WO2015187338A1 - Coulée centrifuge de tampons de polissage polymères - Google Patents

Coulée centrifuge de tampons de polissage polymères Download PDF

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Publication number
WO2015187338A1
WO2015187338A1 PCT/US2015/030903 US2015030903W WO2015187338A1 WO 2015187338 A1 WO2015187338 A1 WO 2015187338A1 US 2015030903 W US2015030903 W US 2015030903W WO 2015187338 A1 WO2015187338 A1 WO 2015187338A1
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WO
WIPO (PCT)
Prior art keywords
mold
pad
layer
polymer mixture
polymer
Prior art date
Application number
PCT/US2015/030903
Other languages
English (en)
Other versions
WO2015187338A9 (fr
Inventor
Gary Quigley
Jorge Craik
Kevin Song
Koli Holani
Long Nguyen
Matt Richardson
Pepito Galvez
Peter Mckeever
Thomas West
Original Assignee
Thomas West, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US14/297,177 external-priority patent/US10722997B2/en
Application filed by Thomas West, Inc. filed Critical Thomas West, Inc.
Priority to SG11201610107TA priority Critical patent/SG11201610107TA/en
Priority to KR1020167037075A priority patent/KR102376599B1/ko
Publication of WO2015187338A1 publication Critical patent/WO2015187338A1/fr
Publication of WO2015187338A9 publication Critical patent/WO2015187338A9/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B24B37/11—Lapping tools
    • B24B37/20—Lapping pads for working plane surfaces
    • B24B37/22—Lapping pads for working plane surfaces characterised by a multi-layered structure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D11/00—Constructional features of flexible abrasive materials; Special features in the manufacture of such materials
    • B24D11/001—Manufacture of flexible abrasive materials
    • B24D11/003—Manufacture of flexible abrasive materials without embedded abrasive particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D18/00—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for
    • B24D18/0009—Manufacture of grinding tools or other grinding devices, e.g. wheels, not otherwise provided for using moulds or presses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C41/00—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor
    • B29C41/02—Shaping by coating a mould, core or other substrate, i.e. by depositing material and stripping-off the shaped article; Apparatus therefor for making articles of definite length, i.e. discrete articles
    • B29C41/04—Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould
    • B29C41/042—Rotational or centrifugal casting, i.e. coating the inside of a mould by rotating the mould by rotating a mould around its axis of symmetry

Definitions

  • the present disclosure relates generally to polishing pads. More specifically, the present disclosure relates to methods and systems for casting polymer polishing pads using a centrifugal caster.
  • Polishing is a process step which is commonly used in the manufacture of semiconductor, hard disk drive and optical products.
  • the polishing process generally consists of rubbing a substrate against a polymer pad, or vice versa.
  • a chemical solution usually containing fine particles (the slurry), is present at the interface between the substrate and the polymer pad.
  • a method includes rotating a mold about an axis.
  • the mold confines a polymer mixture that includes at least a high density material and a low density material.
  • the method also includes separating the polymer mixture under an influence of a centrifugal force into a first layer that includes the high density material and a second layer that includes the low density material.
  • the mold includes a cylinder, and the axis is a central axis of the cylinder.
  • the cylinder includes a centrifugal caster adapted to rotate.
  • the centrifugal caster defines a cylindrical interior space.
  • the method optionally includes forming a multilayer polishing pad that includes at least two distinct layers after the polymer mixture has separated and reacted.
  • the first layer is adapted to be used as a polish pad of the multilayer polishing pad
  • the second layer is adapted to be used as a sub-pad of the multilayer polishing pad.
  • the low density material includes microspheres that enclose a gas.
  • the method includes introducing a second polymer mixture into the mold and further rotating the mold.
  • the second polymer mixture includes a single density material or at least a second high density material and a second low density material. If the second polymer mixture is a single density material, it may be may be harder, softer, thicker or thinner than either of the first or second layers, individually or combined.
  • the layer formed by the second polymer mixture may act as a polish surface or a sub-pad.
  • the second polymer mixture separates under the influence of the centrifugal force during the further rotating operation into a third layer including the second high density material and a fourth layer including the second low density material.
  • the third layer is interposed between the second layer and the fourth layer.
  • the second low density material includes microspheres that enclose a gas.
  • the method includes, before introducing the second polymer mixture into the mold, placing a layer of polyester, textile, or conductive material on the second layer to form an additional layer on top of the second layer.
