Pad for chemical planarization

Abstract

A pad for performing non-abrasive chemical planarization of a substrate comprises a polymer layer configured to contact the substrate during non-abrasive chemical planarization. The polymer layer comprises multiple reactive units covalently bonded within the polymer chain. Each reactive unit comprises a functional group containing one or more complexing agents or hydrolyzing agents for performing non-abrasive chemical planarization.

Description

【Technical Field】 【0001】 The present invention relates to a pad for performing non-abrasive chemical planarization of a substrate. 【Background Art】 【0002】 Chemical mechanical planarization (CMP) is commonly used in integrated circuit manufacturing processes to planarize surfaces such as the surface of a semiconductor substrate by removing material using a combination of chemical and mechanical forces. A typical CMP process involves using an abrasive and a chemical slurry that can be corrosive to the material being removed, in combination with a polishing pad. The substrate and the polishing pad are pressed against each other and rotate relative to each other about non-concentric axes of rotation. The combination of force and slurry removes areas of the substrate having a higher topology compared to areas having a lower topology, thereby planarizing the surface. 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0003】 This summary is provided to introduce, in a simplified form, a selection of concepts that are further described in the detailed description below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Further, the claimed subject matter is not limited to embodiments that solve any or all disadvantages noted in any part of this disclosure. 【Means for Solving the Problems】 【0004】 Examples related to a pad for performing non-abrasive chemical planarization of a substrate are disclosed. One example provides a pad that includes a polymer layer configured to contact the substrate during non-abrasive chemical planarization, the polymer layer including a plurality of reactive units covalently bonded within the polymer chain, each reactive unit including a functional group that includes one or more of a complexing agent or a hydrolyzing agent for performing non-abrasive chemical planarization. [Brief explanation of the drawing] 【0005】 [Figure 1] This is a block diagram of an exemplary chemical planarization system. [Figure 2A] This is a schematic diagram of an exemplary pad for performing chemical planarization. [Figure 2B] Figure 2A shows an exemplary pad, illustrating the contact between the topologically high portion of the substrate and the upper layer of the pad. [Figure 3] This is a schematic diagram of another exemplary pad for performing chemical planarization. [Figure 4] This is a schematic diagram of another exemplary pad, including a textured substrate-facing surface. [Figure 5A] This is a schematic diagram illustrating an example of incorporating functional groups into a polymer. [Figure 5B] This is a schematic diagram illustrating an example of incorporating functional groups into a polymer. [Figure 6] This figure shows examples of monomers that can be used to form pads for chemical planarization. [Figure 7A] This flowchart illustrates an exemplary method for forming a pad for chemical planarization. [Figure 7B] This is a flowchart illustrating an exemplary method for forming a pad for chemical planarization. [Figure 8] This is a schematic diagram of another exemplary pad for performing chemical planarization. [Modes for carrying out the invention] 【0006】 While current CMP methods are used in a wide variety of device manufacturing situations, they also have various drawbacks. For example, current CMP processes are relatively dirty compared to other manufacturing processes, at least in part, due to the use of conditioning chemicals, as well as polishing slurries and pads that mechanically polish the material during planarization. Defects generated by CMP can cause significant yield losses for the fab. Defects and scratches generated during CMP can largely be attributable to mechanical components in the process, such as abrasives in the slurry, pad force on the substrate, pad conditioning, and the tribological aspects of the process. Furthermore, the slurry contains abrasives that can scratch the device layer, thereby creating pits and leaving residues that can become killer defects. In addition, pad debris is generated during polishing and pad conditioning. Such pad debris can generate particles and aggregates that contaminate the substrate being processed. Also, the pad force on the wafer can cause pad deformation. This can result in shear stress at the interface due to close contact with the substrate and relative motion between the substrate and the pad. Furthermore, the CMP process can be unpredictable, and therefore, a trial-and-error approach may prevail rather than an analytical one. Additionally, handling, delivery, and stabilization of the slurry can present challenges to the manufacturing equipment due to solid content, potentially increasing equipment maintenance costs. Consequently, conventional CMP processes may require redundancy for deposition and excessive polishing, which can lead to wasted resources, increased costs, and decreased productivity. 【0007】 Accordingly, examples of pads for performing chemical planarization without the dirty and defect-prone mechanical processes used in conventional CMP methods are disclosed herein. Briefly, the disclosed examples utilize non-abrasive planarization chemistry in a pad instead of an abrasive slurry. The term "non-abrasive" indicates a planarization chemistry that does not use mechanical abrasive solid components to remove the substrate material by abrasion. The disclosed pad comprises at least one polymer layer configured to contact a substrate during non-abrasive chemical planarization. The polymer layer comprises a plurality of reactive units covalently bonded within the polymer chain. Each reactive unit comprises a functional group comprising one or more complexing agents or hydrolyzing agents for performing non-abrasive chemical planarization. 【0008】 Using the disclosed pad, the substrate can be controlled so that topologically high features of the substrate contact the pad, while topologically low features do not. The planarization chemical action is exposed to the portion of the substrate in contact with the pad, thereby selectively removing material from those portions of the substrate. In this way, the topology of the substrate surface can be made smoother by applying relatively light pressure to the substrate without using abrasives. This helps to avoid scratches or other damage to the device layer, thereby helping to avoid defects and potentially improve yield compared to conventional CMP processes. 