Global planarization method

Abstract

Compositions and methods for global planarization of microelectronic substrates are provided. The method includes applying a crosslinking modifier composition to a surface of a substrate, or any intermediate layer on the surface of the substrate. Subsequently, a planarization material may be applied to the cross-linking modifier layer, which affects the degree of cross-linking in the planarized layer. Depending on the specific topography of the underlying substrate (or intermediate layer), different amounts of planarized material are removed during a subsequent development back-off step, thereby eliminating deviations that typically exist between regions of different topography densities. The result is an efficient global planarization method that is time and cost efficient.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 539,587, filed September 20, 2023, entitled “METHODS OF GLOBAL PLANARIZATION”, which is incorporated herein by reference in its entirety. Background Technology Technical Field

[0003] This disclosure broadly relates to methods for manufacturing microelectronic structures, and more specifically, to compositions and methods for globally planarizing a substrate during photolithography. Background Technology

[0004] In microelectronics manufacturing, integrated circuits and other semiconductor devices are typically manufactured by building multi-layered structures using sequential, bottom-up fabrication processes. For example, chips used in computers and other devices are usually manufactured in this manner. Various deposition, etching, and other processes can be used to achieve multi-layered features. Reliable devices require extremely fine tolerances. Meeting these tolerance requirements allows for a highly planarized top surface on which subsequent layers are built, with each subsequent layer built on top of the previous one.

[0005] For example, photolithography typically involves patterning multiple stacked layers. As industry standards shift towards increasingly smaller patterned features, the demands for precision and accuracy become increasingly stringent. At each stage, focusing the patterned image onto the surface being patterned can be compromised due to surface inhomogeneities. Furthermore, the increasingly limited depth of focus associated with using smaller wavelengths of light and the higher numerical aperture optics required to achieve very small features exacerbate this problem, amplifying the effects of even minute imperfections. As successive layers are generated and patterned, producing uniform, planar material on them becomes increasingly difficult, especially when the underlying layers have high aspect ratio morphologies (such as deep trenches and / or vias).

[0006] Chemical mechanical polishing (CMP) can be used to planarize semiconductor device layers, but CMP is time-consuming and increases device manufacturing costs. CMP also involves bringing the upper surface into contact with a rotating polishing pad. Poor adhesion between the surface layer and one or more underlying layers, as well as insufficient material strength to withstand the CMP process, makes it difficult to achieve desired results. In addition, CMP can introduce contaminants and other undesirable defects.

[0007] Another planarization method involves applying a thick coating of planarizing material to the topographic structure to obtain a flat top surface. However, a large overburden is undesirable for further processing steps. Other planarization materials and processes require several additional steps, such as reflow baking or plasma etching, to achieve planarization without leaving excessive overburden on the top of the structure. Even with these additional steps and increased costs, the results of this method can be improved.

[0008] Planarization can refer to local planarization or global planarization. Local planarization refers to the flattening of the upper surface of a small region within a substrate with a significantly larger area. Global planarization refers to the flattening of the upper surface of the entire device-yielding area of ​​the substrate. To date, efforts to achieve local planarization have included: adjusting the polymer composition to alter its properties (e.g., viscosity, surface tension, and / or thickness), and selecting different spin-coating parameters (e.g., ramp rate, rotation speed, and rotation time) to facilitate material flow from higher to lower planar regions. These have been relatively successful in achieving adequate local planarization, but commercial-scale global planarization (without additional polishing steps) has not yet been achieved. Therefore, improved global planarization methods using spin-coated materials remain needed in the fabrication of microelectronic devices. Summary of the Invention

[0009] This disclosure broadly relates to a method of forming a structure, the method comprising: providing a substrate, the substrate comprising a substrate surface; optionally forming one or more intermediate layers on the substrate surface, wherein the substrate surface, or if one or more intermediate layers are present, the uppermost surface of a top intermediate layer on the substrate surface comprises a first region of dense morphological features and a second region of sparse morphological features; applying a crosslinking modifier composition to the substrate surface, or if a top intermediate layer is present, to the uppermost surface of the top intermediate layer to form a crosslinking modifier layer, the crosslinking modifier layer covering at least a portion of the first region of dense morphological features and at least a portion of the second region of sparse morphological features; applying a planarization composition to the crosslinking modifier layer; heating the planarization composition to form a planarization layer having a first average thickness in the first region of dense morphological features and a second average thickness in the second region of sparse morphological features; and contacting the planarization layer with a solvent to reduce the first average thickness and the second average thickness, wherein the contact reduces the first average thickness more than the second average thickness.

[0010] This disclosure broadly relates to a method of forming a structure, the method comprising: optionally forming one or more intermediate layers on a substrate surface, wherein the substrate surface, or if the one or more intermediate layers are present, the uppermost surface of a top intermediate layer on the substrate surface includes a first region of dense morphological features and a second region of sparse morphological features located on the substrate surface, or if the top intermediate layer is present, the uppermost surface of the top intermediate layer, the crosslinking modifier layer covering at least a portion of the first region of dense morphological features and at least a portion of the second region of sparse morphological features; and applying a planarization composition onto the crosslinking modifier layer, the planarization composition... The composition comprises one or both of a crosslinkable polymer or a decrosslinkable polymer; the planarization composition is heated to form a planarization layer on the crosslinking modifier layer, wherein a crosslinking modified component is generated in situ within the crosslinking modifier layer during the heating; and at least a portion of the crosslinking modified component contacts the planarization layer, wherein the crosslinking modified component in contact with the planarization layer: (1) reduces the degree of crosslinking, the crosslinking being what the crosslinkable polymer would otherwise undergo during the heating process if the crosslinking modified component were not generated in the crosslinking modifier layer; and / or (2) decrosslinks at least some of the decrosslinkable polymers in the planarization layer.

[0011] This disclosure broadly relates to a structure comprising: a substrate having a substrate surface; one or more intermediate layers optionally present on the substrate surface, wherein the substrate surface, or if present, the uppermost surface of a top intermediate layer on the substrate surface, comprises a first region of dense morphological features and a second region of sparse morphological features; a crosslinking modifier layer located on at least a portion of the substrate surface, or if present, the uppermost surface of the top intermediate layer; and a non-patterned planarization layer located on at least a portion of the crosslinking modifier layer, wherein the non-patterned planarization layer is crosslinked in at least 95% of its entire volume, and wherein the deviation of the non-patterned planarization layer measured between the first region of dense morphological features and the second region of sparse morphological features is less than 30 nm. Attached Figure Description

[0012] Figure 1 This is a schematic diagram (not drawn to scale) illustrating some embodiments of a photolithographic stack using the global planarization compositions and methods described herein; Figure 2 This is a schematic diagram (not drawn to scale) illustrating some embodiments of a photolithographic stack using the disclosed global planarization composition and method; Figure 3aThis is a schematic diagram (not drawn to scale) showing some embodiments of a substrate with different morphological regions and a global planarization composition layer applied to each region, used to construct an equation for predicting deviations, as described in Example 9; Figure 3b The image is a cross-sectional SEM image showing a planarization layer applied to a substrate with several different morphological regions to verify the equation for the predicted bias, as described in Example 9; Figure 4 Several images of a chip with different topographic regions are provided, including a top view (lower left) and a magnified plan view (lower right) of the chip, as well as cross-sections (top) of different topographic regions; Figure 5 Several cross-sectional SEM images of two different topographic regions on a substrate are provided during each step of the planarization method described in Example 4. Figure 6 Several cross-sectional SEM images of different morphological regions on several substrates formed as described in Example 5 are provided; Figure 7 Several cross-sectional SEM images of different morphological regions on several substrates formed as described in Example 6 are provided; Figure 8 Several cross-sectional SEM images of different morphological regions on two different substrates as described in Example 7 are provided; and Figure 9 Several cross-sectional SEM images of different morphological regions on two different substrates formed as described in Example 8 are provided. Detailed Implementation

[0013] This disclosure broadly relates to novel crosslinking modifier compositions and methods for achieving global planarization of microelectronic structures for photolithography using those compositions.

[0014] Composition

[0015] 1. A composition for a crosslinking modifier layer

[0016] The crosslinking modifier layer may contain at least one polymer capable of generating a crosslinking modifier component. Preferred polymers for the crosslinking modifier composition may be acid-generating or base-generating polymers. The polymer contains repeating monomers, including acid-generating or base-generating monomers, surface adhesion monomers, and solubility-enhancing monomers.

[0017] When the polymer used in the crosslinking modifier composition is a alkali-forming polymer, the polymer comprises at least one monomer containing an alkali-forming functional group. The alkali-forming functional group is any group that is itself a base (such as pyridine) or capable of forming a base upon exposure to heat (e.g., a thermal alkali-forming agent or "TBG") or light (e.g., a photo-alkali-forming agent or "PBG"). In both cases, the PBG or TBG group may be bonded to the monomer and can be considered part of its structure (and ultimately part of the polymer structure, as a side group and / or part of the polymer backbone). In some embodiments, the crosslinking modifier composition may contain less than about 0.5% by weight, preferably less than about 0.1% by weight, or more preferably less than about 0.01% by weight of a TBG or PBG compound independent of the alkali-forming polymer (i.e., not bonded to the alkali-forming polymer).