  • the method may include, before introducing the second polymer mixture into the mold, spraying a liquid onto a surface of the second layer.
  • the liquid is an adhesive and/or a conductive layer.
  • a layer of polyester, textile or a conductive material is placed on the second layer. Prior to this step a liquid may be dispensed onto the surface of the second layer. No additional layers are added.
  • a dispenser is adapted to introduce the polymer mixture into the centrifugal caster.
  • the method optionally includes heating the mold during at least a portion of a time of the rotating.
  • the method optionally includes treating a surface of the mold with a mold release agent prior to dispensing the polymer mixture into the mold.
  • the method includes forming a texture on a surface of the mold and/or using a liner or insert.
  • the liner or insert will contain texture.
  • the liner or insert placed on the surface of the mold is referred to as the bottom liner or insert.
  • a second liner or insert maybe positioned in the mold after the polymer mixture has been applied to the mold and/or bottom liner or insert. This second liner or insert is referred to as the top liner or insert.
  • the texture of the liners or inserts is adapted to form a groove texture on a working surface of the multilayer polishing pad, a perforation delineating an outer edge of the multilayer polishing pad, and/or a roughened texture on a backside of a pad surface opposite the working surface to improve adhesion between the pad surface and an adhesive and/or a sub-pad.
  • the method includes positioning at least one window on a surface of the mold prior to introducing the polymer mixture into the mold.
  • a system for manufacturing a multilayer polishing pad includes a mold having a rotational axis.
  • Substantially all points on a bottom surface of the mold are substantially equidistant from the rotational axis throughout a revolution about the rotational axis.
  • the mold is adapted to confine a polymer mixture when the mold is rotating.
  • the system further includes a dispenser adapted to introduce the polymer mixture into the mold.
  • the system includes a mandrel insertable along the central axis for positioning a solid insert on a surface of a top layer of the polymer mixture in the interior space.
  • the solid insert is polyester, textile, conductive material, and/or a top liner for imparting a texture to a surface of the polymer mixture.
  • the system includes a sprayer for spraying a liquid into an interior of the mold.
  • the liquid is a mold release agent, an adhesive, and/or a conductive layer.
  • the system includes a heater for heating the mold during at least a portion of a time of the rotating and reacting of the polymer mixture.
  • FIG. 1 is a cross section schematic diagram illustrating a centrifugal casting system, according to an example embodiment.
  • FIG. 2 is a cross section schematic diagram illustrating the centrifugal caster shown in FIG. 1 after an example polymer mixture has undergone phase separation and formed two distinct layers, according to an example embodiment.
  • FIG. 3 is a schematic diagram illustrating a cross section of the example centrifugal caster shown in FIG. 2 and showing an example bottom liner or insert and polyurethane casting, according to an example embodiment.
  • FIG. 4 is a schematic diagram illustrating a cross section of an example multi-layer polymer pad, according to an example embodiment.
  • FIG. 5 is a schematic diagram illustrating a cross section of the example centrifugal caster and showing a top liner or insert and
  • polyurethane casting according to an example embodiment.
  • FIG. 6 is a cross section schematic diagram illustrating the centrifugal casting system with an example mold insert lining the interior wall (bottom liner/insert) of an example drum of the example centrifugal caster, according to an example embodiment.
  • FIG. 7 is a schematic diagram illustrating a cross section of the example drum and showing an example mold insert and window, according to an example embodiment.
  • FIG. 8 is a schematic diagram illustrating an example rotational casting system including an example centrifugal caster, according to an example embodiment.
  • FIG. 9 is a flow chart illustrating an example method for making a multilayer polishing pad, according to an example embodiment.
  • FIG. 10 is a flow chart illustrating an alternative example method for making a multilayer polishing pad, according to an example
  • the present technology relates generally to polish pads. More specifically, the present disclosure provides a method for making solid multilayer polymer polish pads.
  • CMP Chemical Mechanical Planarization
  • polish pads used for CMP employ open cell polyurethane materials.
  • fiber impregnated with a polymer, or polymers combined with abrasives can be utilized.
  • the surface of such pads may contain a micro texture.
  • the micro texture is to the polish performance of the pad. The micro texture is maintained by the
  • a solid polymer polish pad contains no inherent micro structure, and instead relies on the conditioning process during use to impart a micro texture to the pad surface.
