HK1140181A - System and method of slurry treatment - Google Patents

Description

Slurry treatment system and method

Background

1. Field of the invention

The present invention relates to a system and method for reducing the concentration of one or more metal species in a waste stream, and more particularly, to a system and apparatus for removing one or more metal species from a chemical mechanical planarization waste slurry stream.

2. Discussion of the related Art

Various techniques can be used to reduce the concentration of one or more target species in the stream. For example, Medford et al, in U.S. Pat. No. 3,301,542, disclose a system for treating acidic etching solutions. Swanson et al, in U.S. Pat. No. 3,428,449, disclose the use of phenolic oximes to extract copper from acidic solutions. Spinney, in U.S. patent 3,440,036, discloses the recovery of copper from copper-containing solutions. Stephens, in U.S. patent 3,912,801, discloses the solvent extraction of metals using cyclic alkylene carbonates. Koehler et al in U.S. patent 3,914,374 disclose the removal of residual copper from a nickel solution. Asano et al, in U.S. patent 3,923,741, disclose a process for the extraction of aqueous acrylamide solutions. Asano et al also disclose in us patent 3,941,837 a method of treating an aqueous solution of acrylamide. Leach et al, in U.S. patent 4,010,099, disclose a settler for copper liquid extraction systems. Etzel et al, in U.S. patent 4,210,530, disclose the use of unexpanded vermiculite cation exchange columns to treat metal plating waste. Dalton, in U.S. patent 4,231,888, discloses a composition for extracting copper from aqueous copper salts. Merchant et al, in U.S. patent 4,239,210, disclose a method for regenerating etchants and recovering etched metals. Brown et al, in U.S. Pat. No. 4,666,683, discloses a method for removing copper from a solution of a chelating agent and copper. Gefvart, in U.S. patent No. 5,256,187, discloses the separation of noble metals by ion exchange methods. Guess, in U.S. patent 5,298,168, discloses the ferrous dithionite process and compositions for removing dissolved heavy metals from water. Siefert et al, in U.S. Pat. No. 5,346,627, disclose a method for removing metals from a fluid stream. Marquis et al, in us patent 5,348,712, disclose the use of carbonates in metal ion extraction. Hayden, in U.S. Pat. No. 5,464,605, discloses a method for decomposing and removing peroxides. Abe et al, in U.S. patent 5,476,883, disclose a process for preparing acrylamide from purified acrylonitrile. Misra et al, in U.S. Pat. No. 5,599,515, disclose a method for removing mercury from a solution. The removal of metal ions from wastewater is disclosed in U.S. patent 6,315,906 to sasseaman et al. Filson et al, in U.S. Pat. No. 6,346,195, disclose the ion exchange removal of metals from wastewater. Ion exchange removal of metal ions from wastewater is similarly disclosed by Kemp et al in U.S. patent 6,818,129. However, Kemp et al in U.S. patent 6,818,129 indicate that hydrogen peroxide, if present, cannot be present with certain resins due to its incompatibility. Kemp et al also indicate that ion exchange can be used to attach copper ions, but cannot be used in the polishing slurry stream due to the presence of solids in the polishing slurry stream, typically in the form of silica, alumina slurry.

Summary of The Invention

In accordance with one or more embodiments, the present invention is directed to a method of treating a slurry stream. The method can include providing a slurry stream comprising at least one metal and at least one oxidizing agent at a concentration of at least about 50mg/l, and introducing the slurry stream into an ion exchange column.

In accordance with one or more embodiments, the present invention is directed to a method of treating a chemical mechanical polishing slurry stream. The method can include introducing the slurry stream into a treatment system consisting essentially of at least one ion exchange unit comprising a chelating ion exchange resin.

According to other embodiments, the present invention relates to a method of manufacturing an electronic component. The method can include chemically-mechanically polishing the electronic component with a slurry, introducing at least a portion of the slurry into a processing system consisting essentially of an ion exchange column comprising an ion exchange material containing iminodiacetic acid functional groups.

In accordance with one or more embodiments, the present invention is directed to a treatment system for treating a slurry stream that may include at least one metal selected from the group consisting of copper, lead, nickel, zinc, cobalt, cadmium, iron, manganese, and tungsten, and at least one oxidizing agent selected from the group consisting of nitric acid, hydrogen peroxide, ferric nitrate, and ammonium persulfate at a concentration of at least about 50 mg/l. The treatment system may include an inlet in fluid communication with a source of the slurry stream and a device to reduce the concentration of the at least one metal from the slurry stream.

In accordance with one or more embodiments, the present invention is directed to a method for facilitating the treatment of a slurry stream containing at least one metal species. The method includes providing a treatment system consisting essentially of an ion exchange column containing ion exchange media. The ion exchange media comprises at least one pendant functional group capable of forming a complex with the at least one metal species.

Brief description of the drawings

The figures are not drawn to scale. In the drawings, each identical or nearly identical element (element) is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In each figure:

FIG. 1 schematically illustrates a treatment system according to one or more embodiments of the invention;

FIG. 2 schematically illustrates a treatment system according to one or more embodiments of the present invention as described in examples 1 and 2;

FIG. 3 schematically illustrates the treatment system described in examples 3 and 4;

FIG. 4 schematically illustrates yet another treatment system described in example 5; and

FIG. 5 schematically illustrates the pretreatment system described in example 6.

