Polishing Pad Conditioning Apparatus

This application is a continuation of U.S. Non-Provisional patent application Ser. No. 18/130,267, titled “POLISHING PAD CONDITIONING APPARATUS” and filed on Apr. 3, 2023, which is a continuation of U.S. Non-Provisional patent application Ser. No. 16/921,092, titled “POLISHING PAD CONDITIONING APPARATUS” and filed on Jul. 6, 2020, which claims priority to U.S. Provisional Patent Application 62/894,656, titled “SEMICONDUCTOR CHEMICAL MECHANICAL POLISHING (CMP) WITH COMPOSITE MATERIAL” and filed on Aug. 30, 2019. U.S. Non-Provisional patent application Ser. No. 18/130,267, U.S. Non-Provisional patent application Ser. No. 16/921,092, and U.S. Provisional Patent Application 62/894,656 are incorporated herein by reference.

Chemical mechanical polishing (CMP) is a widely used process by which both chemical and physical forces are used to globally planarize a semiconductor workpiece, such as a wafer. Generally, the planarization prepares the workpiece for the formation of a subsequent layer. A typical CMP tool comprises a rotating platen covered by a polishing pad. A slurry distribution system is configured to provide a polishing mixture, having chemical and abrasive components, to the polishing pad. A workpiece is then brought into contact with the rotating polishing pad to planarize the workpiece.

The following disclosure provides several different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation illustrated in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

One or more polishing pad conditioning apparatuses for conditioning a semiconductor wafer polishing pad are provided herein. According to some embodiments, a polishing pad conditioning apparatus comprises a base structure having protrusions protruding from a surface of the base structure. According to some embodiments, the base structure is an elliptical disk and at least some of the protrusions are composites. According to some embodiments, at least some of the composite protrusions comprise a polymer circumscribing a fiber. According to some embodiments, the fiber protrudes beyond a tip portion of the polymer. According to some embodiments, the protrusions are arranged in clusters of protrusions on the base structure. According to some embodiments, a plurality of clusters of protrusions are arranged in the form of an ellipse on the base structure. According to some embodiments, several pluralities of clusters are arranged in the form of several ellipses on the base structure. According to some embodiments, the several ellipses are concentric circles. According to some embodiments, some protrusions within a cluster of protrusions are a first height, while other protrusions within the cluster of protrusions are a second height. According to some embodiments, the second height is different than the first height.

is a top view of a polishing pad conditioning apparatus, according to some embodiments. According to some embodiments, the polishing pad conditioning apparatusincludes protrusionsattached to a base. According to some embodiments, the basecomprises a substrate, disk, platform, support structure, or other suitable device or foundation. According to some embodiments, the basecomprises at least one of metal, polymer, crystalline material, non-crystalline material, substance, mixture of substances, or other suitable materials. According to some embodiments, the baseis a substrate comprising a semiconductor material. In some embodiments, the basecomprises at least one of silicon, germanium, carbide, gallium, arsenide, germanium, arsenic, indium, oxide, sapphire, or other suitable materials.

According to some embodiments, the shape of the baseis at least one of conical, disk-like, geometric, elliptical, polygonal, symmetrical, asymmetrical, irregular, or other suitable shape. According to some embodiments, the baseis at least one of circular, oval, rounded, or other shape having one or more foci. According to some embodiments, the baseincludes a peripheral portion, such as at or near a perimeter of the base, and a center portion. According to some embodiments, the protrusionsare located between the peripheral portionand the center portion. According to some embodiments, the protrusionsare located at least one of at the peripheral portion, at the center portion, or between the peripheral portionand the center portion.

According to some embodiments, the protrusionsprotrude away from the surfaceof the base. According to some embodiments, some protrusionsprotrude away from and perpendicular to the surfaceof the base. According to some embodiments, some protrusionsprotrude away from the baseat an angle that is not perpendicular to the surfaceof the base. According to some embodiments, some protrusionsprotrude away from and perpendicular to the surfaceof the base, and some other protrusionsprotrude away from the baseat an angle that is not perpendicular to the surfaceof the base.

According to some embodiments, two or more protrusions are arranged as a cluster of protrusionson the base. According to some embodiments, a cluster of protrusionsrefers to multiple protrusions positioned closely together.

