Polishing pads and systems for and methods of using same

Abstract

A polishing pad includes a textured polishing layer comprising a working surface and a second surface opposite to the working surface. The textured polishing layer includes a polymeric blend comprising between 40 and 95 wt.% of a thermoplastic urethane and between 5 and 60 wt.% of a styrene copolymer, based on the total weight of the textured polishing layer.

Description

Technical Field

[0001] This disclosure relates to polishing pads that can be used for polishing substrates, and systems and methods for using such polishing pads. Simple Explanation of the Diagram

[0002] 10: Textured Polishing Layer / Polishing Layer / Textured Layer 10': Textured Polishing Layer 12: Working surface 13: Second Surface 14: Platform Area 16: Precision forming hole 16a: Sidewall 18: Precision forming protrusions 18a: Sidewall 18b: Remote 19: Mega Channel 22: Secondary surface layer 23: Main body layer 30: Sub-pad 40: Foamed body layer 50: Polishing Pad 100: Polishing System / System 110: Substrate 130: Carrier Assembly 140:Table 145: Drivetrain 150: Polishing Pad 160: Polishing solution 170: Adhesive layer A: Arrow B: Arrow C: Arrow

[0003] With reference to the accompanying drawings, and by considering the implementation methods of the various embodiments of this disclosure as described below, a more complete understanding of this disclosure can be achieved, wherein: [Figure 1A] is a schematic cross-sectional view of a portion of a textured polished layer according to some embodiments of the present disclosure. [Figure 1B] is a schematic cross-sectional view of a portion of a textured polished layer according to some embodiments of the present disclosure. [Figure 1C] is a schematic cross-sectional view of a portion of a textured polished layer according to some embodiments of the present disclosure. [Figure 2] is a schematic cross-sectional view of a polishing pad according to some embodiments of the present disclosure. [Figure 3] is a schematic diagram illustrating an example of a polishing system utilizing a polishing pad and method according to some embodiments of the present disclosure. Implementation

[0004] Various articles, systems, and methods have been used for substrate polishing. Polishing articles, systems, and methods are selected based on the desired end-use characteristics of the substrate, such as surface finish (e.g., surface roughness and defects (e.g., scratches, dents, and the like)) and planarity, including both local planarity (i.e., planarity in a specific area of ​​the substrate) and overall planarity (i.e., planarity across the entire substrate surface). Because micron- or even nanometer-scale features need to be polished to required specifications, the requirements for the end-use can be extremely stringent, making the polishing of substrates such as semiconductor wafers particularly challenging. Polishing procedures, along with improving or maintaining the desired surface finish, typically also require material removal, which may include material removal from a single substrate material or simultaneous material removal from a combination of two or more different materials in the same plane or within the same substrate layer. Materials that can be polished individually or simultaneously include both electrically insulating materials (e.g., dielectrics) and conductive materials (e.g., metals). For example, during a single polishing step involving chemical mechanical planarization (CMP) of the barrier layer, polishing pads may be needed to remove metals (e.g., copper), and / or adhesive / barrier layers and / or capping layers (e.g., tantalum and tantalum nitride), and / or dielectric materials (e.g., inorganic materials such as oxides of polysiloxane or other glasses). Due to the differences in material properties and polishing characteristics between the dielectric layer, metal layer, adhesive / barrier and / or capping layers, coupled with the feature size of the wafer to be polished, the requirements for polishing pads can be extremely high.

[0005] In CMP polishing, polymeric polishing pads are often used in combination with abrasive inorganic slurries to remove the desired material from the substrate. Conventional polishing pads for CMP are based on foams, but micro-replicating polishing pads have recently been developed. For these micro-replicating polishing pads in particular, faster removal rates are desirable to increase the throughput of CMP processes.

[0006] Typically, polishing pad materials with controlled hardness are desirable for consistent performance. However, during the polishing process, the pad temperature can increase, at least in part, due to friction between the pad and the substrate. Because of the polymeric nature of the material, this temperature increase leads to a decrease in the modulus and hardness of the pad material. This reduction in hardness and modulus can cause undesirable variations in polishing performance. Consequently, polishing pad materials that mitigate or eliminate the reduction in hardness and modulus are desirable.

[0007] Among the various classes of polymers that can be used in polishing pads, urethane materials are particularly useful for CMP polishing applications, at least in part because of their toughness. Conventionally, modulus increases of urethanes above about 30 MPa are achieved by increasing their hard segment content. This increase in hard segment content provides room temperature moduli within the target range of 30 MPa to 1000 MPa, but this typically requires increasing the glass transition temperature to near the glass transition point of 25°C. Glass transition inherently involves a significant modulus change with temperature, which is undesirable for CMP applications when it approaches 25°C. Therefore, the general approach of using hard segment content with a modulus close to 30 MPa to 1000 MPa is suboptimal for the preparation of CMP pads with consistent polishing performance.

[0008] The degree of change in material modulus with temperature can be quantified by dividing the tensile modulus at 25°C (E'25) by the tensile modulus at 60°C (E'60). This tensile modulus can be determined using a dynamic mechanical analysis (DMA) temperature ramp test. In the DMA temperature ramp test, polymeric materials often exhibit a glassy plateau, where the modulus is relatively stable over a significant temperature range. The typical modulus seen in the glassy plateau range falls between approximately 3000 MPa and 1000 MPa. Polymeric materials also often exhibit a rubbery plateau range over a significant temperature range. The typical modulus seen in the rubbery plateau range falls between approximately 1 MPa and 30 MPa. Between the glassy and rubbery plateau ranges, the polymeric material often exhibits a relatively rapid modulus transition with temperature (e.g., glass transition or melt transition). As a result, the material identification system of the working layer of the polishing pad with a relatively stable modulus in the temperature range of 25°C to 60°C is desired, wherein the modulus range is approximately 1000 MPa to 30 MPa (which is generally a transition modulus level).

