Slurry recycling in a chemical-mechanical polishing process

Abstract

An apparatus for recycling slurry includes a reservoir configured to receive and hold slurry collected from a CMP tool, at least one sensor configured to monitor one or more characteristics of the slurry held in the reservoir, and a controller configured to receive information provided by the at least one sensor regarding the one or more characteristics of the slurry.

Description

Attorney Docket No. 5308.3543.WOSLURRY RECYCLING IN A CHEMICAL-MECHANICAL POLISHING PROCESSCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] The present application claims priority to U.S. Patent Application Serial No.18 / 945,624 filed November 13, 2024, the entire content of which is incorporated herein by reference.FIELD

[0002] The present disclosure relates generally to chemical-mechanical polishing (CMP) for semiconductor fabrication, and more particularly to methods for recycling slurry used by a CMP tool in a CMP process.BACKGROUND

[0003] CMP is a well-known technique for selectively removing materials for topography planarization and device structure formation in semiconductor fabrication. The selective material removal is achieved by using a chemical reaction in combination with mechanical abrasion with slurries containing chemical formulations and large numbers of suspended abrasive particles. During polishing, slurry particles are pressed onto a wafer surface.

[0004] Typical CMP slurries consist of nano-sized abrasive particles suspended in an acidic or basic solution. A chemical reaction softens the wafer material during mechanical abrasion. The abrasive particles have a size distribution which directly affects critical semiconductor fabrication parameters including material rate of removal, planarization variance and wafer defects. The typical size range of CMP abrasive particles is about 50 - 250 nanometers (nm).SUMMARY

[0005] The present inventive concept, as manifested in embodiments disclosed herein, is directed to apparatus, methods and systems for recycling (i.e., reclaiming) slurry used by a CMP tool in a CMP process during semiconductor fabrication (e.g., silicon carbide (SiC) device fabrication).Attorney Docket No. 5308.3543.WO

[0006] In accordance with an embodiment of the present disclosure, an apparatus for recycling slurry includes a reservoir configured to receive and hold slurry collected from a CMP tool, at least one sensor configured to monitor one or more characteristics of the slurry held in the reservoir, and a controller configured to receive information provided by the at least one sensor regarding the one or more characteristics of the slurry. The controller may be further configured to refresh the slurry when the one or more characteristics of the slurry is outside a prescribed threshold, and to direct the first filtered slurry to the CMP tool when the one or more characteristics of the slurry are within the prescribed threshold. In some embodiments, the apparatus may further include a diverter valve between the CMP tool and the reservoir, the diverter valve configured to discard the slurry collected from the CMP tool when the CMP tool is operating outside of a first CMP processing window, and to direct the slurry collected from the CMP tool to the reservoir when the CMP tool is operating within the first CMP processing window.

[0007] In one or more embodiments, the apparatus may further include a slurry collection tray coupled to the CMP tool, the slurry collection tray configured to receive slurry from a platen of the CMP tool during a first CMP processing window and to prevent collection of the slurry from the CMP tool when the CMP tool is operating outside of the first CMP processing window.

[0008] In accordance with another embodiment of the present disclosure, an apparatus for recycling slurry includes a reservoir configured to receive and hold slurry collected from a CMP tool, and a controller configured to selectively divert slurry collected from the CMP tool to the reservoir. The apparatus may further include a diverter coupled between the CMP tool, the reservoir and a drain. In one or more embodiments, the controller may be configured to control the diverter to pass the slurry collected from the CMP tool to the reservoir during a steady-state CMP processing window that excludes an initial start-up period of CMP processing and an end cleaning period of the CMP processing.

[0009] In accordance with an embodiment of the present disclosure, a method of recycling slurry includes: determining whether a CMP tool is in a steady-state CMP processing window of operation; discarding the slurry when the CMP tool is operating outside of the steady-state CMP processing window; and directing the slurry collected from the CMP tool for holding in a reservoir.Attorney Docket No. 5308.3543.WO

[0010] In accordance with another embodiment of the present disclosure, a method of recycling slurry includes: collecting slurry from a CMP tool; passing the collected slurry to a reservoir; monitoring one or more properties of the slurry held in the reservoir to determine whether the one or more properties of the slurry are outside of a prescribed threshold; refreshing the slurry held in the reservoir when the one or more properties of the slurry are outside of the prescribed threshold; and when the one or more properties of the slurry are within the prescribed threshold, fdtering the slurry held in the reservoir to provide a recycled slurry, and directing the recycled slurry to the CMP tool.

[0011] According to another embodiment of the present disclosure, a CMP tool with an integrated slurry collection apparatus includes a slurry collector, configured to block slurry when at least a portion of the slurry collector is in a first position, and the slurry collector receives slurry when at least the portion of the slurry collector is in a second position.

[0012] Aspects of the present inventive concept can provide substantial beneficial technical effects. By way of example only and without limitation, techniques according to embodiments of the present disclosure may provide one or more of the following advantages, among other benefits:reduces the amount of slurry consumed by a CMP tool during CMP processing, thereby reducing the overall cost of semiconductor fabrication;provides a simple solution for recycling slurry during CMP processing, without the use of complex suction (i.e., vacuum) systems;reduces the quantity of chemical waste, thereby easing compliance with environmental standards and regulations; andreduces the likelihood of contamination in the recycled slurry.

[0013] These and other features and advantages of the present inventive concept will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings.Attorney Docket No. 5308.3543.WOBRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which are included to provide a further understanding of the inventive concept and are incorporated in and constitute a part of this application, are presented by way of example only and without limitation, wherein like reference numerals (when used) indicate corresponding elements throughout the several views, and wherein:

[0015] FIG. 1 A is schematic plan view depicting an illustrative single-wafer CMP tool which can be modified to incorporate aspects of the present inventive concept;

[0016] FIG. IB is a schematic side view depicting the illustrative CMP tool shown in FIG. 1A;

[0017] FIG. 2A is a block diagram depicting at least a portion of an illustrative simplified CMP slurry recycling system, according to one or more embodiments of the present inventive concept;

[0018] FIG. 2B is a block diagram depicting at least a portion of an illustrative CMP slurry recycling system, according to one or more embodiments of the present inventive concept;

[0019] FIG. 2C is a block diagram depicting at least a portion of an illustrative CMP slurry recycling system configured to recycle slurry from a plurality of CMP tools, according to one or more embodiments of the present inventive concept;

[0020] FIGS. 3 A and 3B are schematic perspective views depicting an illustrative slurry collection tray with and without a cover, respectively, suitable for use with the CMP slurry recycling system shown in FIG. 2A, according to embodiments of the present inventive concept;

[0021] FIGS. 3C and 3D are top plan views depicting the illustrative slurry collection tray shown in FIG. 3A integrated with a CMP tool in disengaged and engaged positions, respectively, according to one or more embodiments of the present inventive concept;

[0022] FIG. 4 is a flow diagram depicting a simplified example method for recycling slurry in a CMP tool, according to one or more embodiments of the present inventive concept; and

[0023] FIGS. 5A and 5B are flow diagrams depicting at least a portion of an example method for recycling slurry in a CMP tool, according to one or more embodiments of the present inventive concept.Attorney Docket No. 5308.3543.WO

[0024] It is to be appreciated that elements in the figures may be illustrated for simplicity and clarity. Common but well-understood elements that may be useful or necessary in a commercially feasible embodiment are not necessarily shown in order to facilitate a less hindered view of the illustrated embodiments.DETAILED DESCRIPTION

[0025] Principles of the present invention, as manifested in embodiments disclosed herein, are described in the context of apparatus and methods for recycling (i.e., reclaiming) slurry used in a chemical-mechanical polishing (CMP) process for semiconductor manufacturing. It is to be appreciated, however, that the invention is not limited to the specific apparatus and methods illustratively shown and described herein. As used herein, the term “and / or” is intended to include any and all combinations of one or more of the associated listed items. It will become apparent to those skilled in the art given the teachings herein that numerous modifications to the embodiments shown are contemplated and are within the scope of the present disclosure. That is, no limitations with respect to the embodiments shown and described herein are intended or should be inferred. Furthermore, upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the present disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the present disclosure and the accompanying claims.

