Film-forming composition and silicon dioxide film and method for producing the same

Abstract

The present application belongs to the technical field of electronic device manufacturing, and provides a film forming composition, a silicon dioxide film and a preparation method thereof. The film forming composition comprises polysilazane, a phosphonamide compound and an organic solvent, wherein the phosphonamide compound has a structure shown in formula 1. The film forming composition of the present application can not only prepare a silicon dioxide film at a lower temperature, but also has lower residual stress, higher adhesion and excellent optical performance. Formula 1.

Description

Technical Field

[0001] This invention belongs to the field of electronic device manufacturing technology, specifically relating to a film forming composition and a silicon dioxide film and a method for preparing the same. Background Technology

[0002] Silica (SiO2) thin films, due to their excellent electrical insulation, high density, good light transmittance, and thermochemical stability, have been widely used in semiconductor packaging insulating layers, anti-reflective coatings for optical devices, and water-oxygen barrier layers for flexible electronic substrates. Currently, the main methods for preparing silica thin films include physical vapor deposition using silicon targets, chemical vapor deposition using silanes or tetraethyl orthosilicates as precursors, and sol-gel methods using alkoxysilanes such as tetraethyl orthosilicates as raw materials. However, these methods have limitations in terms of process complexity, film density, and adaptability to complex substrates.

[0003] Polysilazane (PSZ), as an inorganic polymer precursor, has a backbone composed of alternating silicon and nitrogen atoms (-Si-N-), and its molecular structure is rich in highly reactive Si-N bonds and active groups such as Si-H and NH. When PSZ is applied to a substrate, it undergoes a ceramic transformation through hydrolysis-condensation or oxidation reactions under high temperature, oxidizing atmosphere, or water vapor conditions. The Si-N bonds are gradually replaced by Si-O bonds, forming a silica network and ultimately obtaining a film. This film has a uniform structure and low impurity content, making PSZ a core precursor material for preparing high-performance silica films. Compared with traditional vapor deposition or sol-gel methods, the PSZ route offers significant advantages such as simple processing, dense film formation, good adaptability to complex substrates, and the ability to achieve liquid-phase coating.

[0004] However, the direct preparation of silica films using polysilazane still has significant drawbacks: its complete conversion to silica typically requires prolonged high-temperature heat treatment or treatment in a specific oxidation / hydrolysis atmosphere, which not only increases process energy consumption and equipment requirements but also hinders the application of heat-sensitive substrates. To reduce the conversion temperature and shorten the processing time, various catalysts have been introduced in related technologies, such as organotin and organotitanium compounds. While these can promote the breaking and oxidation of Si-N bonds to some extent, their catalytic efficiency remains limited. Other related technologies use organic amines (such as triethylamine and dimethylpyridine) or guanidine compounds as nucleophilic catalysts. These strongly basic substances can effectively attack silicon atoms, significantly reducing the ceramicization conversion temperature of polysilazane. However, while accelerating the reaction, amine or guanidine catalytic systems can easily lead to the formation of micropores or cracks within the film layer, reducing its density. In addition, rapid catalytic conversion often introduces large residual stress, causing film warping or decreased adhesion. The residual basic groups in some catalytic systems may also affect the refractive index of the film layer, thereby reducing its optical quality. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, the present invention aims to provide a film-forming composition, a silica film, and a method for preparing the same. The film-forming composition of the present invention not only enables the preparation of silica films at lower temperatures, but also produces silica films with low residual stress, high adhesion, and excellent optical properties.

[0006] In a first aspect, the present invention provides a film-forming composition comprising a polysilazane, a phosphonamide compound, and an organic solvent, wherein the phosphonamide compound has the structure shown in Formula 1: Formula 1, In Formula 1, L is an alkylene group having 1 to 10 carbon atoms; R1 and R2 may be the same or different, and each is independently hydrogen or an alkyl group having 1 to 6 carbon atoms; or, R1 and R2 may be connected together to form an alkylene group having 2 to 8 carbon atoms.

[0007] In some embodiments of the present invention, in Formula 1, L is an alkylene group having 2 to 6 carbon atoms; R1 and R2 are each independently an alkyl group having 1 to 4 carbon atoms, or R1 and R2 are connected together to form an alkylene group having 2 to 6 carbon atoms.