【0009】 Before describing disclosed examples of non-abrasive planarizing pads, Figure 1 shows a schematic diagram of an exemplary chemical planarizing system 100 according to this disclosure. System 100 includes a platen 102 supporting a pad 104. System 100 further includes a substrate holder 106 configured to hold a substrate 108 against the surface of the pad 104, and a planarizing solution introduction system 110 for introducing a planarizing solution 112 onto the pad 104. System 100 may further include a pad rinsing system 114 configured to rinse off any contaminating material from the pad 104, such as composite material removed from the surface of the substrate 108. The pad rinsing system 114 may also be used to clean the pad between different planarizing solution chemistrys, as described below. Other components (not shown) that can be incorporated into System 100 include, but are not limited to, a used solution recovery system, a material recirculation system (e.g., for recirculating the planarizing solution within a closed-loop process), and a chemical species stripping system. 【0010】 In conventional CMP processes, a substrate holder presses the substrate against a polishing pad supported on a platen, and the pad and substrate rotate relative to each other in a non-concentric pattern. Such conventional processes use relatively high rotational speeds, such as 40–100 rpm. Furthermore, the substrate is pressed against the pad with relatively high pressure, such as in the range of 1–4 pounds / square inch. In contrast, the disclosed example may use lighter pressures, including, but not limited to, pressures in the range of 0.25–0.75 pounds / square inch. Lighter pressures can avoid distortion of the pad shape and can reduce shear stress compared to conventional CMP processes. Similarly, since rotational motion is not used for polishing, slower rotational speeds may be used in the disclosed example than in conventional CMP processes. Instead, the rotation of the platen 102 helps distribute the planarizing fluid across the pad 104. Any suitable rotational speed can be used. Examples include speeds in the range of 0–60 rpm. More specific examples include speeds of 5–30 rpm. As described above, in the examples herein, rotational motion is not used to polish the material from the substrate, so the rotational speed may be lower than the speed at which the platen rotates in conventional CMP processes. It will be understood that many different configurations and designs are possible for various platform types (rotary, linear or belt, vertical, roller, hollow fiber). 【0011】 The planarization solution may contain chemical components for hydrolyzing the substrate material (e.g., by oxidation and dissolution). The planarization solution may be configured to remove any suitable material. As an example, polysilicon may be removed via a planarization solution containing poly(diallyldimethylammonium chloride) (PDADMAC) in deionized water. In some such examples, the PDADMAC solution may be mixed with oxalic acid and / or hydrogen peroxide and may further contain a suitable acid or alkali agent (e.g., nitric acid or potassium hydroxide) to adjust the pH. Other reagents may also be used to planarize polysilicon, including but not limited to poly(dimethylamine-co-epichlorohydrin-co-ethylenediamine), poly(allylamine), and poly(ethyleneimine) (PEI). In other examples, one or more metals such as copper, molybdenum, ruthenium, rhenium, rhodium, and cobalt can be removed using a planarization solution containing hydrogen peroxide and guanidine carbonate, together with a pH adjuster to achieve the desired solution pH. As another example, ammonium persulfate can be used to remove suitable metals (e.g., cobalt) with the help of a pH adjuster to achieve the desired solution pH. Other examples of suitable hydrolysants include, but are not limited to, nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, ammonium hydroxide, sodium hydroxide, and potassium hydroxide. 【0012】 In some examples, the planarization solution may contain additional components. For example, the planarization solution may contain a complexing / chelating agent for transporting the material removed from the substrate after hydrolysis. Suitable chelating agents include, but are not limited to, ethylenediaminetetraacetic acid (EDTA), sulfosalicylic acid, naphthol (PAN), dithizone, organophosphate esters, polyethylene glycol, amines, and thioxins. Furthermore, in some examples, the planarization solution may contain passivating agents and / or corrosion inhibitors. Examples include, but are not limited to, benzatriaazole (BTA), ammonium dodecyl sulfate (ADS), tolyltriazole (TTA), thiols (e.g., PTAT (5-(phenyl)-4H-1,2-4-triazole-3-thiol)), thiodiazoles, carboxylic acids, benzoic acid, and ammonium benzoate. Other examples of materials that may be included in the planarization solution include, but are not limited to, surfactants, surface modifiers other than passivators and / or corrosion inhibitors, catalysts, thermally activated chemicals, photoactivated chemicals, chemical species tracers, additives, and stabilizers. 【0013】 Inhibitors such as BTA can help achieve planarization by suppressing the removal rate in the low-topographic regions of the wafer. However, BTA and other corrosion inhibitors can be hazardous and may cause environmental problems during disposal. Furthermore, BTA can interact with other materials (e.g., nano-abrasives) in conventional CMP processes, potentially creating residues on the wafer that are difficult to remove, thus complicating the process of cleaning the wafer after polishing. As will be described in more detail below, functionalized pads can selectively polish high-topographic regions without the use of additional inhibitors. This results in a cleaner process and eliminates the need for additional post-planarization cleaning steps. 【0014】 In some examples, hydrolyzing agents and complexing agents are bonded to the functionalized polymer of the pad, as described in more detail below. In some such examples, the planarization solution distributed on the pad may contain deionized water, and chemical planarization may be performed by the functionalized polymer. In other such examples, the planarization solution may contain additional components other than deionized water. 【0015】 Figures 2A and 2B show schematic diagrams of an exemplary pad 200 suitable for use as pad 104. Pad 200 comprises a first polymer layer 202 and a second polymer layer 204. The first polymer layer 202 is configured to contact the substrate 206 during non-abrasive chemical planarization. The second polymer layer 204 is located on the side of the first polymer layer 202 opposite to the side of the first polymer layer 202 that contacts the substrate. Such a double-layer structure can be used to carry out multi-step material removal and separation processes, which, depending on the chemical formulation of the pad and the composition of the planarization solution, include one or more chemical steps (hydrolysis (and potential dissolution), oxidation, hydroxylation, ionization, and radical formation of the chemical species to be removed) and chemical complexation of the chemical species to be removed. Furthermore, the first polymer layer 202 and the second polymer layer 204 can be configured to have other functions. For example, the second polymer layer can be configured to be compressible. Therefore, when the first polymer layer 202 comes into contact with the substrate 206 during the chemical planarization process, the second polymer layer 204 can be compressed to avoid applying undesirable pressure to the substrate 206. In some such examples, both hydrolysis and complexation are configured to occur in the same layer (e.g., the first polymer layer 202). Furthermore, in some examples, the first polymer layer may include a textured surface, as will be described in more detail below. 