KR102376599B1 - Centrifugal casting of polymer polish pads - Google Patents

Abstract

According to the present invention, a method of manufacturing a multilayer polishing pad includes rotating a cylinder about a central axis. The cylinder traps a single polymer mixture in an interior space that phase-separates under centrifugal force. The method also includes forming a polishing pad from at least a portion of the polymer formed after the polymer mixture has reacted. The method includes forming at least two separate layers in a polishing pad by molding and subsequently gelling at least two different polymers.

Description

Centrifugal casting of polymer polish pads

[0001] The present invention relates generally to a polishing pad. More particularly, the present invention relates to a method and system for forming a polymer polishing pad using a centrifugal caster.

BACKGROUND Polishing (also referred to as 'planarization') is a processing process commonly used in the manufacture of semiconductors, hard disk drives, and optical products. The polishing process generally consists of rubbing the substrate against a polymer pad, or rubbing the polymer pad against the substrate. Typically, a chemical solution containing fine particles (slurry) exists at the interface between the substrate and the polymer pad.

According to the present invention, there is provided a method comprising the step of rotating a mold about an axis. The mold encloses a polymer mixture comprising a high-density material and a low-density material. The method also comprises the step of separating the polymer mixture under the influence of centrifugal force into a first layer comprising a high-density material and a second layer comprising a low-density material. The mold comprises a cylinder, the axis being the central axis of the cylinder. In some embodiments, the cylinder includes a rotatable centrifugal caster. The centrifugal caster has a cylindrical interior space.

The method optionally includes forming a multilayer polishing pad comprising two or more separate layers after the polymer mixture has been separated and reacted. The first layer is used as a polishing pad of the multi-layer polishing pad, and the second layer is used as a sub-pad of the multi-layer polishing pad. A low-density material contains microspheres surrounding a gas.

In some embodiments, the method comprises injecting a second polymer mixture into the mold and further rotating the mold. The second polymer mixture comprises a single density material, or a second high density material and a second low density material. If the second polymer mixture is a single density material, the second polymer mixture may be harder, softer, thicker, or thinner than if the first or second layers were individually or combined. The layer formed by the second polymer mixture may act as a polishing surface or sub-pad. The second polymer mixture is separated under the influence of centrifugal force into a third layer comprising a second high-density material and a fourth layer comprising a second low-density material during the step of further rotating the mold. The third layer is located between the second and fourth layers. The second low density material includes microspheres surrounding the gas.

In some embodiments, the method comprises, prior to injecting the second polymer mixture into the mold, a polyester layer, a fabric layer, or a layer of conductive material on the second layer to form an additional layer on the second layer. positioning step. The method may include spraying a liquid on the surface of the second layer prior to injecting the second polymer mixture into the mold. The liquid is an adhesive and/or a conductive layer. Optionally, a polyester layer, a fabric layer or a layer of conductive material is positioned on the second layer. Prior to this step, a liquid may be applied to the surface of the second layer. Also, no additional layers may be added.

A dispenser injects the polymer mixture into a centrifugal caster. The method optionally includes heating the mold for some or all of the time during which the rotating step occurs. The method optionally includes treating the surface of the mold with a mold release agent before injecting the polymer mixture into the mold.

In some embodiments, the method includes forming a texture on the surface of the mold, and/or on a liner or insert. The liner or insert will comprise tissue. A liner or insert placed on the surface of the mold is referred to as a bottom liner or insert. Also, after the polymer mixture has been applied to the mold and/or the lower liner or insert, a second liner or insert may be placed in the mold. This second liner or insert is referred to as a top liner or insert. The texture of the liner or insert enhances the grooving texture on the working surface of the multilayer polishing pad, perforations formed in the outer rim of the multilayer polishing pad, and/or adhesion between the adhesive and/or sub-pad and the pad surface opposite the working surface. to form a rough texture on the back side of the pad surface.

The method includes positioning one or more windows on the surface of the mold prior to pouring the polymer mixture into the mold.

In accordance with the present invention, a system for manufacturing a multilayer polishing pad is provided. The system includes a mold having an axis of rotation. Substantially all points on the bottom surface of the mold are substantially equidistant from the axis of rotation during rotation about the axis of rotation. The mold traps the polymer mixture while the mold is rotating. The system further comprises a dispenser for dispensing the polymer mixture into the mold.

Optionally, the system comprises a mandrel insertable along a central axis for positioning the solid insert on the surface of the uppermost layer of the polymer mixture in the interior space. A solid insert is a top liner for imparting texture to the surface of a polyester, textile, conductive material, and/or polymer mixture.

The system includes a nebulizer that sprays a liquid into the interior of the mold. The liquid is a mold release agent, an adhesive, and/or a conductive layer.

In some embodiments, the system includes a heater that heats the mold for some or all of the time to rotate and react the polymer mixture.