[0009] Generally speaking, this disclosure concerns the discovery of such materials. In this regard, it has been found that certain blends of thermoplastic polyurethanes containing certain styrene polymers can produce polishing pads with a relatively stable modulus between 25°C and 60°C, while having a modulus in this temperature range between about 30 MPa and 1000 MPa. [Definitions]

[0010] As used herein, the singular forms "a / an" and "the" include a plurality of referents unless expressly indicated otherwise in the text. As used in this specification and the accompanying embodiments, the term "or" is generally used to include the meaning of "and / or" unless expressly indicated otherwise in the text.

[0011] As used in this document, the range of numbers described by endpoints includes all numbers falling within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.8, 4, and 5).

[0012] Unless otherwise indicated, all numerical values, measurements of attributes, and so on, expressed in this specification and embodiments, should in all cases be understood to be modified with the term "about." Therefore, unless otherwise indicated, the numerical parameters presented in the foregoing specification and the accompanying list of embodiments may vary according to the desired properties that a person skilled in the art would attempt to obtain using the teachings of this disclosure. At least, the numerical parameters should be interpreted in light of the number of significant digits and by applying common rounding techniques, but this is not intended to limit the application of the equivalence theory of the claimed embodiments.

[0013] "Working surface" refers to the surface of the polishing pad that is adjacent to and at least partially in contact with the surface of the substrate being polished.

[0014] A "pore" refers to a cavity within the working surface of a pad that allows a fluid, such as a liquid, to remain. A pore allows at least a portion of the fluid to remain inside and not flow out.

[0015] "Precisely shaped" refers to a shape feature, such as a protrusion or hole, that has a molded shape that is the opposite of the shape corresponding to a cavity or protrusion, and that shape is maintained after the shape feature is removed from the mold.

[0016] "Micro-replication" refers to a manufacturing technique in which precisely shaped morphological features are prepared by casting or molding a polymer (or a polymer precursor that is later cured to form the polymer) in a production tool, such as a mold or embossing tool, where the production tool has a plurality of morphological features ranging from micrometers to millimeters in size. When the polymer is removed from the production tool, a series of morphological features appear on the surface of the polymer. The morphological features on the polymer surface have shapes that are opposite to the original features of the production tool. The micro-replication manufacturing technique disclosed herein essentially results in the formation of a micro-replicated layer (i.e., a textured polished layer) that includes micro-replicated protrusions (i.e., precisely shaped protrusions) when the production tool has cavities, and micro-replicated holes (i.e., precisely shaped holes) when the production tool has protrusions. If the production tool includes both cavities and protrusions, the micro-replicated layer (textured polished layer) will simultaneously have micro-replicated protrusions (i.e., precisely shaped protrusions) and micro-replicated holes (i.e., precisely shaped holes).

[0017] "Thermoplastic polyurethane" refers to polyurethane that becomes liquid upon heating, such as in a temperature range of 100°C to 250°C. Thermoplastic polyurethane is preferably uncrosslinked, and in its liquid state, the tan δ value measured by dynamic mechanical analysis (DMA) becomes greater than 1.0. At cooler temperatures (such as below 100°C), thermoplastic polyurethane becomes solid, and the tan δ value measured by DMA is less than 1.0. Thermoplastic polyurethane can be prepared by reacting monomers with functionalities in appropriate ratios so that the polymer does not form a gel. In systems containing only bifunctional and monofunctional monomers, the polymer is not expected to form a gel. Systems containing trifunctional or higher-functional monomers may form a gel.

[0018] This disclosure relates to articles, systems, and methods for polishing substrates, including but not limited to semiconductor wafers.

[0019] In some embodiments, this disclosure relates to a polishing pad that can be formed as a multilayer structure having a working layer (i.e., the layer intended to contact the substrate to be polished) and one or more additional layers (e.g., sub-pad layers, foam layers), which are coupled to each other via suitable fastening mechanisms (e.g., adhesives). In some embodiments, the working layer of this disclosure may be a textured polishing layer. Although not intended to be limiting, this disclosure primarily relates to two types of textured polishing layers: micro-replicated polishing layers and porous foam polishing layers.

[0020] Referring now to Figures 1A to 1C, in some embodiments, this disclosure relates to a textured polished layer comprising a plurality of precision-formed holes and / or a plurality of precision-formed bumps (such a polished layer may also refer herein to a micro-replicated polished layer). Figure 1A shows a schematic cross-sectional view of a portion of a textured polished layer 10 according to some embodiments of this disclosure. The textured polished layer 10 includes a working surface 12 (i.e., the surface of the polished layer 10 intended to contact the substrate to be polished) and a second surface 13 opposite to the working surface 12. The working surface 12 may be a precision-engineered surface having a precision-engineered morphology. The working surface 12 may include a plurality of precision-formed holes 16 or a plurality of precision-formed bumps 18 having distal ends 18b. A platform region 14 is located in the region between the precision-formed holes 16 and the precision-formed bumps 18 and may be considered part of the working surface. The textured layer 10 may also include a megachannel 19.

[0021] The shape of the precision-formed hole 16 is not specifically limited and includes, but is not limited to, cylinders, hemispheres, cubes, rectangular prisms, triangular prisms, hexagonal prisms, triangular pyramids, 4, 5, and 6-sided pyramids, truncated pyramids, cones, truncated cones, and the like. The lowest point of the precision-formed hole 16 measured from the platform region is considered the bottom of the hole. The intersection of the precision-formed hole sidewall 16a and the platform region 14 is considered the top of the hole. All precision-formed holes 16 may have the same shape or may use combinations of shapes. The longest dimension of the precision-formed hole 16 in the plane of the platform region 14 (e.g., the diameter when the shape of the precision-formed hole 16 is cylindrical) may be less than about 10 mm, less than about 5 mm, less than about 1 mm, less than about 500 micrometers, less than about 200 micrometers, less than about 100 micrometers, less than about 90 micrometers, less than about 80 micrometers, less than about 70 micrometers, or even less than about 60 micrometers.