  • the formulation used for the solid polymer pad is key in terms of compatibility with conventional conditioning processes.
  • the polymer pad typically includes a single layer solid polymer material or multiple layers of solid polymer material stacked on each other. Alternatively, some non-solid layer(s) may be used. The layers are bonded to each other using adhesive.
  • the layer that polishes is referred to as the polish layer, top pad or pad surface.
  • the top pad material itself is typically based upon polyurethane, though a wide range of other polish pad materials are viable, as described earlier.
  • Flow channels may be provided on the polish surface of the polymer polish pad. These flow channels have many functions but are primarily used to improve slurry flow to ensure the presence of slurry on all areas of the polymer polish pad.
  • the flow channels also result in higher contact pressure during the polishing process which can increase the rate of polish, or planarization, of the substrate. Also, the flow channels can be used to accelerate pad rinsing after the polish step has finished. These flow channels can be considered as macro texture on the polish pad. The macro texture is typically applied prior to use of the polymer polish pad.
  • a micro texture is formed on the surface of the polymer polish pad.
  • the process of forming such a micro texture is commonly referred to as conditioning.
  • conditioning By conditioning the pad surface at such a high frequency, it is possible to maintain a consistent micro texture on the polymer pad surface. This is important to maintain consistent polish performance because the micro texture creates mini flow channels for the slurry between the polymer pad surface and the substrate.
  • the afore-mentioned flow channels and the micro texture form a symbiotic relationship in ensuring good fluid dynamics during polishing.
  • Conditioning of the polymer polish pad is typically performed using a diamond conditioner. Diamond size, shape, density and protrusion level are altered to produce different diamond conditioner capabilities.
  • thermoplastic injection molding (2) thermoset injection molding (often referred to as “reaction injection molding” or “RIM”); (3) thermoplastic or thermoset injection blow molding; (4) compression molding; and (5) a similar process in which a material is positioned and solidified.
  • RIM reaction injection molding
  • compression molding (4) compression molding
  • Centrifugal casting involves pouring a liquid into a cylindrical mold spinning about its axis of symmetry. The mold is kept rotating until the material has solidified.
  • the present technology provides for the use of a centrifugal caster employed to manufacture polymer polish pads.
  • a centrifugal caster is described as an open cast method.
  • Centrifugal casting technology is used for manufacturing iron pipes, bushings, wheels, and other parts possessing axial symmetry.
  • a permanent mold is rotated about its axis at high speeds (300 to 3000 RPM) as the molten metal is poured.
  • the molten metal is centrifugally thrown towards the inside mold wall, where it solidifies after cooling.
  • Typical metal materials that can be cast with this process are iron, steel, stainless steels, and alloys of aluminum, copper and nickel.
  • Centrifugal casting may also be employed for the manufacture of polymer parts.
  • polyurethane timing belts for special applications are produced using centrifugal casting.
  • the belts have special coatings and reinforcing to suit specific transmission applications.
  • the belts are one piece molded and are formed using centrifugal casting process and high performance polyurethane.
  • the belts have embedded steel, Kevlar®, polyester, stainless steel or glass fiber reinforcing.
  • the belts are used with linear drives in applications like packaging, sorting, and assembly machines.
  • the preparation of the raw materials needed to manufacture a polymer polish pad requires significant control to ensure consistent raw material ratios are input to the mixture.
  • the raw materials need to be heated separately before mixing.
  • the raw materials preferably are mixed thoroughly to result in even dispersion within the mixture.
  • the materials may foam upon mixing.
  • the mixture can be passed through a system to eliminate the foam (though this process should not be confused with adding foam to a polymer mixture, as discussed below).
  • the material then needs to be transferred to a mold for reacting. This process can be further complicated when the pot life (i.e., the time until the polymer sets) of the mixture is short. If the pot life is exceeded, then the mixture will begin to gel and may no longer be formed to the desired shape.
  • the period of time during which a reacting polymeric compound remains suitable for its intended use after having been mixed with a reacting initiating agent is the "pot life".
  • the gel point (or gel time) refers to the stage at which a liquid begins to exhibit pseudo-elastic properties. After a polyurethane has gelled (also referred to as reacted), the material may be solidified sufficiently to be removed from a mold or centrifuge (if any), while still retaining its shape.
  • a solid polymer polish pad is produced using centrifugal casting.