1 is a schematic cross-sectional view illustrating a centrifugal molding system according to an exemplary embodiment.
FIG. 2 is a schematic cross-sectional view illustrating the centrifugal caster shown in FIG. 1 after an exemplary polymer mixture has undergone phase separation and formed two separate layers, in accordance with one exemplary embodiment.
3 is a schematic diagram illustrating a cross-section of the exemplary centrifugal caster shown in FIG. 2 and showing an exemplary lower liner or insert and polyurethane molding in accordance with one exemplary embodiment.
4 is a schematic diagram illustrating a cross-section of an exemplary multilayer polymer pad according to an exemplary embodiment.
5 is a schematic diagram illustrating a cross-section of an exemplary centrifugal caster in accordance with one exemplary embodiment, showing a top liner or insert and polyurethane molding.
6 is a schematic cross-sectional view illustrating a centrifugal molding system with an exemplary mold insert that forms a film on the inner wall (lower liner/insert) of an exemplary drum of an exemplary centrifugal caster, in accordance with one exemplary embodiment; .
7 is a schematic diagram illustrating a cross-section of an exemplary drum and showing exemplary mold inserts and windows in accordance with one exemplary embodiment.
8 is a schematic diagram illustrating an exemplary rotational molding system including an exemplary centrifugal caster, in accordance with one exemplary embodiment.
9 is a flow chart illustrating an exemplary method for manufacturing a multilayer polishing pad in accordance with an exemplary embodiment.
10 is a flow chart illustrating an alternative exemplary method for making a multilayer polishing pad in accordance with one exemplary embodiment.

This disclosure is susceptible to many other forms of embodiment, and with reference to the drawings, the following Detailed description will be given of individual specific embodiments. According to exemplary embodiments, the present invention relates generally to a polishing pad. More specifically, the present invention provides a method for manufacturing a solid multilayer polymer polishing pad.

Polishing in the semiconductor industry is referred to as Chemical Mechanical Planarization (CMP). Polymeric polishing pads used in CMP are usually made of closed cell polyurethane material or foamed polyurethane, although some polishing pads used in CMP use an open cell polyurethane material. use it Additionally, fibers with polymers or polymers associated with abrasives may be used. The surface of such a pad may have a microstructure. The microstructure is related to the polishing performance of the pad. The microstructure is maintained by a conditioning process. This inherent microstructure inconsistency causes variations in the polishing performance of the pad. For this reason, pad manufacturers have been working to improve their pad manufacturing processes to reduce variation in their products. In contrast, solid polymer polishing pads do not have an inherent microstructure, and instead rely on conditioning treatment during use to impart microstructure to the pad surface. The formulation used in the solid polymer pad is key in terms of compatibility with conventional conditioning treatments.

Polymeric pads typically include a single layer of solid polymer material or multiple layers of solid polymer material stacked on top of each other. Optionally, some non-solid layer(s) may be used. The layers are bonded to each other using an adhesive. The abrasive layer is referred to as the abrasive layer, the top pad or the pad surface. The top pad material itself is typically based on polyurethane, although a wide range of other polishing pad materials may be used as discussed above. Flow channels may be formed on the polishing surface of the polymer polishing pad. These flow channels have many functions, but are primarily used to improve the slurry flow to ensure the presence of slurry over the entire area of the polymer polishing pad. Further, the flow path can further increase the contact pressure during the polishing process, thereby increasing the polishing rate or the planarization rate of the substrate. Also, the flow path can be used to accelerate pad cleaning after the polishing step is finished. These passages can be considered as macroscopic structures on the polishing pad. The macrostructure is typically applied prior to use of the polymer polishing pad.

During the polishing process or in the middle of substrate polishing, a macrostructure is formed on the surface of the polymer polishing pad. This macro-organization process is commonly referred to as conditioning. By conditioning the pad surface with a short cycle, it is possible to maintain a consistent macrostructure on the polymer pad surface. Because the microstructure creates a small flow path for the slurry between the polymer pad surface and the substrate, it is important to maintain consistent polishing performance. During polishing, the aforementioned flow path and microstructure form a symbiotic relationship to ensure good fluid flowability during polishing.

Conditioning of the polymer polishing pad is typically performed using a diamond conditioner. Diamond size, shape, density and level of protrusion are varied to demonstrate different diamond conditioner performance.

A typical top pad closed cell material manufacturing process utilizes one of the following processes: (1) thermoplastic injection molding; (2) thermosetting injection molding (sometimes 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 the material is placed and solidified. These methods are demonstrated using a closed mold system.

Centrifugal molding involves pouring a liquid into a cylindrical mold that rotates about an axis of symmetry. The mold continues to rotate until the material solidifies. The present technology enables the use of centrifugal casters used to make polymer polishing pads. Centrifugal casters are described as an open forming method.

Centrifugal forming techniques are used to manufacture iron pipes, bushings, wheels, and other parts with axisymmetrical symmetry. In centrifugal forming of metal, a permanent mold rotates about the axis of the mold at a high speed (300 to 3000 RPM) as the molten metal is poured. The molten metal is thrown towards the inner wall of the mold by centrifugal force, cools and then solidifies. Typical metallic materials that can be formed with this treatment are iron, steel, stainless steel, and alloys of aluminum, copper and nickel.

Centrifugal molding can also be used in the manufacture of polymeric parts. For example, polyurethane timing belts for special applications are manufactured using centrifugal molding. Timing belts have special coatings and reinforcements to suit specific transfer applications. The timing belt is integrally molded and formed using a centrifugal molding process and high-performance urethane. Timing belts are studded with steel, Kevlar®, polyester, stainless steel or fiberglass reinforcement. Timing belts are used with linear drives in applications such as packaging, sorting, and assembly machines.