[0026] Embodiments may be described herein with reference to the example illustrations shown in the accompanying drawings. It is to be understood that the actual dimensions of the structures and / or elements shown in the drawings may not be to scale and may therefore be different. Furthermore, variations from the shapes depicted in the drawings as a result, for example, of manufacturing techniques and / or tolerances, are contemplated. For example, sizes of structures and / or elements may be exaggerated relative to other structures and / or elements for illustrative purposes. Thus, the structures and / or elements depicted in the drawings are schematic and their shapes and dimensions are not intended to illustrate the precise shapes and dimensions of the structures and / or elements and are not intended to limit the scope of the present disclosure. Common elements throughout the figures may be shown and referencedAttorney Docket No. 5308.3543.WOherein with common reference numbers and as such their descriptions may not be subsequently repeated.

[0027] CMP is one of the most expensive processes in semiconductor fabrication, and slurry is the most costly consumable among all consumables in the fabrication process. Conventional single-wafer CMP tools utilize a significant amount of slurry. A majority of the slurry consumed by the CMP tool barely grazes the surface of the wafer and goes straight to drain. This problem is particularly severe for SiC CMP processing, due at least in part to the lengthy process times required as a result of the hardness and chemical inertness of the SiC material. Longer CMP times use large volumes of slurry and generate significant waste. Thus, standard CMP tools and CMP processing, especially SiC CMP processing, is costly and wasteful.

[0028] FIG. 1A is schematic plan view depicting an illustrative single-wafer CMP tool 100 which can be modified to incorporate aspects of the present inventive concept. FIG. IB is a schematic side view depicting the CMP tool 100 shown in FIG. 1A. Referring to FIGS. 1 A and IB, the CMP tool 100 includes a flat, disc-shaped rotatable platen 102 adapted to support a polishing pad 104 for performing CMP for a wafer 106 that is to be polished. The platen 102 is mounted on a cylindrical shaft 108 which connects the platen to a motor or other drive mechanism (not explicitly shown) configured to rotate the platen 102 at a controlled speed. The pad 104 is provided on an upper surface of the platen 102 and is configured to cover all or a substantial portion of the platen 102. A diameter of the pad 104 is typically greater than a diameter of the wafer 106.

[0029] The wafer 106 that is being polished may be mounted upside-down so that an upper surface of the wafer 106 contacts an upper surface of the pad 104 during the CMP process. The wafer 106 may be supported by a carrier 110 which is configured to rotate the wafer 106 at a controlled speed. The platen 102, with the pad 104 affixed thereto, and the carrier 110, with the wafer 106 affixed thereto, may be rotated with different axes of rotation (i.e., non-concentric) and speed. Independently rotating the pad 104 and wafer 106 relative to each other facilitates the removal of material and tends to even out any irregular topography, thereby increasing the planarity of the wafer 106. In addition to rotation of the carrier 110 and platen 102, there is a downward force applied on wafer 106 to facilitate material removal.Attorney Docket No. 5308.3543.WO

[0030] The carrier 110 may include a flat, disc-shaped platform for receiving the wafer 106 and a shaft connecting the platform to a motor or other drive mechanism (not explicitly shown) for rotating the wafer 106. A backing film or membrane 112 may be provided on the carrier 110 between the wafer 106 and the platform of the carrier 110, and a retaining ring or other fastener may be provided to secure the wafer 106 to the carrier 110 in a desired horizontal position during the polishing process. In some embodiments, a vacuum mechanism may be used to fix the wafer 106 to the carrier 110.

[0031] During CMP, a slurry is deposited onto the surface of the pad 104 through a slurry supply tube 114 or other slurry introduction mechanism. The slurry is generally an abrasive colloid (e.g., containing alumina, silica, ceria (CeCh), zirconia, magnesium dioxide, etc.), but embodiments are not limited thereto. Both the platen 102 and the carrier 110 are then rotated. A downward pressure (i.e., force) is then applied to the carrier 110, pushing the wafer 106 against the pad 104. The amount of pressure applied to the carrier 110 may be controlled as a function of one or more polishing parameters, including an abrasiveness of the slurry mixture used for CMP and the amount of material to be removed from the wafer 106, among other factors.

[0032] As polishing progresses, machining chips, product reactions and solid bodies in the slurry may produce small holes in the pad 104, which can cause the machining quality to deteriorate. Conditioning of the pad 104 may be performed to restore a surface of the pad 104; conditioning also helps to maintain the planarity of the pad 104. To accomplish this, the CMP tool 100 may optionally include a pad conditioner 116 adapted to contact the upper surface of the pad 104. The pad conditioner 116 may be attached to a conditioner arm 118 configured to maintain a position of the pad conditioner 116 on the surface of the pad 104. The conditioner arm 118 may be configured to rotate the pad conditioner 116 with respect to the surface of the pad 104. The conditioner arm 118 may also be configured to sweep the conditioner pad 116 horizontally across the upper surface of the pad 104 as the pad 104 is rotating. The pad conditioner 116 is configured to restore the surface of the pad 104 to its prime condition, correct the shape (e.g., planarity) of the pad 104, and maintain the wafer polishing rate. In this regard, the pad conditioner 116 can significantly prolong the life of the pad 104.

[0033] As previously stated, CMP is perhaps the most expensive fabrication process in semiconductor manufacturing, and slurry is the most costly consumable among all otherAttorney Docket No. 5308.3543.WOconsumables in the overall fabrication process. While single-wafer CMP toolsets may offer more wafer-level control compared to batch (i.e., multi-wafer) CMP toolsets, the per-wafer cost when using batch-level CMP processing may be lower. That said, batch CMP toolsets use higher flow rates and have longer processing times than single-wafer CMP toolsets, and therefore also utilize a significant amount of slurry. Aspects of the present disclosure are directed to slurry recycling (i.e., reclaiming) techniques for use in a CMP system. Although single-wafer CMP toolsets, particularly single-wafer CMP toolsets adapted for handling 200-millimeter (mm) or larger silicon carbide (SiC) wafers, may obtain greater benefits using the slurry recycling techniques according to embodiments of the inventive concept, batch CMP toolsets may also receive a measurable reduction in CMP costs using techniques of the inventive concept.

[0034] FIG. 2A is a block diagram depicting at least a portion of an illustrative simplified CMP slurry recycling system 200, according to one or more embodiments of the inventive concept. An objective of the CMP slurry recycling system 200 is to collect the slurry and feed it back to the CMP toolset without sacrificing characteristics of the slurry (e.g., pH, particle size, and / or slurry composition) which could otherwise degrade CMP performance and / or damage the wafer being processed. Referring to FIG. 2A, the CMP slurry recycling system 200 includes at least one CMP tool 202, which may be a single-wafer CMP toolset adapted to process 200-mm or larger SiC wafers, although embodiments are not limited thereto. The CMP slurry recycling system 200 further includes a slurry diversion mechanism 204 configured to receive slurry from the CMP tool 202 and provide the collected slurry to at least one slurry recycle vessel 210.