【0016】 The first and second layers may be joined to each other by any suitable method. In some examples, the first and second layers are joined by an adhesive. In other examples, one of the first or second layers is insert-molded into the other of the first or second layer. In yet another example, one or both of the first or second layers can be additively manufactured. In yet another example, the first and second layers may be formed in the same molding or casting process, but the composition of the material being molded or cast is changed during injection or molding. In such an example, this constitutes an asymmetric medium, as the top and bottom layers have different properties. Such an asymmetric medium may, in some examples, involve a gradual and systematic variation in properties, or a sharp transition at the interface of the two layers. This allows for control over the compressibility and other mechanical properties of the first polymer layer 202 and / or the second polymer layer 204. In other examples, the two layers are integrated to seemingly constitute a composite pad. Furthermore, the pad 200 may be bonded or otherwise attached to an additional sub-layer, such as a woven matrix or a flexible polymer sheet (e.g., a sub-pad of the type currently used in conventional CMP polishing pads). 【0017】 In some examples, such asymmetric structures can be formed using polymer phase inversion or phase separation. In other examples, vapor-induced phase separation (air casting) can be used. In yet another example, liquid-induced phase separation (immersion casting) can be used by dissolving the polymer in a solvent at room temperature and immersing it in a liquid non-solvent to induce phase separation. This enables a variety of forms, including asymmetric membranes. Methods for forming asymmetric structures (e.g., multilayer porous matrices) include manipulating phase separation conditions during monolayer casting, casting a small-pore membrane on a large-pore substrate, simultaneously casting multiple layers of different pore sizes, stacking layers of different pore sizes together, and utilizing thermal-induced phase separation (TIPS or melt casting) (where the polymer is heated above its melting point, dissolved in a porogen, and phase separation is induced by cooling). 【0018】 In other examples, the pad includes a single polymer layer. FIG. 3 shows a schematic view of another exemplary pad 300 suitable for use as the pad 104 of FIG. 1. The pad 300 includes a single polymer layer 302 configured to contact a substrate 306. In some such examples, both hydrolysis and complexation are configured to occur in the same layer. In still other examples, the pad includes three or more layers. 【0019】 Referring again to FIGS. 2A-2B, in some examples, the first polymer layer 202 may be relatively thin compared to the second pad and may be configured for hydrolysis of the material removed in the planarization process (e.g., oxidation of metal species in some examples). Thus, the first polymer layer 202 may include relatively large pores, may be hydrophilic, and may be surface modified to functionalize the polymer surface, thereby enabling the polymer of the first polymer layer 202 to participate in the hydrolysis reaction. In some such examples, the first layer may have a thickness in the range of 0.1 micron to 5 microns. In other examples, the first layer can have any other suitable thickness (e.g., a thickness less than 0.1 micron or greater than 5 microns). In still other examples, the first polymer layer 202 can be non-porous. For example, as will be described in more detail below, the first polymer layer may include a textured surface that provides additional surface area for abrasive-free planarization chemistry. 【0020】 In some examples, the second polymer layer 204 may be relatively thicker than the first layer and may have relatively smaller pores than the first layer. In some examples, the second layer may be configured to retain the material removed by the first layer. For example, the second layer may include a surface chemically modified by a metal complexing agent adsorbed or bonded to the second layer within the pores to retain metal ions removed from the substrate. In some examples, the second layer may have a thickness of several microns to 3 mm, and in more specific examples, a thickness of 40 microns to 2 mm. 【0021】 Figures 2A-2B also depict the contact between substrate 206 and pad 200. As shown in Figures 2A-2B, the topologically high regions of substrate 206 contact pad 200, and pad 200 does not contact the topologically low regions of the substrate. Using a relatively low pressure of substrate 206 against pad 200, in combination with a planarizing chemical located within pad 200 rather than within the space between the pad and the substrate, serves to achieve removal of material from the topologically high regions of substrate 206 at a higher rate as the topologically high regions are in contact with a hydrolytic and / or complexing environment within the pad, compared to or even excluding the topologically low regions. 【0022】 In Figures 2A-2B, a pressure is applied through substrate 206 to press substrate 206 against pad 200. In some examples, pad 200 is compressed by only the weight of substrate 206. In other examples, an additional force is applied to substrate 206 (e.g., via substrate holder 106 of FIG. 1) to press substrate 206 against pad 200. Such force can cause compression of pad 200 as shown in FIG. 2B. In some examples, as introduced above, the second polymer layer 204 is configured to provide compressibility, and the first polymer layer 202 can have a porous and / or textured surface configured to remove material during a non-abrasive chemical planarization process. 【0023】 Furthermore, the first and / or second layers may be designed to have mechanical attributes such that they have sufficient rigidity to handle wafer loads and downward forces / applied pressures. In some examples, the first and / or second polymer layers may have a storage modulus of 15 MPa to 1200 MPa. More specific examples include a storage modulus of 400 to 800 MPa. In some examples, the first and / or second polymer layers may have a loss modulus of 100 to 600 MPa. More specific examples include a loss modulus of 150 to 500 MPa. In some examples, the first and / or second polymer layers may have a Tan delta (loss divided by storage) of 0.2 to 0.9. More specific examples include 0.4 to 0.8. In some examples, the first and / or second polymer layers may have a compressibility of less than 5% and / or a surface tension of less than 40 mN / m. The viscoelastic properties and physical attributes of the first polymer layer and / or the second polymer layer can be determined by standard dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) methods. 