Detailed Description

The invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "containing," "involving," and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

In accordance with one or more embodiments, the present invention provides systems and techniques for removing metal ions or at least reducing the concentration of metal ions from a solution or stream. In certain instances, the methods and systems of the present invention can be used to remove one or more undesirable species (e.g., metal ions) from one or more fluid streams (typically, one or more wastewater streams). According to other embodiments, the present invention provides systems and techniques for removing or at least reducing the concentration of one or more transition metal ions from a solution and/or stream (e.g., a slurry stream) containing a high content of suspended solids (also referred to herein as particulates). In certain instances, the present invention provides systems and techniques for removing or at least reducing the concentration of copper ions from one or more slurry streams. For example, the methods and systems of the present invention can remove copper ions from wastewater from polishing slurry byproducts of Chemical Mechanical Polishing (CMP) integrated circuits, attach metal ions, and form environmentally clean water discharge products. The phrase "environmentally clean" means that the wastewater stream may be discharged to a municipal wastewater treatment plant, so that the wastewater discharge stream contains copper ions at a concentration of less than about 0.5mg/l (about 0.5 ppm). According to other embodiments, the treatment systems and techniques of the present invention may include, consist essentially of, or consist of one or more ion exchange unit operations that may remove one or more target species from one or more slurry streams and may render the one or more slurry streams suitable for discharge to the environment. As used herein, the phrase "suitable for discharge" means that the concentration level of one or more regulated substances contained in the treated stream is not greater than the limits of governmental restrictions. Thus, the systems and techniques of the present invention may be used to facilitate the manufacture of one or more semiconductor devices and/or one or more types of semiconductor devices by delivering a dischargeable slurry stream that meets or exceeds one or more imposed regulatory limits. In accordance with one or more embodiments, the present systems and techniques may remove or at least reduce the concentration of one or more target metal species to an amount or concentration that meets environmental emission limits and/or guidelines. In accordance with certain aspects of one or more embodiments of the present invention, the disclosed systems and techniques may include one or more treatment systems comprising, in some cases consisting essentially of, one or more unit operations that contact a slurry stream and remove one or more target species therefrom.

The systems and techniques of the present invention may also be used to reduce the concentration of contaminants (such as, but not limited to, transition metals) from one or more streams containing entrained particulate matter. The total solids dried at 103-105 ℃ using Standard Methods 2540B (1998, 20 th edition) are used herein to define solids or particulates.

The systems and techniques of the present invention may be used to remove metal species from wastewater streams. In accordance with one or more embodiments, the present systems and techniques remove metal ions (e.g., but not limited to, copper metal ions) from a wastewater stream (e.g., a byproduct polishing slurry stream from one or more chemical mechanical planarization processes) during a manufacturing process involving integrated circuit microchip devices.

Semiconductor manufacturing processes typically use one or more metals (such as, but not limited to, aluminum) and/or transition metals (such as copper and tungsten) during one or more of the manufacturing operations of a microchip device or component. Chemical mechanical planarization or polishing (CMP) is one technique that may be utilized during the manufacturing operations of such devices. CMP operations may be used to produce smooth surfaces on such semiconductor devices. Typical CMP processes use one or more polishing slurries to facilitate the planarization process. Polishing slurries are commonly used with polishing pads to remove excess or undesirable metal materials from semiconductor devices. To further or facilitate the planarization process, the polishing slurry typically comprises one or more abrasives, and in some cases, one or more agents that facilitate the planarization process.

During CMP, silicon and other metals are typically removed from the semiconductor device and carried in a chemical mechanical polishing slurry stream. More specifically, CMP planarization operations performed on copper-based microchip devices can produce a byproduct "lapping" (polishing) slurry wastewater stream that typically contains a metal species (typically in ionic form) at a concentration of from about 1mg/l to about 100 mg/l. Typical CMP equipment can produce a chemical mechanical slurry stream, typically including a rinse stream, at a flow rate of about 10 gpm. However, since manufacturing facilities typically operate a plurality of these devices, a sufficient amount of one or more metallic copper may be present in the aggregate slurry stream at a concentration, amount, or bulk that, if left untreated, may pose an environmental concern. For example, multiple copper CMP tool sets (tool cluster) may produce about 100gpm of wastewater.

The stream to be treated may comprise one or more oxidants which are additives. The oxidizing agent can be any substance that promotes the dissolution of a metal species, such as copper. For example, the oxidizing agent can be nitric acid, hydrogen peroxide (H)₂O₂) Iron nitrate and ammonium persulfate and mixtures or combinations thereof. Other non-limiting examples of oxidizing agents or precursors thereof are iodates, periodates, bromates, perbromates, chlorates, perchlorates, peroxides, nitrate compounds, persulfate compounds, permanganate compounds, and chromate compounds. The concentration of the oxidizing agent in the slurry stream may be sufficient to promote metal dissolution, for example, to promote transition metal dissolution. For example, the concentration of the one or more oxidizing agents may be at least about 50mg/l, and typically from about 50mg/l to about 1,000 mg/l.

One or more chelating agents (e.g., citric acid or ammonia) may also be present in the byproduct slurry stream to be treated to facilitate maintaining one or more transition metals therein in solution. The slurry waste water stream may also contain solids or particulates, typically in the size range of about 0.001 to about 1 μm, in an amount or concentration of about 500 to about 5,000mg/l (about 500 to about 5,000 ppm). Complexing agents (e.g., gluconate, tartrate, citric acid, and ammonium hydroxide) that promote etching or increase the corrosion rate of transition metals (e.g., copper) may also be present in the CMP slurry stream. Table 1 lists common CMP slurry stream components and their typical concentrations.