[0035] In one or more embodiments, the slurry diversion mechanism 204 may comprise a valve (e.g., diverter valve) configured to selectively open during a prescribed stage (e.g., an intermediate stage) of a CMP processing cycle for providing the received slurry to the slurry recycle vessel(s) 210. In some embodiments, the slurry diversion mechanism 204 may be integrated with the CMP tool 202. In some embodiments, the slurry diversion mechanism 204 may comprise a blocking element configured to enable collection of slurry during the prescribed stage of the CMP processing cycle and to disable (i.e., stop or block) the collection of slurry when the CMP tool is operating outside of the prescribed stage of the CMP processing cycle.Attorney Docket No. 5308.3543.WO

[0036] The CMP slurry recycling system 200 further includes a slurry redistribution mechanism 218 configured to receive slurry from the slurry recycle vessel(s) 210 and to provide reconditioned (i.e., refreshed) slurry to the CMP tool(s) 202. The slurry redistribution mechanism 218 may be configured to measure or monitor one or more properties of the received slurry in the slurry recycle vessel(s) 210 and to refresh or recondition the slurry when one or more of the measured properties is outside of a prescribed threshold or range. In one or more embodiments, refreshing of the slurry may include performing additive reconditioning of the slurry in the vessel 210; that is, adding something (e.g., a solution, particles, etc.) to the slurry to change one or more properties of the slurry (e.g., chemical composition). In other embodiments, subtractive and / or additive reconditioning of the slurry may be performed; that is, adding something to or removing something from (e.g., filtering) the slurry to change one or more properties of the slurry.

[0037] FIG. 2B is a block diagram depicting at least a portion of an illustrative implementation of the CMP slurry recycling system 200 of FIG. 2A, according to one or more embodiments. Referring to FIG. 2B, the CMP slurry recycling system 200 includes at least one CMP tool 202. The CMP tool 202 may include a slurry collection mechanism 203, which may comprise, for example, a platen shield and a slurry catch (i.e., collection) tray. Embodiments of a slurry catch tray suitable for use with the present inventive concept will be described in further detail below. Various other implementations of the slurry collection mechanism 203 are contemplated and are within the scope of the inventive concept, including the use of vacuum slurry collection techniques, as will become apparent to those skilled in the art given the teachings herein.

[0038] Slurry received from the CMP tool 202 using the slurry collection mechanism 203 may be supplied to a slurry diversion mechanism 204. During a first interval of a CMP processing cycle, the slurry diversion mechanism 204 may be configured to provide slurry received from the CMP tool(s) 202 to a slurry recycle vessel(s) 210. The CMP slurry recycling system 200 further includes a slurry redistribution mechanism 218 configured to receive slurry from the slurry recycle vessel(s) 210 and to provide reconditioned (i.e., refreshed) slurry to the CMP tool 202. In some embodiments, the slurry recycle vessel 210 may comprise a plurality of vessels connected in parallel or serially to monitor and / or perform different or progressive reconditioning steps (i.e., processes).Attorney Docket No. 5308.3543.WO

[0039] In one or more embodiments, the slurry diversion mechanism 204 may include, for example, a two-way valve 205, although embodiments are not limited thereto. The valve 205 may be external to the slurry collection mechanism 203 or it may be integrated within the slurry collection mechanism 203. Optionally, the valve 205 may provide the received slurry, via a first output port thereof, to a first filter 206 during the first interval of the CMP processing cycle and, during a second interval of the CMP processing cycle, the valve 205 may direct the received slurry, via a second output port thereof, to a drain where the slurry is discarded.

[0040] The first interval of the CMP processing cycle for a given wafer may be defined as an intermediate stage CMP processing window of the CMP processing cycle during which the slurry is generally not diluted and / or contaminated by deionized water (DIW) and / or cleaning solutions containing redox-active chemistries. The second interval of the CMP processing cycle may be defined as an interval(s) of the CMP processing cycle, outside of the first interval, during which there is a higher likelihood of contamination of the slurry. For example, during a final portion of the CMP polishing (e.g., the last minute or so of the CMP processing cycle), the wafer is de-chucked from the CMP tool and the polishing pad is reconditioned, which generally involves the use of cleaning solutions (i.e., cleaning chemistry). During an initial (start-up) portion of the CMP polishing (e.g., the first 30 seconds or so), some cleaning solution may remain on the polishing pad. Slurry collected during this second interval of the CMP processing cycle therefore has a higher likelihood of being contaminated by these cleaning solutions.

[0041] CMP processing of SiC wafers presents significant challenges compared to CMP processing of silicon wafers, due at least in part to the complex properties of the SiC material and the use of interfering chemistries for SiC CMP processing which can lead to rapid degradation of the slurry. Some properties of the SiC material that may make SiC CMP processing more challenging compared to silicon CMP processing include, but are not limited to: hardness (SiC is comparable to diamond, requiring a more aggressive nature of the slurry and chemistry than silicon); brittleness and thinness (SiC wafers are about half as thick as silicon wafers and require special carriers to prevent breakage, cracking or chipping); transparency (SiC wafers are highly transparent, making it difficult to sense their position during processing); inertness (SiC is chemically inert, making it more difficult to planarize); and low material removal rate (SiC-optimized slurries must remove only the oxidized layer, without going too deep and creatingAttorney Docket No. 5308.3543.WOscratches). These and other factors make slurry used for SiC CMP processing significantly more expensive and toxic compared to slurry used for standard silicon CMP processing.

[0042] The first filter 206, when used, may be configured to remove suspended particles greater than a first prescribed size (e.g., about 50 - 100 pm); the first filter may be considered a coarse filter. Slurry recovered during the first portion of the CMP processing cycle may be provided to the first filter 206 through an optional check valve 208 included in the slurry diversion mechanism 204 and disposed in-line between the first output port of the diverter valve 205 and an input of the first filter 206. The check valve 208 may be a one-way valve configured to prevent back flow of the received slurry to the CMP tool 202 and / or to a drain.

[0043] Recovered slurry passing through the first filter 206, which may be referred to herein as coarsely filtered slurry, may be supplied to the slurry recycle vessel 210. The slurry recycle vessel 210 may be configured to at least temporarily hold the received slurry while inline monitoring of one or more properties (e.g., pH, particle size, etc.) of the slurry is performed, for example using an inline monitor 212. In one or more embodiments, the slurry recycle vessel 210 may include a recirculating pump (not explicitly shown) configured to mix the slurry, either continuously or at prescribed intervals, so that the suspended abrasive remains evenly distributed throughout the slurry. When slurry sits for a prolonged period of time, the abrasive particles can come out of suspension and grow in size (i.e., through particle agglomeration), thereby increasing the chance for wafer scratching to occur. Other systems (e.g., a mechanical stirrer) may be used to keep the suspended abrasive evenly distributed throughout the slurry. In some embodiments, the slurry recycle vessel 210 may be implemented as a simple conduit or tube through which the received slurry passes without being stored. In this case, recirculation of the slurry may not be required. In some embodiments, the slurry recycle vessel 210 may include a refrigeration and / or heating unit (not explicitly shown) configured to cool and / or heat the slurry, respectively, for maintaining the slurry at constant temperature (e.g., room temperature) as it is held in the vessel 210.

[0044] CMP slurries typically comprise an abrasive (i.e., colloidal particles, such as alumina, silica, manganese dioxide, etc.) suspended in an acidic or basic solution (e g., potassium permanganate, for SiC CMP slurries), although in some cases a neutral solution may be used. The inline monitor 212 may utilize inline metrologies to monitor, either continuously or atAttorney Docket No. 5308.3543.WOprescribed intervals, one or more properties of the slurry. Such inline metrologies may include, but are not limited to, pH sensors to monitor pH value (acidic or basic) of the slurry, reductionoxidation (redox) potential and conductivity to monitor slurry reactivity, spectrophotometric measurement to monitor solution / abrasive concentration, density measurement to monitor solid content, large particle counters to monitor particle sizing, etc. The inline monitor 212 may be included in the slurry redistribution mechanism 218.