[0022] The depth of the precision-formed holes 16 can be less than about 5 mm, less than about 1 mm, less than about 500 micrometers, less than about 200 micrometers, less than about 100 micrometers, less than about 90 micrometers, less than about 80 micrometers, less than about 70 micrometers, or even less than about 60 micrometers. The precision-formed holes 16 can be uniformly distributed across the surface of the textured polished layer 10 (i.e., have a single areal density), or they can have different areal densities across the surface of the textured polished layer 10. The areal density of the precision-formed hole 16 can be less than about 1,000,000 / mm2, less than about 500,000 / mm2, less than about 100,000 / mm2, less than about 50,000 / mm2, less than about 10,000 / mm2, less than about 5,000 / mm2, less than about 1,000 / mm2, less than about 500 / mm2, less than about 100 / mm2, less than about 50 / mm2, less than about 10 / mm2, or even less than about 5 / mm2.

[0023] The precision-formed holes 16 can be randomly arranged across the surface of the textured polished layer 10, or can be arranged into a pattern across the textured polished layer 10. The patterns include, but are not limited to, square arrays, hexagonal arrays, and the like. Combinations of patterns can be used.

[0024] The shape of the precision-formed protrusion 18 is not specifically limited, and includes, but is not limited to, cylinders, hemispheres, cubes, rectangular prisms, triangular prisms, hexagonal prisms, triangular pyramids, 4, 5, and 6-sided pyramids, truncated pyramids, cones, truncated cones, and the like. The intersection of the precision-formed protrusion sidewall 18a and the platform region 14 is considered the base of the protrusion. The highest point of the precision-formed protrusion 18 measured from the platform region is considered the top of the protrusion. The height of the precision-formed protrusion is considered to be from the base of the protrusion to the top of the protrusion. All precision-formed protrusions 18 may have the same shape, or combinations of shapes may be used.

[0025] The longest dimension of the precision forming protrusion 18 in the plane of platform region 14 (e.g., the diameter when the shape of the precision forming protrusion 18 is cylindrical) may be less than about 10 mm, less than about 5 mm, less than about 1 mm, less than about 500 micrometers, less than about 200 micrometers, less than about 100 micrometers, less than about 90 micrometers, less than about 80 micrometers, less than about 70 micrometers, or even less than about 60 micrometers. The height of the precision forming protrusion 18 may be less than about 5 mm, less than about 1 mm, less than about 500 micrometers, less than about 200 micrometers, less than about 100 micrometers, less than about 90 micrometers, less than about 80 micrometers, less than about 70 micrometers, or even less than about 60 micrometers. The height of the precision forming protrusion 18 may be greater than about 1 micrometer, greater than about 5 micrometers, greater than about 10 micrometers, greater than about 15 micrometers, or even greater than about 20 micrometers. All precision forming protrusions 18 may have the same height, or the heights of different precision forming protrusions 18 or groups of precision forming protrusions 18 may be different.

[0026] The precision-formed hole protrusions 18 may be uniformly distributed across the surface of the textured polished layer 10 (i.e., have a single areal density), or may have different areal densities across the surface of the textured polished layer 10. The areal density of the precision-formed protrusions 18 may be less than about 1,000,000 / mm², less than about 500,000 / mm², less than about 100,000 / mm², less than about 50,000 / mm², less than about 10,000 / mm², less than about 5,000 / mm², less than about 1,000 / mm², less than about 500 / mm², less than about 100 / mm², less than about 50 / mm², less than about 10 / mm², or even less than about 5 / mm². The areal density of the precisely formed protrusion 18 can be greater than about 1 / dm2, greater than about 10 / dm2, greater than about 100 / dm2, greater than about 5 / cm2, greater than about 10 / cm2, greater than about 100 / cm2, or even greater than about 500 / cm2.

[0027] The precisely shaped protrusions 18 can be randomly arranged across the surface of the textured polished layer 10, or can be arranged into a pattern across the textured polished layer 10. The pattern includes, but is not limited to, a square array, a hexagonal array, and the like. Combinations of patterns can be used.

[0028] The textured polishing layer may include one or more megachannels or megagrooves (e.g., megachannel 19 of Figures 1A-1C). The megachannels provide an improved polishing solution distribution and facilitate chip removal from the polishing pad. Unlike orifices, megachannels or megagrooves do not allow fluid to remain within them indefinitely; fluid can flow out of the megachannels during pad use. The megachannels are generally wide and their depth is greater than that of a precisely shaped orifice. The width of such megachannels may be greater than about 10 micrometers, greater than about 50 micrometers, or even greater than about 100 micrometers. The width of such megachannels may be less than about 10 mm, less than about 5 mm, less than about 2 mm, less than about 1 mm, less than about 500 micrometers, or even less than about 200 micrometers. The depth of such megachannels may be greater than about 50 micrometers, greater than about 100 micrometers, greater than about 500 micrometers, or even greater than about 1,000 micrometers. In some embodiments, the depth of such megachannels is not greater than the thickness of the textured polishing layer. The depth of these megachannels can be less than about 10 mm, less than about 5 mm, less than about 2.5 mm, or even less than about 1 mm. These megachannels can be formed into the textured polished layer using any technique known in the art (including, but not limited to, machining). In some embodiments, the megachannels are manufactured in an embossing process for forming precise shaped holes and / or protrusions. This is achieved by forming negatives (i.e., raised areas) in a master tool, followed by the formation of the megachannels themselves in the textured polished layer during embossing. The megachannels can be manufactured to form various patterns known in the art, including, but not limited to, concentric rings, parallel lines, radial lines, a series of lines forming a grid array, spirals, and the like. Combinations of different patterns can be used.