  • This process involves introducing the polymer mixture, which is a liquid, into a large rotating drum.
  • the centrifugal force propels the polymer mixture against the inner surface of the drum, and when the polymer mixture reacts and becomes solid, a rectangular belt of solid polymer is obtained.
  • the polymer mixture is introduced into the spinning drum of the centrifugal caster, the polymer mixture material fans out and adheres to the walls of the drum.
  • the polymer mixture has reacted and solidified, there are substantially no pores across a majority of the material cross section. Any pores present will be isolated to the surface of the sheet, which is opposite or furthest from the interior wall of the drum, and therefore are easily eliminated during formation, preparation and/or conditioning.
  • Centrifugal casting to make a solid polymer sheet enables the manufacture of a polish pad that is free of voids.
  • the process can be adjusted to ensure that the total thickness variation (TTV) of the material will be very small.
  • TTV total thickness variation
  • the temperature and speed (in rotations per minute, or RPM) of a centrifugal caster used to make a polish pad can be altered depending on the desired pad characteristics and the type of polymer mixture being used.
  • the centrifugal casting system and method provided herein allows the formation of a thin sheet of solid polymer with low TTV.
  • a thin sheet of polymer for example, polyurethane
  • the centrifugal casting method provided herein ensures the formation of a multilayer polish pad with a solid layer and a porous layer with densely packed microspheres using phase separation in a centrifugal casting system.
  • Phase separation can be induced when mixtures contain fillers, abrasives, and/or fibers.
  • the microspheres are typically plastic and vary in size, be expandable or non-expandable, have an enclosed gas or blowing agent, and/or be solid or hollow.
  • the present technology enables the formation of a multilayer polish pad with different polymer formulations by adding adhesives (e.g., pressure sensitive adhesive) in between the layers. Furthermore, the present technology can be used to induce predetermined or desirable anisotropic chain structure in the polymer sheets.
  • adhesives e.g., pressure sensitive adhesive
  • the porous layer of the polish pad (or sub-pad) is advantageous for polishing because of the compressibility of the material, which comes from the densely packed pores. Additionally, the closed cell pore structure prevents wicking of process fluids into the sub-pad, which may impact polish performance.
  • An inner surface of the caster is smooth, or alternatively a texture is used to add grooves or channels to a working surface of the polish pad, and/or to improve the performance of the adhesive used in the polish pad construction.
  • Grooves may be added to the polish pad during or after the casing process, and may be made on a surface formed opposite the caster wall. Grooves are useful during use of the polish pad during a CMP operation to promote the flow of slurry.
  • a pad is formed with multiple layers, and then some or all of these layers are revealed in the groove area through the grooving process. For example, the groove reveals a different structure at the groove bottom, which is distinct from the groove sides and top layer.
  • the newly exposed layer at the bottom of a groove in some cases may be harder, softer, and/or have pores to facilitate slurry flow.
  • Different groove cross-sectional shapes, different layers of materials exposed in the grooves, and/or different groove geometries are utilized to impact the flow of slurry and/or to alter the removal rate for a polish pad.
  • Heating during centrifugal casting is performed by heating elements that surround or are adjacent to the casting drum, which heat the drum and/or the air in the drum. Typically, the drum is pre-heated prior to introduction of the polymer mixture. Additional processes can also be implemented during the casting operation to improve product
  • micro texture in the pad material enhances the polish performance of the polish pad. Such micro texture should be consistent within the pad material to prevent inconsistent polish
  • a solid pad relies on the micro texture introduced during casting or conditioning. Should a pore or pores be present in the pad material, then this leads to an increased level of polish rate. This increased level of polish rate is in some cases not sustainable because the pores are not consistently present in the layer. For this reason it is important that a solid polish pad contain few or no pores. Efforts to manufacture solid polymer pads without pores have been largely ineffective. By contrast, the use of a centrifugal caster overcomes the issues with polymer mixtures, while ensuring void-free polymer sheets, even with short pot life polymer mixtures.
  • the centrifugal caster reduces or eliminates pores or voids in the polymer sheet because centrifugal force drives the polymer mixture material to the interior wall of the caster, while any pores or voids migrate to the opposite surface since the pores or voids are lighter than the polymer mixture.
  • bubbles and/or pores migrate to the surface during hardening of the polymer, and may remain on the surface after hardening. These bubbles and/or pores can be removed by thinning the interior surface of the belt, which is used as the working surface of the polishing pad. This thinning typically requires the removal of between 1 and 4 thousandths of an inch, or alternatively up to 15/1000 of an inch.