[0008] In some embodiments of the present invention, the phosphonamide compound is at least one of compound C1 and compound C2:

[0009] In some embodiments of the present invention, the polysilazane has the structural unit shown in Formula 2: Equation 2, Among them, R a R b and R c They may be the same or different, and each independently consists of hydrogen, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, wherein the substituent is an alkyl group having 1 to 4 carbon atoms.

[0010] Furthermore, the polysilazane is a perhydropolysilazane.

[0011] In some embodiments of the present invention, the polysilazane has a weight-average molecular weight of 500 to 8000.

[0012] In some embodiments of the present invention, the organic solvent is selected from at least one of alkylene glycol monoalkyl ether acetate, aliphatic ether, aliphatic ketone, carboxylic acid ester and aromatic hydrocarbon.

[0013] In some embodiments of the present invention, the polysilazane content is 20% to 40% based on the total mass of the film-forming composition; and the phosphonamide compound is 0.5 to 5 parts by mass relative to 100 parts by mass of the polysilazane.

[0014] Furthermore, the phosphonamide compound is 1 to 3 parts by mass relative to 100 parts by mass of the polysilazane.

[0015] In a second aspect, the present invention provides a method for preparing a silicon dioxide film, comprising: applying the film-forming composition described in the first aspect of the present invention onto a substrate and subjecting it to heat treatment to form a silicon dioxide film.

[0016] In some embodiments of the present invention, the heat treatment includes pre-baking and firing performed sequentially; wherein the pre-baking temperature T1 is 50~200℃ and the time is 20~600s; the firing temperature T2 is 100~700℃ and the time is 10~60min; and T1 < T2.

[0017] Furthermore, the firing is carried out in the presence of water vapor, and the firing temperature T2 is 120~220℃.

[0018] Thirdly, the present invention provides a silicon dioxide film prepared by the preparation method described in the second aspect of the present invention.

[0019] The film-forming composition provided by this invention is a film-forming liquid that uses polysilazane as a silica precursor and a phosphonamide compound with the structure shown in Formula 1 as a curing accelerator. This curing accelerator molecule contains four aziridinium groups. During calcination, these aziridinium groups act as strongly electrophilic active sites, cooperating with the Lewis base coordination of the phosphonyl groups to efficiently activate the Si-N bonds in the polysilazane molecule. This significantly reduces the activation energy for Si-N bond breaking and recombination, allowing the polysilazane to be converted into a dense silica film at a lower temperature. Furthermore, the flexible connecting arms, such as nitrogen-containing heterocyclic alkyl groups (e.g., piperazine rings) or alkylene groups, in the curing accelerator structure provide a molecular-level buffer space during the volume shrinkage process of the polysilazane-to-silica conversion, enabling molecular chain rearrangement and stress relaxation. This effectively suppresses residual tensile stress caused by volume shrinkage, preventing film cracking. The resulting silica film exhibits not only low residual stress but also excellent crack resistance. Furthermore, due to the extremely high reactivity of the aziridinyl group, it can chemically bond with the hydroxyl groups on the substrate surface, significantly enhancing the adhesion between the film and the substrate. Simultaneously, the formed silica has no residual carbon / nitrogen chromophores or pores, and its optical refractive index is low, approaching the optical properties of thermally grown silica.

[0020] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0021] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] The "scope" disclosed in this invention is defined in the form of a lower limit and / or an upper limit, whereby a given scope is defined by selecting a lower limit and / or an upper limit. This scope may or may not include endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form an undefined scope, and any lower limit can be combined with other lower limits to form an undefined scope, similarly, any upper limit can be combined with any other upper limit to form an undefined scope. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and can be combined with any other point or single value, or with other lower or upper limits, to form an undefined scope.

[0023] Unless otherwise specified, all embodiments and optional embodiments of the present invention may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present invention.

[0024] In this invention, alkyl groups can include straight-chain alkyl groups and branched-chain alkyl groups. Specific examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl (i.e., neopentyl), 1-methylbutyl, 2-methylbutyl, 3-methylbutyl (i.e., isopentyl), n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, n-heptyl, isoheptyl, n-octyl, isooctyl, n-nonyl, isononyl, etc. An alkylene group refers to a divalent group formed by the further loss of a hydrogen atom from an alkyl group.