[0045] By way of example only and without limitation, the inline monitor 212 may comprise at least one of a pH sensor configured to monitor a pH value of the slurry, a redox potential and conductivity sensor configured to monitor reactivity of the slurry, a spectrophotometric sensor configured to monitor solution / abrasive concentration of the slurry, a density sensor to monitor solid content in the slurry, or a particle counter configured to monitor a size of suspended particles in the slurry. pH sensors for monitoring the pH value of the slurry may use a potentiometric measurement principle, as is known in the art. Optical sensors for monitoring particle size of the slurry may measure scattered light, such as by laser diffraction, as is known in the art. Other characteristics of the coarsely filtered slurry, such as chemical content (e.g., using inline absorption spectra measurement), may be monitored alternatively or in addition to pH and / or particle size.

[0046] Measurement data (i.e., inline metrology information) from the inline monitor 212 may be used to provide feedback regarding slurry degradation. This information may be supplied to a slurry recycling controller 214. The slurry recycling controller 214 may be configured to control one or more functions of the slurry diversion mechanism 204, the slurry redistribution mechanism 218, and / or the CMP tool(s) 202. In some embodiments, the slurry recycling controller 214 is external to the slurry redistribution mechanism 218, while in other embodiments, the slurry redistribution mechanism 218 may be integrated with the slurry redistribution mechanism 218.

[0047] The slurry recycling controller 214 (e.g., microprocessor, central processing unit (CPU), etc.) may be configured to receive the metrology information from the inline monitor 212 and to refresh (i.e., recondition) the slurry in the slurry recycle vessel 210. For example, unused (i.e., fresh) slurry (e.g., potassium permanganate) may be mixed with the slurry held in the slurry recycle vessel 210 when it is determined that one or more properties of the slurry have degradedAttorney Docket No. 5308.3543.WObelow a prescribed threshold. In one or more embodiments, fresh slurry and / or other reactants used to refresh or recondition the slurry in the slurry recycle vessel 210 may be stored in a reconditioning solution container 216 in operative connection with the slurry recycle vessel 210. The reconditioning solution container 216 may be included as part of the slurry redistribution mechanism 218. Solution(s) stored in the reconditioning solution container 216 may be mixed with the slurry in the slurry recycle vessel 210 for refreshing the slurry therein. The flow of solution(s) from the reconditioning solution container 216 may be controlled by the slurry recycling controller 214.

[0048] In one or more embodiments, the slurry recycling controller 214, in conjunction with the inline monitor 212 and the reconditioning solution container 216, may be configured, for example, to raise or lower the pH of the recovered slurry, such as by feeding a base or acid solution, respectively, to the slurry recycle vessel 210 to be mixed with the recycled slurry held in the vessel. Furthermore, the slurry recycling controller 214 may be configured to add buffers to stabilize the pH of the slurry, to add ions for maintaining ionic strength (conductivity) of the slurry, and / or to add stabilizing chemistries to control slurry degradation (e.g., to control degradation of permanganate, add periodate, persulfate, etc.). In other embodiments, the slurry recycling controller 214 may include a mechanism for adding abrasive (e.g., alumina, silica, etc.) to the recovered slurry. Regardless of the mechanism(s) employed, the inline monitor 212, the slurry recycling controller 214 and the reconditioning solution container 216 may form a closed loop feedback system with the slurry recycle vessel 210 to control a quality of the recycled slurry so that one or more properties of the recycled slurry may be restored to an initial state of the slurry for continued CMP processing.

[0049] When the quality of the recycled slurry has been restored to a prescribed level based on monitoring data provided by the inline monitor 212, the slurry redistribution mechanism 218 may be configured to provide (i.e., direct) the recycled slurry held in the slurry recycle vessel(s) 210 to the CMP tool 202, optionally through a second slurry filter 220, such as by the slurry recycling controller 214 sending a control signal to the slurry redistribution mechanism 218. The second filter 220, when used, may be configured to remove suspended particles in the slurry greater than a second prescribed size (e.g., about 1 pm - 5 pm), the second prescribed size being smaller than the first prescribed size associated with the first filter 206. The second filter, which may be considered a fine filter, is configured to allow at least some of the abrasive to remain inAttorney Docket No. 5308.3543.WOthe slurry for CMP processing. Recycled slurry passing through the second filter 220, which may be referred to herein as finely filtered slurry, may be supplied to back to the CMP tool 202 for continued CMP processing.

[0050] Optionally, the slurry redistribution mechanism 218 may include a pump 219 configured to receive the slurry in the slurry recycle vessel 210 and to provide the refreshed slurry to the CMP tools 202. The pump 219 may be used, for example, when the CMP tool 202 is positioned at a higher level than the slurry recycle vessel 210 such that gravity alone cannot supply the refreshed slurry to the CMP tool 202. Although the pump 219 is shown as being connected between the slurry recycle vessel 210 and the second filter 220, the pump 219 may be disposed at other places inline between the slurry recycle vessel 210 and the CMP tool 202.

[0051] In some embodiments, the slurry redistribution mechanism 218 may optionally include a slurry vessel or reservoir 221 connected inline between the slurry recycle vessel 210 and the CMP tool 202. The slurry vessel or reservoir 221 may be used as a secondary storage mechanism to hold refreshed slurry to be provided to the CMP tool 202. This arrangement allows the slurry recycle vessel 210 to continue receiving slurry from the CMP tool 202 to be monitored and reconditioned without interrupting the flow of refreshed slurry back to the CMP tool 202.

[0052] If one or more properties of the recovered slurry have degraded to below a prescribed threshold (i.e., beyond what the slurry redistribution mechanism 218 can otherwise restore) based on inline metrology measurements, the slurry recycling controller 214 may be configured to cause the slurry recycle vessel 210 to discard the recycled slurry being held in the vessel. For example, the slurry recycle vessel 210 may include an opening (e.g., in a floor of the reservoir) with a control valve configured to release the slurry in response to a received control signal from the slurry recycling controller 214, or the slurry recycle vessel 210 may include a pump for transferring the recovered slurry out of the slurry recycle vessel 210 to the drain of the CMP slurry recycling system 200.

[0053] In one or more embodiments, the slurry recycle vessel 210 may include an overflow sensor configured to release a prescribed amount of slurry when an amount of the recovered slurry in the slurry recycle vessel 210 reaches or exceeds a prescribed threshold level. In some embodiments, the overflow sensor in the slurry recycle vessel 210 may be configured to send aAttorney Docket No. 5308.3543.WOcontrol signal to the diverter valve 205 for directing the recovered slurry to the drain, rather than allowing the slurry to be provided to the slurry recycle vessel 210. In one or more embodiments, the slurry recycle vessel 210 may be configured to have a double containment tank to catch and recycle any slurry overflow.

[0054] Although a single CMP tool 202 is depicted in FIG. 2B, it is to be appreciated that the CMP slurry recycling system 200 may be configured to recycle slurry from a plurality of CMP tools. For example, FIG. 2C is a block diagram depicting at least a portion of an illustrative CMP slurry recycling system 250 configured to collect and recycle slurry from a plurality of CMP tools, according to one or more embodiments of the present inventive concept. Referring to FIG. 2C, the CMP slurry recycling system 250 may be similar to the illustrative CMP slurry recycling system 200 shown in FIG. 2B, except that the diverter valve 205 includes multiple input ports configured to receive slurry from a plurality of CMP tools 202 A, 202B and 202C. A first slurry collection mechanism 203A may be operatively coupled to a first CMP tool 202A for conveying slurry from the first CMP tool 202A to the diverter valve 205. A second slurry collection mechanism 203B may be operatively coupled to a second CMP tool 202B for conveying slurry from the second CMP tool 202B to the diverter valve 205. Likewise, a third slurry collection mechanism 203C may be operatively coupled to a third CMP tool 202C for conveying slurry from the third CMP tool 202C to the diverter valve 205. It is to be understood that the inventive concept is not limited to any particular number of CMP tools; that is, more than three CMP tools (e.g., four or more CMP tools) or less than three CMP tools (e.g., two CMP tools) may be used, with the diverter valve 205 appropriately configured to have a number of input ports equal to or exceeding the number of CMP tools used with the CMP slurry recycling system 250.

