Chemical mechanical polishing subpad having a porogen with a polymer shell - Patent Application 20070122997

Abstract

A subpad for a chemical mechanical polishing pad, the subpad having a porogen with a polymer shell. A method of making the subpad and a method of making a polishing pad with a polishing surface layer bonded to the subpad layer are also described.

Description

[Technical Field]

[0001] The present disclosure relates generally to polishing pads used in chemical mechanical planarization, and more particularly to subpads having porogens with a polymer shell. [Background technology]

[0002] Integrated circuits are typically formed on substrates by sequentially depositing conductive, semiconductive, and / or insulating layers on a silicon wafer. Various manufacturing processes require planarization of at least one of these layers on a substrate. For example, in certain applications (e.g., polishing a metal layer to form vias, plugs, and interconnects in trenches in a patterned layer), an overlying layer is planarized until the top surface of the patterned layer is exposed. In other applications (e.g., planarizing a dielectric layer for photolithography), an overlying layer is polished until a desired thickness remains above the underlying layer. Chemical mechanical planarization (CMP) is one method of planarization. This planarization method typically involves placing a substrate on a carrier head. The exposed surface of the substrate is typically placed in contact with a polishing pad that rests on a rotating platen. The carrier head provides a controllable load (e.g., applied force) on the substrate to press the substrate against the rotating polishing pad. A polishing liquid, such as a slurry containing abrasive particles, may also be placed on the surface of the polishing pad during polishing.

[0003] A polishing pad may include a top pad, which contacts the surface being polished during polishing, and a subpad, which supports the top pad. One goal of the CMP process is to achieve high polishing uniformity. However, variations in the mechanical properties of the polishing pad can result in poor polishing uniformity and / or performance variations between different batches of CMP pads. The subpad may have either a non-porous structure or a porous structure. Previous approaches to achieving a porous structure in a CMP subpad have various drawbacks. For example, gas-filled pores formed, for example, by using chemical or physical foaming agents, can have low uniformity, larger-than-preferred pore sizes, and / or pitted or torn pore walls (e.g., resulting in adjacent pores becoming interconnected and forming an uncontrolled porous network). These adverse characteristics can result in a CMP pad with variable and difficult-to-control mechanical properties, which in turn result in variable and difficult-to-control CMP performance characteristics. Summary of the Invention

[0004] To aid in understanding the present disclosure, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a diagram of an example system for chemical mechanical planarization (CMP). [Figure 2] FIG. 2 is a diagram of an example CMP pad including a top pad and a subpad with a porogen having a polymer shell. [Figure 3] FIG. 3 is a plot of storage modulus versus temperature demonstrating the thermal stability of example CMP pads fabricated as described in this disclosure. [Figure 4A] FIG. 4A is a plot of removal rates for wafers polished with various CMP pads, including CMP pads fabricated using the methods described in this disclosure. [Figure 4B]FIG. 4B is a plot of removal rates for wafers polished with various CMP pads, including CMP pads fabricated using the methods described in this disclosure. [Figure 5] FIG. 5 is a flow diagram of an example method of making and using a subpad including a porogen with a polymer shell, according to certain embodiments of the present disclosure. [Figure 6] FIG. 6 is a flow diagram of another example method of making and using a subpad including a porogen with a polymer shell, in accordance with certain embodiments of the present disclosure. [Figure 7] FIG. 7 is a flow diagram of yet another example method of making and using a subpad including a porogen with a polymer shell, in accordance with certain embodiments of the present disclosure. [Figure 8] FIG. 8 illustrates the fabrication of the CMP pad of FIG. 2 using skiving (e.g., using the example method of FIG. 7). DETAILED DESCRIPTION OF THE INVENTION

[0006] First, while examples of implementations of embodiments of the present disclosure are provided below, it should be understood that the present disclosure can be implemented using many technologies, whether currently known or unknown. The present disclosure should in no way be limited to the example implementations, drawings, and technologies provided below. Additionally, the drawings are not necessarily drawn to scale.