[0029] The working surface of the textured polishing layer may further include nanometer-sized topographical features on the surface of the textured polishing layer. As used herein, a "nanometer-sized topographical feature" refers to a regular or irregular shape domain having a length or longest dimension not exceeding about 1,000 nm. In some embodiments, precision-formed bumps, precision-formed holes, plateau regions, or any combination thereof include nanometer-sized topographical features on their surfaces. In one embodiment, precision-formed bumps, precision-formed holes, and plateau regions include nanometer-sized topographical features on their surfaces. This additional topography is believed to enhance the hydrophilicity of the pad surface, which is believed to improve slurry distribution, wettability, and retention across the polishing pad surface. Nanometer-sized topographical features can be formed by any method known in the art, including but not limited to plasma processing such as plasma etching and wet chemical etching. Plasma treatment includes the procedures described in the following documents: U.S. Patent No. 8,634,146 (David et al.) and U.S. Provisional Application No. 61 / 858670 (David et al.), the entire contents of which are incorporated herein by reference.

[0030] In some embodiments, the nanoscale features may be regular shape domains, i.e., domains with clearly defined shapes such as circles, squares, hexagons, and the like, or the nanoscale features may be irregular shape domains. Domains may be configured as regular arrays, such as hexagonal arrays or square arrays, or they may be random arrays. In some embodiments, the nanoscale topography features on the working surface of the textured polished layer may be a random array of irregular shape domains. One advantage of including nanoscale topography features on the surfaces of the precision forming protrusions and precision forming holes, and / or the plateau regions is that if the nanoscale topography features wear away from the surface of the protrusions during the polishing process (see FIG. 1C), the cross-pad surface, i.e., the working surface of the textured polished layer, can be maintained, including the positive benefits of nanoscale topography features that enhance hydrophilicity, because the nanoscale topography features will not wear away from the surfaces of the precision forming holes and / or the plateau regions during polishing. Therefore, even if the surface of the precision-formed protrusions in contact with the polished substrate (i.e., the distal end of the precision-formed protrusions) may have poor wetting properties, a textured polished layer with surprisingly good surface wetting properties can still be obtained.

[0031] In some embodiments, surface modification techniques that form nanoscale morphological features may be used to chemically alter or modify the working surface of a textured polished layer. The modified portion of the working surface of the textured polished layer (e.g., including nanoscale morphological features) may be referred to as a secondary surface layer. The unmodified portion of the textured polished layer may be referred to as the host layer. Figure 1B shows a textured polished layer 10', which is almost identical to that of Figure 1A, except that the textured polished layer 10' includes a secondary surface layer 22 and a corresponding host layer 23. In this embodiment, the working surface includes a secondary surface layer 22 (i.e., the area where the surface has been chemically modified) and a host layer 23 (i.e., the area where the working surface of the adjacent secondary surface layer has not been chemically modified). As shown in Figure 1B, the distal end 18b of the precision-formed protrusion 18 is modified to include the secondary surface layer 22. In some embodiments, the chemical composition of at least a portion of the secondary surface layer 22 differs from that of the main body layer 23. For example, the chemical composition of the polymer in at least a portion of the outermost surface of the working surface is modified, while the polymer beneath the modified surface has not yet been modified. Surface modification may include those known in the field of polymer surface modification technology, including chemical modification using various polar atoms, molecules, and / or polymers.

[0032] In some embodiments, the hardness of the textured polished layer 10 may be greater than about 20 Shore D, greater than about 30 Shore D, or even greater than about 40 Shore D. The hardness of the textured polished layer 10 may be less than about 90 Shore D, less than about 80 Shore D, or even less than about 70 Shore D. The hardness of the textured polished layer 10 may be greater than about 20 Shore A, greater than about 30 Shore A, or even greater than about 40 Shore A. The hardness of the textured polished layer 10 may be less than about 95 Shore A, less than about 80 Shore A, or even less than about 70 Shore A.

[0033] In some embodiments, the micro-replicated textured polished layer disclosed herein may be of the type described in U.S. Patent No. 10,071,461, the entire contents of which are incorporated herein by reference.

[0034] In some alternative embodiments, the textured polishing layer disclosed herein can be formed as a semi-rigid or rigid microporous material (e.g., a foam). Such polishing layers may have any or all of a porosity between 10% and 90%, between 30% and 70%, or between 40% and 60%. Such polishing layers may have a hardness between 0 Shore A and 100 Shore D, or between 40 Shore A and 75 Shore D. Such polishing layers may have an average pore size between 1 μm and 200 μm, or between 30 μm and 60 μm. In some embodiments, this type of polishing pad may be produced as an extruded foam.

[0035] In some embodiments, the semi-rigid or rigid microporous textured polishing layer disclosed herein may further include at least one channel having a depth greater than the distance by which the foaming features extend from or into the first master surface of the textured polishing layer. The channel provides improved polishing solution distribution, flexibility of the polymeric foam layer, and facilitates chip removal from the polishing pad. In some embodiments, the channel does not allow fluid to remain within it indefinitely (i.e., fluid can flow out of the channel during pad use). The width of the channel may be greater than about 10 micrometers, greater than about 50 micrometers, or even greater than about 100 micrometers. The width of the channel may be less than about 10 mm, less than about 5 mm, less than about 2 mm, less than about 1 mm, less than about 500 micrometers, or even less than about 200 micrometers. The depth of the channel may be greater than about 50 micrometers, greater than about 100 micrometers, greater than about 500 micrometers, or even greater than about 1,000 micrometers. In some embodiments, the depth of the channel is not greater than the thickness of the textured polishing layer. The depth of these channels may be less than about 10 mm, less than about 5 mm, less than about 2.5 mm, or even less than about 1 mm. These channels may be formed into the textured polished layer by any technique known in the art (including but not limited to machining, embossing, and molding).

[0036] In some embodiments, the textured polished layer disclosed herein may be formed by a polymeric blend comprising at least one thermoplastic carbamate and a styrene copolymer.

[0037] In some embodiments, suitable thermoplastic polyurethanes include aromatic polyester polyurethanes, aromatic polyether polyurethanes, aliphatic polyester polyurethanes, or aliphatic polyether polyurethanes. Suitable thermoplastic polyurethanes may have a weight average molecular weight (Mw) of 25,000 to 400,000 g / mol or 40,000 to 200,000 g / mol, as determined, for example, by gel permeation chromatography (GPC) using polystyrene standards.