[0055] In one or more embodiments, the diverter valve 205 in the CMP slurry recycling system 250 may be configured to open or close one or more of the input ports coupled to the slurry collection mechanism 203 A, 203B, 203C of a respective one of the CMP tools 202A, 202B, 202C as a function of one or more parameters, such as, for example, a window of operation of the CMP tools 202A, 202B, 202C (e.g., whether the CMP tool is operating outside of the steadystate CMP processing window). The one or more parameters may be monitored by the CMP tools themselves, or by an external sensing system configured to monitor such param eter(s).Attorney Docket No. 5308.3543.WO

[0056] The CMP slurry recycling system 250 may further include a second diverter valve 224 configured to provide recycled (i.e., refreshed or reconditioned) slurry from the slurry recycle vessel(s) 210 to one or more of the CMP tools 202A, 202B, 202C. In one or more embodiments, the second diverter valve 224 may include an input port for receiving recycled slurry from the slurry recycle vessel 210, and a plurality of output ports for providing the recycled slurry to the plurality of CMP tools 202A, 202B, 202C. The diverter valves 204 and 224 could be a single multi-port valve or multiple individual valves.

[0057] In one or more embodiments, the second diverter valve 224 may be controlled by the slurry recycling controller 214 or another control means (e g., processor, microcontroller, etc.) for automatically distributing the recycled slurry to one or more of the CMP tools 202A, 202B, 202C. In some embodiments, the second diverter valve 224 may be controlled by the respective CMP tools 202A, 202B, 202C. A determination as to which CMP tool(s) to distribute the recycled slurry may be based on one or more prescribed parameters monitored by the slurry recycling controller 214 and / or other monitors / sensors, such as, for example, a slurry consumption rate for each of the CMP tools 202A, 202B, 202C.

[0058] In one more embodiments, with reference again to FIG. 2B, the slurry collection mechanism 203 may comprise a slurry collection apparatus (e.g., collection tray) operatively attached to or integrated with the CMP tool 202 and configured to at least temporarily contain collected slurry from a platen shield or similar collection mechanism and direct the collected slurry to the slurry recycling system according to aspects of the inventive concept. In some embodiments, the diverter valve 205 of the slurry recycling system 200, or a portion thereof, may be integrated with the slurry collection apparatus. In one or more embodiments, the slurry collection apparatus according to aspects of the inventive concept may be movably attached to the CMP tool, such as with a slidable or pivotable connection arrangement, to enable the slurry collection apparatus to be manually and / or automatically engaged / disengaged from collecting slurry from the CMP tool as desired. For example, the slurry collection apparatus according to one or more embodiments may be engaged for slurry collection during an intermediate stage CMP processing window, which may exclude an initial start-up period of CMP processing and / or an end cleaning period of the CMP processing, and may be disengaged for slurry collection when the CMP tool is operating outside of the intermediate stage CMP processing window.Attorney Docket No. 5308.3543.WO

[0059] By way of example only and without limitation, FIGS. 3A and 3B are schematic perspective views depicting an illustrative slurry collection apparatus implemented as a slurry collection tray 300 suitable for use with a CMP slurry recycling system (e.g., CMP slurry recycling system 200 shown in FIG. 2B), according to embodiments of the inventive concept. Referring to FIG. 3A, the slurry collection tray 300 may comprise a floor or base 302, a front wall 304, a back wall 306, and two side walls 308. Each of the front wall 304, the back wall 306 and the side walls 308 may extend vertically upward from the base 302 to define an interior space within the slurry collection tray 300 where collected slurry from the platen of the CMP tool 202 (see FIG. 2B) is received.

[0060] In one or more embodiments, the back wall 306 and the front wall 304 may extend longitudinally parallel to one another and intersect the two side walls 308. A longitudinal width of the back wall 306 may be greater than a longitudinal width of the front wall 304, so that the slurry collection tray 300 has a trapezoidal shape when viewed in plan view. It is to be appreciated, however, that the inventive concept is not limited to any specific shape or dimensions of the slurry collection tray 300. For example, it is contemplated that in one or more embodiments the slurry collection tray 300 may be rectangular in shape, while in other embodiments the slurry collection tray 300 may be triangular or circular in shape.

[0061] The slurry collection tray 300 may include an opening (i.e., drain) 310 in the base 302 proximate the front wall 304. The opening 310 is configured to allow collected slurry in the slurry collection tray 300 to be provided to the slurry recycle vessel 210 (see FIG. 2B). In one or more embodiments, the base 302 of the slurry collection tray 300 may be inclined downward (i.e., having a negative slope) from the back wall 306 toward the front wall 304 so that the collected slurry flows, by action of gravity, through the opening 310. The base 302 may also be shaped (e.g., V-shaped, curved, etc.) to allow all or most of the collected slurry to flow from the side walls 308 toward the opening 310.

[0062] An angle at which the base 302 is tapered is configured to be greater than zero degrees (with zero degrees being horizontal or flat), although embodiments of the inventive concept are not limited to any specific angle of the base 302. In some embodiments, a slope of the base 302 may be configured to control a flow rate of the collected slurry in the slurry collection tray 300. A greater (i.e., steeper) angle of slope of the base 302 enables slurry in the slurry collection trayAttorney Docket No. 5308.3543.WO300 to be transferred out of the tray more quickly and into the slurry recycle reservoir (e.g., 210 in FIG. 2A), which may reduce the likelihood of contamination of the collected slurry. In some embodiments, the base 302 may be flat, such that the slurry drains through the opening 310 once a level of the slurry in the slurry collection tray 300 has reached a prescribed height. In some embodiments, one or more of the sidewalls 308 of the slurry collection tray 300 may be angled (i.e., inclined or sloped) inwardly to allow collected slurry on the sidewalls 308 to be directed toward the opening 310 in the base 302 for providing the collected slurry to the slurry recycling system 200 (see FIG. 2B).

[0063] In one or more embodiments, the front wall 304 may optionally include a cutout 312. The cutout 312 may be semi-circular in shape, extending partially downward from a top edge of the front wall 304, although embodiments are not limited thereto. The cutout 312 is configured to provide a means of grasping the slurry collection tray 300 for sliding the tray (e.g., backwards or forwards) when manually repositioning the slurry collection tray 300 to avoid collecting slurry during intervals of the CMP processing cycle in which contamination is more likely (e.g., initial start-up period and / or end cleaning period). In one or more embodiments, the slurry collection tray 300 may include an attachment structure 314, which may be configured as a hollow cylindrical structure affixed to one of the sidewalls 308 of the slurry collection tray 300. The attachment structure 314 may be adapted to receive a pin or rod for pivotal attachment to the CMP tool. This attachment arrangement may facilitate manual and / or automatic engagement / disengagement of the slurry collection tray 300 with the CMP tool.

[0064] Referring now to FIG. 3B, in some embodiments, the slurry collection tray 300 may optionally include a cover 320 provided over at least a portion of the slurry collection tray 300. The cover 320 may be supported by an upper rim 322 of the slurry collection tray 300 defined by a top edge of each of the front wall 304, the back wall 306 and / or the two side walls 308. The cover 320 may further reduce the likelihood of contaminants being introduced into the collected slurry.

[0065] In one or more embodiments, a suction (i.e., vacuum) system may be used in place of or in addition to the slurry collection tray 300. For example, when using the slurry collection tray 300, rather than relying on gravity for transferring the collected slurry to the diverter valve (e.g., 205 in FIG. 2B), the opening 310 in the base 302 of the slurry collection tray 300 may beAttorney Docket No. 5308.3543.WOomitted and a vacuum line (not explicitly shown, but implied) may be provided proximate the base 302 of the slurry collection tray 300 and coupled with the diverter valve 205 (see FIG. 2B) for providing collected slurry from the slurry collection tray 300 to the slurry recycle vessel 210 of the slurry recycling system 200 (see FIG. 2B).