【0024】 In some examples, as described above, the second polymer layer 204 is more compressible than the first polymer layer 202. The first polymer layer 202 has a thickness 208A in Figure 2A before compression. After compression, the first polymer layer 202 has a second thickness 208B which is substantially the same as the first thickness 208A. In contrast, the second polymer layer 204 has a first thickness 210A before compression. The second polymer layer 204 has a second thickness 210B in Figure 2B which is smaller than the first thickness 210A in Figure 2A. In this way, the second polymer layer 204 can absorb compressive forces, and the first polymer layer 202 maintains a flat substrate-facing surface. In other examples, the first polymer layer 202 is more compressible than the second polymer layer 204. In this way, the second polymer layer 204 can function as a relatively firm "floor" supporting the first polymer layer 202 against the substrate 206. 【0025】 The first and second layers may contain one or more suitable materials. In some examples, the first polymer layer 202 and / or the second polymer layer 204 may contain one or more of polyurethane, polyanhydride, polycarbonate, polyacrylate, polysulfone, polyester, polyacrylonitrile, polyethersulfone, polyarylsulfone, polyacrylonitrile, epoxy, and / or polyvinylidene fluoride. Furthermore, in some examples, the first and / or second layers may have a Shore A hardness of 60–90 or a Shore D hardness of 30–60. In other examples, the first and / or second layers may have hardness values ​​outside these ranges. All ranges described herein include endpoint values. 【0026】 In some examples, the first layer comprises a thermoplastic material and the second layer comprises a thermosetting material. In some such examples, the second polymer layer 204 can be formed from a thermosetting polymer with higher crosslinking properties than the first polymer layer 202. As described in more detail below, the thermoplastic material can be 3D printed onto the second polymer layer 204 or formed by other methods more controlled than casting or injection molding. This allows for fine control over the structure and physical properties of the pad. In further examples, both the first and second layers can be formed from thermosetting materials, or both layers can be formed from thermoplastic materials. 【0027】 As described above, the first layer and / or the second layer may optionally contain a porous polymer. In some examples, pores are formed in the first layer and / or the second layer using TIPS or molten casting. Other techniques for forming pores in a polymer include introducing a blowing agent such as vapor and / or other gases (e.g., air, carbon dioxide, or nitrogen) to form bubbles within the molten polymer before it solidifies. 【0028】 In some more specific examples, the first polymer layer 202 has a smaller pore fraction than the second polymer layer 204. For example, the first layer may have an average pore diameter in the range of 1 nm to 1000 nm, preferably 30 nm to 200 nm. The second layer may also have an average pore diameter in the range of 5 nm to 1000 nm, preferably 200 nm to 1000 nm. In such examples, the second polymer layer 204 can provide adequate compressibility to accommodate the deformation of the first polymer layer 202. In other examples, the first polymer layer 202 has a larger pore fraction than the second polymer layer 204. In yet another example, one or more of the first polymer layer 202 and / or the second polymer layer 204 are non-porous. 【0029】 In some examples, the first layer includes a textured substrate-facing surface. Figure 4 shows a schematic diagram of another exemplary pad 400 suitable for use as pad 104 in Figure 1. Pad 400 includes a first polymer layer 402 and a second polymer layer 404. The first polymer layer 402 includes a textured substrate-facing surface 406 configured to contact the substrate during non-abrasive chemical planarization. The textured substrate-facing surface 406 includes multiple structures 408 such as bumps, ridges, or grooves that can cause friction between pad 400 and the substrate, which can result in the removal of material from the substrate. Furthermore, the textured surface can compensate for the lack of porosity by providing surface area for chemical reactions and / or channels that guide the planarization fluid during the process. 【0030】 As described in more detail below with reference to Figures 5A and 5B, the first polymer layer and / or the second polymer layer contain multiple reactive units covalently bonded within the polymer chain. Each reactive unit contains a functional group. Figures 5A and 5B schematically illustrate the incorporation of functional groups into the polymer. In some examples, the functional group contains hydrolyzing agents and / or complexing agents for performing non-abrasive chemical planarization. In some examples, the functional group contains one or more of carboxylic acids, amines, sulfonic acids, alcohols, phosphonic acids, amides, or polyethylene. In some more specific examples, the functional group contains one or more of iminodisuccinic acid, ethylenediaminedisuccinic acid, glutamic acid, methylglycine diacetic acid, dicyanamide, or polydiallyldimethylammonium chloride. Such chemical species can also be used as chelating agents separated from the pad, in addition to or instead of functionalizing the pad with such chemical species. In other examples, any other suitable functionalization can be performed to impart any desired chemical functionality to the pad. Other examples of functional groups include, but are not limited to, -COOCH2CH2OH, -N(CH2CH2OH)2, and -CONHR. 【0031】 In some examples, the polymer layer contains a hybrid distribution of covalently bonded functional groups and freely dispersed functional groups within the polymer matrix. Thus, the dispersed species can be released upon contact with the planarizing solution to aid in planarization. For example, oxalic acid can be dissolved in the polymer blend during pad manufacturing so that it can be released into the polishing medium during planarization. The two -COO groups from the oxalic acid facilitate the complexation of Cu, promoting Cu removal. In this way, covalently functionalized pads can increase the rate of material removal. Furthermore, as long as the dispersed species are not limited and the surface irregularities of the pad maintain their integrity over multiple polishing cycles, the process can be repeated without readjusting the pad, as no abrasives are used. The polishing process remains abrasive-free when the conditioning process is used to mechanically polish the pad. In some such approaches where polishing conditioning is performed, the pad may contain surface grooves or channels to facilitate the removal of polymer debris during conditioning. The advantages still apply to low-defect polishing processes as well, due to the absence of abrasives. Environmental benefits are evident during the polishing process, as spills can be chemically treated for the recovery of chemical species and water. Polymer residues from polishing conditioning can be separated before environmental disposal. 