Soluble Polyimides and Diimides for Spin-on Carbon Applications

Abstract

To provide a high-temperature-stable spin-on-carbon ("SOC") material that fills topography features on a substrate while planarizing the surface in a one-step, thin layer coating process.SOLUTION: A material comprises low molecular weight polyimides or diimides that are pre-imidized in a solution rather than on the wafer.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001] Related Applications This application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 063,623, filed August 10, 2020, entitled SOLUBLE POLYIMIDES AND DIIMIDES FOR SPIN-ON CARBON APPLICATIONS, which is incorporated herein by reference in its entirety. [Technical Field]

[0002] The present invention relates generally to methods for manufacturing microelectronic structures.

[0003] 2. Description of Related Art As feature sizes become smaller and smaller in accordance with Moore's Law, photolithography for semiconductor devices is moving toward multilayer patterning. This method involves patterning multiple layers on top of each other, such as a photoresist layer on top of a hard mask layer on top of a spin-on carbon ("SOC") layer, to increase the etch resistance of smaller features. As each layer is deposited and patterned, depositing a uniform planarizing layer of material on top of it becomes important for accurate pattern transfer and critical dimension ("CD") control.

[0004] When depositing a hard mask layer by chemical vapor deposition (CVD), a SOC layer with high-temperature stability is required. Polyimides are known to be thermally stable polymers. They are typically coated onto substrates as polyamic acid precursors. During baking, typically at 200–300°C, the polyamic acid precursors are converted to polyimides, during which the coating thickness typically decreases due to the loss of water and other small molecules. Simultaneously, the polymer is crosslinked through intermolecular imidization and other side reactions. Both coating shrinkage and crosslinking can be detrimental to planarization because shrinkage causes material in trench / via regions with more SOC material to "sink" more easily than material in open areas or on top of lines with less SOC material. This increases the bias between these two regions, thus negatively impacting planarization. Unfortunately, polyamic acids are prematurely crosslinked through intermolecular imidization and other side reactions, rapidly transforming the material from a fluid state to a gel or solid state, limiting thermal reflow.

[0005] Furthermore, SOC is often coated onto substrates made of or coated with SiO2, TiN, and other metals. While dry etching is frequently the preferred method for transferring patterns to substrates, the plasma used in dry etching processes can damage thin oxide and nitride layers. Therefore, wet etching is often used for pattern transfer to substrates when thin oxide or nitride layers are present. Wet etching of titanium nitride (TiN) is performed at mild temperatures (50–70°C) in an SC1 cleaning solution, an aqueous solution of ammonium hydroxide and hydrogen peroxide. One problem with such wet etching is the undesired etching of TiN in protected areas due to undercutting of the SOC layer caused by its weak adhesion to TiN. This undesired etching becomes increasingly problematic as critical dimensions continue to decrease.

[0006] Prior art SOCs formed from polyamic acid are also insoluble in PGMEA, a common solvent used in photoresists, hard masks, and other SOC solutions. Because of their insolubility, prior art SOCs can precipitate in coating equipment, leading to blockages in spin coater drain lines and / or deposits in waste tanks. Summary of the Invention

[0007] In one embodiment, the present disclosure generally relates to a method for forming a microelectronic structure. The method includes optionally forming one or more intermediate layers on a substrate surface. If one or more intermediate layers are present, the uppermost intermediate layer is on the substrate surface. A composition is applied to the uppermost intermediate layer, if present, or to the substrate surface if no intermediate layer is present. The composition includes one or both of a diimide or polyimide dissolved or dispersed in a solvent system. The composition is heated to form a carbon-rich layer, which, when subjected to a CVD survivability test, has a surface area of ​​less than 1000 cm of layer surface area. 2 The CVD survivability test used to determine whether this property is present involves forming a SiOx or SiNx layer on a carbon-rich layer by plasma-enhanced chemical vapor deposition (PECVD) at about 400° C. under vacuum and observing the SiOx or SiNx layer for defects.

[0008] In another embodiment, a method for forming a microelectronic structure is disclosed in which one or more intermediate layers are optionally formed on a substrate surface, and if one or more intermediate layers are present, a topmost intermediate layer is present on the substrate surface. A composition is applied to the topmost intermediate layer, if present, or to the substrate surface if no intermediate layer is present. The composition includes one or both of a diimide and a polyimide dissolved or dispersed in a solvent system. The composition is heated to form a carbon-rich layer having SC1 resistance.

[0009] In a further embodiment, a method for forming a microelectronic structure is provided, the method including optionally forming one or more intermediate layers on a substrate surface. If one or more intermediate layers are present, the uppermost intermediate layer is present on the substrate surface. The composition is applied to the uppermost intermediate layer, if present, or to the substrate surface if no intermediate layer is present. The composition includes one or both of a diimide or polyimide and a component dissolved or dispersed in a solvent system. The component is selected from a polyphenol containing at least four phenolic rings, a polyhydroxy compound, a phosphate compound, and combinations of the foregoing. The composition is heated to form a carbon-rich layer.

[0010] In yet a further embodiment, the present invention provides a method for forming a microelectronic structure, the method comprising imidizing one or both of a diamic acid or a polyamic acid in a solvent system containing propylene glycol monomethyl ether to form a composition comprising one or both of a diimide or a polyimide. If one or more intermediate layers are present, one or more intermediate layers may be formed on the substrate surface, with the uppermost intermediate layer being present on the substrate surface. The composition is applied to the uppermost intermediate layer, if present, or to the substrate surface if no intermediate layer is present, without removing the propylene glycol monomethyl ether. The composition is heated to form a carbon-rich layer.

[0011] The present invention also provides a method for forming a microelectronic structure, the method including optionally forming one or more intermediate layers on a substrate surface, and if one or more intermediate layers are present, a topmost intermediate layer is present on the substrate surface. A composition is applied to the topmost intermediate layer, if present, or to the substrate surface if no intermediate layer is present. The composition includes a polyimide dissolved or dispersed in a solvent system and having a weight average molecular weight of about 2,000 Daltons to about 7,000 Daltons. The composition is heated to form a carbon-rich layer.

[0012] In another embodiment, a composition is provided, the composition comprising: Diimide and Polyphenols containing at least four phenolic rings, polyhydroxy compounds, phosphorus compounds, and A combination of the above and a component selected from a solvent system; and It has.

[0013] In another embodiment, a microelectronic structure is provided that includes a microelectronic substrate having a surface. If one or more intermediate layers are present, one or more intermediate layers may be present on the substrate surface, with a top intermediate layer being present on the substrate surface. A layer of the composition is present on the top intermediate layer, if present, or on the substrate surface if no intermediate layer is present. The composition comprises: one or both of a diimide and a polyimide; Polyphenols containing at least four phenolic rings, polyhydroxy compounds, phosphorus compounds, and A combination of the above and a component selected from Solvent system and Includes.

[0014] In yet a further embodiment, the present invention provides a microelectronic structure comprising a microelectronic substrate having a surface. If one or more intermediate layers are present, one or more intermediate layers may be present on the substrate surface, with a topmost intermediate layer being present on the substrate surface. A carbon-rich layer is present on the topmost intermediate layer, if present, or on the substrate surface if no intermediate layer is present. The carbon-rich layer may be one or both of a crosslinked diimide or a crosslinked polyimide; Polyphenols containing at least four phenolic rings, polyhydroxy compounds, phosphorus compounds, and A combination of the above and an ingredient selected from Includes. [Brief explanation of the drawings]

