (LPM) Flow rate during testing: Based on membrane surface area (11.2 LPM in our test) Particle type: SiO2 Particle size: 6~32nm (polydisperse) Measurement tool: DMA / CPC based LNS 1. Loading filters to target challenge 5E9 particles ≧6 nm DMA = Differential Mobility Analyzer CPC = Condensation Particle Counter LNS = Liquid Nanosizer

[0099] Two filters were tested: Filter 1 (comparative) and Filter 2 (invention).

[0100] Filter 1 was prepared from a polytetrafluoroethylene (PTFE)-based membrane with a non-uniform morphology and was not processed to contain any aminopolyol ligands such as chemically bound quaternary ammonium. Filter 1 properties include bubble point: 30-60 psi, dye binding capacity <0.1 μg / cm 2 Includes:

[0101] Filter 2 is the base membrane of Filter 1 modified to contain a quaternary ammonium bound to the polymer surface. Filter 2 properties include a bubble point of 30-60 psi and a dye binding capacity (DBC) of at least 10 μg / cm 2 Includes:

[0102] The results of the test are shown in Figures 8, 9 and 10.

[0103] As shown in FIG. 8, retention of test particles by comparative filter 1 across the particle size range is well below 100 percent for all diameters, while retention of test particles by filter 2 of the present invention spans a particle size range of 100 percent for all diameters.

[0104] As shown in Figure 9, retention of test particles by Comparative Filter 1 across a range of particle sizes and a range of filter coverage (percent monolayer) ranges well below 100 percent for all diameters and amounts of filter coverage. In comparison, Figure 10 shows that for Filter 2 of the invention, particle retention is 100 percent across the range of filter coverage (percent monolayer) for all particle sizes.

[0105] Static Testing of Boron Removal The membranes herein were tested for their ability to remove boron under static soaking (non-flow) conditions. With this test, a sample of filter membrane is exposed to a known volume of liquid test solution ("additive feed") containing a known amount (concentration) of dissolved boron. The sample filter membrane is contacted with the additive feed (soaked in the additive feed) for a time period that allows boron from the additive feed to be removed from the additive feed by a non-sieving filtration mechanism, for example, by electrostatic or chemical attraction, adsorption, or another type of binding or attraction of boron to the surface of the sample filter membrane. After a time period that allows for non-sieving attraction of boron to the filter membrane, the concentration of boron in the liquid test solution that was in contact with the filter membrane sample is measured. A decrease in the boron concentration in the liquid test solution indicates the amount of boron removed by the sample filter membrane.

[0106] Three sample filter membranes were tested: Tech A (invention), Tech B (comparison, non-invention), and Tech C (comparison, non-invention).

[0107] Tech A membrane was prepared from a base membrane of polyethylene ultra-high molecular weight polyethylene (UPE) with a substantially uniform morphology and an average pore size of 0.2 um, 80 microns thick. The membrane was surface modified with a stable coating of N-methyl-D-glucamine. The amount of N-methyl-D-glucamine modification was quantified by performing a DBC test, which indicates the amount of accessible charged amines on the surface of the membrane. The DBC of Tech A was 120 μg / cm 2 It was determined that.

[0108] Tech B membranes have a substantially uniform morphology and average pore size of 30 nm, a thickness of 25 to 60 microns, and a density of at least 10 μg / cm 2 The PTFE membrane surface was modified with a stable coating of quaternary ammonium with DBC of 1.0.

[0109] Tech C is an ultra-high molecular weight polyethylene membrane modified with sulfonic acid functional groups and had a substantially uniform morphology and an average pore size of 0.2 microns and a thickness of 80 microns. The sulfonic acid functionalized UPE membrane had a pore size of 4.2 meq / m 2 It has an ion exchange capacity of

[0110] The size of the sample filter membrane was a 47 millimeter circular cut-out piece of paper. The volume of the test solution was 25 milliliters. Immersion time of the sample filter membrane in the test solution: 16 hours. ICP-MS was used to measure the boron concentration in the liquid test solution.

[0111] The results are shown in Figure 11. As shown, the filter membrane of the present invention (Tech A) removed essentially all of the dissolved boron, while the comparative filter membranes not of the present invention (Tech B and Tech C) removed only a small portion of the dissolved boron in the test solutions.