The preparation of the raw materials needed to make the polymer polishing pad requires considerable control to ensure that a consistent raw material ratio is applied to the mixture. The raw materials need to be individually heated before being mixed. Furthermore, the raw materials are, preferably, thoroughly mixed to be evenly dispersed in the mixture. Depending on the mixing technique used, the raw materials may foam when mixed. The mixture can be processed through a foam removal system (this treatment should not be confused with the process of adding foam to the polymer mixture described below). Then, the raw material needs to be transferred to the mold for reaction. This treatment can be more complicated when the pot life of the mixture (ie, time until the polymer cures) is short. If the pot life is exceeded, the mixture will begin to gel and will no longer be able to deform into the desired shape.

The period during which the reactive polymer compound remains suitable for its intended use after being mixed with the reaction initiator is the "pot life". The gel point (or gelation time) refers to a state in which a liquid begins to exhibit pseudoelasticity. After the polyurethane has gelled (also referred to as 'reacted'), the raw material solidifies enough to be removed from the mold or centrifuge while still maintaining its shape.

For the formation of solid polymer polishing pads, this treatment has the additional concern of preventing the formation of pores in the solid layer. This is especially difficult when the uptime is short. This means that, often, the use of conventional closed molding systems for making such solid polymer polishing pads encounters many limitations, and in some cases, closed molding systems cannot be used. For example, the raw material thickness typically needs to be much larger than an acceptable polishing pad to ensure that the mixture fills the mold. This increases the waste, thereby increasing the economic burden on the pad manufacturing process. The yield of mold processing can be affected by the dense manufacturing window, and the loss of yield also increases the economic burden on the pad manufacturing process. It can be understood that inconsistencies appear in the raw material due to the tight manufacturing window.

According to the present technology, a solid polymer polishing pad is manufactured using centrifugal molding. This treatment involves injecting a liquid polymer mixture into a large rotating drum. The centrifugal force drives the polymer mixture towards the inner surface of the drum, and when the polymer mixture reacts and solidifies, a rectangular belt of solid polymer is obtained. When the polymer mixture is poured into the rotating drum of the centrifugal caster, the polymer mixture spreads and adheres to the walls of the drum. When the polymer mixture reacts and solidifies, there are substantially no voids in most of the cross-sections of the polymer mixture. Any voids present are isolated to the surface of the sheet that faces or is furthest from the inner wall of the drum and is thus easily removed during formation, preparation and/or conditioning.

Centrifugal molding to produce solid polymer sheets enables the production of void-free polishing pads. In addition, the centrifugal molding process can be adjusted to ensure that the Total Thickness Variation (TTV) of the polymer mixture is very small. The temperature and speed (Rotation Per Minute; RPM) of the centrifugal caster used to make the polishing pad can be varied depending on the desired pad properties and the polymer mixture used.

The centrifugal molding systems and methods provided herein allow the formation of thin sheets of solid polymers with low TTV. A thin sheet of polymer (eg, polyurethane) can be easily converted into a solid polymer polishing pad with no voids or voids.

The centrifugal forming method provided herein uses phase separation in a centrifugal forming system to ensure the formation of a multilayer polishing pad having a solid layer and a porous layer with densely packed microspheres. Phase separation can occur when the mixture contains fillers, abrasives, and/or fibers. The microspheres are typically plastic, differ in size, may or may not be expandable, have an enclosed gas or foaming agent, and/or are solid or hollow.

The present technology can form multi-layer polishing pads using different polymer formulations by adding an adhesive between the layers. In addition, the present technique can be used to give rise to a predetermined or desired anisotropic chain structure in a polymer sheet.

The porous layer of the polishing pad (or sub-pad) is advantageous for polishing because of the compressibility of the material resulting from the densely packed pores. Additionally, the closed cell pore structure prevents wicking of fluid into the sub-pad, which can affect polishing performance.

The inner surface of the caster may be smooth or, optionally, a texture may be employed to add grooves or flow paths to the working surface of the polishing pad and/or to enhance the performance of the adhesive used in the construction of the polishing pad. The grooves may be added to the polishing pad during or after the molding process and may be formed on the surface opposite the caster wall. The grooves are useful during use of the polishing pad, ie, during CMP operations, because they enhance the flow of the slurry. In an exemplary embodiment, a pad having a plurality of layers is formed, and then some or all of these layers are exposed in the groove region through a grooving process. For example, the groove reveals a different structure at the groove side and at the bottom of the groove, which is distinct from the top layer. In some cases, the newly exposed layer at the bottom of the groove is stiffer, softer, and/or has pores to facilitate slurry flow. Different groove cross-section shapes, different layer materials exposed in the grooves, and/or other groove geometries (eg, spiral or xy patterns) can be used to influence the flow of the slurry and/or change the grinding efficiency of the polishing pad. is used for

Heating during centrifugal forming is effected by heating the drum and/or the air in the drum by heating components surrounding or adjacent to the forming drum. Typically, the drum is preheated prior to injection of the polymer mixture. Additional treatments may be performed during the forming operation to improve product performance.