[0018] Examples of this alkalogenic functional group include those selected from amines, including C1 to C2. 12 More preferably, C1 to C6 aliphatic amines, and C5 to C 18 And more preferably C6 to C 16 Aromatic and / or heteroaromatic amines, or combinations thereof. Preferred heteroaromatic amines are 6- to 18-membered rings, and more preferably 6- to 12-membered rings. Examples of specific alkali-forming amine functional groups suitable for use in various embodiments of the present technology include, but are not limited to: hexylamine, monoethanolamine, 2-aminoethyl methacrylate hydrochloride, methacryl-L-lysine, N-[3-(N,N-dimethylamino)propyl]methacrylamide, N-[2-(N,N-dimethylamino)ethyl]methacrylamide, N-[3-(N,N-dimethylamino)propyl]acrylamide, 2-(N,N-dimethylamino)ethyl acrylate, 2-(N,N-diethylamino)ethyl methacrylate, 2-(N,N-dimethylamino)ethyl methacrylate, pyridine, vinylpyridine, aniline, 4,4′-oxodiphenylamine, or combinations thereof.

[0019] Examples of suitable monomers that can be connected to the alkali-generating functional group to provide the alkali-generating monomer include, but are not limited to, those selected from: acrylates, methacrylates, acrylamides, amides, aromatic amines and diamines, dianhydrides, acrylonitriles, esters, or combinations thereof.

[0020] When used, the alkali-generating monomer is preferably present in the polymer in the following amounts: about 0.5% to about 100%, preferably about 1% to about 50%, more preferably about 1% to about 20%, or more preferably about 1.5% to about 12.5%, or most preferably about 1% to about 10%, based on 100% of the total weight of the polymer.

[0021] When the polymer used in the crosslinking modifier composition is an acid-generating polymer, the polymer may contain repeating monomers including acid-generating functional groups. Examples of suitable acid-generating functional groups include photoacid-generating (“PAG”) functional groups or thermoacid-generating (“TAG”) functional groups. A PAG functional group is a functional group that generates acid upon exposure to light of a target wavelength, while a TAG group is a group that generates acid upon exposure to heat. In both cases, the PAG or TAG group may be bonded to the monomer and may be considered part of its structure (and ultimately part of the polymer structure, as a side group and / or part of the polymer backbone). In some embodiments, the crosslinking modifier composition may contain less than about 0.5% by weight, preferably less than about 0.1% by weight, or more preferably less than about 0.01% by weight of a TAG or PAG compound independent of the acid-generating polymer (i.e., not bonded to the acid-generating polymer).

[0022] Examples of suitable PAG functional groups may be selected from: onium salts (e.g., triphenylsulfonium (“TPS”) perfluorosulfonates, such as TPS nonafluorobutyrate, TPS trifluoromethanesulfonate); substituted onium salts (e.g., alkyl-substituted TPS nonafluorobutyrate (preferably C1-C8-substituted); tris(4-tert-butylphenyl)sulfonium perfluoro-1-butyrate); oxime-sulfonates / esters (e.g., Irgacure PAG 203, CGI PAG 19XX, N-hydroxynaphthalenediimide trifluoromethanesulfonate, N-hydroxy-5-norbornene-2,3-dicarboxylimide perfluoro-1-butyrate); triazines (e.g., 2-methyl-2-(2′-furanylethene)-4,6-bis(trichloromethyl)-1,3,5-triazine, 2-[(4′-methoxy)styryl]-4,6-bis(trichloromethyl)-1,3,5-triazine); or combinations thereof. Suitable TAG functional groups may be selected from ionic TAG functional groups, such as quaternary ammonium or tertiary amine blocked sulfuric acid (including fluorinated), nonionic TAG functional groups, such as N-hydroxynaphthalimide sulfonate, or combinations thereof.

[0023] The aforementioned acid functional groups (e.g., TAG or PAG groups) may be substituted onto (e.g., bonded to) one or more monomers selected from: acrylates, methacrylates, acrylamides, amides, aromatic amines and diamines, dianhydrides, acrylonitriles, esters, or combinations thereof. These monomers bonded to one or more TAG or PAG groups form acid-generating monomers, which can be used to form polymers as described herein.

[0024] Particularly preferred examples of acid-generating monomers include triphenylsulfonium 3-sulfopropyl methacrylate (“TPS-SPMA”, hereinafter the intermediate monomer of polymer B) and triphenylsulfonium 4-(methacryloyloxy)-2,3,5,6-tetrafluorobenzenesulfonate (“TPS-4FBSMA”, hereinafter the intermediate monomer of polymer C). The acid-generating monomers may be prepared according to the method disclosed in U.S. Patent No. 8,900,792, which is incorporated herein by reference in its entirety without inconsistency with this disclosure.

[0025] When used to form a polymer for crosslinking modifier composition, the acid-producing monomer may preferably be present in the polymer in the following amounts: about 0.1 wt% to about 99 wt%, preferably about 0.5 wt% to about 35 wt%, preferably about 0.5 wt% to about 20 wt%, more preferably about 1 wt% to about 10 wt%, based on the total weight of the polymer taken as 100%.

[0026] In some embodiments, the polymer used in the crosslinking modifier composition may also contain at least one surface adhesion monomer. This monomer helps promote adhesion (or surface bonding) of the polymer to a surface on which the polymer is applied. Suitable surface adhesion monomers include functional groups capable of interacting chemically or physically with the surface of the substrate to which the composition is applied (or the upper surface of the uppermost intermediate layer, if present). Therefore, it will be understood that different surface adhesion monomers can be used for different surfaces.

[0027] Preferred surface adhesion monomers include functional groups or portions selected from those of: hydroxyl groups (such as 2-hydroxyethyl methacrylate and / or hydroxypropyl methacrylate); epoxides (such as glycidyl methacrylate); carboxylic acids (such as methacrylic acid, acrylic acid, and / or mono-2-(methacryloyloxy)ethyl succinate); thiols (such as 2-(methylthio)ethyl methacrylate); silanes (such as 3-(trimethoxysilyl)propyl methacrylate); aldehydes (such as 3-[(4-vinylphenyl)methoxy]benzaldehyde); acetylacetonates (such as 2-(methacryloyloxy)ethyl acetoacetate); or combinations of one or more of the foregoing.

[0028] The surface adhesion monomer is preferably present in the polymer in the following amounts: about 1 to about 99% by weight, preferably about 2 to about 50% by weight, more preferably about 3 to about 25% by weight, more preferably about 5 to about 20% by weight, or even more preferably about 7.5 to about 15% by weight, based on 100% of the total weight of the polymer.

[0029] In some embodiments, the polymer used in the crosslinking modifier composition may further comprise a solubility-enhancing monomer, which may be useful if the selected acid- or alkali-generating monomer is not readily soluble in the selected solvent. The solubility-enhancing monomer, which may be inert, may have additional or alternative functions to alter or control the amount of acid or alkali generated by the polymer. Including a higher content of the solubility-enhancing monomer in the polymer can reduce the amount of acid or alkali generated. Preferred solubility-enhancing monomers may be selected from: styrene, methyl methacrylate, methylstyrene, 4-tert-butylstyrene, n-butyl methacrylate, benzyl methacrylate, or combinations thereof.

[0030] When used in acid-producing polymers, the solubility-enhancing monomer may be present in the polymer in the following amounts: about 1% to about 90% by weight of the polymer, preferably about 10% to about 80% by weight of the polymer, more preferably about 20% to 70%, or even more preferably about 25% to about 65% based on the total weight of the polymer taken as 100%.

[0031] When used in alkali-forming polymers, the solubility-enhancing monomer may be present in the following amounts: about 0% to about 99%, preferably about 30% to about 95%, or more preferably about 50% to about 95%, or even more preferably about 55% to about 90%, based on 100% of the total weight of the polymer.

[0032] Although the polymer may include other monomers besides the acid- or alkali-generating monomers, the surface adhesion monomers, and the solubility-enhancing monomers, in some embodiments, the polymer is essentially composed of only these three types of monomers, or even only these three types of monomers. Therefore, the polymer may include other monomers in amounts less than about 1% by weight, less than about 0.5% by weight, or less than about 0.1% by weight, based on a weight taken as 100% of the total polymer weight.

[0033] Polymers containing the aforementioned monomers can be synthesized by any suitable polymerization method, with free radical polymerization being a preferred method. In a preferred embodiment, the polymer is synthesized by free radical polymerization using azobisisobutyronitrile (AIBN) as an initiator in a solvent such as propylene glycol monomethyl ether (PGME). The free radical polymerization is preferably carried out using an initiator in an amount of about 1% to about 5% by weight of the monomer, more preferably about 2% by weight, and the polymerization is carried out at a temperature of 60°C to 90°C, or more preferably about 60 to about 75°C, for about 4 hours to about 24 hours, or about 8 hours to about 20 hours.