【0032】 The polymer of the pad can be functionalized using any suitable method. In some examples, the polymer of the pad can be functionalized during polymer synthesis. Figures 5A and 5B schematically illustrate the incorporation of functional groups into the polymer. In scheme (1), the monomer is bonded to a bifunctional reactive molecule containing the target functional group. Polymerization distributes the target functional group throughout the polymer (including within the solid mass of the polymer). In this way, the functional group is uniformly incorporated throughout the polymer layer. One potential advantage of this approach is that the functional group is present on the pore surface of the entire pad. Furthermore, mechanical wear and / or chemical degradation will expose additional functional groups beneath the substrate-facing surface, allowing the pad to operate longer than a pad lacking internal functional groups. In addition, single-layer pads can be manufactured in a single step, thereby reducing manufacturing time and cost compared to pads with two or more layers. 【0033】 Monomers suitable for generating crosslinked polymer networks using curing agents or functionalized reactive molecules include monomers having at least two reaction sites. Some examples of suitable monomers, as shown in Figure 6, include diisocyanates (e.g., 4,4'-methylenebis(phenylisocyanate), triene-2,4-diisocyanate, and hexamethyldiisocyanate), dieps (e.g., 1,4-butanediol diglycidyl ether, bisphenol A propoxylate diglycidyl ether, and (2-ethyl-2(hydroxymethyl))-1,3-propanediol polymer with (chloromethyl)oxirane), and anhydrides (e.g., pyromellitic dianhydride, ethylenediaminetetraacetic acid dianhydride, diethylenetriaminepentaacetic acid dianhydride). In some examples, such monomers react with ethylene glycol and / or substituted forms of ethylene glycol (e.g., glyceric acid) to form polyurethanes containing unreacted carboxylic acid groups. These carboxylic acids can function as chelating ligands for Cu removal during the polishing process. 【0034】 In some examples, the polymer layer contains polyurethane. In some such examples, the functional group is located on the isocyanate moiety of the polyurethane. The reaction of a hydroxyl group or amine group with the isocyanate can produce urethane bonds in the polymer backbone. Some examples of suitable molecules that can react with diisocyanate monomers include polyols (e.g., glyceric acid). In some such examples, the functional group is located on the polyol moiety of the polyurethane. Other examples of suitable molecules that can react with diisocyanate monomers include 2-2'-bis(hydroxymethyl)propionic acid and 3,4-dihydroxybenzoic acid. In some such examples, the acid moiety can function as a chelating functional group (e.g., for Cu removal during a polishing process). 【0035】 In other examples, the polymer layer contains polyanhydride. In some such examples, the functional groups are located in the anhydride portion of the polyanhydride. Polyanhydride can be formed by condensation between two carboxylic acid groups, resulting in the removal of water molecules. The anhydride portion makes the polyanhydride more reactive and easily hydrolyzable than other polymers (e.g., polyurethane). This can result in a biodegradable polymer network that reduces the environmental impact of waste. In some such examples, the polyanhydride further contains a polyol portion covalently bonded to the polyanhydride. In some such examples, the functional groups are located additionally or alternatively in the polyol portion. Polyols can be incorporated into polyanhydride-based systems as additives or modifiers. For example, polyols can be used as plasticizers to increase the flexibility of polyanhydride. Polyols can also be used as components in copolymers, such as copolymers containing polyanhydride and polyester bonds. This can result in hybrid materials with customized properties (e.g., flexibility and compressibility) tuned for chemical planarization. 【0036】 In other examples, the functional polymer network is formed using a curing agent and / or crosslinking agent that contains the target functional group, either additionally or alternatively. In yet another example, the functional polymer is crosslinked with a crosslinking agent that does not contain the target functional group. Crosslinking results in a stronger, more rigid three-dimensional polymer network than non-crosslinked polymers. 【0037】 In some such examples, the polymer layer contains epoxy. Epoxy can be formed by treating a precursor molecule containing epoxide functional groups with a curing agent. The curing agent crosslinks the precursor molecule to form a three-dimensional network structure. In some such examples, the functional groups are located on the epoxide portion of the epoxy. In other examples, the functional groups are located additionally or alternatively on the curing agent and / or polyol bonded within the epoxy chain. As described above, polyols can be incorporated into the polymer layer to modulate one or more properties of the polymer, such as flexibility and toughness, viscosity, adhesion, and hydrophobicity. In some examples, the addition of polyols or other additives can change the rate or degree of crosslinking, which can also be used to modulate the properties of the polymer. 【0038】 Referring again to Figures 5A and 5B, in some examples, the functional groups are separated by oligomeric segments of the polymer chain. For example, in scheme (2), monomers are bonded to a chain extender to form an extended prepolymer molecule. The extended prepolymer molecule is polymerized in the presence of a bifunctional reactive molecule containing the target functional group to form a functional polymer network as shown in Figures 5A and 5B. As a result, the functional groups are incorporated into the polymer network at extended intervals, and the prepolymer molecules are bonded together. 【0039】 Polymers can be functionalized after polymerization, either additionally or alternatively. Scheme (3) shows an example of post-polymerization functionalization. For example, a bifunctional reactive molecule containing a target functional group can be bonded to the synthesized polymer. In some such examples, the functional group is bonded to the substrate-facing surface of the polymer layer. For example, the functional group can be bonded to the substrate-facing surface of the first polymer layer 202 in Figures 2A-2B. As an example, a porous polyvinylidene fluoride (PVDF) layer or other suitable layer may be functionalized with a chelating agent such as poly(acrylic acid) to complexate metal ions after removal from the substrate. In the example of Figures 2A-2B, the porous PVDF layer can be used as either the first or second layer. 【0040】 In some examples, the first polymer layer 202 in Figures 2A-2B is functionalized, while the second polymer layer 204 is not. This can save costs compared to functionalizing the entire pad and result in faster and / or more efficient manufacturing. In other examples, as described above, two or more surfaces of the pad can be functionalized, which may additionally or alternatively include one or more surfaces of the first polymer layer 202 and the second polymer layer 204. It will also be understood that the first polymer layer and / or the second polymer layer may contain different functional groups. 