The presence of microstructure in the pad material enhances the polishing performance of the polishing pad. This microstructure must be consistent within the pad material to avoid inconsistent polishing performance. The solid pad relies on the microstructure introduced during shaping or conditioning. If a void or voids are present in the pad material, this results in an increased level of polishing rate. This increased level of polishing rate is not sustainable in some cases because voids are not consistently present in the layer. For this reason, it is important that the solid polishing pad contain little or no voids. Efforts to fabricate void-free solid polymer pads have largely been ineffective. On the other hand, the use of centrifugal casters overcomes the problems associated with polymer mixtures while ensuring void-free polymer sheets even when using polymer mixtures with short pot life. Centrifugal casters reduce or eliminate voids or voids in the polymer sheet as centrifugal force moves the polymer mixture to the inner wall of the centrifugal caster, while the voids or cavities are lighter than the polymer mixture and thus move to the opposite surface.

During molding, foam and/or voids migrate to the surface during curing of the polymer and may remain on the surface after curing. These foams and/or voids can be removed by thinning the inner surface of the belt used as the working surface of the polishing pad. Such thinning typically requires removal of 1/1000 to 4/1000 inches, or optionally up to 15/1000 inches.

Centrifugal molding of solid polymer sheets offers unexpected advantages in producing exceptionally flat polymer sheets. Extreme flatness reduces the need for thinning, and consequently prevents loss of raw materials, time and cost due to thinning. Additionally, the present technology reduces or eliminates voids in the polymer molded body as the polymer mixture moves to the drum surface due to centrifugal force, but the voids do not move and are consequently pushed out of the polymer mixture. The substantial absence of voids provides a consistent polishing pad from initial use to final use (also referred to herein as a 'CMP pad', although optional polishing applications are included herein). Polishing pads typically have a thickness of 80/1000 inches or less, and as the polishing pad is used, the polishing pad becomes thinner due to conditioning treatment and wear during use.

The polymer polishing pad formed by centrifugal molding is substantially free of voids or voids and has a substantially uniform thickness. In addition, using mixtures with short pot lives, polymer sheets are formed that are substantially or completely free of voids. Consequently, high manufacturing yields can be achieved using the present technology.

Conventional CMP pad fabrication involves the formation of a cut solid polymer cake or ingot, which requires substantial uniformity from top to bottom and is difficult. In contrast, in the case of the exemplary method according to the present technology using centrifugal molding, the produced solid polymer is hyper-planarized and is only a minimum amount thicker than the target thickness of the CMP pad. By cutting or punching using suitable methods, very large belts are made that can be used to make many top pads (or sub pads), which will increase yield as well as provide a very consistent product that is substantially free of porosity. can

Exemplary methods disclosed herein are used to form two or more separate and distinct layers by molding and gelling a mixture of two or more different polymers. This embodiment is not possible in a closed forming system.

Reinforced pads can be formed using the present technology by placing a fiber mesh on top of a partially reacted initial polymer sheet and then forming an additional layer on the fiber mesh. Optimization of the centrifugal caster setting using the polymer mixture formulation allows the formation of anisotropic polymer sheets. When using a solid polymer polishing pad, this offers the advantage of a more consistent chain structure orientation. This allows for more consistent microstructure formation with the pad conditioner. The transfer properties of the polymer sheet can be achieved using this more regular structure.

An exemplary variant of the present technology improves the adhesion between the adhesive (pressure sensitive adhesive or hot melt adhesive) and the polymer pad by slightly roughening the inner surface of the drum. Poor adhesion can cause pad peeling during polishing. This will cause damage to the grinder, scratches on the substrate being polished, and significant downtime of the grinder which will affect efficiency.

1 is a schematic diagram illustrating a rotational molding system 100 including a centrifugal caster 102 and a polymer dispenser 104 . Polymer dispenser 104 contains polymer mixture 106 . The polymer dispenser 104 includes a mixing device, a jacket with or without a heating element having a conduit through which the heated fluid flows, and/or an electrical heating element. The polymer mixture 106 is a polymer mixture that is phase-separated into a plurality of layers only under centrifugal force, and has no phase separation in the absence of ambient pressure. Polymer mixture 106 may be a single polyurethane mixture with microspheres added to change the density of the polymer mixture. Optionally, the polymer mixture 106 includes two or more polymers, and a polymer composite produced in the centrifugal caster 102 by adding foam to the polymer mixture. The term 'foam' associated with a polishing pad refers to a polyurethane (PolyUrethane; also referred to as 'PU') pad having a closed-cell or open-cell structure. Cells can be microspheres surrounded by polyurethane, cavities surrounded by polyurethane, or open cavities passing through polyurethane. The porous pad material is referred to as a 'foam pad'. There are two methods for making foamed products without adding microspheres, 1) adding a blowing agent to the polyurethane mixture, and 2) injecting a gas (eg N ₂ or CO ₂ ) into the mixture. there is.