According to some embodiments, the polishing pad conditioning apparatusincludes one or more clusters of protrusions. According to some embodiments, a plurality of clusters of protrusionsare arranged on the basein the form of an ellipse. According to some embodiments, an ellipse is at least one of circular, oval, rounded, or other shape having one or more foci. According to some embodiments, the ellipsedefines a zone of the base. According to some embodiments, multiple pluralities of clusters of protrusions are arranged as multiple concentric ellipses on the base. According to some embodiments, multiple pluralities of clusters of protrusions are arranged as multiple concentric circles on the base. According to some embodiments, a first plurality of clusters of protrusionsis a first distance from the perimeter of the base, and a second a plurality of clusters of protrusionsis a second distance from the perimeter of the base. According to some embodiments, the first distance is greater than the second distance.

According to some embodiments, a plurality of clusters of protrusionsare arranged as one or more geometric shapes on the base. According to some embodiments, a geometric shape comprising a plurality of clusters of protrusionsdefines a zone of the polishing pad conditioning apparatus. According to some embodiments, the polishing pad conditioning apparatuscomprises one or more zones. According to some embodiments, one or more clusters of protrusions, such as-, are arranged between the center portionand the peripheral portionof the base. According to some embodiments, the polishing pad conditioning apparatushas a first zone that is a first shape and a second zone that is a second shape different than the first shape. According to some embodiments, the polishing pad conditioning apparatushas a first zone that is elliptical and a second zone that is between the center portionof the baseand the peripheral portionof the base. According to some embodiments, the polishing pad conditioning apparatushas any number of zones. According to some embodiments, the polishing pad conditioning apparatushas any number of protrusions. According to some embodiments, the protrusionsare arranged relative to one another in any manner, configuration, etc. According to some embodiments, the polishing pad conditioning apparatushas any number of clusters of protrusions. According to some embodiments, the clusters of protrusionsare arranged relative to one another in any manner, configuration, etc.

According to some embodiments, the baseincludes one or more mounting mechanismsfor attaching the polishing pad conditioning apparatusto a wafer polishing apparatus. According to some embodiments, the one or more mounting mechanismsare at least one of a female fitting, a male fitting, a connector, a clasp, an aperture, a recess, or other suitable item. According to some embodiments, at least some of the one or more mounting mechanismsare an aperture or recess fashioned into or through the base. According to some embodiments, at least some of the one or more mounting mechanismsare attached to the base, such as a connector, clasp, etc. joined to the baseby soldering, fusing, chemical bonding, etc.

is a top view of a cluster of protrusions, according to some embodiments. According to some embodiments, the cluster of protrusionscomprises a plurality of protrusionsarranged as at least one of elliptical, polygonal, geometric, concentric, linear, symmetrical, asymmetrical, or other suitable arrangements. According to some embodiments, the protrusionsare positioned on the base in an unarranged configuration.

is an illustration of a plurality of clusters of protrusions, namely a first cluster of protrusions, a second cluster of protrusions, a third cluster of protrusions, and a fourth cluster of protrusionsof a polishing pad conditioning apparatus, according to some embodiments. According to some embodiments, the first cluster of protrusionsincludes a first number of protrusions, the second cluster of protrusionsincludes a second number of protrusions, the third cluster of protrusionsincludes a third number of protrusions, and the fourth cluster of protrusionsincludes a fourth number of protrusions. According to some embodiments, at least one of the first number of protrusions, the second number of protrusions, the third number of protrusions, or the fourth number of protrusions is different than the number of protrusions of another cluster of protrusions. According to some embodiments, the protrusionsof the first cluster of protrusionsare arranged in a first arrangement, the protrusionsof the second cluster of protrusionsare arranged in a second arrangement, the protrusionsof the third cluster of protrusionsare arranged in a third arrangement, and the protrusionsof the fourth cluster of protrusionsare arranged in a fourth arrangement. According to some embodiments, at least one of the first arrangement, the second arrangement, the third arrangement, or the fourth arrangement is different than the arrangement of protrusions of another cluster of protrusions. According to some embodiments, the first cluster of protrusions, the second cluster of protrusions, the third cluster of protrusions, and the fourth cluster of protrusionsare separated from one another by any distance, dimension, etc. According to some embodiments, distances, dimensions, etc. between different clusters of protrusions vary.

illustrates a cluster of protrusions, according to some embodiments. According to some embodiments, proximate endsto the surfaceof the baseof some protrusionsare directly attached to the base. According to some embodiments, proximate endsto the surfaceof the baseof some protrusionsare indirectly attached to the base, such as by an intermediary, a mount, a connector, a support, or other suitable structures (not shown).