[0015] [Figure 1] Optical microscope photographs (left: 500x, right: 2,000x) showing examples of CVD survival test results. [Figure 2] FIG. 1 illustrates a test flow for an exemplary SC1 resistance test procedure. [Figure 3] 1 is a scanning electron microscope ("SEM") image (200kx) of a chip coated as described in Example 3 using the formulation of Example 2. [Figure 4] 1 is an SEM image (200kx) of a chip coated as described in Example 3 using the formulation of Example 2. [Figure 5] 1 is an SEM image (200kx) of a chip coated as described in Example 3 using the formulation of Example 2. [Figure 6] 1 is an SEM image of a chip coated as described in Example 5 using the formulation of Example 4. [Figure 7] 1 is an SEM image of a chip coated as described in Example 5 using the formulation of Example 4. [Figure 8] 1 is an SEM image of a chip coated as described in Example 5 using the formulation of Example 4. [Figure 9] 1 is an SEM image of a chip coated as described in Example 7 using the formulation of Example 6. [Figure 10] 1 is an SEM image of a chip coated as described in Example 7 using the formulation of Example 6. [Figure 11] 1 is an SEM image of a chip coated as described in Example 7 using the formulation of Example 6. [Figure 12] 1 is an SEM image (100kx) of a chip coated as described in Example 9 using the formulation of Example 8. [Figure 13]1 is an SEM image (200kx) of a chip coated as described in Example 9 using the formulation of Example 8. [Figure 14] 1 is an SEM image (200kx) of a chip coated as described in Example 9 using the formulation of Example 8. [Figure 15] 1 is an SEM image (200kx) of a chip coated as described in Example 23 using the formulation of Example 20. [Figure 16] 1 is an SEM image (200kx) of a chip coated as described in Example 23 using the formulation of Example 21. [Figure 17] 1 is an SEM image (200kx) of a chip coated as described in Example 23 using the formulation of Example 22. [Figure 18] 1 is an SEM image (200kx) of a chip coated as described in Example 23 using the formulation of Example 12. [Figure 19] 10 is an SEM image (200kx) of a chip coated as described in Example 28 using a control formulation. [Figure 20] 1 is an SEM image (200kx) of a chip coated as described in Example 28 using the formulation of Example 24. [Figure 21] 1 is an SEM image (200kx) of a chip coated as described in Example 28 using the formulation of Example 25. [Figure 22] 1 is an SEM image (200kx) of a chip coated as described in Example 28 using the formulation of Example 26. [Figure 23] 1 is an SEM image (200kx) of a chip coated as described in Example 28 using the formulation of Example 27. DETAILED DESCRIPTION OF THE INVENTION

[0016] FIELD OF THE DISCLOSURE The present disclosure relates generally to high temperature stable spin-on carbon compositions that are particularly suitable for multilayer photolithography applications, and methods of using those compositions and the resulting structures.

[0017] composition The compositions generally comprise a diimide and / or polyimide, along with one or more optional ingredients, dispersed or dissolved in a solvent system, depending on the embodiment.

[0018] 1. Polyimide In one embodiment, commercially available polyimides can be utilized. In another embodiment, the polyimides can be synthesized by imidizing polyamic acids in solution. The polyamic acids can be commercially available polyamic acids or can be synthesized, such as by reacting one or more dianhydrides with one or more diamines in a suitable reaction solvent system, which can include only one solvent or multiple solvents. In embodiments where polyamic acids are synthesized, suitable dianhydrides include aromatic moieties, and preferred aromatic dianhydrides have a flexible structure. As used herein, "flexible structure" describes a structure with aliphatic bonds that allow the bonds in the structure to rotate and bend. Examples of such dianhydrides include those selected from benzophenone-3,3',4,4'-tetracarboxylic dianhydride ("BTDA"), 4,4'-biphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride ("FDAH"), and combinations thereof.

[0019] Diamines suitable for polyamic acid synthesis include aromatic moieties, and preferred aromatic diamines have flexible structures. Examples of such diamines include those selected from 4,4'-oxydianiline ("ODA"), bis(4-aminophenyl)sulfone, 9,9-bis(4-aminophenyl)fluorene ("FDA"), and combinations thereof.

[0020] The polymerization can be carried out in any suitable reaction solvent system, examples of which are selected from dimethylformamide ("DMF"), dimethylacetamide ("DMAC"), N-methyl-2-pyrrolidone ("NMP"), γ-butyrolactone ("GBL"), propylene glycol monomethyl ether acetate ("PGMEA"), propylene glycol monomethyl ether ("PGME"), propylene glycol ethyl ether ("PGEE"), cyclopentanone, and combinations thereof. In one embodiment, a fab-friendly solvent such as PGMEA, PGME, and / or PGEE is used. In another embodiment, the reaction or polymerization solvent system consists essentially of, or even consists of, PGMEA, PGME, and / or PGEE. In another embodiment, the solvent system is essentially free of DMF, DMAC, NMP, and / or GBL. In other words, the solvent system contains less than about 5%, preferably less than about 1%, more preferably about 0% of one or more of DMF, DMAC, NMP and / or GBL, even more preferably a combination of DMF, DMAC, NMP and / or GBL.

[0021] In embodiments where it is desired to obtain a polyamic acid having amino end groups (or at least predominantly amino end groups), the ratio of dianhydride to diamine utilized is preferably from about 1:3 to about 4:5, more preferably from about 1:3 to about 2:3. In embodiments where it is desired to obtain a polyamic acid having anhydride end groups (or at least predominantly anhydride end groups), the ratio of dianhydride to diamine utilized is preferably from about 4:3 to about 14:3, more preferably from about 5:3 to about 10:3. In either embodiment, the polyamic acid preferably has a weight average molecular weight, as determined by GPC, of ​​from about 500 daltons to about 9,000 daltons, preferably from about 2,000 daltons to about 7,000 daltons.

[0022] The dianhydride and diamine monomers are preferably dissolved or dispersed in the reaction solvent in an amount of about 5% to about 20% by weight, more preferably about 7% to about 15% by weight, and most preferably about 10% by weight, based on the total weight of the reaction system. The polycondensation reaction is carried out under nitrogen with stirring at a temperature of about 10°C to about 40°C, preferably about 20°C to about 30°C, for about 12 to about 36 hours, preferably about 16 to about 24 hours.

[0023] The polyamic acid is then preferably end-capped, which can extend the shelf life of the final polyimide, improve spin-bowl compatibility, and increase thermal stability by introducing cross-linkable groups. In embodiments in which the polyamic acid is terminated with amino groups, the end-capper is preferably an anhydride such as one selected from the group consisting of acetic anhydride, phthalic anhydride ("PTA"), succinic anhydride, trimellitic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, 4-ethynylphthalic anhydride ("EPA"), 4-methylethynylphthalic anhydride ("MEPA"), 4-phenylethynylphthalic anhydride ("PEPA"), and combinations thereof.

[0024] In embodiments in which the polyamic acid is terminated with an anhydride group, the end capper is preferably a compound containing an amino group, such as aniline. Particularly preferred are compounds containing an aniline moiety, including those selected from 2,5-dimethoxyaniline, 3,5-dimethoxyaniline, 3,4,5-trimethoxyaniline, 5-amino-1-naphthol, 4'-aminoacetophenone, 1-aminoanthraquinone, 3-ethynylaniline, 4-ethynylaniline, 2-ethynylaniline, and combinations thereof.

[0025] The molar ratio of endcapper to the predominant end group (i.e., anhydride endcapper to terminal amino group, or amino group endcapper to terminal anhydride group) depends on the initial molar ratio of dianhydride to diamine and is selected so that the endcapper reacts completely (or at least substantially completely) with the end groups. For anhydride endcappers, the molar ratio can be calculated as follows: E / B=2(1-A / B) where A is the moles of dianhydride, B is the moles of diamine, and E is the moles of anhydride endcapper. For example, if the initial molar ratio of dianhydride (A) to diamine (B) is about 2:5, the molar ratio of anhydride endcapper (E) to diamine (B) is selected to be about 6:5, or if the initial molar ratio of dianhydride (A) to diamine (B) is about 3:5, the molar ratio of anhydride endcapper (E) to diamine (B) is selected to be about 4:5.

[0026] Similarly, for amino endcappers, the molar ratio can be calculated as follows: F / A=2(1-B / A) where A is the moles of dianhydride, B is the moles of diamine, and F is the moles of amino endcapper. (The factor "2" is necessary because the monomers are difunctional anhydrides and difunctional amines, while the endcappers are monofunctional anhydrides or monofunctional amines.)

[0027] Regardless of the endcapper selected, the endcapping reaction is carried out under nitrogen with stirring at a temperature of about 10°C to about 40°C, preferably about 20°C to about 30°C, for about 12 hours to about 36 hours, more preferably about 16 hours to 24 hours.

