Chemical mechanical polishing slurry build-up monitoring

Abstract

An apparatus and method for monitoring slurry build-up are disclosed. A substrate polishing apparatus includes a surface at least partially coated with a fluorescent material, a light source configured to illuminate the surface, an image sensor configured to image the surface, and a processor coupled to the image sensor and configured to monitor slurry build-up on the surface using data supplied from the image sensor.

Description

Technical Field

[0001] The embodiments of this disclosure generally relate to chemical mechanical polishing (CMP) systems for manufacturing semiconductor devices. Specifically, the embodiments herein relate to monitoring slurry buildup in a CMP system. Background Technology

[0002] Chemical mechanical polishing (CMP) is commonly used in semiconductor device manufacturing to planarize or polish material layers deposited on substrate surfaces. During a CMP process, the substrate is held in a substrate carrier, which, in the presence of a polishing slurry, presses the back side of the substrate against a rotating polishing pad. Material is removed from the surface of the substrate material layer in contact with the polishing pad through a combination of the chemical and mechanical activity provided by the polishing slurry and the relative motion between the substrate and the polishing pad.

[0003] Polishing slurries used in CMP processes can include aqueous solutions of one or more chemical components and nanoscale abrasive particles suspended in the aqueous solution. Typically, during polishing, dried residues of the polishing slurry, such as abrasive agglomerates, accumulate on the surfaces of components positioned above or otherwise close to the polishing pad. For example, dried residues of the polishing slurry tend to accumulate on the surfaces of CMP system components (such as substrate carriers, pad conditioner assemblies, and / or fluid delivery arms) positioned on the polishing pad when the polishing slurry is applied. If these accumulated residues are not removed, the abrasive agglomerates may detach from the component surfaces onto the polishing pad and cause undesirable damage to the material surface of the substrate subsequently polished on the pad. This damage often manifests as scratches on the substrate surface, such as microscratches, which can adversely affect the performance of devices formed on the substrate surface, or in some cases, render the device inoperable.

[0004] Unfortunately, removing accumulated residue from component surfaces is often laborious and time-consuming, as agglomerated abrasive grains tend to form a cement-like layer. The result is undesirable, prolonged, and frequent downtime of the polishing system for consumable replacements and / or preventative maintenance procedures, in which the accumulated residue is manually removed from the component surfaces.

[0005] Therefore, there is a need in the art for apparatus and methods to solve the above problems. Summary of the Invention

[0006] This disclosure generally relates to chemical mechanical polishing (CMP) systems used in semiconductor device manufacturing. Specifically, embodiments herein relate to monitoring slurry buildup in CMP systems.

[0007] In one embodiment, a substrate polishing apparatus includes: a surface at least partially coated with a fluorescent material, a light source configured to illuminate the surface, an image sensor configured to image the surface, and a processor coupled to the image sensor and configured to monitor slurry buildup on the surface using data supplied from the image sensor.

[0008] In another embodiment, a slurry buildup monitoring method includes capturing an image of a surface of a polishing apparatus. The surface is at least partially coated with a fluorescent material. The method includes selecting a region of interest (ROI) in the image and determining a fluorescence parameter for the ROI, wherein the value of the fluorescence parameter corresponds to the amount of slurry buildup on the ROI.

[0009] In yet another embodiment, a substrate polishing apparatus includes: a surface at least partially coated with a fluorescent material, a light source configured to illuminate the surface, a sensor configured to measure the fluorescence intensity of a region of interest on the surface, and a non-transitory computer-readable medium storing instructions thereon for a monitoring method. The monitoring method includes polishing a substrate with a slurry in the substrate polishing apparatus. Accumulation of slurry on the surface reduces the measurable fluorescence intensity of the region of interest. The method includes turning on the light source and, while the light source is turned on, using the sensor to measure the fluorescence intensity of the region of interest. The method includes comparing the measured fluorescence intensity to a first range, and creating an alarm if the measured fluorescence intensity is outside the first range. Attached Figure Description

[0010] To gain a detailed understanding of the features described above, reference can be made to the embodiments for a more specific description of the present disclosure, some of which are illustrated in the accompanying drawings. However, it should be noted that the drawings illustrate only typical embodiments of the present disclosure and should not be considered as limiting its scope, as the present disclosure may allow for other equally effective embodiments.

[0011] Figure 1A This is a plan view of a polishing apparatus according to one or more embodiments.