【0041】 In some cases, polymers may be functionalized by coating, where the functional groups are not crosslinked to the polymer substrate but are instead adsorbed. For example, a polymer may be functionalized by adsorbing reactive molecules containing functional groups using a suitable solvent system. In some cases, the solvent system can cause swelling of the polymer layer, allowing the functional groups to be incorporated into at least a portion of the bulk volume of the polymer layer. 【0042】 Furthermore, when a functionalized polymer is used in a pad, the functionalization can be regenerated, for example, by adding new functional groups in situ (e.g., via a planarization solution distribution mechanism) to regenerate the functional groups. Further embodiments of regenerating functionalization are described in detail in U.S. Patent Application No. 17 / 729,805, filed April 26, 2022, entitled “PAD SURFACE REGENERATION AND METAL RECOVERY,” the entire contents of which are incorporated herein by reference for all purposes. 【0043】 Figures 7A and 7B show flowcharts illustrating an exemplary method 700 for forming a pad for performing non-abrasive chemical planarization of a substrate. A further description of method 700 is provided with reference to Figures 1 through 6 above. It will be understood that method 700 can be performed in other circumstances as well. 【0044】 In 702, method 700 includes the step of forming a pad for performing non-abrasive chemical planarization of a substrate. The pad comprises a polymer layer having functional groups covalently bonded to a polymer backbone, the functional groups comprising one or more complexing agents or hydrolyzing agents for performing non-abrasive chemical planarization. Figures 2A-2B show examples of pads 200 that can be formed by method 700 in Figures 7A-7B. 【0045】 The pads may be formed in any suitable manner. In some examples, in 704, the step of forming the pads involves reacting multiple reactive units with multiple monomer units, where one or more of the multiple reactive units or multiple monomer units contain a functional group. Figures 5 and 6 show some examples of suitable monomers. In scheme (1) of Figures 5A and 5B, polymerization of a bifunctional reactive molecule containing a target functional group with a monomer results in a distribution of the target functional group throughout the polymer. 【0046】 In another example, in 706, the step of forming a pad involves reacting multiple reactive units with multiple oligomeric segments, where one or more of the multiple reactive units or multiple oligomeric segments contain a functional group. For example, in scheme (2) shown in Figures 5A-5B, monomers are bonded to a chain extender to form an extended prepolymer molecule. The extended prepolymer molecule is polymerized in the presence of a bifunctional reactive molecule containing a target functional group to form a functionalized polymer. 【0047】 In some examples, in 708, the step of forming a pad includes casting a polymer layer using a prepolymer and curing the prepolymer. For example, the prepolymer can be formed as described above with reference to Figures 5A-5B. The prepolymer may be more viscous than a solution of monomer units and therefore easier to handle and pour into a mold than monomer units. This allows for a simpler and more efficient casting process, especially for complex or intricate shapes. The prepolymer can be formulated with specific compositions and properties to control factors such as hardness, flexibility, elongation, and curing time. The prepolymer can be designed to cure at ambient temperature or with minimal heat input, simplifying the casting process. This allows the polymer to cure at lower temperatures, reducing energy consumption and enabling casting in heat-sensitive molds. Furthermore, since the prepolymer can be manufactured under controlled conditions, the use of the prepolymer can result in more uniform batch-to-batch production than polymerization from scratch. Casting with the prepolymer also allows for precise metering and control of material usage. This minimizes material waste and contributes to cost-effectiveness in production. 【0048】 In 710, in some examples, the step of forming a pad includes molding a polymer layer. For example, a polymer layer can be formed by molding a prepolymer as described above. 【0049】 In some examples, in 712, the step of forming a pad includes reacting the surface of the polymer layer with reactive units containing functional groups. For example, the functional groups can be bonded to the substrate-facing surface of the first polymer layer 202 in Figures 2A-2B. 【0050】 In 714, in some examples, the step of forming a pad includes swelling a polymer layer with a solvent and then incorporating reactive units containing functional groups into at least a portion of the bulk volume of the polymer layer. For example, the polymer layer can be treated with a solvent system that causes swelling of the polymer layer. This makes it possible to incorporate functional groups into at least a portion of the bulk volume of the polymer layer. 【0051】 In some examples, in 716, the step of forming a polymer layer includes forming a polyurethane, where the functional groups are located on the isocyanate portion of the polyurethane. For example, as described above with reference to Figure 6, the functional groups can be located on isocyanates such as 4,4'-methylenebis(phenyl isocyanate), triene-2,4-diisocyanate, and hexamethyl diisocyanate. The reaction of a hydroxyl group or amine group with an isocyanate can generate urethane bonds in the polymer backbone. In this way, the functional groups can be incorporated into the polyurethane. 【0052】 In 718, in some examples, the step of forming a polymer layer includes forming a polyurethane, where the functional groups are located on the polyol portion of the polyurethane. For example, as described above, a polyurethane can be formed by reacting a polyol with an isocyanate. Functional groups can be provided on the polyol, thereby incorporating the functional groups into the polyurethane. 【0053】 In some examples, in 720, the step of forming a polymer layer includes forming a polyanhydride, where the functional groups are located in the anhydride portion of the polyanhydride. For example, as described above with reference to Figure 6, the functional groups can be located in anhydrides such as pyromellitic dianhydride, ethylenediaminetetraacetic acid dianhydride, and diethylenetriaminepentaacetic acid dianhydride. In this way, the functional groups can be incorporated into the polyanhydride. 【0054】 In 722, in some examples, the step of forming a polymer layer includes forming a polyanhydride, where the functional groups are located on the polyol portion of the polyanhydride. For example, the polyol can be incorporated into the polyanhydride-based system as an additive or modifier. In this way, the functional groups are incorporated into the polymer layer by providing them on the polyol. 【0055】 In some examples, in 724, the step of forming a polymer layer includes forming an epoxy, where the functional groups are located on the epoxide portion of the epoxy. For example, as described above with reference to Figure 6, the functional groups can be located on the epoxy. Thus, the crosslinking of the epoxy results in the formation of a polymer containing the functional groups. 