[0028] The polymer or end-capped polymer (depending on whether end-capping was utilized) is then imidized by using a dehydration reaction to convert the polyamic acid to a polyimide. Removal of water by azeotropic distillation is desirable for complete imidization because the dehydration / hydrolysis reaction is reversible. Water removal drives the equilibrium forward to complete imidization. A solvent capable of azeotropically distilling with water, such as toluene or xylene, is then added to the reaction mixture in an amount of about 10% to about 40% by weight, preferably about 20% to about 30% by weight, based on the total weight of the entire reaction mixture. The mixture is heated in an inert atmosphere, such as under nitrogen, to a temperature of about 150°C to about 200°C, preferably about 170°C to about 190°C, and more preferably about 180°C. The distillation solvent (e.g., toluene, xylene) is distilled off along with the water and condensed and collected in a Dean-Stark collector or similar. The water then phase separates from the distillation solvent and sinks to the bottom of the collector while the distillation solvent backflows into the reaction vessel. The imidization is allowed to proceed for about 4 hours to about 24 hours, preferably about 8 hours to about 16 hours, or until water stops collecting.

[0029] The crude polyimide solution is then cooled to room temperature. In one embodiment, the polyimide is precipitated from the reaction solution, preferably in methanol or a methanol / acetone mixture in a weight ratio of about 1:5. The precipitated polyimide is filtered and washed, preferably with methanol, acetone, or a combination thereof. The resulting polyimide can be dried in air or under vacuum, preferably at a temperature of about 60°C, for about 10 hours to about 24 hours.

[0030] In another embodiment, the polyimide does not precipitate from the reaction solution, i.e., advantageously, when a fab-friendly solvent such as those discussed above is used as the reaction solvent system, the crude polyimide solution can be used as obtained and no additional precipitation is required.

[0031] In one embodiment, the resulting polyimide has a weight average molecular weight of about 500 daltons to about 9,000 daltons, preferably about 2,000 daltons to about 7,000 daltons, as determined by GPC. In another embodiment, the resulting polyimide has a weight average molecular weight of about 450 daltons to about 8,100 daltons, preferably about 1,800 daltons to about 6,300 daltons, as determined by GPC.

[0032] 2. Diimide In one embodiment, commercially available diimides can be utilized. In another embodiment, the diimides can be synthesized by imidizing diamic acids in solution. The diamic acids can be commercially available or can be synthesized in a suitable reaction solvent system, which can include only one solvent or multiple solvents, such as by reacting one or more dianhydrides with one or more monoamines, or by reacting one or more monoanhydrides with one or more diamines.

[0033] In one embodiment in which a diamic acid is synthesized, one or more dianhydrides and one or more monoamines (preferably crosslinkable) are reacted in a solvent system. Suitable dianhydrides include those selected from benzophenone-3,3',4,4'-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, and combinations thereof. Suitable monoamino compounds are preferably crosslinkable and include those selected from 2-vinylaniline, 4-vinylaniline, 2-allylaniline, 4-allylaniline, 3-ethynylaniline, 4-ethynylaniline, 2-ethynylaniline, and combinations thereof. Suitable reaction solvents include those previously described in the polyimide embodiment, with fabrication-friendly solvents such as PGMEA, PGME, and / or PGEE being preferred. The molar ratio of the crosslinkable monoamino compound to the dianhydride is preferably about 2:1 to about 2.2:1, more preferably about 2:1 to about 2.1:1.

[0034] In another embodiment in which a diamic acid is synthesized, the diamic acid is formed by reacting one or more diamines with one or more monoanhydrides in a solvent system. Suitable diamines include those selected from 4,4'-oxydianiline, bis(4-aminophenyl)sulfone, 9,9-bis(4-aminophenyl)fluorene, and combinations thereof. Suitable monoanhydride compounds are preferably crosslinkable and include those selected from maleic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, 4-ethynylphthalic anhydride ("EPA"), 4-methylethynylphthalic anhydride ("MEPA"), 4-phenylethynylphthalic anhydride ("PEPA"), and combinations thereof. Again, suitable reaction solvents include those previously described for the polyimide embodiment, with fab-friendly solvents such as PGMEA or PGME being preferred. The molar ratio of the monoanhydride compound to the diamine is preferably from about 2:1 to about 2.2:1, more preferably from about 2:1 to about 2.1:1.

[0035] In one embodiment, the reaction solvent system consists essentially of, or even consists of, PGMEA, PGME, and / or PGEE. In another embodiment, the solvent system is essentially free of DMF, DMAC, NMP, and / or GBL. In other words, the solvent system contains less than about 5% by weight, preferably less than about 1% by weight, and more preferably about 0% by weight of one or more of DMF, DMAC, NMP, or GBL. Additionally or alternatively, the total weight of DMF, DMAC, NMP, and GBL in the solvent system is less than about 5% by weight, preferably less than about 1% by weight, and more preferably about 0% by weight.

[0036] Nevertheless, the reaction is carried out similarly to that described above for the polyimide embodiment, with some differences as explained below. The reaction is also carried out under nitrogen with stirring, preferably at a temperature of about 10°C to about 50°C, more preferably about 20°C to about 40°C, for about 12 hours to about 36 hours, more preferably about 16 to 24 hours.

[0037] The diamic acid is then imidized and converted to a diimide using a dehydration reaction. Removal of water by azeotropic distillation is preferred for complete imidization because the dehydration / hydrolysis reaction is reversible. Water removal drives the equilibrium forward to complete imidization. In one embodiment, a solvent capable of azeotropic distillation with water, such as toluene or xylene, is added to the reaction mixture in an amount of about 10% to about 40% by weight, preferably about 20% to about 30% by weight, as a percentage of the total weight of the reaction mixture. The mixture is heated in an inert atmosphere, such as under nitrogen, at a temperature of about 100°C to about 200°C, preferably about 130°C to about 180°C. The distillation solvent (e.g., toluene, xylene) is distilled off along with the water and condensed and collected in a Dean-Stark collector or similar. The water then phase separates from the distillation solvent and sinks to the bottom of the collector, while the distillation solvent flows back into the reaction vessel. In another embodiment, the rapid reaction rate of the imidization reaction is such that a distillation solvent is not required. Imidization is allowed to proceed for about 4 hours to about 24 hours, preferably about 8 hours to about 16 hours, or until water stops collecting.

[0038] The crude diimide solution is then cooled to room temperature and precipitated from the reaction solution, preferably in deionized water or hexane at a weight ratio of about 1:5. The precipitated diimide is filtered and washed, preferably with water, hexane, or a combination thereof. The resulting diimide can be dried in air or under vacuum, preferably at a temperature of about 60°C, for about 10 hours to about 24 hours.

[0039] In another embodiment, the diimide does not precipitate from the reaction solution, i.e., advantageously, when a fab-friendly solvent is used as the reaction solvent system, the crude polyimide solution can be used as obtained and no additional precipitation is required.

[0040] Regardless of the embodiment, the diimide formed preferably has a weight average molecular weight of less than about 1,000 daltons, more preferably from about 500 daltons to about 1,000 daltons, and even more preferably from about 600 daltons to about 800 daltons.

[0041] 3. Composition In both polyimide and diimide embodiments, the compositions of the present invention comprise the above-described polyimides and / or diimides dispersed or dissolved in a solvent system. In either embodiment, each composition may individually contain optional components such as those selected from crosslinkers, surfactants, polymers, catalysts, additives, and mixtures thereof.

[0042] In each of the foregoing compositions, the polyimide and / or diimide is preferably present in the particular composition at about 2% to about 50% by weight solids, more preferably about 3% to about 30% by weight solids, and even more preferably about 5% to about 10% by weight solids, based on 100% by weight of the total weight of the composition.

[0043] In one embodiment, one or more additives may be included in the composition.One suitable additive is selected from polyphenols, particularly those containing 4, 5, 6 or more phenol rings.In one embodiment, the polyphenol contains at least two unsubstituted phenol rings.