[0007] The present disclosure recognizes that improved control of the properties of pores formed in the subpad of a CMP pad can result in improved control of mechanical properties and, therefore, overall CMP performance. As described herein, subpads are fabricated with porogens, each of which contains pores (e.g., pores containing a gas and / or liquid pore filler) surrounded by a polymer shell. The pore shell material is different from the surrounding subpad material. During subpad formation, the shell prevents flow between the pores, resulting in a subpad with a highly controlled, closed pore structure (i.e., relatively uniform pore size and little or no interconnections between pores) and therefore reliable mechanical properties. Various novel methods for fabricating these unique subpads and corresponding CMP pads are described in this disclosure (see Figures 5-8 and the corresponding discussion below). For example, subpads can be fabricated by mixing a polymer shell pore filler with a liquid polyurethane prepolymer and initiating a polymerization reaction. Molding-based methods can be used to form subpads having porogens with a polymer shell. Alternatively, the subpad may be formed directly on the top pad (e.g., by casting a mixture containing the subpad precursor components). In the case of casting, the pore filler surrounded by the polymer shell may be in a foamed or unfoamed state. If an unfoamed pore filler is used, a subsequent foaming step may be performed to achieve a further reduction in subpad density, which may be further beneficial to CMP performance.

[0008] Chemical Mechanical Planarization System FIG. 1 illustrates a system 100 for performing chemical mechanical planarization. The system 100 includes a CMP pad 200 (also referred to as a "polishing pad"; see also FIG. 2 and the corresponding discussion below) disposed on or attached to a platen 102. For example, an adhesive layer (not shown) may be used to attach the polishing pad to the platen 102. The platen 102 may typically be rotated during chemical mechanical planarization. A wafer 104 (e.g., a silicon wafer with or without conductive, semiconductive, and / or insulating layers, as discussed above) is attached to a rotating chuck head 106. The wafer 104 may be attached using a vacuum and / or a reversible adhesive (e.g., an adhesive that holds the wafer 104 in place during chemical mechanical planarization but allows the wafer 104 to be removed from the head 106 after chemical mechanical planarization). As shown in FIG. 1, pressure may be applied to the wafer 104 during chemical mechanical planarization (eg, to promote contact between the surface of the wafer 104 and the polishing pad 200).

[0009] An example polishing pad 200 is shown in FIG. 1 and described in more detail below. Briefly, polishing pad 200 generally has a circular or approximately cylindrical shape (i.e., with an upper surface, a lower surface, and curved edges). Polishing pad 200 may include a polyurethane, such as a soft polyurethane or a hard polyurethane. Example compositions and methods used to manufacture example polishing pad 200 are described in more detail below. In some embodiments, the composition includes one or more porogens. As shown in more detail in FIG. 2 and described below, the porogens may include liquid or gas pores surrounded by a polymer shell. Polishing pad 200 may have any suitable thickness and any suitable diameter (e.g., for use with a CMP system such as system 100 described above). For example, the thickness of polishing pad 200 may range from about 0.5 millimeters (mm) or less to more than 5 centimeters (cm). In some embodiments, the thickness of polishing pad 200 may range from 1 mm to 5 mm. The diameter of the polishing pad is generally selected to match or be slightly smaller than the diameter of the platen 102 of the polishing system 100 being used. The polishing pad 200 generally has a uniform or near-uniform thickness (e.g., a thickness that varies by 50% or less, 25% or less, 20% or less, 10% or less, 5% or less, or less over the radial extent of the polishing pad).

[0010] A slurry 108 may be applied to the surface of the polishing pad 200 before and / or during chemical mechanical planarization. The slurry 108 may be any slurry suitable for planarizing the type of wafer and / or layer material to be planarized (e.g., to remove a silicon oxide layer from the surface of the wafer 104). The slurry 108 generally includes a fluid and abrasive particles and / or chemically reactive particles. Any suitable slurry 108 may be used. For example, the slurry 108 may be reactive with one or more materials to be removed from the surface being planarized.

[0011] Conditioner 110 is a device configured to condition the surface of polishing pad 200. Conditioner 110 generally contacts the surface of polishing pad 200 and removes a portion of the top layer of polishing pad 200 to improve its performance during chemical mechanical planarization. For example, conditioner 110 may roughen the surface of polishing pad 200.

[0012] Polishing pad example FIG. 2 shows an example CMP pad 200 in more detail. The CMP pad 200 includes a top pad 202 and a subpad 204. The CMP pad 200 generally has a circular or approximately cylindrical shape. The thickness of the CMP pad 200 can range from about 1 mm to about 10 mm or more. The diameter of the CMP pad 200 can range from about 500 mm to about 800 mm. The CMP pad 200 generally has a uniform thickness. A uniform thickness is defined as a thickness that varies by 50% or less, 25% or less, 20% or less, 10% or less, 5% or less, or less across the radial extent of the pad. That is, the thickness measured near the center of the pad 200 is substantially the same as the thickness near the edges of the pad 200.