  • Centrifugal casting of solid polymer sheet provides the unexpected benefit of generating an exceptionally flat polymer sheet.
  • the polymer polish pad formed by centrifugal casting is substantially or completely free of pores or voids, and is substantially uniform in thickness.
  • a polymer sheet is formed using a short pot life mixture, while also being substantially or completely free of pores. Consequently, a high manufacturing throughput is achieved utilizing the present technology
  • CMP pad manufacturing may include the formation of a cake or ingot of solid polymer that is sliced, which requires substantial uniformity from top to bottom, which is difficult.
  • the solid polymer produced is extremely flat and only a bare minimum thicker than the ultimate thickness of the pad.
  • a very large belt is produced that can be used to make many top pads (or sub-pads) by cutting or punching by any appropriate method, which enables a high throughput along with a very consistent product and substantially nonexistent porosity.
  • the example method disclosed herein is utilized to form two or more separate and distinct layers by casting and gelling sequentially two or more different polymer mixtures. This embodiment is not possible in closed cast systems.
  • a reinforced pad may be formed using the present technology by placing a fiber network on the partially reacted initial polymer sheet and subsequently forming an additional layer on top of the network.
  • An example variation of the present technology utilizes improved adhesion between adhesive (pressure sensitive adhesive or hot melt adhesive) and polymer pad by making the drum interior slightly rough. Poor adhesion can result in pad delamination during polishing. This will result in damage to the polisher, scrap of the substrate being polished and significant downtime for the polisher, which will impact efficiency.
  • FIG. 1 is a schematic diagram illustrating spin casting system 100 including centrifugal caster 102 and polymer dispenser 104.
  • Polymer dispenser 104 contains polymer mixture 106.
  • Polymer dispenser 104 includes a mixing apparatus and includes jackets, with or without heating elements having conduits for heated fluid to flow through, and/or electrical heating elements.
  • Polymer mixture 106 is a polymer mixture that will phase separate into multiple layers only under centrifugal force and will not phase separate under ambient, non-pressurized conditions.
  • Polymer mixture 106 may be one polyurethane mixture with microspheres added in to change the density of the mixture.
  • polymer mixture 106 contains more than one polymer and includes a polymer composite created within centrifugal caster 102 by adding foam in between the polymer mixtures.
  • foam in the context of polishing pads means a polyurethane (also referred to as a PU) pad that has a closed cell or open cell structure.
  • the cells could be microspheres surrounded by PU, voids surrounded by PU or open voids through the PU.
  • a porous pad material is referred to as a foamed pad.
  • Two methods for making a foam product other than by adding microspheres are 1) adding a blowing agent to the polyurethane mixture, and 2) introducing a gas into the mixture (for example, N2 or CO2).
  • Polymer mixture 106 is streamed from polymer dispenser 104 into pouring path 108 that directs polymer mixture 106 into drum 110 of centrifugal caster 102 while drum 110 is spinning around axis 112 in rotational direction 114. Polymer mixture 106 spreads out to form polymer sheet 116 on an interior surface of drum 110 due to centrifugal force.
  • polymer sheet 116 is cylindrical in shape.
  • Drum 110 spins, and has a diameter such that at whatever rotational velocity drum 110 turns, the centrifugal force experienced by polymer mixture 106 after introduction into drum 110 is sufficient to create a uniform thickness of polymer sheet 116, and to additionally cause phase separation. Phase separation occurs under centrifugal force and causes polymer mixture 106 to separate into at least two layers of polymer, and/or a pure polymer layer and a polymer layer infused with microspheres.
  • drum 110 is heated.
  • Drum 110 may have a smooth interior drum face, or alternatively drum 110 has a textured drum face that improves the performance of adhesives used in the polishing pad, that provides grooves to a surface of a polish pad made according to the method, and/or that facilitates the separation and/or forming of a polish pad from a reacted and casted polymer sheet formed by the method.
  • FIG. 2 is a schematic diagram illustrating centrifugal caster 102 after polymer mixture 106 has undergone phase separation and formed two distinct layers.
  • polymer mixture 106 phase separates into two distinct layers: soft polymer layer 200 and dense polymer layer 202.