[0044] Some preferred polyphenols are those disclosed in U.S. Patent Application Publication No. 2021 / 0040290, which is incorporated herein by reference, and those supplied by Mitsubishi Gas Chemical Company, Inc. under the trade names NeoFARIT 7177C and 7177D ("NF7177C" and "NF7177D"). Particularly preferred polyphenols include: [ka] where n is 1 to 5. In the above structure, the repeat unit is shown attached to the α carbon. In some embodiments, the repeat unit can be attached to the α' carbon instead of the α carbon. In other embodiments, both the α carbon and the α' carbon can contain repeat units, and each n is independently selected from 1 to 5.

[0045] Other suitable additives include hydroxy compounds, particularly polyhydroxy compounds. In one embodiment, preferred hydroxy compounds have three or more hydroxy groups, more preferably three to six hydroxy groups. In another embodiment, the hydroxy compounds contain aromatic moieties (e.g., benzene rings) substituted with the hydroxy groups. Examples of suitable hydroxy compounds include those selected from gallic acid, methyl gallate, 4-hydroxybenzoic acid, 1,2-dihydroxybenzene, pyrogallol, 2,3,4,3',4',5'-hexahydroxybenzophenone ["6HBP"], 3,3',5,5'-tetrakis(methoxymethyl)-[1,1'-biphenyl]-4,4'-diol [TMOM-BP], poly(4-vinylphenol), and combinations thereof.

[0046] Phosphorus compounds are another type of additive that can be used in some embodiments of the composition of the present invention.Preferred phosphate compounds include phosphine, phosphine oxide, phosphonate and / or phosphate groups.Examples of suitable phosphate compounds include those selected from phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, dimethylphenylphosphonate, phenylphosphate, phenylphosphonic acid, phytic acid, and combinations thereof.

[0047] Each included additive is preferably present individually in a particular composition at a level of from about 0.5% to about 10% by weight solids, more preferably from about 1% to about 3% by weight solids, based on 100% weight total solids. Alternatively or additionally, the total weight of all additives present in combination preferably falls within the aforementioned ranges.

[0048] In some embodiments, surfactants can be included in the composition to improve coating quality. Nonionic surfactants such as R30N (DIC Corporation, Japan) and FS3100 (The Chemours Company FC, LLC, USA) are particularly preferred. The surfactant is preferably present in a particular composition at about 0.05% to about 0.5% by weight of solids, more preferably about 0.1% to about 0.3% by weight of solids, based on 100% weight of total solids.

[0049] The above components (polyimide and / or diimide and optional additives and / or surfactants) are mixed in a solvent system to form a specific composition. Preferred solvent systems include cyclopentanone, cyclohexanone, or a solvent selected from the group consisting of PGMEA, PGME, PGEE, ethyl lactate, GBL, and mixtures thereof. The solvent system is preferably utilized at a level of about 50% to about 98% by weight, more preferably about 60% to about 95% by weight, and even more preferably about 85% to about 95% by weight, based on 100% weight of the total composition. It will be appreciated that if the reaction solvent is also the formulation solvent (e.g., PGME, PGMEA, or PGEE), no further isolation or precipitation is required after synthesis. That is, there is no need to remove the solvent (which avoids, for example, the prior art need to remove NMP), and there is no need to remove the polymer from the solvent. The composition can simply be further diluted with the desired solvent to reach a final solvent level of about 50% to about 98% by weight, preferably about 85% to about 95% by weight, based on the total weight of the composition taken as 100% by weight, with the total solids range being the balance above to bring the composition to 100% by weight. The material is preferably filtered, such as with a 0.1 μm or 0.2 μm PTFE filter, before use.

[0050] In one embodiment, the composition consists essentially of, or alternatively consists of, a polyimide and / or diimide dispersed or dissolved in a solvent system, hi another embodiment, the composition consists essentially of, or alternatively consists of, a polyimide and / or diimide dispersed or dissolved in a solvent system and one, two, three, four, or all five of a crosslinker, a surfactant, a polymer, a catalyst, and / or an additive.

[0051] Method of using the composition More specifically, the present invention provides a method for forming microelectronic structures that are particularly suitable for lithography. In the method of the present invention, a substrate having a surface is provided. Any microelectronic substrate can be utilized. The substrate is preferably a semiconductor substrate, such as silicon, SiGe, SiO2, Si3N4, SiON, aluminum, tungsten, tungsten silicide, gallium arsenide, germanium, tantalum, tantalum nitride, Ti3N4, hafnium, HfO2, ruthenium, indium phosphide, a combination of tetramethylsilane and tetramethylcyclotetrasiloxane (such as those sold under the name CORAL), SiCOH (such as those sold under the name Black Diamond by SVM, Santa Clara, California), glass, or a mixture thereof. An optional intermediate layer can be formed on the substrate before processing, with one particularly preferred intermediate layer being TiN. The substrate can have a flat surface or can include topographical features (via holes, trenches, contact holes, raised features, lines, etc.). As used herein, "topography" refers to the height or depth of structures in or on a substrate surface.

[0052] A layer of the SOC composition of the present invention is formed on a substrate or an optional intermediate layer. The SOC layer can be formed by any known application method. One preferred method is spin coating at a speed of about 1,000 rpm to about 2,000 rpm, preferably about 1,200 rpm to about 1,500 rpm, for a time of about 30 seconds to about 90 seconds, preferably about 45 seconds to 60 seconds. Preferably, the composition of the present invention has good spin-bowl compatibility, i.e., the composition of the present invention does not react with or form precipitates in common photoresist solvents such as PGME, PGMEA, ethyl lactate, cyclohexanone, or combinations thereof.

[0053] After application of the carbon-rich composition, it is preferably heated to a temperature of about 100°C to about 250°C, more preferably about 170°C to about 230°C, for about 30 to about 90 seconds, preferably about 45 to about 60 seconds, to evaporate the solvent. SOC compositions advantageously have fast thermal reflow; that is, at temperatures above about 200°C, the viscosity of the composition is less than about 10 cP, as measured by a rheometer.

[0054] The average thickness of the baked SOC or carbon-rich layer is preferably about 50 nm to about 2.5 μm, more preferably about 80 nm to about 150 nm, and even more preferably about 100 nm to about 120 nm. The average thickness is determined by averaging thickness measurements at five different locations on the SOC layer, which thickness measurements are obtained using ellipsometry.

[0055] After baking, the formed SOC layer preferably contains greater than about 75% carbon by weight, more preferably greater than about 80% carbon by weight, and even more preferably about 85% to about 90% carbon by weight, based on the baked layer as 100% by weight. The SOC layer preferably has high-temperature stability with little or no thermal decomposition below about 500°C. For example, the SOC layer described herein exhibits less than about 10% weight loss when heated to about 400°C for about 10 minutes, and even more preferably less than about 10% weight loss when heated to about 500°C for about 10 minutes, as measured using thermogravimetric analysis.

[0056] Additionally, the SOC layer contains a majority of any additives that were included in the SOC composition from which the layer was formed, i.e., the baked SOC layer retains at least about 50% by weight of the amount of starting additive, preferably at least about 80% by weight, more preferably at least about 90% by weight, and even more preferably at least about 95% by weight.

[0057] In one embodiment, the final SOC layer comprises from about 0.25% to about 9.5% by weight, preferably from about 0.4% to about 8% by weight, more preferably from about 0.6% to about 5% by weight, and even more preferably from about 0.8% to about 2.5% by weight of one or more of the aforementioned additives, based on the total weight of the layer as 100%. Alternatively or additionally, the total weight of the combination of all additives present in the final layer preferably falls within the aforementioned ranges.

[0058] Preferably, the SOC layer exhibits little or no shrinkage. That is, the average thickness decreases by less than about 5% after heating to about 400°C for about 10 minutes, and more preferably, the average thickness decreases by less than about 5% after heating to about 500°C for about 10 minutes. In some cases, the shrinkage of the SOC layer may be negative, meaning that the layer thickness increases after the described bake conditions, indicating swelling of the SOC layer. (In these cases, it is theorized that the SOC layer becomes less dense after the high-temperature bake, resulting in less weight loss but slight swelling of the film.) In one embodiment, the SOC layer has good SC1 resistance, in that it is unaffected by exposure to SC1 cleaning solution at about 60°C for more than about 30 minutes.