[0025] In this invention, 3- to 10-membered cycloalkyl refers to monocyclic or polycyclic alkyl with 3 to 10 carbon atoms on the ring, and specific examples include, but are not limited to, cyclobutyl, cyclopentyl, cyclohexyl, and adamantyl.

[0026] In this invention, substituted or unsubstituted aryl refers to an aryl group having substituents or an unsubstituted aryl group. A "substituted" aryl group means that the hydrogen atoms on the aryl group can be replaced by one or more substituents. When the number of substituents is greater than one, the substituents can be the same or different. It should be understood that the number of carbon atoms in a substituted aryl group refers to the total number of carbon atoms in the aryl group and its substituents. For example, a substituted aryl group with 18 carbon atoms means that the total number of carbon atoms in the aryl group and its substituents is 18.

[0027] In this invention, specific examples of aryl groups include, but are not limited to, phenyl, naphthyl, biphenyl, and anthracene.

[0028] In this invention, " " indicates a connection key.

[0029] A first aspect of the present invention provides a membrane forming composition comprising a polysilazane, a phosphonamide compound, and an organic solvent.

[0030] In this invention, the phosphonamide compound has the structure shown in Formula 1: Formula 1, In Formula 1, L is an alkylene group having 1 to 10 carbon atoms; R1 and R2 may be the same or different, and each is independently hydrogen or an alkyl group having 1 to 6 carbon atoms; or, R1 and R2 may be connected together to form an alkylene group having 2 to 8 carbon atoms.

[0031] As an example, alkylenes having 1 to 10 carbon atoms can be selected from straight-chain alkylenes such as methylene, ethylene (-CH2CH2-), n-propylene (-CH2CH2CH2-), n-butylene, n-pentylene, n-hexylene, n-heptylene, n-octylene, n-nonylene, and n-decylene; as well as branched alkylenes such as isopropylene, sec-butylene, isobutylene, tert-butylene, and isopentylene.

[0032] In some embodiments, in Formula 1, L is an alkylene group having 2 to 6 carbon atoms, such as ethylene, n-propylene, n-butylene, or n-pentylene.

[0033] In some embodiments, R1 and R2 are each independently an alkyl group having 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, or tert-butyl.

[0034] In some embodiments, R1 and R2 are linked together to form an alkylene group having 2 to 6 carbon atoms, such as ethylene, n-propylene, n-butylene, or n-pentylene. Further, the alkylene group formed by linking R1 and R2 together is of the same type as the alkylene group of L.

[0035] In this invention, when R1 and R2 are linked together to form an alkylene group, the... It has a cyclic structure. For example, when R1 and R2 are linked together to form an alkylene group, such as n-propylene or n-butylene, They are respectively , .

[0036] Preferably, the phosphonamide compound is at least one of compound C1 (CAS: 738-99-8) and compound C2 (CAS: 3773-02-2).

[0037]

[0038] In this invention, the content of the phosphonamide compound can be selected according to the mass of the polysilazane. According to some embodiments, relative to 100 parts by mass of the polysilazane, the phosphonamide compound can be 0.5 to 5 parts by mass, for example, 0.5 parts by mass, 0.8 parts by mass, 1.0 parts by mass, 1.5 parts by mass, 2.0 parts by mass, 2.5 parts by mass, 3.2 parts by mass, 3.4 parts by mass, or 4 parts by mass. When the amount of the phosphonamide compound is too low, the Si-N bonds in the polysilazane may not be sufficiently activated, easily leading to a low firing conversion rate, an undense film layer, and affecting film quality; when the amount is too high, excessive P atoms may remain in the film, increasing the refractive index and stress. Preferably, relative to 100 parts by mass of the polysilazane, the phosphonamide compound is 1 to 3 parts by mass.

[0039] This invention does not impose any particular limitation on the polysilazane, as long as it can be used as a polymer precursor for preparing silica films. As some embodiments, the polysilazane has the structural unit shown in Formula 2: Equation 2, Among them, R a R b and R c They may be the same or different, and each independently consists of hydrogen, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, wherein the substituent is an alkyl group having 1 to 4 carbon atoms.

[0040] In this invention, the degree of polymerization of the polysilazane (i.e., the number of structural units shown in Formula 2) can be an integer from 2 to 1000, preferably an integer from 10 to 300.