Notably, ion exchange media suppliers and equipment manufacturers encourage the removal of particulate matter in advance (i.e., upstream of the ion exchange system) and emphasize that the removal of solids is an essential aspect of the pretreatment system since the particles can bind and block the ion exchange media and work as a granular filter. Thus, if the particles are not removed, the suspended solids aggregate, resulting in an increased pressure drop across the resin bed. The increased pressure drop further typically results in channeling phenomena in which the fluid stream to be treated is directed to the least resistant flow path, rendering at least a portion of the resin bed ineffective, limiting resin contact with the processing fluid. This results in significant contaminant discharge and poor bed capacity. Suspended solids and colloidal materials may also coat ion exchange media to reduce the rate of diffusion of ionic species out of and out of the media. Ion exchange media manufacturers also prohibit (script) pretreatment of the stream to be treated to remove or neutralize soluble components that degrade the ion exchange media. Examples of such substances are oxygen, ozone, chlorine, hydrogen peroxide and other oxidizing agents or oxidizing substances or agents. Thus, prior art systems that use ion exchange media include one or more pretreatment unit operations to remove such particulate and/or oxidizing species. The systems and techniques of the present invention, in turn, inventively eliminate or reduce the reliance on such additional complex equipment in the treatment of particulate streams that may contain one or more oxidizing species.

TABLE 1 common CMP slurry compositions

Components	Concentration of
		Dissolved copper	5-100mg/l
Total solids	500-5,000mg/l
		Oxidizing agent	50-1,000mg/l
Etching agent	200mg/l
		Complexing agents	10-400mg/l
Deionized water background (for the most part)	99％+
		pH	6-7

According to one or more aspects, the ion exchange media used in the systems and techniques of the present invention comprises, consists essentially of, or consists of one or more materials that can form or facilitate the formation of one or more chelator complexes with one or more target species. For example, the ion exchange media can comprise one or more functional groups that can form one or more ligands or complexes with one or more metal species. Thus, according to certain aspects of the invention, the ion exchange medium comprises one or more ligands or chelating moieties, typically as pendant groups on the substrate (substrate). The one or more functional groups may have any suitable functionality that can bind or immobilize one or more target species, thereby removing or at least reducing the concentration of the target species from the fluid carrying the target species or the fluid to be treated. Thus, during the treatment operation, one or more target species may be bound or immobilized to the ion exchange media material via one or more functional groups. The one or more pendant groups may be supported on a polymer or other support medium comprising the ion exchange media material. Thus, the ion exchange media can comprise a first region having a first functional group and a second region having a second functional group. Further, the ion exchange media can comprise any number or type of such functional groups at various concentrations or densities to provide the desired loading capacity. Thus, generally on a volume basis, for example, an ion exchange medium can have a first region comprising a first density or concentration of functional groups and one or more second regions comprising a second or other density or concentration of second functional groups. The first and second regions may differ in one or more aspects to provide flexibility in capturing one or more target species, but may comprise the same functional groups.

In accordance with one or more embodiments, the present systems and techniques may provide a method for removing or at least reducing the concentration of copper ions. The method comprises contacting a stream comprising copper ions with a treatment system comprising, consisting essentially of, or consisting of an ion exchange bed comprising a complexing ion exchange media, preferably without prior removal of solids or particulates and/or prior removal or reduction of an oxidizing agent by catalytic exposure to carbon. Contacting the stream can include introducing the stream into the one or more ion exchange beds in a downward flow direction or an upward flow direction.

In other cases, the invention relates to pretreatment systems that do not add chemicals. For example, the pretreatment system can neutralize, remove, or at least reduce the concentration of oxidizing agents that may be present in the stream to be treated. For example, the pretreatment system may introduce energy to facilitate reducing the oxidizing agent. Non-limiting examples of such pretreatment systems include, but are not limited to, electrochemical, photochemical and thermochemical techniques.

For example, electrochemical techniques may use one or more electrochemical cells comprising an anode and a cathode (electrodes) connected to an externally supplied power source to introduce electrical current into a liquid. The cell may be constructed as a batch tank, a fluid passing through a tube, or other structure in which a solution containing an oxidant is electrically connected to the electrodes. With this arrangement, electrons lost by one or more electrodes are transferred to other electrodes through external connections. Thus, a reduction reaction may occur at the cathode and an oxidation reaction may correspondingly occur at the anode. The current supplied (e.g., direct current) is typically controlled by a rectifier. The amount of current (amperage) used may depend on a number of factors or conditions, such as the solution characteristics and/or concentration and type of chemical species involved and the rate at which the concentration is being reduced or is desired.

Photochemical techniques generally provide actinic radiation that promotes one or more reactions. For example, photochemical techniques may use ultraviolet radiation to promote one or more reduction reactions.

Thermochemical techniques can include heating a solution comprising an oxidizing agent to a temperature that promotes decomposition of the oxidizing species. For example, for copper CMP slurry wastewater, the temperature may be up to the boiling point of water (including that temperature) (about 100 ℃). The rate of reaction (including reduction or decomposition reactions) is generally increased at high temperatures, thus promoting destruction of one or more oxidizing species.

The complexing ion exchange media typically comprises at least one complexing or chelating functional group. The functional group includes any group that forms a complex with the target species, typically a multidentate group. For example, the ion exchange media can comprise iminodiacetic acid functional groups on the polymer backbone. Other functional groups that may be used in one or more embodiments of the present invention include, but are not limited to, polyamine, bis (picolylamine), and aminophosphonic acid groups. The choice of functional group may depend on a number of factors, such as affinity for the target species. Thus, for example, the selection of the functional group or groups used may depend on the metal species of interest, e.g., a transition metal which may be any one or more of copper, lead, nickel, zinc, cobalt, cadmium, iron, tantalum, silver, gold, platinum, palladium, iridium, rhodium, ruthenium, manganese, tungsten, and hafnium and/or gallium.