[0059] The hard mask layer can be applied adjacent to the SOC layer or to any intermediate layer that may be present on the SOC layer. The hard mask layer can be formed by any known application method, such as chemical vapor deposition ("CVD") or plasma-enhanced chemical vapor deposition ("PECVD"). Another preferred method involves spin-coating at a speed of about 1,000 rpm to about 5,000 rpm, preferably about 1,250 rpm to about 1,750 rpm, for a time of about 30 seconds to about 120 seconds, preferably about 45 seconds to about 75 seconds. A suitable hard mask layer should have a high etch bias relative to the underlying layer. A preferred hard mask layer has a high silicon content material, preferably at least about 30% by weight, more preferably about 35% to about 40% by weight silicon, based on the total weight of the hard mask layer. Suitable hard mask layers are commercially available and can be formed from compositions including polymers or oligomers (e.g., silanes, siloxanes, silsesquioxanes, silicon oxynitride, silicon nitride, polysilicon, amorphous silicon, and combinations thereof) dissolved or dispersed in a solvent system. Some preferred monomers or polymers for use in the hard mask layer are selected from the group including phenethyltrimethoxysilane ("PETMS"), 2-(carbomethoxy)ethyltrimethoxysilane ("CMETMS"), tetraethoxysilane ("TEOS"), methyltrimethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane ("MTMS"), ethyltrimethoxysilane ("ETMS"), (3-glycidioxypropyl)triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane ("ECHTMS"), and mixtures thereof. Optional ingredients (e.g., surfactants, acid catalysts, base catalysts, and / or crosslinkers) are dissolved in the solvent system along with the polymer, monomer, and / or oligomer. Preferred hard mask compositions preferably have from about 0.1% to about 70%, more preferably from about 0.5% to about 10%, and even more preferably from about 0.5% to about 1% solids by weight, based on the total weight of the composition, taken as 100% by weight.

[0060] After application of the hard mask composition, the hard mask is heated to a temperature of preferably about 100°C to about 300°C, more preferably about 150°C to about 250°C, for about 30 seconds to about 120 seconds, preferably about 45 seconds to about 60 seconds, to evaporate the solvent. The average thickness of the baked hard mask layer (measured at five locations by ellipsometry and averaged) is preferably about 5 nm to about 50,000 nm, more preferably about 5 nm to about 1,000 nm, and even more preferably about 10 nm to about 30 nm.

[0061] Advantageously, the SOC layer of the present invention can withstand harsh CVD processes, such as those used to apply the hard mask layer described above on top of the SOC layer. To determine whether the SOC layer can withstand typical CVD semiconductor manufacturing processes, a "CVD survivability test" is performed by coating a topographical chip (preferably, a chip with various topographical features, including, but not limited to, 50 nm lines / spaces, relaxed pitch features, large features, 50 μm lines with large spaces of about 50 μm, and / or contact holes / vias with 100 nm or 200 nm deep features) with the SOC composition to be tested, followed by baking on a hot plate at about 170°C for about 1 minute, and then in a furnace in a N2 atmosphere at about 450°C for about 4 minutes to form a hardened SOC layer with an average thickness of about 180 nm. The coated chip is then deposited with a SiOx or SiNx test film using PECVD at about 400°C in a high vacuum. After PECVD deposition, the chip is examined under an optical microscope. A fail or pass decision is based on the number of defects (bubbles, peeling, wrinkles, and / or cracks) the CVD-deposited film experiences. Films that pass the CVD survivability test have a CVD film defect count of approximately 0.1 defects / cm when viewed under an optical microscope. 2 (i.e., less than about 15 defects per 8-inch wafer), and preferably, the CVD film has a defect count of about 0.05 / cm 2 (i.e., less than about 7.5 defects per 8-inch wafer), and more preferably, the CVD film has a defect count of about 0 / cm 2Examples of failed and passed CVD survivability tests are shown in Figure 1. An SOC or carbon-rich composition or layer that performs within these parameters with at least one of an SiOx or SiNx test film is considered to have CVD survivability characteristics. In particularly preferred embodiments, the SOC layer has CVD survivability when subjected to this test with an SiOx test film and also when subjected to this test with an SiNx test film.

[0062] A photoresist (i.e., an imaging layer) can then be applied to the SOC or any intermediate layer to form a photoresist layer. The photoresist layer can be formed by any conventional method; one preferred method is spin-coating the photoresist composition at a speed of about 350 rpm to about 4,000 rpm (preferably about 1,000 rpm to about 2,500 rpm) for about 10 seconds to about 60 seconds (preferably about 10 seconds to about 30 seconds). The photoresist layer is then optionally post-apply baked ("PAB") at a temperature of at least about 70°C, preferably about 80°C to about 150°C, and more preferably about 100°C to about 150°C, for about 30 seconds to about 120 seconds. The average thickness of the photoresist layer after baking (determined as described above) is typically about 5 nm to about 120 nm, preferably about 10 nm to about 50 nm, and more preferably about 20 nm to about 40 nm.

[0063] The photoresist layer is then irradiated with approximately 10 mJ / cm 2 ~about 200mJ / cm 2 , preferably about 15 mJ / cm 2 ~about 100mJ / cm 2 , more preferably about 20 mJ / cm 2 ~about 50mJ / cm 2The photoresist layer is patterned by exposure to a dose of radiation. More specifically, the photoresist layer is exposed using a mask positioned above the surface of the photoresist layer. The mask has areas designed to allow radiation to reflect off or pass through the mask and contact the surface of the photoresist layer. The remaining portions of the mask are designed to absorb light to prevent radiation from contacting the surface of the photoresist layer in certain areas. Those skilled in the art will readily understand that the arrangement of the reflective and absorbing portions is designed based on the desired pattern to be formed in the photoresist layer, and ultimately in the substrate or any intermediate layers.

[0064] After exposure, the photoresist layer undergoes a post-exposure bake ("PEB") at a temperature of less than about 180°C, preferably from about 60°C to about 140°C, and more preferably from about 80°C to about 130°C, for a time of from about 30 seconds to about 120 seconds (preferably from about 30 seconds to about 90 seconds).

[0065] The photoresist layer is then contacted with a developer to form a pattern. Depending on whether the photoresist used is a positive- or negative-tone process, the developer either removes the exposed portions of the photoresist layer or removes the unexposed portions of the photoresist layer to form the pattern. The pattern is then transferred through the various layers and finally to the substrate. This pattern transfer can be accomplished via plasma etching (e.g., CF4 etchant, O2 etchant) or wet etching or development processes.

[0066] In one embodiment, once the layer of the present invention is patterned, an SC1 etch can be used to open up a metal layer (e.g., TiN) that is used as another hard mask to further transfer the pattern into the substrate. The SOC layer of the present invention suffers little or no undercutting, meaning it protects the metal layer from dissolution where the SOC layer is present.

[0067] The "SC1 resistance test" is performed by spin-coating a 180 nm thick coating of a carbon-rich composition onto a TiN-liner topography substrate, followed by baking it on a hotplate at about 170 °C for about 1 minute and in a furnace in a N2 atmosphere at about 450 °C for about 4 minutes. The layer is then etched back with an O2 plasma to partially remove the material to the mid-depth of the trench, and the substrate is immersed in an SC1 etchant bath at about 60 °C for about 100 seconds. SEM (200kx) cross-sectional analysis is performed to determine the undercut depth. Figure 2 shows the SC1 test flow and the method for measuring the undercut depth. The wafer in Figure 2 was an SC1 wafer with an ALD layer of TiN with 50 nm line / space and 200 nm deep features. Preferably, the undercut depth is less than about 60 nm, more preferably less than about 30 nm, and even more preferably between about 0.1 nm and about 20 nm. A SOC or carbon-rich composition or layer that operates within these parameters is considered to have the property of being SC1 resistant.

[0068] Further advantages of various embodiments will be apparent to those skilled in the art upon review of the disclosure herein and the examples below. It will be understood that the various embodiments described herein are not necessarily mutually exclusive, unless otherwise indicated herein. For example, features described or illustrated in one embodiment may, but are not necessarily, included in other embodiments. Thus, the present disclosure encompasses various combinations and / or integrations of the specific embodiments described herein.