[0034] Preferred alkali-forming polymers suitable for use in the crosslinking modifier compositions according to some embodiments of the present technology are shown in polymer A below.

[0035]

[0036] Polymer A is formed using repeating monomers of 2-hydroxyethyl methacrylate (“HEMA”), 4-vinylpyridine, and methyl methacrylate. Polymer A preferably comprises about 5% to about 25% by weight (or more preferably about 7.5% to about 15% by weight) of HEMA monomer; about 1% to about 15% by weight (or more preferably about 1.5% to about 12.5% ​​by weight) of 4-vinylpyridine monomer; and about 65% to about 95% by weight (or more preferably about 75% to about 90% by weight) of methyl methacrylate monomer, all based on 100% of the total weight of the polymer.

[0037] Two preferred acid-producing polymers suitable for use in the crosslinking modifier compositions according to some embodiments of the present technology are shown below as polymers B and C.

[0038]

[0039] Polymer B comprises repeating monomers of HEMA, styrene, and TPS-SPMA, while polymer C comprises repeating monomers of HEMA, styrene, and TPS-4FBSMA. For polymer B or C, the polymer preferably comprises about 1% to about 20% by weight (more preferably about 5% to 10% by weight) of HEMA monomer; about 1% to 90% by weight (more preferably about 40% to about 60% by weight) of styrene monomer; and about 5% to about 95% by weight of PAG-containing monomers (TPS-SPMA and / or TPS-4FBSMA; more preferably about 40% to about 60% by weight), all based on a total weight of 100% of the polymer.

[0040] The weight-average molecular weight (Mw) range of the polymer (measured by gel permeation chromatography) is preferably about 3,000 to about 50,000 g / mol, about 4,000 to about 40,000 g / mol, about 5,000 to about 30,000 g / mol, or about 6,000 to about 20,000 g / mol.

[0041] The crosslinking modifier compositions used according to some embodiments of the present invention comprise at least one acid- or alkali-generating polymer, as described above, dispersed or dissolved in a solvent system. In some embodiments, the solvent system used in the crosslinking modifier composition has a boiling point of about 70°C to about 200°C, and more preferably about 100°C to about 150°C. Preferred solvent systems for forming the crosslinking modifier compositions include solvents selected from: propylene glycol monomethyl ether acetate (PGMEA), PGME, propylene glycol n-propyl ether (PnP), ethyl lactate (EL), cyclohexanone, γ-butyrolactone (GBL), methyl isobutyl methanol, propylene glycol ethyl ether (PGEE), n-butyl acetate, or mixtures thereof.

[0042] Preferably, the solvent system can be used in an amount of about 95% to about 99.5% by weight, and more preferably about 98% to about 99% by weight, based on the total weight of 100% by weight of the crosslinking modifier composition, with the remainder belonging to the solids in the composition, which are substantially entirely the polymer described above. In the latter case, the polymer can be present in the composition in an amount of about 1% to about 10% by weight, and preferably about 2% to about 5% by weight, based on the total weight of 100% by weight of the composition. In some embodiments, the composition has a total solids content, and the polymer is at least about 99.5% to about 100% of the total solids content, and even more preferably about 100% of the total solids content.

[0043] Suitable compositions can be formed by mixing acid- or alkali-generating polymers with a solvent system under ambient conditions. Meanwhile, any optional components (e.g., surfactants, catalysts, and / or other additives) can be mixed.

[0044] The acid- or alkali-generating polymer in the crosslinking modifier composition can generate a crosslinking modifying component (e.g., an acid or a base) that diffuses into or interacts with the upper layer, thereby interfering with the degree of crosslinking in adjacent layers (e.g., reducing existing crosslinking, or inhibiting or preventing new crosslinking). The specific composition of the crosslinking modifier composition (and the resulting crosslinking modifier layer) can be selected to effectively alter the degree of crosslinking in adjacent layers, as further detailed below.

[0045] 2. The composition of the planarization layer

[0046] The planarization layer composition may comprise at least one crosslinkable polymer dispersed or dissolved in a solvent system. The polymer may be present in amounts of about 0.1% to about 20% by weight, preferably about 0.5% to about 10% by weight, and more preferably about 1% to about 5% by weight, based on the total weight of the composition taken as 100% by weight.

[0047] In some embodiments, the polymer may be selected such that the planarization layer is a carbon-rich layer. As used herein, the term "carbon-rich" means that the layer is formed of a composition comprising about 50 wt% to about 9 wt% carbon, preferably about 70 wt% to about 90 wt% carbon, and more preferably about 75 wt% to about 80 wt% carbon, based on total solids taken as 100 wt% of the composition. The specific polymer used in the carbon-rich layer may vary, but is selected to achieve the carbon content specifically described above. This percentage can be readily calculated by those skilled in the art based on the chemical structure of the solids included in the composition. Alternatively, the carbon atom and total atomic content can be analyzed and calculated using known analytical equipment, including X-ray fluorescence spectroscopy, Auger spectroscopy, and secondary ion mass spectrometry.

[0048] Specific examples of polymers used in carbon-rich planarization compositions (and layers) include, but are not limited to: acid-catalyzed crosslinkable polymers (with or without crosslinking agents), such as epoxy resins (e.g., Epiclon® epoxy resin, epoxy cresol phenolic resin (ECN), commercial spin-coated carbon materials (e.g., OptiStack® SOC110 series materials, Brewer Science, Inc.), polyvinyl alcohol, and 2-hydroxyethyl methacrylate polymers.

[0049] In some embodiments, the planarization layer may comprise at least one polymer having a high silicon content. For example, the polymer may comprise about 25 to about 50% by weight, or about 30 to about 45% by weight, or about 33 to about 40% by weight of silicon, based on a total weight of 100% of the polymer.

[0050] The planarization composition may be a crosslinkable composition and therefore may include at least one crosslinkable polymer. In some embodiments, the polymer used in the planarization composition comprises an acid-crosslinkable (or acid-catalyzed crosslinkable) polymer. Examples include, but are not limited to, polymers comprising repeating monomers having functional groups selected from: epoxy groups, vinyl ethers, hydroxyl groups, carboxylic acids, glycidyl groups, thiols, or combinations thereof. In some embodiments, the polymer used in the planarization composition may comprise a base-crosslinkable (or base-catalyzed crosslinkable) polymer.

[0051] Alternatively, the planarization composition may include at least one polymer that can be decrosslinked (i.e., decrosslinked) by contact with an acid. Examples of such polymers include carboxylic acid-containing polymers having a vinyl ether crosslinking agent. Furthermore, in some embodiments, the polymer used in the planarization composition may include at least one polymer that can be decrosslinked (i.e., decrosslinked) by contact with a alkali.

[0052] In some embodiments, the planarization composition may further comprise a separate crosslinking agent, while in other embodiments, the polymer used in the planarization composition may be self-crosslinkable (e.g., one or more crosslinkable groups may be incorporated into one or more polymers). Suitable crosslinking agents used in practice include those selected from epoxides, melamines, and vinyl ether crosslinking agents, such as MY721 (N,N,N′,N′-tetraglycidyl-4,4′-methylene-diphenylamine), Cymel® 303 (hexamethoxymethylmelamine), Powderlink™ 1174 [1,3,4,6-tetra-(methoxymethyl)glycourea], ECN 1299 (epoxycresol phenolic resin), or Epon SU-8. In embodiments where a separate crosslinking agent is used, the separate crosslinking agent is preferably included in an amount of about 5% to about 40% by weight, and more preferably about 10% to about 30% by weight, based on a total weight of 100% by weight of the composition.

[0053] In some embodiments, a catalyst may be included to initiate the crosslinking reaction. Suitable catalysts include acids or bases and may include one or more selected from: p-toluenesulfonic acid (pTSA), 5-sulfosalicylic acid (5-SSA), triphenylphosphine, bis(triphenylphosphine-1)ammonium chloride, tetrabutylphosphonium bromide, and ethyltriphenylphosphonium acetate, benzyltriethylammonium chloride (BTEAC), and tetramethylammonium hydroxide (TMAH). Specific examples include hot acid generating agents (TAGs), such as TAG2678 and TAG2689 (commercially available from King Industries in Norwalk, Connecticut). Unlike the acid- or base-generating functional groups discussed above with respect to the crosslinking modifier compositions, the catalyst included in the planarization composition (or layer) may not be bound to the polymer itself, but may instead be added separately to promote the crosslinking reaction.

[0054] When a catalyst is used in the planarization composition, the planarization composition preferably includes the catalyst in an amount of about 0.5% to about 5% by weight, and preferably about 1% to about 3% by weight, based on a total weight of 100% by weight of the composition.