[0013] The top pad 202 may be a polyurethane material, such as a thermoset polyurethane, or any other suitable material. As shown in side view in FIG. 2, the top pad 202 may include grooves or any other suitable structure or pattern to facilitate CMP. For example, the grooves may facilitate transporting away etched material and / or any other products of the CMP process from the top pad 202 and the surface of the wafer 104 being planarized. The top pad 202 may have any suitable thickness. For example, the thickness of the top pad 202 may be in the range of about 0.2 mm to about 5 mm.

[0014] The subpad 204 may be a polyurethane material, such as a thermoset polyurethane. The subpad 204 may have any suitable thickness. For example, the thickness of the subpad 204 may be in the range of about 0.2 mm to about 5 mm. The subpad 204 typically includes a porogen 206 distributed throughout the body of the subpad 204. The density of the subpad 204 with the porogen 206 is typically about 450 kg / m 3 ~about 900kg / m 3 The density of Porogen 206 is in the range of about 0.010 kg / m 3 ~about 0.10kg / m 3 The density of the porogen generally corresponds to the mass of porogen (e.g., the mass of gas and / or liquid in the pores 212) per unit volume of the subpad 204 body. In some embodiments, the density of the subpad 204 with porogen 206 is about 450 kg / m 3 ~about 800kg / m 3 The density and amount of porogen 206 can be adjusted to impart desired mechanical properties to the subpad 204 and CMP pad 200.

[0015] As shown in the close-up view 208 of the subpad 204, each of the porogens 206 includes pores 212 surrounded by a polymer shell 210. The pores 212 of each porogen 206 may contain or be filled with a gas or a mixture of a gas and a liquid. For example, the pores 212 may contain or be filled with one or more of n-pentane, iso-pentane, butane, and / or iso-butane. The polymer shell 210 may be any material suitable for stabilizing the porogens 206 during the manufacture of the subpad 204. In some embodiments, the polymer shell 210 includes a block copolymer, polyvinylidene chloride, acrylonitrile, and / or one or more acrylic materials. In some embodiments, the porogens 206 have an average pore size (e.g., diameter) of about 5 micrometers to about 100 micrometers. In some embodiments, the porogens have an average pore size (e.g., diameter) of about 15 micrometers to about 50 micrometers.

[0016] The presence of the polymer shell 210 helps prevent rupture of pores and interconnections between pores in the subpad 204. For example, due at least in part to the presence of the polymer shell 210, greater than 99% of the porogens 206 in the subpad 204 may have a closed-cell structure (i.e., no interconnections with other pores 212, and gas and / or liquid within any pore 212 cannot migrate to another pore 212). The presence of the polymer shell 210 may also help facilitate a narrower porogen 206 size distribution than previously possible, and therefore improved control over the mechanical properties of the subpad 204.

[0017] The benefits of the novel subpad 204 described above provide improved control of the mechanical properties and CMP performance of the CMP pad 200. For example, the subpad 204 may have a compressive force deflection (CFD) of about 25% from 5 psi (about 34.5 kPa) to 200 psi (about 137.9 kPa) (e.g., a 25% volume loss over this pressure range). The hardness of the subpad 204 may be in the range of about 10 Shore A to about 90 Shore A. The damping or tan δ of the subpad 204 may be in the range of about 0.02 to about 0.50. The elastic modulus (E') of the subpad 204 may be in the range of about 0.1 MPa to about 400 MPa.

[0018] The top pad 202 and subpad 204 may be held together with or without an adhesive to form the CMP pad 200. For example, if an adhesive is used, the top pad 202 may be secured to the subpad 204 by a thin adhesive layer (e.g., a layer of pressure-sensitive adhesive). Optionally, other adhesives may be used in addition or instead. For example, the adhesive may be a hot melt adhesive, or the polishing portion and the support portion may be connected by laminating a thin layer of thermoplastic material between the top pad 202 and the subpad 204. A platen adhesive may be used to secure the CMP pad 200 to the platen 102 shown in FIG. 1 for purposes of performing CMP.

[0019] Thermal Stability of Exemplary Polishing Pads FIG. 3 is a plot 300 of storage modulus and tan δ values ​​versus temperature for an example CMP pad. Plot 300 shows that within the temperature range of 25° C. to 100° C., typically experienced during CMP, a CMP pad fabricated with a subpad comprising porogen 206 with a polymer shell 210 (circles in FIG. 3 ) exhibits greater thermal stability than a conventional subpad (squares in FIG. 3 ). The storage modulus of the control sample (left y-axis) is lower and undergoes a relatively large change over this temperature range, while the novel subpad maintains a higher and relatively more stable storage modulus from 25° C. to 100° C. The tan δ of the control sample (right y-axis) decreases by a relatively large amount over this temperature range, from approximately 0.13 to 0.02, while the novel subpad maintains a more stable tan δ value from 25° C. to 100° C.