[0012] Figure 1B yes Figure 1A A schematic partial cross-sectional side view.

[0013] Figure 1C yes Figure 1A A schematic partial cross-sectional side view.

[0014] Figure 2 This is a diagram illustrating a method for monitoring slurry buildup according to one or more embodiments.

[0015] Figure 3This is a schematic diagram illustrating an exemplary setup for monitoring slurry buildup on a surface according to one or more embodiments. Detailed Implementation

[0016] The embodiments of this disclosure generally relate to chemical mechanical polishing (CMP) systems for manufacturing semiconductor devices. Specifically, the embodiments herein relate to monitoring slurry buildup in a CMP system.

[0017] The apparatus and / or methods disclosed herein provide for the monitoring of slurry buildup on the inner surface of a CMP tool. During conventional CMP processes where slurry buildup is unmonitored, defects resulting from slurry residue falling onto the wafer surface may be the earliest and possibly only indication that cleaning is required. Therefore, when a defect potentially attributable to slurry buildup is detected, the tool may be taken offline for cleaning or scheduled for cleaning, even if cleaning was not pre-planned. Scheduling cleaning in this way (i.e., based on observations of defects caused by the CMP process) is inefficient, leading to wafer scrap and reduced overall process yield. In contrast, the apparatus and / or methods disclosed herein facilitate scheduling cleaning solely based on slurry buildup (e.g., before slurry buildup causes defects). Scheduling cleaning solely based on slurry buildup results in more efficient scheduling, increased overall process yield, and reduced or prevented occurrence of defects that may result from a lack of cleaning.

[0018] In some alternative CMP processes, to prevent defects that may be attributable to slurry buildup, CMP tools can be taken offline for cleaning at pre-scheduled time intervals, regardless of actual slurry buildup. However, this approach can also reduce overall process throughput by performing tool cleaning before it is actually needed. In contrast, using the apparatus and / or methods disclosed herein, cleaning is scheduled only when required, resulting in more efficient cleaning scheduling with less tool downtime.

[0019] The apparatus and / or methods disclosed herein provide for monitoring slurry buildup to target cleaning only specific areas of the CMP tool, as opposed to conventional methods that clean various internal surfaces without considering actual slurry buildup. Therefore, the apparatus and / or methods disclosed herein offer more efficient cleaning of selected surfaces with less tool downtime. Furthermore, by prioritizing the surfaces most in need of cleaning, the cleaning process can be optimized for greater efficiency. The apparatus and / or methods disclosed herein also provide for monitoring slurry buildup to help identify problem areas for future continuous improvement of the procedure.

[0020] Figure 1AThis is a plan view of a polishing apparatus 100 (such as a chemical mechanical polishing (CMP) tool for processing one or more substrates). The polishing apparatus 100 includes a polishing platform or substrate 102 that at least partially supports and accommodates a plurality of polishing stations 124. For example, the polishing apparatus 100 shown includes four polishing stations 124a, 124b, 124c, and 124d. Each polishing station 124 is adapted to polish a substrate held in a carrier head 126.

[0021] The polishing apparatus 100 also includes a plurality of carrier heads 126, each of which is configured to carry a substrate. The number of carrier heads can be equal to or greater than the number of polishing stations, such as four or six carrier heads. For example, the number of carrier heads can be two more than the number of polishing stations. This allows the substrate to be processed to be loaded and unloaded from two of the carrier heads while polishing is performed at the remaining parts of the polishing station with the other carrier heads, thereby providing increased throughput.

[0022] The polishing apparatus 100 also includes a transfer station 122 for loading and unloading substrates from carrier heads 126. The transfer station 122 may include a plurality of loading cups 123, such as two loading cups 123a and 123b, adapted to facilitate the transfer of substrates between carrier heads 126 and a factory interface (not shown) or other equipment (not shown) via a transfer robot 110. The loading cups 123 generally facilitate transfer between the robot 110 and each of the carrier heads 126.

[0023] The stations of the polishing apparatus 100, including the transfer station 122 and the polishing station 124, can be positioned at substantially equal angular intervals around the center of the substrate 102. This is not necessary, but it can provide a reduced footprint for the polishing apparatus 100.

[0024] Each polishing station 124 includes a polishing pad 130 supported on a worktable 120 (e.g., ...). Figures 1B to 1C (As shown). For the polishing operation, a carrier head 126 is positioned at each polishing station 124. Two additional carrier heads may be positioned in a transfer station 122 to exchange polished substrates for unpolished substrates while other substrates are being polished at polishing station 124.