According to some embodiments, the proximate endsto the surfaceof the baseof some protrusionsare embedded in the base. According to some embodiments, the proximate endsto the surfaceof the baseof some protrusionsare friction fit into the base. According to some embodiments, the proximate endsto the surfaceof the baseof some protrusionsare heat bonded to or into the base. According to some embodiments, the proximate endsto the surfaceof the baseof some protrusionsare chemically bonded to or into the base. According to some embodiments, the proximate endsto the surfaceof the baseof some protrusionsare mechanically bonded to or into the base. According to some embodiments, at least some protrusionsinclude at least one wafer conditioning material.

According to some embodiments, at least some protrusionsof the cluster of protrusionsare bound together and attached to the baseas a group. According to some embodiments, at least some protrusionsof the cluster of protrusionsare individually attached to the base.

According to some embodiments, some protrusionsare of uniform length. According to some embodiments, some protrusionsare of non-uniform length, such that the length of some protrusionsof the cluster of protrusionsis different than the length of some other protrusionsof the cluster of protrusions. According to some embodiments, some protrusionsof the cluster of protrusionshave a first length, some other protrusionsof the cluster of protrusionshave a second length, and yet other protrusionsof the cluster of protrusionshave a third length. According to some embodiments, the first length is different than the second length and the third length, and the second length is different than the third length. According to some embodiments, the cluster of protrusionscomprises protrusionsof more than three different lengths.

According to some embodiments, in use some protrusionsof the cluster of protrusionshave a first polishing performance, some other protrusionsof the cluster of protrusionshave a second polishing performance, and yet other protrusionsof the cluster of protrusionshave a third polishing performance. According to some embodiments, the first polishing performance is greater than the second polishing performance, and the second polishing performance is greater than the third polishing performance. According to some embodiments, initially the first polishing performance is greater than the second and third polishing performances, and subsequently the second polishing performance is greater than the first and third polishing performances. According to some embodiments, the third polishing performance is greater than the first and second polishing performances.

According to some embodiments, some protrusionsof the cluster of protrusionswear down over time due to frictional contact with one or more polishing pads during conditioning. According to some embodiments, when the cluster of protrusionsis initially put to use for conditioning polishing pads, the longer protrusions, such as at least one protrusion, contact the surfaces of the polishing pads to a greater extent than the shorter protrusions, such as at least one other protrusion. According to some embodiments, the protrusions that contact the surface of the polishing pads to a greater extent have a greater polishing effect or performance. As the cluster of protrusionspolishes pads over time, the longer protrusions will, on average, wear down sooner than the shorter protrusions. According to some embodiments, when the wafer conditioning materialof a longer protrusion wears down to at or below a tip portion, the protrusion becomes less effective at polishing. However, according to some embodiments, the full or partial length of the conditioning material of shorter protrusions sustains an effective polishing performance of the cluster of protrusions. Thus, according to some embodiments, initially the longer protrusions contact the polishing pads more so than the shorter protrusions, and the longer protrusions have a more effective polishing performance than do the shorter protrusions. Over time of use, the longer protrusions wear down and the relatively shorter protrusions have a greater polishing effect than do the worn down longer protrusions. According to some embodiments, the level of the polishing effect or performance of a cluster of protrusions having protrusions of different lengths is maintained to a higher degree as compared to a cluster of protrusions having all protrusions of the same length.

Referring to, according to some embodiments a protrusioncomprises more than one material and is, at times, referred to as a composite protrusion. According to some embodiments, the composite protrusion comprises a polishing componentand a reinforcement component. According to some embodiments, the polishing componentprotrudes beyond a tip portionof the reinforcement component. According to some embodiments, below the tip portionthe reinforcement componentcompletely encompasses or surrounds the polishing component. According to some embodiments, below the tip portionthe reinforcement componentpartially encompasses or surrounds the polishing component. According to some embodiments, the reinforcement componentencircles the polishing component. According to some embodiments, the reinforcement componentpartially encircles the polishing component. According to some embodiments, the reinforcement componentbuttresses the entire periphery of the polishing component. According to some embodiments, the reinforcement componentbuttresses a portion of the periphery of the polishing component. According to some embodiments, the reinforcement componentbuttresses one side of the polishing component. According to some embodiments, the reinforcement componentbuttresses more than one side of the polishing component. According to some embodiments, the reinforcement componentis a sheath. According to some embodiments, the reinforcement componenthas apertures, gaps, or slits. According to some embodiments, the reinforcement componenthas a closed body. According to some embodiments, the reinforcement componentcomprises segments. According to some embodiments, the reinforcement componentcomprises a plurality of threads.