[0020] Removal rate performance of example polishing pads This example shows a comparison of removal rate performance between two subpads of the present invention having porogens with polymer shells made by the methods described herein and a commercially available subpad.

[0021] Two separate subpads were fabricated using porogens of different sizes, each with a polymer shell. Subpad A was fabricated using a porogen with a 20 micron (20 μm) average size and a polymer shell (foamed Nouryon Expancel, 20 μm diameter). Subpad B was fabricated using a porogen with a 40 micron (40 μm) average size and a polymer shell (foamed Nouryon Expancel, 40 μm diameter).

[0022] Subpads of the present invention were fabricated by mixing a porogen with a polymer shell with a liquid polyurethane prepolymer to achieve a mass-to-volume ratio of 0.77 for Subpad A and 0.65 for Subpad B. Each resulting mixture was transferred onto a vacuum rotating platen into a mold containing a top pad (E6088 Top Pad, CMC Materials Inc.) held in place with the grooved side facing down. Using a spin-casting method, the liquid polyurethane prepolymer mixture containing the porogen was dispensed onto the backside of the top pad while the platen was rotating. Polymerization of the liquid polyurethane prepolymer mixture containing the porogen was initiated by heating the mixture with an infrared heater while the platen was still rotating. After polymerization, the resulting pads, each with a top pad bonded to its respective subpad, were removed from the mold and analyzed for the parameters described below.

[0023] Compressive force deflection (CFD) was measured using known methods. To increase resolution, a dynamic mechanical analysis (DMA) instrument was used to generate stress-strain curves in the compression mode. CFD was measured at 2% strain (compressive deflection). Subpad hardness measurements were performed using a Shore A durometer. [Table 1]

[0024] The parameters in the table above represent two types of subpads that can be made using porogens with polymer shells according to the present invention, both of which were formed on the backside of an E6088 top pad by spin casting during the molding process.

[0025] 4A and 4B show plots 400 and 450 of removal rate profiles (i.e., removal rate as a function of radial position on the polished wafer) achieved by a CMP pad of the present invention having a porogen with a polymer shell (subpad A, described above) and by a commercially available polishing pad (E6088 having a semi-closed cell structure and a foam subpad laminated to an E6088 top pad). Control 1 represents a pad with a hard subpad, while Control 2 represents a pad with a soft subpad. Thus, all four pads were constructed using the same E6088 top pad material but with different subpads attached (two control pads with previously available subpads and two pads with the new subpad with a porogen with a polymer shell, as described in this disclosure). These CMP pads were tested under two different polishing conditions, and the results are shown in FIGS. 4A and 4B.

[0026] Figure 4A shows the removal rate profiles achieved by each CMP pad using a standard "flat" pressure profile, in which a uniform downward force is applied to the wafer during polishing. The control pads (Controls 1 and 2) exhibit an increased removal rate at the edge of the wafer, which can result in overpolishing and / or damage to the wafer's edge during polishing. The CMP pad with novel subpad 1 (Subpad A, described above) achieves a different removal profile with a decreased removal rate near the edge, while the CMP pad with novel subpad 2 performs similarly to the previous subpads (Controls 1 and 2).

[0027] Figure 4B shows the removal rate profiles achieved by each CMP pad using reduced downward pressure at the edge of the wafer being polished. For control pads 1 and 2, this change in pressure distribution near the edge of the wafer causes increased removal rate variation near the edge of the wafer. However, the CMP pad with novel subpad 1 (subpad A described above) has a relatively flat removal rate profile under these test conditions. Therefore, this novel CMP pad with a subpad having a porogen with a polymer shell exhibits improved etch uniformity under these test conditions.

[0028] Methods of manufacturing and using subpads and CMP pads 5 illustrates an example method 500 for manufacturing a subpad 204 and a CMP pad 200 and using the CMP pad 200 according to a preferred embodiment of the present disclosure. In this example, in step 502, a mixture including a porogen 206 with a polymer shell 210 is prepared. For example, the porogen 206 with the polymer shell 210 can be prepared by mixing a prepolymer of the polymer shell 210 with a pore filler (e.g., gas and / or liquid) in a solvent, stirring the mixture, and initiating polymerization of the prepolymer of the polymer shell 210 to form the porogen 206. As another example, the porogen 206 with the polymer shell 210 can be prepared by mixing a polymer of the polymer shell 210 with a pore filler (e.g., gas and / or liquid) in a solvent and stirring the mixture to form the porogen 206. The preparation of the porogen 206 can include adding a surfactant along with a particle stabilizer. Examples of such particle stabilizers include silica and magnesium particles.

