POLISHING PADS WITH IMPROVED PLANARIZATION EFFICIENCY
Embodiments of the disclosure include a polishing pad for planarizing a surface of a substrate during a polishing process. The polishing pad includes a base layer, comprising a first material composition, and a polishing layer disposed over the base layer. The polishing layer includes a second material composition that is exposed at a polishing surface of the polishing pad, wherein the polishing surface is configured to contact the surface of the substrate during the polishing process. The second material composition includes a polishing layer material having a hardness that is greater than 50 on a Shore D scale, a yield point strength, a yield point strength strain, a break point strength, and an elongation at break point strain, wherein a magnitude of a difference between the elongation at break point strain and the yield point strength strain is greater than the magnitude of yield point strength strain when measured at room temperature.
This application claims the benefit of U.S. provisional patent application Ser. No. 63/341,878, filed May 13, 2022 and U.S. provisional patent application Ser. No. 63/406,166, filed Sep. 13, 2022, which are both herein incorporated by reference.
BACKGROUND FieldEmbodiments of the present disclosure generally relate to polishing pads, and methods of manufacturing polishing pads, and more particularly, to polishing pads used for chemical mechanical polishing (CMP) of a substrate in an electronic device fabrication process.
Description of the Related ArtChemical mechanical polishing (CMP) is commonly used in the manufacturing of high-density integrated circuits to planarize or polish a layer of material deposited on a substrate. A CMP process includes contacting the material layer to be planarized with a polishing pad and moving the polishing pad, the substrate, or both, to create relative movement between the material layer surface and the polishing pad, in the presence of a polishing fluid including abrasive particles, chemically active components, or both.
One common application of a CMP process in semiconductor device manufacturing is planarization of a bulk film, for example pre-metal dielectric (PMD) or interlayer dielectric (ILD) polishing, where underlying two or three-dimensional features create recesses and protrusions in the to be planarized material surface. Other common applications of CMP processes in semiconductor device manufacturing include shallow trench isolation (STI) and interlayer metal interconnect formation, where the CMP process is used to remove the via, contact, or trench fill material (overburden) from the exposed surface (field) of the material layer having the STI or metal interconnect features disposed therein.
Often, polishing pads used in CMP processes are selected based on material properties of the polishing pad and the suitability of those material properties for the desired CMP application. An example of material properties that affects the performance of a polishing pad for a desired CMP application are the tensile modulus and hardness of the material in polishing layer, which is the layer that includes a surface that is in contact with the surface of a substrate during a polishing process. Typically, a material's hardness is proportional to the tensile modulus of the material. Generally, polishing pads formed of comparatively harder materials provide superior local planarization performance when compared to polishing pads formed of softer materials. However, polishing pads formed of harder materials are also associated with increased defectivity (e.g., number of defects per polished surface area) when compared with softer polishing pads. The higher defectivity found when using harder materials in the polishing layer is often attributed to undesirable scratches formed in a substrate surface due to asperities (e.g., high stress contact points) formed in the hard pad material at the polishing surface during a pad conditioning process. Unfortunately, conventional polishing pads also typically soften at the relatively high temperatures (e.g., >40° C.) achieved at the polishing pad surface due to friction, thereby reducing the polishing pad's ability to maintain a desirable hardness over a wide polishing process temperature range, which will typically range in temperature from about 20° C. to about 90° C.
Accordingly, there is a need in the art for polishing pads that maintain their material properties and provide stable performance over a wide temperature range.
SUMMARYEmbodiments of the disclosure include a polishing pad for planarizing a surface of a substrate during a polishing process. The polishing pad includes a base layer, comprising a first material composition, and a polishing layer disposed over the base layer. The polishing layer includes a second material composition that is exposed at a polishing surface of the polishing pad, wherein the polishing surface is configured to contact the surface of the substrate during the polishing process. The second material composition includes a polishing layer material having a hardness that is greater than 50 on a Shore D scale, a yield point strength, a yield point strength strain, a break point strength, and an elongation at break point strain, wherein a magnitude of a difference between the elongation at break point strain and the yield point strength strain is greater than the magnitude of yield point strength strain when measured at room temperature.
Embodiments of the disclosure may further provide a polishing pad for planarizing a surface of a substrate during a polishing process. The polishing pad includes a base layer, comprising a first material composition, and a polishing layer disposed over the base layer. The polishing layer includes a second material composition that is exposed at a polishing surface of the polishing pad, wherein the polishing surface is configured to contact the surface of the substrate during the polishing process. The second material composition comprises a polishing layer material having a hardness that is greater than 50 on a Shore D scale, and a mechanical strain ratio (εB/εY) of greater than 2.
Embodiments of the disclosure may further provide a method of planarizing a surface of a substrate during a polishing process. The method can include conditioning a polishing surface of a polishing pad, delivering a ceria containing polishing slurry composition to the polishing surface of the polishing pad, and urging the surface of the substrate against the polishing surface of the polishing pad while the ceria containing polishing slurry composition is disposed across the polishing surface of the polishing pad. The polishing pad will include a base layer, comprising a first material composition, and a polishing layer disposed over the base layer. The polishing layer includes a second material composition that is exposed at the polishing surface of the polishing pad. The second material composition comprises a polishing layer material having: a hardness that is greater than 50 on a Shore D scale; a yield point strength; a yield point strength strain; a break point strength; and an elongation at break point strain, wherein a magnitude of a difference between the elongation at break point strain and the yield point strength strain is greater than the magnitude of yield point strength strain when measured at room temperature.