As exemplarily shown in fig. 1, one or more collection tanks 30 may be used to collect one or more streams to be treated from one or more CMP systems 20 for subsequent processing in a treatment system 40. Optionally, an acid or base (not shown) may be introduced to adjust the pH of the stream to be treated.

In some cases, the treatment system may include two or more ion beds arranged in parallel or in series or a combination thereof. For example, the treatment system may comprise two trains (train) each comprising a first ion exchange bed and a second ion exchange bed downstream of the first bed. The first ion exchange bed may be considered the main bed, typically removing or reducing the concentration of the target metal species in the slurry stream, and the second ion exchange bed downstream may be considered the polishing bed (refining bed) removing any residual target species. The primary and polishing beds are interchangeable if desired. The primary bed may be replaced, for example, after a predetermined time or when an unacceptable condition or concentration of one or more target species in the outlet stream is detected. The polishing bed can be placed in the main bed position and the nascent column can be placed in the polishing bed position. The spent ion bed may be reprocessed and/or regenerated.

Typically the ion exchange media comprises pendant chelating functional groups on the crosslinked polymer backbone. The support substrate (supporting support) or backbone of most ion exchange resins is typically composed of long chains of polystyrene. Resin manufacturers typically improve strength, making the resin insoluble in water and/or non-aqueous solvents, and polystyrene chains are typically reacted with a crosslinking agent such as divinyl benzene (DVB). Typically, the reaction links multiple chains of polystyrene together through one or more linkages. The oxidizing agent attacks and destroys not only the pendant functional groups on the resin, but also the DVB linkages. All oxidants attack the functional groups and DVB cross-linking. As more and more DVB cross-linking is broken, the resin absorbs water and swells and becomes soft. In use, the softened resin expands and presses together, preventing or impeding fluid flow therethrough. Some oxidizing species are more aggressive than others and higher concentrations of oxidizing agents accelerate the rate of degradation. Other conditions, such as low or high pH, heat, and the presence of a catalyst also accelerate the rate of degradation. In some cases, transition metals (e.g., copper) can catalyze oxidative degradation of the resin, particularly under acidic conditions. Typically, the chelating ion exchange media can have a working capacity (operating capacity) of about 1.5 to 2.0 pounds or more of metal per cubic foot.

Typically, the ion exchange media has a maximum uniformity coefficient of about 1.7. The ion exchange resin of the process and apparatus of the invention is sized to control bead size. The ion exchange resin of the process and apparatus of the present invention may have the following general properties.

As described above, the treated slurry stream exits the treatment system in a state suitable for discharge. The optionally treated stream may be further processed in one or more post-treatment systems (not shown). For example, solids may be removed in one or more filtration unit operations or systems. One or more agents (e.g., coagulants and/or flocculants) may be used to improve one or more post-treatment processes. Examples of other unit operations that may be used in the aftertreatment system include, but are not limited to, reverse osmosis processes and other systems and techniques that may further reduce other target species from the stream.

TABLE 2 general Properties of ion exchange resins

Characteristics of	Value of
		Minimum bead size 90%	0.4-1.23mm
Effective size	0.55mm
		Coefficient of uniformity	1.7
Bulk weight(+/-5％)	800g/l
		Density of	1.18g/ml
Water retention rate	50-55% by weight
		pH range	0-14
Functional group	Iminodiacetic acid
		Structure of the product	Macropore
Substrate	Crosslinked polystyrene
		Minimum Capacity (Minimum Capacity)	2.2eq/l，H+Form(s) of

Regeneration of the supported (typically saturated) ion exchange media can be achieved by removing the complexed metal species therefrom using one or more mineral acids (e.g., sulfuric acid). However, in some cases, it is preferred to use hydrochloric acid.

Examples

The function and advantages of these and other embodiments of the present invention will be further understood from the following examples, which illustrate the benefits and/or advantages of one or more of the systems and techniques of this invention, but do not illustrate the full scope of the invention.

In each example, copper in solution was measured according to standard method 3120B, and metals were measured by Inductively Coupled Plasma (ICP) method or 3125B, inductively coupled plasma/mass spectrometry (ICP/MS) method (1998, 20 th edition).

Solids content was determined according to U.S. EPA method 160.3.

The hydrogen peroxide concentration was determined by direct titration with a standard potassium permanganate reagent.

The ion exchange resin used was LEWATITTP207, a weakly acidic macroporous ion exchange resin containing chelating iminodiacetic acid, available from Sybron Chemicals Inc., a LANXESS Company, Birmingham, N.J..

EXAMPLE 1 Performance of ion exchange resin exposed to oxidizing agent

In this example, a treatment system of one or more embodiments of the present invention comprising an ion exchange column using a chelating ion exchange resin is exposed to an oxidizing agent. The effective capacity of the exposed ion exchange resin is used to characterize the deterioration and impact on its performance.

The treatment system is schematically shown in FIG. 2. The system consists essentially of an ion exchange column 210 containing ion exchange resin. A pump 212 is used to draw the copper-containing solution from a source or feed tank 212 and into the ion exchange column 210. The treated fluid from the ion exchange column 210 is collected with an effluent holding tank 216. The solution is not recycled such that the ion exchange material is exposed to a solution having the same initial and final copper concentrations. Prior to the first run, the resin was pre-conditioned by absorbing water in deionized water for at least 24 hours, and then completely converted to the acid form by exposure to an approximately 10% hydrochloric acid solution.