[0069] As used herein, the word "and / or," when used in a list of two or more items, means that any one of the listed items can be used alone, or any combination of two or more of the listed items can be used. For example, if a composition is described as containing or excluding components A, B, and / or C, the composition can contain or exclude A alone, B alone, C alone, 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.

[0070] This specification also uses numerical ranges to quantify certain parameters for various embodiments. When numerical ranges are provided, it should be understood that such ranges should be interpreted as providing literal support for claim limitations that recite only the lower limit of the range as well as for claim limitations that recite only the upper limit of the range. For example, a disclosed numerical range of about 10 to about 100 literally supports a claim reciting "greater than about 10" (without an upper limit) and a claim reciting "less than about 100" (without a lower limit). [Example]

[0071] The following examples illustrate methods according to the present disclosure, however, it should be understood that these examples are provided by way of illustration and that nothing therein should be construed as a limitation on the overall scope.

[0072] [Example 1] 1. Synthesis of polyamic acid In this example, 12.866 grams of 9,9-bis(4-aminophenyl)fluorene ("FDA", JFE, Japan) was dissolved in 115.741 grams of N-methyl-2-pyrrolidone ("NMP", Sigma Aldrich, St. Louis, MO) in a 500 ml round-bottom flask. 7.144 grams of benzophenone-3,3',4,4'-tetracarboxylic dianhydride ("BTDA", Sigma Aldrich, St. Louis, MO) was dissolved in 64.081 grams of NMP, and the solution was added to an addition funnel, which was connected to the round-bottom flask. The system was purged with nitrogen for 10 minutes. The BTDA solution was then added dropwise to the FDA solution and magnetically stirred under nitrogen for 20 minutes. The reaction was allowed to proceed at room temperature under nitrogen with magnetic stirring for 32 hours.

[0073] 2. End-capping of polyamic acid To the polyamic acid solution obtained in Part 1 above, a solution of 3.443 grams of phthalic anhydride ("PTA", Sigma Aldrich, St. Louis, MO) in 31.033 grams of NMP was added under nitrogen with magnetic stirring. The reaction was allowed to proceed at room temperature under nitrogen with magnetic stirring for 21 hours.

[0074] 3. Solution imidization of polyamic acid To the end-capped polyamic acid solution obtained in Part 2, 50 grams of toluene (Sigma-Aldrich, St. Louis, MO) was added. A Dean-Stark collector was connected to the reaction flask. The flask was immersed in an oil bath heated to 180°C. Water-toluene azeotropic distillation began when imidization began between 150°C and 160°C. The reaction proceeded at these temperatures with magnetic stirring under nitrogen for 8 hours, after which the system was cooled to room temperature.

[0075] [Example 2] 1. Purification of polyimide In this procedure, 20 grams of the polyimide solution obtained in Example 1 was precipitated in 100 grams of acetone (Sigma Aldrich, St. Louis, MO). The precipitated polyimide was filtered, washed with acetone, and then air-dried. GPC with polystyrene standards showed a single peak with Mw=8637, Mn=6229, and PDI=1.39.

[0076] 2. Coating formulation Next, 0.536 grams of the polymer solid from Part 1 was dissolved in 9.536 grams of cyclopentanone (Sigma Aldrich, St. Louis, MO). The solution was filtered through a 0.1 μm PTFE membrane filter (General Electric, UK).

[0077] [Example 3] Flattening Test The solution prepared in Example 2 was spin-coated at 1,500 rpm for 60 seconds onto chips containing lines of different densities (220 nm CD with 1:1, 1:2, or 1:5 line / space ratios and 100 nm-high features). The chips were baked at 170°C for 1 minute on a hotplate and at 450°C for 4 minutes in a furnace. The chips were examined by SEM. The results showed that the lines were well planarized (see Figure 3 (1:1 line / space), Figure 4 (1:2 line / space), and Figure 5 (1:5 line / space)).

[0078] [Example 4] 1. Synthesis of polyamic acid In this example, 6.33 grams of FDA was dissolved in 56.11 grams of NMP in a 500 ml round-bottom flask. 4.996 grams of 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (FDAH, JFE, Japan) was dissolved in 45.367 grams of NMP, and the solution was added to an addition funnel, which was connected to the round-bottom flask. The system was purged with nitrogen for 10 minutes. The FDAH solution was then added dropwise to the FDA solution and magnetically stirred under nitrogen for 17 minutes. The reaction was allowed to proceed at room temperature under nitrogen with magnetic stirring for 19 hours.

[0079] 2. End-capping of polyamic acid To the polyamic acid solution from Part 1, 2.19 grams of acetic anhydride (Sigma Aldrich, St. Louis, MO) was added under nitrogen with magnetic stirring. The reaction was allowed to proceed at room temperature under nitrogen with magnetic stirring for 24 hours.

[0080] 3. Solution imidization of polyamic acid To the end-capped polyamic acid solution, 27.40 grams of toluene was added. A Dean-Stark collector was connected to the reaction flask. The flask was immersed in an oil bath heated to 180°C. Water-toluene azeotropic distillation began when imidization began between 150°C and 160°C. The reaction was allowed to proceed at these temperatures with magnetic stirring under nitrogen for 8 hours. The system was then cooled to room temperature.

[0081] 4. Purification of Polyimide Next, 100 grams of the polyimide solution obtained in Part 3 was precipitated in 500 grams of a 50:50 acetone / methanol mixture (Sigma Aldrich, St. Louis, MO). The precipitated polyimide was filtered, washed with 50:50 acetone / methanol, and then air-dried. GPC showed a single peak with Mw=3772, Mn=3145, and PDI=1.20.

[0082] 5. Coating formulation To prepare the coating formulation, 1.021 grams of the polymer solid obtained in Part 5 was dissolved in 15.585 grams of cyclopentanone. 0.104 grams of 1% R30N surfactant (DIC Corporation, Japan) was added. The solution was filtered through a 0.1 μm PTFE membrane filter.

[0083] [Example 5] Flattening Test The solution prepared in Example 4 was spin-coated at 1,500 rpm for 60 seconds onto a chip containing lines of varying density. The chip was baked on a hotplate at 170°C for 1 minute and in a furnace at 450°C for 4 minutes. The chip was examined under SEM. The results showed good planarization, as seen in Figures 6-8. The chip in Figure 6 had 50 nm lines spaced 250 nm apart on the left, a 1.5 micron gap, and then 50 nm lines spaced 50 nm apart. Figure 7 is a more intense magnification of the 1:1 region, and Figure 8 shows the 1:1 region on the left and a 50 μm oxide pad on the right, with a 500 nm trench between the dense pad and the pad.

[0084] [Example 6] 1. Synthesis of polyamic acid In this example, 9.507 grams of FDA was dissolved in 60.25 grams of NMP in a 500 ml round-bottom flask. 5.002 grams of FDAH was dissolved in 99.50 grams of NMP, and the solution was added to an addition funnel, which was connected to the round-bottom flask. The system was purged with nitrogen for 10 minutes. The FDAH solution was then added dropwise to the FDA solution and magnetically stirred under nitrogen for 20 minutes. The reaction was allowed to proceed at room temperature under nitrogen with magnetic stirring for 24 hours.

[0085] 2. End-capping of polyamic acid To the polyamic acid solution prepared in Part 1 above, 8.136 grams of 4-phenylethynylphthalic anhydride ("PEPA", TCI America, Portland, OR) was added under nitrogen with magnetic stirring. The reaction was allowed to proceed at room temperature under nitrogen with magnetic stirring for 28 hours.

[0086] 3. Solution imidization of polyamic acid To the end-capped polyamic acid solution obtained in Part 1 above, 40.36 grams of toluene was added. A Dean-Stark collector was attached to the reaction flask. The flask was immersed in an oil bath heated to 180°C. Water-toluene azeotropic distillation began when imidization began between 150°C and 160°C. The reaction was allowed to proceed at these temperatures with magnetic stirring under nitrogen for 8 hours, after which the system was cooled to room temperature.

[0087] 4. Purification of Polyimide Next, 100 grams of the polyimide solution obtained in Part 3 above was precipitated in 500 grams of methanol. The precipitated polyimide was filtered, washed with methanol, and then air-dried. GPC analysis showed Mw=2567, Mn=1716, and PDI=1.49.