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
DETAILED DESCRIPTIONIn the following description, details are set forth by way of example to facilitate an understanding of the disclosed subject matter. It should be apparent to a person of ordinary skill in the field, however, that the disclosed implementations are exemplary and not exhaustive of all possible implementations. Thus, it should be understood that reference to the described examples is not intended to limit the scope of the disclosure. Any alterations and further modifications to the described devices, instruments, methods, and any further application of the principles of the present disclosure are fully contemplated as would normally occur to one skilled in the art to which the disclosure relates. In particular, it is fully contemplated that the features, components, and/or steps described with respect to one implementation may be combined with the features, components, and/or steps described with respect to other implementations of the present disclosure. As used herein, the term “about” may refer to a +/−10% variation from the nominal value. It is to be understood that such a variation can be included in any value provided herein.
Embodiments described herein generally relate to polishing pads, and methods for manufacturing polishing pads, which may be used in a chemical mechanical polishing (CMP) process. In particular, the polishing pads described herein are able improve the polishing performance of a polishing pad during a CMP process by controlling the properties of the polishing layer of a polishing pad and/or the polishing layer and a base layer that supports the polishing layer. Typical properties that can be controlled to improve the polishing performance of a polishing pad, which are generally formed from a polymeric material, include a pad's mechanical properties and/or its physical properties. One aspect of a polishing pad's design that can be controlled to improve the polishing performance of a polishing pad is the mechanical and/or physical properties of a polishing layer material that is disposed at the polishing surface of the polishing pad during a polishing process, which is discussed further below. The physical properties of a portion of a polishing pad that may be of interest will generally include measurable properties of a material, such as, but not limited to, a material's density, melting point, conductivity, coefficient of thermal expansion, and glass transition temperature (Tg). The mechanical properties of a portion of a polishing pad that may be of interest will generally include properties that are exhibited when a load is applied to the material, such as, but not limited to, a tensile modulus (E) (or Young's modulus), storage modulus (E′), loss modulus (E″), yield strength, ultimate tensile strength, elongation at break, KEL, Tan Delta (Tan δ), ductility, and wear resistance.
Undesirably poor local planarization performance is typically associated with conventional polishing pads that have a low hardness, often referred to as softer, elastomeric materials. An example of the effects that a low hardness material containing polishing surface region of a polishing pad has on a surface of a substrate after a polishing process has been performed is schematically illustrated in
Poor local planarization performance of a polishing pad may also result in undesirable recessing of the dielectric layer 802 in the high feature density region 808, e.g., distance “e”, where the upper surfaces of the dielectric layer 802 in the region 808 are recessed from the plane of the field surface 810, otherwise known as erosion. Polishing processes that are used during semiconductor fabrication processes will experience significant metal loss due to poor planarization performance, due to dishing and/or erosion, which can cause undesirable variation in the effective resistance of the metal interconnect features 804, 806 formed therefrom thus affecting device performance and reliability of the formed IC devices.
Another measure of a pad's polishing performance is a pad's local planarization efficiency (PE), which is a measure determined by subtracting the vertical distance from an average position of a top polished surface of a polished substrate to an average low point (or formed depression) in the polishing surface (Dtlp) divided by the distance from the average position of a top polished surface of a polished substrate to the surface of a layer (Dtsl) on which the polishing process is to be stopped (e.g., underlying dielectric layer top surface in a metal CMP process) from one (i.e., PE=1−(Dtlp/Dtsl)). A pad's local planarization efficiency is typically measured over a one square centimeter (cm2) area, and the average low points are typically formed over embedded features, such as vias or trenches formed in the surface of the substrate.
Embodiments described herein will reduce dishing and erosion types of defects over a wide range of feature sizes compared to conventional polishing pad materials, due to the materials, and/or materials and structure, of the polishing pad disclosed herein. In addition, embodiments described herein have more stable or consistent dishing and erosion performance compared to conventional polishing pad materials. In some embodiments described herein provide polishing pads with segmented polishing elements (
Although embodiments described herein are generally related to chemical mechanical polishing (CMP) pads used in semiconductor device manufacturing, the polishing pads and manufacturing methods thereof are also applicable to other polishing processes using at least one of chemically active polishing fluids, chemically inactive polishing fluids and polishing fluids free from abrasive particles. In addition, embodiments described herein, alone or in combination, may be used in at least the following industries: aerospace, ceramics, hard disk drive (HDD), MEMS and Nano-Tech, metalworking, optics and electro-optics manufacturing, and semiconductor device manufacturing, among others.
Polishing System OverviewStill referring to
In some embodiments, as shown in
Each polishing station 124 includes a polishing pad 204 having a polishing surface (e.g., a polishing surface 204A in
Referring to
In other embodiments, the polishing fluid delivery module 135 may comprise a fluid delivery arm 134 to deliver a slurry. Each polishing station 124 comprises a pad conditioning assembly 132. In some embodiments, the fluid delivery arm 134 is configured to deliver a fluid stream (e.g., a fluid 222 in
In some embodiments, the substrates 115, such as a silicon wafer having one or more layers deposited thereon, are loaded into the CMP system 100 via a cassette 114. During processing, the factory interface module 102 extracts the substrate 115 from the cassette 114 to begin processing while a controller 190 coordinates operations of the CMP system 100. The dry robot 110 within the factory interface module 102 then transfers the substrate 115 to the metrology station 117, which in some cases measures a thickness profile of the substrate 115. The dry robot 110 then transfers the substrate 115 to the transfer platforms 116, and the wet robot 108 transfers the substrates through subsequent processing components including the CMP system 100.