[0038] In some embodiments, available thermoplastic polyurethanes include, for example, those marketed under the following trademarks: ESTANE, PELLETHANE, and PEARLTHANE from Lubrizol Advanced Materials, Inc., Cleveland, Ohio; AVALON, IROGRAN, and KRYSTALGRAN from Huntsman Polyurethanes (an international business unit of Huntsman International LLC), The Woodlands, Texas; ELASTOLLAN from BASF Corporation, Florham Park, NJ; and TEXIN from Covestro Corporation, Pittsburgh, Pennsylvania.

[0039] In some embodiments, thermoplastic polyurethane may be a reaction product of, for example, a first resin comprising at least two isocyanate groups and a second resin having at least two groups that react with the isocyanate groups.

[0040] In some embodiments, the first resin comprising at least two isocyanate groups is selected from isocyanate functional monomers, isocyanate functional prepolymers, and combinations thereof. In some embodiments, the second resin having at least two groups that react with the isocyanate groups is selected from a wide variety of materials. In some embodiments, the second resin has functional groups selected from hydroxyl, mercapto, primary amine, secondary amine, and combinations thereof.

[0041] In some embodiments, a particularly suitable thermoplastic material may be a reaction product of a first resin comprising, for example, 4,4'-diphenylmethane diisocyanate or a prepolymer made of 4,4'-diphenylmethane diisocyanate, and a second resin comprising 1,4-butanediol, poly(tetramethylene ether) glycol, polyester polyol, and mixtures thereof.

[0042] In some embodiments, the thermoplastic polyurethane disclosed herein may be a reaction product of the resin described in U.S. Patent Application Publication No. 2013 / 0012108, the entire contents of which are incorporated herein by reference.

[0043] In some embodiments, a suitable styrene copolymer may include (or substantially consist of) styrene-acrylonitrile copolymer (SAN) or acrylonitrile-butadiene-styrene copolymer (ABS). In some embodiments, a suitable styrene copolymer has at least 10%, at least 30%, or at least 50% styrene by weight of the copolymer monomer units. In some embodiments, a suitable styrene copolymer has at least 5%, at least 10%, or at least 20% acrylonitrile by weight of the copolymer monomer units.

[0044] In some embodiments, the thermoplastic carbamates may be present in the textured polished layer in an amount between 40 and 95 wt.%, 50 and 90 wt.%, or 55 and 85 wt.%, based on the total weight of the textured polished layer; and the styrene copolymer may be present in the textured polished layer in an amount between 5 and 60 wt.%, 10 and 50 wt.%, or 15 and 45 wt.%, based on the total weight of the textured polished layer.

[0045] In some embodiments, the styrene copolymer may exist in a region separate from the thermoplastic carbamate, such that both the glass transition temperature of the carbamate and the glass transition temperature of the styrene copolymer are present in the material. When the glass transition of the carbamate is below 25°C and the glass transition of the styrene polymer is above 60°C, a flat-line modulus is established between 25°C and 60°C, wherein the carbamate material is in its rubber-like flat-line region and the styrene material is in its glass-like flat-line region. This results in a modulus for phase-separated blended materials in the intermediate range of approximately 30 MPa to 1000 MPa at a frequency of 1 Hz, between 25°C and 60°C.

[0046] In embodiments of the texturized polishing layer system of micro-replicated polishing layers, the size of these styrene domains can be in the range significantly smaller than the longest dimension of the micro-replicated features (e.g., precisely shaped holes or protrusions) existing on the working surface of the texturized polishing layer. For example, in some embodiments, the average size of these styrene domains (in terms of the average longest dimension) can range from 0.5 to 40 micrometers, 1 to 20 micrometers, or 1 to 10 micrometers. In this way, each micro-replicated feature will contain multiple styrene domains, such that the average composition of each micro-replicated feature will be similar. Furthermore, it should be understood that the composition of each micro-replicated feature will remain fairly constant as the feature wears down with use. In contrast, if the discrete domains of the polymer blend are larger, making the size more similar to the size of the micro-replicated feature, then each feature will contain only a few large, harder domains or no harder domains at all. This can result in feature-to-feature variable hardness, which is undesirable for consistent polishing performance and defect minimization.

[0047] In some embodiments, the polymeric dopant of the textured polished layer may have an E'25 / E'60 of less than 4.5, less than 3.0, or less than 2.5 and greater than 1 or greater than 1.2; and a tensile modulus of 1 Hz at a frequency between 10 MPa and 1000 MPa, 30 MPa and 1000 MPa, or 70 and 800 MPa in a temperature range of 25°C to 60°C.

[0048] In some embodiments, the textured polishing layer 10 is substantially free of any inorganic abrasive material (e.g., abrasive particles), i.e., it is an abrasive-free polishing pad. "Substantially free" means that the textured polishing layer 10 includes less than about 10% by volume, less than about 5% by volume, less than about 3% by volume, less than about 1% by volume, or even less than about 0.5% by volume of inorganic abrasive particles. In some embodiments, the textured polishing layer 10 is substantially free of inorganic abrasive particles. An abrasive material can be defined as a material having a Mohs hardness greater than that of the abraded or polished substrate. An abrasive material can be defined as having a Mohs hardness greater than about 5.0, greater than about 5.5, greater than about 6.0, greater than about 6.5, greater than about 7.0, greater than about 7.5, greater than about 8.0, or even greater than about 9.0.