[0029] In step 504, the porogen 206 with the polymer shell 210 is mixed with the prepolymer (e.g., liquid polyurethane prepolymer) of the subpad 204. For example, the porogen 206 may be mixed at a density of about 150 kg / m 3 ~about 900kg / m 3 (e.g., or approximately 450 kg / m 3~about 900kg / m 3 ) with the subpad prepolymer in a mass-to-volume ratio suitable to achieve a subpad density within the range of 0.1 to 1.0. In some embodiments, the porogen 206 with the polymer shell 210 is formed in the subpad prepolymer. For example, the components present in the pores 212 (e.g., gas and / or liquid pore filler) and the prepolymer (e.g., or polymer) of the polymer shell 212 may be mixed with the subpad prepolymer. This mixture may be appropriately mixed or agitated to aid in forming the porogen 206 in the prepolymer of the subpad 204. In some cases, the porogen 206 with the polymer shell 210 is mixed with the prepolymer of the subpad 204 (e.g., a liquid polyurethane prepolymer) along with additional additives such as a curing agent and / or a softening agent. The addition of the curing agent and / or other additives may initiate chemical polymerization of the prepolymer of the subpad 204.

[0030] In step 506, the mixture from step 504 may be transferred to a mold. The mold may have the "inverse" shape of the desired shape of the subpad 204. In some embodiments, the mixture from step 504 is not cast into a mold (see, e.g., method 600 of FIG. 6, described below). For example, in some embodiments, the subpad 204 may be formed directly on the top pad 202 (e.g., via a casting method or the like, as described with respect to step 606 of FIG. 6, below).

[0031] In step 508, polymerization of the prepolymer is initiated to produce a subpad 204 comprising a porogen 206 with a polymer shell 210. In some embodiments, the prepolymer is thermally polymerized (e.g., via exposure to an appropriate temperature for an appropriate time). More generally, the polymerization reaction may include exposure to one or more of appropriate temperature / heat conditions, a polymerization agent, and / or light of an appropriate wavelength and / or intensity.

[0032] In step 510, the subpad from step 508 may be bonded to the top pad 202 (e.g., with or without an adhesive) to produce the CMP pad 200. The bonding of the top pad 202 and the subpad 204 in step 510 may be achieved with or without an adhesive. In some cases, an adhesive may be disposed on one or both of the top pad 202 and the subpad 204 to bond them to form the CMP pad 200. In some cases, materials may be adhered to each other without an adhesive. In some cases, a polymer mixture may be disposed on the surface of the subpad 204 (e.g., using an extrusion process or a reaction injection molding process), and after the top pad 202 and the subpad 204 are placed in contact, polymerization of the polymer mixture (e.g., based on exposure to appropriate thermal conditions, a polymerization agent, and / or light of an appropriate wavelength and / or intensity) may be initiated to bond the top pad 202 to the subpad 200.

[0033] In step 512, the CMP pad from step 510 is used for chemical mechanical planarization. For example, CMP pad 200 can be used in system 100 described above with respect to FIG.

[0034] 6 illustrates another example method 600 of manufacturing a subpad 204 and a CMP pad 200 and using the CMP pad 200 according to a preferred embodiment of the present disclosure. In this example, in step 602, a mixture including a porogen 206 with a polymer shell 210 is prepared. For example, the porogen 206 with the polymer shell 210 can be prepared by mixing a prepolymer of the polymer shell 210 with a pore filler (e.g., gas and / or liquid) in a solvent, stirring the mixture, and initiating polymerization of the prepolymer of the polymer shell 210 to form the porogen 206. As another example, the porogen 206 with the polymer shell 210 can be prepared by mixing a polymer of the polymer shell 210 with a pore filler (e.g., gas and / or liquid) in a solvent and stirring the mixture to form the porogen 206. The preparation of the porogen 206 can include adding a surfactant along with a particle stabilizer. Examples of such particle stabilizers include silica and magnesium particles.

