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Closed loop automated matrix removalRelated Patent Categories: Chemical Apparatus And Process Disinfecting, Deodorizing, Preserving, Or Sterilizing, Analyzer, Structured Indicator, Or Manipulative Laboratory Device, Miscellaneous Laboratory Apparatus And Elements, Per SeClosed loop automated matrix removal description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060133964, Closed loop automated matrix removal. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATION DATA [0001] This application is a continuation-in-part of U.S. application Ser. No. 10/641,946, filed Aug. 15, 2003, the contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD [0002] The present invention relates generally to chemical analysis, and more particularly to apparatus for the removal of an interfering matrix prior to chemical analysis. BACKGROUND [0003] Automated systems for measuring the concentration of analytes in a sample have been developed using a number of analytical techniques such as mass spectrometry. For example, co-assigned U.S. application Ser. No. 10/094,394, entitled "Automated In-Process Ratio Mass Spectrometry For Characterizing Constituents," filed Mar. 8, 2002, the contents of which are hereby incorporated by reference in their entirety, discloses an automated in-process mass spectrometry (IPMS) apparatus for detecting, identifying, and quantifying chemical constituents and their reaction products in process solutions. [0004] One type of process solution which an IPMS apparatus may analyze is a copper electroplating bath for the deposition of copper structures on semiconductor wafers. The bath comprises a relatively concentrated acidic aqueous copper sulfate solution. Plating topology is controlled by organic plating solution additives within the copper sulfate solution that function to either suppress or accelerate the plating process. These additives experience electrochemical breakdown during the plating process and can be lost by drag out or by becoming trapped within the plated film. However, the achievement of void-free plating in the vias and trenches of sub-micron high-aspect-ratio structures requires very tight control of additive levels. Unlike indirect measurement methods such as cyclic voltametric stripping (CVS) that monitor the effectiveness of the plating solution, the IPMS apparatus discussed above allows a user to directly measure trace component concentration as well as constituent concentration (including breakdown products) in the electroplating bath to ensure a defect-free deposition process. [0005] High sensitivity quantification of the organic additives and their breakdown by-products in the electroplating bath is hampered by the relatively high concentration of a matrix of sulfuric acid and copper sulfate within the bath. These relatively high concentrations of protons, sulfate, and copper ions obscure the detection and quantification of constituents such as organic additives because ionization of the higher concentration ions is statistically more likely in the ionization source of the mass spectrometer. Thus, the matrix of copper sulfate and sulfuric acid should be removed from the sample to more accurately quantify the organic additive concentrations. Similarly, other metrology techniques such as flow injection analysis and chromatography often require the removal of chemical matrices that may hamper the quantification of an analyte of interest. U.S. application Ser. No. 10/641,946 discloses an automated matrix removal module in which a reagent is mixed with a sample having an interfering matrix so that the matrix may be removed prior to quantification of the analyte(s) of interest. The reagent reacts with the matrix to form a precipitate, which is then removed using a filter. [0006] The automated matrix removal module disclosed in U.S. application Ser. No. 10/641,946 advantageously includes a back-flush cycle to cleanse the filter such that the module may remove matrix from samples continually for periods of months. However, addition of an appropriate amount of reagent depends upon the concentration of the interfering matrix. For example, in some instances it may be desirable to under-precipitate the matrix such that some matrix remains in the filtered sample. Alternatively, it may be desirable to "over-precipitate" the matrix such that some un-reacted reagent remains in the filtered sample. Attaining the desired degree of precipitation can be difficult, however, because the concentration of the matrix may change. For example, with regard to a copper plating bath, both copper sulfate and sulfuric acid can be consumed during a plating operation as well as being physically removed from the bath due to wafer removal. In addition, evaporation can occur, thereby changing copper sulfate and sulfuric acid concentrations. Moreover, replenishment of additives in the bath can also cause the matrix concentration to change if corresponding amounts of sulfuric acid and copper sulfate are not added simultaneously. [0007] The potentially-dynamic nature of a matrix concentration thus makes matrix removal problematic. For example, a matrix concentration may be assumed to be static such that a fixed amount of reagent is always added to the sample within the automated matrix removal module. In such a case, the degree of precipitation will increase if the matrix concentration decreases such as described earlier with regard to a copper plating bath. Over time, an undesired over-precipitation may occur. Alternatively, should the matrix concentration gradually increase, the degree of precipitation would gradually decrease until an undesired under-precipitation occurs. [0008] Accordingly, there is a need in the art for automated systems for the removal of interfering matrices prior to a chemical analysis which dynamically respond to changes in concentration of the interfering matrices. SUMMARY [0009] In accordance with the present invention, an apparatus for the automated removal of a matrix from