[0049] There are no particular limitations on the thickness of the textured polishing layer, except that the thickness can be consistent with the required thickness to allow polishing on a suitable polishing tool. In some embodiments, the thickness of the textured polishing layer can be greater than about 25 micrometers, greater than about 50 micrometers, greater than about 100 micrometers, or even greater than 250 micrometers; less than about 20 mm, less than about 10 mm, less than about 5 mm, or even less than about 2.5 mm. There are no particular limitations on the shape of the textured polishing layer. The layer can be manufactured such that its shape conforms to the shape of the corresponding table of the polishing tool to which the pad will be attached during use. Shapes such as circular, square, hexagonal, and similar shapes can be used. There are no particular limitations on the maximum size of the textured polishing layer (e.g., the diameter of a circular layer). The maximum size of the layer can be greater than about 10 cm, greater than about 20 cm, greater than about 30 cm, greater than about 40 cm, greater than about 50 cm, greater than about 60 cm; less than about 2.0 meters, less than about 1.5 meters, or even less than about 1.0 meter.

[0050] Figure 2 shows a polishing pad 50, which includes: a textured polishing layer 10 having a working surface 12 and a second surface 13 opposite to the working surface 12; and a sub-pad 30 adjacent to the second surface 13. Optionally, a foam layer 40 is inserted between the second surface 13 of the textured polishing layer 10 and the sub-pad 30. The various layers of the polishing pad can be bonded together by any technique known in the art, including the use of adhesives such as pressure-sensitive adhesives (PSA), hot melt adhesives, and in-situ curing adhesives. A lamination process using PSA, such as PSA transfer tape, is a specific procedure for bonding the various layers of the polishing pad 50. The sub-pad 30 can be any of those known in the art. The sub-pad 30 can be a single layer of a relatively rigid material, such as polycarbonate, or a single layer of a relatively compressible material, such as an elastic foam. The sub-pad 30 can also have two or more layers and may include a substantially rigid layer and a substantially compressible layer. The foam layer 40 may have a hardness between about 20 Shore D and about 90 Shore D. The foam layer 40 may have a thickness between about 125 micrometers and about 5 mm, or even between about 125 micrometers and about 1,000 micrometers.

[0051] In some embodiments, the pad (including a textured polishing layer, a sub-pad, an optional foam layer, or any combination thereof) may include a window (i.e., an area that allows light to pass through so that standard endpoint detection techniques can be used in the polishing process (e.g., wafer endpoint detection)). The polishing pad disclosed herein can be manufactured to operate on such tools and endpoint detection windows, and can be configured to work in conjunction with an endpoint detection system of a polishing tool that may be included in the polishing pad.

[0052] In some embodiments, this disclosure relates to a polishing system comprising any of the aforementioned polishing pads or pad layers and a polishing solution. The polishing pad may include any of the previously disclosed texturized polishing layers 10. The polishing solution used is not particularly limited and may be any known in the art. In some embodiments, the polishing solution is a slurry, i.e., a liquid containing organic or inorganic abrasive particles or combinations thereof. The concentration of organic or inorganic abrasive particles or combinations thereof in the polishing solution is not particularly limited. The concentration of organic or inorganic abrasive particles or combinations thereof in the polishing solution may be greater than about 0.5%, greater than about 1%, greater than about 2%, greater than about 3%, greater than about 4%, or even greater than about 5% by weight; and less than about 30%, less than about 20%, less than about 15%, or even less than about 10% by weight. In some embodiments, the polishing solution is substantially free of organic or inorganic abrasive particles. "Substantially free of organic or inorganic abrasive particles" means that the polishing solution contains less than about 0.5%, less than about 0.25%, less than about 0.1%, or even less than about 0.05% by weight of organic or inorganic abrasive particles. In one embodiment, the polishing solution may not contain organic or inorganic abrasive particles. The polishing system may include polishing solutions (e.g., slurries) for silicon oxide CMP, including but not limited to shallow trench isolation CMP; polishing solutions (e.g., slurries) for metal CMP, including but not limited to tungsten CMP, copper CMP, and aluminum CMP; polishing solutions (e.g., slurries) for barrier CMP, including but not limited to tantalum and tantalum nitride CMP; and polishing solutions (e.g., slurries) for polishing hard substrates, such as sapphire. The polishing system may further include a substrate to be polished or ground.

[0053] Figure 3 schematically illustrates an example of a polishing system 100 used with polishing pads and methods according to some embodiments of the present disclosure. As shown, system 100 may include a polishing pad 150 and a polishing solution 160. The system may further include one or more of the following: a substrate 110 to be polished or ground, a platform 140, and a carrier assembly 130. An adhesive layer 170 may be used to attach the polishing pad 150 to the platform 140 and may be part of the polishing system. The polishing solution 160 may be a layer of solution disposed covering the main surface of the polishing pad 150. The polishing pad 150 includes a textured polishing layer (not shown) and optionally includes sub-pads and / or foam layers, as described with respect to the polishing pad 50 of Figure 2. The polishing solution is generally disposed on the working surface of the textured polishing layer of the polishing pad. The polishing solution may also be located at the interface between the substrate 110 and the polishing pad 150. During operation of the polishing system 100, the drive assembly 145 can rotate the platform 140 (arrow A) to move the polishing pad 150 for polishing. The polishing pad 150 and polishing solution 160 can define, individually or in combination, a polishing environment for mechanically and / or chemically removing material from or polishing the main surface of the substrate 110. To polish the main surface of the substrate 110 using the polishing system 100, the carrier assembly 130 can urge the substrate 110 against the polishing surface of the polishing pad 150 in the presence of polishing solution 160. The platform 140 (and thus the polishing pad 150) and / or the carrier assembly 130 then move relative to each other, causing the substrate 110 to translate across the polishing surface of the polishing pad 150. The carrier assembly 130 can rotate (arrow B) and optionally lateralize (arrow C). Thus, the textured polishing layer of the polishing pad 150 removes material from the surface of the substrate 110. In some embodiments, the textured polishing layer may include inorganic abrasive materials (e.g., inorganic abrasive particles) to facilitate material removal from the surface of the substrate. In other embodiments, the textured polishing layer substantially contains no inorganic abrasive material, and the polishing solution may substantially contain no organic or inorganic abrasive particles, or may contain organic or inorganic abrasive particles or a combination thereof. It should be understood that the polishing system 100 of FIG3 is merely an example of one polishing system that can be used in conjunction with the polishing pads and methods disclosed herein, and it should be understood that other known polishing systems may be used without departing from the scope of this disclosure.