[0025] The carrier head 126 is adapted to hold the substrate against the polishing surface of the polishing pad 130 while providing relative motion between the carrier head 126 and the stage 120 to polish the substrate. The relative motion can be rotational, lateral, or some combination thereof, and is provided by at least one of the carrier head 126 and the stage 120. Each carrier head 126 may have independent control over polishing parameters (e.g., pressure) associated with each respective substrate.

[0026] The carrier head 126 is supported by a support structure that allows each carrier head to move along a path sequentially passing through the first polishing station 124a, the second polishing station 124b, the third polishing station 124c, and the fourth polishing station 124d. This allows each carrier head to be selectively positioned on each of the polishing stations 124 and the loading cup 123.

[0027] In some embodiments, each carrier head 126 is coupled to a bracket 108 mounted on an overhead track 128. By moving the bracket 108 along the overhead track 128, the corresponding carrier head 126 can be positioned above a selected polishing station 124 or loading cup 123. The carrier head 126 moving along the overhead track 128 traverses a path through each of the polishing stations 124.

[0028] exist Figure 1A In the illustrated embodiment, the overhead track 128 has a circular configuration (shown in dashed lines) that allows the carrier 108 holding the bearing head 126 to selectively run over and / or leave the loading cup 123 and polishing station 124. The overhead track 128 may have other configurations, including elliptical, oval, straight, or other suitable orientations. Alternatively, in some embodiments (not shown), the bearing head 126 is suspended from a rotating rack, and rotation of the rotating rack causes all bearing heads 126 to move simultaneously along a circular path. Although the polishing apparatus shown herein is equipped with an overhead track, this disclosure can utilize any suitable polishing apparatus. In one example, the polishing apparatus may have a robot that provides the same functionality as the overhead track.

[0029] Each polishing station 124 of the polishing apparatus 100 includes a spray bar 134 for dispensing polishing fluid (such as abrasive slurry) onto a polishing pad 130, such as... Figure 1B As shown in more detail below. Each polishing station 124 of the polishing apparatus 100 includes a pad adjustment device 112 for grinding the polishing surface 131 of the polishing pad 130 to maintain the polishing pad 130 in a consistent grinding state, such as... Figure 1C See below for more details.

[0030] A controller 190 (such as a programmable computer) is connected to the respective motors to independently control the rotational rates of the worktable 120 and the carrier head 126, as described in more detail below. For example, each motor may include an encoder that measures the angular position or rotational rate of the associated drive shaft. Similarly, the controller 190 is connected to an actuator in each bracket 108 to independently control the lateral movement of each carrier head 126. For example, each actuator may include a linear encoder that measures the position of the bracket 108 along the overhead track 128.

[0031] The controller 190 includes a programmable central processing unit (CPU) 192, which can operate together with a memory 194 (e.g., non-volatile memory) and support circuitry 196. The support circuitry 196 is conventionally coupled to the CPU 192 and includes caches, clock circuitry, input / output subsystems, power supplies, and combinations thereof, which are coupled to various components of the polishing apparatus 100.

[0032] In some embodiments, CPU 192 is one of any form of general-purpose computer processor used in an industrial environment, such as a programmable logic controller (PLC), for controlling various monitoring system components and subprocessors. Memory 194 coupled to CPU 192 is non-transitory and is typically one or more of readily available memory such as random access memory (RAM), read-only memory (ROM), floppy disk drive, hard disk, or any other form of local or remote digital storage device.

[0033] In this document, memory 194 is in the form of a computer-readable storage medium (e.g., non-volatile memory) containing instructions that, when executed by CPU 192, facilitate the operation of polishing apparatus 100. The instructions in memory 194 are in the form of a program product, such as a program implementing the methods of this disclosure (e.g., a middleware application, an equipment software application, etc.). The program code may conform to any of a variety of different programming languages. In one example, this disclosure may be implemented as a program product stored on a computer-readable storage medium for use with a computer system. The program(s) of the program product define the functionality of the various embodiments (including those described herein).

[0034] Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media that permanently store information thereon (e.g., read-only memory devices within a computer, such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips, or any type of solid-state non-volatile semiconductor memory); and (ii) writable storage media that store variable information thereon (e.g., floppy disks in a disk drive or hard disk drive, or any type of solid-state random access semiconductor memory). Such computer-readable storage media are embodiments of this disclosure when carrying computer-readable instructions that instruct the functions described herein.