  • the centrifugal force forces the polymer towards one side of polymer sheet 116, and causing the microspheres to rise to a surface of polymer sheet 116 since they are less dense than the polymer.
  • This phase separations creates a denser layer and a porous layer.
  • Dense polymer layer 202 is the denser layer and forms the hard pad of the polishing pad.
  • Dense polymer layer 202 is a layer of solid polyurethane.
  • Soft polymer layer 200 is the porous layer filled with densely packed microspheres and forms the sub-pad of the polishing pad.
  • Dense polymer layer 202 is the inner layer that interfaces with the interior of drum 110.
  • Polymer sheet 116 may be thinned either before or after forming an outline of the polymer pad to make a groove pattern on the surface of polymer sheet 116. Similarly, the surface of polymer sheet 116 is
  • a third layer of the same or different polymer or another material is cast on top of polymer sheet 116 in order to make a three (or more) layer polymer pad. Subsequent layers are formed, if necessary, by adding the same or different polymer layers as described.
  • FIG. 3 is a schematic diagram illustrating a cross section of centrifugal caster 102 and showing insert 300 and polymer sheet 116 with dense polymer layer 202 and soft polymer layer 200.
  • Drum 110 spins around axis 112 in rotational direction 114.
  • Insert 300 lines the interior wall of the drum 110.
  • insert 300 is a mold release agent that is a permanent (e.g., Teflon®), semi-permanent (e.g., Teflon® spray), or temporary coating in the centrifugal caster 102 that facilitates release of the solid polymer after casting.
  • the interior surface of drum 110 is in some cases sprayed with a Teflon® coating after a certain number of castings, for example after 20 castings.
  • insert 300 is a mold release sheet made from High-density polyethylene (HDPE), Thermoplastic, Polytetrafluoroethylene (PTFE) or Silicone. In certain instances, insert 300 is replaced infrequently, for example once every few months.
  • HDPE High-density polyethylene
  • PTFE Polytetrafluoroethylene
  • Silicone Silicone
  • insert 300 is grooved to form groove patterns on the surface of polymer sheet 116, which are formed on dense polymer layer 202.
  • insert 300 has channels for the purpose of forming different types of polishing pads.
  • FIG. 4 is a schematic diagram illustrating a cross section of polymer pad 400.
  • drum 110 is stopped and polymer sheet 116 containing the two layers is removed from drum 110.
  • Removing polymer sheet 116 includes cutting polymer sheet 116 along a line parallel to axis 112, causing polymer sheet 116 to change from a cylindrical belt shape to a rectangular shape. Alternatively, the cutting process may be performed external to the centrifugal caster.
  • Polymer pad 400 is cut out or punched out of polymer sheet 116.
  • the removed polymer pad 400 includes sub-pad 402 and hard pad 404. Hard pad 404 is formed from dense polymer layer 202 while sub- pad 402 is formed from soft polymer layer 200.
  • Both hard pad 404 and sub- pad 402 can be used for polishing.
  • the solid side (hard pad 404) is conventionally used for polishing
  • the porous side (sub-pad 402, though for this use it would not be a sub-pad) may be used and provides uniform polishing due to the dense packing of microspheres.
  • Sub-pad 402 has pores that are packed extremely tight allowing for more compressibility, and also prevents wicking.
  • the surfaces of polymer sheet 116 are thinned to create a more uniform thickness on both layers and/or to remove surface imperfections.
  • a sub-pad may be added on either side of this assembly, before or after forming an outline and/or thinning.
  • FIG. 5 is a schematic diagram illustrating a cross section of centrifugal caster 102 and showing internal insert 500 and polymer sheet 116 with dense polymer layer 202 and soft polymer layer 200.
  • Internal insert 500 is a sheet made from HDPE, Thermoplastic, PTFE or Silicone and has groove patterns similar to insert 300. Internal insert 500 lays against polymer sheet 116 and is placed within drum 110 by hand or with the use of a mandrel. With a mandrel, internal insert 500 is wrapped around the mandrel to ease the placement in drum 110.
  • drum 110 is slowed to a lower RPM while the mandrel with internal insert 500, rotating at the same RPM as drum 110, is inserted into the center of drum 110 along axis 112.
  • the RPM of drum 110 is increased back to the original rotational speed, creating a strong enough centrifugal force that pulls internal insert 500 from the mandrel towards polymer sheet 116.