The substrate 115 is then transferred by the wet robot 108 to a load cup 122 so that a carrier head 210 can pick-up and transport the substrate 115 to each of the one or more polishing stations 124 to undergo a CMP process according to the polishing parameters selected. Each polishing station includes a polishing pad 204 secured to a rotatable platen 202. Different types of polishing pads 204 may be used at different polishing stations 124 to control the material removal of the substrate 115.
During CMP, the controller 190 controls aspects of the polishing stations 124. In some embodiments, the controller 190 is one or more programmable digital computers executing digital control software. The controller 190 can include a processor 192 situated near the polishing apparatus, e.g., a programmable computer, such as a personal computer. The controller can include a memory 194 and support circuits 196. The controller 190 can, for example, coordinate contact between the substrate 115 and the polishing pad 204 at differing rotational speeds such that a selective removal profile is aligned with indices of residue locations on the substrate 115, such as an asymmetric thickness profile of the substrate 115. Aligning these profiles ensures the thickest part of the substrate 115 has the most material removed and reduces the asymmetry of the substrate 115 during polishing. The controller 190 may include a plurality of separate controllers that are connected via network.
After polishing in at least one of the polishing stations 124, the carrier head 210 (
In some embodiments, the polishing pad 204 is secured to the pad supporting surface 203A of the platen 202 using an adhesive layer 220 (
The carrier head 210, facing the platen 202 and the polishing pad 204 mounted thereon, includes a flexible diaphragm 212 configured to impose different pressures in different regions of the flexible diaphragm 212 against a surface of a substrate 115 that is disposed between the carrier head 210 and the polishing pad 204. The carrier head 210 includes a carrier ring 218 surrounding the substrate 115, which holds the substrate in place. The carrier head 210 rotates about a carrier head axis 216 while the flexible diaphragm 212 urges a to-be-polished surface of the substrate 115, such as a device side of the substrate 115, against a polishing surface 204A of the polishing pad 204. During polishing, a downforce on the carrier ring 218 urges the carrier ring 218 against the polishing surface 204A to improve the polishing process uniformity and prevent the substrate 115 from slipping out from under the carrier head 210.
In some embodiments, the polishing pad 204 rotates about a platen axis 205. The polishing pad 204 has a polishing pad axis 206 that is typically collinear with the platen axis 205. In some embodiments, the polishing pad 204 rotates in the same rotational direction as the rotational direction of the carrier head 210. For example, the polishing pad 204 and carrier head 210 both rotate in a counter-clockwise direction. As shown in
In some embodiments, an endpoint detection (EPD) system 224 detects reflected light that is directed towards the substrate 115 from a light source, through a platen opening 226 and an optically transparent window feature 227 of the polishing pad 204 disposed over the platen opening 226, and then back through these components to a detector (not shown) within the EPD system 224 during processing to detect properties of a layer formed on a surface of the substrate during polishing. The EPD system 224 can allow a thickness and/or residue location measurement, of the substrate 115 to be taken while the polishing assembly 200 is in use. In some embodiments, an eddy current probe is used to measure the thickness of conductive layers formed on a region of a surface of the substrate 115 by the comparison of the relative angle and position of the notch of the substrate 115, or carrier head 210, to the EPD system 224 within the platen 202.
During polishing, a fluid 222 is introduced to the polishing pad 204 through the fluid delivery arm 134 portion of the polishing fluid delivery module 135, which is positioned over the polishing surface 204A of the polishing pad 204. In some embodiments, the fluid 222 is a polishing fluid, a polishing slurry, a cleaning fluid, or a combination thereof. In some embodiments, the polishing fluid may include water based chemistries that include abrasive particles. The fluid 222 may also include a pH adjuster and/or chemically active components, such as an oxidizing agent, to enable CMP of the material surface of the substrate 115 in conjunction with the polishing pad 204. The fluid 222 removes material from the substrate as the carrier head 210 urges the substrate against the polishing pad 204.
As discussed above, the tensile modulus, and/or hardness, of the material disposed at the polishing surface 204A of the polishing pad 204 has a significant effect on the performance of a polishing pad during a CMP process. As discussed briefly above, polishing pads formed of comparatively harder materials provide superior local planarization performance when compared to polishing pads formed of softer materials. However, polishing pads formed of harder materials are also associated with an increased defectivity when compared with softer polishing pads. In general, polishing pads that include harder materials at the polishing surface 204A of a polishing pad will generate a higher number of scratches and other surface defects than a softer pad material. The higher scratch related defectivity found when using harder materials in the polishing layer can often be attributed to the asperities 207 (
It has been found that polishing pads 204 that include a polishing layer material that has desirable properties, such as a high hardness and/or high tensile modulus, and a desirable mechanical strain ratio (εB/εY), can be formed by combining precursor components during a desired polishing pad fabrication process. In some embodiments, as will be discussed further below, the polishing layer material can be formed by use of an additive manufacturing process that allows the material at and within a region near the polishing surface 204A of the polishing layer region 204B to be engineered so that polishing layer material has desired physical and mechanical properties. In some embodiments, the polishing layer region 204B and/or the foundation layer region 204C are both formed by use of an additive manufacturing process in which two or more compositions of precursors are positioned within each layer of a multilayer stack, and, in some cases, at least partially combined to form the polishing layer material. While the ability to and benefits of engineering the properties of different portions of a polishing pad by use of an additive manufacturing process can be easily appreciated, in some cases it may be possible to form a polishing layer material that has desirable properties by use of two or more compositions of precursors that are formed into a useable configuration by use of a conventional casting or molding process, which is currently used to form conventional polishing pads today.