[0035] Although illustrated as a single computer, controller 190 can be a distributed system, such as comprising multiple independently operating processors and memory. The computer architecture can be adapted for programming controller 190 to perform various polishing operations, controlling the order and timing of the carrier head's positioning at the polishing station.

[0036] For example, one operating mode involves the controller loading the substrate into a carrier head 126 at one of the loading cups 123, and sequentially positioning the carrier head 126 at each polishing station 124a, 124b, 124c, and 124d, such that the substrate is polished sequentially at each polishing station. After polishing at the last station, the carrier head 126 is returned to one of the loading cups 123, and the substrate is removed from the carrier head 126.

[0037] Figure 1B yes Figure 1A A schematic partial cross-sectional side view illustrates an exemplary spray bar 134 combined with polishing station 124. Polishing apparatus 100 has a housing 101. Housing 101 generally includes a base 102, an upper wall 103, and a sidewall 104 between the base 102 and the upper wall 103. The base 102, upper wall 103, and sidewall 104 define a processing area 105 of polishing apparatus 100.

[0038] The carrier head 126 has a housing 129. The carrier head 126 is coupled to an overhead track 128, which is coupled to a column 162 and extends over a worktable 120. A drive system 106 is coupled to the carrier head 126 via a drive shaft 107. The drive system 106 provides at least rotational motion to the carrier head 126. The drive system 106 can also provide lateral motion to the carrier head 126 to apply a sweeping motion relative to the worktable 120, for example, by driving a bracket 108 on the overhead track 128. The carrier head 126 can be actuated toward and away from the worktable 120 such that a substrate 114 held in the carrier head 126 can be positioned against a polishing pad 130 during polishing.

[0039] The worktable 120 at each polishing station 124 is rotatable about axis 121. For example, a motor 160 rotates drive shaft 125 to rotate the worktable 120. The worktable 120 is rotatably mounted on the substrate 102. A bearing 158 is disposed between the worktable 120 and the substrate 102 to facilitate rotation of the worktable 120 relative to the substrate 102.

[0040] During operation, the worktable 120 rotates about axis 121, and each bearing head 126 rotates about a corresponding axis 127 and translates laterally across the polishing surface 131. The lateral sweep is in a direction parallel to the polishing surface 131. The lateral sweep can be a linear or arcing motion.

[0041] Each spray bar 134 delivers polishing fluid (such as slurry 135) to an associated polishing pad 130 to facilitate substrate polishing operations. Additionally, the spray bar 134 can deliver cleaning fluid (e.g., deionized water) to the polishing pad 130 to wash away polishing byproducts from the polished surface 131. Figure 1BAs shown, the spray bar 134 includes an arm 136 with multiple fluid dispensing ports (not shown) at its distal end for spraying fluids (such as slurry 135) onto the polishing surface 131. The proximal end of the arm 136 is coupled to a base 138 extending upward from the base 102 of the housing 101. The base 138 is rotatable to a first position disposed on the worktable 120 (e.g., Figure 1B (As shown) and a second position, pivoting arm 136 is positioned adjacent to the worktable 120. During polishing, the spray bar 134 is in the first position, and as the worktable 120 rotates, slurry 135 is applied to the polishing surface 131.

[0042] The spray bar 134 is fluidly coupled to one or more fluid sources outside the processing area 105, such as slurry source 140 and deionized water source 142. Although only slurry source and deionized water source are illustrated, the spray bar 134 can utilize a variety of additional fluid chemicals known in the art. Other suitable fluid chemicals may include alcohols, amphiphilic compounds (e.g., detergents, soaps, lipoproteins, surfactants, synthetic amphiphiles, naturally occurring amphiphiles), acids (e.g., citric acid, hydrogen peroxide), bases, oxidizing agents, reducing agents, hydrophilic compounds, hydrophobic compounds (e.g., oils, fats, waxes), or mixtures thereof.

[0043] Figure 1C yes Figure 1A A schematic partial cross-sectional side view illustrating an exemplary pad adjustment device 112 combined with polishing station 124. Figure 1C The sectional view is from the Figure 1B Different angles, for example, cut at approximately 90-degree intervals. Each pad adjustment device 112 includes an arm 113 that supports an adjuster head 115 on a corresponding worktable 120. The arm 113 is rotatably secured to a base 102. The distal end of the arm 113 is coupled to a housing 116 of the adjuster head 115. A motor 117 is coupled to the distal end of the arm 113 for rotating the adjuster head 115 during pad adjustment. The proximal end of the arm 113 is coupled to a base 118 extending upward from the base 102 of the housing 101. The base 118 is rotatable to pivot the arm 113 and laterally translate the adjuster head 115 across a polished surface 131.