  • FIG. 6 is a schematic diagram illustrating spin casting system 100 with mold insert 600 lining the interior wall of drum 110 of centrifugal caster 102.
  • Mold insert 600 be a sheet made from Teflon®, HDPE,
  • Mold insert 600 has at least one mold of a polishing pad, with the number of molds depending on the size of drum 110 and the size of the polishing pad.
  • the mold of mold insert 600 may be a single mold or a plurality of molds, which are fixed or removable and which have a fixed or a variable distance from axis 112 to vary an amount of centrifugal force experienced by the polymer during the casting process.
  • the mold or molds of mold insert 600 form an outline of a CMP pad, and have a textured surface as discussed above in regard to drum 110, insert 300, and/or internal insert 500.
  • mold insert 600 has four molds on the sheet that lines drum 110, thus potentially producing four polishing pads in one casting.
  • polymer mixture 106 is poured into each mold individually, which eliminates the need to cut or punch out the polishing pad from a polymer sheet. Through this embodiment method, waste can be reduced.
  • FIG. 7 is a schematic diagram illustrating a cross section of drum 110 and showing mold insert 600 and window 700.
  • Window 700 is a transparent material (e.g., urethane) that enables the implementation of optical endpoint technology. Window 700 is placed in the molds of mold insert 600 before the polymer mixture is channeled into the individual molds. The polymer mixture surrounds the sides of window 700.
  • window 700 can either be incorporated into the polishing pad as a window, or be separated from the polishing pad to leave a space for a window to be inserted into the polishing pad.
  • FIG. 8 is a schematic diagram illustrating multi-axis rotational casting system 800 including casting mold 802.
  • Casting mold 802 includes two mold sections: top mold part 804 and bottom mold part 806. Top and bottom are used herein for reference purposes only, and not to limit the exemplary embodiments. Therefore, top mold part 804 could be positioned in a bottom area, and bottom mold part 806 could be positioned in a top area.
  • Polymer mixture 808 is dispensed into one or both of top mold part 804 and bottom mold part 806 while separated, and then top mold part 804 and bottom mold part 806 is joined as shown in FIG. 8.
  • Interior space 810 of casting mold 802 may include an air space, or alternatively is completely filled with polymer mixture 808.
  • Top mold part 804 and bottom mold part 806 are sealed together prior to casting to form casting mold 802.
  • Casting mold 802 is rotated around axis 812 in direction 814 and around axis 816 in direction 818.
  • Axis 812 is shown bisecting casting mold 802, but
  • axis 816 is shown offset from casting mold 802, but alternatively bisects casting mold 802.
  • One or both of the rotations is conducted initially and at a slower rate in order to promote coverage of the interior surface of casting mold 802.
  • a vibration in one or more directions is used additionally or alternatively to promote wetting of the mold surface.
  • One or both of the rotations is at a higher rotational velocity in order to promote the movement of
  • FIG. 9 is a process flow diagram showing a method 900 according to the present technology using polyurethane. However, the method is also applicable to other polymers, as discussed herein. As shown in FIG. 9, the method 900 commences at operation 902, which indicates to mix
  • the flow proceeds to operation 904, which indicates to dispense the hybrid mixture into an interior space of a cylinder.
  • operation 904 indicates to rotate the cylinder about a central axis, the cylinder enclosing in the interior space the hybrid mixture until the mixture phase separates into two distinct layers.
  • operation 908 indicates to heat the cylinder to a temperature between 140 and 212 degrees Fahrenheit during at least a portion of a time of the rotating operation.
  • operation 910 which indicates to form the polishing pad from the polyurethane sheet formed after the hybrid mixture has separated into two layers and has reacted.
  • the process flow ends after operation 910.
  • a polymer (for example a polyurethane, also referred to as PU) casting system involves mixing more than one polymer together forming a polymer composite.
  • foam is added in between to separate the different polymer mixtures formed using a centrifugal caster.
  • FIG. 10 process flow diagram showing an alternative method 1000 in forming multilayer polishing pads according to the present technology using polyurethane.
  • the method is also applicable to other polymers, as discussed herein.
  • the method 1000 may commence at operation 1002, which indicates to dispense a composite mixture into an interior space of a cylinder. From operation 1002, the flow proceeds to operation 1004, which indicates to rotate the cylinder about a central axis, the cylinder enclosing in the interior space the composite mixture. From operation 1004, the flow proceeds to operation 1006, which indicates to heat the cylinder to a temperature between 140 and 212 degrees Fahrenheit during at least a portion of a time of the rotating operation.