One will note that amount of contact area of similarly configured surfaces is proportional to the tensile modulus material, and thus will decrease as the tensile modulus increases. The surface of the high hardness polymeric material illustrated in
For ease and clarity of discussion purposes, a polishing layer material that exhibits the desirable properties as discussed in relation to
The first class of materials, or brittle polymers C1, are characterized by a high tensile modulus (i.e., slope of the linear portion C1R1 of the stress-strain curve) with very little plastic deformation before the brittle material fractures at the breaking point B1, which coincides with a relatively high breaking strength stress σB1 and low break point strain εB1 at the breaking point B1. Brittle fractures are generally characterized by the formation of jagged features at the fracture surface due to the low amount of plastic deformation found in the material.
The second class of materials, or ductile polymer C2, are characterized by a moderately high tensile modulus, which is seen by slope of the linear portion C2R1 of the stress-strain curve. The ductile polymer C2 materials will include plastic deformation region that includes a yield point Y2 that is followed by a plastic deformation region C2R2 that includes a relatively small plastic deformation strain before the ductile material fractures at the breaking point B2, which coincides with a relatively high breaking strength stress σB2 and moderate break point strain εB2 at the breaking point B2. It is believed that the high hardness polymeric material, which is associated with the material shown in
The third class of materials, or tough polymer C3, are also characterized by a moderately high tensile modulus, which is seen by slope of the linear portion C3R1 of the stress-strain curve. The tough polymer C3 materials will include a large plastic deformation region that includes a yield point Y3 that is followed by a relatively large plastic deformation region and elongation before the tough material fractures at the breaking point B3, which coincides with a relatively moderate breaking strength stress σB3 and large break point strain εB3 at the breaking point B3. As shown in
The forth class of materials, or elastomeric polymer C4 are characterized by a low tensile modulus, which is seen by slope of the linear portion C4R1 of the stress-strain curve. The elastomeric polymer C4 materials will generally not include a yield point and will not contain much of a plastic deformation region, since the elastomeric material will generally have the same stress-strain curve if it is loaded to a point before its breaking point B4 and then unloaded. The material of an elastomeric polymer C4 is also characterized by an increasing stress level from its initial loading until the material fractures at the break point B4, as seen the positive slope in the regions C4R1 and C4R2 of the curve C4 illustrated in
It has been found that rigid polymeric materials, hereafter “rigid materials”, which generally fall within the third class of materials are the preferred material for use as a polishing layer material due to at least their higher relative hardness than conventional polishing pads, their improved dishing and planarization performance, and desirable defectivity results after performing one or more pad conditioning processes. Rigid materials that include a yield point that is followed by a significant elongation until the material breaks has been found to provide these desirable polishing pad performance results.
As will be discussed further below, the pre-polymer compositions that are used to form the “rigid material” may include a mixture of one or more of functional polymers, functional oligomers, functional monomers, functional cross-linkers, reactive diluents, additives, and photoinitiators. Examples of suitable functional polymers which may be used to form one or more of the at least two pre-polymer compositions that are used to form the rigid material can include multifunctional acrylate including di, tri, tetra, and higher functionality acrylates, such as 1,3,5-triacryloylhexahydro-1,3,5-triazine or trimethylolpropane triacrylate, dipropylene glycol diacrylate or dimethacrylate. Other examples of pre-polymer compositions are discussed further below.
It has been additionally found that rigid materials that exhibit a desirable mechanical strain ratio (εB/εY) are able to achieve an improved dishing and planarization performance, and a desirable substrate defectivity result. Due to the ability of the rigid material to have a relatively high level of hardness (or high tensile modulus) and yet plastically deform a significant amount before break is believed to be a significant factor in the improved polishing pad performance results. As discussed above, the ability of the rigid material to plastically deform during the pad conditioning process will cause the rigid material at the polishing surface 204A to be smoothed versus creating brittle fracture regions for similarly hard polymeric materials during the pad conditioning process. One measure used to characterize a rigid material that is able to achieve the desirable polishing process performance is the mechanical strain ratio (εB/εY), which is a ratio of the measured strain at the breaking point minus the measure strain at the yield point divided by the measured strain at the yield point. For example, the mechanical strain ratios (εB/εY) for the material illustrated by curves C5, C6 and C7 in
It has been found that hard materials that yield and have a long elongation at break are able to achieve desirable dishing, planarization, and defectivity performance when used in a standard CMP polishing process. In some embodiments, the rigid material includes a mechanical strain ratio (εB/εY) that is greater than 1.0, such as greater than 2.0, greater than 2.2, greater than 2.5, greater than 3.0, greater than 5.0, greater than 8.0, greater than 10, greater than 20 or even greater than 25. In some embodiments, the rigid material also has an elongation at break of at least 20%, such as greater than 40%, or even greater than 100%. In some embodiments, the rigid material also includes a hardness of at least 50 on the Shore D scale, a hardness of at least 60 on the Shore D scale, a hardness of at least 65 on the Shore D scale, a hardness of at least 68 on the Shore D scale, or even a hardness greater than 70 on the Shore D scale. In some embodiments, the rigid material includes a hardness in a range from 60 to 80 on the Shore D scale, such as a range from 65 to 80 on the Shore D scale, or even in a range from 68 to 78 on the Shore D scale. In some embodiments, the rigid material also has a tensile modulus of at least 1000 megapascals (MPa), such as greater than 1200 MPa, or even greater than 2000 MPa, or even from 1000 to 2000 MPa. In some embodiments, the rigid material also has a yield strength of at least 30 megapascals (MPa), such as greater than 40 megapascals (MPa), or even greater than 60 megapascals (MPa), or even from 30 to 60 MPa. In some embodiments, the rigid material also has a glass transition temperature (Tg) of at least 40° C., such as greater than 50° C., or even greater than 60° C.