[0035] In step 604, the porogen 206 with the polymer shell 210 is mixed with the prepolymer (e.g., liquid polyurethane prepolymer) of the subpad 204. For example, the porogen 206 may be mixed at a density of about 150 kg / m 3 ~about 900kg / m 3 In some embodiments, the density of the subpad is about 450 kg / m 3 ~about 900kg / m 3In some embodiments, the porogen 206 with the polymer shell 210 is formed in a subpad prepolymer. For example, the components present in the pores 212 (e.g., gas and / or liquid pore filler) and the prepolymer (e.g., or polymer) of the polymer shell 212 can be mixed with the subpad prepolymer. This mixture can be appropriately mixed or agitated to aid in forming the porogen 206 in the prepolymer of the subpad 204. In some cases, the porogen 206 with the polymer shell 210 is mixed with the prepolymer of the subpad 204 (e.g., a liquid polyurethane prepolymer) along with additional additives such as a hardener and / or a softener. The addition of the hardener and / or other additives can initiate chemical polymerization of the prepolymer of the subpad 204.

[0036] In step 606, the mixture from step 604 may be transferred to the surface of the top pad 202. In some embodiments, the mixture from step 604 is transferred to the surface of the top pad 202 by spin-coating the mixture onto the top pad 202. The spin-coating speed (e.g., in revolutions per minute) may be adjusted to achieve a desired thickness of the mixture on the surface of the top pad 202, such that the resulting subpad 204 has a desired thickness. In some embodiments, the mixture from step 604 is transferred to the surface of the top pad 202 using an extrusion process. In some embodiments, the mixture from step 604 is transferred to the surface of the top pad 202 using another method, such as drop coating or the like. In some embodiments, the mixture from step 604 is deposited on the surface of the top pad 202 using an additive manufacturing method, such as 3D printing. In some embodiments, the subpad material is dispensed using an additive manufacturing method. The top pad material is then dispensed onto the subpad 204 using an additive manufacturing method.

[0037] In step 608, polymerization of the prepolymer is initiated to produce a subpad 204 comprising a porogen 206 with a polymer shell 210. In some embodiments, the prepolymer is thermally polymerized (e.g., via exposure to an appropriate temperature for an appropriate time). More generally, the polymerization reaction may include exposure to one or more of appropriate temperature / heat conditions, a polymerization agent, and / or light of an appropriate wavelength and / or intensity. The subpad 204 adheres to the top pad 202 after the polymerization process, thereby forming the CMP pad 200.

[0038] In step 610, the CMP pad from step 608, the CMP pad, is used for chemical mechanical planarization. For example, CMP pad 200 can be used in system 100 described above with respect to FIG.

[0039] FIG. 7 illustrates an example method 700 for fabricating a subpad 204 and a CMP pad 200 and using the CMP pad 200, according to a preferred embodiment of the present disclosure. In the example method 700, the CMP pad 200 is fabricated from a multilayer structure using skiving (see FIG. 8 for further illustrative illustration). In this example, in step 702, a mixture including a porogen 206 with a polymer shell 210 is prepared. For example, the porogen 206 with the polymer shell 210 can be prepared by mixing a prepolymer of the polymer shell 210 with a pore filler (e.g., gas and / or liquid) in a solvent, stirring the mixture, and initiating polymerization of the prepolymer of the polymer shell 210 to form the porogen 206. As another example, the porogen 206 with the polymer shell 210 can be prepared by mixing a polymer of the polymer shell 210 with a pore filler (e.g., gas and / or liquid) in a solvent, and stirring the mixture to form the porogen 206. The preparation of porogen 206 may include adding a surfactant along with a particle stabilizer, examples of which include silica and magnesium particles.

[0040] In step 704, the porogen 206 with the polymer shell 210 is mixed with the prepolymer (e.g., liquid polyurethane prepolymer) of the subpad 204. For example, the porogen 206 may be mixed at a density of about 150 kg / m 3 ~about 900kg / m 3 The porogen 206 in the subpad 204 may be mixed with the subpad prepolymer in a mass-to-volume ratio suitable to achieve a subpad density in the range of about 0.010 kg / m 3 ~about 0.10kg / m 3 In some embodiments, the porogen 206 with the polymer shell 210 is formed in the subpad prepolymer. For example, the components present in the pores 212 (e.g., gas and / or liquid pore filler) and the prepolymer (e.g., or polymer) of the polymer shell 212 can be mixed with the subpad prepolymer. This mixture can be appropriately mixed or agitated to aid in forming the porogen 206 in the prepolymer of the subpad 204.