[0112] Determination of the dye-binding capacity of positively charged membranes containing bound N-methyl-D-glucamine. This example demonstrates how the degree of positive charge present on a porous membrane can be approximated by measuring the uptake of the negatively charged dye molecule Ponceau S.

[0113] This method is used to measure the amount of charge applied to a surface modified UPE membrane (Tech A). First, a cut piece of paper of known area is placed into a 50 mL conical tube containing 50 mL of diluted (0.005% weight percentage) Ponceau S Red dye (Sigma Aldrich) feed solution in 50% isopropanol, the tube is immediately capped and rotated for 16 hours. After 16 hours of rotation, the cut piece of membrane is removed from the Ponceau S solution. The final "dye binding capacity" (DBC) is calculated by determining the difference in UV absorbance from the original solution compared to the rotated solution, expressed in μg / cm. 2 This number is an approximation of the level of charged functional groups on the surface of the membrane and correlates with the level of membrane ion exchange capacity. In the presence of charged amines due to the presence of bound N-methyl-D-glucamine, the DBC indicates the amount of N-methyl-D-glucamine bound 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-glucamine surface-modified membrane was 120 μg / cm 2 The same method may be useful for determining the DBC of the other membranes of these examples.

[0114] Dynamic testing of boron removal The Tech A membrane was tested for its capacity to remove dissolved metals, including boron, under dynamic conditions. With this test, a sample of the filter membrane (a paper cutout) is held in a stream of liquid test solution ("feed") containing known amounts (concentrations) of dissolved metals, including boron. The test solution is allowed to flow through the sample filter membrane for a set amount of time. See FIG. 12. After a selected amount of time, a sample of the filtrate is taken and the concentration of the dissolved metal in the filtrate is measured. The decrease in the concentration of the dissolved metal in the filtrate relative to the amount of dissolved metal in the test solution indicates the amount of dissolved metal removed by the sample filter membrane.

[0115] With reference to FIG. 13, tests were performed using the following materials, equipment, and conditions: Flow rate: 10mL / min (single pass, monitored and controlled) Film format: φ47mm cut paper strip Test metals and feed concentrations: B: 5 parts per billion (ppb) Ti: 3.6 parts per billion (ppb) (high loading) Fe: 6.4 parts per billion (ppb) (high loading) Fe: 0.68 parts per billion (ppb) (low loading) Ni: 0.13 parts per billion (ppb) (low loading) Cu: 0.13 parts per billion (ppb) (low loading) Sampling Method: Time-based Sampling location: downstream of the membrane Measurement tool: ICP-MS The concentrations of dissolved metals in the test solutions and filtrates were measured using ICP-MS.

[0116] The results for effectiveness in removing dissolved boron are shown in Figure 13. As shown, the filter membrane of the present invention (Tech A) removed essentially the entire amount of dissolved boron at sample times of 5, 10, 15, and 20 minutes.

[0117] Results for effectiveness in removing other dissolved metals at "high load" and "low load" feed concentrations are shown in Figures 14 and 15, respectively. Testing shows that the Tech A filter membrane has the ability to remove significant amounts of these metals from the test solutions at both high and low load conditions (>80% Fe, >95% Ti, >50% Ni, >60% Cu).

[0118] Dynamic testing of boron capacity Using a similar dynamic test setup and test conditions, a Technology A (Tech A) sample filter membrane was tested for an extended single pass period to evaluate the capacity of the Tech A filter membrane to contain boron removed from a test solution. Flow rate: 10mL / min (single pass, monitored and controlled) Film format: 90mm film disc Boron supply concentration: 5 parts per billion (ppb) Sampling Method: Time-based Sampling location: downstream of the membrane Measurement tool: ICP-MS The concentrations of dissolved metals in the test solutions and filtrates were measured and evaluated using ICP-MS.

[0119] The results of the capacity to remove and contain boron from the test solution are shown in Figure 16. The tests show that the Tech A filter membrane is able to remove 100 percent of the boron from the test solution even after 2 micrograms of boron pass through the filter membrane. This is equivalent to approximately 800 micrograms of boron being removed using a 10 inch filter cartridge.