[0088] 5. Coating formulation A coating formulation was prepared by dissolving 5.014 grams of the polymer solid from Part 4 in 134.445 grams of cyclopentanone. Next, 7.508 grams of 2% NF7177C (to improve adhesion; Mitsubishi Gas Chemical Company, Japan) and 0.501 grams of 1% R30N surfactant were added. The solution was filtered through a 0.1 μm PTFE membrane filter.

[0089] [Example 7] Flattening Test The solution from Example 6 was spin-coated at 1,500 rpm for 60 seconds onto a chip containing lines of varying density. The chip was baked on a hotplate at 170°C for 1 minute and in a furnace at 450°C for 4 minutes. The chip was examined under SEM. The results showed good planarization, as shown in Figures 9-11. The chip in Figure 9 had 50 nm lines spaced 250 nm apart on the left, a 1.5 micron gap, and then 50 nm lines spaced 50 nm apart. Figure 10 is a more intense magnification of the 1:1 region, and Figure 11 shows the 1:1 region on the left and a 50 μm oxide pad on the right, with a 500 nm trench between the dense pad and the pad.

[0090] [Example 8] 1. Synthesis of diamic acid in NMP In this example, 9.169 grams of FDAH was added to a 500 ml round-bottom flask. Next, 4.747 grams of 3-ethynylaniline (3-EA, TCI America, Portland, Oregon) was dissolved in 155.00 grams of NMP, and the solution was added to an addition funnel, which was connected to the round-bottom flask. The system was purged with nitrogen for 10 minutes. The 3-EA solution was then added dropwise to the flask and magnetically stirred under nitrogen for 5 minutes. The reaction was allowed to proceed at room temperature under nitrogen with magnetic stirring for 24 hours.

[0091] 2. Solution imidization of diamic acid Next, 166 grams of toluene was added to the solution obtained in Part 1. A Dean-Stark collector was connected to the reaction flask. An oil bath immersed in the flask was heated to 180°C. The water-toluene azeotropic distillation began when imidization began between 150°C and 160°C. The reaction proceeded at these temperatures with magnetic stirring under nitrogen for 8 hours, after which the system was cooled to room temperature.

[0092] 3. Purification of Diimide The diimide solution was rotary evaporated to remove toluene. It was then precipitated in DI water (weight ratio 1:10). The precipitated diimide was filtered and washed with DI water. It was dried under a stream of nitrogen. GPC analysis using NMP as the mobile phase showed Mw=1168, Mn=973, and PDI=1.20.

[0093] 4. Coating formulation A coating formulation was prepared by dissolving 1.672 grams of the diimide solid from Part 3 above in 22.237 grams of cyclopentanone. Next, 2.516 grams of 2% NF7177C and 1.675 grams of 0.1% R30N surfactant were added. The solution was filtered through a 0.1 μm PTFE membrane filter.

[0094] [Example 9] Flattening Test The solution prepared in Example 8 was spin-coated at 1,500 rpm for 60 seconds onto a chip containing lines of varying density. The chip was baked on a hotplate at 170°C for 1 minute and in a furnace at 450°C for 4 minutes. The chip was examined by SEM. The results showed good planarization, as shown in Figures 12-14. The chip in Figure 12 had 50 nm lines with 50 nm spacing on the left, a 1.5 micron gap, and then 50 nm lines with 250 nm spacing. Figure 13 is a more intense magnification of the 1:1 region, and Figure 14 shows the 50 μm oxide block on the left and the 1:1 region on the right, with a 500 nm trench between them.

[0095] [Example 10] 1. Diimide Synthesis with PGMEA In this example, 27.18 grams of FDAH was added to a 500 ml round-bottom flask. Next, 13.94 grams of 3-EA was dissolved in 163.56 grams of PGMEA (General Chemical Corporation, USA), and the solution was added to an addition funnel, which was then connected to the round-bottom flask. The system was purged with nitrogen for 10 minutes. The 3-EA solution was added dropwise to the flask and magnetically stirred under nitrogen for 4 minutes. The reaction was allowed to proceed at room temperature under nitrogen with magnetic stirring for 4 hours, after which the flask was connected to a condenser and the reaction temperature was increased to 150°C. The imidization reaction was allowed to proceed under nitrogen with magnetic stirring for 8 hours at 150°C.

[0096] 2. Purification of Diimide The diimide solution obtained in Part 1 above was precipitated in hexane (1:5 weight ratio, Sigma Aldrich, St. Louis, MO). The precipitated diimide was filtered, washed with hexane (Tedia High Purity Solvents, Fairfield, OH), and then dried overnight in a vacuum oven at 70 °C.

[0097] [Example 11] 1. Diimide Synthesis with PGME In this example, 26.43 grams of FDAH was added to a 500 ml round-bottom flask. Next, 13.57 grams of 3-EA was dissolved in 60 grams of PGME (General Chemical Corporation, USA), and the solution was added to an addition funnel, which was then connected to the round-bottom flask. The system was purged with nitrogen for 10 minutes, after which the 3-EA solution was added dropwise to the flask and magnetically stirred under nitrogen for 4 minutes. The reaction was allowed to proceed under nitrogen at 50°C for 8 hours with magnetic stirring. The flask was then connected to a condenser, and the reaction temperature was increased to 130°C. The imidization reaction was allowed to proceed under nitrogen at 150°C for 16 hours with magnetic stirring.

[0098] 2. Purification of Diimide The diimide solution obtained in Part 1 above was precipitated in hexane (1:5 weight ratio, Sigma Aldrich, St. Louis, MO). The precipitated diimide was filtered, washed with hexane (Tedia High Purity Solvents, Fairfield, OH), and then dried overnight in a vacuum oven at 70 °C.

[0099] [Example 12] Coating Compounds A coating formulation was prepared by dissolving 3.88 grams of the diimide solid from Example 10 in 81.7 grams of PGMEA and 4.8 grams of PGME. Next, 5.82 grams of 2% NF7177C and 3.8 grams of 0.1% R30N surfactant were added. The solution was filtered through a 0.1 μm PTFE membrane filter.

[0100] [Example 13] Coating Test The coating formulation prepared in Example 12 was spin-coated onto a silicon wafer at 1,500 rpm for 60 seconds. The wafer was baked on a hotplate at 170°C for 1 minute and in a furnace at 450°C for 4 minutes. After baking at 170°C for 1 minute, the coating thickness was 114.6 nm. After baking at 450°C for 4 minutes, the coating thickness was 112.9 nm, with a loss of less than 5% of the total thickness.

[0101] [Example 14] Coating Compounds In this example, 5.03 grams of the diimide solid from Example 10 was dissolved in 85.45 grams of PGMEA and 4.6 grams of PGME. Next, 0.146 grams of gallic acid and 4.8 grams of 0.1% R30N surfactant were added. The solution was filtered through a 0.1 μm PTFE membrane filter.

[0102] [Example 15] Coating Test The coating formulation from Example 14 was spin-coated onto a silicon wafer at 1,500 rpm for 60 seconds. The wafer was baked on a hotplate at 170°C for 1 minute and in a furnace at 450°C for 4 minutes. After baking at 170°C for 1 minute, the coating thickness was 99.8 nm. After baking at 450°C for 4 minutes, the coating thickness was 101.4 nm, indicating no thickness loss but potentially slight swelling of the coating.

[0103] [Example 16] Coating Compounds In this example, 5.00 grams of the diimide solid from Example 10 was dissolved in 85.25 grams of PGMEA and 4.75 grams of PGME. 5.0 grams of 0.1% R30N surfactant was then added. The solution was filtered through a 0.1 μm PTFE membrane filter.

[0104] [Example 17] Coating Test The solution from Example 16 was spin-coated onto a silicon wafer at 1,500 rpm for 60 seconds. The wafer was baked on a hotplate at 170°C for 1 minute and in a furnace at 450°C for 4 minutes. After baking at 170°C for 1 minute, the coating thickness was 119.5 nm. After baking at 450°C for 4 minutes, the coating thickness was 122.7 nm, indicating no thickness loss but potentially slight swelling of the coating.