[0055] The solvent system used in the planarization composition may comprise solvents selected from PGMEA, PGME, cyclohexane, isopropanol, n-butyl acetate, or combinations thereof. The solvent system may be used in an amount of about 80% by weight to about 99.9% by weight, and more preferably about 95% by weight to about 99% by weight, with the remainder of the composition attributable to solids in the composition, based on a total weight of 100% by weight. The planarization composition may also include a variety of other optional components. Typical optional components include those selected from surfactants, adhesion promoters, or mixtures thereof.

[0056] Regardless of the implementation method, the planarization composition can be formed by simply dispersing or dissolving the polymer as described above with any other components in the solvent system, preferably for a sufficient time under ambient conditions, in order to form a substantially homogeneous dispersion.

[0057] Method using the crosslinking modifier and planarization composition

[0058] refer to Figure 1 (A) schematically depicts a stack 10. The stack 10 includes a substrate 12 having a surface 14.

[0059] Substrate 12 comprises any suitable type of microelectronic substrate, and is preferably a semiconductor substrate. Exemplary substrate types may be selected from: silicon, SiGe, SiO2, Si3N4, SiON, SiCO:H (such as products sold by SVM Corporation in Santa Clara, California under the name Black Diamond), combinations of tetramethylsilicate and tetramethylcyclotetrasiloxane (such as products sold under the name CORAL), aluminum, tungsten, tungsten silicide, gallium arsenide, germanium, tantalum, tantalum nitride, Ti3N4, hafnium, HfO2, ruthenium, indium phosphide, glass, or combinations thereof.

[0060] Prior to processing, an optional intermediate layer (not shown) may be formed on the surface 14 of the substrate 12. Examples of optional intermediate layers include, but are not limited to: silicon, silicon dioxide, silicon carbide, silicon nitride, silicon nitride oxide, metals (including TiN and / or tungsten), carbon (including carbon fibers, carbon nanofibers, carbon nanotubes, diamond, and / or graphene), fluorocarbons, filaments, and high-k dielectrics. One or more of these intermediate layers may be present on the surface 14 of the substrate 12, or none of these intermediate layers may be present on the surface 14 of the substrate 12.

[0061] like Figure 1As described in (A), the substrate 12 has a non-planar surface 14, which includes one or more topographic regions on its surface. As used herein, "topography" refers to the height or depth of a structure within or on the substrate surface 14. Examples of specific topographic features include, but are not limited to, contact holes, via holes, raised features, raised lines, and / or trenches. The topography may be included directly on the substrate surface 14, or it may be included in one or more layers of other material (not shown, such as optional intermediate layers as described above) formed on the substrate surface 14.

[0062] like Figure 1 As shown in (A), the surface 14 of the substrate 12 has a first region (i.e., a “dense region”) 16a with dense morphological features and a second region (i.e., a “isolated region”) 16b with sparse morphological features. As used herein, the term “dense region” in relation to substrate morphology refers to a region on the surface of the substrate (or an intermediate layer formed thereon) with a spacing-to-line ratio (P) of about 4:1 or lower. Preferably, the P of the dense region is in the range of about 0.5:1 to 3.5:1, about 1:1 to about 3:1, or about 1.5:1 to about 2.75:1. Conversely, the term “isolated region” or “isolated region” in relation to surface morphology refers to a region on the surface of the substrate (or an intermediate layer formed thereon) with a P greater than 4:1. The P of the isolated region can be in the range of about 4.5:1 to about 14:1, about 5:1 to about 12:1, or about 6:1 to about 10:1. Figure 1 As shown in (A), the morphological feature density of the dense region 16a is higher than that of the sparse region 16b.

[0063] like Figure 1 As shown by the broken line in (A), the dense and sparse regions 16a,b may be spaced apart from each other at various locations on the substrate surface 14. A single substrate surface 14 (or the upper surface of the topmost intermediate layer, if present) may include a plurality of dense and / or sparse regions spaced apart on the entire surface 14 of the substrate 12.

[0064] Now turning Figure 1(B) The crosslinking modifier composition can be applied to and treated on the surface 14 of the substrate 12 (or the uppermost surface of the topmost intermediate layer, if present) to form a crosslinking modifier layer 18. The crosslinking modifier composition can be applied by any known method, preferably spin coating. When spin coating is used, the ramp speed can preferably be from about 500 to about 15,000 rpm / s, and more preferably from about 1,000 to about 12,000 rpm / s, the rotation speed can preferably be from about 500 rpm to about 5,000 rpm, and more preferably from about 1,000 to about 1,750 rpm, the duration is preferably from about 30 seconds to about 120 seconds, or more preferably from about 45 seconds to about 75 seconds, followed by baking. Preferred baking conditions include heating at a temperature preferably about 100°C to about 300°C, more preferably about 130°C to about 250°C, even more preferably about 150°C to about 215°C, or most preferably about 160°C to about 205°C for a period of time preferably about 30 seconds to about 300 seconds, or more preferably about 45 seconds to about 75 seconds, to form a crosslinking modifier layer 18.

[0065] Optionally, a solvent can be used to wash the crosslinking modifier layer 18 to remove any unbound polymer residues. Suitable washing solvents include, for example, polar solvents such as PGMEA, PGME, methyl isobutyl ketone (MIBK), cyclohexanone, ethyl lactate, dimethylacetamide, and / or tetrahydrofurfuryl alcohol. The solvent washing step can be performed using a stirring or dynamic washing method. When stirring is used, it can be carried out for a period of preferably about 10 seconds to about 120 seconds, and more preferably about 15 seconds to about 90 seconds.

[0066] Residual solvent is removed by an optional rotational step followed by a drying step. The rotational drying step is preferably performed at a speed of about 100 rpm to about 3,000 rpm, and more preferably about 1,250 rpm to about 1,750 rpm, for a period of about 30 seconds to about 120 seconds, and more preferably about 45 seconds to about 75 seconds. Preferred drying conditions for the drying step may involve a temperature of about 90°C to about 200°C, and more preferably about 150°C to about 210°C, for a period of about 30 seconds to about 120 seconds, and preferably about 45 seconds to about 75 seconds.

[0067] The crosslinking modifier layer 18 may have a substantially uniform thickness across the entire surface 14 of the substrate 12 (or the uppermost surface of the top intermediate layer, if present). The average thickness of the crosslinking modifier layer 18 may be in the range of about 1 nm to about 10 nm, or preferably about 2 nm to about 8 nm. Figure 1(B) As generally shown, the crosslinking modifier layer 18 can have a high degree of conformability with the surface 14 of the substrate 12 (or the uppermost surface of the top intermediate layer, if present). Exact conformability is not required, as long as the overall density of the crosslinking modifier applied in each dense and sparse region 16a,b is correlated with the morphological density in that region. Generally, dense regions 16a have a larger surface area (due to fluctuating morphology), resulting in a higher density of crosslinking modifier in these regions compared to sparse regions 16b, which have a smaller surface area and thus a lower density of crosslinking modifier.

[0068] In some embodiments, the crosslinking modifier layer 18 may have a low total thickness variation (TTV), meaning that the thinnest and thickest points of layer 18 are not significantly different from each other. Preferably, the TTV of a given layer is calculated by measuring the thickness at a certain number of points or locations on the layer (preferably at least about 50 points, or about 50 points, more preferably at least about 100 points, or about 100 points, and even more preferably at least about 1,000 points, or about 1,000 points). The difference between the highest and lowest thickness measurements measured at these points represents the TTV measurement result for that layer. In some TTV measurement cases, edge exclusion or outliers may be removed from the calculation. In those cases, the number of measurements accepted is expressed as a percentage; that is, if the TTV is given with 97% acceptance, the highest and lowest 3% of measurements are excluded, where the 3% is evenly divided between the highest and lowest (i.e., 1.5% each). Preferably, the aforementioned TTV range is achieved using approximately 95% to approximately 100% of the measurement values, more preferably approximately 97% to approximately 100% of the measurement values, and even more preferably approximately 100% of the measurement values.

[0069] In addition to having a low TTV in absolute terms (e.g., 5 pm), the TTV relative to the average film thickness of the crosslinking modifier layer 18 should also be low. Therefore, the TTV of the crosslinking modifier layer 18 on the blank substrate should be less than about 25% of the average thickness, preferably less than about 10% of the average thickness, and more preferably less than about 5% of the average thickness of the bonding layer 20. For example, if the average thickness of the crosslinking modifier layer 18 is 50 μm, the maximum acceptable TTV will be about 12.5 μm or less (less than about 25% of 50 μm), preferably about 5 pm or less (less than about 10% of 50 μm), and more preferably about 2.5 μm or less (less than 5% of 50 μm).