  • the flow proceeds to operation 1008, which indicates to dispense a harder polyurethane mixture into an interior space of a cylinder after the composite mixture has gelled. From operation 1008, the flow proceeds to operation 1010, which indicates to rotate and heat the cylinder until the harder polyurethane and the composite mixture has reacted forming a polyurethane sheet with two layers. With the composite mixture solidified into a gel (also referred to as reacted), prior to dispensing the harder polyurethane, the harder polyurethane layer would chemically bond with the softer polyurethane layer without the need for pressure sensitive adhesive (PSA) to bind the two layers. From operation 1010, the flow proceeds to operation 1012, which indicates to form the polishing pad from the polyurethane sheet containing the two layers. The process flow ends after operation 1012.
  • PSA pressure sensitive adhesive
  • the harder polyurethane mixture is dispensed into the cylinder and gels before dispensing the composite mixture into the cylinder.
  • a thin layer is installed or formed on the surface of the softer polyurethane layer.
  • the thin layer is made from polyester, textile, or conductive material.
  • the thin layer of polyester, nylon, textile, or conductive material is woven or non-woven, and can be on either side or encapsulate the polyurethane sheet.
  • the conductive material also coats (e.g., liquid, sprayed, or aerosolized) the polyurethane sheet prior to forming the polishing pad.
  • a multi-layer polymer pad is formed in a single or multiple castings.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Polishing Bodies And Polishing Tools (AREA)

Abstract

L'invention porte sur un procédé pour réaliser un tampon de polissage multicouche, lequel procédé consiste en la rotation d'un cylindre autour d'un axe central. Le cylindre renferme dans un espace intérieur un mélange polymère unique qui se sépare en phases sous une force centrifuge. Le procédé met également en œuvre la formation du tampon de polissage à partir d'au moins une partie d'un polymère formé après que le mélange polymère a réagi. Le procédé met en œuvre la formation d'au moins deux couches distinctes dans le tampon de polissage par coulée et gélification en séquence d'au moins deux polymères différents.
PCT/US2015/030903 2014-06-05 2015-05-14 Coulée centrifuge de tampons de polissage polymères WO2015187338A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
SG11201610107TA SG11201610107TA (en) 2014-06-05 2015-05-14 Centrifugal casting of polymer polish pads
KR1020167037075A KR102376599B1 (ko) 2014-06-05 2015-05-14 고분자 연마 패드의 원심 성형법

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US14/297,177 US10722997B2 (en) 2012-04-02 2014-06-05 Multilayer polishing pads made by the methods for centrifugal casting of polymer polish pads
US14/297,177 2014-06-05

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WO2015187338A1 true WO2015187338A1 (fr) 2015-12-10
WO2015187338A9 WO2015187338A9 (fr) 2016-11-17

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SG (1) SG11201610107TA (fr)
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US10022842B2 (en) 2012-04-02 2018-07-17 Thomas West, Inc. Method and systems to control optical transmissivity of a polish pad material
US10722997B2 (en) 2012-04-02 2020-07-28 Thomas West, Inc. Multilayer polishing pads made by the methods for centrifugal casting of polymer polish pads
TWI717183B (zh) * 2020-01-03 2021-01-21 銓科光電材料股份有限公司 晶圓拋光墊
US11090778B2 (en) 2012-04-02 2021-08-17 Thomas West, Inc. Methods and systems for centrifugal casting of polymer polish pads and polishing pads made by the methods
EP4353411A1 (fr) * 2022-10-13 2024-04-17 Ernst-Abbe-Hochschule Jena Outil d'enlèvement de matière et son procédé de fabrication

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TWI717183B (zh) * 2020-01-03 2021-01-21 銓科光電材料股份有限公司 晶圓拋光墊
EP4353411A1 (fr) * 2022-10-13 2024-04-17 Ernst-Abbe-Hochschule Jena Outil d'enlèvement de matière et son procédé de fabrication

Also Published As

Publication number Publication date
KR20170018359A (ko) 2017-02-17
KR102376599B1 (ko) 2022-03-21
TW201607643A (zh) 2016-03-01
SG11201610107TA (en) 2017-01-27
WO2015187338A9 (fr) 2016-11-17
TWI665033B (zh) 2019-07-11

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