The resin bed of the ion exchange column was about 1.5cm in diameter and about 16cm thick.

Multiple runs were performed by exposing the resin bed to various oxidant-containing solutions. The solution also contained about 40mg/l of copper species in the form of sulfate. The exposure was performed as follows: each solution was passed through the ion exchange column for about 8 hours per day, followed by a stationary non-flowing state for about 16 hours. The pH of the solution was adjusted to about 3 by adding sufficient sulfuric acid.

The oxidizing agent used was hydrogen peroxide at various concentration levels as described in table 3. Table 3 also lists the ion exchange bed capacity measured after various time intervals of exposure during the exposure. Bed capacity was normalized to unexposed resin. More specifically, the capacity of the ion exchange resin not exposed to the oxidizing agent was designated as 1.0, and the capacity of the resin after exposure was designated relative to the unexposed capacity. Thus, for example, if the capacity of the ion exchange resin exposed to the oxidant is measured to be about half that of the unexposed resin, the capacity is designated as about 0.5. Resin capacity can be determined by relative saturation. For example, by regeneration using about 10% hydrochloric acid solution, whereby the metal can be removed from the resin. About 2 liters of copper sulfate solution containing about 3,000mg Cu/l was passed through about 25ml of resin to completely deplete the ion resin exchange sites of copper species. Excess copper solution is washed from the resin. The resin was copper-depleted with about 0.5 liters of about 10% hydrochloric acid solution. The desorbed solution (strip solution) was collected and analyzed for total copper content. The amount of copper measured is directly related to the number of available exchange sites per unit volume of ion exchange resin (the value for the unused resin is designated as 1.0). Exposure to oxidizing species or agents renders some exchange sites unusable, and thus the amount of copper that can be loaded per unit volume of resin decreases with degradation. Thus, the value of the resin exposed to the oxidizing agent is less than 1.0 compared to the virgin resin.

The data in table 3 show the decrease in ion exchange resin capacity after prolonged exposure. In addition, the rate of degradation accelerates at higher oxidant concentrations.

TABLE 3 Effect of oxidant exposure on Iminodiacetic acid resins

EXAMPLE 2 Performance of ion exchange resin when oxidizing agent is chemically neutralized

In this example, metal treatment capacity was evaluated using a treatment system including an ion exchange column according to one or more embodiments of the present invention, and the oxidizing agent was chemically neutralized. The treatment system is schematically illustrated in fig. 2 and is substantially as described in example 1. The neutralizing agent or reducing agent is sodium pyrosulfite. However, other reducing agents (e.g., sodium bisulfite and sodium sulfite) may be used. Neutralization of hydrogen peroxide with sodium sulfite, sodium bisulfite or sodium metabisulfite results in the formation of sodium sulfate (Na)₂SO₄). The initial concentration of hydrogen peroxide in the solution to be treated prior to neutralization is listed in table 4. Table 4 also lists the concentration of the sodium sulfate product formed. For each test, the initial concentration of the metallic species copper (sulfate) in the solution was about 40 mg/l. The initial pH of each solution was about 3.

The resin bed of the ion exchange column was about 1.5cm in diameter and about 16cm thick.

Citric acid is commonly used in copper CMP slurry formulations as an organic chelating agent for copper. Citric acid typically complexes with copper ions generated during copper CMP, thereby inhibiting the precipitation and/or re-adsorption (re-adsorption) of these species on the semiconductor surface. The organic chelating agent binds copper to varying degrees. Generally, the stronger the chelating agent is bound to the copper, the more difficult it is for the ion exchange resin to remove the copper from the chelating agent and bind it to the ion exchange resin. The high salt background also weakens the adsorption of copper from solution by the resin due to the high ionic background. When a chemical reducing agent (e.g., sodium bisulfite) is used to chemically decompose an oxidizing agent (e.g., hydrogen peroxide), the resulting chemical reaction increases the overall ionic background in the solution. More specifically, the reaction between sodium bisulfite and peroxide can produce sodium and sulfate ions in solution. The higher the oxidant concentration, the more bisulfite is required to neutralize and, therefore, the higher the resulting ionic background.

Table 4 lists the number of equivalent Bed Volumes (BV) passed through the resin bed before the effluent concentration was about 30mg/l (designated as the breakthrough condition), i.e., before the influent metal concentration was about 75%. Table 4 compares the copper loading of the ion exchange for the three cases. The "blank" or baseline case refers to copper loading when no chelating agent (e.g., citric acid) is present and there is only a small background loading of ions. The "citric acid" condition refers to the copper loading when an amount of the chelating agent, citric acid, is added to the baseline condition at levels typically present in copper CMP wastewater. In this case, the ionic background is hardly increased since citric acid is only partially ionized in the solution. The "sulfate" case represents the copper loading when the ionic background is significantly increased in the absence of citric acid. The amount of sodium sulfate salt is equal to the amount formed if about 1,100ppm of hydrogen peroxide is removed by sodium bisulfite (in the other two cases, the amount is equal to the amount formed if about 200ppm of peroxide is removed). The results show that the citric acid and sulfate cases are essentially the same as the baseline case, and that the use of a chemical reducing agent to increase the background ion load has no significant negative effect on the removal of copper by the ion exchange resin, regardless of the presence or absence of citric acid.