[0120] Having thus described several illustrative embodiments of the present disclosure, one skilled in the art will readily appreciate that still other embodiments may be made and used within the scope of the appended claims. Many advantages of the present disclosure, which are covered by this document, have been set forth in the foregoing description. However, it will be understood that the present disclosure is in many respects merely illustrative. The scope of the present disclosure is, of course, to be defined in the language in which the appended claims are expressed.

Claims

1. a porous polymer-based membrane; an aminopolyol ligand having three or more hydroxyl groups attached to the polymer base membrane; A polymeric filter membrane comprising:

2. The membrane of claim 1, wherein the aminopolyol ligand is N-methyl-D-glucamine.

3. The membrane of claim 1 or 2, wherein the polymer-based membrane comprises polyethylene.

4. 4. The membrane of any one of claims 1 to 3, which is a composite membrane further comprising a porous polymeric filter membrane effective to remove silica particles.

5. 1. A system useful for removing impurities from a source water stream, comprising:

1. A polymeric filter membrane comprising: a porous polymer-based membrane, and Aminopolyol ligands having three or more hydroxyl groups attached to a polymer-based membrane A polymer filter membrane comprising: An ion exchange resin; Flow of source water through polymer filter membrane and ion exchange resin A system comprising:

6. The system of claim 1 , wherein the aminopolyol ligand is N-methyl-D-glucamine.

7. 7. The system of claim 5 or 6, wherein the polymer-based membrane comprises polyethylene.

8. 8. The system of any one of claims 5 to 7, wherein the membrane is a composite membrane further comprising a porous polymeric filter membrane effective to remove silica particles.

9. 9. The system of any one of claims 5 to 8, wherein the source water flow is configured to first pass through an ion exchange resin and then through a polymeric filter membrane.

10. 9. The system of claim 5, wherein the source water flow is configured to first pass through a polymeric filter membrane and then through an ion exchange resin.

11. The source water, Resistivity: >18.18MΩ・cm, Total organic carbon: <1 μg / L, Online dissolved oxygen: <10 μg / L, and Bacteria: <1CFU / 100mL The system according to claim 5 , wherein the primary pure water exhibits one or more of the following characteristics:

12. 12. The system of any one of claims 5 to 11, wherein the source water stream after passing through the polymeric filter membrane and the ion exchange resin has an individual metal impurity concentration of 0.1 μg / L or less.

13. 13. The system of any one of claims 5 to 12, wherein the source water stream after passing through the polymeric filter membrane and the ion exchange resin has a boron concentration of 0.1 μg / L or less.

14. 1. A method for removing impurities from a source water stream, comprising: a porous polymer-based membrane; an aminopolyol ligand having three or more hydroxyl groups attached to the polymer base membrane; The method includes flowing source water through a polymeric filter membrane comprising:

15. The method of claim 14, wherein the aminopolyol ligand is N-methyl-D-glucamine.

16. 16. The method of claim 14 or 15, wherein the polymer-based membrane comprises polyethylene.

17. 17. The method of any one of claims 14 to 16, comprising passing the source water stream through an ion exchange resin before or after passing the source water stream through a polymeric filter membrane.

18. The source water, Resistivity: >18.18MΩ・cm, Total organic carbon: <1 μg / L, Online dissolved oxygen: <10 μg / L, and Bacteria: <1CFU / 100mL 18. The method according to claim 14, wherein the primary pure water exhibits one or more of the following characteristics:

19. 19. The method of any one of claims 14 to 18, wherein the source water is water that has previously been processed by ion exchange resins, ultraviolet irradiation, ultrafiltration, or a combination of two or more of these.

20. 20. The method of any one of claims 14 to 19, wherein the impurity is a dissolved metal or silica.

21. 21. The method of any one of claims 14 to 20, wherein the impurity is boron.

22. 22. The method of any one of claims 14 to 21, comprising removing silica particles from the source water by passing the source water through a second porous polymeric filter membrane effective to remove silica particles, either before or after passing the source water through the polymeric filter membrane.

23. 23. The method of any one of claims 12 to 22, producing ultrapure water.

24. 24. The method of any one of claims 12 to 23, producing water having an individual metal impurity concentration of 0.1 μg / L or less.

25. 25. The method of any one of claims 12 to 24, producing water having a boron concentration of 0.1 μg / L or less.

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