In some example, the rigid material has a hardness that is between 62 and 80 on the Shore D scale, a tensile modulus of between 1000 and 2000 MPa and a mechanical strain ratio (εB/εY) that is at least greater than 2. In another example, the rigid material has a hardness that is between 65 and 78 on the Shore D scale, a tensile modulus of between 1000 and 2000 MPa and a mechanical strain ratio (εB/εY) that is at least greater than 2.
It has been found that rigid material formulations that include a hardness that is between 60 and 80 on the Shore D scale, a tensile modulus of between 1000 and 2000 MPa and a mechanical strain ratio (εB/εY) that is at least greater than 2 are able to achieve a reduced defectivity and improved planarization efficiency over conventional formulations after the same pad conditioning process had been performed on the different formulations. More conventional formulations, such as the brittle polymers C1 and ductile polymers C2 formulations illustrated in
Referring back to
Comparing the SEM images of the surfaces 551A, 552A, and 553A of the conventional sample 551, the first sample 552 and the second sample 553, respectively, in
As illustrated in
It has been found that the rigid material formulations described herein are beneficially configured to achieve contact ratios that are at least greater than 0.8%, such as greater than 1.0%, or greater than 2.0%, or greater than 2.5%, or greater than 4.0%, or even greater than 5.0% when measured at a measurement depth (DM) of about 4 μm after performing a standard pad conditioning process as described herein. The increased contact ratios over convention pad materials will provide a significant benefit relating to the planarization efficiency and defectivity of a polished substrate, along with an increase in polishing rate of a substrate during various polishing processes, such as ceria based polishing processes.
Formulation and Material ExamplesAs briefly discussed above, in some embodiments, a polishing layer region 204B that includes the rigid material is formed from a mixture of two or more pre-polymer compositions that are at least partially mixed and cured to cause at least partial polymerization, e.g., cross-linking, of the pre-polymer composition(s) to form a continuous polymer phase. In some embodiments, by use of an additive manufacturing process, which is described further below, the formed continuous polymer phase forms the structural elements of the polishing pad 204, such as the polishing features 204G of the polishing layer region 204B. Pre-polymer compositions of the present disclosure may include a mixture of one or more of functional polymers, functional oligomers, functional monomers, functional cross-linkers, reactive diluents, additives, and photoinitiators.
Examples of suitable functional polymers which may be used to form one or both of the at least two pre-polymer compositions include multifunctional acrylates including di, tri, tetra, and higher functionality acrylates, such as 1,3,5-triacryloylhexahydro-1,3,5-triazine or trimethylolpropane triacrylate, dipropylene glycol diacrylate or dimethacrylate.
Examples of suitable functional oligomers which may be used to form one or both of the at least two pre-polymer compositions include monofunctional and multifunctional oligomers, acrylate oligomers, such as aliphatic urethane acrylate oligomers, aliphatic hexafunctional urethane acrylate oligomers, diacrylate, aliphatic hexafunctional acrylate oligomers, multifunctional urethane acrylate oligomers, aliphatic urethane diacrylate oligomers, aliphatic urethane acrylate oligomers, aliphatic polyester urethane diacrylate blends with aliphatic diacrylate oligomers, or combinations thereof, for example bisphenol-A ethoxylate diacrylate or polybutadiene diacrylate, tetrafunctional acrylated polyester oligomers, aliphatic polyester based urethane diacrylate oligomers and aliphatic polyester based acrylates and diacrylates.
Examples of suitable monomers which may be used to from one or both of the at least two pre-polymer compositions include both mono-functional monomers and multifunctional monomers. Suitable mono-functional monomers include tetrahydrofurfuryl acrylate (e.g. SR285 from Sartomer®), tetrahydrofurfuryl methacrylate, vinyl caprolactam, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, 2-phenoxyethyl methacrylate, 2-(2-ethoxyethoxy)ethyl acrylate, isooctyl acrylate, isodecyl acrylate, isodecyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, cyclic trimethylolpropane formal acrylate, 2-[[(Butylamino) carbonyl]oxy]ethyl acrylate (e.g. Genomer 1122 from RAHN USA Corporation), cycloaliphatic acrylate (e.g. SR217 from Sartomer®), 3,3,5-trimethylcyclohexyl acrylate, or mono-functional methoxylated PEG (350) acrylate. Suitable multifunctional monomers include diacrylates or dimethacrylates of diols and polyether diols, such as propoxylated neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, 1,3-butylene glycol diacrylate, 1,3-butylene glycol dimethacrylate 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, alkoxylated aliphatic diacrylate (e.g., SR9209A from Sartomer®), diethylene glycol diacrylate, diethylene glycol dimethacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, triethylene glycol dimethacrylate, alkoxylated hexanediol diacrylates, or combinations thereof, for example SR508, SR562, SR563, SR564 from Sartomer®.