a solution containing an analyte of interest is provided. The apparatus includes: at least one analytical instrument operable to measure a concentration of the matrix in a sample of the solution; a source of reagent, the reagent being reactive with the matrix to form a precipitate; a reaction vessel; and a filter, wherein the apparatus has a filtering configuration in which a volume of the solution and a volume of the reagent react in the reaction vessel to form a reaction mixture that is filtered through the filter, the volume of the reagent being based upon the matrix concentration measurement, the apparatus having a flushing configuration in which the filter is back flushed with a solvent. [0010] In accordance with another aspect of the invention, an apparatus is provided that includes: a sample extraction module operable to extract sample from a selected one of a plurality of process solution baths; at least one dilution and spiking module operable to spike and dilute extracted sample to form a processed solution; a source of reagent solution reactive with a matrix in the processed solution to form a precipitate; a plurality of matrix removal modules, each matrix removal module operable in a mixing cycle to mix the processed solution with the reagent solution to form a reaction mixture having the precipitate and to filter the precipitate from the reaction mixture through a filter to form a filtered solution, each matrix removal module operable in a flushing cycle to flush the filter; and [0011] a control system to control the mixing and flushing cycles of the plurality of matrix removal modules such that as one matrix removal module is in the mixing cycle another matrix removal module is in the flushing cycle. [0012] In accordance with another aspect of the invention, an apparatus for the automated removal of a matrix from a solution containing an analyte of interest is provided. The apparatus includes: at least one analytical instrument operable to periodically measure a concentration of the matrix; a source of reagent, the reagent being reactive with the matrix to neutralize the matrix; and a reaction vessel, wherein the apparatus has a neutralizing configuration in which a volume of the solution and a volume of the reagent react in the reaction to form a neutralized mixture, the volume of the reagent being based upon a most-recent matrix concentration measurement by the analytical instrument. BRIEF DESCRIPTION OF THE DRAWINGS [0013] FIG. 1 is an illustration of an automated matrix removal module according to an embodiment of the invention. [0014] FIG. 2 is an illustration of an automated matrix removal module including a mixing tee according to an embodiment of the invention. [0015] FIG. 3 is an illustration of an IPMS system incorporating a plurality of closed loop automated matrix removal modules. [0016] Use of the same reference symbols in different figures indicates similar or identical items. DETAILED DESCRIPTION [0017] Reference will now be made in detail to one or more embodiments of the invention. While the invention will be described with respect to these embodiments, it should be understood that the invention is not limited to any particular embodiment. On the contrary, the invention includes alternatives, modifications, and equivalents as may come within the spirit and scope of the appended claims. Furthermore, in the following description, numerous specific details are set forth to provide a thorough understanding of the invention. The invention may be practiced without some or all of these specific details. In other instances, well-known structures and principles of operation have not been described in detail to avoid obscuring the invention. [0018] FIG. 1 illustrates an exemplary automated matrix removal module 100. Module 100 includes a pump such as syringe pump 105. Syringe pump 105 is connected to a conduit 110 when a three-way valve EV1 is properly actuated. Three-way valve EV1 functions to connect syringe pump 105 to either conduit 110 or to another three-way valve EV3. Conduit 110 is connected to a source (not illustrated) of a sample solution containing an analyte which will be analyzed by a chemical analysis or metrology instrument (also not illustrated) after processing by module 100. Typical chemical metrology instruments include mass spectrometers, chromatography systems such as high performance liquid chromatography (HPLC), and flow injection analysis (FIA) systems. It will be appreciated, however, that the present invention is not limited by the type of chemical metrology instrument used after processing by module 100. [0019] Regardless of the type of chemical metrology instrument that will be used to characterize the analyte of interest in the sample solution, the performance of this instrument may be hampered by the presence of an interfering chemical matrix. As used herein, "matrix" will be understood to denote constituent(s) within the sample solution that hamper analysis of the analyte of interest by the chemical analysis or metrology tool. For example, as discussed earlier, copper sulfate and sulfuric acid act as chemical interferents in the characterization of organic additives within a copper electroplating solution by a mass spectrometer. This interference results from the hydrogen, copper, and sulfate ions being preferentially ionized within the mass spectrometer due to their relatively-high concentration, thereby obscuring the measurement of the organic additive concentrations. The acid and copper sulfate interferents may also be denoted as a "matrix" which must be removed before characterization of the organic additives. In general, a matrix may comprise a plurality of chemical species. Continue reading about Closed loop automated matrix removal... Full patent description for Closed loop automated matrix removal Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Closed loop automated matrix removal patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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