TABLE 4 Effect of Exposure on high sulfate levels

BTA is 1, 2, 3-benzotriazole. BTA is the "alkyl/aryl triazole rust inhibitor (anti-tarnish)" component typically found in copper CMP slurry formulations. BTA generally prevents the formation of copper oxide on the polished copper left on the semiconductor device during and after the CMP process.

Example 3 high Total solids flow

This example illustrates the performance of the treatment system of one or more embodiments of the present invention in treating a slurry stream from a CMP process. Evaluation was performed for about 20 days. The test also shows that the resin is still effectively absorbing copper even in the presence of the oxidizing agent.

The system schematically shown in fig. 3 comprises a carbon column 311 and downstream thereof an ion exchange column 310. The CMP solution is pumped from feed tank 314 through carbon column 311 and ion exchange column 310 using pump 312. Sample point 316 is located between carbon column 311 and ion exchange column 310. The treated fluid from the ion exchange column 310 is collected in a collection tank 318.

The system was run for about 8-12 hours per day, closed at the end of each day, and restarted the next day. After 12 days, the ion exchange test was stopped and the removal of hydrogen peroxide with carbon was continued for an additional 8 days. The slurry solution flowed uniformly and stably through the carbon and ion exchange cells throughout the test, which indicated that there was no solids accumulation on each media. Examination of the media at the end of the test showed no slurry solids build up in each media.

Preparing a copper CMP slurry wastewater simulant. Aliquots of the industrially produced copper CMP slurry concentrate were diluted to the total solids test conditions. The slurry solution was prepared by diluting commercially available copper CMP slurry followed by the addition of hydrogen peroxide and copper sulfate to simulate copper CMP slurry wastewater. Calculated amount of copper sulfate (technical grade CuSO)₄·5H₂O crystals from Chem One Ltd., Houston, Texas) and peroxideHydrogen (about 30% H)₂O₂Electronic grade, available from ashland specialty Chemical, Dublin, Ohio) was added to the influent slurry solution. The hydrogen peroxide concentration of the slurry stream entering and exiting the ion exchange resin bed on a daily basis is as follows. Likewise, the feed and exit copper concentrations and the solid feed concentrations are listed accordingly. The pH was adjusted to about 3 by adding sulfuric acid. The particle size of the solid is from about 0.001 μm to about 1 μm.

The resin bed of ion exchange column 310 was about 8 inches in diameter and about 40 inches thick. The carbon column 311 is about 14 inches in diameter and about 40 inches thick. The carbon used is CENTAURGranular activated Carbon, available from Calgon Carbon Company, Pittsburgh, Pennsylvania.

Samples were taken and analyzed after the hours listed in table 5. The data in Table 5 show that copper can be removed even at total solids loadings as high as about 4,500 mg/l. Further, from the results of the experiments on day 4, day 5 and day 7, copper was effectively removed without removing hydrogen peroxide. The total solids in the tests of table 5 were derived primarily from the slurry particulate solids themselves, i.e., silica and alumina for grinding and polishing. Very little solids come from dissolved ions (e.g., copper and sulfate ions).

TABLE 5 Effect of high Total solids

Example 4 removal of hydrogen peroxide using carbon and filter media

In this embodiment, the slurry effluent from the CMP process is processed in a processing system comprising a pre-processing subsystem. The treatment system, substantially as shown in FIG. 3, comprises a pretreatment system 311 that is a carbon column or a filter media column and an ion exchange column 310. A pump 312 is used to introduce a solution containing solids, oxidant and copper from a feed tank 314. The treated slurry is collected and sampled in a collection tank 318.

Using a composition containing CENTAURGranular activated Carbon (available from Calgon Carbon, Company, Pittsburgh, Pennsylvania) or BIRMA pretreatment system for particulate filter media (available from Clack Corporation, Windsor, Wisconsin) removes and/or neutralizes hydrogen peroxide in the slurry stream. CENTAURThe granular activated carbon system consisted primarily of columns about 8 inches in diameter and about 40 inches thick. BIRMThe granular filter media subsystem consisted essentially of a column about 8 inches in diameter and about 20 inches thick. For each experiment, the corresponding ion exchange column was approximately the same size as the corresponding carbon or filter media column.

The copper, total solids (copper solids) and hydrogen peroxide concentrations in the slurry stream after feeding and treatment are listed in tables 6 and 7. The data indicate that the pretreatment system can reduce or remove hydrogen peroxide concentration and effectively remove copper species through the ion exchange column.

TABLE 6 removal of oxidants with granular activated carbon

TABLE 7 removal of oxidants with granular Filter media

(NA not analyzed)

P22 formula 4

Example 5 ion exchange Properties to Change Total solids and Hydrogen peroxide concentration

As shown schematically in fig. 4, the removal of oxidants and metals by a pretreatment subsystem comprising a carbon bed and a treatment system comprising two ion exchange beds was evaluated using slurry wastewater from an industrial copper CMP process. Carbon bed 510 is comprised of approximately 3.6 cubic feet of CENTAURGranular activated carbon, ion beds 512 and 514 each consisting of about 3.6 cubic feet of LEWATIT containing chelating iminodiacetic acid groupsTP207 weakly acidic macroporous ion exchange resin. Slurry fluid is introduced into the system from feed tank 516 by pump 518. The raw copper-containing slurry provided, about 30% hydrogen peroxide (from Ashland Specialty Chemical) and copper sulfate pentahydrate (from Chem One Ltd) were used to adjust the total solids, hydrogen peroxide and copper concentrations to the values shown in table 8. The pH was adjusted to the level shown in Table 8 by the addition of about 25% sulfuric acid solution and diluted with deionized water at a ratio of about 1: 1. The treated streams from the ion exchange columns 512 and 514 are collected in a collection tank 520.