[0070] Now turning Figure 1(C) The planarization composition formulated as previously described is coated onto the crosslinking modifier layer 18 to form a planarization layer 20. The planarization composition can be applied using any known method, including spin coating. When spin coating is used, the planarization composition can be applied at a speed preferably ranging from about 500 to about 15,000 rpm / s, and more preferably from about 750 to about 8,000 rpm / s, and at a rotational speed preferably from about 500 rpm to about 5,000 rpm, and more preferably from about 1,000 to about 1,750 rpm, for a period of preferably about 30 seconds to about 120 seconds, and more preferably from about 45 seconds to about 75 seconds, followed by baking. Preferred baking conditions include heating via a hot plate at a temperature of about 100°C to about 300°C, more preferably about 130°C to about 250°C, even more preferably about 150°C to about 215°C, and most preferably about 160°C to about 205°C for a period of about 30 seconds to about 300 seconds, and more preferably about 45 seconds to about 75 seconds, to obtain the planarization layer 20. The baking step also activates any catalyst present in the planarization composition, which promotes crosslinking of the planarization layer 20. This can be particularly useful when the crosslinking modifier layer 18 comprises photo-generating alkali or acid-generating groups. Depending on the embodiment in which the crosslinking modifier layer 18 comprises photo-generating alkali or acid-generating groups, an additional radiation exposure step may be included to activate the photo-generating acid or alkali within the crosslinking modifier layer 18.

[0071] like Figure 1 As shown in (C), when applied to surface 14 of substrate 12 (or the uppermost surface of the top intermediate layer, if present), the planarizing composition tends to accumulate more in the denser regions 16a of the morphological features compared to in the sparser regions 16b. This may be partly due to the flow properties of the planarizing composition and the substrate morphology, as more planarizing composition is needed to fill the sparser regions (e.g., region 16b) to achieve a given layer thickness compared to filling the denser regions (e.g., region 16a).

[0072] like Figure 1 As shown in (C), the thickness of the planarization layer 20 is non-uniform due to the different accumulation of planarization material in the dense and sparse regions 16a,b. Therefore, a deviation B develops between the two regions 16a, 16b. As used herein, and unless otherwise stated, the term "deviation" refers to the difference in average layer thickness between the dense region 16a and the sparse region 16b of the substrate. Typically, this deviation can be in the range of about 35 nm to about 70 nm, or about 40 nm to about 60 nm, using conventional global planarization materials and methods.

[0073] The average layer thickness at the time of deviation was obtained by measuring (using SEM images and imaging programs such as ImageJ) the layer thickness at a point approximately halfway between two uninterrupted features whose boundaries are within approximately 1,000 nm of each other. These measurements were repeated up to 49 times on the wafer (or other regions defined herein), and the average results were taken to determine the average layer thickness. The deviation was then calculated by taking the average layer thickness over the dense region (…). Figure 1 (C) to (D) 16a) from the average thickness of the same layer in the evacuation zone Figure 1 Subtract from 16b) in (C) to (D). Note that a negative deviation in this case indicates that the layer thickness in the sparse region is greater than that in the dense region.

[0074] According to some embodiments, the specific composition of the crosslinking modifier layer 18 and the planarization layer 20 may be selected such that after the crosslinking modified component is generated within the crosslinking modifier layer 18, the crosslinking modified component can contact at least a portion of the upper planarization layer 20, such that the crosslinking modified component can intervene (e.g., reduce or prevent) crosslinking within at least a portion of the planarization layer 20. In some embodiments, at least a portion of the crosslinking modified component from the crosslinking modifier layer 18 can diffuse into at least a portion of the planarization layer 20, wherein the crosslinking modified component can react with at least a portion of the crosslinked polymer, or react with a crosslinking agent or group present in that portion of the planarization layer 20. In other embodiments, a crosslinking agent from the upper planarization layer 20 can diffuse into the crosslinking modifier layer 18 and react with the crosslinking modified component in that layer 18, thereby reducing the amount of crosslinking agent present in the planarization layer 20. In either case, if the crosslinking modifier component is not generated or is present in the crosslinking modifier layer 18, the generation or presence of the crosslinking modifier component in the crosslinking modifier layer 18 reduces the degree of crosslinking in at least a portion of the planarization layer 20 compared to the degree of crosslinking that would otherwise exist.

[0075] According to some embodiments, when the crosslinking modifying component from the crosslinking modifier layer 18 diffuses into at least a portion of the planarization layer 20, the crosslinking modifying component can react with at least a portion of the crosslinking agent or groups or the crosslinked polymer present in that portion of the planarization layer 20. For example, if the planarization layer 20 comprises an acidic crosslinking agent and an acid-crosslinkable (acid-catalyzed crosslinking) polymer, a base or base-containing compound can be used as the crosslinking modifying component and can diffuse into the planarization layer 20 to react (neutralize) with a portion of the acidic crosslinking agent therein. Therefore, the degree of crosslinking in that portion of the planarization layer 20 is less than the degree of crosslinking that would have been present in that portion if the crosslinking modifying component were not present in the crosslinking modifier layer 18. Similarly, if the planarization layer 20 comprises an alkaline crosslinking agent and an alkaline-crosslinkable (alkaline-catalyzed crosslinking) polymer, an acid or acid-containing compound can be used as the crosslinking modifying component. When the planarization layer 20 does not include a separate crosslinking agent but instead includes acid-crosslinkable or alkali-crosslinkable groups in the polymer itself, a similar acid / alkali composition scheme can be used in the crosslinking modifier layer 18 and the planarization layer 20.

[0076] Alternatively, in some embodiments, the crosslinking modifying component from the crosslinking modifier layer 18 may diffuse into the planarization layer 20 and may decrosslink at least some of the crosslinked polymers present in the planarization layer 20. As described above, the crosslinking modifying component may be selected to achieve a reduction in the degree of crosslinking in the planarization layer 20. For example, when the crosslinked polymer is acid-decrosslinkable, the crosslinking modifying component may be an acid or an acid-containing compound. When the crosslinked polymer is alkali-decrosslinkable, the crosslinking modifying component may be an alkali or an alkali-containing compound. Therefore, when the crosslinking modifying component contacts or diffuses into at least a portion of the planarization layer, it may decrosslink at least some of the crosslinked polymers in that portion.

[0077] In other embodiments, at least a portion of the crosslinking agent present in the planarization layer 20 may contact or diffuse into a portion of the crosslinking modifier layer 18, wherein it may react with (e.g., be neutralized by) at least a portion of the crosslinking modifier component present in the layer 18. In this embodiment, this reduces the total amount of crosslinking agent present in at least a portion of the planarization layer 20, which reduces the degree of crosslinking in that portion of the layer 20. Similar to other embodiments, the crosslinking modifier may be selected based on the type of crosslinking agent used in the planarization layer 20 (or vice versa), such that an alkaline or alkaline crosslinking modifier component may be used in the crosslinking modifier layer 18 to neutralize acidic crosslinking agents from the planarization layer 20, and an acidic or acid-containing crosslinking modifier component may be used in the layer 18 to neutralize alkaline crosslinking agents present in the planarization layer 20.

[0078] With regard to the neutralization of the crosslinking agent in planarization layer 20 by the crosslinking modifier layer 18, and / or with regard to the decomposition of the crosslinked polymer in planarization layer 20 by the crosslinking modifier layer, planarization layer 20 ultimately has a low degree of crosslinking (or even no crosslinking). In some embodiments, this may occur only at or near the boundary between planarization layer 20 and crosslinking modifier layer 18 when, for example, the diffusion of components from one layer to other layers is restricted. This reduction in crosslinking can be more pronounced in regions of higher morphological density (e.g., dense regions), where the layer thickness (and thus the concentration of crosslinking agent in planarization layer 20 and / or crosslinking modifier layer 18) is greater than the layer thickness in regions of lower morphological density (e.g., sparse regions).

[0079] Therefore, compared to the portion of planarization layer 20 on the loose region 16b, the portion of planarization layer 20 on the dense region 16a of the substrate 10 undergoes less crosslinking (i.e., crosslinking is more suppressed). This is at least in part due to the larger volume of the crosslinking modifier component present in the crosslinking modifier layer 18 in the dense region 16a compared to the loose region 16b (and / or, in some cases, the larger volume of the crosslinking agent present in the planarization layer 20). This is also at least in part due to the increased surface area of ​​the interface between the crosslinking modifier layer 18 and the planarization layer 20 in the dense region 16a (due to its fluctuating morphology) compared to the loose region 16b (which has a flatter morphology). Therefore, after baking, the dense region 16a has a higher volume of uncrosslinked material in the planarization layer 20 above it compared to the portion of planarization layer 20 above the loose region 16b.

[0080] In some embodiments, a solvent may be used to remove (or develop back) a portion of the planarization layer 20, thereby reducing its thickness. The development back step can be performed by applying a solvent to the planarization layer 20. Suitable solvents include, but are not limited to, PGMEA, PGME, MIBK, cyclohexanone, ethyl lactate, and combinations thereof. In some cases, the solvent may be the same as the solvent used to form the planarization composition. The solvent can be applied by any known method, including puddle. When puddle is used, it can be performed for a period of preferably about 5 seconds to about 100 seconds, and more preferably about 10 seconds to about 60 seconds, followed by drying at a temperature of about 90°C to 215°C, more preferably about 100°C to about 185°C, or even more preferably about 150°C to about 170°C. This drying can be performed for a period of preferably about 30 seconds to about 120 seconds, and more preferably about 45 seconds to about 75 seconds. If desired, the puddle step can be repeated before the drying step.