[0054] In another embodiment, this disclosure relates to a method for polishing a substrate, the polishing method comprising: providing any of the aforementioned polishing pads or layers; providing a substrate; contacting the working surface of the polishing pad with the surface of the substrate; moving the polishing pad and the substrate relative to each other while maintaining contact between the working surface of the polishing pad and the surface of the substrate, wherein polishing is optionally performed in the presence of a polishing solution. In some embodiments, the polishing solution is a slurry and may include any of the aforementioned slurries. In another embodiment, this disclosure relates to a method for polishing any of the aforementioned substrates, wherein the substrate is a semiconductor wafer. The materials constituting the semiconductor wafer to be polished may include, but are not limited to, at least one of dielectric materials, conductive materials, barrier / adhesive materials, and capping materials. Dielectric materials may include, for example, inorganic dielectric materials such as polysiloxane and other glasses, and at least one of organic dielectric materials. Metallic materials may include, but are not limited to, at least one of copper, tungsten, aluminum, silver, and the like. Capping materials may include, but are not limited to, at least one of silicon carbide and silicon nitride. The barrier / adhesive material may include, but is not limited to, at least one of tantalum and tantalum nitride. Example

[0055] Unless otherwise stated or obvious from the context, all parts, percentages, ratios, etc. in the examples and the remainder of this specification are by weight. Test methods [General polymerization method for preparing Examples 7 to 36 (PE 7 to PE 36):]

[0056] This polymer blend was prepared by reactively mixing a mixture of polyol, chain extender, catalyst, isocyanate prepolymer, and styrene polymer. The reactive mixture was mixed in an MC15 micromixer (obtained from Xplore Instruments, Sittard, The Netherlands) at a temperature set between 200°C and 230°C for at least five minutes to allow polymerization to occur. The film was then pressurized using a hydraulic press at 375°F (191°C) to impart a film thickness between 0.3 mm and 0.8 mm. The formulation is based on weight. [Friction Testing Methods - Coefficients:]

[0057] The polymer blend membrane was secured to a horizontal polycarbonate platform with tape. A 201.6-gram stainless steel sled (2.5” × 2.5” × 0.24” (6.35cm × 6.35cm × 0.61cm) was placed on the membrane surface. One end of a cotton thread was attached to the sled. The other end of the thread was guided under a pulley and secured to the crosshead of an electromechanical testing system (MTS Criterion Model 43, MTS Systems Corporation, Eden Prairie, MN). The crosshead was then moved at a total displacement of 5 inches (13cm) at 1.2 inches / min (3.0cm / min), causing the sled to be pulled horizontally across the membrane surface for a distance of 5 inches (13cm). The average load between displacements of 1.0 and 4.0 inches (2.5 and 10.2cm) was divided by the weight of the sled to give the coefficient of friction (COF). [Shore D Hardness Test Method:]

[0058] A sample of the polymer blend film was folded onto itself until a total thickness of at least 1.5 mm was achieved. This folded stack was then placed on top of a 2.8 mm thick polyurethane sample with a hardness of 50 D, resulting in a total polyurethane stack of at least 4.2 mm. Before reading the hardness, a digital Shore D hardness tester (Phase II No. PHT-980, available from Cole Parmer, Vernon Hills, IL) was pressed onto the surface of the folded film and held for 2 seconds. Dynamic Mechanical Analysis (DMA) Test Method

[0059] The membrane sample was cut into strips 6.2 mm wide and approximately 4 cm long. The thickness of the membrane was measured. The membrane was mounted in an RSA-G2 DMA (TA Instruments, New Castle, DE, USA) tension fixture with an initial fixture spacing of 25 mm. The membrane sample was then tested at a rate of 3 °C per minute, with a temperature increase of at least -20 °C to 150 °C, under 0.1% strain and 1 Hz oscillation. The temperature at which the tan δ signal reached its maximum value was recorded as the glass transfer temperature. [Test Method for Polishing 300mm Oxide Wafers]

[0060] The wafer was polished using a CMP polisher, REFLEXION, available from Applied Materials, Inc. of Santa Clara, CA. This polisher was equipped with a 300mm CONTOUR head for holding 300mm diameter wafers. A 30.5-inch (77.5cm) diameter film sample was laminated onto a Poron sub-pad (available from Rogers Corporation, Chandler, AZ, 4701-60-20062004-54T-UR), and this pad assembly was laminated onto a polishing tool platform with a PSA layer. The pad broke during a 2-minute break-in period at 12psi (83kPa). CONTOUR head pressure, platform, and head RPM are shown in Table 1. The wafer was then polished at 3psi for 1 minute. A 4.25mm diameter brush-type pad conditioner (3M CMP PAD CONDITIONER BRUSH PB33A, purchased from 3M Company, St. Paul, Minnesota) was mounted on the conditioning arm and used at a speed of 108 rpm and a downforce of 3 lbf. The pad conditioner was used to sweep the entire pad surface sinusoidally at 19 swp / min, achieving 100% in-situ conditioning.

[0061] The polishing solution was SEIMICRON CES-333F-2.5, a slurry purchased from Asahi Glass Co., LTD, Tokyo, Japan. Before use, the SEIMICRON CES-333F-2.5 slurry was diluted with DI water to achieve a final volume ratio of 1 / 3. The TOx monitoring wafer was polished for 1 minute and then measured. The average of four or five rate wafers was recorded. The 300mm diameter TOx monitoring wafer was obtained from Advantiv Technologies Inc., Fremont, California. The wafer stack was as follows: 300mm main Si substrate + 20KA thermal oxide. Twenty rate oxide wafers were used as "dummy wafers" between monitoring wafer polishing sessions, each polished for 1 minute. Four to five rate wafers were then polished.