Samples were taken at sample point 522 and collection tank 520 for analysis. Table 8 lists the properties of the feed and slurry fluids for each test. The data show that copper can be effectively removed even without the removal of hydrogen peroxide by the activated carbon subsystem as shown in the runs nos. 2, 4,5 and 10. The data also shows that treatment can be achieved even for slurry streams with solids up to about 20,000 ppm.

TABLE 8 removal of hydrogen peroxide and copper

Test number	pH	Flow rate (gpm)	Total solids (mg/l)	Copper (mg/l)	H2O2(mg/l)	Copper removal (%)	H2O2Removal of (2) (%)
								1	3	3.5	12,795	54.9	64.6	99.6	100
2	4	5.4	6,044	8.98	43.8	99.4	8.7
								3	2	1.6	8,532	9.02	1,632	98.1	94.6
4	4	1.6	4,932	97.6	672	100	88.6
								5	4	5.4	15,240	84.5	2,074	99.3	51.6
6	2	5.4	6,140	87.3	663	99.5	100
								7	3	3.5	10,305	42.8	1,887	99.5	100
8	3	3.5	10,630	45.3	1,802	99.2	100
								9	2	1.6	17,750	83	476	99.7	96.4
10	2	5.4	19,180	7.39	2,142	96.3	74.9
								11	4	1.6	18,240	8.86	536	99.1	100

Example 6 photochemical pretreatment by electromagnetic radiation

In this example, the removal or reduction of hydrogen peroxide from a common CMP slurry stream is achieved by a technique that does not add chemicals. The reduction of the oxidizing agent is not chemically performed by a pretreatment system based on photochemical reduction upon exposure to Ultraviolet (UV) electromagnetic radiation, as substantially shown in fig. 5.

The pretreatment system 610 utilized an AMD150B1/3T ultraviolet package (available from Aquonics Inc., Erlanger, Kentucky) equipped with about a 1.6 gallon UV cell 612 with 185nm wavelength, 130027-. The lamp operates at about 1KW and is powered by a power supply 614. A solution to be treated, prepared substantially as described below, is pumped from feed tank 616 through medium pressure uv tank 612 at a flow rate of about 0.75gpm with pump 618. The UV radiation dose applied at this flow rate was about 4,000 microwatts/cc. The irradiated fluid is collected in collection tank 620.

The slurry stream consisted of a mixture of commercially available copper CMP slurry concentrates based on silica and silica diluted in deionized water at a ratio of about 0.5: 20. The pH of the slurry stream is adjusted to about 3 using sulfuric acid. The metal species was added to the slurry stream as copper sulfate pentahydrate. The oxidant was added to the solution using a calculated aliquot of about 30% electronic grade hydrogen peroxide. The concentrations of the oxidizing agent and the metal species prior to treatment are listed in table 9. The data indicate that pretreatment systems incorporating UV radiation technology can reduce the oxidant concentration.

These tests did not use ion exchange resins, but focused on removing or reducing the concentration of oxidizing species by photochemical means. However, as shown in the experiments of the above examples, metal species (copper) are effectively removed using one or more embodiments of the treatment system of the present invention.

Higher UV dose levels and longer residence times in the UV cell are desirable and other techniques may further promote the reduction of oxidizer species, but as indicated in the above examples, particularly as indicated in examples 4 and 5, removal of metal can be achieved without the need to remove all of the oxidizer species.

TABLE 9 decomposition of Hydrogen peroxide by radiation

Testing	pH	Flow rate (gpm)	Total solids (mg/l)	H of inflow2O2(mg/l)	Copper inflow (mg/l)	H2O2Reduction (%)
							1	6.6	0.75	3,500	470	30	15
2	3	0.75	3,500	300	30	33
							3	3	0.75	3,500	200	30	18

While the invention has been described in conjunction with several embodiments, it is to be understood that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the aforegoing description. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the spirit and scope of the appended claims.

Having now described certain exemplary embodiments of the invention, it will be apparent to those skilled in the art that the foregoing embodiments, which are set forth by way of example only, are presented for purposes of illustration and not of limitation. Numerous variations and other embodiments are within the knowledge of one of ordinary skill in the art and are considered to be within the scope of the present invention. More specifically, while many of the embodiments described herein relate to specific combinations of method acts or system elements, it should be understood that those acts and those elements may be combined in other ways. For example, the present invention contemplates the use of a fluidized bed or similar unit operation wherein the ion exchange medium is effectively fluidized by appropriately introducing the fluid to be treated at a sufficient flow rate at one or more bottom inlets.

Furthermore, acts, elements and features discussed only in connection with one embodiment are not intended to be excluded from a similar role in other embodiments. It should also be appreciated that various changes, alterations, and modifications will readily occur to those skilled in the art, and that such changes, alterations, and modifications are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention.

Further, it should be understood that the present invention relates to each feature, system, subsystem, or technique described herein and any combination of two or more features, systems, subsystems, or techniques described herein and any combination of two or more features, systems, subsystems, and/or methods, if such features, systems, subsystems, and techniques are not mutually inconsistent, is considered to be included within the scope of the present invention as encompassed by the claims.

Ordinal terms such as "first," "second," etc., used to modify a claimed element do not by itself connote any priority, importance, or precedence of one over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one element having a certain name from another element having a same name (but for use of the ordinal term).