[0041] In step 706, the mixture from step 704 may be transferred to a mold. The mold may have the "inverse" shape of the desired shape of the subpad 204. In some embodiments, the mixture from step 704 is not cast into a mold (see, e.g., method 600 of FIG. 6, described below). For example, in some embodiments, the subpad 204 may be formed directly on the top pad 202 (e.g., via a casting method or the like, as described with respect to step 606 of FIG. 6, below).

[0042] In step 708, polymerization of the prepolymer is initiated to produce a subpad 204 comprising a porogen 206 with a polymer shell 210. In some embodiments, the prepolymer is thermally polymerized (e.g., via exposure to an appropriate temperature for an appropriate time). More generally, the polymerization reaction may include exposure to one or more of appropriate temperature / heat conditions, a polymerization agent, and / or light of an appropriate wavelength and / or intensity.

[0043] In step 710, the top pad 202 is bonded to the upper and lower surfaces of the subpad 204 from step 708 to produce a multi-layer structure. FIG. 8 shows an example 800 of such a multi-layer structure. The multi-layer structure 800 includes a subpad 204, with the top pad 202 attached to both the upper and lower surfaces of the subpad 204. The bonding of the top pad 202 and the subpad 204 in step 710 can be achieved with or without adhesive. In some cases, adhesive can be disposed on one or both of the top pad 202 and the subpad 204 to bond the top pad 202 and the subpad 204 to form the multi-layer structure 800 shown in FIG. 8. In some cases, the materials of the top pad 202 and the subpad 204 can adhere to each other without the use of adhesive. Although example method 700 describes forming subpad 204 in a mold (see steps 706 and 708), it should be understood that a subpad may be formed directly on one of the top pads 202 (e.g., as described above with respect to steps 606 and 608 of FIG. 6 ). In such a case, the other top pad 202 may be adhered to the remaining exposed surface of the joined subpad 204 to form multi-layer structure 800 of FIG. 8 .

[0044] In step 712, skiving is performed to separate (e.g., cut) the multi-layer structure 800 into two CMP pads 200, as shown in FIG. 8 . Skiving involves cutting along the length of the subpad 202 (e.g., approximately near the center of the subpad 204, as shown in FIG. 8 ). Skiving may be performed at or near the center of the subpad 204, at or near the center of the multi-layer structure 800, or at any suitable location along the depth of the subpad 204 (e.g., to form CMP pads 200 with the same or different subpad thicknesses). In step 714, the CMP pad 200 from step 712 is used for chemical mechanical planarization. For example, the CMP pad 200 may be used in the system 100 described above with respect to FIG. 1 .

[0045] Using one of the methods 500, 600, or 700 described above, a CMP pad 200 can be manufactured with a subpad 204 having a more uniform and controlled pore structure than is possible using previous techniques. The methods described in this disclosure (e.g., with respect to FIGS. 5, 6, and 7) also facilitate the production of CMP pads with controlled mechanical properties and variable thicknesses at low cost. The controlled, smaller pore size of the subpad 204 described in this disclosure generally provides improved etching performance (see FIG. 4B). It should be understood that the steps of one or more example methods described with respect to FIGS. 5, 6, and 7 may be combined to produce a CMP pad 200 having at least some of the features and advantages described in this disclosure.

[0046] Modifications, additions, or omissions may be made to the systems, devices, and methods described herein. System and device components may be integrated or separated. Furthermore, system and device operations may be performed by more, fewer, or other components. Methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. Additionally, system and device operations may be performed using any suitable logic. As used in this document, "each" means each member of a set, or each member of a subset of a set.

[0047] As used herein, "or" is inclusive and not exclusive, unless clearly indicated otherwise or indicated otherwise by context. Thus, as used herein, "A or B" means "A, B, or both," unless clearly indicated otherwise or indicated otherwise by context. Furthermore, "and" means both together and severally, unless clearly indicated otherwise or indicated otherwise by context. Thus, as used herein, "A and B" means "A and B, together or severally," unless clearly indicated otherwise or indicated otherwise by context.

[0048] The scope of the present disclosure encompasses all changes, substitutions, variations, changes, and alterations to the example embodiments described or illustrated herein that would be understood by a person skilled in the art. The scope of the present disclosure is not limited to the example embodiments described or illustrated herein. Furthermore, although the present disclosure describes and describes corresponding embodiments herein as including particular components, elements, features, functions, operations, or steps, any of these embodiments may include any combination or permutation of any components, elements, features, functions, operations, or steps described or illustrated anywhere herein that would be understood by a person skilled in the art. Furthermore, references in the appended claims to a device or system, or a component of a device or system, being configured to perform, arranged to perform, capable of performing, formed to perform, enabled to perform, operable to perform, or acting to perform a particular function encompass the device, system, or component to the extent that the device, system, or component is so configured, arranged, capable, formed, enabled, operable, or acting, regardless of whether it or that particular function is activated, operated, or unlocked. Additionally, although this disclosure describes or illustrates particular embodiments as providing certain advantages, the particular embodiment may provide none of these advantages, some of these advantages, or all of these advantages.