The polymer mixture 106 is transferred from the polymer dispenser 104 to the drum of the centrifugal caster 102 while the drum 110 rotates along the rotational direction 114 about the axis 112 . It flows into an injection path 108 leading into 110 . The polymer mixture 106 spreads to form a polymer sheet 116 on the inner surface of the drum 110 due to centrifugal force. In the case of the drum 110, the polymer sheet 116 has a cylindrical shape. The drum 110 rotates, and no matter what rotation speed the drum 110 rotates, the centrifugal force experienced by the polymer mixture 106 injected into the drum 110 creates a uniform thickness of the polymer sheet 116 and additionally It has a diameter sufficient to cause separation. Phase separation occurs under centrifugal force and causes the polymer mixture 106 to separate into two or more polymer layers, and/or a pure polymer layer and a polymer layer infused with microspheres.

In some embodiments, drum 110 is heated. The drum 110 may have a smooth inner drum surface, and optionally the drum 110 improves the performance of the adhesive used in the polishing pad, provides grooves in the surface of the polishing pad made according to the present method, and , and/or a textured drum surface that facilitates separation and/or formation of the polishing pad from the reaction molded polymer sheet formed by the method.

2 is a schematic cross-sectional view showing the centrifugal caster 102 after the polymer mixture has undergone phase separation and has formed two separate layers. The polymer mixture 106 is subjected to centrifugal force in the drum 110 and then phase separated into two separate layers: a soft polymer layer 200 and a high density polymer layer 202 . During phase separation, the centrifugal force drives the polymer to one side of the polymer sheet 116 , and the microspheres float toward the surface of the polymer sheet 116 because the density is lower than that of the polymer. This phase separation produces a dense layer and a porous layer. The high-density polymer layer 202 is the denser layer and forms the hard pad of the polishing pad. The high-density polymer layer 202 is a solid polyurethane layer. The soft polymer layer 200 is a porous layer filled with densely packed microspheres, and forms a sub-pad of the polishing pad. The high-density polymer layer 202 is an inner layer in contact with the inner surface of the drum 110 .

The polymer sheet 116 may be thinned before or after forming the outline of the polymer pad to form a groove pattern on the surface of the polymer sheet 116 . Similarly, the surface of the polymer sheet 116 is conditioned to form a scratch pattern on the polymer pad.

In one embodiment, after the high-density polymer layer 202 and the soft polymer layer 200 of the polymer sheet 116 are formed, a third layer of the same or different polymer or another material comprises three (or more) Many) layers are molded onto the polymer sheet 116 to make the polymer pad. If necessary, subsequent layers are formed by adding the same or different polymer layers, as described above.

3 is a schematic diagram showing a cross-section of a centrifugal caster 102 , showing an insert 300 , and a polymer sheet 116 having a high density polymer layer 202 and a soft polymer layer 200 . The drum 110 rotates about an axis 112 in a rotational direction 114 . The insert 300 forms a film on the inner wall of the drum 110 . In one embodiment, the insert 300 is permanent (eg, Teflon®), semi-permanent (eg, Teflon®) within the centrifugal caster 102 to facilitate release of the solid polymer after molding. spray), or as a temporary coating, a mold release agent. In particular, in some cases, the inner surface of the drum 110 is sprayed with a Teflon® coating after a certain number of moldings, such as, for example, 20 moldings. Optionally, the insert 300 is a mold release sheet made of High-Density PolyEthylene (HDPE), a thermoplastic material, PolyTetraFluoroEthylene (PTFE), or silicone. In certain instances, the insert 300 is replaced infrequently, for example once every few months.

In another embodiment, the insert 300 formed on the high density polymer layer 202 is grooved to form a groove pattern on the surface of the polymer sheet 116 . In further embodiments, the insert 300 has flow paths for forming different types of polishing pads.

4 is a schematic diagram showing a cross-section of the polymer pad 400 . After the high-density polymer layer 202 and the soft polymer layer 200 are formed, the drum 110 is stopped and the polymer sheet 116 comprising the two layers is removed from the drum 110 . The process of removing the polymer sheet 116 includes a process of cutting the polymer sheet 116 along a line parallel to the axis 112, and accordingly, the polymer sheet 116 is deformed from a cylindrical belt shape to a rectangular shape. do. Optionally, the cutting process may be performed outside the centrifugal caster. The polymer pad 400 is cut out or punched out from the polymer sheet 116 . The removed polymer pad 400 includes a sub pad 402 and a hard pad 404 . The hard pad 404 is formed from the high-density polymer layer 202 while the sub-pad 402 is formed from the soft polymer layer 200 . Both the hard pad 404 and the sub pad 402 can be used for polishing. The perforated side (sub-pad 402; not sub-pad for polishing applications) can be used for polishing, although the solid side (hard pad 404) is typically used for polishing, and is a dense cluster of microspheres. As a result, uniform grinding is provided. Since the sub pad 402 has extremely dense pores, the compression ratio is further increased and wicking is prevented. Before or after forming the polymer pad, the surface of the polymer sheet 116 is thinned so that both layers have a more uniform thickness and/or to eliminate surface imperfections. Additionally, sub-pads may be added to one side of this assembly either before or after the contouring and/or thinning process.