[0041] In Formula 2, specific examples of alkyl groups having 1 to 8 carbon atoms include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 1-ethylbutyl, n-heptyl, n-octyl, etc. Specific examples of cycloalkyl groups having 3 to 10 carbon atoms include, but are not limited to, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, etc. Specific examples of substituted or unsubstituted aryl groups having 6 to 18 carbon atoms include, but are not limited to, phenyl, tolyl, dimethylphenyl, naphthyl, biphenyl, etc. Preferably, R a R b and R c All of them are hydrogen, that is, the polysilazane is a perhydropolysilazane (PHPS).

[0042] In this invention, the weight-average molecular weight (Mw) of the polysilazane is typically 400-13000, for example, 450, 500, 800, 1000, 1400, 1500, 2000, 2300, 3000, 3800, 5000, 8000, or 9000. To further improve film density and reduce internal stress, the weight-average molecular weight of the polysilazane is preferably 500-8000, more preferably 800-3000. The molecular weight of the polysilazane can be obtained by gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the mobile phase and polystyrene as the standard.

[0043] In this invention, the polysilazane can be commercially available or prepared using methods known in the art. As some examples, taking perhydropolysilazane as an example, its preparation method may include: mixing pyridine and dichlorosilane at a molar ratio of (10~20):1 under an inert gas (such as nitrogen, argon, or helium), stirring the mixture at -15°C to -10°C for 0.5~2 h to form a white solid complex (i.e., H2SiCl2·2Py); then heating to -5°C to 5°C, introducing ammonia gas, controlling the molar amount of ammonia to be 2~10 times that of dichlorosilane (preferably an ammonia-silane molar ratio > 2.8, where the ammonia-silane molar ratio refers to the molar ratio of ammonia to dichlorosilane), and then heating to reflux and stirring the mixture for 1~3 h. After the reaction is complete, the reaction mixture is washed with an anhydrous solvent (e.g., diethyl ether, pentane, or n-hexane) under an inert atmosphere, filtered, to obtain a pyridine solution of perhydropolysilazane. Finally, pyridine was removed by vacuum distillation at 30–60 °C to obtain perhydropolysilazane. The reaction equation is shown below: H2SiCl2+ 2 Py → H2SiCl2·2Py n H2SiCl2·2Py + 3n NH3→ [SiH2NH]n+ 2n NH4Cl + 2n Py, where n represents the degree of polymerization.

[0044] In some embodiments, the mass content of the polysilazane can be 20% to 40% based on the total weight of the film-forming composition, for example 20%, 23%, 24.5%, 25%, 28%, 30%, 35%, 38% or 40%.

[0045] The present invention does not particularly limit the organic solvent, as long as it can dissolve the other components in the composition. As some embodiments, the organic solvent may be selected from at least one of alkylene glycol monoalkyl ether acetates, aliphatic ethers, aliphatic ketones, carboxylic acid esters, and aromatic hydrocarbons. Further, specific examples of the alkylene glycol monoalkyl ether acetates include, but are not limited to, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), and propylene glycol monoethyl ether acetate. Specific examples of the aliphatic ethers include, but are not limited to, diethyl ether, dipropyl ether, di-n-butyl ether, di-tert-butyl ether, cyclopentylmethyl ether, and tetrahydrofuran. Specific examples of the aliphatic ketones include, but are not limited to, methyl ethyl ketone, cyclohexanone, 2-heptanone, and 3-heptanone. Specific examples of the carboxylic acid esters include, but are not limited to, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutyl propionate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, n-pentyl formate, isopentyl acetate, benzyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, methyl acetoacetate, ethyl acetoacetate, and ethyl 2-oxobutyrate. Specific examples of the aromatic hydrocarbons include, but are not limited to, toluene and xylene.

[0046] In some embodiments, the mass content of the organic solvent may be 58% to 78%, for example 60%, 62%, 65%, 70%, 74%, 75%, or 78%, based on the total weight of the film-forming composition.

[0047] In some embodiments, the mass content of the phosphonamide compound can be 0.2% to 2% based on the total weight of the film-forming composition, for example, 0.25%, 0.50%, 0.62%, 0.70%, 0.75%, 1.20%, 1.25%, 1.50%, 1.76%, or 1.90%.