[0062] The removal rate is calculated by determining the thickness variation of the polished oxide layer. This thickness variation is divided by the wafer polishing time to obtain the removal rate of the polished oxide layer. Thickness measurements for 300mm diameter wafers were obtained using a NovaScan 3090Next 300, available from Nova Measuring Instruments, Rehovot, Israel. A 65-point diameter scan with 2mm edge exclusion was used. [Preparation Example]

[0063] Preparation and testing examples 1 to 30 (PE 1 to PE 30) are shown in Tables 1 to 5. The measured properties demonstrate how the SAN blend affects the modulus and modulus stability between 25°C and 60°C. PE 1, PE 2, PE 3, PE 5, and PE 6 were prepared by pressing films from the received materials. PE 4 was formed by standard melt mixing.

[0064] Preparation and testing examples 31 to 36 are shown in Table 6. The measured properties demonstrate how SAN and ABS affect the modulus and modular stability between 25°C and 60°C, compared to blends with other polymers. Domain sizes in preparation examples 31 to 36 were analyzed using scanning electron microscopy. Membrane samples were immersed in liquid nitrogen and then ruptured. The ruptured samples were then immersed in MEK for 30 minutes to dissolve SAN, ABS, and polystyrene. The ruptured surfaces were then imaged, and domain sizes were indicated by the remaining voids. In the case of polyethylene, polyethylene domains were visible in the images without dissolution. Domains from ABS and SAN were approximately between 1 and 5 micrometers, smaller than those from polyethylene and polystyrene, showing a substantial fraction of domains larger than 5 micrometers. Polyvinylpyrrolidone did not show any discrete domains.

[0065] Preparation Examples 37 and 38 were prepared by blending Lustran SAN 31 and Estane 58277 in a twin-screw extruder (model DTEX58, from David Standard, Pawcatuck, CT) at a melt temperature between 400℉ (204℃) and 480℉ (249℃) and an L / D of 42.5, operated at a screw speed of 300 RPM. The resulting polymer melt systems were granulated using an underwater granulator. For Example 37, 10 wt% Lustran SAN 31 was blended with 90 wt% Estane 58277. The resulting blend had an E'25 of 58.4 MPa, an E'60 of 28.8 MPa, and an E'25 / E'60 ratio of 2.03. For Example 38, 30 wt% Lustran SAN 31 was blended with 70 wt% Estane 58277. The resulting blend has an E'25 of 118.2 MPa, an E'60 of 60.6 MPa, and an E'25 / E'60 ratio of 1.95. Example

[0066] The micro-replicated CMP pads were prepared by embossing a polyurethane-based material using a procedure similar to that described in Example 2 of U.S. Patent No. 10,071,461 (which is incorporated herein by reference). The polished layer of Example 1 was made of Pellethane 5855 70D. Based on NMR analysis, Pellethane 5855 70D is a blend of 50 wt% SAN resin and 50 wt% polyurethane. The polished layers of Examples 2, 4, and 5 were produced by reactively extruding the formulation (see Table 7) in a co-rotating twin-screw extruder as described in Example 1 of U.S. Patent No. 8,128,779 (which is incorporated herein by reference). Comparative Example 3 (CE 3) is a commercially available foam-based CMP pad, obtained from the IC1010 pad of Dow Chemical Company, Midland, MI. The pads were tested according to the previously described 300mm oxide wafer polishing test method. The oxide removal rate results are summarized in Table 8. Examples 7 and 8 were prepared using Preparation Examples 37 and 38, respectively.

Claims

1. A polishing pad comprising: a textured polishing layer including a working surface and a second surface opposite to the working surface; wherein the textured polishing layer includes a polymeric blend comprising, by weight of the textured polishing layer, an amount of thermoplastic carbamate between 40 wt.% and 95 wt.% and a amount of styrene copolymer between 5 wt.% and 60 wt.%, wherein the styrene copolymer is present in a domain separate from the thermoplastic carbamate, such that both the glass transition temperature of the thermoplastic carbamate and the glass transition temperature of the styrene copolymer are present in the polymeric blend.

2. The polishing pad of claim 1, wherein the styrene copolymer comprises a styrene-acrylonitrile polymer or an acrylonitrile-butadiene-styrene copolymer.

3. The polishing pad of claim 1, wherein the polymeric blend has an E'25 / E'60 of less than 3.0 as measured by DMTA at 1 Hz in a temperature range of 25°C to 60°C and a tensile modulus between 30 MPa and 1000 MPa.

4. The polishing pad of claim 1, wherein the working surface includes a plurality of precision-formed holes, a plurality of precision-formed protrusions, or a plurality of precision-formed protrusions and a plurality of precision-formed holes.

5. The polishing pad of claim 1, wherein the textured polishing layer is formed as a material having a porosity between 30% and 70%.

6. The polishing pad of claim 1, further comprising a sub-pad, wherein the second surface of the textured polishing layer is adjacent to the sub-pad.

7. The polishing pad of claim 6 further comprises a foam layer, wherein the foam layer is inserted between the second surface of the textured polishing layer and the sub-pad.

8. A polishing system comprising a polishing pad as claimed in claim 1 and a polishing solution.

9. The polishing system of claim 8, wherein the polishing solution is a slurry.

10. A method for polishing a substrate, the method comprising: providing a polishing pad as claimed in claim 1; providing a substrate; contacting the working surface of the polishing pad with the surface of the substrate; moving the polishing pad and the substrate relative to each other while maintaining contact between the working surface of the polishing pad and the surface of the substrate, wherein polishing is performed in the presence of a polishing solution.

11. The method for polishing a substrate as claimed in claim 10, wherein the polishing solution is a slurry.

12. The method of polishing a substrate as claimed in claim 10, wherein the substrate is a semiconductor wafer.

13. The method of polishing a substrate as claimed in claim 12, wherein the surface of the semiconductor wafer to be polished includes at least one of a dielectric material and a conductive material.

Images