is a cross-sectional view of a protrusioncomprising more than one material, according to some embodiments. According to some embodiments, the polishing componentextends lengthwise along an interior portion of the reinforcement component. According to some embodiments, the polishing componentextends lengthwise along a center portion of the reinforcement component. According to some embodiments, the polishing componentextends partially along a center portion of the reinforcement component. According to some embodiments, the polishing componentextends along a peripheral portion of the reinforcement component. According to some embodiments, the polishing componenthas a length that is greater than the length of the reinforcement component. According to some embodiments, the polishing componenthas a length that is less than the length of the reinforcement componentand protrudes beyond the tip portion.

According to some embodiments, the polishing componentis a single component. According to some embodiments, the polishing componentcomprises more than one component. According to some embodiments, the polishing componentcomprises two or more coupled components. According to some embodiments, the polishing componentcomprises two or more distinct components. According to some embodiments, the polishing componentcomprises a composite of materials. According to some embodiments, the polishing componentcomprises one or more conditioning fibers. According to some embodiments, the polishing componentcomprises at least one carbon fiber.

According to some embodiments, the polishing componentis inflexible. According to some embodiments, the polishing componentis predominantly inflexible. According to some embodiments, the polishing componentis rigid. According to some embodiments, the polishing componentis predominantly rigid. According to some embodiments, the polishing componentis brittle.

According to some embodiments, the tensile strength of the polishing componentis greater than 300 kilopounds per square inch (ksi) and less than 700 ksi. According to some embodiments, the tensile strength of the polishing componentis greater than 450 ksi and less than 550 ksi.

According to some embodiments, the density of the polishing componentis greater than 1.0 g/cmand less than 3.0 g/cm. According to some embodiments, the density of the polishing componentis greater than 1.5 g/cmand less than 1.7 g/cm.

According to some embodiments, the modulus of elasticity of the polishing componentis greater than 15 mega-pounds per square inch (Msi) and less than 30 Msi. According to some embodiments, the modulus of elasticity of the polishing componentis greater than 18 Msi and less than 22 Msi.

According to some embodiments, the polishing componentis chemical resistant. According to some embodiments, the polishing componentremains stable at temperatures above 300° Fahrenheit. According to some embodiments, the coefficient of thermal expansion of the polishing componentis negative.

According to some embodiments, the polishing componentcomprises carbon. According to some embodiments, the polishing componentcomprises carbon crystals. According to some embodiments, the polishing componentcomprises carbon fiber. According to some embodiments, the carbon content of the polishing componentis greater than 90% by weight.

According to some embodiments, the polishing componentcomprises glass. According to some embodiments, the polishing componentcomprises glass fiber. According to some embodiments, the polishing componentcomprises plastic. According to some embodiments, the polishing componentcomprises plastic fiber. According to some embodiments, the polishing componentcomprises a composite of at least one of carbon, glass, or plastic. According to some embodiments, the polishing componentcomprises a plurality of at least one of carbon fibers, glass fibers, or plastic fibers.

According to some embodiments, the polishing componentis turbostratic. According to some embodiments, the polishing componentis graphitic. According to some embodiments, the polishing componentis a hybrid structure with both graphitic and turbostratic components.

According to some embodiments, the diameter of the polishing componentis less than 1 micrometer (mm). According to some embodiments, the diameter of the polishing componentis greater than 1 mm and less than 120 mm. According to some embodiments, the diameter of the polishing componentis less than the diameter of the reinforcement component. According to some embodiments, the polishing component comprises multiple components having a diameter that is less than the diameter of the reinforcement component.

According to some embodiments, the reinforcement componentis a single component. According to some embodiments, the reinforcement componentis comprised of more than one component. According to some embodiments, the reinforcement componentis comprised of two or more intertwined components. According to some embodiments, the reinforcement componentis comprised of two or more distinct components. According to some embodiments, the reinforcement componentis composite matter.