Typically, the reactive diluents used to form one or more of the pre-polymer compositions are least monofunctional, and undergo polymerization when exposed to free radicals, Lewis acids, and/or electromagnetic radiation. Examples of suitable reactive diluents include monoacrylate, 2-ethylhexyl acrylate, octyldecyl acrylate, cyclic trimethylolpropane formal acrylate, caprolactone acrylate, isobornyl acrylate (IBOA), or alkoxylated lauryl methacrylate. In some examples, reactive diluents may include Genocure series products, such as PBZ, or Genomer series products, such as Genomer 5142, each manufactured by Rahn AG of Zurich, Switzerland.
Examples of suitable additives include surface modifiers such as surfactants to control surface tension. Some example additives may include ethoxylated polydimethylsiloxanes, such as BYK series products, such as BYK-307, manufactured by BYK-Chemie GmbH of Wesel, Germany.
Examples of suitable photoinitiators used to form one or more of the at least two different pre-polymer compositions include polymeric photoinitiators and/or oligomer photoinitiators, such as benzoin ethers, benzyl ketals, acetyl phenones, alkyl phenones, phosphine oxides, benzophenone compounds and thioxanthone compounds that include an amine synergist, or combinations thereof. In some examples, photoinitiators may include Irgacure® series products, such as Irgacure® 819, manufactured by BASF of Ludwigshafen, Germany.
Examples of polishing pad materials formed of the pre-polymer compositions described above typically include at least one of oligomeric and, or, polymeric segments, compounds, or materials selected from the group consisting of: polyamides, polycarbonates, polyesters, polyether ketones, polyethers, polyoxymethylenes, polyether sulfone, polyetherimides, polyimides, polyolefins, polysiloxanes, polysulfones, polyphenylenes, polyphenylene sulfides, polyurethanes, polystyrene, polyacrylonitriles, polyacrylates, polymethylmethacrylates, polyurethane acrylates, polyester acrylates, polyether acrylates, epoxy acrylates, polycarbonates, polyesters, melamines, polysulfones, polyvinyl materials, acrylonitrile butadiene styrene (ABS), halogenated polymers, block copolymers, and random copolymers thereof, and combinations thereof.
Rigid Material ExamplesA rigid material that can be used to form a desirable polishing layer is formed from at least two different materials that are formed from the pre-polymer compositions that contain “resin precursor components” that include, but are not restricted to functional polymers, functional oligomers, monomers, reactive diluents, flow additives, curing agents, photoinitiators, and cure synergists.
In some embodiments, the rigid material is formed from a composition that includes an aromatic monofunctional acrylate, a low viscosity aliphatic trifunctional monomer, a trifunctional aliphatic acrylate, and a monofunctional aliphatic acrylamide. In one example, the rigid material is formed from a pre-polymer composition that includes (by weight ratio) 34.2% of a IBXA diluted Oligomer, 8% of DEAA, 3.8% of SR351H, 21.1% of TMCHA, 30.9% of IBXA, and 2% of Omnirad 819. In this example, the rigid material had a mechanical strain ratio (εB/εY) of about 2, a hardness of about 75 on the Shore D scale, a tensile modulus of about 1500 megapascals (MPa), a yield strength of at least 30 megapascals (MPa), and an elongation at break of about 8%.
In a second example, the resin precursor components used to form the rigid material may include, an oligomer, such as tri functional urethane, one or more monomers, such as difunctional polyether acrylate, a reactive diluent, such as monofunctional urethane acrylate, flow additives, curing agents, and photoinitiators. In this example, the rigid material had a mechanical strain ratio (εB/εY) of about 8, a hardness of about 68 on the Shore D scale, a tensile modulus of about 1200 megapascals (MPa), a yield strength of at least 26 megapascals (MPa), and an elongation at break of about 60%.
In a third example, the resin precursor components used to form the rigid material may include, an oligomer, such as difunctional polyester acrylate, one or more monomers, such as difunctional epoxy acrylate, a reactive diluent, such as monofunctional methacrylate, flow additives, curing agents, and photoinitiators. In this example, the rigid material had a mechanical strain ratio (εB/εY) of about 10, a hardness of about 60 on the Shore D scale, a tensile modulus of about 1000 megapascals (MPa), a yield strength of at least 22 megapascals (MPa), and an elongation at break of about 80%.
Pore Forming FeaturesIn some embodiments of the polishing pad 204, pore-features are formed into a region at and/or just below the polishing surface 204A of the polishing pad 204. The pore-features can be formed by use of a sacrificial material precursor that is deposited in desired locations within the layers used to form the polishing layer of the polishing pad by use of an additive manufacturing process, which is described below. The sacrificial material precursor can include water-soluble materials, such as, glycols (e.g., polyethylene glycols), glycol-ethers, and amines. Examples of suitable sacrificial material precursors which may be used to form the pore forming features described herein include ethylene glycol, butanediol, dimer diol, propylene glycol-(1,2) and propylene glycol-(1,3), octane-1,8-diol, neopentyl glycol, cyclohexane dimethanol (1,4-bis-hydroxymethylcyclohexane), 2-methyl-1,3-propane diol, glycerine, trimethylolpropane, hexanediol-(1,6), hexanetriol-(1,2,6) butane triol-(1,2,4), trimethylolethane, pentaerythritol, quinitol, mannitol and sorbitol, methylglycoside, also diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols, dibutylene glycol, polybutylene glycols, ethylene glycol, ethylene glycol monobutyl ether (EGMBE), diethylene glycol monoethyl ether, ethanolamine, diethanolamine (DEA), triethanolamine (TEA), and combinations thereof.