5 is a schematic diagram illustrating a cross-section of a centrifugal caster 102 , showing an insert 500 , and a polymer sheet 116 having a high density polymer layer 202 and a soft polymer layer 200 . The inner insert 500 is a sheet made of HDPE, thermoplastic, PTFE, or silicone, and has a groove pattern similar to that of the insert 300 . The inner insert 500 is placed on the polymer sheet 116 and placed into the drum 110 either by hand or using a mandrel. When using a mandrel, the inner insert 500 surrounds the mandrel so that it can be easily positioned within the drum 110 . In particular, the drum 110 rotates slowly at a low RPM while a mandrel with an inner insert 500 rotating at the same RPM as the drum 110 is inserted into the center of the drum 110 along axis 112 . . The RPM of the drum 110 increases back to its original rotational speed, creating a centrifugal force large enough to pull the inner insert 500 away from the mandrel toward the polymer sheet 116 .

6 is a schematic cross-sectional view illustrating a centrifugal molding system having a mold insert 600 that forms a film on the inner wall of the drum 110 of the centrifugal caster 102 . The mold insert 600 is a sheet made of Teflon®, HDPE, thermoplastic, PTFE or silicone that forms a film on the inner wall of the drum 110 . The mold insert 600 has at least one mold of a polishing pad, and the number of molds depends on the size of the drum 110 and the size of the polishing pad. The mold of mold insert 600 may be a single mold, or it may be a plurality of molds that are fixed or removable and whose distance from axis 112 is variable or fixed to vary the amount of centrifugal force the polymer will experience during the molding process. . The mold or molds of mold insert 600 define the CMP pad and have a textured surface as described above with respect to drum 110 , insert 300 , and/or internal insert 500 . In some embodiments, mold insert 600 has four molds on a sheet that form a film on drum 110 , thus producing four polishing pads in one mold. For this embodiment, the polymer mixture 106 is poured into each mold individually, eliminating the need to cut or punch the polishing pad from the polymer sheet. Through the method of this embodiment, waste can be reduced.

7 is a schematic diagram showing a cross-section of the drum 110 and showing the mold insert 600 and the window 700 . Window 700 is a transparent material (eg, urethane) that enables implementation of optical endpoint technology. Window 700 is placed in the molds of mold insert 600 before the polymer mixture is sent into individual molds. A polymer mixture surrounds the sides of the window 700 . Window 700 may be included within the polishing pad as a window when the polishing pad is removed from the mold, or may be separated from the polishing pad to leave room for a window to be inserted into the polishing pad.

8 is a schematic diagram illustrating a multi-axis rotational molding system 800 including a molding die 802 . The forming mold 802 includes two mold parts: an upper mold part 804 and a lower mold part 806 . The terms 'top' and 'bottom' are used herein for reference only and are not intended to limit the exemplary embodiment. Accordingly, the upper mold portion 804 may be located in the lower region, and the lower mold portion 806 may be located in the upper region. Polymer mixture 808 is provided in one or both of upper mold portion 804 and lower mold portion 806 while upper mold portion 804 and lower mold portion 806 are separated, and then: The upper mold part 804 and the lower mold part are joined as shown in FIG. 8 . The interior space 810 of the molding mold 802 contains the space or is optionally completely filled with the polymer mixture 808 . The upper mold portion 804 and the lower mold portion 806 are sealed together prior to molding to form the forming mold 802 . The molding mold 802 rotates about an axis 812 in a direction 814 , and rotates about an axis 816 in a direction 818 . The axis 812 is shown as bisecting the forming mold 802 , but may optionally be offset from the forming mold 802 . Similarly, the shaft 816 is shown as being off from the forming mold 802 , however, it is possible to optionally bisect the forming mold 802 . One or both of these rotations are initially performed at a slow speed to promote coverage of the inner surface of the forming mold 802 . In a further and optional embodiment, vibration in one or more directions is additionally or optionally used to promote wetting of the mold surface. One or both of the rotations are performed at high rotational speeds to promote movement of the microspheres towards the inner surface and/or to promote flattening of the inner surface of the forming mold 802 . The forming mold forms a cylindrical shape or other suitable shape. The forming mold 802 can be heated, has a smooth inner drum surface, or, optionally, improves the performance of the adhesive used in the polishing pad, provides grooves in the surface of the polishing pad made according to the present method, and , and/or a textured drum surface that facilitates separation and/or formation of the polishing pad from the reactive molded polymer sheet formed by the method.

9 is a process flow diagram illustrating a method 900 according to the present technology using polyurethane. However, the method can also be applied to other polymers, as described herein. As shown in FIG. 9 , the method 900 begins at step 902 in which microspheres are mixed into a polyurethane mixture to form a hybrid mixture. Proceeding from step 902 to step 904, the hybrid mixture is injected into the interior space of the cylinder. Proceeding from step 904 to step 906, the cylinder containing the hybrid mixture in the interior space is rotated about a central axis until the mixture phase separates into two separate layers. Proceeding from step 906 to step 908, the cylinder is heated to a temperature of 140 to 212 degrees Fahrenheit for at least a portion of the time during which the rotating step occurs. Proceeding from step 908 to step 910, a polishing pad is formed from the polyurethane sheet formed after the hybrid mixture is separated into two layers and reacted. The processing sequence ends after step 910 .

Polymer (eg, PolyUrethane (PU)) molding systems involve the process of mixing two or more polymers together to form a polymer composite. To form the polymer composite, foam is added in between, using a centrifugal caster to separate the other polymer mixture formed.