[0049] The use of the terms "a," "an," "the," and similar referents in the context of describing the present invention (particularly in the context of the claims below) should be construed to include both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" should be construed as open-ended terms (i.e., meaning "including, but not limited to"), unless otherwise indicated. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, and each separate value is incorporated herein by reference as if it were individually recited herein. The use of any examples or exemplary language (e.g., "such as") provided herein is merely intended to better illustrate the disclosure and does not impose limitations on the scope of the claims.

Claims

1. 1. A subpad for a chemical mechanical polishing pad, comprising: a thermoset polyurethane body; and a porogen having a polymeric shell and distributed within said polyurethane body; Equipped with The subpad has a compressibility at 25% strain (CFD) of 34 kPa to 1380 kPa (5 psi to 200 psi), a hardness of about 10 Shore A to about 90 Shore A, a tan delta of about 0.02 to about 0.5, a modulus of elasticity (E') of about 0.1 MPa to about 400 MPa, and / or a thickness of about 0.2 mm to about 5 mm.

2. The subpad of claim 1 , wherein the porogen has an average pore size of from about 5 micrometers to about 100 micrometers.

3. The subpad of claim 2 , wherein the porogen has an average pore size of from about 15 micrometers to about 50 micrometers.

4. The density of the subpad is about 150 kg / m 3 The subpad of claim 1, wherein the subpad has a modulus of from about 900 kg / m 3 to about 900 kg / m 3 .

5. The density of the subpad is about 450 kg / m 3 ~Approx. 800kg / m 3 5. The subpad of claim 4, wherein:

6. 10. The subpad of claim 1, wherein the polymeric shell comprises a material selected from the group consisting of block copolymers, polyvinylidene chloride, acrylonitrile, and acrylic materials.

7. The subpad of claim 1 , wherein the porogen is filled with a gas or a mixture of a gas and a liquid.

8. 8. The subpad of claim 7, wherein the porogen is filled with one or more materials selected from the group consisting of n-pentane, iso-pentane, butane, and iso-butane.

9. 10. The subpad of claim 1, wherein greater than 99% of the porogen are closed cells.

10. A chemical mechanical polishing pad comprising a top pad layer and a subpad layer comprising the subpad of claim 1.

11. 11. The chemical mechanical polishing pad of claim 10, wherein the top pad layer and the subpad layer are held together without an adhesive.

12. The chemical mechanical polishing pad of claim 10 , wherein the top pad layer and the subpad are held together with an adhesive.

13. 1. A method for manufacturing a chemical mechanical polishing pad, comprising: forming a subpad having a thermosetting polyurethane body and a porogen having a polymeric shell distributed in the polyurethane body on a top pad by one or more of the following processes: (a) spin-coating a mixture comprising the porogen having the polymer shell and a liquid polyurethane prepolymer onto a surface of the top pad material and initiating polymerization of the mixture to form the chemical mechanical polishing pad; (b) transferring a mixture comprising the porogen having the polymer shell and a liquid polyurethane prepolymer onto a surface of the top pad and initiating polymerization of the mixture to form the subpad bonded to the top pad, thereby forming the chemical mechanical polishing pad; (c) forming the subpad with the porogen having the polymer shell, forming the top pad on both the top and bottom surfaces of the subpad, and severing the subpad to form two chemical mechanical polishing pads; (d) transferring a mixture comprising the porogen with the polymer shell and a liquid polyurethane prepolymer onto a surface of the top pad using an extrusion process and initiating polymerization of the mixture to form the subpad bonded to the top pad, thereby forming the chemical mechanical polishing pad; (e) forming the subpad with the porogen having the polymer shell, transferring a polymer mixture onto a surface of the subpad using an extrusion process, and initiating polymerization of the polymer mixture to bond the top pad to the subpad, forming the chemical mechanical polishing pad; and (f) forming the subpad with the porogen having the polymer shell, and transferring a polymer mixture onto the surface of the subpad using a reaction injection molding process and initiating polymerization of the polymer mixture to bond the top pad to the subpad, thereby forming the chemical mechanical polishing pad; The method of claim 1, wherein the bonding is performed using a bonding agent.

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