[0066] FIGS. 3C and 3D are top plan views depicting the illustrative slurry collection tray 300 shown in FIG. 3A integrated with a CMP tool in disengaged and engaged positions, respectively, according to one or more embodiments. Referring to FIG. 3C, the slurry collection tray 300 is shown disengaged from a CMP tool. The CMP tool includes a platen 330 and a platen shield 332 surrounding (i.e., extending around) at least a portion of the platen 330 for directing used slurry towards an outlet 334 formed in the platen shield 332. When the slurry collection tray 300 is in the disengaged position as shown, the used slurry from the platen 330 will flow through the outlet 334 in the platen shield 332 and into a drain 336 in the CMP tool, so that the slurry is not contained in the slurry collection tray 300.

[0067] Referring to FIG. 3D, the slurry collection tray 300 is shown in an engaged position with respect to the CMP tool. When engaged with the CMP tool, the slurry collection tray 300 is positioned under the outlet 334 in the platen shield 332, so that the used slurry from the platen 330 flows into the slurry collection tray 300 and not into the drain 336 in the CMP tool. A slurry collection mechanism 338, which may be a hose coupled to the slurry collection tray 300 in a manner which enables collected slurry in the slurry collection tray 300 to be transferred (e.g., via vacuum, gravity, or other means) to another container (e.g., slurry recycle vessel(s) 210 shown in FIGS. 2A - 2C) for processing. It is to be appreciated that although the mechanism for engaging or disengaging the slurry collection tray 300 with the CMP tool as depicted in FIGS. 3C and 3D may be manual, the use of fully or partially automated engagement means are similarly contemplated according to embodiments of the inventive concept.

[0068] FIG. 4 is a flow diagram 400 depicting a simplified example method for recycling slurry in a CMP tool, according to one or more embodiments of the inventive concept. Referring to FIG. 4, the method 400 is configured to collect slurry from at least one CMP tool in step 402. The collected slurry is provided to a vessel (e.g., the slurry recycle vessel(s) 210 in FIGS. 2B and 2C) in step 404. As described in connection with FIG. 2B, the slurry may be collected in anAttorney Docket No. 5308.3543.WOintermediate stage CMP processing window of a CMP processing cycle during which the slurry has a lower likelihood of being diluted and / or contaminated, for example by cleaning chemistry.

[0069] In step 406, the received slurry in the vessel is refreshed (i.e., reconditioned).Specifically, one or more properties of the slurry in the vessel may be monitored and, when at least one property being monitored is outside of a prescribed threshold or range, certain actions may be taken to refresh the slurry. Refreshing the slurry in step 406 may involve, for example, adding fresh slurry to the slurry in the vessel, adding an acid solution to the slurry (e.g., if the measured pH is too high, as is often the case for SiC CMP slurries), adding a base solution to the slurry (e.g., if the measured pH is too low), adding a buffer to stabilize pH, adding ions to maintain ionic strength (conductivity), adding stabilizing chemistries to control slurry degradation (e.g., to control degradation of permanganate, add periodate, persulfate, etc.), etc. The refreshed slurry is then provided to the CMP tool in step 408.

[0070] FIGS. 5A and 5B are flow diagrams depicting at least a portion of an example method 500 for recycling slurry in a CMP tool, according to one or more embodiments of the inventive concept. The method 500 may be a more detailed implementation of the simplified example method 400 shown in FIG. 4. Referring to FIGS. 5A and 5B, the method 500 includes initializing the CMP tool in step 502. Initialization may involve, for example, providing a polishing pad on the platen of the CMP tool and chucking the wafer on a carrier to begin a CMP processing cycle. Slurry is introduced to the CMP tool and CMP processing proceeds in step 504. During this initial stage in the CMP processing, before intermediate stage CMP processing has begun, the method is configured to prevent collection of slurry.

[0071] Slurry collected during certain stages of the CMP processing cycle will have a higher likelihood of being contaminated, such as by cleaning solutions (i.e., cleaning chemistry) or DIW, among other contaminants. As previously explained, it is preferable to avoid slurry collection during an initial start-up period (e.g., the first 30 seconds or so) of the CMP processing cycle where there is a likelihood that cleaning materials may be present after processing a prior wafer, and during an end period during which the polishing pad is being cleaned and reconditioned (e.g., the last minute or so of the CMP processing cycle). There is a lower likelihood of slurry dilution and / or contamination during this intermediate stage CMP processingAttorney Docket No. 5308.3543.WOwindow, where CMP polishing has already started and before the wafer has been de-chucked from the CMP tool and pad cleaning has begun.

[0072] In step 506, the method 500 determines whether the CMP tool is in the intermediate stage CMP processing window of the CMP processing cycle. When it is determined in step 506 that the CMP processing cycle is outside of the intermediate stage CMP processing window, the method 500 is configured to discard collected slurry in step 508, such as by directing the slurry to a drain of the CMP tool, or otherwise prevent the CMP tool from collecting slurry. When it is determined in step 506 that the CMP tool is within the intermediate stage CMP processing window, the method 500 is configured to divert the collected slurry in step 510 (e.g., using the slurry diversion mechanism 204 shown in FIG. 2B). Optionally, the method 500 may filter the slurry in step 511, such as by providing the slurry to a first filter (e.g., first filter 206 in FIG. 2B). The first filter may be configured to remove, for example, large suspended particles and / or agglomerates, polishing pad debris, and CMP by-products in the slurry that are greater than a first prescribed size (e.g., about 50 - 100 pm). Particles of this first prescribed size may be considered coarse particles, larger than a size of the abrasive contained in fresh (i.e., unused) slurry.

[0073] The slurry diverted in step 510 may be provided to a slurry recycle vessel or reservoir (e.g., slurry recycle vessel 210 in FIG. 2B) in step 512. The received slurry may be held in the vessel until the method 500 determines that it is ready to be introduced back to the CMP tool. In some embodiments, the slurry recycle vessel may be configured to recirculate or mix the slurry so that the abrasive remains suspended in solution. One or more properties of the slurry are monitored in step 514, for example using inline metrologies (e.g., inline monitor 212 in FIG. 2B) configured to measure key properties of the slurry while the slurry is held in the slurry recycle vessel. As previously described, properties of the slurry that may be monitored include, for example, pH, particle size, slurry reactivity (redox potential and conductivity), solution / abrasive concentration, and / or density, although embodiments are not limited thereto.

[0074] In step 516, the method 500 is configured to determine whether or not the property(ies) being monitored are outside of a prescribed threshold or range. For example, a pH sensor may be employed in step 516 to determine whether the slurry is within a prescribed range of pH values. Likewise, a large particle counter or other particle sensor may be employed in step 516Attorney Docket No. 5308.3543.WOto determine whether a size of suspended particles in the slurry is less than a prescribed value or range. When the property(ies) of the slurry being monitored falls outside of the prescribed threshold or range, step 518 determines whether the slurry can be refreshed to its original condition.

[0075] If it is determined in step 518 that the slurry can be refreshed, the method 500 may take certain actions to refresh the slurry in step 520. Such actions may include, but are not limited to, adding fresh slurry to the slurry recycle vessel, adding an acid solution to the slurry (e.g., if the measured pH is too high, as is often the case for SiC CMP slurries), adding a base solution to the slurry (e.g., if the measured pH is too low), adding a buffer to stabilize pH, adding ions to maintain ionic strength (conductivity), adding stabilizing chemistries to control slurry degradation (e.g., to control degradation of permanganate, add periodate, persulfate, etc.), etc. The method 500 then returns to step 514 where one or more parameters of the slurry are monitored to determine whether the condition of the refreshed slurry has improved. If it is determined in step 518 that the slurry cannot be refreshed (e.g., permanganate in the slurry has been fully consumed), the slurry is discarded in step 522. At that point, fresh slurry is introduced to the CMP tool in step 524 and the CMP processing cycle continues in step 504 until the wafer has completed CMP.