According to some embodiments, the reinforcement componenthas properties that are similar to the properties of the polishing component. According to some embodiments, the reinforcement componenthas properties that are different from the properties of the polishing component. According to some embodiments, the reinforcement componentis inflexible. According to some embodiments, the reinforcement componentis marginally flexible. According to some embodiments, the reinforcement componentis rigid. According to some embodiments, the reinforcement componentis predominantly rigid. According to some embodiments, the reinforcement componentis more rigid than the polishing component. According to some embodiments, the reinforcement componentis less brittle than the polishing component. According to some embodiments, the reinforcement componentis more resistant to fracturing than the polishing component.

According to some embodiments, the reinforcement componentis resistant to chemicals. According to some embodiments, the reinforcement componentuptakes and absorbs little to no moisture. According to some embodiments, the reinforcement componentis resistant to heat and maintains mechanical strength and dimension across a broad temperature range. According to some embodiments, the reinforcement componentis rigid and resistant to creep, and retains stiffness and strength in a broad range of environmental conditions.

According to some embodiments, the tensile strength of the reinforcement componentis greater than 10 ksi and less than 20 ksi. According to some embodiments, the tensile strength of the reinforcement componentis greater than 12 ksi and less than 16 ksi.

According to some embodiments, the density of the reinforcement componentis greater than 0.5 g/cm, and less than 3.0 g/cm. According to some embodiments, the density of the reinforcement componentis greater than 1.2 g/cmand less than 1.4 g/cm.

According to some embodiments, the modulus of elasticity of the reinforcement componentis greater than .25 Msi and less than 1 Msi. According to some embodiments, the modulus of elasticity of the reinforcement componentis greater than .5 Msi and less than .6 Msi.

According to some embodiments, the reinforcement componentis chemical resistant. According to some embodiments, the reinforcement componentremains stable at temperatures above 300° Fahrenheit. According to some embodiments, the coefficient of thermal expansion of the reinforcement componentis positive.

According to some embodiments, the reinforcement componentcomprises a polymer. According to some embodiments, the reinforcement componentcomprises a semi-crystalline thermoplastic. According to some embodiments, the reinforcement componentcomprises polyetheretherketone (PEEK).

According to some embodiments, the protrusioncomprises a polishing componentcomprising carbon, carbon crystals, or carbon fibers, and a reinforcement componentcomprising a polymer, semi-crystalline thermoplastic, or PEEK.

illustrates several protrusionsof different lengths, namely a first protrusion, a second protrusion, and a third protrusion, according to some embodiments. According to some embodiments, reinforcement componentof the first protrusionhas a length L, reinforcement componentof the second protrusionhas a length L, and reinforcement componentof the third protrusionhas a length L. According to some embodiments, the length Lof reinforcement componentis the distance from the reinforcement tipto the reinforcement end, the length Lof reinforcement componentis the distance from the reinforcement tipto the reinforcement end, and the length Lof reinforcement componentis the distance from the reinforcement tipto the reinforcement end. According to some embodiments, the initial length of a reinforcement componentis the length of the reinforcement prior to first use of the reinforcement component for conditioning a polishing pad. According to some embodiments, the initial lengths L, L, and Ls of the reinforcement components,, andare greater than 1 millimeter (mm) and less than 20 mm. According to some embodiments, a removal rate of debris, contaminants, non-uniformities, etc. from a polishing pad is maintained substantially constant throughout the process lifetime of the reinforcement components,, andif the initial lengths L, L, and Lof the reinforcement components,, andare within a range of 1 mm to 20 mm. According to some embodiments, the first length Lis different than the second length L, and the third length Ls is different than the first length Land the second length L. According to some embodiments, if the initial lengths of the reinforcement components,, andare greater than 20 mm, then at least some of the reinforcement components,, andbend, buckle, etc. which inhibits removal of debris, contaminants, non-uniformities, etc. According to some embodiments, if the initial lengths of the reinforcement components,, andare less than 1 mm, then a service life of the polishing pad conditioning apparatusis reduced below a desired threshold.

According to some embodiments, the diameters D, D, and Dof the reinforcement components,, andare greater than 1 mm and less than 120 mm. According to some embodiments, the diameters D, D, and Dof the reinforcement components,, andare inversely proportional to the number of protrusionsthat together are attached to the base. According to some embodiments, the greater the diameters D, D, and D, the fewer the number of protrusionsthat are together attached to the base. According to some embodiments, the lesser the diameters D, D, and D, the greater the number of protrusionsthat are together attached to the base. According to some embodiments, reinforcement components,, andhaving diameters D, D, and Ds within a range of 1 mm to 120 mm provides for a quantity of protrusionsattached to the baseto amply conditioning of a polishing pad by the polishing pad conditioning apparatus.