【0056】 In 726, in some examples, the step of forming a polymer layer includes forming an epoxy, where the functional groups are located on a polyol bonded within the epoxy chain. The polyol can function as a curing agent or an additive / modifier. Thereafter, polymerization incorporates the polyol and functional groups into the polymer matrix. 【0057】 Referring here to Figure 7B, in some examples, in 728, method 700 further includes the step of forming a second polymer layer located on the side of the first polymer layer opposite to the substrate contact side of the first polymer layer. In some examples, the first polymer layer 202 and the second polymer layer 204 are formed integrally as a double layer in a single process. In some such examples, the first polymer layer 202 and the second polymer layer 204 are formed by liquid casting, injection molding, extrusion, additive manufacturing, or a combination thereof. 【0058】 In some examples, in 730, the step of forming the first and second polymer layers includes forming the first and second polymer layers in a single injection while varying the composition. For example, the composition of the liquid injected into the mold during the liquid casting process can be changed midway through the liquid casting process. This results in a monolithic structure having two distinct layers produced in a single process, thereby allowing for adjustment of the composition and other properties of the porous pad during manufacturing. The use of a single process to form both layers also reduces costs and increases process efficiency compared to forming each layer separately. 【0059】 In other examples, the first polymer layer 202 and the second polymer layer 204 are manufactured in separate steps. In some such examples, the first polymer layer 202 and the second polymer layer 204 are formed by liquid casting, injection molding, extrusion, additive manufacturing, or a combination thereof. 【0060】 In some examples, as in 732, Method 700 further includes the step of forming a first polymer layer and then placing the first polymer layer in a mold. Method 700 further includes the step of injecting a polymer for a second polymer layer into the mold to incorporate the first polymer layer into the second polymer layer by insert molding. This allows the first layer to be inspected before forming the second layer and allows for finer control over the formation of the first and second layers. In some examples, it may be faster, cheaper, and / or more efficient to manufacture the first and second layers separately than in a single step as described above. 【0061】 In some examples, method 700 includes the step of covalently bonding a second number of reactive units within the polymer chain of the second polymer layer. For example, the second polymer layer 204 in Figures 2A-2B can be functionalized in the same manner as described above. 【0062】 In some examples, in 736, the step of forming a first polymer layer includes forming the first polymer layer using a thermoplastic material, and the step of forming a second polymer layer includes forming the second polymer layer using a thermosetting material. For example, the first polymer layer 202 in Figures 2A-2B may contain a thermoplastic material, and the second polymer layer 204 may contain a thermosetting material, or vice versa. This makes it possible for each layer to have a tunable molecular structure and physical properties (e.g., compressibility and toughness). 【0063】 In some examples in 738, method 700 includes the step of using a foaming agent to form pores in at least one of a first polymer layer or a second polymer layer. This makes it possible to form a porous polymer structure which can have a larger surface area (including the surface of the pores) and greater compressibility than a solid polymer. 【0064】 In some examples, in 740, method 700 includes the step of forming a textured surface on a first polymer layer. For example, the pad 400 in Figure 4 includes a textured substrate-facing surface 406. The textured surface can accelerate the removal of material from the substrate and increases the surface area compared to a smooth substrate-facing surface. 【0065】 Figure 8 shows a schematic diagram of another exemplary pad 800 suitable for use as pad 104 in Figure 1. Pad 800 comprises a single polymer layer 802. However, as mentioned above, in other examples, pad 800 may comprise any other suitable number of layers (e.g., two or more layers). Pad 800 comprises multiple microspheres 804 and / or multiple fillers 806. The microspheres 804 and / or fillers 806 are dispersed through the polymer layer 802 during pad manufacturing. Each microsphere 804 and filler 806 comprises a polymer and functional groups bonded to the polymer (e.g., the functional groups mentioned above with reference to Figures 5-6). However, the microspheres 804 and fillers 806 are not covalently bonded to the polymer layer 802 of pad 800. Instead, the microspheres 804 and fillers 806 can be retained within the polymer layer 802 by electrostatic forces, hydrophilic / hydrophobic interactions, van der Waals forces, mechanical interlocks, etc. Furthermore, the microspheres 804 and fillers 806 can be chemically regenerated. This makes it possible to repeatedly use the functional groups on multiple wafers. 【0066】 This disclosure is presented with reference, as an example, to relevant drawings. Components, process steps, and other elements that may be substantially the same in one or more drawings are co-identified and described with minimal repetition. However, it should be noted that even co-identified elements may differ to some extent. It should also be noted that some drawings are schematic and may not be drawn to scale. The scales, aspect ratios, and number of components in the various drawings shown may be intentionally distorted to make certain features or relationships more visible. 【0067】 As used herein, "and / or" is defined as inclusive, i.e., ∨, as specified by the following truth table. [Table 1] 【0068】 As used herein, the term "one or more of A or B" includes A, B, or a combination of A and B. The term "one or more of A, B, or C" is equivalent to A, B, and / or C. Therefore, as used herein, "one or more of A, B, or C" includes A individually, B individually, C individually, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C. 【0069】 It will be understood that the configurations and / or approaches described herein are essentially illustrative, and these specific embodiments or examples should not be considered restrictively, as numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of policies. Therefore, the various operations illustrated and / or described may be performed in the order illustrated and / or described, in other orders, in parallel, or in abbreviation. Similarly, the order of the processes described above is modifiable. 【0070】 The subject matter of this disclosure includes all novel and non-obvious combinations and partial combinations thereof of the various processes, systems and configurations disclosed herein, as well as other features, functions, operations, and / or characteristics, and all their equivalents.