[0076] When it is determined in step 516 that the property(ies) of the slurry being monitored has not exceeded the prescribed threshold or range, the method 500 is configured to optionally filter the slurry in step 526, such as by providing the slurry to a second filter (e.g., second filter 220 in FIG. 2B). The second filter may be configured to remove suspended particles in the collected slurry that are greater than a second prescribed size (e.g., about 1 pm - 5 pm). Particles of this second prescribed size may be considered fine particles, smaller in size than particles remaining in the slurry after passing through the first filtering step 510. After passing through the second filtering step 526, of if filtering is not performed, the recycled (i.e., refreshed) slurry is provided to the CMP tool in step 528, and CMP processing continues at step 504 until the wafer has completed CMP. In this manner, the slurry recycling method 500 is configured to maintain the quality of the recycled slurry at or near the quality of fresh (i.e., unused) slurry thereby saving significant cost in CMP processing, particularly for signal-wafer CMP tools adapted to process 150 mm or greater SiC wafers.Attorney Docket No. 5308.3543.WO

[0077] Illustrative CMP slurry recycling systems (e.g., 200 and 250 shown in FIGS. 2A, 2B and 2C, respectively) and illustrative CMP slurry recycling methods (e.g., 400 and 500 shown in FIGS. 4, 5 A and 5B) have been described herein by way of example only and without limitation or loss of generality. Depending on the embodiment, an initial vessel or container is provided where the slurry is maintained and one or more properties of the slurry are measured to determine if the slurry can be recycled. When the slurry cannot be recycled, it is discarded (e.g., drained). When the slurry can be recycled, it is transferred to a recycling vessel for refreshing and / or measurement of its properties. The measuring of slurry properties and reconditioning or refreshing of the slurry can be done in a single vessel, in parallel with multiple vessels, in serial vessels and / or in an inline vessel used for transport, monitoring and / or recycling of the slurry, where measuring or monitoring of the same or different properties of the slurry are measured and / or refreshed in progressive or incremental stages. With particular reference, for example, to the loop including steps 514 and 516, the monitoring or measuring and / or refreshing or reconditioning of the slurry properties can be done in multiple vessels in parallel and / or in series where monitoring and / or reconditioning or refreshing of the slurry is done in progressive or incremental steps for one or more measured properties together or separately, and the loop happens as the slurry passes through multiple measuring and refreshing steps.

[0078] It is contemplated that any of the foregoing aspects, and / or various separate aspects and features as described herein, may be combined for additional advantage. Any of the various embodiments as disclosed herein may be combined with one or more other disclosed embodiments unless indicated to the contrary herein.

[0079] It will be understood that although ordinal terms, such as first, second, etc., may be used herein to describe various elements and / or process steps, these elements and / or steps should not be limited by such terms. These terms are merely used to distinguish one element and / or step from another and may not necessarily be used to convey any particular order of the elements and / or steps unless expressly noted. For example, a first element could be termed a second element and similarly, a second element could be termed a first element, without departing from the scope of the present disclosure.

[0080] Techniques and / or tooling used in fabricating semiconductor devices will already be familiar to those having ordinary skill in the relevant art. Moreover, many of the processing steps and tooling used to fabricate semiconductor devices in general are described in a number ofAttorney Docket No. 5308.3543.WOreadily available publications, including, for example: P H. Holloway et al., Handbook of Compound Semiconductors: Growth, Processing, Characterization, and Devices, Cambridge University Press, 2008; and R.K. Willardson et al., Processing and Properties of Compound Semiconductors, Academic Press, 2001, which are incorporated by reference herein in their entirety.

[0081] It will be understood that when an element such as a layer, region, or structure is referred to as being “on” or extending “onto” another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” or extending “directly onto” another element, there are no intervening elements present. Likewise, it will be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. It will also be understood that when an element such as a layer, region, or structure is referred to as being “over” or extending “over” another element, it can be directly over or extend directly over the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly over” or extending “directly over” another element, there are no intervening elements present.

[0082] Relative terms such as “below,” “above,” “upper,” “lower,” “top,” “bottom,” “under,” “over,” “horizontal,” “vertical,” etc., as may be used herein, are intended to describe a spatial relationship of one element, layer, or region to another element, layer, or region as illustrated in the figures, rather than an absolute position of the element, layer, or region. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the figures.

[0083] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes,” and / or “including” when used herein specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition ofAttorney Docket No. 5308.3543.WOone or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0084] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0085] Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Claims

Attorney Docket No. 5308.3543.WOCLAIMSWhat is claimed is:

1. A slurry recycling system, comprising:a slurry diversion mechanism configured to receive slurry from at least one chemicalmechanical polishing (CMP) tool;a vessel configured to receive slurry diverted from the at least one CMP tool for reconditioning of the slurry; anda slurry redistribution mechanism to provide reconditioned slurry to the at least one CMP tool.

2. The slurry recycling system of claim 1, wherein the slurry diversion mechanism comprises a valve configured to selectively open during a prescribed stage of a CMP processing cycle for providing received slurry to the vessel.

3. The slurry recycling system of claim 2, wherein the valve is configured to open during an intermediate stage of the CMP processing cycle and to close when the at least one CMP tool is operating outside of the intermediate stage of the CMP processing cycle.

4. The slurry recycling system of claim 1, wherein the slurry diversion mechanism comprises a valve configured to control a flow rate of received slurry provided to the vessel.

5. The slurry recycling system of claim 1, further comprising at least one sensor configured to monitor one or more characteristics of the slurry in the vessel.

6. The slurry recycling system of claim 5, wherein the slurry redistribution mechanism is further configured to refresh the slurry when the one or more characteristics of the slurry is outside a prescribed threshold.

7. The slurry recycling system of claim 6, wherein the slurry redistribution mechanism is further configured to refresh the slurry by performing additive reconditioning of the slurry in the vessel.Attorney Docket No. 5308.3543.WO8. The slurry recycling system of claim 1, wherein the slurry redistribution mechanism is further configured to refresh the slurry by performing at least one of additive reconditioning or subtractive reconditioning of the slurry in the vessel.

9. The slurry recycling system of claim 8, wherein additive reconditioning comprises changing at least one of a pH value of the slurry, a reduction-oxidation (redox) potential of the slurry, or a conductivity of the slurry.

10. The slurry recycling system of claim 8, wherein subtractive reconditioning comprises removing suspended particles in the slurry greater than a prescribed size.

11. The slurry recycling system of claim 1, wherein the slurry redistribution mechanism comprises at least one of a gravity feed line or a vacuum line coupled between the vessel and the at least one CMP tool.

12. The slurry recycling system of claim 1, wherein the at least one CMP tool is a silicon carbide (SiC) CMP tool.

13. An apparatus for recycling slurry, comprising:a vessel configured to receive slurry collected from at least one chemical-mechanical polishing (CMP) tool;at least one sensor configured to monitor one or more characteristics of the slurry held in the vessel; anda controller configured to receive information provided by the at least one sensor regarding the one or more characteristics of the slurry.

14. The apparatus of claim 13, further comprising a first filter configured to remove suspended particles in the slurry that exceed a first prescribed size to provide a first filtered slurry.Attorney Docket No. 5308.3543.WO15. The apparatus of claim 14, wherein the controller is further configured to refresh the slurry when the one or more characteristics of the slurry is outside a prescribed threshold, and to provide the first filtered slurry to the at least one CMP tool when the one or more characteristics of the slurry are within the prescribed threshold.

16. The apparatus of claim 13, further comprising a diverter valve between the at least one CMP tool and the vessel, the diverter valve configured to discard the slurry collected from the at least one CMP tool when the CMP tool is operating outside of a first CMP processing window, and to provide the slurry collected from the at least one CMP tool to the vessel when the CMP tool is operating within the first CMP processing window.