10 is a process flow diagram illustrating an alternative method 1000 of forming a multilayer polishing pad in accordance with the present techniques using polyurethane. However, the method can also be applied to other polymers, as described herein. As shown in FIG. 10 , the method 1000 begins at step 1002 by injecting a composite mixture into the interior space of a cylinder. Proceeding from step 1002 to step 1004, the cylinder confining the composite mixture in the interior space is rotated about a central axis. Proceeding from step 1004 to step 1006, heating the cylinder to a temperature between 104 and 212 degrees Fahrenheit for at least a portion of the time during which the rotating step occurs. Proceeding from step 1006 to step 1008, after the composite mixture is in a gel state, the rigid polyurethane mixture is injected into the inner space of the cylinder. Proceeding from step 1008 to step 1010, the cylinder is rotated and heated until the rigid polyurethane and composite mixture react and form a two-layer polyurethane sheet. Using a composite mixture that has solidified into a gel (also referred to as 'reacted') prior to injection of the rigid polyurethane, the rigid polyurethane layer is formed using a Pressure Sensitive Adhesive (PSA) to bond the two layers together. It will be chemically bonded to the flexible polyurethane layer without the need for Proceeding from step 1010 to step 1012, a polishing pad is formed from a polyurethane sheet comprising two layers. The processing sequence ends after step 1012 .

In another embodiment, the rigid polyurethane mixture is injected into the cylinder to gel before the composite mixture is injected into the cylinder.

In a further embodiment, the thin layer is installed or formed on the surface of the flexible polyurethane layer prior to pouring the composite mixture into the cylinder. The thin layer is made of polyester, fabric, or a conductive material. Optionally, a thin layer of polyester, nylon, fabric, or conductive material may or may not be woven, flanked by or surrounding the polyurethane sheet. In a further embodiment, the conductive material also covers (eg, liquid, sprayed, or aerosolized) the polyurethane sheet prior to forming the polishing pad. In this alternative method, the multilayer polymer pad is formed from a single or a plurality of moldings.

The above description is illustrative and not restrictive. Variations of the present disclosure will become apparent to those skilled in the art upon review of the present disclosure. Accordingly, the scope of the present invention should not be determined with reference to the above detailed description, but should be determined with reference to the full scope of the appended claims and their equivalents.

Claims (28)