[0044] Each polishing station 124 of the polishing apparatus 100 includes a station cup 146 radially surrounding the worktable 120. The station cup 146 has an inner sidewall surface 147 facing the worktable 120. The inner sidewall surface 147 extends over the polishing surface 131. Slurry 135 from the polishing pad 130 contacts the inner sidewall surface 147 and is collected inside the station cup 146. A discharge port 148 at the bottom of the station cup 146 and / or through the base 102 is used to discharge the slurry 135 collected within the station cup 146.

[0045] During operation, slurry 135 may accumulate on surfaces within housing 101 due to accidental splashing, spraying, and / or atomization. For example, slurry 135 may accumulate on the surface of the support head 126, structures above the support head 126 (such as overhead track 128, spray bar 134, sidewall 104, stand cup 146, or pad adjustment device 112). To facilitate monitoring of slurry 135 accumulation, one or more surfaces are at least partially coated with a fluorescent material. When the fluorescent material coating is used with a non-fluorescent slurry, fluorescence intensity is inversely correlated with slurry accumulation, such that surfaces with lower fluorescence intensity or brightness correspond to higher levels of slurry accumulation.

[0046] One or more regions of interest on each surface may be coated with a fluorescent material. Alternatively, the entire surface may be coated with a fluorescent material. In some embodiments, the fluorescent material includes fluorescent paint or fluorescent tape. In some embodiments, the fluorescent material may fluoresce upon exposure to ultraviolet radiation. A region of interest may correspond to a specific problem area. Alternatively, a region of interest may generally represent an area of ​​slurry buildup on the surface. In some embodiments, the fluorescent material is applied to regions of interest on multiple different surfaces.

[0047] In some other embodiments, instead of using a fluorescent material coating, the slurry 135 itself may contain fluorescent additives to facilitate the monitoring of slurry buildup. In such embodiments, fluorescence intensity is positively correlated with slurry buildup, such that a surface with higher fluorescence intensity or brightness corresponds to a higher level of slurry buildup.

[0048] To monitor the accumulation of slurry 135 on a surface, the polishing apparatus 100 includes at least one light source for illuminating the surface, at least one sensor for measuring the fluorescence intensity of a region of interest on the surface, and a processor for monitoring the accumulation of slurry on the surface. In the illustrated embodiment, the polishing apparatus includes multiple cameras for illuminating and detecting the fluorescence intensity of specific regions of interest within the polishing apparatus 100. Figures 1B to 1C The diagram schematically illustrates cameras. Each camera can be mounted on a support (not shown) and / or directly or indirectly coupled to a corresponding component of the polishing apparatus 100. In some embodiments, each camera is fixed relative to the polishing apparatus 100. In some other embodiments, one or more cameras are movable relative to the polishing apparatus 100 for repositioning and / or reorienting the cameras to change their field of view. Furthermore, each camera is coupled to a controller 190. Figure 1A And controlled by controller 190.

[0049] In some implementations, the buildup of slurry 135 may occur primarily on the upward-facing surface immediately adjacent to the worktable 120. Therefore, it may be desirable to position one or more of a plurality of cameras for top-down viewing of surfaces adjacent to the worktable 120, such as surfaces vertically above, vertically below, or radially surrounding the worktable 120.

[0050] In some embodiments, each camera includes a light source and an image sensor. Alternatively, the light source may be separate from the camera. For example, the light source may be a separate component of the polishing apparatus 100. In one example, the light source may include one or more light strips within the housing 101 of the polishing apparatus 100 for illuminating the processing area 105. In some embodiments, the light source is any ultraviolet light source. For example, the ultraviolet light source may be a source that emits ultraviolet radiation in the range of about 315 nm to about 400 nm, which is commonly referred to as ultraviolet A radiation or black light. In some embodiments, the light source includes an array of light-emitting diodes. In some embodiments, each camera uses a lens capable of imaging an expanded field of view, such as a wide-angle or fisheye lens. In some embodiments, each camera has a filter that matches the fluorescence wavelength range of the fluorescent material. In some embodiments, a single camera is configured to simultaneously image regions of interest on multiple different surfaces.