17. The apparatus of claim 13, wherein the apparatus is configured to collect the slurry from the at least one CMP tool during a first CMP processing window and to provide the collected slurry to the vessel.

18. The apparatus of claim 14, further comprising a second filter between the at least one CMP tool and the vessel, the second filter configured to remove suspended particles in the slurry collected from the at least one CMP tool during a first CMP processing window that exceed a second prescribed size, the second prescribed size being larger than the first prescribed size.

19. The apparatus of claim 14, further comprising a slurry redistribution mechanism coupled to an output of the vessel, the slurry redistribution mechanism configured to direct the slurry in the vessel through the first filter and to the at least one CMP tool.

20. The apparatus of claim 13, wherein the controller and the at least one sensor are configured to form a closed loop feedback system with the vessel.

21. The apparatus of claim 13, wherein the at least one sensor comprises at least one of a pH sensor configured to monitor a pH value of the slurry, a reduction-oxidation potential and conductivity sensor configured to monitor reactivity of the slurry, a spectrophotometric sensor configured to monitor solution / abrasive concentration of the slurry, a density sensor to monitorAttorney Docket No. 5308.3543.WOsolid content in the slurry, or a particle counter configured to monitor a size of suspended particles in the slurry.

22. The apparatus of claim 13, wherein the controller is configured to cause the slurry in the vessel to be discarded when, based at least in part on the information provided by the at least one sensor, it is determined that the slurry cannot be refreshed.

23. The apparatus of claim 13, further comprising a slurry collection tray operatively coupled to the at least one CMP tool, the slurry collection tray configured to receive slurry from a platen of the at least one CMP tool during a first CMP processing window and to prevent collection of the slurry from the at least one CMP tool when the CMP tool is operating outside of the first CMP processing window.

24. The apparatus of claim 23, wherein the slurry collection tray comprises:a base;a front wall;a back wall in contact with the platen of the at least one CMP tool; andtwo side walls,wherein each of the front wall, the back wall, and the two side walls extends vertically upward from the base to define an interior space within the slurry collection tray where collected slurry from the platen of the CMP tool is received.

25. The apparatus of claim 24, wherein the base of the slurry collection tray comprises an opening for allowing slurry collected from the at least one CMP tool to exit through the opening.

26. The apparatus of claim 24, wherein the slurry collection tray further comprises a cover provided over at least a portion of the slurry collection tray, the cover supported by an upper rim defined by a top edge of each of the front wall, the back wall and / or the two side walls, the cover configured to reduce contaminants introduced into the slurry collected from the at least one CMP tool.Attorney Docket No. 5308.3543.WO27. The apparatus of claim 17, wherein the first CMP processing window is an intermediate stage CMP processing window that excludes an initial start-up period of CMP processing and an end cleaning period of the CMP processing.

28. The apparatus of claim 13, wherein the vessel is configured to mix the slurry to prevent suspended particles in the slurry from falling out of suspension.

29. The apparatus of claim 25, wherein the base of the slurry collection tray is tapered downward from the back wall to the front wall for allowing slurry collected from the at least one CMP tool to exit through the opening.

30. An apparatus for recycling slurry, comprising:a vessel configured to receive slurry collected from at least one chemical-mechanical polishing (CMP) tool; anda controller configured to selectively divert slurry collected from the at least one CMP tool to the vessel.

31. The apparatus of claim 30, further comprising a diverter coupled between the at least one CMP tool, the vessel and a drain.

32. The apparatus of claim 30, wherein the controller is configured to provide the slurry collected from the at least one CMP tool to the vessel during an intermediate stage CMP processing window that excludes an initial start-up period of CMP processing and an end cleaning period of the CMP processing.

33. A slurry collection apparatus, comprising:a base; anda sidewall extending upward from the base to define an interior space within the slurry collection apparatus where collected slurry from a chemical-mechanical polishing (CMP) tool is received,Attorney Docket No. 5308.3543.WOwherein the slurry collection apparatus is movably coupled to the CMP tool and configured to be manually and / or automatically engaged / disengaged with the CMP tool for controlling collection of slurry from the CMP tool.

34. The slurry collection apparatus of claim 33, wherein the interior space defined by the sidewall is circular in shape when viewed in plan view.

35. The slurry collection apparatus of claim 33, wherein the interior space defined by the sidewall is trapezoidal in shape when viewed in plan view.

36. The slurry collection apparatus of claim 33, further comprising an opening in the base for releasing the collected slurry from the slurry collection apparatus.

37. The slurry collection apparatus of claim 36, wherein the base is inclined to direct the collected slurry from the CMP tool toward the opening.

38. The slurry collection apparatus of claim 36, wherein the sidewall is inclined to direct the collected slurry from the CMP tool toward the opening.

39. The slurry collection apparatus of claim 33, further comprising an attachment structure affixed to the sidewall, the attachment structure configured for movable attachment of the slurry collection apparatus to the CMP tool for enabling the slurry collection apparatus to be manually and / or automatically engaged / disengaged from collecting slurry.

40. The slurry collection apparatus of claim 33, wherein the slurry collection apparatus is configured to be engaged with the CMP tool for receiving slurry from the CMP tool during a first CMP processing window, and to be disengaged from the CMP tool for preventing collection of the slurry from the CMP tool when the CMP tool is operating outside of the first CMP processing window.Attorney Docket No. 5308.3543.WO41. The slurry collection apparatus of claim 33, further comprising a cover supported by an upper edge of the sidewall, the cover configured to reduce contaminants introduced into the slurry collected from the CMP tool.

42. A method for recycling slurry, the method comprising:determining whether a chemical-mechanical polishing (CMP) tool is in an intermediate stage CMP processing window of operation;discarding the slurry when the CMP tool is operating outside of the intermediate stage CMP processing window; andproviding the slurry collected from the CMP tool to a vessel for refreshing the slurry.

43. A method for recycling slurry, the method comprising:collecting slurry from at least one chemical-mechanical polishing (CMP) tool; providing the collected slurry to a vessel;refreshing the slurry in the vessel; andproviding the refreshed slurry from the vessel to the at least one CMP tool.

44. The method of claim 43, further comprising monitoring one or more properties of the slurry in the vessel to determine whether the one or more properties of the slurry are outside of a prescribed threshold.

45. The method of claim 43, wherein refreshing the slurry comprises performing additive reconditioning of the slurry in the vessel.

46. The method of claim 43, wherein refreshing the slurry comprises performing at least one of additive reconditioning or subtractive reconditioning of the slurry in the vessel.

47. A chemical-mechanical polishing (CMP) tool with an integrated slurry collection apparatus, said slurry collection apparatus comprising:a slurry collector configured to block slurry when at least a portion of the slurry collector is in a first position, andAttorney Docket No. 5308.3543.WOthe slurry collector receives slurry when at least the portion of the slurry collector is in a second position.

48. The CMP tool of claim 47, wherein the slurry collector comprises an input and an output, the input being positioned higher than the output.

49. The CMP tool of claim 47, wherein the slurry collector comprises an input and an output, wherein at least one of the input or the output is blocked by at least the portion of the slurry collector in a first position and is open when at least a portion of the slurry collector is in a second position.

50. The CMP tool of claim 49, wherein the portion of the slurry collector comprises a blocking element that is engaged in the first position and disengaged in the second position.

51. The CMP tool of claim 49, wherein at least the portion of the slurry collector comprises at least one valve at at least one of the input or the output of the slurry collector.

52. The CMP tool of claim 47, wherein the slurry collector comprises an input to receive slurry, and the slurry collector comprises a sloped surface.

53. The CMP tool of claim 49, wherein at least the portion of the slurry collector that moves from the first position to the second position comprises a blocking member to open and block the input.

54. The CMP tool of claim 47, wherein the slurry collector is in the first position when the CMP tool is operating in an intermediate stage processing window and is in the second position when the CMP tool is operating outside of the intermediate stage processing window.

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