A method for manufacturing a multilayer chemical mechanical planarization pad using a centrifugal molding method, the method comprising:
the method
A first polymer mixture comprising at least a polymer compound and a plurality of microspheres is multi-axially and multi-axially rotated about a central axis and a second axis by rotating at least one contoured cylindrical mold insert of a chemical mechanical planarization pad comprising a window in the drum. directional (multi-directional) rotational centrifugal molding;
Under the influence of centrifugal force by the multiaxial and multi-directional rotational centrifugal molding step, the first polymer mixture contains only the polymer compound, does not contain microspheres, does not contain voids or voids, and has a substantially uniform thickness. separating into a porous first layer and a second layer comprising the plurality of microspheres;
forming a multilayer polymer sheet through gelling of the first polymer mixture;
injecting a second polymer mixture into the cylindrical mold insert in the drum before the first polymer mixture is in a gel state and the first polymer mixture is cured;
further multiaxial and multidirectional rotational centrifugal molding of the second polymer mixture by rotating the cylindrical mold insert in the drum about the central axis;
removing the multilayer polymer sheet from the cylindrical mold insert; and
forming a plurality of multilayer chemical mechanical planarization pads from the polymer sheet;
including,
The multi-axis and multi-directional rotational centrifugal forming step comprises rotating the cylindrical mold insert in the drum in a first direction about the central axis and in a second direction about the second axis, wherein the rotating the cylindrical mold insert about the first direction rotates at a higher rotational speed than rotating the cylindrical mold insert within the drum in a second direction about the second axis;
wherein said window enables optical endpoint technology. The method of claim 1 , wherein the plurality of microspheres surround a gas. The method of claim 1,
the second polymer mixture comprises at least a high-density material and a low-density material; and
said second polymer mixture is separated into a third layer comprising said high-density material and a fourth layer comprising said low-density material under the influence of centrifugal force during said further step of multiaxial and multidirectional rotational centrifugation,
and the third layer is located between the second layer and the fourth layer. 4. The method of claim 3, wherein the low density material comprises microspheres surrounding a gas. The method of claim 1,
prior to injecting the second polymer mixture into the cylindrical mold insert, further comprising placing a solid insert on the surface of the second layer;
wherein the solid insert is at least one of polyester, fabric, and a conductive material. The method of claim 1,
Prior to injecting the second polymer mixture into the cylindrical mold insert, further comprising the step of spraying a liquid on the surface of the second layer,
wherein the liquid is at least one of an adhesive and a conductive layer. The method of claim 1,
wherein the cylindrical mold insert and the drum form a rotatable centrifugal caster, the centrifugal caster having a cylindrical interior space, and a dispenser injecting the first polymer mixture into the mold insert of the centrifugal caster. The method of claim 1, wherein the method comprises:
and heating said cylindrical mold to a temperature of 140 to 212 degrees Fahrenheit during said rotating step. The method of claim 1,
The method of claim 1, further comprising treating the surface of the cylindrical mold insert with a mold release agent prior to injecting the polymer mixture into the cylindrical mold insert. The method of claim 1,
forming tissue on at least one of the surface of the cylindrical mold insert and a top liner positioned on the surface of the first polymer mixture;
the organization
Method according to claim 1, characterized in that the perforations formed in the outer rim of the multi-layer chemical mechanical planarization pad are formed. The method of claim 1,
and placing another window on the surface of the cylindrical mold insert prior to injecting the polymer mixture into the cylindrical mold. The method of claim 1,
wherein said plurality of microspheres comprising said second layer are compressible. A system for manufacturing a multilayer chemical mechanical planarization pad using centrifugal molding, the system comprising:
a plurality of polymer mixtures comprising at least a high-density and low-density material, wherein the polymer mixtures do not phase separate under ambient conditions;
Multi-axis and multi-directional rotary centrifugal casters configured for multi-axis and multi-directional rotary centrifugal forming methods
including,
The multi-axis and the multi-directional rotational centrifugal molding method includes rotating a cylindrical mold insert in a drum in first and second directions about a central axis and a second axis, respectively, wherein the cylindrical mold insert in the drum is rotated about the central axis and the second axis. rotating the cylindrical mold insert in the drum in the first direction about an axis rotates at a higher rotational speed than rotating the cylindrical mold insert in the drum in the second direction about the second axis;
wherein the multi-axis and multi-directional rotating centrifugal caster comprises:
drum having an inner wall; and
a mold insert having at least one contour of a chemical mechanical planarization pad comprising a window lining the inner wall of the drum, wherein the window enables optical endpoint technology;
a dispenser outside the mold insert for injecting the plurality of polymer mixtures into the mold insert;
An injection path for guiding the plurality of polymer mixtures injected by the dispenser outside the mold insert into the mold insert
including,
The mold holds the polymer mixture and forms different types of chemical mechanical planarization pads and slurry to ensure that the entire area of the multilayer chemical mechanical planarization pad is covered with the slurry when the mold insert is rotating. A system comprising a channel for improving flow. 14. The method of claim 13,
the central axis is the central axis of the cylinder formed by the centrifugal caster;
wherein the dispenser injects the plurality of polymer mixtures into the interior space of the centrifugal caster. 15. The method of claim 14,
a mandrel insertable along the central axis, and a top liner for imparting tissue to the surface of the polymer mixture;
wherein the mandrel is for positioning a solid insert on a surface of an uppermost layer of the plurality of polymer mixtures in the interior space, the solid insert comprising at least one of a polyester, a fabric, and a conductive material;
wherein the mold insert is slowed down to a lower rotational speed and the mandrel rotates at the same rotational speed,
wherein said rotational speed of said mandrel is subsequently increased to create a centrifugal force pulling said solid insert from said mandrel. 14. The method of claim 13,
The system of claim 1, further comprising a sprayer for spraying a liquid inside the mold insert, wherein the liquid is at least one of a mold release agent, an adhesive, and a conductive layer. 14. The method of claim 13,
and a heater for heating the mold while rotating and gelling the polymer mixture. 14. The method of claim 13,
wherein the mold insert comprises tissue on a surface of the mold insert;
The organization is:
a perforation formed in the outer rim of the multi-layer chemical mechanical planarization pad; and
and forming at least one of a roughening texture on the back side of the pad surface for enhancing adhesion between the pad surface opposite the working surface and the at least one of an adhesive and a sub pad. 14. The method of claim 13,
wherein the mold insert accommodates another window detachable on a surface of the mold insert prior to injecting the plurality of polymer mixtures into the mold insert;
wherein said removable window is integrated into a multilayer chemical mechanical planarization pad formed from said polymer mixture that has been gelled. A method for manufacturing a multilayer chemical mechanical planarization pad using multiaxial and multidirectional rotational centrifugation, comprising:
injecting a polymer mixture comprising at least a polymer compound and a plurality of microspheres into a mold insert having at least one contour of a chemical mechanical planarization pad comprising a window;
sealing the mold insert such that the mold insert confines the polymer mixture;
multiaxial and multidirectional rotational centrifugal molding of the polymer mixture by rotating the mold insert around a plurality of axes dividing the mold insert; Under the influence of centrifugal force by the multi-axial and multi-directional rotational centrifugal molding step, the polymer mixture is prepared as a solid, non-porous product having only the polymer compound, no microspheres, no voids or voids, and a substantially uniform thickness. separating into a first layer and a second layer comprising the plurality of microspheres;
forming a multilayer polymer sheet through gelation of the polymer mixture;
removing the multilayer polymer sheet from the mold insert; and
forming a plurality of multilayer chemical mechanical planarization pads from the polymer sheet;
including,
The multi-axis and multi-directional rotational centrifugal molding includes rotating the mold having the window in first and second directions about a central axis and a second axis, and rotating the mold insert about the central axis. rotating the mold insert in a first direction with a higher rotational speed than rotating the mold insert in a second direction about the second axis,
wherein said window enables scientific endpoint description. 21. The method of claim 20, wherein the plurality of microspheres surround a gas. 21. The method of claim 20, wherein the central axis is perpendicular to the second axis. 21. The method of claim 20, wherein the plurality of axes divide the mold. 21. The method of claim 20, wherein the mold is vibrated to coat the interior space of the mold with the polymer mixture.
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