[0051] The polishing apparatus 100 includes a camera 151 disposed above a support head 126. The camera 151 may be coupled to an overhead track 128 or a bracket 108 (e.g.,...). Figure 1A At least one of (shown). The position and orientation of camera 151 enable imaging of the surface of the carrier head 126 (such as the surface of housing 129).

[0052] The polishing apparatus 100 includes a camera 152 disposed above a polishing station 124. The camera 152 may be coupled to at least one of an upper wall 103 or a side wall 104. The position and orientation of the camera 152 enable it to perform polishing on the surface of a bearing head 126 or on one or more structures above the bearing head 126, such as an overhead track 128, a drive system 106, a drive shaft 107, or a bracket 108 (e.g., ...). Figure 1A The surface shown is imaged.

[0053] The polishing apparatus 100 includes a camera 153 positioned above the spray bar 134. The camera 153 can be coupled to the upper wall 103, side wall 104, overhead track 128, drive system 106, or bracket 108 (e.g., Figure 1A At least one of (shown). The position and orientation of camera 153 enable imaging of the surface of spray bar 134, such as the surface of arm 136.

[0054] The polishing apparatus 100 includes a camera 154 disposed in the processing area 105 (e.g., adjacent to camera 152). Camera 154 may be coupled to an upper wall 103, a side wall 104, an overhead track 128, a drive system 106, or a bracket 108 (e.g., Figure 1A At least one of (shown). The position and orientation of camera 154 enable imaging of the surface of sidewall 104.

[0055] The polishing apparatus 100 includes a camera 155 positioned above the polishing cup 146. The camera 155 can be coupled to an overhead track 128, a drive system 106, or a bracket 108 (e.g.,...). Figure 1A At least one of (shown). The position and orientation of camera 155 enable imaging of the surface of cup 146, such as the inner wall surface 147.

[0056] The polishing apparatus 100 includes a camera 156 disposed above the pad adjustment device 112. The camera 156 may be coupled to the upper wall 103, side wall 104, overhead track 128, drive system 106, or bracket 108 (e.g., Figure 1A At least one of (shown). The position and orientation of the camera 156 enable imaging of the surface of the pad adjustment device 112 (such as the surface of the arm 113, the adjuster head 115, or the motor 117).

[0057] Figure 2 This is a diagram illustrating a method 200 for monitoring slurry buildup. Method 200 can be executed by a controller 190. In one example, the controller 190 includes a non-transitory computer-readable medium thereon storing instructions for executing method 200. At activity 202, substrate 114 is polished in polishing apparatus 100 using slurry 135. Specifically, as... Figure 1B As shown, slurry 135 is dispensed from the spray bar 134 onto the polishing surface 131 of the polishing pad 130. As described above, some slurry buildup may occur on the inner surface of the housing 101 due to accidental splashing, spraying, and / or atomization. Normally, slurry buildup is undetectable. However, as disclosed herein, one or more regions of interest on the inner surface of the polishing apparatus 100 are coated with a fluorescent material. Therefore, slurry buildup on the regions of interest covers the fluorescent coating, which reduces the measurable fluorescence intensity or brightness of the fluorescent material in the regions of interest. Figure 3 This is a schematic diagram of an exemplary setup 300 for monitoring slurry buildup 301 on surface 302. (Reference) Figure 3 The region of interest 304 is coated with fluorescent material 306. As portions of the fluorescent material 306 are covered by the slurry buildup 301, the measurable fluorescence intensity of the region of interest 304 decreases.

[0058] At activity 204, light source 308 is turned on to illuminate surface 302 including region of interest 304. In some embodiments, the light source is turned on for a period of about 1 second or less, such as from about 1 millisecond to about 1 second, from about 1 millisecond to about 100 milliseconds, or from about 1 millisecond to about 10 milliseconds. It may be desirable to limit the exposure time in order to reduce the possibility of photocorrosion of substrate 114 or other sensitive materials within the housing 101 of polishing apparatus 100. In some embodiments, when light source 308 is turned on, auxiliary lighting (such as normal indoor lighting in a manufacturing plant) may be optionally turned off to prevent interference with fluorescence measurements, as described in more detail below.