[0081] Furthermore, since the degree of crosslinking in the planarization layer 20 is lower than that in the dense region 16a of the substrate 12, the development retreat step removes more planarization material from the planarization layer 20 in the dense region 16a compared to the planarization layer 20 on the sparse region 16b. This means that the average thickness of the dense region 16a is reduced more significantly compared to the average thickness of the sparse region 16b, which reduces or eliminates the deviation between the two regions. In some embodiments, after the development retreat step, the deviation B in the planarization layer 20 is less than about 30 nm, less than about 25 nm, less than about 20 nm, or less than about 10 nm. In some cases, this deviation can be completely removed (e.g., 0 nm), such as... Figure 1 As shown in (D). Therefore, the stack 10 requires no further processing or additional development back-off steps, and achieves global planarization of the substrate.

[0082] In some embodiments, after the development rollback step, the planarization layer 20 substantially does not include regions of uncrosslinked polymer. That is, in some embodiments, at least about 90%, at least about 95%, at least about 99%, or all of the total volume of the planarization layer 20 is crosslinked. This is in contrast to other types of potential overlying layers (e.g., photoresist), which can be photopatterned and therefore have both crosslinked and uncrosslinked regions (before development). In some embodiments, the planarization layer covers at least about 90%, at least about 95%, or at least about 99% of the surface of the substrate 12 (or the layer disposed thereon) and has not undergone photopatterning. Instead, the planarization layer 20 can serve as a base layer for one or more overlying photoresist layers (not shown) and can itself be photopatterned.

[0083] For reference Figure 2 (A) to (E) show the relationship with Figure 1 The methods described in (A) to 1(D) are similar global flattening methods, with the same reference numerals indicating the same components. Figure 2 The methods shown in (A) to 2(C) are the same as Figure 1 The methods described in (A) to 1(C) are the same.

[0084] exist Figure 2 In some embodiments shown in (D), the development retreat step may remove all or almost all (not shown) of the planarization layer from the dense region 16a of the topographic figure. For example... Figure 2 As shown in (D), the crosslinking modifier layer 18 can be retained prior to subsequent processing steps, or can be reapplied subsequently if necessary. Figure 2As shown in (D), a portion of the planarization layer 20 remains in the sparse region 16b, therefore the thickness of the planarization layer 20 in the sparse region 16b is greater than the thickness of the planarization layer 20 in the dense region 16a. Consequently, a negative deviation of the planarization material is generated in the planarization layer 20.

[0085] Subsequently, as Figure 2 As shown in (E), a second amount of planarizing composition can be applied to the dense region 16a and the sparse region 16b in a manner similar to that described above, to obtain a second planarization layer 22. The second planarization composition can be applied to the upper surface of the layer while some of the first planarization material remains in the dense region 16a. The second planarization composition is applied to the surface 14 of the substrate 12 (or the uppermost surface of the top intermediate layer, if present) when all the first planarization material is removed from the dense region 16a. The second planarization composition is applied to the surface of the remaining planarization layer 20 in the sparse region 16b. The second planarization composition may be the same as or different from the first planarization composition used to form the planarization layer 20. Once the second composition is applied, it can be baked and subsequently developed back in a similar manner, as described above, to obtain a final second planarization layer 22 with little or no deviation, as... Figure 2 As shown in (E).

[0086] Although repeating this additional planarization step once or multiple times on the second planarization layer 22 is within the scope of this technique, it has been found that in most applications, further planarization and development rollback steps are unnecessary. Therefore, the method according to this technique is generally more time- and cost-efficient compared to conventional global planarization methods.

[0087] In some embodiments, the amount of deviation that occurs when the planarizing composition is applied (and / or the amount of negative deviation after the development retreat step due to the amount of planarizing material remaining in the sparse area compared to the amount of planarizing material remaining in the dense area) can be adjusted by adjusting the composition of the crosslinking modifier composition and / or the properties of the crosslinking modifier layer 18. Examples of variables that can be adjusted to control the thickness and deviation of the planarizing layer 20 include, but are not limited to: the amount of crosslinking modifier present in the crosslinking modifier layer 18, the thickness of the crosslinking modifier layer 18 and / or the planarizing layer 20, the crosslinking dosage present in the planarizing material and / or the degree of crosslinking achievable by the planarizing material, and / or the specific baking conditions of one or both of the crosslinking modifier layer 18 and / or the planarizing layer 20.

[0088] It is worth noting that all of the above can be achieved by a single coating step followed by a single baking step. That is, in some embodiments, the additional coating or baking steps typically performed in prior art processes are unnecessary, or the use of multiple planarization layers used in prior art processes is unnecessary. Furthermore, the additional development rollback steps or polishing (such as CMP) steps required in prior art processes are unnecessary. Therefore, these additional steps / processes are preferably avoided, resulting in a cheaper and significantly simplified global planarization process.

[0089] Regardless of whether a single-layer or double-layer planarization method is used, the planarized layer in the resulting stack can be used for additional photolithography processes. For example, in some embodiments, a photoresist layer can be applied directly to the uniform planarization layer, wherein the photoresist layer is patterned according to conventional processes (e.g., exposure to photochemical radiation at a target wavelength and development of the exposed photoresist). Alternatively, the material can be used as the underlayer (e.g., SOC) material in a three-layer lithography process, where a silicon hard mask serves as the intermediate layer and the photoresist serves as the top layer.

[0090] According to some embodiments of this technology, the compositions described herein can be used for global planarization applications, which are in some respects more challenging than local planarization applications. As used herein, the term "local planarization" refers to planarizing a single feature or a relatively small group of features on a given surface, while "global planarization" refers to planarizing an entire surface (e.g., a substrate or one or more intermediate layers thereon). In some embodiments, global planarization can be performed on two or more different types of features, while local planarization can be performed on a region of a substrate or surface that includes a single type of feature.

[0091] Other advantages of the various implementations will become apparent to those skilled in the art after reviewing the disclosure herein and the following working examples. It should be understood that, unless otherwise indicated herein, the various implementations described herein are not necessarily mutually exclusive. For example, features described or depicted in some implementations may be included in, but not necessarily included in, other implementations. Therefore, this disclosure covers various combinations and / or integrations of the particular implementations described herein.

[0092] As used herein, when the phrase “and / or” is used to list two or more items, it indicates that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing or not containing components A, B and / or C, then the composition may contain or not contain: A only; B only; C only; 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.

[0093] This specification also uses numerical ranges to quantify certain parameters relating to various embodiments. It should be understood that when a numerical range is provided, the range should be interpreted as providing written support for claims that specify only the lower limit of the range and claims that specify only the upper limit of the range. For example, the disclosed numerical range of about 10 to about 100 provides written support for claims specifying "greater than about 10" (no upper limit) and claims specifying "less than about 100" (no lower limit).

[0094] Example

[0095] The following embodiments illustrate methods according to this disclosure. However, it should be understood that these embodiments are provided by way of illustration and nothing therein should be construed as limiting the overall scope.

[0096] Example 1

[0097] Synthetic crosslinking modifier 1

[0098] In this embodiment, the basic polymer crosslinking modifier (crosslinking modifier 1) was formed by adding 0.63 g of 4-vinylpyridine (Sigma-Aldrich, St Louis, MO), 4.81 g of methyl methacrylate (Monomer Polymer & Dajac Labs, Ambler, PA), 0.78 g of 2-hydroxyethyl methacrylate (TCI Chemicals, Portland, OR), 0.148 g of 2,2′-azobis(2-methylpropionitrile) (Sigma-Aldrich, St Louis, MO), and 18.65 g of PGMEA as a solvent (Fujifilm Ultra Pure Solutions, Inc., Carrollton, TX). The contents of the flask were then sparged with nitrogen for 10 minutes, followed by heating at 75°C for 24 hours. The reaction mixture was then cooled, diluted with acetone, and precipitated into approximately 500 mL of hexane. The resulting solid was collected by vacuum absorption and dried overnight at 40°C under vacuum.

[0099] Example 2

[0100] Synthetic crosslinking modifier 2

[0101] In this embodiment, another basic polymer crosslinking modifier (crosslinking modifier 2) is formed by adding 0.168 g of 4-vinylpyridine (Sigma-Aldrich, St Louis, MO), 7.05 g of methyl methacrylate (Monomer Polymer & Dajac Labs, Ambler, PA), 1.04 g of 2-hydroxyethyl methacrylate (TCIChemicals, Portland, OR), 0.197 g of 2,2′-azobis(2-methylpropionitrile) (Sigma-Aldrich, St Louis, MO), and 24.77 g of PGMEA solvent (Fujifilm Ultra Pure Solutions, Inc., Carrollton, TX) to a round-bottom flask. ) The contents of the flask were then sparged with nitrogen for 10 minutes, followed by heating at 75°C for 24 hours. The reaction mixture was cooled to room temperature and collected as a mother liquor.