In some embodiments, the sacrificial material precursor includes a water soluble polymer, such as 1-vinyl-2-pyrrolidone, vinylimidazole, polyethylene glycol diacrylate, acrylic acid, sodium styrenesulfonate, Hitenol BC10®, Maxemul 6106®, hydroxyethyl acrylate and [2-(methacryloyloxy)ethyltrimethylammonium chloride, 3-allyloxy-2-hydroxy-1-propanesulfonic acid sodium, sodium 4-vinylbenzenesulfonate, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide, 2-acrylamido-2-methyl-1-propanesulfonic acid, vinylphosphonic acid, allyltriphenylphosphonium chloride, (vinylbenzyl)trimethylammonium chloride, E-SPERSE RS-1618, E-SPERSE RS-1596, methoxy polyethylene glycol monoacrylate, methoxy polyethylene glycol diacrylate, methoxy polyethylene glycol triacrylate, or combinations thereof.
Additive Manufacturing Process and SystemHere, each of dispense heads 604, 606 features an array of droplet ejecting nozzles 616 configured to eject droplets 630, 632 of the respective pre-polymer composition 612 and sacrificial material composition 614 delivered to the dispense head reservoirs. Here, the droplets 630, 632 are ejected towards the manufacturing support 602 and thus onto the manufacturing support 602 or onto a previously formed print layer 618 disposed on the manufacturing support 602. Typically, each of dispense heads 604, 606 is configured to fire (control the ejection of) droplets 630, 632 from each of the nozzles 616 in a respective geometric array or pattern independently of the firing of other nozzles 616 thereof. Herein, the nozzles 616 are independently fired according to a droplet dispense pattern for a print layer to be formed, such as the print layer 624, as the dispense heads 604, 606 move relative to the manufacturing support 602. Once dispensed, the droplets 630 of the pre-polymer composition 612 and/or the droplets 632 of the sacrificial material composition 614 are at least partially cured by exposure to electromagnetic radiation, e.g., UV radiation 626, provided by the curing source 608, e.g., an electromagnetic radiation source, such as a UV radiation source to form a print layer, such as the partially formed print layer 624.
Here, the additive manufacturing system 600 shown in
Typically, the memory 635 is in the form of a computer-readable storage medium containing instructions (e.g., non-volatile memory), which when executed by the CPU 634, facilitates the operation of the manufacturing system 600. The instructions in the memory 635 are in the form of a program product such as a program that implements the methods of the present disclosure.
The program code may conform to any one of a number of different programming languages. In one example, the disclosure may be implemented as a program product stored on computer-readable storage media for use with a computer system. The program(s) of the program product define functions of the embodiments (including the methods described herein).
Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are embodiments of the present disclosure. In some embodiments, the methods set forth herein, or portions thereof, are performed by one or more application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other types of hardware implementations. In some other embodiments, the polishing pad manufacturing methods set forth herein are performed by a combination of software routines, ASIC(s), FPGAs and, or, other types of hardware implementations.
Here, the system controller 610 directs the motion of the manufacturing support 602, the motion of the dispense heads 604 and 606, the firing of the nozzles 616 to eject droplets of pre-polymer compositions therefrom, and the degree and timing of the curing of the dispensed droplets provided by the UV radiation source 608. In some embodiments, the instructions used by the system controller to direct the operation of the manufacturing system 600 include droplet dispense patterns for each of the print layers to be formed. In some embodiments, the droplet dispense patterns are collectively stored in the memory 635 as CAD-compatible digital printing instructions.
In some embodiments, dispensed droplets of the pre-polymer compositions, such as the dispensed droplets 630 of the pre-polymer composition 612, are exposed to electromagnetic radiation to physically fix the droplet before it spreads to an equilibrium size such as set forth in the description of
Herein, at least partially curing a dispensed droplet causes at least partial polymerization, e.g., cross-linking, of the pre-polymer composition(s) within the droplets and with adjacently disposed droplets of the same or different pre-polymer compositions to form a continuous polymer phase. In some embodiments, the pre-polymer compositions are dispensed and at least partially cured to form a well about a desired pore before a sacrificial material composition is dispensed thereinto.
At activity 710, the method 700 includes dispensing droplets of a pre-polymer composition onto a surface of a previously formed print layer according to a predetermined droplet dispense pattern. In this configuration, activity 710 will include a process of dispensing droplets of a pre-polymer composition and dispensing droplets of a sacrificial material composition onto a surface of a previously formed print layer according to a predetermined droplet dispense pattern to form a layer within the polishing pad 204.
At activity 720, the method 700 includes at least partially curing the dispensed droplets of the pre-polymer composition to form a print layer that includes the rigid material. In some embodiments, the rigid material layer may also include a plurality of pore-features that include the sacrificial material composition.
In some embodiments, the method 700 further includes sequential repetitions of activities 710 and 720 to form a plurality of print layers stacked in a Z-direction, i.e., a direction orthogonal to the surface of the manufacturing support or a previously formed print layer disposed thereon. The predetermined droplet dispense pattern used to form each print layer may be the same or different as a predetermined droplet dispense pattern used to form a previous print layer disposed there below.
In some embodiments of the method 700, the plurality of print layers include a polishing layer having a plurality of pores, or pore-features, formed therein. In some embodiments, the plurality of print layers include a polishing layer having a plurality of pore-forming features formed therein in which the plurality of pore-forming features include the sacrificial material composition.
The preceding description is provided to enable any person skilled in the art to practice the various embodiments described herein. The examples discussed herein are not limiting of the scope, applicability, or embodiments set forth in the claims. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments. For example, changes are made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method that is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.