[0048] The present invention does not particularly limit the preparation method of the membrane forming composition. Exemplarily, the polysilazane and phosphonamide compound can be added to the organic solvent and thoroughly mixed by mechanical stirring or ultrasonic treatment to form a homogeneous and stable solution. Then, the solution is filtered using a microporous filter with a pore size of 0.1~0.2μm, and the resulting filtrate is the membrane forming composition.

[0049] A second aspect of the present invention provides a method for preparing a silicon dioxide film, the method comprising: applying the film-forming composition described in the first aspect of the present invention onto a substrate and subjecting it to heat treatment to form a silicon dioxide film.

[0050] In this invention, the substrate material can be selected from silicon wafers, glass, stainless steel, or polyimide, and can be used in semiconductor or liquid crystal devices. The application method can be, for example, spin coating, slot coating, screen printing, inkjet printing, dip coating, or roll coating. Spin coating is preferred to ensure film thickness stability and improve process efficiency.

[0051] In some embodiments, the heat treatment includes a pre-baking and firing process performed sequentially.

[0052] Pre-baking effectively removes organic solvents from the wet film, improving process efficiency. The pre-baking temperature T1 can be 50~200℃, for example 50℃, 70℃, 80℃, 95℃, 100℃, 120℃, 150℃ or 180℃, preferably 80~150℃; the pre-baking time can be 20~600s, for example 30s, 40s, 60s, 90s, 120s, 180s, 300s, 420s or 500s, preferably 30~300s. The pre-baking can be carried out on a hot plate or in an oven.

[0053] The firing process aims to cause the polysilazane to undergo hydrolysis, condensation, and oxidation reactions, transforming it into a dense silica film. The firing temperature T2 is 100~700℃, for example, 120℃, 150℃, 180℃, 200℃, 220℃, 300℃, 350℃, 400℃, 450℃, 500℃, 600℃, or 700℃, and T2 > T1. Furthermore, the firing time can be 10~60 min, for example, 10 min, 15 min, 20 min, 30 min, 50 min, or 60 min, preferably 15~40 min.

[0054] As a preferred example, the calcination is carried out in the presence of water vapor. Under the influence of water vapor, water molecules can effectively attack the Si-N bonds, promoting the formation and condensation of silanol groups into a Si-O-Si network, thereby obtaining a highly dense, low-defect silicon dioxide film at a lower temperature. In contrast, calcination in a water-vapor-free atmosphere (such as air or nitrogen) requires a relatively high temperature to achieve the conversion and is prone to causing film cracking. To balance film quality and low-temperature processing, the calcination temperature in a water vapor atmosphere is 120–220°C.

[0055] A third aspect of the present invention provides a silicon dioxide film prepared by the preparation method described in the second aspect of the present invention. The silicon dioxide film has low internal stress, is crack-free, has high adhesion, and a low refractive index, making it particularly suitable for substrates that are not resistant to high temperatures (such as flexible polymer substrates). It can be used as a highly reliable optical antireflective film, protective film, or insulating dielectric layer.

[0056] In some embodiments, the thickness of the silicon dioxide film can be 0.05~2.0μm, for example 0.1μm, 0.2μm, 0.5μm, 1.0μm or 1.5μm.

[0057] The following describes embodiments of the present invention. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0058] Synthesis example 1 This synthesis example illustrates the method for synthesizing all-hydrogen polynitrosilanes used in the following embodiments and comparative examples.

[0059] In a four-necked flask equipped with a gas delivery tube, mechanical stirrer, and cold trap, 1.25 L of pyridine (Py, 15.53 mol) and 126.25 g of dichlorosilane (H₂SiCl₂, 1.25 mol) were added under nitrogen protection. The mixture was stirred at -10 °C for 1 h to form a white solid complex (H₂SiCl₂·2Py). Subsequently, dry ammonia gas (NH₃) was continuously introduced at 0 °C until the molar ratio of the total amount of ammonia introduced to dichlorosilane was greater than 2.8. The mixture was then heated to reflux and reacted for 2 h. After the reaction was completed, the reaction mixture was filtered under nitrogen protection. The filter cake was washed with anhydrous n-hexane and filtered to obtain 2.25 L of a pyridine solution of perhydropolysilazane. The solution was distilled under reduced pressure (50 °C, 100 Pa) to remove the solvent, yielding a colorless and transparent perhydropolysilazane (42.3 g, yield 75.2%). According to GPC testing (using THF as the mobile phase and polystyrene as the standard), the Mw of the perhydropolysilazane is 1500.