[0102] Example 3

[0103] Application of crosslinking modifier layer and planarization layer thickness control

[0104] The crosslinking modifier 1 synthesized in Example 1 was dissolved in PGMEA to obtain a 1.0 wt% solution, which was filtered through a 0.1-mm PTFE filter. The resulting crosslinking modifier composition was applied to two different silicon wafers (wafer A and wafer B) by spin coating at a variable speed of 1000 rpm / s, followed by spin coating at 500 rpm for 60 seconds, and then spin coating at 1500 rpm for 30 seconds. A third wafer (wafer C) was not coated and served as a control. The coated wafers A and B were baked at 160°C for 60 seconds, followed by rinsing twice with PGMEA for 20 seconds each time by stirring. Wafer A was then heated to 160°C for 60 seconds, and wafer B was heated to 205°C for 60 seconds to form a crosslinking modifier layer on each substrate. The final thickness of the crosslinking modifier layer on wafer A (heated to 160°C) is 4.4 mm, while the final thickness of the crosslinking modifier layer on wafer B (heated to 205°C) is 7.6 mm.

[0105] Subsequently, a planarization composition comprising 2.0 wt% epoxy cresol cresol (“ECN”) resin and TAG2678 (TAG:ECN ratio of 0.03:1) in PGMEA was filtered through a 0.1-mm PTFE filter. The resulting planarization composition was applied to all three wafers (wafers A to C) as follows: spin-coating at a variable speed of 1000 rpm / s, followed by spin-coating at 500 rpm for 60 seconds, then spin-coating at 1500 rpm for 30 seconds, and baking at 160°C for 60 seconds. The resulting planarization layer was rinsed twice with PGMEA by stirring, 20 seconds each time, and baked at 160°C for 60 seconds.

[0106] The planarization layer thickness was measured before and after washing. Wafer A lost 6.6 nm of planarization layer thickness, while wafer B experienced a 76.5 nm reduction. Under the same conditions, control wafer C lost only 0.2 nm of planarization material. These results are summarized in Tables 1a and 1b below.

[0107]

[0108] Example 4

[0109] Global planarization using crosslinking modifier layers

[0110] In this experiment, the following were used: Figure 4 The chip is shown in the lower left (photograph image) and lower right (enlarged plan view). Figure 4 The upper left and upper right portions provide cross-sectional SEM images, showing dense morphological feature regions (line to spacing ratio of 50:100, or P = 2:1) and sparse morphological feature regions (line to spacing ratio of 100:500, or P = 5:1), respectively.

[0111] According to the process described in Example 3, a crosslinking modifier layer is applied to both the dense and sparse regions of the wafer. The wafer is then rinsed with PGMEA (twice, 20 seconds each) by stirring, rotary dried at 1500 rpm for 60 seconds, and then baked at 160°C for 60 seconds to form the crosslinking modifier layer. Subsequently, a planarizing material is applied to each substrate described in Example 3, followed by washing with PGMEA (twice by stirring, 20 seconds each), rotary dried at 1500 rpm for 60 seconds, and baked at 160°C for 60 seconds.

[0112] Figure 5The images show SEM cross-sections of dense and sparse morphology regions of the substrate at different points during the aforementioned processes. Specifically, the top image (Image 1) shows the initial state of the wafer, while subsequent images (Image 2) show the wafer after baking with a conformal crosslinking modifier layer. The crosslinking modifier layer in Image 2 is approximately 4 nm thick and is not visible. Image 3 shows the wafer after the application of planarization material, but before any planarization step. Therefore, the coating on the dense region (left) is thicker than the coating on the semi-dense (sparse) region (right). In other words, a gap-filling deviation occurs. Image 4 shows the wafer after a development rollback step (e.g., washing the planarization layer with a solvent). As shown in Image 4, more gap-filling material has been removed from the dense region compared to the semi-dense (sparse) region, resulting in a reverse gap-filling deviation (e.g., more planarization material has been removed from the dense region compared to the sparse region). The coated substrate in Image 4 is now ready for the application of an additional planarization layer to reduce the reverse deviation between the dense and sparse regions, as shown in Image 4. Figure 5 Image 4 is shown. Another example shows that dense areas can be planarized when an additional gap-filling coating is applied, as shown in Example 5 below.

[0113] Example 5

[0114] Global flattening using the develop backstep step

[0115] Three silicon wafers, each exhibiting both dense and sparse morphological features, were coated with a crosslinking modifier layer, as described in Example 4. Another similar wafer was not coated with the crosslinking modifier. Subsequently, all wafers were coated with planarization compositions formulated using varying amounts of ECN to achieve different thicknesses. All planarization compositions included TAG2678 at a ratio of 0.02:1 to ECN and included PGMEA as a solvent. The planarization compositions were applied to each wafer via spin coating at a variable speed of 1000 rpm / s, followed by spin coating at 500 rpm for 60 seconds, then at 1500 rpm for 60 seconds, and baked at 160°C for 60 seconds. The planarization layer was then rinsed with PGMEA (rinsed twice, 20 seconds each time, via stirring), spin-dried at 1500 rpm for 60 seconds, and baked at 160°C for 60 seconds. Figure 6 The image provides SEM cross-sections of each coated wafer, with the substrate number located in the upper left corner of each image. Deviations were calculated, and the results are summarized in Table 2 below.

[0116] Table 2

[0117] like Figure 6As shown, the positive deviation in substrate 4 (control) is a result of more planarization material accumulation in the dense regions of the wafer. Without the use of a crosslinking modifier layer, the development backstep has virtually no effect on the planarization layer of substrate 4. Conversely, each of substrates 1-3 (disclosed) includes a crosslinking modifier layer located beneath the planarization layer, which removes the positive deviation during the development backstep. The negative deviation in each of substrates 1-3 indicates that the deviation reduction step was slightly excessive, resulting in a slightly thicker planarization layer in the sparse regions of the wafer.

[0118] Example 6

[0119] Double-layer planarization using different baking temperatures

[0120] Five additional silicon wafers with dense and sparse morphological regions were coated using the crosslinking modifier layer and the first planarization layer described in Example 5. This planarization layer also underwent a development retreat (washing) step, as described in Example 5. A second planarization composition (comprising 3% ECN and TAG2678 in PGMEA, with a TAG:ECN ratio of 0.03:1) was filtered through a 0.1-µm PTFE filter and applied on top of the first planarization layer under the same spin-coating conditions as the first planarization layer. The second planarization layer was also rinsed with PGMEA (after stirring, rinsed twice, 20 seconds each time), then spin-coated and dried at 1500 rpm for 60 seconds, and baked at 205°C for 60 seconds. For each substrate, the deviation between the dense and sparse regions of the second planarization layer was measured. The results are summarized in Table 3 below. Figure 7 The SEM cross-sections of each wafer are provided.

[0121] Table 3

[0122] Example 7

[0123] Two-layer planarization using spin-coated carbon (SOC)

[0124] The crosslinking modifier 2 synthesized in Example 2 was dissolved in PGMEA to obtain a 2.0 wt% solution, which was filtered through a 0.2-mm PTFE filter. The resulting crosslinking modifier composition was applied to two silicon wafers, each having a dense and a sparse morphology region, as described in Example 3. Subsequently, OptiStack was spin-coated at 1500 rpm for 60 seconds. ®A layer of SOC110E-311 (SOC material (commercially available from Brewer Science Inc.)) was applied to the upper surface of the crosslinking modifier layer and baked at 205°C for 60 seconds. The resulting planarization layer had a thickness of 110 nm. After baking, the planarization layer was washed with PGMEA, as described previously in Example 3, except that this layer was baked at 155°C instead of 160°C for 60 seconds.

[0125] According to the process described in Example 6, a second layer of the same SOC planarization composition is applied to one of the wafers, except that baking is performed at 205°C for 60 seconds. The other wafer is further coated with a second SOC planarization layer. Figure 8 SEM cross-sectional images of the wafer with (below) and without (above) the second planarization layer are provided.

[0126] Example 8

[0127] Single-layer planarization using SOC

[0128] A silicon wafer with dense and sparse morphological regions was coated with a crosslinking modifier layer and a first layer of SOC planarization material, as described in Example 7. The thickness of the first planarization layer was 170 nm. After the initial baking step, the planarization layer was washed with PGMEA by stirring (washed twice, 20 seconds each time), followed by baking at 160°C for 120 seconds. A control wafer with similar morphological regions was coated with the SOC planarization material at a speed of only 1000 rpm / s, followed by coating at 1500 rpm for 60 seconds, and then baking at 205°C for 160 seconds. Figure 9 The document provides SEM cross-sectional images, with the disclosed wafer image at the top and the reference wafer image at the bottom.