The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. Further, the various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrated circuit (ASIC), or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims
1. A polishing pad for planarizing a surface of a substrate during a polishing process, comprising:
- a base layer, comprising a first material composition; and
- a polishing layer disposed over the base layer, wherein the polishing layer comprises a second material composition that is exposed at a polishing surface of the polishing pad, the polishing surface is configured to contact the surface of the substrate during the polishing process, the second material composition comprises a polishing layer material having: a hardness that is greater than 50 on a Shore D scale; a yield point strength; a yield point strength strain; a break point strength; and an elongation at break point strain, wherein a magnitude of a difference between the elongation at break point strain and the yield point strength strain is greater than the magnitude of yield point strength strain when measured at room temperature.
2. The polishing pad of claim 1, wherein the break point strength is less than the yield point strength.
3. The polishing pad of claim 2, wherein the hardness of the second material composition is greater than 60 on a Shore D scale.
4. The polishing pad of claim 1, wherein the hardness of the second material composition is in a range from 65 to 78 on a Shore D scale.
5. The polishing pad of claim 1, wherein the magnitude of the difference between the elongation at break point strain and the yield point strength strain is at least 2 times greater than the magnitude of yield point strength strain.
6. The polishing pad of claim 5, wherein the polishing layer material further includes:
- a glass transition temperature (Tg) of between about 60-80 C;
- a tensile Modulus of about 100-2,000 MPa at 40 C; and
- an E′ ratio at 30 C-90 C of between about 1 and 5.
7. The polishing pad of claim 1, wherein the polishing surface of the polishing layer material comprises:
- a contact ratio of at least 0.8% at a measurement depth (DM) of 4 μm after performing a standard pad conditioning process.
8. The polishing pad of claim 1, wherein the polishing surface of the polishing layer material comprises:
- a contact ratio of at least 2% at a measurement depth (DM) of 4 μm after performing a standard pad conditioning process.
9. A polishing pad for planarizing a surface of a substrate during a polishing process, comprising:
- a base layer, comprising a first material composition; and
- a polishing layer disposed over the base layer, wherein the polishing layer comprises a second material composition that is exposed at a polishing surface of the polishing pad, the polishing surface is configured to contact the surface of the substrate during the polishing process, and the second material composition comprises a polishing layer material having: a hardness that is greater than 50 on a Shore D scale; and a mechanical strain ratio (εB/εY) of greater than 2.
10. The polishing pad of claim 9, wherein the polishing layer material has a hardness that is greater than 65 on the Shore D scale.
11. The polishing pad of claim 9, wherein
- the hardness is between 65 and 78 on the Shore D scale, and
- the polishing layer material has a tensile modulus of between 1000 and 2000 MPa and an elongation at break of greater than about 60%.
12. The polishing pad of claim 9, wherein resin precursor components used to form the polishing layer material comprise an oligomer, one or more monomers, and a reactive diluent.
13. The polishing pad of claim 12, wherein
- the oligomer comprises a tri-functional urethane;
- the one or more monomers comprise a difunctional polyether acrylate; and
- the reactive diluent comprises a monofunctional urethane acrylate.
14. The polishing pad of claim 12, wherein
- the oligomer comprises a difunctional polyester acrylate;
- the one or more monomers comprise a difunctional epoxy acrylate; and
- the reactive diluent comprises a monofunctional methacrylate.
15. The polishing pad of claim 12, wherein the polishing layer material comprises an aromatic monofunctional acrylate, a low viscosity aliphatic trifunctional monomer, a trifunctional aliphatic acrylate, and a monofunctional aliphatic acrylamide.
16. The polishing pad of claim 15, wherein the polishing surface of the polishing layer comprises:
- a contact ratio of at least 0.8% at a measurement depth (DM) of 4 μm after performing a standard pad conditioning process.
17. The polishing pad of claim 10, wherein the second material composition has a break point strength that is less than its yield point strength.
18. A method of planarizing a surface of a substrate during a polishing process, comprising:
- conditioning a polishing surface of a polishing pad;
- delivering a ceria containing polishing slurry composition to the polishing surface of the polishing pad; and
- urging the surface of the substrate against the polishing surface of the polishing pad while the ceria containing polishing slurry composition is disposed across the polishing surface of the polishing pad,
- wherein the polishing pad comprises: a base layer, comprising a first material composition; and a polishing layer disposed over the base layer, wherein the polishing layer comprises a second material composition that is exposed at the polishing surface of the polishing pad, and the second material composition comprises a polishing layer material having: a hardness that is greater than 50 on a Shore D scale; a yield point strength; a yield point strength strain; a break point strength; and an elongation at break point strain, wherein a magnitude of a difference between the elongation at break point strain and the yield point strength strain is greater than the magnitude of yield point strength strain when measured at room temperature.
19. The method of claim 18, wherein the second material composition further comprises:
- a hardness that is greater than 68 on a Shore D scale; and
- a mechanical strain ratio (εB/εY) of greater than 2.
20. The method of claim 19, wherein the polishing surface of the polishing layer comprises:
- a contact ratio of at least 0.8% at a measurement depth (DM) of 4 μm after conditioning the polishing surface of the polishing pad using a standard pad conditioning process.
Type: Application
Filed: Apr 24, 2023
Publication Date: Nov 16, 2023
Inventors: Shiyan Akalanka Jayanath WEWALA GONNAGAHADENIYAGE (Sunnyvale, CA), Ashwin CHOCKALINGAM (Santa Clara, CA)
Application Number: 18/138,502