[0060] The following examples illustrate the film-forming composition and its preparation method of the present invention.

[0061] Example 1 Under nitrogen protection, 10g of perhydropolysilazane (PHPS), 0.2g of curing accelerator (compound C1) and 30g of xylene were mixed and stirred at room temperature for 12h. The mixture was then filtered through a 0.2μm PTFE filter to obtain a film-forming composition (i.e., film-forming solution), denoted as F1.

[0062]

[0063] Example 2 Under nitrogen protection, 10g of perhydropolysilazane, 0.1g of compound C1 and 30g of xylene were mixed and stirred at room temperature for 12h. The mixture was then filtered through a 0.2μm PTFE filter to obtain the film-forming solution, denoted as F2.

[0064] Example 3 Under nitrogen protection, 10g of perhydropolysilazane, 0.3g of compound C1 and 30g of xylene were mixed and stirred at room temperature for 12h. The mixture was then filtered through a 0.2μm PTFE filter to obtain the film-forming solution, denoted as F3.

[0065] Example 4 Under nitrogen protection, 10g of perhydropolysilazane, 0.5g of compound C1 and 30g of xylene were mixed and stirred at room temperature for 12h. The mixture was then filtered through a 0.2μm PTFE filter to obtain the film-forming solution, denoted as F4.

[0066] Example 5 Under nitrogen protection, 10g of perhydropolysilazane, 0.2g of compound C2 and 22g of xylene were mixed and stirred at room temperature for 15h. The mixture was then filtered through a 0.2μm PTFE filter to obtain the film-forming solution, denoted as F5.

[0067]

[0068] Comparative Example 1 Under nitrogen protection, 10g of perhydropolysilazane, 0.2g of 1,1,2,3,3-pentamethylguanidine and 30g of xylene were mixed and stirred at room temperature for 12h. The mixture was then filtered through a 0.2μm PTFE filter to obtain the film-forming solution, denoted as F-D1.

[0069] The contents of each component in the film-forming solution in the above examples and comparative examples are shown in Table 1.

[0070] Table 1

[0071] The following application examples illustrate the silica film and its preparation method of the present invention.

[0072] Application Example 1 In a nitrogen atmosphere, film-forming solution F1 was spin-coated onto a silicon substrate (50 mm in diameter) to form a wet film. The wet film was then placed on a hot plate and pre-baked at 100°C for 60 seconds. The pre-baked film was then transferred to a tube furnace equipped with a steam generator and heated at 180°C for 20 minutes in a nitrogen atmosphere containing water vapor (3.0 vol%) to obtain a silicon dioxide film with a thickness of approximately 200 nm.

[0073] Application Examples 2-4 A silica film was prepared by referring to the method of Application Example 1, except that the film-forming solution F1 was replaced with film-forming solutions F2 to F4 respectively.

[0074] Application Example 5 In a nitrogen atmosphere, film-forming solution F5 was spin-coated onto a silicon substrate (50 mm in diameter) to form a wet film. The wet film was then placed on a hot plate and pre-baked at 100°C for 60 seconds. The pre-baked film was transferred to a tube furnace equipped with a steam generator and heated at 165°C for 25 minutes in a nitrogen atmosphere containing water vapor (3.0 vol%) to obtain a silicon dioxide film with a thickness of approximately 200 nm.

[0075] Application Comparative Example 1 A silica film was prepared by referring to the method in Application Example 1, except that the film-forming solution F1 was replaced with film-forming solution F-D1.

[0076] Test case This test case is used to illustrate the performance of the silica film in the above application examples and comparative examples.

[0077] 1) Residual stress test Residual stress was measured using a thin film stress measuring device FLX-3300-T (Dongpeng Technology), with a test temperature of 25±2℃ and a scanning length of 40mm. Each sample was measured 3 times and the average value was taken.

[0078] 2) Crack resistance test The entire sample surface was observed using a 100x optical microscope and rated according to the following criteria.

[0079] A: No cracks were observed; B: Slight cracks were observed, specifically: 1 to 5 microcracks with a length of less than 30 μm at the edge or in a local area; C: Cracks were observed in some areas, specifically: there were more than 6 cracks in multiple locations or cracks with a length greater than 30μm. D: Cracks are present throughout the entire sample.