Claims

[Claim 1] A pad for performing non-abrasive chemical planarization of a substrate, A polymer layer configured to come into contact with the substrate during the abrasive chemical planarization, comprising a plurality of reactive units covalently bonded within the polymer chain, each reactive unit comprising a functional group containing one or more complexing agents or hydrolyzing agents for performing the abrasive chemical planarization. Includes pads. [Claim 2] The pad according to claim 1, wherein each reactive unit contains the functional group. [Claim 3] The pad according to claim 1, wherein the functional group is separated by the oligomeric segment of the polymer chain. [Claim 4] The pad according to claim 1, wherein the functional group is uniformly incorporated throughout the polymer layer. [Claim 5] The pad according to claim 1, wherein the functional group is bonded to the substrate-facing surface of the polymer layer. [Claim 6] The pad according to claim 1, wherein the polymer layer contains polyurethane, and the functional group is located in the isocyanate portion of the polyurethane. [Claim 7] The pad according to claim 1, wherein the polymer layer contains polyurethane, and the functional group is located in the polyol portion of the polyurethane. [Claim 8] The pad according to claim 1, wherein the polymer layer contains a polyanhydride, and the functional group is located in the anhydride portion of the polyanhydride. [Claim 9] The pad according to claim 1, wherein the polymer layer contains a polyanhydride, and the functional group is located in the polyol portion of the polyanhydride. [Claim 10] The pad according to claim 1, wherein the polymer layer contains epoxy, and the functional group is located in the epoxide portion of the epoxy. [Claim 11] The pad according to claim 1, wherein the polymer layer contains epoxy, and the functional group is located on a polyol bonded within the epoxy chain. [Claim 12] The pad according to claim 1, wherein the functional group comprises one or more of carboxylic acids, amines, sulfonic acids, alcohols, phosphonic acids, amides, or polyethylene. [Claim 13] The pad according to claim 1, wherein the functional group comprises one or more of iminodisuccinic acid, ethylenediaminedisuccinic acid, glutamic acid, methylglycinediacetic acid, dicyanamide, or polydiallyldimethylammonium chloride. [Claim 14] The pad according to claim 1, wherein the pad comprises a single polymer layer. [Claim 15] The pad according to claim 1, wherein the pad comprises two or more layers including the polymer layer. [Claim 16] The pad according to claim 1, wherein the pad comprises one or more microspheres or fillers, each of which comprises a polymer and a functional group bonded to the polymer, and the one or more of the microspheres or fillers are not covalently bonded to the polymer layer of the pad. [Claim 17] A pad for performing non-abrasive chemical planarization of a substrate, A first polymer layer configured to contact the substrate during the abrasive chemical planarization, comprising a plurality of reactive units covalently bonded within the polymer chain, each reactive unit comprising a functional group containing one or more complexing agents or hydrolyzing agents for performing the abrasive chemical planarization, A second polymer layer located on the side of the first polymer layer opposite to the side of the first polymer layer that is in contact with the substrate, and Includes pads. [Claim 18] The pad according to claim 17, wherein the first polymer layer comprises a thermoplastic material and the second polymer layer comprises a thermosetting material. [Claim 19] The pad according to claim 17, wherein the first polymer layer and the second polymer layer each contain a porous polymer. [Claim 20] The pad according to claim 19, wherein the first polymer layer has a smaller pore fraction than the second polymer layer. [Claim 21] The pad according to claim 17, wherein the first polymer layer is nonporous and the second polymer layer comprises a porous polymer. [Claim 22] The pad according to claim 17, wherein the first polymer layer includes a textured surface facing a substrate. [Claim 23] The pad according to claim 17, wherein the second polymer layer comprises a second plurality of reactive units covalently bonded within the polymer chain of the second polymer layer. [Claim 24] The pad according to claim 17, wherein the functional group comprises one or more of carboxylic acids, amines, sulfonic acids, alcohols, phosphonic acids, amides, or polyethylene. [Claim 25] The pad according to claim 17, wherein the functional group comprises one or more of iminodisuccinic acid, ethylenediaminedisuccinic acid, glutamic acid, methylglycinediacetic acid, dicyanamide, or polydiallyldimethylammonium chloride. [Claim 26] The pad according to claim 17, wherein the second polymer layer is more compressible than the first polymer layer. [Claim 27] A step of forming a pad for performing non-abrasive chemical planarization of a substrate, wherein the pad comprises a polymer layer having functional groups covalently bonded to a polymer backbone, and the functional groups comprising one or more complexing agents or hydrolyzing agents for performing the non-abrasive chemical planarization. Methods that include... [Claim 28] The method according to claim 27, wherein the step of forming the pad includes reacting a plurality of reactive units with a plurality of monomer units, and one or more of the plurality of reactive units or the plurality of monomer units includes the functional group. [Claim 29] The method according to claim 27, the method according to claim 26, wherein the step of forming the pad includes reacting a plurality of reactive units with a plurality of oligomer segments, and one or more of the plurality of reactive units or the plurality of oligomer segments include the functional group. [Claim 30] The method according to claim 27, wherein the step of forming the pad includes casting the polymer layer using a prepolymer and curing the prepolymer. [Claim 31] The method according to claim 27, wherein the step of forming the pad includes molding the polymer layer. [Claim 32] The method according to claim 27, wherein the step of forming the pad includes reacting the surface of the polymer layer with a reactive unit containing the functional group. [Claim 33] The method according to claim 27, wherein the step of forming the pad comprises swelling the polymer layer with a solvent, and then incorporating the reactive units containing the functional group into at least a portion of the bulk volume of the polymer layer. [Claim 34] The method according to claim 27, wherein the step of forming the polymer layer includes forming a polyurethane, and the functional group is located in the isocyanate portion of the polyurethane. [Claim 35] The method according to claim 27, wherein the step of forming the polymer layer includes forming a polyurethane, and the functional group is located in the polyol portion of the polyurethane. [Claim 36] The method according to claim 27, wherein the step of forming the polymer layer includes forming a polyanhydride, and the functional group is located in the anhydride portion of the polyanhydride. [Claim 37] The method according to claim 27, wherein the step of forming the polymer layer includes forming a polyanhydride, and the functional group is located in the polyol portion of the polyanhydride. [Claim 38] The method according to claim 27, wherein the step of forming the polymer layer includes forming an epoxy, and the functional group is located in the epoxide portion of the epoxy. [Claim 39] The method according to claim 27, wherein the step of forming the polymer layer comprises forming an epoxy, wherein the functional group is located in a polyol bonded within the epoxy chain. [Claim 40] The method according to claim 27, wherein the polymer layer comprises a first polymer layer, and the method further comprises the step of forming a second polymer layer located on the side of the first polymer layer opposite to the side of the first polymer layer that is in contact with the substrate. [Claim 41] The method according to claim 40, wherein the step of forming the first polymer layer comprises forming the first polymer layer using a thermoplastic material, and the step of forming the second polymer layer comprises forming the second polymer layer using a thermosetting material. [Claim 42] The method according to claim 40, further comprising the step of using a foaming agent to form pores in at least one of the first polymer layer or the second polymer layer. [Claim 43] The method according to claim 40, wherein the step of forming the first polymer and the second polymer layer comprises forming the first polymer and the second polymer layer in a single injection while varying the composition. [Claim 44] After forming the first polymer layer, the first polymer layer is placed inside the mold. The steps include: injecting the polymer for the second polymer layer into the mold and incorporating the first polymer layer into the second polymer layer by insert molding; The method according to claim 40, further comprising: [Claim 45] The method according to claim 40, further comprising the step of forming a textured surface on the first polymer layer. [Claim 46] The method according to claim 40, further comprising the step of covalently bonding a second plurality of reactive units in the polymer chain of the second polymer layer.

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