It will also be appreciated by those of skill in the art that the parameters and configurations described herein are for illustration, and that actual parameters and/or configurations will depend upon the specific application for which the systems and techniques of the present invention are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention. It is, therefore, to be understood that the embodiments described herein are for illustration only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described.

Claims (30)

1. A method of treating a slurry stream, the method comprising:

providing a slurry stream comprising at least one metal in a concentration of at least about 50mg/l and at least one oxidizing agent; and

introducing the slurry stream into an ion exchange column.

2. The method of claim 1, wherein the ion exchange column comprises an ion exchange material comprising at least one complexing group.

3. The process of claim 1 wherein the ion exchange column comprises an ion exchange material comprising at least one pendant functional group selected from the group consisting of iminodiacetic acid, polyamines, bis (picolyl) amines, and aminophosphonic acids.

4. The method of claim 2, wherein the ion exchange material comprises iminodiacetic acid functional groups.

5. The method of claim 1, wherein the concentration of the oxidizing agent is less than about 1,500 mg/l.

6. The method of claim 5, wherein the oxidizing agent comprises at least one selected from the group consisting of iodates, periodates, bromates, perbromates, chlorates, perchlorates, peroxides, nitrate compounds, persulfate compounds, permanganate compounds, and chromate compounds.

7. The method of claim 6, wherein the oxidizing agent comprises at least one compound selected from the group consisting of nitric acid, hydrogen peroxide, ferric nitrate, and ammonium persulfate.

8. The method of claim 7, wherein the at least one metal comprises a metal selected from the group consisting of copper, lead, nickel, zinc, cobalt, cadmium, iron, tantalum, silver, gold, platinum, palladium, iridium, rhodium, ruthenium, gallium, manganese, tungsten, hafnium, and mixtures thereof.

9. The method of claim 8, wherein the at least one metal is copper.

10. The method of claim 9, wherein the slurry stream comprises particulate matter having a diameter of about 0.001 μm to about 1 μm.

11. The method of claim 10, wherein the concentration of the particulates in the slurry stream is from about 50mg/l to about 20,000 mg/l.

12. The method of claim 1, wherein no pretreatment is performed in a carbon column to remove the at least one oxidant prior to performing the step of introducing the slurry stream into the ion exchange column.

13. The method of claim 1, further comprising the step of neutralizing the at least one oxidizing agent.

14. The method of claim 13, wherein the neutralizing step comprises adding at least one reducing species to the slurry stream.

15. The method of claim 13, wherein the step of neutralizing comprises rendering the oxidizing agent inactive by chemical, electrochemical, photochemical or thermochemical means.

16. A method of treating a chemical mechanical polishing slurry stream, said method comprising introducing said slurry stream into a treatment system consisting essentially of at least one ion exchange unit comprising a chelating ion exchange resin.

17. The method of claim 16, wherein the chelating ion exchange resin comprises iminodiacetic acid functional groups.

18. The method of claim 17, wherein the slurry stream comprises solids having a diameter of about 0.001 μm to about 1 μm.

19. The method of claim 18, further comprising introducing the slurry stream into a pretreatment system that chemically, electrochemically, photochemically, or thermochemically neutralizes any oxidizing species in the slurry stream prior to performing the step of introducing the slurry stream into the treatment system.

20. A method of manufacturing an electronic component, the method comprising:

chemically-mechanically polishing the electronic component using a slurry; and

introducing at least a portion of the slurry into a treatment system consisting essentially of an ion exchange column comprising an ion exchange material comprising iminodiacetic acid functional groups.

21. The method of claim 20, wherein the slurry comprises at least one oxidizing agent at a concentration of at least about 50 mg/l.

22. The method of claim 21, wherein the slurry comprises at least one metal species selected from the group consisting of copper, lead, nickel, zinc, cobalt, cadmium, iron, tantalum, silver, gold, platinum, palladium, iridium, rhodium, ruthenium, gallium, hafnium, manganese, and tungsten.

23. A treatment system for treating a slurry stream comprising at least one metal and at least one oxidizing species at a concentration of at least about 50mg/l, the treatment system comprising:

an inlet in fluid communication with the source of the slurry stream; and

means for reducing the concentration of the at least one metal from the slurry stream.

24. The treatment system of claim 23, wherein the at least one metal is a metal selected from the group consisting of copper, lead, nickel, zinc, cobalt, cadmium, iron, tantalum, silver, gold, platinum, palladium, iridium, rhodium, ruthenium, gallium, manganese, hafnium, and tungsten.

25. The treatment system of claim 23, wherein the at least one oxidizing agent is a member selected from the group consisting of hydrogen peroxide, ferric nitrate, and ammonium persulfate.

26. The treatment system of claim 23, further comprising means for neutralizing said at least one oxidizing agent.

27. The treatment system of claim 26, wherein the means for neutralizing the at least one oxidizing agent electrochemically, photochemically, and/or thermochemically reduces the concentration of the at least one oxidizing agent.

28. A method for facilitating treatment of a slurry stream containing at least one metal species, said method comprising providing a treatment system consisting essentially of an ion exchange column packed with an ion exchange medium, wherein said ion exchange medium comprises at least one pendant functional group capable of forming a complex with said at least one metal species.

29. The method of claim 28, further comprising the step of placing an inlet of the treatment system in fluid communication with a source of the slurry stream.

30. The method of claim 28, further comprising the step of introducing the slurry stream into the treatment system.