[0129] Example 9

[0130] Develop equations for predicting layer thickness and bias

[0131] The following equations (1) and (2) are used to predict deviations caused by the application of planarization material to certain substrates. These equations assume that the total amount of planarization material is the same in any given region of the substrate and that there is no long-range material flow (local only): (Equation 1) (Equation 2), Where H is the line height, W is the line width, and P is the spacing per line, such as... Figure 3aThe figure is roughly shown in the figure. As used herein, the term “surface ratio” refers to the total surface area of ​​a given region divided by its open area. Furthermore, the above equations (1) and (2) assume that the deviation originates from the lines occupying the space and may not apply to other types of morphological features.

[0132] Table 4 below summarizes the calculated and measured deviations of several different morphological regions compared to a completely open region, such as... Figure 3b As shown in the image.

[0133] Table 4

Claims

1. A method for forming a structure, the method comprising: A substrate is provided, the substrate comprising a substrate surface; Optionally, one or more intermediate layers are formed on the surface of the substrate, wherein the surface of the substrate, or if the one or more intermediate layers are present, the uppermost surface of the top intermediate layer on the surface of the substrate includes a first region of dense morphological features and a second region of sparse morphological features. A crosslinking modifier composition is applied to the surface of the substrate, or, if present, to the uppermost surface of the top intermediate layer, to form a crosslinking modifier layer, the crosslinking modifier layer covering at least a portion of the first region of the dense morphological feature and at least a portion of the second region of the sparse morphological feature; A planarization composition is applied to the crosslinking modifier layer; Heating the planarization composition forms a planarization layer having a first average thickness in a first region of the dense morphological features and a second average thickness in a second region of the sparse morphological features; and The planarization layer is brought into contact with the solvent, thereby reducing the first average thickness and the second average thickness, wherein the contact reduces the first average thickness more than the second average thickness.

2. The method of claim 1, wherein the crosslinking modifier composition comprises a polymer dispersed or dissolved in a solvent system, the polymer being present in the crosslinking modifier composition in an amount of about 1% to about 10%, based on the total weight of 100% of the crosslinking modifier composition.

3. The method of claim 1 or 2, wherein the planarizing composition comprises an acid-crosslinkable polymer, and the crosslinking modifier composition comprises at least one alkali-generating polymer.

4. The method of claim 3, wherein the alkali-producing polymer comprises about 1.5% by weight to about 12.5% ​​by weight of alkali-producing monomer, based on the total weight of the polymer taken as 100%.

5. The method of claim 3 or 4, wherein the alkali-generating polymer comprises about 5% to about 15% by weight of a surface adhesion monomer, based on the total weight of 100% of the polymer.

6. The method of any one of claims 3 to 5, wherein the alkali-generating polymer comprises about 70% to about 90% by weight of a solubility-enhancing monomer, based on the total weight of 100% of the polymer.

7. The method of any one of claims 3 to 6, wherein the alkali-generating polymer is formed from repeating monomers of 2-hydroxyethyl methacrylate, 4-vinylpyridine, and methyl methacrylate.

8. The method of any one of claims 1 to 7, wherein the method further comprises: The crosslinking modifier composition is heated after application to form the crosslinking modifier layer, wherein the heating is performed at a temperature of about 150°C to about 215°C for a period of about 45 to about 75 seconds.

9. The method of any one of claims 1 to 8, wherein the planarization composition comprises a spin-coated carbon composition.

10. The method of any one of claims 1 to 9, wherein after the heating and before the contact, the deviation of the planarization layer measured between the first region of the dense morphological feature and the second region of the sparse morphological feature is at least 35 nm.

11. The method of claim 10, wherein after the contact, the deviation of the planarization layer measured between the first region of the dense morphological feature and the second region of the sparse morphological feature is no greater than 10 nm.

12. The method of claim 1, further comprising: After the contact, a second planarization composition is applied to the upper surface of the planarization layer in the second region, and to the surface of the substrate, the uppermost intermediate layer if present, and / or the planarization layer if present. The second planarization composition is heated to form a second planarization layer; and the second planarization layer is contacted with a solvent, wherein after the contact, the deviation of the second planarization layer between the first region of the dense morphological features and the second region of the sparse morphological features is less than about 10 nm.

13. The method of claim 12, wherein the second planarizing composition is different from the planarizing composition applied to the crosslinking modifier layer.

14. A method for forming a structure, the method comprising: Optionally, one or more intermediate layers are formed on the surface of a substrate, wherein the surface of the substrate, or if the one or more intermediate layers are present, the uppermost surface of the top intermediate layer on the surface of the substrate includes a first region of dense morphological features and a second region of sparse morphological features. A crosslinking modifier layer is formed on the surface of the substrate, or on the uppermost surface of the top intermediate layer if the top intermediate layer is present, wherein the crosslinking modifier layer is: At least a portion of the first region covering the dense morphological features and at least a portion of the second region covering the sparse morphological features; and It contains at least one polymer capable of generating a crosslinking modified component; A planarization composition is applied to the crosslinking modifier layer, the planarization composition comprising one or both of a crosslinkable polymer or a decrosslinkable polymer; and The planarization composition is heated to form a planarization layer on the crosslinking modifier layer, wherein during the heating, a crosslinking modified component is formed within the crosslinking modifier layer, and at least some of the crosslinking modified components contact the planarization layer during and / or after the heating, wherein the crosslinking modified components in contact with the planarization layer are: (1) Reducing the degree of crosslinking of the crosslinkable polymer, which is the crosslinking that the crosslinkable polymer would undergo during the heating if the crosslinking modifier component is not generated in the crosslinking modifier layer; and / or (2) Decrosslinking at least some of the decrosslinkable polymers in the planarization layer.

15. The method of claim 14, wherein the planarization layer has a first average thickness in a first region of the dense morphological feature and a second average thickness in a second region of the sparse morphological feature, the method further comprising: The planarization layer is brought into contact with the solvent, thereby reducing the first average thickness and the second average thickness, wherein the first average thickness is reduced more than the second average thickness.

16. The method of claim 15, wherein after the contact, the deviation of the planarization layer measured between the first region of the dense morphological feature and the second region of the sparse morphological feature is no greater than 30 nm.

17. The method of any one of claims 14 to 16, wherein the crosslinking modifier comprises an alkali, and the crosslinking modifier reduces the degree of crosslinking of the crosslinkable polymer, which would otherwise have been experienced by the crosslinkable polymer during the heating if the crosslinking modifier were not present in the crosslinking modifier layer.

18. The method of any one of claims 14 to 17, wherein the polymer capable of generating the crosslinking modified component comprises an alkali-forming polymer.

19. The method of claim 18, wherein the alkali-generating monomer comprises a monomer having at least one alkali-generating group bonded thereto, and wherein the alkali-generating group is selected from one or more of the following: aliphatic amines, aromatic amines, heterocyclic amines, or mixtures thereof.

20. The method of any one of claims 14 to 17, wherein the crosslinking modifying component comprises an acid, and the crosslinking modifying component decrosslinks at least some of the decrosslinkable polymers in the planarization layer.

21. The method of any one of claims 14 to 17 and 20, wherein the polymer capable of generating the crosslinking modified component in the crosslinking modifier layer comprises an acid-producing polymer.

22. The method of claim 21, wherein the acid-generating polymer comprises at least one monomer having an acid-generating group bonded thereto, wherein the acid-generating group is selected from photoacid-generating groups or thermal acid-generating groups.

23. The method of any one of claims 14 to 22, wherein the polymer capable of generating the crosslinking modified component comprises at least one solubility-enhancing monomer and at least one surface adhesion monomer.

24. The method of any one of claims 14 to 23, wherein the forming comprises: The crosslinking modifier composition is heated to form the crosslinking modifier layer, wherein the heating is performed at a temperature of about 150°C to about 215°C for a period of about 45 to about 75 seconds.

25. The method of any one of claims 14 to 24, wherein at least some of the crosslinking modified components diffuse into the planarization layer during and / or after the heating.

26. The method of claim 25, wherein the planarization layer comprises a crosslinkable polymer and a crosslinking agent, wherein the crosslinking modifier diffused into the planarization layer reacts with at least a portion of the crosslinking agent to reduce the degree of crosslinking of the crosslinkable polymer, which would otherwise have occurred during the heating if the crosslinking modifier had not been generated in the crosslinking modifier layer.

27. The method of claim 25, wherein the crosslinking modification component diffused into the planarization layer decrosslinks at least some of the decrosslinkable polymers in the planarization layer.

28. The method of any one of claims 14 to 27, wherein the planarization layer comprises a crosslinkable polymer and a crosslinking agent, wherein during the contact, at least a portion of the crosslinking agent diffuses into the crosslinking modifier layer and reacts with at least a portion of the crosslinking modifier component, and wherein the crosslinking modifier component in contact with the planarization layer reduces the degree of crosslinking, which would have been experienced by the crosslinkable polymer during the heating if the crosslinking modifier component had not been generated in the crosslinking modifier layer.

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