[0059] At activity 206, when the region of interest 304 is illuminated, the fluorescence intensity of the region of interest is measured using a sensor, such as an image sensor 310. The fluorescence intensity may correspond to the amount of slurry deposit 301 on the region of interest 304. In some embodiments, the sensor may be calibrated to work optimally with a specific type of fluorescent material and the illumination being implemented. In some embodiments, the sensor measures the fluorescence intensity, which may be normalized to that of fluorescent material in a clean state. In the illustrated embodiment with an image sensor 310, the measurement of fluorescence intensity includes capturing an image of the surface using the image sensor 310. In one example, a light source 308 and an image sensor 310 are included in a camera, such as... Figure 1B and Figure 1C In one of the cameras 151 to 156 shown. Although an image sensor is depicted in the illustrated embodiment, any suitable fluorescence measurement sensor can be used.

[0060] In some embodiments, sensor measurements include data representing fluorescence outside region 304 of interest. For example, image sensor 310 may capture an image of region 312, which includes region 304 of interest and the area surrounding region 314 of interest. In such embodiments, data processing is performed to select region 304 of interest before determining fluorescence intensity. For example, when the captured image includes the area surrounding region 314 of interest, region 304 of interest may be selected by applying a computer algorithm to the image. To provide an executable indication of slurry buildup, it may be desirable to convert the fluorescence intensity of region 304 of interest into a number representing the amount of slurry buildup 301.

[0061] At activity 208, the fluorescence intensity is compared to a first range. The first range may include a lower limit of fluorescence intensity in the region of interest; below this lower limit, the region of interest is considered to require cleaning. In other words, fluorescence intensity measured within the first range can be considered "clean," while fluorescence intensity measured outside the first range can be considered "dirty." For example, the lower limit of the first range may correspond to a threshold level for residue thickness, residue coverage percentage, and / or residue non-uniformity in the region of interest.

[0062] In some examples, residue inhomogeneity in the region of interest can be monitored, either in addition to or as an adjunct to the total fluorescence intensity as described above. Residue inhomogeneity can be a particularly useful tracking parameter after the polishing apparatus is returned to online following cleaning. This is because changes in slurry buildup can be detected before they become apparent in terms of total fluorescence intensity, via measurements of fluorescence intensity inhomogeneity. In other words, as slurry buildup occurs, fluorescence intensity inhomogeneity in the region of interest may decrease to a detectable level even before changes in total fluorescence intensity become detectable. In one example, fluorescence intensity measurements can be combined with edge detection of discrete points where slurry buildup occurs to aid in monitoring changes in inhomogeneity.

[0063] At activity 210, an alarm is created if the fluorescence intensity is outside the first range or meets a threshold condition associated with the first range. The alarm may include a user message indicating that cleaning is required. The alarm may specify a particular surface that needs cleaning, such as a surface corresponding to an area of ​​interest identified as outside the first range. The alarm may include a summary screen to display to the user one or more ratings representing slurry buildup on different surfaces of the polishing apparatus 100.

[0064] At activity 212, cleaning of the surface, including the area of ​​interest, is scheduled and / or initiated based on an alarm. In some embodiments, cleaning is performed while the polishing apparatus 100 remains online. For example, between polishing sessions, components of the polishing apparatus 100, such as the bracket head 126 or the spray bar 134, may be intermittently rinsed or cleaned with deionized water or another suitable rinsing fluid. Using the apparatus and / or methods disclosed herein, rinsing can be scheduled and / or initiated based on an alarm. Furthermore, using the apparatus and / or methods disclosed herein, rinsing can be modified, such as by providing a longer rinsing time or a specific spray formulation, for targeted cleaning of surfaces including the area of ​​interest corresponding to the alarm at activity 210.

[0065] In some other embodiments, the polishing apparatus 100 is taken offline to perform preventative maintenance cleaning. For example, when the polishing apparatus 100 is offline, components of the polishing apparatus 100 can be manually wiped. Using the apparatus and / or methods disclosed herein, preventative maintenance cleaning can be scheduled based on alarms. For example, cleaning can be automatically scheduled for at least surfaces including the area of ​​interest corresponding to the alarm at activity 210. Scheduling tool cleaning only when needed provides more efficient cleaning scheduling and reduced tool downtime. Furthermore, cleaning only specific areas of the polishing apparatus 100 provides more efficient cleaning of selected surfaces and reduced tool downtime. Additionally, the cleaning process can be optimized by prioritizing the surfaces that require cleaning most.

[0066] Although the foregoing describes embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, the scope of which is defined by the appended claims.