[0080] 3) Adhesion test Referring to the testing standard GB / T 9286-2021, a 1mm × 1mm grid pattern is drawn on the surface of the silicon film using a knife. Adhesive tape is tightly adhered to the grid area, pressed and held for 1 minute, then quickly peeled off. The peeling rate is rated based on the percentage of film area detached within the grid area. Specifically: 5B: 0% peeling rate; 4B: 0% < peeling rate < 5%; 3B: 5% ≤ peeling rate < 15%; 2B: 15% ≤ peeling rate < 35%; 1B: 35% ≤ peeling rate < 65%; 0B: peeling rate ≥ 65%.

[0081] 4) Refractive index The measurements were taken at a wavelength of 633 nm using a spectrophotometer M-2000V (JA Woolam), and the average value of three different positions was taken for each sample.

[0082] The test results are shown in Table 2.

[0083] Table 2

[0084] As shown in Table 2, compared with the silica film prepared by the film-forming solution (F-D1) of Comparative Example 1, the silica films prepared by the film-forming solutions (F1-F5) of Examples 1-5 have lower residual stress, better crack resistance, and higher adhesion. Regarding refractive index, the films prepared by Examples 1-5 have a refractive index of 1.46-1.52 at a wavelength of 633 nm, similar to the refractive index of conventional silicon films (approximately 1.46); while the refractive index of Comparative Example 1 is as high as 2.32, significantly deviating from the normal value. An excessively high refractive index often indicates abnormal film composition or inappropriate density, which can easily lead to leakage. Therefore, the silica film of this invention is more suitable as an insulating film.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A composition for film formation, characterized in that, It comprises polysilazane, phosphonamide compounds, and an organic solvent, wherein the phosphonamide compounds have the structure shown in Formula 1: Formula 1, In Formula 1, L is an alkylene group having 1 to 10 carbon atoms; R1 and R2 may be the same or different, and each is independently hydrogen or an alkyl group having 1 to 6 carbon atoms; Alternatively, R1 and R2 can be linked together to form an alkylene group with 2 to 8 carbon atoms.

2. The film-forming composition according to claim 1, characterized in that, In Formula 1, L is an alkylene group having 2 to 6 carbon atoms; R1 and R2 are each independently an alkyl group having 1 to 4 carbon atoms; Alternatively, R1 and R2 can be linked together to form an alkylene group with 2 to 6 carbon atoms.

3. The film-forming composition according to claim 1 or 2, characterized in that, The phosphonamide compound is at least one of compound C1 and compound C2: 。 4. The film-forming composition according to any one of claims 1-3, characterized in that, The polysilazane has the structural unit shown in Formula 2: Equation 2, Among them, R a R b and R c They may be the same or different, and each independently consists of hydrogen, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 18 carbon atoms, wherein the substituent is an alkyl group having 1 to 4 carbon atoms.

5. The film-forming composition according to any one of claims 1-4, characterized in that, The polysilazane is a perhydropolysilazane; Preferably, the polysilazane has a weight-average molecular weight of 500 to 8000.

6. The film-forming composition according to any one of claims 1-5, characterized in that, The organic solvent is selected from at least one of alkylene glycol monoalkyl ether acetate, aliphatic ether, aliphatic ketone, carboxylic acid ester and aromatic hydrocarbon.

7. The film-forming composition according to any one of claims 1-6, characterized in that, Based on the total mass of the film-forming composition, the mass content of the polysilazane is 20% to 40%; The phosphonamide compound is 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, relative to 100 parts by weight of the polysilazane.

8. A method for preparing a silicon dioxide film, characterized in that, include: The film-forming composition according to any one of claims 1-7 is applied to a substrate and subjected to heat treatment to form a silicon dioxide film.

9. The preparation method according to claim 8, characterized in that, The heat treatment includes a pre-baking and firing process performed sequentially; wherein... The pre-baking temperature T1 is 50~200℃, and the time is 20~600s; The firing temperature T2 is 100~700℃, and the firing time is 10~60min; and T1 < T2; Preferably, the firing is carried out in the presence of water vapor, and the firing temperature T2 is 120~220℃.

10. A silica film prepared by the preparation method according to claim 8 or 9.

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