According to some embodiments, the diameters D, D, and Ds of the reinforcement components,, andare the same. According to some embodiments, the diameters D, D, and Dof the reinforcement components,, andare different. According to some embodiments, some reinforcement components have a first diameter, and some other reinforcement components have a second diameter. According to some embodiments, the first diameter is different than the second diameter. According to some embodiments, some reinforcement components have a first diameter, some other reinforcement components have a second diameter, and yet some other reinforcement components have a third diameter. According to some embodiments, the first diameter is different than the second diameter, and the third diameter is different than the first and second diameters.

According to some embodiments, the differences (d, d, and d+d) in the initial lengths among protrusions,, andare greater than .1 mm and less than 20 mm. According to some embodiments, differences in initial lengths that are greater than .1 mm and less than 20 mm provide that a next-lower length protrusionwill contact a polishing pad prior to a longer protrusionwearing down and becoming ineffective at conditioning a polishing pad, so that at least some protrusions remain in contact with polishing pad. According to some embodiments, some protrusions among several protrusions are of a first length and some other protrusions among the several protrusions are of a second length. According to some embodiments the first length is different than the second length. According to some embodiments, some protrusions among several protrusions are of a first length, some other protrusions among the several protrusions are of a second length, and yet some other protrusions among the several protrusions are of a third length. According to some embodiments, the first length is different than the second length, and the third length is different than the first length and the second length.

According to some embodiments the difference in length damong some protrusions of several protrusions is different than the difference in length damong some other protrusions of the several protrusions. According to some embodiments, d≠d.

illustrates a wafer polishing apparatus, according to some embodiments. According to some embodiments, the wafer polishing apparatusincludes three plates, three wafer polishing pads, three slurry injection units, four polishing head units, and three polishing pad conditioning apparatusescoupled to three support arms. According to some embodiments, the three platesare configured to receive the three wafer polishing pads. According to some embodiments, the three wafer polishing padsare configured to be secured over the top surface of the three plates. According to some embodiments, the wafer polishing apparatusincludes four support structurescoupled to the four polishing head units. According to some embodiments, the four support structuresare at least one of rods, beams, bars, or other suitable structures and intersect a point of rotation. According to some embodiments, the three polishing pad conditioning apparatusesare coupled to the three support armsby the one or more mounting mechanisms().

According to some embodiments, the wafer polishing apparatusincludes a loading plate unitconfigured to secure wafers for polishing. According to some embodiments, the loading plate unitincludes a holding unitconfigured to hold a stack of wafers. According to some embodiments, the undersides of the four polishing head unitsare configured to secure thereto wafers from the holding unit. According to some embodiments, the undersides of the four polishing head unitsinclude chucks (not shown) configured to secure a top wafer from the holding unit. According to some embodiments, the wafer polishing apparatusis configured to rotate the four support structuresby 90-degree increments about the point of rotationin a clockwise or counter-clockwise direction.

According to some embodiments, the wafer polishing apparatusis configured to receive a wafer or stack of wafers at the holding unit. According to some embodiments, the holding unitand the four polishing head unitsare configured to transfer a wafer from the holding unitto the undersides of the four polishing head unitslocated at loading station LD. According to some embodiments, the wafer polishing apparatusis configured to rotate the four support structuresin a clockwise or counterclockwise direction to transport the wafers from station LD, to stations A, B, and C, and back to station LD. According to some embodiments, a loaded wafer is polished at stations A, B, and C. According to some embodiments, a loaded wafer is polished at one of stations A, B, or C. According to some embodiments, a loaded wafer is polished at one or more of stations A, B, or C.

According to some embodiments, the three platesare configured to rotate about an axis, thereby rotating the three wafer polishing padsthat are secured to the three plates. According to some embodiments, the three slurry injection unitsare configured to supply slurry to the three wafer polishing pads. According to some embodiments, the four polishing head unitsare configured to press wafers against the three wafer polishing pads. According to some embodiments, the four polishing head unitsare configured to rotate the wafers against the three wafer polishing pads. According to some embodiments, the wafer polishing apparatusis configured to pivot the three support armsand rotate the three polishing pad conditioning apparatusesto condition the three wafer polishing pads.