Claims

1. A substrate polishing apparatus, comprising: The surface is at least partially coated with a fluorescent material; A light source configured to illuminate the surface; An image sensor configured to image the surface; as well as A processor coupled to the image sensor and configured to use data supplied from the image sensor to monitor the accumulation of slurry on the fluorescent material on the surface.

2. The substrate polishing apparatus of claim 1, wherein the surface includes a portion of at least one of a support head, an overhead track, a spray bar, a sidewall, a stand cup, or a pad adjustment device.

3. The substrate polishing apparatus of claim 1, wherein the fluorescent material comprises at least one of fluorescent coating or fluorescent strip.

4. The substrate polishing apparatus of claim 1, wherein the light source includes ultraviolet light.

5. The substrate polishing apparatus of claim 1, wherein the light source and the image sensor are included in a camera, the camera using at least one of a wide-angle or fisheye lens, the wide-angle or fisheye lens being configured to image an expanded field of view.

6. The substrate polishing apparatus of claim 1, wherein the image sensor includes a filter that is matched to the fluorescence wavelength range of the fluorescent material.

7. The substrate polishing apparatus of claim 1, wherein the fluorescent material is applied to regions of interest on a plurality of different surfaces, and wherein the image sensor comprises one or more image sensors configured to simultaneously image each region of interest within the regions of interest, and wherein the processor is configured to monitor the amount of slurry buildup on the regions of interest using data supplied by the one or more image sensors.

8. The substrate polishing apparatus of claim 1, wherein the processor includes a non-transitory computer-readable medium storing instructions thereon for a monitoring method, the monitoring method comprising the following steps: Capture an image of the surface containing the fluorescent material; Select the region of interest in the image; as well as Determine the fluorescence intensity of the region of interest, wherein the fluorescence intensity corresponds to the amount of slurry deposited on the region of interest.

9. A method for monitoring slurry accumulation, comprising the following steps: Capture images of the surface of the polishing apparatus, wherein the surface is at least partially coated with a fluorescent material; Select the region of interest in the image; as well as Determine the fluorescence parameters of the region of interest, wherein the values ​​of the fluorescence parameters correspond to the amount of slurry deposited on the fluorescent material in the region of interest.

10. The method of claim 9, wherein the fluorescence parameter includes at least one of fluorescence intensity or fluorescence intensity non-uniformity.

11. The method of claim 9, further comprising the following steps: The surface is illuminated with a light source during the step of capturing the image.

12. The method of claim 9, wherein the step of selecting the region of interest comprises the following steps: Computer algorithms are applied to the image.

13. The method of claim 9, wherein the region of interest corresponds to a portion of the surface coated with the fluorescent material.

14. The method of claim 9, further comprising the following steps: The value of the fluorescence parameter is compared with a first range; and An alarm is created if the value of the fluorescence parameter satisfies a threshold condition associated with the first range.

15. The method of claim 14, further comprising at least one of the following steps: scheduling or initiating cleaning of the surface including the region of interest based on the alarm.

16. A substrate polishing apparatus, comprising: The surface is at least partially coated with a fluorescent material; A light source configured to illuminate the surface; A sensor configured to measure the fluorescence intensity of a region of interest on the surface; as well as A non-transitory computer-readable medium having instructions stored thereon for a monitoring method, the monitoring method comprising the following steps: The substrate is polished with a paste in the substrate polishing apparatus, wherein the accumulation of paste on the fluorescent material on the surface reduces the measurable fluorescence intensity of the region of interest; Turn on the light source; When the light source is turned on, the fluorescence intensity of the region of interest is measured using the sensor; The measured fluorescence intensity was compared with a first range; and An alarm is created if the measured fluorescence intensity is outside the first range.

17. The substrate polishing apparatus of claim 16, wherein the fluorescent material comprises at least one of a fluorescent coating or a fluorescent strip, and wherein the light source comprises ultraviolet light.

18. The substrate polishing apparatus of claim 16, wherein the sensor includes an image sensor, and wherein the monitoring method further includes the following steps: The image sensor is used to capture an image of the surface.

19. The substrate polishing apparatus of claim 18, wherein the monitoring method further comprises the following steps: Select the region of interest in the image that corresponds to a portion of the surface coated with the fluorescent material.

20. The substrate polishing apparatus of claim 16, wherein the monitoring method further comprises at least one of the following steps: scheduling or initiating cleaning of the surface including the region of interest based on the alarm.

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