[0105] [Example 18] 1. Synthesis of diimides using FDA and EPA In a 200 mL round-bottom flask, 3.48 grams of FDA and 3.44 grams of 4-ethynylphthalic anhydride ("EPA", Neximid 200, Nexam Chemical Holding AB, Lomma, Sweden) were added, followed by 27.68 grams of PGMEA. The flask was then connected to a condenser and nitrogen was purged through the system. The flask was then placed in a 150°C oil bath and run for 80 minutes. Upon completion of the reaction, the flask was removed from the oil bath and cooled to room temperature. The resulting solution was precipitated into approximately 0.5 liters of hexane, and the solid was filtered off. The resulting polymer solid was dried under vacuum at 40°C overnight.

[0106] 2. Coating formulation In this example, 0.5988 g of the final dried solid, 14.28 g of cyclopentanone, and 0.12 g of FS3100 (1% solution in cyclopentanone) surfactant (The Chemours Company FC, LLC., USA) were stirred until dissolved. The solution was filtered through a 0.1 μm endpoint filter and bottled for further use.

[0107] [Example 19] Coating Test The coating formulation prepared in Example 18 was spin-coated onto a 100 mm silicon wafer at 1,500 rpm for 60 seconds. The wafer was baked on a hotplate at 170°C for 1 minute and in a furnace at 450°C for 4 minutes. After baking at 170°C for 1 minute, the coating thickness was 157.3 nm. After baking at 450°C for 4 minutes, the coating thickness was 163.0 nm, indicating no thickness loss but potentially slight swelling of the coating.

[0108] [Example 20] Coating Compounds In this example, 4.72 grams of the diimide solid from Example 10 was dissolved in 90.3 grams of PGMEA and 4.8 grams of PGME. Next, 0.14 grams of NF7177C, 0.14 grams of gallic acid, and 4.7 grams of 0.1% R30N surfactant were added. The solution was filtered through a 0.1 μm PTFE membrane filter.

[0109] [Example 21] Coating Compounds In this example, 4.72 grams of the diimide solid from Example 10 was dissolved in 90.3 grams of PGMEA and 4.8 grams of PGME. Next, 0.14 grams of NF7177C, 0.14 grams of 2,3,4,3',4',5'-hexahydroxybenzophenone ("6-HBP"), and 4.7 grams of 0.1% R30N surfactant were added. The solution was filtered through a 0.1 μm PTFE membrane filter.

[0110] [Example 22] Coating Compounds In this example, 4.71 grams of the diimide solid from Example 10 was dissolved in 28.5 grams of PGMEA. Next, 68.5 grams of PGME was added. 0.14 grams of NF7177C, 0.14 grams of 3,3',5,5'-tetrakis(methoxymethyl)-[1,1'-biphenyl]-4,4'-diol ("TMOM-BP"), and 4.7 grams of 0.1% R30N surfactant were added. The solution was filtered through a 0.1 μm PTFE membrane filter.

[0111] [Example 23] SC1 resistance test The coating formulations from Examples 12, 20, 21, and 22 were spin-coated at 1,500 rpm for 60 seconds onto TiN-liner chips containing narrow trenches (50 nm lines, 50 nm spaces, and 200 nm deep trenches in each example). The chips were baked at 170°C for 1 minute on a hotplate and 4 minutes at 450°C in a furnace, after which they were plasma-etched to remove the coating in the open areas and partially remove the coating within the trenches. The chips were then immersed in SC1 etchant (ammonium hydroxide, hydrogen peroxide, and DI water in a 1:1:5 ratio) at 50°C for 100 seconds. After air drying, the chips were examined by SEM. The results (Figures 15-18) showed little undercut (i.e., less than 20 nm) on chips coated with the formulations from Examples 20, 21, and 22, making these formulations particularly well suited for use in processes incorporating SC1 etching.

[0112] [Example 24] Coating Compounds In this example, 4.71 grams of the diimide solid from Example 10 was dissolved in 90.25 grams of PGMEA and 4.75 grams of PGME. Next, 0.14 grams of NF7177C, 0.14 grams of phenyl phosphate, and 0.1 grams of R30N surfactant were added. The solution was mixed for 4 hours and then filtered through a 0.2 μm PTFE filter.

[0113] [Example 25] Coating Compounds In this example, 4.71 grams of the diimide solid from Example 10 was dissolved in 90.25 grams of PGMEA and 4.75 grams of PGME. Next, 0.14 grams of NF7177C, 0.14 grams of dimethylphenyl phosphate, and 0.1 grams of R30N surfactant were added. The solution was mixed for 4 hours and then filtered through a 0.2 μm PTFE filter.

[0114] [Example 26] Coating Compounds In this example, 4.71 grams of the diimide solid from Example 10 was dissolved in 90.25 grams of PGMEA and 4.75 grams of PGME. 0.14 grams of NF7177C, 0.14 grams of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and 0.1 grams of R30N surfactant were added. The solution was mixed for 4 hours and filtered through a 0.2 μm PTFE filter.

[0115] [Example 27] Coating Compounds In this example, 4.71 grams of the diimide solid from Example 10 was dissolved in 90.25 grams of PGMEA and 4.75 grams of PGME. Next, 0.14 grams of NF7177C, 0.14 grams of phenylphosphonic acid, and 0.1 grams of R30N surfactant were added. The solution was mixed for 4 hours and then filtered through a 0.2 μm PTFE filter.

[0116] [Example 28] SC1 resistance test The solutions from Examples 24-27 were spin-coated at 1,500 rpm for 60 seconds onto TiN-liner chips containing narrow trenches (50 nm lines, 50 nm spaces, and 200 nm deep trenches in each example). The chips were baked at 170 °C for 1 minute on a hotplate and 4 minutes at 450 °C in a furnace with N2 flow, followed by plasma etching to remove the coating in the open areas and partially remove the coating within the trenches. The chips were then immersed in SC1 etchant (ammonium hydroxide, hydrogen peroxide, and DI water, 1:1:5) at 60 °C for 100 seconds. After air drying, the chips were examined by SEM. The results showed that chips coated with the solutions from Examples 24-27 had significantly less undercutting than chips coated with the comparative solution without additives (i.e., the comparative solution contained 4.71 grams of the diimide solid from Example 10 dissolved in 90.25 grams of PGMEA and 4.75 grams of PGME). 19-23 show SEM cross sections of the coated substrates.

Claims

1. (i) a dianhydride and a crosslinkable monoamine, (ii) a crosslinkable monoanhydride and a diamine, or (iii) both (i) and (ii) a diimide formed from a diamic acid formed from Polyphenols containing at least four phenolic rings, polyhydroxy compounds, phosphorus compounds, and A combination of the above and a component selected from Solvent system and A composition comprising:

2. The composition of claim 1 , wherein the solvent system comprises propylene glycol monomethyl ether.

3. the dianhydride is selected from benzophenone-3,3',4,4'-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, and combinations thereof; the monoamine is selected from 2-vinylaniline, 4-vinylaniline, 2-allylaniline, 4-allylaniline, 3-ethynylaniline, 4-ethynylaniline, 2-ethynylaniline, and combinations thereof; the monoanhydride is selected from maleic anhydride, 4-cyclohexene-1,2-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, 4-ethynylphthalic anhydride, 4-methylethynylphthalic anhydride, 4-phenylethynylphthalic anhydride, and combinations thereof; 2. The composition of claim 1, wherein the diamine is selected from 4,4'-oxydianiline, bis(4-aminophenyl)sulfone, 9,9-bis(4-aminophenyl)fluorene, and combinations thereof.

4. The polyphenol 【Chemistry 1】 is selected from wherein n is 1 to 5, and the molecular chain may be attached to carbon α' instead of or in addition to carbon α; the polyhydroxy compound is selected from gallic acid, methyl gallate, 4-hydroxybenzoic acid, pyrogallol, 2,3,4,3',4',5'-hexahydroxybenzophenone, boronated polystyrene, 3,3',5,5'-tetrakis(methoxymethyl)-[1,1'-biphenyl]-4,4'-diol, and poly(4-vinylphenol), and combinations thereof; 4. The composition of claim 1, wherein the phosphate compound is selected from phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, and dimethylphenylphosphonate, phenylphosphate, phenylphosphonic acid, phytic acid, and combinations thereof.

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